G2Cdb::Gene report

Gene id
G00001473
Gene symbol
GNAS (HGNC)
Species
Homo sapiens
Description
GNAS complex locus
Orthologue
G00000224 (Mus musculus)

Databases (8)

Curated Gene
OTTHUMG00000033069 (Vega human gene)
Gene
ENSG00000087460 (Ensembl human gene)
2778 (Entrez Gene)
24 (G2Cdb plasticity & disease)
GNAS (GeneCards)
Literature
139320 (OMIM)
Marker Symbol
HGNC:4392 (HGNC)
Protein Sequence
Q5JWF2 (UniProt)

Synonyms (5)

  • GNASXL
  • GPSA
  • NESP
  • NESP55
  • SCG6

Diseases (31)

Disease Nervous effect Mutations Found Literature Mutations Type Genetic association?
D00000293: Albright hereditary osteodystrophy Y Y (1505964) Deletion (D) Y
D00000144: Pseudohypoparathyroidism type 1a N Y (8557265) Deletion (D) Y
D00000144: Pseudohypoparathyroidism type 1a N Y (8809352) Single nucleotide polymorphism (SNP) Y
D00000152: Testotoxicosis N Y (8809352) Single nucleotide polymorphism (SNP) Y
D00000143: Pseudohypoparathyroidism N Y (9876352) Deletion (D) Y
D00000143: Pseudohypoparathyroidism N Y (9876352) Microinsertion (MI) Y
D00000143: Pseudohypoparathyroidism N Y (9876352) Microinsertion (MI) Y
D00000144: Pseudohypoparathyroidism type 1a N Y (10094437) Deletion (D) Y
D00000231: Essential hypertension N Y (10406816) Single nucleotide polymorphism (SNP) Y
D00000293: Albright hereditary osteodystrophy Y Y (10487696) Deletion (D) Y
D00000260: Fibrous dysplasia N Y (10646121) Unknown (?) Y
D00000145: Pseudohypoparathyroidism type 1b N Y (11029463) Deletion (D) Y
D00000112: Platelike osteoma cutis N Y (11092389) Deletion (D) Y
D00000264: Progressive osseous heteroplasia N Y (11092390) Nonsense (No) Y
D00000144: Pseudohypoparathyroidism type 1a N Y (11095461) Deletion (D) Y
D00000147: Acromegaly N Y (11158006) No mutation found (N) N
D00000261: Mazabraud syndrome N Y (11241472) No mutation found (N) N
D00000293: Albright hereditary osteodystrophy Y Y (11412411) Single nucleotide polymorphism (SNP) Y
D00000131: Enhanced trauma-related bleeding tendency N Y (11583302) Insertion (I) Y
D00000131: Enhanced trauma-related bleeding tendency N Y (11583302) Single nucleotide polymorphism (SNP) Y
D00000293: Albright hereditary osteodystrophy Y Y (11600516) Microinsertion (MI) Y
D00000293: Albright hereditary osteodystrophy Y Y (11600516) Insertion (I) Y
D00000293: Albright hereditary osteodystrophy Y Y (11600516) Deletion (D) Y
D00000293: Albright hereditary osteodystrophy Y Y (11600516) Splice site mutation (SpS) Y
D00000264: Progressive osseous heteroplasia N Y (11784876) Unknown (?) Y
D00000144: Pseudohypoparathyroidism type 1a N Y (11788646) Microinsertion (MI) Y
D00000144: Pseudohypoparathyroidism type 1a N Y (11788646) Unknown (?) Y
D00000146: Pseudohypoparathyroidism type 1c N Y (11788646) Microinsertion (MI) Y
D00000146: Pseudohypoparathyroidism type 1c N Y (11788646) Unknown (?) Y
D00000144: Pseudohypoparathyroidism type 1a N Y (11926205) Microinsertion (MI) Y
D00000144: Pseudohypoparathyroidism type 1a N Y (11926205) Deletion (D) Y
D00000144: Pseudohypoparathyroidism type 1a N Y (11926205) Insertion (I) Y
D00000294: McCune-Albright syndrome N Y (12199346) Microinsertion (MI) Y
D00000149: Cushing's syndrome (ACTH-independent) N Y (12373631) No mutation found (N) N
D00000293: Albright hereditary osteodystrophy Y Y (12407707) Deletion (D) Y
D00000293: Albright hereditary osteodystrophy Y Y (12621129) Single nucleotide insertion (SNI) Y
D00000293: Albright hereditary osteodystrophy Y Y (12621129) Deletion (D) Y
D00000293: Albright hereditary osteodystrophy Y Y (12621129) Single nucleotide polymorphism (SNP) Y
D00000293: Albright hereditary osteodystrophy Y Y (12621129) Single nucleotide deletion (SND) Y
D00000293: Albright hereditary osteodystrophy Y Y (12621129) Microinsertion (MI) Y
D00000293: Albright hereditary osteodystrophy Y Y (12621129) Nonsense (No) Y
D00000293: Albright hereditary osteodystrophy Y Y (12656668) Single nucleotide polymorphism (SNP) Y
D00000148: Cushing's syndrome N Y (12727968) Microinsertion (MI) Y
D00000295: McCune-Albright syndrome with precocious puberty N Y (12729407) Microinsertion (MI) Y
D00000083: Thyroid carcinoma in McCune-Albright syndrome N Y (12970318) Unknown (?) Y
D00000264: Progressive osseous heteroplasia N Y (14723729) Microinsertion (MI) Y
D00000294: McCune-Albright syndrome N Y (15126527) Microinsertion (MI) Y
D00000151: Premature thelarche N Y (15289771) Microinsertion (MI) Y
D00000214: Autonomic nervous system activity Y Y (15479166) Single nucleotide polymorphism (SNP) Y
D00000153: Obesity N Y (15531240) Single nucleotide polymorphism (SNP) N
D00000062: Transitional cell carcinoma of the bladder N Y (15824158) Single nucleotide polymorphism (SNP) Y
D00000232: Hypertension N Y (15894831) Single nucleotide polymorphism (SNP) Y
D00000139: Diabetes mellitus N Y (15894831) Single nucleotide polymorphism (SNP) N
D00000153: Obesity N Y (15917856) Polymorphism (P) Y
D00000022: Colorectal cancer N Y (16033819) Single nucleotide polymorphism (SNP) Y
D00000293: Albright hereditary osteodystrophy Y Y (16116826) Nonsense (No) Y
D00000143: Pseudohypoparathyroidism N Y (16116826) Nonsense (No) Y
D00000320: Athletic performance N Y (16210433) Single nucleotide polymorphism (SNP) Y
D00000167: Schizophrenia (deficit) Y Y (16406317) Single nucleotide polymorphism (SNP) Y
D00000058: Clear renal cell carcinoma N Y (16467086) Single nucleotide polymorphism (SNP) Y
D00000088: B-cell chronic lymphocytic leukaemia N Y (17020971) Single nucleotide polymorphism (SNP) Y
D00000150: Polycystic ovary syndrome N Y (17062894) Single nucleotide polymorphism (SNP) N
D00000107: Invasive breast carcinoma N Y (17186357) Single nucleotide polymorphism (SNP) Y

References

  • The T393C polymorphism in the gene GNAS1 of G protein is associated with survival of patients with invasive breast carcinoma.

    Otterbach F, Callies R, Frey UH, Schmitz KJ, Wreczycki C, Kimmig R, Siffert W and Schmid KW

    Institute of Pathology and Neuropathology, University Hospital of Essen, University of Duisburg-Essen, Hufelandstrasse 55, D-45122, Essen, Germany.

    The GNAS1 locus encodes the G(alpha)s protein which stimulates the formation of cyclic AMP (cAMP). Subsequently the cAMP pathway mediates various pleiotropic effects including regulation of apoptosis and proliferation. We have recently shown that genotypes of the single nucleotide polymorphism (SNP) T393C in the gene GNAS1 are associated with survival of patients suffering from bladder, renal cell and colorectal carcinoma. In the present study, the genotypes of the T393C SNP were determined in 279 patients with invasive breast carcinoma. Comparing the genotypes with the overall survival as well as important clinico-pathological parameters showed that carriers of the T allele had a significantly less favourable course of the disease when compared to carriers of the homozygous CC genotype. In multivariate analysis the homozygous TT genotype was independently associated with a decreased overall survival. Our results suggest that the GNAS1 T393C SNP is a novel genetic host factor for disease progression in patients with invasive breast carcinoma.

    Breast cancer research and treatment 2007;105;3;311-7

  • The CC genotype of the GNAS T393C polymorphism is associated with obesity and insulin resistance in women with polycystic ovary syndrome.

    Hahn S, Frey UH, Siffert W, Tan S, Mann K and Janssen OE

    Endokrinologikum Ruhr, Center for endocrine and metabolic diseases, Alter Markt 4, 44866 Bochum, Germany. susanne.hahn@endokrinologikum.com

    Objective: Variants in the Gs protein alpha subunit gene (GNAS1) are known to be involved in the pathogenesis of several endocrine and metabolic disorders. To understand genetic determinants of androgen excess, insulin resistance, and obesity in polycystic ovary syndrome (PCOS), we investigated the effect of the common GNAS1 T393C polymorphism on the phenotype of German PCOS women.

    Design: Two hundred and seventy-eight PCOS women and 820 Caucasian controls were genotyped for the common T393C polymorphism in GNAS1. To this end, genomic DNA was amplified by PCR with specific oligonucleotides and genotypes were determined using the restriction enzyme FokI. In addition, we evaluated whether the T393C polymorphism had an influence on the response to 6 months metformin treatment in a subgroup of 105 PCOS women.

    Methods: Anthropometric variables, metabolic parameters including indices of insulin resistance measured by oral glucose tolerance testing, and endocrine biochemical as well as clinical parameters were measured in all PCOS subjects.

    Results: GNAS1 genotype distributions were not significantly different between PCOS women and controls. In PCOS women, no significant differences in endocrine clinical and biochemical variables were found between the genotypes. However, the C-allele carrier group had significantly higher mean body weight, body mass index, leptin levels, and higher indices of insulin resistance compared with women with GNAS1 TT-genotype. Metformin treatment significantly improved hyperandrogenism, menstrual cyclicity, body weight, and insulin resistance independent of GNAS1 genotype. The major determinant of weight loss was body weight before treatment.

    Conclusion: The T393C polymorphism is not associated with PCOS in Caucasian women, but may represent a genetic marker for increased susceptibility for obesity in this cohort.

    European journal of endocrinology 2006;155;5;763-70

  • The GNAS1 T393C polymorphism is associated with disease progression and survival in chronic lymphocytic leukemia.

    Frey UH, Nückel H, Sellmann L, Siemer D, Küppers R, Dürig J, Dührsen U and Siffert W

    Institut für Pharmakogenetik, Universitätsklinikum Essen, Hufelandstrasse 55, D-45122 Essen, Germany. Ulrich.Frey@uni-essen.de

    Purpose: B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of monoclonal mature B cells. The G protein Galphas subunit has been linked to proapoptotic processes in cancer cell lines. The TT genotype of the GNAS1 T393C polymorphism is associated with increased Galphas transcript levels and a more favorable clinical course in different solid cancers.

    We retrospectively genotyped 144 patients with B-CLL to examine a potential association between T393C genotypes with progression-free survival (time from diagnosis to initiation of chemotherapy) and overall survival.

    Results: The C-allele frequency in the patient group was 0.57 and not significantly different from that of healthy blood donors. Median progression-free survival was significantly different between genotypes (TT 130 months; TC 100 months; CC 31 months; P = 0.0066). Multivariable analysis showed that besides of ZAP-70 (P = 0.005) and Binet stage (P < 0.001), the T393C polymorphism was an independent prognostic factor for progression-free survival [hazard ratio (HR) CC versus TT 2.7; P = 0.010]. In Binet A stages, ZAP-70-positive patients with CC genotypes had a HR of 4.4 to receive first therapy compared with ZAP-70-negative patients with T-alleles (P = 0.0001). Regarding overall survival, CC genotypes (median overall survival, 197 months) were at highest risk for death compared with T-alleles (median overall survival, 310 months) in both univariate (HR, 4.8; P < 0.0001) and multivariable analysis (HR, 5.6; P = 0.002).

    Conclusions: Here, we show that the GNAS1 T393C status is a novel independent prognostic marker in patients with B-CLL. These results could help to define patients who could benefit from an early individualized therapy.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2006;12;19;5686-92

  • The T393C polymorphism of the GNAS1 gene is associated with deficit schizophrenia in an Italian population sample.

    Minoretti P, Politi P, Coen E, Di Vito C, Bertona M, Bianchi M and Emanuele E

    Interdepartmental Center for Research in Molecular Medicine (CIRMC), University of Pavia, Viale Taramelli 24, I-27100 Pavia, Italy.

    Programmed cell death and alterations in intracellular G-protein signaling may be involved in the pathophysiology of schizophrenia. The Galphas subunit of heterotrimeric G-proteins, encoded by the gene GNAS1, may play a role in both of these processes. Additionally, transgenic mice expressing a constitutively active form of Galphas provide a reliable model of certain endophenotypes of schizophrenia. To investigate whether the functional single nucleotide polymorphism T393C in GNAS1 gene could affect risk of schizophrenia, we examined its distribution in Italian subjects with (n=383) and without (n=400) schizophrenia. We also evaluated whether a specific association could exist between the deficit (n=108) and nondeficit (n=275) forms of the disorder. The alleles and genotypes frequency in the entire cohort of schizophrenic patients did not differ from that of controls. However, the frequency of the homozygous 393TT genotype was significantly higher in deficit schizophrenic patients (37.1%) compared to both nondeficit schizophrenic (22.5%, p=0.011) and controls (22.8%, p=0.015). This association with deficit schizophrenia persisted even after allowance for potential confounders [adjusted odds ratio (OR) for deficit schizophrenia: 2.06 (95% confidence interval (CI): 1.21-3.47), p=0.007]. Altogether, our data suggest that the GNAS1 T393C status could influence susceptibility for deficit schizophrenia in Italian subjects.

    Neuroscience letters 2006;397;1-2;159-63

  • The GNAS1 T393C polymorphism predicts survival in patients with clear cell renal cell carcinoma.

    Frey UH, Lümmen G, Jäger T, Jöckel KH, Schmid KW, Rübben H, Müller N, Siffert W and Eisenhardt A

    Institut für Pharmakogenetik, Universitätsklinikum Essen, Germany. Ulrich.Frey@uni-essen.de

    Purpose: G proteins mediate signaling from cell surface receptors to specific intracellular proteins. In vitro cancer cell line studies revealed a link between the Galphas protein and proapoptotic processes. We have recently shown that TT genotypes of the GNAS1 T393C polymorphism display increased transcription of Galphas and a more favorable clinical course in bladder and colorectal cancer patients compared both with TC or CC genotypes.

    In the present study, 150 patients with clear cell renal cell carcinoma surgically treated by nephrectomy with curative intent were retrospectively genotyped to elucidate a potential association between T393C genotypes and clinical outcome.

    Results: The C-allele frequency in the renal cell carcinoma patient group was 0.51, which is not significantly different from that of a healthy blood donor group. Kaplan-Meier curves for tumor progression, development of metastasis, and tumor-related death showed a significant association of the T393C polymorphism with outcome (5-year cancer-specific survival rates: TT, 91%; TC, 81%; CC, 69%; P = 0.015). Multivariate Cox proportional analysis of a 10-year follow-up confirmed the T393C polymorphism as an independent prognostic factor in clear cell renal cell carcinoma. Homozygous CC patients were at highest risk for progression (hazard ratio, 2.48; P = 0.009) or tumor-related death (hazard ratio, 3.15; P = 0.018) compared with T-allele carriers.

    Conclusion: Our results show that besides tumor stage, lymph node status, and tumor grade, the GNAS1 T393C status is a novel independent host factor for disease progression in patients with clear cell renal cell carcinoma and provides further evidence for the T393C polymorphism as a general prognostic tumor marker.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2006;12;3 Pt 1;759-63

  • Effects of polymorphisms in beta1-adrenoceptor and alpha-subunit of G protein on heart rate and blood pressure during exercise test. The Finnish Cardiovascular Study.

    Nieminen T, Lehtimäki T, Laiho J, Rontu R, Niemelä K, Kööbi T, Lehtinen R, Viik J, Turjanmaa V and Kähönen M

    Dept. of Pharmacological Sciences, Medical School, Univ. of Tampere, Tampere FI-33014, Finland. tuomo.nieminen@iki.fi

    We tested whether the Arg389Gly and Ser49Gly polymorphisms of the beta1-adrenergic receptor gene ADRB1 and the T393C polymorphism of the G protein alpha-subunit gene GNAS1 modulate heart rate (HR) and blood pressure responses during an exercise stress test. The study population comprised 890 participants (563 men and 327 women, mean age 58.1 +/- 12.6 yr) of the Finnish Cardiovascular Study. Their HR, systolic (SAP), and diastolic arterial pressures (DAP) at rest, during exercise, and 4 min after the test were measured and analyzed by repeated-measurement ANOVA (RANOVA). Genotypes were detected by TaqMan 5' nuclease assay. In all subjects, and in men and women separately, the T393C of GNAS1 was the only polymorphism with genotype x time interaction in HR over the three study phases (P = 0.04, RANOVA). None of the polymorphisms presented genotype x time interaction in SAP or DAP responses (P > 0.10, RANOVA). In all subjects at rest, the Ser49Gly polymorphism of ADRB1 tended (P = 0.06, ANOVA) to differentiate HR. Arg389Gly polymorphism of ADRB1 affected maximal SAP during exercise (P = 0.04, ANOVA) and the change in SAP from rest to maximal (P = 0.03, ANOVA). Arg389 homozygotes, particularly men, were less likely to have ventricular extrasystoles during the exercise (odds ratio = 0.68, 95% confidence interval = 0.51-0.91, P = 0.009, and odds ratio = 0.60, 95% confidence interval = 0.42-0.86, P = 0.006, respectively) than did Gly389 carriers. In conclusion, polymorphisms examined appear to have modulatory effects on hemodynamics in a clinical exercise test setting. However, the effects in absolute numbers were minor and clinically possibly insignificant.

    Journal of applied physiology (Bethesda, Md. : 1985) 2006;100;2;507-11

  • GNAS1 T393C polymorphism and survival in patients with sporadic colorectal cancer.

    Frey UH, Alakus H, Wohlschlaeger J, Schmitz KJ, Winde G, van Calker HG, Jöckel KH, Siffert W and Schmid KW

    Institute of Pharmacology, University Hospital of Essen, Essen, Germany. Ulrich.Frey@uni-essen.de

    Purpose: Signaling via the G protein Galpha s pathway is linked to proapoptotic processes in cancer cell lines. We have recently shown an association between the GNAS1 T393C polymorphism and disease progression in patients with bladder cancer with homozygous TT genotypes displaying increased transcription of Galpha s and a more favorable clinical course compared with C-allele carriers.

    In the present study, 151 patients with sporadic colorectal cancer were retrospectively genotyped to examine a potential association between T393C genotypes and survival. Moreover, two other single-nucleotide polymorphisms in common haplotype blocks within the gene GNAS1 and their interaction with the T393C polymorphism were investigated.

    Results: The allele frequency in the patients group was not significantly different from that of healthy blood donors. Kaplan-Meier curves for overall survival (mean follow-up, 43 months) showed that in International Union Against Cancer (UICC) stages I to II, the 5-year survival rate was significantly higher in TT genotypes (87.8%) compared with TC (71.0%) and CC genotypes (50.0%; P = 0.009), whereas no genotype effect could be observed for UICC stages III to IV. In multivariate Cox proportional analysis the T393C polymorphism was an independent prognostic factor for survival. Homozygous CC patients were at highest risk for death (hazard ratio, 12.1; P = 0.006) compared with TT genotypes. Heterozygous patients had an intermediate risk compatible with a gene-dose effect. The two haplotype blocks investigated were not associated with clinical outcome.

    Conclusions: The results support the role of the T393C polymorphism as a marker for survival in patients with colorectal cancer stages I to II and in the identification of patients who may benefit from adjuvant chemotherapy.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2005;11;14;5071-7

  • Association between beta-adrenergic receptor polymorphisms and their G-protein-coupled receptors with body mass index and obesity in women: a report from the NHLBI-sponsored WISE study.

    Terra SG, McGorray SP, Wu R, McNamara DM, Cavallari LH, Walker JR, Wallace MR, Johnson BD, Bairey Merz CN, Sopko G, Pepine CJ and Johnson JA

    Department of Pharmacy Practice, University of Florida College of Pharmacy, Gainesville, FL 32610, USA.

    Objectives: The beta-adrenergic receptor (betaAR) genes are candidate genes for obesity because of their roles in energy homeostasis and promotion of lipolysis in human adipose tissue. Objective is to determine the association between obesity and polymorphisms in genes of the beta(1)AR (ADRB1), beta(2)AR (ADRB2), beta(3)AR (ADRB3), Gs protein alpha (GNAS1), to which all three beta-receptors couple and the G protein beta3 subunit (GNB3), to which beta(3)ARs couple.

    Design: A case-control genetic association study.

    Subjects: A total of 643 black or white women enrolled in Women's Ischemia Syndrome Evaluation (WISE) study.

    Measurements: Genotypes were determined by PCR with single primer extension. Associations between genotype and body mass index (BMI), waist-to-hip ratio (WHR), waist circumference, and obesity were made.

    Results: Polymorphisms in the three betaAR genes, GNAS1, and GNB3 were not associated with BMI, WHR, waist circumference, or obesity. Linear and logistic regression analyses found no contribution of either genotype or haplotype with anthropometric measurements or obesity.

    Conclusions: Our study suggests that among American women with suspected coronary heart disease, polymorphisms in the betaARs and their G-protein-coupled receptors do not contribute to increased BMI, WHR, waist circumference, or obesity. Given that 50% of all women die from coronary heart disease, and a higher percentage have heart disease during their lifetime, our results are likely generalizable to many American women.

    Funded by: NCRR NIH HHS: M01-RR00425; NHLBI NIH HHS: N01-HV68161, N01-HV68162, N01-HV68163, N01-HV68164, R03HL65729, U01-HL64924-01

    International journal of obesity (2005) 2005;29;7;746-54

  • The T393C polymorphism of the G alpha s gene (GNAS1) is a novel prognostic marker in bladder cancer.

    Frey UH, Eisenhardt A, Lümmen G, Rübben H, Jöckel KH, Schmid KW and Siffert W

    Institut für Pharmakologie, Universitätsklinikum, Essen, Hufelandstrasse 55, D-45122 Essen, Germany. Ulrich.Frey@uni-essen.de

    The G protein G(alpha)s pathway is linked to proapoptotic signaling in cancer cell lines. To assess the role of the GNAS1 locus encoding G(alpha)s as a genetic factor for disease progression of transitional cell carcinoma (TCC) of the bladder, we genotyped the synonymous T393C polymorphism in 254 patients with TCC (minor allele frequency: 0.43) to examine a potential association between genotypes and disease progression. Using Kaplan-Meier estimates to calculate 5-year probabilities of follow-up, we could show that progression-free survival, metastasis-free survival, and cancer-specific survival was significantly increased in TT genotypes (56%, 84%, 82%) compared with CC genotypes (35%, 53%, 58%). In multivariate Cox proportional hazard analysis, the T393C polymorphism was an independent prognostic factor for clinical outcome. Homozygous CC patients were at highest risk for progression [odds ratio (OR), 1.94; P = 0.020], metastasis (OR, 3.49; P = 0.005), and tumor-related death (OR, 2.49; P = 0.031) compared with TT genotypes. Heterozygous patients had an intermediate risk compatible with a gene-dose effect. Real-time PCR analysis of urothelial tumor tissue as well as adipose and heart tissue revealed that G(alpha)s mRNA expression was highest in TT genotypes, indicating a proapoptotic effect in these genotypes. In conclusion, the GNAS1 T393C status associated with differential G(alpha)s mRNA expression is a novel independent prognostic marker for clinical outcome supporting a functional role of G(alpha)s in bladder cancer progression.

    Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2005;14;4;871-7

  • Albright's hereditary osteodystrophy (pseudohypoparathyroidism type Ia): clinical case with a novel mutation of GNAS1.

    Garavelli L, Pedori S, Zanacca C, Caselli G, Loiodice A, Mantovani G, Ammenti A, Virdis R and Banchini G

    Department of Pediatrics, S. Maria Nuova Hospital, Reggio Emilia, Italy. garavelli.livia@asmn.re.it

    Albright's hereditary osteodystrophy is characterized by ectopic calcification and ossification, round face, short hands and feet with short terminal phalanges, short metacarpals (especially 4th and 5th) and absence of the 4th knuckle (brachydactyly type E). Here we describe a case that recently came to our attention of a girl suffering from seizures caused by hypocalcaemia, in which the clinical diagnosis of Albright's hereditary osteodystrophy and Pseudohypoparathyroidism (PHP) (Pseudohypoparathyroidism Ia) was confirmed by DNA molecular analysis. This analysis revealed a novel mutation of GNAS 1, resulting in the nonsense mutation of exon 13 (CAG-->TAG, codon 384). This result expands the spectrum of GNAS1 mutations associated with this disorder.

    Acta bio-medica : Atenei Parmensis 2005;76;1;45-8

  • Association of a GNAS1 gene variant with hypertension and diabetes mellitus.

    Yamamoto M, Abe M, Jin JJ, Wu Z, Tabara Y, Mogi M, Kohara K, Miki T and Nakura J

    Department of Geriatric Medicine, School of Medicine, Ehime University, Onsen-gun, Ehime, Japan.

    Previous studies have shown that the T allele of the GNAS1 T393C polymorphism is associated with poor responsiveness to beta-blockade and that the T393C polymorphism interacts with cigarette smoking and alcohol consumption in the pathogenesis of hypertension. Thus, the T393C polymorphism is likely to interact with beta-adrenoceptor (beta-AR) stimulation in the pathogenesis of hypertension. Although this interaction might be caused by a direct effect of Gs proteins on the cardiovascular system, it could also result from an indirect effect of Gs proteins mediated by glucose metabolism. Moreover, association studies are often irreproducible. We therefore examined the possible interaction between the T393C polymorphism and gamma-glutamyl transpeptidase (GGT), which is an established biomarker of alcohol consumption, in the association with glucose metabolism as well as with hypertension in a Japanese population. Genotyping for GNAS1 was performed by using the polymerase chain reaction-restriction fragment length polymorphism method in all 821 samples. The present study showed a significant interaction between the T393C polymorphism and GGT in the association with hypertension (p =0.033). This interaction was even more significant after adjustment for all confounding factors (p =0.0025). In contrast, analysis of the possible interaction of the T393C polymorphism with GGT in the association with diabetes mellitus or fasting plasma glucose failed to show a significant result. These results did not support the hypothesis that the interaction between the T393C polymorphism and GGT in the association with hypertension could be caused by an indirect effect of Gs proteins mediated by glucose metabolism.

    Hypertension research : official journal of the Japanese Society of Hypertension 2004;27;12;919-24

  • G protein polymorphisms do not predict weight loss and improvement of hypertension in severely obese patients.

    Potoczna N, Wertli M, Steffen R, Ricklin T, Lentes KU and Horber FF

    Klinik Hirslanden, Zürich, Switzerland.

    Both the gene encoding the alpha subunit of G stimulatory proteins (GNAS1) and the beta3 subunit gene (GNB3) of G proteins are associated with obesity and/or hypertension. Moreover, the TT/TC825 polymorphism of GNB3 predicts greater weight loss than the CC825 polymorphism in obese patients (mean body mass index, 35 kg/m2) undergoing a structured nonpharmacologic weight loss program. Gastric banding enforces a low-calorie diet by diminishing the need for volitional adherence. It is unknown whether these polymorphisms predict the variable weight loss in patients after bariatric surgery. Three hundred and four severely obese patients (mean +/- SEM age, 42 +/- 1 years; 245 women and 59 men; mean +/- SEM body mass index, 43.9 +/- 0.3 kg/m2) followed prospectively for at least 3 years after surgery were genotyped for the GNB3 C825T, G814A, and GNAS1 T393 polymorphisms. All analyses were performed blinded to the phenotypic characteristics of the study group. Frequencies of polymorphisms were comparable to those previously published. No polymorphism studied predicted 3-year weight loss or was associated with high blood pressure in severely obese patients after gastric banding. Multivariate analysis of potentially confounding factors such as reoperation rate or use of sibutramine or orlistat revealed similar results (P > 0.1). Regardless of the mechanism(s) involved for these discordant findings, GNB3 C825T, G814A, and GNAS1 T393C polymorphisms do not seem to be reliable predictors of long-term weight loss.

    Journal of gastrointestinal surgery : official journal of the Society for Surgery of the Alimentary Tract 2004;8;7;862-8; discussion 868

  • T393C polymorphism of GNAS1 associated with the autonomic nervous system in young, healthy Japanese subjects.

    Yasuda K, Matsunaga T, Moritani T, Nishikino M, Gu N, Yoshinaga M, Nagasumi K, Yamamura T, Aoki N and Tsuda K

    Department of Endocrinology, Metabolism and Diabetes Mellitus, Kinki University School of Medicine, Osaka, Japan.

    1. T393C polymorphism of the gene encoding the Gs-protein alpha-subunit (GNAS1) has been reported recently to be associated with hypertension in which dysfunctions of the autonomic nervous system (ANS) are closely involved. In the present study, the association of this polymorphism with ANS activity was investigated in young, healthy Japanese males. 2. Four hundred and one subjects were genotyped for the T393C polymorphism of GNAS1 by polymerase chain reaction-restriction fragment length polymorphism. Autonomic nervous system activity during supine rest and when standing was assessed in 137 subjects by electrocardiogram R-R interval power spectral analysis. 3. One hundred and fifty-four subjects (38.4%) were homozygous for the T allele (TT), 188 (46.9%) were heterozygous (TC) and 59 (14.7%) were homozygous for the C allele (CC). There were no significant differences as to genotype among the clinical characteristics investigated. In power spectral analysis of heart rate variability, the high-frequency component and parasympathetic nervous system (PNS) index during supine rest were significantly lower in TT and TC carriers than in CC carriers. Furthermore, the increase in heart rate and the responsiveness of sympathetic nervous system index and PNS index to postural change from supine rest to standing were significantly lower in TT and TC carriers than in CC carriers. 4. These observations suggest that the GNAS1 T393C polymorphism is associated with ANS activity in youth, so that it may be useful as a genetic marker for future pathogenesis of hypertension. Follow-up studies are necessary to clarify the prevalence rates of hypertension among 393T allele carriers in the present study.

    Clinical and experimental pharmacology & physiology 2004;31;9;597-601

  • Activating GNAS1 gene mutations in patients with premature thelarche.

    Román R, Johnson MC, Codner E, Boric MA, áVila A and Cassorla F

    Institute of Maternal and Child Research, San Borja Arriarán Clinical Hospital, School of Medicine, University of Chile, Santiago, Chile.

    Objective: To identify GNAS1 gene mutations in girls with exaggerated and/or chronic fluctuating thelarche for at least 1-year duration with no other signs of precocious puberty, skeletal dysplasia, or typical skin lesions of McCune-Albright syndrome.

    We studied the GNAS1 gene mutation by allele-specific polymerase chain reaction and enzymatic digestion in leukocyte DNA in 23 girls previously described.

    Results: Fluctuating thelarche was present in 14 girls and exaggerated thelarche was observed in 9. Molecular study revealed that 6 girls had a substitution of arginine by histidine in codon 201 (R201H [+]). Three R201H (+) girls reached their menarche at a mean chronologic age of 10.8 years and 9 of the R201H (-) girls at a mean age of 11 years.

    Conclusions: Activating mutations of GNAS1 gene may be observed in some girls with chronic fluctuating and/or exaggerated thelarche, without other classic signs of McCune-Albright syndrome.

    The Journal of pediatrics 2004;145;2;218-22

  • Activating Gsalpha mutations: analysis of 113 patients with signs of McCune-Albright syndrome--a European Collaborative Study.

    Lumbroso S, Paris F, Sultan C and European Collaborative Study

    Service d'Hormonologie, Hôpital Lapeyronie, Centre Hospitalier Universitaire (CHU) de Montpellier and Institut National de la Santé et de la Recherche Médicale, Montpellier, France 34295.

    McCune-Albright syndrome (MAS) is a sporadic disorder characterized by the classic triad of polyostotic fibrous dysplasia, café-au-lait skin pigmentation, and peripheral precocious puberty. It is due to postzygotic activating mutations of arginine 201 in the guanine-nucleotide-binding protein (G protein) alpha-subunit (Gsalpha), leading to a mosaic distribution of cells bearing constitutively active adenylate cyclase. MAS is heterogeneous: beyond the classic triad, a number of atypical or partial presentations have been reported. We present here the results of a systematic search for Gsalpha mutations in patients presenting with at least one of the signs of MAS, using a PCR-based sensitive method. We studied 113 patients (98 girls and 15 boys), 24% presenting the classic triad, 33% with two signs, and 40% with only one classic sign. Overall, the mutation was identified in 43% of the patients. When an affected tissue was available, the mutation was found in more than 90% of the patients, whatever the number of signs. Skin was a noteworthy exception because only three of the 11 skin samples were positive. The mutation was detected in 46% of blood samples in patients presenting the classic triad, whereas this figure fell to 21% and 8% in patients with two and one sign, respectively. Our results highlight the frequency of partial forms of MAS and the usefulness of sensitive techniques to confirm the diagnosis at the molecular level. It should be emphasized that we found the mutation in 33% of the 39 cases of isolated peripheral precocious puberty. This study has further widened the definition of MAS. Affections as clinically different as monostotic fibrous dysplasia, isolated peripheral precocious puberty, neonatal liver cholestasis, and the classic MAS all appear to be components of a wide spectrum of diseases based on the same molecular defect.

    The Journal of clinical endocrinology and metabolism 2004;89;5;2107-13

  • Progressive osseous heteroplasia resulting from a new mutation in the GNAS1 gene.

    Chan I, Hamada T, Hardman C, McGrath JA and Child FJ

    Department of Dermatology, St Mary's Hospital, London, UK. ien.chan@kcl.ac.uk

    Progressive osseous heteroplasia (OMIM 166350) is a rare autosomal dominant condition that presents in childhood as dermal ossification and may progress deeper to involve subcutaneous fat and connective tissue. Recently, paternally inherited inactivating mutations in the GNAS1 gene on chromosome 20q13 have been implicated in the pathogenesis, although sporadic cases have also been reported. We report a 9-year-old British Chinese girl with progressive osseous heteroplasia resulting from a de novo missense mutation (W281R) in the GNAS1 gene. She is of small stature (0.4th centile) and started to develop skin lesions at the age of 9 months. These have been confirmed histologically as osteoma cutis. She is of normal intelligence and development and has no dysmorphic features. The GNAS1 gene exhibits imprinting and maternally inherited mutations have previously been shown to result in Albright's hereditary osteodystrophy (OMIM 103580) with pseudohypothyroidism type 1a, whereas paternally inherited mutations result in progressive osseous heteroplasia or the Albright's hereditary osteodystrophy phenotype with pseudopseudohypothyroidism (OMIM 300800). With only nine mutations of the GNAS1 gene reported so far in progressive osseous heteroplasia, this new mutation helps to extend further the genotype-phenotype correlation.

    Clinical and experimental dermatology 2004;29;1;77-80

  • Thyroid carcinoma in the McCune-Albright syndrome: contributory role of activating Gs alpha mutations.

    Collins MT, Sarlis NJ, Merino MJ, Monroe J, Crawford SE, Krakoff JA, Guthrie LC, Bonat S, Robey PG and Shenker A

    Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-4320, USA. mc247k@nih.gov

    McCune-Albright syndrome (MAS) is defined by the triad of café-au-lait skin pigmentation, polyostotic fibrous dysplasia, and hyperfunctioning endocrinopathies, such as precocious puberty, hyperthyroidism, GH excess, and Cushing's syndrome. This disorder is caused by sporadic, postzygotic activating mutations in the GNAS1 gene, which codes for the G(s)alpha protein in the cAMP signaling cascade. Nodular and diffuse goiters (with and without hyperthyroidism), as well as benign thyroid nodules, have been reported in association with MAS. Herein we report two cases of thyroid carcinoma in patients with MAS. The first is a case of papillary thyroid cancer detected incidentally during a hemithyroidectomy for hyperthyroidism in a 14-yr-old girl. The second is one of a 41-yr-old woman with long-standing MAS and an enlarging thyroid nodule, which was diagnosed as a clear cell thyroid carcinoma, a rare variant of thyroid cancer. Molecular analysis revealed that foci of malignancy and adjacent areas of hyperplasia and some areas of normal thyroid harbored activating mutations of Arg(201) in the GNAS1 gene. These findings suggest that the infrequent development of thyroid carcinoma in MAS patients involves additional mutational or epigenetic events.

    Funded by: NCI NIH HHS: CA-78436

    The Journal of clinical endocrinology and metabolism 2003;88;9;4413-7

  • Cushing's syndrome secondary to adrenocorticotropin-independent macronodular adrenocortical hyperplasia due to activating mutations of GNAS1 gene.

    Fragoso MC, Domenice S, Latronico AC, Martin RM, Pereira MA, Zerbini MC, Lucon AM and Mendonca BB

    Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM-42, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil 01060-970. mariofragoso@uol.com.br

    ACTH-independent macronodular adrenal hyperplasia (AIMAH) is an uncommon cause of Cushing's syndrome characterized by bilateral nodular adrenocortical hyperfunction in the presence of suppressed ACTH levels. We investigated whether activating mutations in the ACTH receptor (MC2-R) or G(s alpha) (GNAS1) genes might be involved in AIMAH genesis. Five women with Cushing's syndrome due to AIMAH, confirmed by histological studies, and no signs of McCune-Albright syndrome were selected for molecular analysis of these genes. The single exon of the MC2-R gene and exons 8 and 9 of the GNAS1 gene were amplified by PCR in genomic DNA from adrenal nodules and peripheral blood. Direct sequencing revealed only MC2-R wild-type sequences. GNAS1 PCR products at denaturing gradient gel electrophoresis revealed abnormal migration patterns in adrenal tissues of three patients. Automatic sequencing showed two different activating mutations at codon Arg(201) of GNAS1, a substitution by histidine in two cases and by serine in one case. In conclusion, we found two different gsp mutations in three patients with Cushing's syndrome due to AIMAH, and we speculate whether they belong to the spectrum of McCune-Albright syndrome or whether these are the first reported cases of AIMAH due to gsp mutations.

    The Journal of clinical endocrinology and metabolism 2003;88;5;2147-51

  • Molecular analysis of the GNAS1 gene for the correct diagnosis of Albright hereditary osteodystrophy and pseudohypoparathyroidism.

    De Sanctis L, Romagnolo D, Olivero M, Buzi F, Maghnie M, Scirè G, Crino A, Baroncelli GI, Salerno M, Di Maio S, Cappa M, Grosso S, Rigon F, Lala R, De Sanctis C and Dianzani I

    Department of Pediatric Sciences, 94, Piazza Polonia, 10126 Torino, Italy; ldesanct@pediatria.unito.it

    Pseudohypoparathyroidism (PHP) is a heterogeneous disease characterized by PTH resistance and classified as types Ia, Ib, Ic, and II, according to its different pathogenesis and phenotype. PHP-Ia patients show Gsalpha protein deficiency, PTH resistance, and typical Albright hereditary osteodystrophy (AHO). Heterozygous mutations in the GNAS1 gene encoding the Gsalpha protein have been identified both in PHP-Ia and in pseudopseudohypoparathyroidism (PPHP), a disorder with isolated AHO. A single GNAS1 mutation may be responsible for both PHP-Ia and PPHP in the same family when inherited from the maternal and the paternal allele, respectively, suggesting that GNAS1 is an imprinted gene. To evaluate whether molecular diagnosis is a useful tool to characterize AHO and PHP when testing for Gsalpha activity and PTH resistance is not available, we have performed GNAS1 mutational analysis in 43 patients with PTH resistance and/or AHO. Sequencing of the whole coding region of the GNAS1 gene identified 11 mutations in 18 PHP patients, eight of which have not been reported previously. Inheritance was ascertained in 13 cases, all of whom had PHP-Ia: the mutated alleles were inherited from the mothers, who had AHO (PPHP), consistent with the proposed imprinting mechanism. GNAS1 molecular analysis confirmed the diagnosis of PHP-Ia and PPHP in the mutated patients. Our results stress the usefulness of this approach to obtain a complete diagnosis, expand the GNAS1 mutation spectrum, and illustrate the wide mutation heterogeneity of PHP and PHP-Ia.

    Pediatric research 2003;53;5;749-55

  • A new heterozygous mutation (L338N) in the human Gsalpha (GNAS1) gene as a cause for congenital hypothyroidism in Albright's hereditary osteodystrophy.

    Pohlenz J, Ahrens W and Hiort O

    Children's Hospital, Johannes Gutenberg-University, Langenbeckstrasse 1, D-55101 Mainz, Germany. pohlenz@mail.uni-mainz.de

    Objective: To identify the molecular defect by which psychomotor retardation is caused in two brothers with congenital hypothyroidism who received adequate treatment with l-thyroxine.

    A six-year-old boy presented with psychomotor retardation and congenital primary hypothyroidism (CH). The patient had a normal blood thyrotrophin (TSH) level on neonatal screening, but low total serum thyroxine and triiodothyronine concentrations prompting thyroid hormone substitution shortly after birth. Nevertheless, psychomotor development was retarded and the patient underwent further investigation. Typical features of Albright's hereditary osteodystrophy (AHO) such as round face, obesity, and shortened 1st, 4th and 5th metacarpals were found.

    Further investigation confirmed AHO with pseudohypoparathyroidism (PHP) type Ia. The boy had a mild resistance to parathyroid hormone and a reduced adenylyl cyclase stimulating protein (Gsalpha) activity in erythrocytes. DNA analysis detected a new heterozygous mutation (L338N) in the Gsalpha protein (GNAS1) gene. This mutation was also present in the patient's brother who had similar features and was also treated with thyroid hormone because of CH, and in the phenotypically normal-looking mother who had a normal calcium metabolism but a reduced Gsalpha protein activity in erythrocytes suggestive of pseudopseudohypoparathyroidism.

    Conclusion: In patients with CH, in whom the neurological outcome is poor even under adequate thyroid hormone substitution, PHP Ia may be suspected, especially when symptoms of AHO are present.

    European journal of endocrinology 2003;148;4;463-8

  • Pubertal development in patients with McCune-Albright syndrome or pseudohypoparathyroidism.

    de Sanctis C, Lala R, Matarazzo P, Andreo M and de Sanctis L

    Department of Pediatric Endocrinology, Regina Margherita Children 's Hospital, Turin, Italy. malattierare@libero.it

    Gain or loss of function mutations of the GNAS1 gene lead to McCune-Albright syndrome (MAS) or pseudohypoparathyroidism Ia (PHP-Ia), respectively. Patients with MAS, caused by a post-zygotic missense mutation leading to constitutive activation of Gs alpha, suffer from gonadotropin-independent precocious puberty, and delayed or incomplete sexual development and reproductive dysfunction is found in women with PHP-Ia, an inherited disorder caused by deficient expression or function of the Gs alpha protein. In females with MAS, 50% developed precocious puberty by the age of 4 years, the remaining between 4 and 8 years. Peripheral precocious puberty is often atypical and characterized by alternate periods of rapid progression and regression of pubertal development; menstrual bleeding may occur before breast development. Ovarian cyst growth and regression is often described as a sign of ovarian follicle hyperactivation. Notwithstanding this clinical heterogeneity, a subset of patients with MAS develop relentlessly progressive precocious puberty ultimately resulting in premature epiphyseal fusion and reduced adult stature. Long-term information on reproductive function has been obtained in females: some patients had regular menses without ovarian cysts on pelvic US scan, whereas others were oligomenorrheic and showed recurrent ovarian cysts. In males with MAS, precocious puberty occurred in three patients between 4 and 9 years of age. In one patient, long-term follow-up demonstrated normal plasma testosterone and gonadotropin values at the age of 17 years. On testicular sonography, multiple hyperechogeneic spots were found in both testicles (snow-storm appearance). Female patients with PHP-Ia were oligomenorrheic or amenorrheic; more than half had delayed or incomplete sexual development, They were mildly hypoestrogenic with normal to slightly elevated serum gonadotropin levels. These clinical and biochemical findings indicate partial resistance of the theca and granulosa cells of the ovary to gonadotropins due to deficient Gs alpha activity. Responsiveness might be sufficient to promote some degree of follicular development and steroid secretion, but insufficient to induce ovulation

    Journal of pediatric endocrinology & metabolism : JPEM 2003;16 Suppl 2;293-6

  • Constitutional deletion of chromosome 20q in two patients affected with albright hereditary osteodystrophy.

    Aldred MA, Aftimos S, Hall C, Waters KS, Thakker RV, Trembath RC and Brueton L

    Division of Medical Genetics, University of Leicester, and Department of Molecular Genetics, University Hospitals of Leicester NHS Trust, Leicester, UK. maldred@hgmp.mrc.ac.uk

    Albright hereditary osteodystrophy (AHO) results from heterozygous inactivation of G(s)alpha, encoded by the GNAS1 locus on the distal long arm of chromosome 20. This autosomal dominant condition is characterized by short stature, obesity, shortening of the metacarpals and metatarsals, and variable mental retardation and may also include end-organ resistance to multiple hormones. Small insertions and deletions or point mutations of GNAS1 are found in approximately 80% of patients with AHO. The remainder may be accounted for by larger genomic rearrangements, but none have been reported to date. We now describe two patients with constitutional 20q deletions and features of AHO. Such deletions are rare in the published literature and have not previously been associated with AHO. Molecular genetic analysis confirmed complete deletion of GNAS1 in both patients. Parental origin could be determined in both cases and provides further support for the parent-of-origin effect on the biochemical status of patients with AHO.

    American journal of medical genetics 2002;113;2;167-72

  • Familial ACTH-independent Cushing's syndrome with bilateral macronodular adrenal hyperplasia clinically affecting only female family members.

    Nies C, Bartsch DK, Ehlenz K, Wild A, Langer P, Fleischhacker S and Rothmund M

    Department of General Surgery, Klinik für Visceral-, Thorax- und Gefässchirurgue, Philipps-University Marburg, Germany. nies@mailer.uni-marburg.de

    Primary adrenal hyperplasia, which may occur as a familial disorder, is a rare cause of ACTH-independent Cushing's syndrome. In most of these cases the underlying pathology is primary adrenocortical micronodular dysplasia. Very few cases of familial Cushing's syndrome due to primary macronodular adrenal hyperplasia have been described. We report a family with seven affected family members. The pedigree indicates an autosomal dominantly inherited disorder. Interestingly only female family members developed the clinically apparent syndrome. The only available obligatory male gene carrier failed to adequately suppress his plasma cortisol level on overnight dexamethasone suppression test. His adrenal glands showed nodular enlargement on abdominal computed tomographic imaging. Screening of the MEN 1 gene and genetic analysis of the hot spot regions of the GNAS 1 (codons 201 and 227) and GNAI 2 (codons 179 and 205) genes did not show any mutations in the constitutional DNA or the adrenal tissue DNA of the index patient. In conclusion, this family is the largest kindred reported in the literature with ACTH-independent Cushing's syndrome due to autosomal dominant inherited macronodular adrenocortical hyperplasia. Four currently alive and affected family members in two generations and further careful observation of the yet unaffected members of the third available generation might offer the opportunity to identify the still unknown gene defect in the future.

    Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association 2002;110;6;277-83

  • Mutational analysis of the GNAS1 exons encoding the stimulatory G protein in five patients with pseudohypoparathyroidism type 1a.

    Lim SH, Poh LK, Cowell CT, Tey BH and Loke KY

    Department of Paediatrics, National University of Singapore, Singapore.

    We analyzed the GNAS1 gene in five patients with pseudohypoparathyroidism type 1a (PHP1a) by performing polymerase chain reaction, followed by sequencing all 13 exons of the gene, single-stranded conformational polymorphism (SSCP) or heteroduplex analysis (HD). Three novel mutations were discovered: (1) a de novo 3 bp insertion of CTG in codon 47 of exon 1; (2) a missense mutation 1103T in exon 4; and (3) a de novo mutation of Arg280Gly in exon 10. Two other mutations, previously described in the literature, include: (1) a de novo 4 bp deletion (deltaGACT) involving codons 189 and 190 in exon 7, and (2) a deletion of a cytosine nucleotide at codon 115 in exon 5. We conclude that mutational analysis of the GNAS1 gene is a strong supportive tool for the diagnosis of PHP1a, and is a useful adjunct to the synthetic parathyroid hormone infusion test for PTH resistance.

    Journal of pediatric endocrinology & metabolism : JPEM 2002;15;3;259-68

  • Paternally inherited inactivating mutations of the GNAS1 gene in progressive osseous heteroplasia.

    Shore EM, Ahn J, Jan de Beur S, Li M, Xu M, Gardner RJ, Zasloff MA, Whyte MP, Levine MA and Kaplan FS

    Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia 19104-6018, USA. shore@mail.med.upenn.edu

    Background: Progressive osseous heteroplasia (POH), an autosomal dominant disorder, is characterized by extensive dermal ossification during childhood, followed by disabling and widespread heterotopic ossification of skeletal muscle and deep connective tissue. Occasional reports of mild heterotopic ossification in Albright's hereditary osteodystrophy (AHO) and a recent report of two patients with AHO who had atypically extensive heterotopic ossification suggested a common genetic basis for the two disorders. AHO is caused by heterozygous inactivating mutations in the GNAS1 gene that result in decreased expression or function of the alpha subunit of the stimulatory G protein (Gsalpha) of adenylyl cyclase.

    Methods: We tested the hypothesis that GNAS1 mutations cause POH, using the polymerase chain reaction to amplify GNAS1 exons and exon-intron boundaries in 18 patients with sporadic or familial POH.

    Results: Heterozygous inactivating GNAS1 mutations were identified in 13 of the 18 probands with POH. The defective allele in POH is inherited exclusively from fathers, a result consistent with a model of imprinting for GNAS1. Direct evidence that the same mutation can cause either POH or AHO was observed within a single family, in which the phenotype correlated with the parental origin of the mutant allele.

    Conclusions: Paternally inherited inactivating GNAS1 mutations cause POH. This finding extends the range of phenotypes derived from haplo insufficiency of GNAS1, provides evidence that imprinting is a regulatory mechanism for GNAS1 expression, and suggests that Gsalpha is a critical negative regulator of osteogenic commitment in nonosseous connective tissues.

    Funded by: NIAMS NIH HHS: R01-AR41916, R01-AR46831; NIDDK NIH HHS: R01-DK34281

    The New England journal of medicine 2002;346;2;99-106

  • GNAS1 lesions in pseudohypoparathyroidism Ia and Ic: genotype phenotype relationship and evidence of the maternal transmission of the hormonal resistance.

    Linglart A, Carel JC, Garabédian M, Lé T, Mallet E and Kottler ML

    Department of Pediatric Endocrinology, Groupe Hospitalier Cochin-Saint Vincent de Paul, Assisvance Publique-Hôpitaux de Paris, 75014 Paris, France.

    We conducted clinical and biological studies including screening for mutations in the gene encoding the alpha subunit of G(s) (GNAS1) in 30 subjects (21 unrelated families) with Albright's hereditary osteodystrophy (AHO), pseudohypoparathyroidism (PHP); and decreased erythrocyte G(s) activity (PHP-Ia; n = 19); AHO and decreased erythrocyte G(s) activity (isolated AHO; n = 10); or AHO, hormonal resistance, and normal erythrocyte G(s) activity (PHP-Ic; n = 1). A heterozygous GNAS1 gene lesion was found in 14 of 17 PHP-Ia index cases (82%), including 11 new mutations and a mutational hot-spot involving codons 189-190 (21%). These lesions lead to a truncated protein in all but three cases with missense mutations R280K, V159M, and D156N. In the patient diagnosed with PHP-Ic, G(s)alpha protein was shortened by just four amino acids, a finding consistent with the conservation of G(s) activity in erythrocytes and the loss of receptor contact. No GNAS1 lesions were found in individuals with isolated AHO that were not relatives to PHP-Ia patients (n = 5). Intrafamilial segregation analyses of the mutated GNAS1 allele in nine PHP-Ia patients established that the mutation had either occurred de novo on the maternal allele (n = 4) or had been transmitted by a mother with a mild phenotype (n = 5). This finding is consistent with an imprinting of GNAS1 playing a role in the clinical phenotype of loss of function mutations and with a functional maternal GNAS1 allele having a predominant role in preventing the hormonal resistance of PHP-Ia.

    The Journal of clinical endocrinology and metabolism 2002;87;1;189-97

  • Searching for Arg201 mutations in the GNAS1 gene in Italian patients with McCune-Albright syndrome.

    de Sanctis L, Romagnolo D, Greggio N, Genitori L, Lala R and de Sanctis C

    Department of Pediatrics, University of Torino, Regina Margherita Children's Hospital, Italy. ldesanct@pediatria.unito.it

    McCune-Albright syndrome (MAS) is a rare disease caused by somatic postzygotic mutations at Arg201 in the GNAS1 gene that encodes for the Gsalpha protein. Arg201 mutations are gain-of-function mutations in affected tissues (including bone, skin, endocrine glands and other tissues) that result in the activation of cAMP. We used a polymerase chain reaction(PCR)-based technique for the selective enrichment and analysis of the Arg201 mutant allele in 27 different tissues from 24 Italian patients with one or more signs of MAS. Arg201 mutations were identified in 13 different tissues (48.1%) from 11 patients (45.8%). Mutation detection rates differed across the various types of tissue samples, and the mutation was not always found in every tissue sample from the same patient. To overcome problems in the analysis of mutations in somatic mosaicism, as occurs in MAS, a highly sensitive molecular technique should be applied, the most appropriate tissue source selected, and various affected tissues from the same patient analyzed.

    Journal of pediatric endocrinology & metabolism : JPEM 2002;15 Suppl 3;883-9

  • Analysis of the GNAS1 gene in Albright's hereditary osteodystrophy.

    Ahrens W, Hiort O, Staedt P, Kirschner T, Marschke C and Kruse K

    Department of Pediatrics, Medical University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany. ahrens@paedia.ukl.mu-luebeck.de

    Albright's hereditary osteodystrophy (AHO) is characterized by phenotypic signs that typically include brachydactyly and sc calcifications occurring with or without hormone resistance toward PTH or other hormones such as thyroid hormone or gonadotropins. Different inactivating mutations of the gene GNAS1 encoding Gsalpha lead to a reduced Gsalpha protein activity in patients with AHO and pseudohypoparathyroidism type Ia or without resistance to PTH (pseudopseudohypoparathyroidism). We investigated 29 unrelated patients with AHO and pseudohypoparathyroidism type Ia or pseudopseudohypoparathyroidism and their affected family members performing functional and molecular genetic analysis of Gsalpha. In vitro determination of Gsalpha protein activity in erythrocyte membranes was followed by the investigation of the whole coding region of the GNAS1 gene using PCR, nonisotopic single strand conformation analysis, and direct sequencing of the PCR products. All patients showed a reduced Gsalpha protein activity (mean 59% compared with healthy controls). In 21/29 (72%) patients, 15 different mutations in GNAS1 including 11 novel mutations were detected. In addition we add five unrelated patients with a previously described 4 bp deletion in exon 7 (Delta GACT, codon 189/190), confirming the presence of a hot spot for loss of function mutations in GNAS1. In eight patients, no molecular abnormality was found in the GNAS1 gene despite a functional defect of Gsalpha. We conclude that biochemical and molecular analysis of Gsalpha and its gene GNAS1 can be valuable tools to confirm the diagnosis of AHO. However, in some patients with reduced activity of Gsalpha, the molecular defect cannot be detected in the exons encoding the common form of Gsalpha.

    The Journal of clinical endocrinology and metabolism 2001;86;10;4630-4

  • Genetic variation of the extra-large stimulatory G protein alpha-subunit leads to Gs hyperfunction in platelets and is a risk factor for bleeding.

    Freson K, Hoylaerts MF, Jaeken J, Eyssen M, Arnout J, Vermylen J and Van Geet C

    Center for Molecular and Vascular Biology, University Hospital Gasthuisberg, University of Leuven, Belgium.

    Alternatively spliced GNAS1 and XL-GNAS1, encoding respectively the stimulatory G-protein alpha-subunit (Gsalpha) and the extra-large stimulatory G-protein alpha-subunit (XLsalpha), are located on the imprinted chromosomal region 20q13.12-13. We presently report a functional polymorphism in the imprinted XL-GNAS1 gene. In three patients, a 36 bp insertion and two basepair substitutions flanking this insertion were found in the paternally inherited XL-GNAS1 exon 1. They clinically manifest an enhanced trauma-related bleeding tendency and a variable degree of mental retardation. A platelet aggregation inhibition test to evaluate Gs function was developed. Their platelets display Gs hyperfunction and an enhanced cAMP generation upon stimulation of Gs-coupled receptors. The prevalence of the XLsalpha insertion in a normal control group was 2.2%. Normal controls, inheriting the insertion maternally, had a normal platelet Gs activity, whereas controls inheriting the insertion paternally had increased inducible platelet Gs activity, defining the insertion as a functional polymorphism. This paternally inherited XLsalpha insertion represents a new genetic cause of an inherited bleeding tendency, although to a variable degree.

    Thrombosis and haemostasis 2001;86;3;733-8

  • [Albright hereditary osteodystrophy: identification of a novel mutation in a family].

    Bastida Eizaguirre M, Iturbe Ortiz De Urbina R, Arto Urzainqui M, Ezquerra Larreina R and Escalada San Martín J

    Servicios de Pediatría Endocrinología. Hospital Santiago Apóstol. Vitoria. mbastida@hsan.osakidetza.net

    Studies to detect mutations in the GNAS1 gene were performed in a male patient with features of Albright hereditary osteodystrophy and resistance of target tissues to parathyroid hormone (Pseudohypoparathyroidism Ia). The same investigations were carried out in the patient's mother who showed somatic features of Albright's hereditary osteodystrophy and brachymetacarpia without resistance to parathyroid hormone (Pseudopseudohypoparathyroidism). A point mutation designated c.794GA (R265H) in exon 10 of GNAS1 was identified in DNA from the patient and his mother. This novel mutation in exon 10 of GNA

    Anales espanoles de pediatria 2001;54;6;598-600

  • Mazabraud syndrome in two patients: clinical overlap with McCune-Albright syndrome.

    Faivre L, Nivelon-Chevallier A, Kottler ML, Robinet C, Khau Van Kien P, Lorcerie B, Munnich A, Maroteaux P, Cormier-Daire V and LeMerrer M

    Centre de Génétique, Hôpital d'Enfants, Dijon, France.

    Mazabraud syndrome is a rare sporadic disorder, mainly characterized by bone fibrous dysplasia and intramuscular myxomas. We report here two new cases of Mazabraud syndrome. One of our patients (Patient 1) also had café-au-lait spots and multinodular goiter suggestive of McCune-Albright syndrome. We review the 37 previously reported cases with Mazabraud syndrome and discuss the 6/37 patients with criteria of Mazabraud and McCune-Albright syndromes. Based on the clinical overlap between the two syndromes, we tested the GNAS1 gene in blood leukocytes and skin fibroblasts of Patient 1, but found no evidence of an activating mutation in the GNAS1 gene.

    American journal of medical genetics 2001;99;2;132-6

  • Study of the multiple endocrine neoplasia type 1, growth hormone-releasing hormone receptor, Gs alpha, and Gi2 alpha genes in isolated familial acromegaly.

    Jorge BH, Agarwal SK, Lando VS, Salvatori R, Barbero RR, Abelin N, Levine MA, Marx SJ and Toledo SP

    Endocrine Genetics Unit (LIM-25) and Hormone and Molecular Genetics Laboratory, Endocrinology Section, Department of Medicine, University of Sao Paulo School of Medicine, Sao Paulo SP 01246-903, Brazil. beatrizjorge@hotmail.com

    Familial acromegaly may occur as an isolated pituitary disorder or as a feature of hereditary syndromes, such as multiple endocrine neoplasia type 1 (MEN1) or the Carney complex. Herein, we characterized a newly identified kindred with isolated acromegaly and searched for germline mutation in genes that have been associated with endocrine tumors [i.e. MEN1, Gs alpha (GNAS1), and Gi2 alpha (GNAI2)], as well as the GHRH receptor (GHRH-R) gene. Genomic DNA was used to amplify exons 2-10 of MEN1, followed by dideoxy fingerprinting mutation analysis and direct sequencing. The GHRH-R gene was analyzed via direct sequencing of PCR-amplified fragments representing the coding exons and intron-exon junctions. To exclude mutation at hot spot areas of GNAS1 and GNAI2, exons 8 and 9 of GNAS1 and exons 5 and 6 of GNAI2 were amplified and screened for mutation via denaturing gradient gel electrophoresis. No mutations were detected in any of the four genes. The present data extend prior reports of the absence of mutation in MEN1, GHRH-R, and GNAS1 and describe the first family with isolated acromegaly in which germline mutation in GNAI2 has been searched.

    Funded by: NCRR NIH HHS: 3-M01-RR-000052

    The Journal of clinical endocrinology and metabolism 2001;86;2;542-4

  • Selective resistance to parathyroid hormone caused by a novel uncoupling mutation in the carboxyl terminus of G alpha(s). A cause of pseudohypoparathyroidism type Ib.

    Wu WI, Schwindinger WF, Aparicio LF and Levine MA

    Division of Pediatric Endocrinology, Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.

    G(s) is a heterotrimeric (alpha, beta, and gamma chains) G protein that couples heptahelical plasma membrane receptors to stimulation of adenylyl cyclase. Inactivation of one GNAS1 gene allele encoding the alpha chain of G(s) (G alpha(s)) causes pseudohypoparathyroidism type Ia. Affected subjects have resistance to parathyroid hormone (PTH) and other hormones that activate adenylyl cyclase plus somatic features termed Albright hereditary osteodystrophy. By contrast, subjects with pseudohypoparathyroidism type Ib have hormone resistance that is limited to PTH and lack Albright hereditary osteodystrophy. The molecular basis for pseudohypoparathyroidism type Ib is unknown. We analyzed the GNAS1 gene for mutations using polymerase chain reaction to amplify genomic DNA from three brothers with pseudohypoparathyroidism type Ib. We identified a novel heterozygous 3-base pair deletion causing loss of isoleucine 382 in the three affected boys and their clinically unaffected mother and maternal grandfather. This mutation was absent in other family members and 15 additional unrelated subjects with pseudohypoparathyroidism type Ib. To characterize the signaling properties of the mutant G alpha(s), we used site-directed mutagenesis to introduce the isoleucine 382 deletion into a wild type G alpha(s) cDNA, transfected HEK293 cells with either wild type or mutant G alpha(s) cDNA, plus cDNAs encoding heptahelical receptors for PTH, thyrotropic hormone, or luteinizing hormone, and we measured cAMP production in response to hormone stimulation. The mutant G alpha(s) protein was unable to interact with the receptor for PTH but showed normal coupling to the other coexpressed heptahelical receptors. These results provide evidence of selective uncoupling of the mutant G alpha(s) from PTH receptors and explain PTH-specific hormone resistance in these three brothers with pseudohypoparathyroidism type Ib. The absence of PTH resistance in the mother and maternal grandfather who carry the same mutation is consistent with current models of paternal imprinting of the GNAS1 gene.

    Funded by: NCRR NIH HHS: RR0035; NIDDK NIH HHS: DK34281

    The Journal of biological chemistry 2001;276;1;165-71

  • Deficiency of the alpha-subunit of the stimulatory G protein and severe extraskeletal ossification.

    Eddy MC, Jan De Beur SM, Yandow SM, McAlister WH, Shore EM, Kaplan FS, Whyte MP and Levine MA

    Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, Missouri 63131, USA.

    Progressive osseous heteroplasia (POH) is a rare disorder characterized by dermal ossification beginning in infancy followed by increasing and extensive bone formation in deep muscle and fascia. We describe two unrelated girls with typical clinical, radiographic, and histological features of POH who also have findings of another uncommon heritable disorder, Albright hereditary osteodystrophy (AHO). One patient has mild brachydactyly but no endocrinopathy, whereas the other manifests brachydactyly, obesity, and target tissue resistance to thyrotropin and parathyroid hormone (PTH). Levels of the alpha-subunit of the G protein (Gsalpha) were reduced in erythrocyte membranes from both girls and a nonsense mutation (Q12X) in exon 1 of the GNAS1 gene was identified in genomic DNA from the mildly affected patient. Features of POH and AHO in two individuals suggest that these conditions share a similar molecular basis and pathogenesis and that isolated severe extraskeletal ossification may be another manifestation of Gsalpha deficiency.

    Funded by: NIAMS NIH HHS: 2R01-AR41916-04; NIDDK NIH HHS: DK 34281; PHS HHS: GCRC 00055

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2000;15;11;2074-83

  • GNAS1 mutation and Cbfa1 misexpression in a child with severe congenital platelike osteoma cutis.

    Yeh GL, Mathur S, Wivel A, Li M, Gannon FH, Ulied A, Audi L, Olmstead EA, Kaplan FS and Shore EM

    Department of Orthopaedic Surgery, University of Pennsylvania, School of Medicine, Philadelphia 19104-6081, USA.

    We evaluated a 7-year-old girl with severe platelike osteoma cutis (POC), a variant of progressive osseous heteroplasia (POH). The child had congenital heterotopic ossification of dermis and subcutaneous fat that progressed to involve deep skeletal muscles of the face, scalp, and eyes. Although involvement of skeletal muscle is a prominent feature of POH, heterotopic ossification has not been observed in the head, face, or extraocular muscles. The cutaneous ossification in this patient was suggestive of Albright hereditary osteodystrophy (AHO); however, none of the other characteristic features of AHO were expressed. Inactivating mutations of the GNAS1 gene, which encodes the alpha-subunit of the stimulatory G protein of adenylyl cyclase, is the cause of AHO. Mutational analysis of GNAS1 using genomic DNA of peripheral blood and of lesional and nonlesional tissue from our patient revealed a heterozygous 4-base pair (bp) deletion in exon 7, identical to mutations that have been found in some AHO patients. This 4-bp deletion in GNAS1 predicts a protein reading frameshift leading to 13 incorrect amino acids followed by a premature stop codon. To investigate pathways of osteogenesis by which GNAS1 may mediate its effects, we examined the expression of the obligate osteogenic transcription factor Cbfa1/RUNX2 in lesional and uninvolved dermal fibroblasts from our patient and discovered expression of bone-specific Cbfa1 messenger RNA (mRNA) in both cell types. These findings document severe heterotopic ossification in the absence of AHO features caused by an inactivating GNAS1 mutation and establish the GNAS1 gene as the leading candidate gene for POH.

    Funded by: NIAMS NIH HHS: 1-RO1-AR46831-01, 2-RO1-AR41916-04, R01 AR041916

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2000;15;11;2063-73

  • Mutational analysis of GNAS1 in patients with pseudohypoparathyroidism: identification of two novel mutations.

    Mantovani G, Romoli R, Weber G, Brunelli V, De Menis E, Beccio S, Beck-Peccoz P and Spada A

    Ospedale Maggiore IRCCS, Institute of Endocrine Sciences, University of Milan, Italy.

    Pseudohypoparathyroidism (PHP) refers to two major variants that generally coexist in the same family, PHP type Ia (PHP Ia), in which both PTH resistance and a constellation of physical features, termed Albright's hereditary osteodystrophy (AHO), are present, and pseudopseudohypoparathyroidism (PPHP), in which AHO occurs without PTH resistance. Most patients with PHP Ia show a partial deficiency (50%) of Gs activity, due to loss of function mutations in Gsalpha gene (GNAS1). The present study reports clinical, biochemical, and molecular data of 8 unrelated families with PHP Ia and PPHP. The 13 exons of GNAS1 were screened for mutations by PCR and direct sequencing of the amplified products. We detected heterozygous mutations in the affected members of the 4 families in which PHP Ia was present. In 2 families 2 previously reported deletions in exons 5 and 7 were found, whereas in the other 2 families, 2 novel frameshift deletions were identified in exons 1 and 11, causing a premature stop codon in the mutant allele. No mutation was detected in the families in which PPHP was the only clinical manifestation. In conclusion, we report the first mutational analysis of Italian patients with PHP Ia and PPHP, and we describe two novel deletions in GNAS1. Furthermore, we confirm that these mutations cannot be detected in families with isolated PPHP, suggesting that these forms of AHO are genetically distinct from PHP Ia.

    The Journal of clinical endocrinology and metabolism 2000;85;11;4243-8

  • Mutations of the GNAS1 gene, stromal cell dysfunction, and osteomalacic changes in non-McCune-Albright fibrous dysplasia of bone.

    Bianco P, Riminucci M, Majolagbe A, Kuznetsov SA, Collins MT, Mankani MH, Corsi A, Bone HG, Wientroub S, Spiegel AM, Fisher LW and Robey PG

    Dipartimento di Medicina Sperimentale, Università dell'Aquila, Italy.

    Activating missense mutations of the GNAS1 gene, encoding the alpha subunit of the stimulatory G protein (Gs), have been identified in patients with the McCune-Albright syndrome (MAS; characterized by polyostotic fibrous dysplasia, café au lait skin pigmentation, and endocrine disorders). Because fibrous dysplasia (FD) of bone also commonly occurs outside of the context of typical MAS, we asked whether the same mutations could be identified routinely in non-MAS FD lesions. We analyzed a series of 8 randomly obtained, consecutive cases of non-MAS FD and identified R201 mutations in the GNAS1 gene in all of them by sequencing cDNA generated by amplification of genomic DNA using a standard primer set and by using a novel, highly sensitive method that uses a protein nucleic acid (PNA) primer to block amplification of the normal allele. Histologic findings were not distinguishable from those observed in MAS-related FD and included subtle changes in cell shape and collagen texture putatively ascribed to excess endogenous cyclic adenosine monophosphate (cAMP). Osteomalacic changes (unmineralized osteoid) were prominent in lesional FD bone. In an in vivo transplantation assay, stromal cells isolated from FD failed to recapitulate a normal ossicle; instead, they generated a miniature replica of fibrous dysplasia. These data provide evidence that occurrence of GNAS1 mutations, previously noted in individual cases of FD, is a common and perhaps constant finding in non-MAS FD. These findings support the view that FD, MAS, and nonskeletal isolated endocrine lesions associated with GNAS1 mutations represent a spectrum of phenotypic expressions (likely reflecting different patterns of somatic mosaicism) of the same basic disorder. We conclude that mechanisms underlying the development of the FD lesions, and hopefully mechanism-targeted therapeutic approaches to be developed, must also be the same in MAS and non-MAS FD.

    Funded by: Telethon: E.1029

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2000;15;1;120-8

  • Identification of two novel deletion mutations within the Gs alpha gene (GNAS1) in Albright hereditary osteodystrophy.

    Yu D, Yu S, Schuster V, Kruse K, Clericuzio CL and Weinstein LS

    Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

    Albright hereditary osteodystrophy (AHO) is a genetic disorder characterized by short stature, skeletal defects, and obesity. Within AHO kindreds, some affected family members have only the somatic features of AHO [pseudopseudohypoparathyroidism (PPHP)], whereas others have these features in association with resistance to multiple hormones that stimulate adenylyl cyclase within their target tissues [pseudohypoparathyroidism type Ia (PHP Ia)]. Affected members of most AHO kindreds (both those with PPHP and those with PHP Ia) have a partial deficiency of Gs alpha, the alpha-subunit of the G protein that couples receptors to adenylyl cyclase stimulation, and in a number of cases heterozygous loss of function mutations within the Gs alpha gene (GNAS1) have been identified. Using PCR with the attachment of a high melting domain (GC-clamp) and temperature gradient gel electrophoresis, two novel heterozygous frameshift mutations within GNAS1 were found in two AHO kindreds. In one kindred all affected members (both PHP Ia and PPHP) had a heterozygous 2-bp deletion in exon 8, whereas in the second kindred a heterozygous 2-bp deletion in exon 4 was identified in all affected members examined. In both cases the frameshift encoded a premature termination codon several codons downstream of the deletion. In the latter kindred affected members were previously shown to have decreased levels of GNAS1 messenger ribonucleic acid expression. These results further underscore the genetic heterogeneity of AHO and provides further evidence that PHP Ia and PPHP are two clinical presentations of a common genetic defect. Serial measurements of thyroid function in members of kindred 1 indicate that TSH resistance progresses with age and becomes more evident after the first year of life.

    The Journal of clinical endocrinology and metabolism 1999;84;9;3254-9

  • Association of the G(s)alpha gene with essential hypertension and response to beta-blockade.

    Jia H, Hingorani AD, Sharma P, Hopper R, Dickerson C, Trutwein D, Lloyd DD and Brown MJ

    Clinical Pharmacology Unit, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK. h.jiia@ucl.ac.uk

    We examined whether the GNAS1 locus, encoding the G(s) protein alpha-subunit (G(s)alpha), is implicated in the genetic causes of essential hypertension. A common silent polymorphism (ATT-->ATC, Ile(131)) was identified in exon 5 of the G(s)alpha gene by single-strand conformation polymorphism analysis and DNA sequencing. This polymorphism consists of the presence (+) or absence (-) of a restriction site for FokI. Only 1 other rare allele was found in the coding region; the high GC content of the 5' noncoding sequence prevented mutation scanning of the promoter region of the gene. There was a significant difference in frequency of the FokI alleles between 268 white hypertensives (FokI+:FokI-, 51%:49%) and a matched group of 231 control subjects (FokI+:FokI-, 58%:42%) (P=0.02). Multiple regression analysis showed that the FokI genotype was independently related to the level of untreated systolic blood pressure in 294 well-characterized white hypertensives (P=0.01) but not in normotensives. The influence of the FokI allele on blood pressure (BP) response to beta-blockade was examined in 114 of the patients randomly assigned to this class of drug. Significant differences in frequency of the FokI allele were observed in the good responders (FokI+:FokI-, 62.5%:37.5%, n=36) versus the poor responders (FokI+:FokI-, 41.7%:58.3%, n=30) after beta-blocker therapy (P=0.02). In a multiple regression analysis, the G(s)alpha genotype was the only independent predictor of BP response. These results suggest that the GNAS1 locus might carry a functional variant that influences BP variation and response to beta-blockade in essential hypertension.

    Hypertension (Dallas, Tex. : 1979) 1999;34;1;8-14

  • Stimulatory guanine nucleotide binding protein subunit 1 mutation in two siblings with pseudohypoparathyroidism type 1a and mother with pseudopseudohypoparathyroidism.

    Walden U, Weissörtel R, Corria Z, Yu D, Weinstein L, Kruse K and Dörr HG

    Division of Paediatric Endocrinology, University Hospital for Children and Adolescents, Erlangen, Germany.

    Unlabelled: Pseudohypoparathyroidism (PHP) type la is characterized by multihormone resistance and a constellation of somatic features referred to as Albright hereditary osteodystrophy. Several mutations in the gene coding for the Gs alpha subunit (GNAS1) have been described. Clinical symptoms are heterogeneous and initially laboratory parameters may be normal. We identified a 4 base pair deletion within GNAS1 in two affected siblings with PHP type la and their mother with presumed pseudo PHP. The female proband was diagnosed after an episode of apnoea and seizures. The younger brother was asymptomatic during infancy and had normal plasma parameters. PHP was diagnosed at the age of 4.4 years. Regular check-ups of siblings in families with index cases are therefore important. Molecular genetic analyses or biochemical screening for stimulatory guanine nucleotide binding protein defects should be performed.

    Conclusion: Different symptoms may be seen in patients with the same mutation causing pseudohypoparathyroidism or pseudopseudohypoparathyroidism. Therefore, clinical and biochemical investigations should be performed in all family members with an index patient.

    European journal of pediatrics 1999;158;3;200-3

  • GNAS1 mutational analysis in pseudohypoparathyroidism.

    Ahmed SF, Dixon PH, Bonthron DT, Stirling HF, Barr DG, Kelnar CJ and Thakker RV

    MRC Molecular Endocrinology Group, Imperial College School of Medicine, Hammersmith Hospital London, UK.

    Objective: Mutations of the GNAS1 gene, which is located on chromosome 20q13.11 and encodes the alpha-subunit of the stimulatory GTP-binding protein, have been identified in patients with pseudohypoparathyroidism type Ia (PHPIa) and pseudopseudohypoparathyroidism (PPHP). We have undertaken studies to determine the prevalence of GNAS1 mutations and to explore methods for their more rapid detection.

    Methods: Thirteen unrelated families (8 with PHPIa and PPHP patients, and 5 with PPHP patients only) were investigated for GNAS1 mutations in the 1050 base-pair (bp) region spanning exons 2-13 by single-stranded conformational polymorphism (SSCP) and DNA sequence analysis.

    Results: GNAS1 mutations were detected in 4 of the 8 families with PHPIa patients. These consisted of: two novel de novo missense mutations (Pro115Ser and Glu259Val) in two families and an identical 4 bp deletion of codons 189 and 190 resulting in a frame-shift in two unrelated families. These results expand the spectrum of GNAS1 mutations associated with this disorder and confirm the presence of a mutational hot-spot involving codons 189 and 190. SSCP analysis was found to be a specific and sensitive method that detected all 4 mutations. GNAS1 mutations were not detected in any of the PPHP only families.

    Conclusions: The pseudohypoparathyroid disorders appear to represent a heterogeneous group with GNAS1 mutations forming the molecular aetiology in approximately 50% of pseudohypoparathyroidism type Ia families. Such mutations can be reliably identified by single-stranded conformational polymorphism and this will help to supplement the clinical evaluation of some patients and their families, particularly as the disease may not be fully penetrant.

    Clinical endocrinology 1998;49;4;525-31

  • Concurrent hormone resistance (pseudohypoparathyroidism type Ia) and hormone independence (testotoxicosis) caused by a unique mutation in the G alpha s gene.

    Nakamoto JM, Zimmerman D, Jones EA, Loke KY, Siddiq K, Donlan MA, Brickman AS and Van Dop C

    Department of Pediatrics, University of California at Los Angeles 90095, USA.

    Defects in the G (guanine nucleotide-binding)-protein subunit (G alpha s) which stimulates adenylyl cyclase may result in either loss or gain of endocrine function. Reduced G alpha s activity is found in the hormone resistance syndrome, pseudohypoparathyroidism type Ia (PHP-Ia), while constitutive activation of G alpha s is associated with endocrine organ overactivity, including the gonadotropin-independent sexual precocity seen in patients with McCune-Albright syndrome. We identified two unrelated boys presenting with concurrent PHP-Ia and gonadotropin-independent sexual precocity (testotoxicosis). Mutational screening by denaturing gradient gel electrophoresis and sequencing of PCR-amplified exons of the G alpha s gene revealed a point mutation which generates an alanine-to-serine substitution in codon 366 of one G alpha s allele (A366S), an alanine present at the homologous position in all G-proteins. We have previously shown in transfected testis cells that the A366S mutation activates G alpha s by decreasing affinity for GDP, thereby increasing the rate of nucleotide exchange in a receptor-independent fashion. In contrast to differential stability of the activated mutant G alpha s protein in Leydig cells, with stability at 32 degrees C but not at 37 degrees C, skin fibroblasts with the mutation had the same reduced G alpha s levels at both temperatures. Our findings explain the limitation of clinical manifestations of G alpha s overactivity to testis, without involvement of other body appendages which are generally at lower than core body temperature. This unique mutation at a critically conserved residue of G alpha s is the first mutant G-protein which affects guanine nucleotide affinity and is associated with human disease, producing widely divergent and tissue-specific effects.

    Biochemical and molecular medicine 1996;58;1;18-24

  • Pseudohypoparathyroidism type Ia: two new heterozygous frameshift mutations in exons 5 and 10 of the Gs alpha gene.

    Shapira H, Mouallem M, Shapiro MS, Weisman Y and Farfel Z

    Biochemical Pharmacology Laboratory, Sheba Medical Center, Tel Hashome, Israel.

    Pseudohypoparathyroidism type Ia (PHP-Ia) is a hereditary disease characterized by resistance to PTH and other hormones that act via cAMP. Patients have deficient activity of Gs alpha, the alpha subunit of the G protein, which couples hormone receptors to stimulation of adenylate cyclase. We describe two new mutations discovered in two sporadic patients with PHP-Ia. Using genomic DNA, we have amplified exons 2-13 of the Gs alpha gene (GNAS1) by PCR, and sequenced the resulting products. Both patients had Albright's hereditary osteodystrophy, resistance to multiple hormones, and deficient Gs alpha activity. In the first patient, a deletion of a C in exon 5 at codon 115 was found. In the second patient, an insertion of a C in exon 10 at codon 267 was detected. Both these heterozygous mutations cause frameshift, and predict decreased production of Gs alpha. This report adds two new Gs alpha mutations to the known ten mutations recently described.

    Human genetics 1996;97;1;73-5

  • A heterozygous 4-bp deletion mutation in the Gs alpha gene (GNAS1) in a patient with Albright hereditary osteodystrophy.

    Weinstein LS, Gejman PV, de Mazancourt P, American N and Spiegel AM

    Molecular Pathophysiology Branch, National Institute of Diabetes, Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland 20892.

    Several heterozygous mutations within the gene encoding the alpha-subunit of Gs (GNAS1), the G protein that stimulates adenylyl cyclase, have been previously identified in patients with Albright hereditary osteodystrophy (AHO). We have now identified a fourth GNAS1 mutation from an AHO patient. Amplification by the polymerase chain reaction (PCR) of a genomic fragment encompassing GNAS1 exons 7 and 8 from one patient resulted in a product with aberrant migration on nondenaturing polyacrylamide and agarose gels. Direct DNA sequencing identified a 4-bp deletion in one allele of exon 7 encoding a frameshift with a premature stop codon. Analysis of lymphocyte RNA by reverse transcription-PCR and direct sequencing showed that the GNAS1 allele bearing the mutation is not expressed as mRNA. Consistent with this, Northern analysis revealed an approximate 50% deficiency in steady-state levels of GNAS1 mRNA. These findings further illustrate the heterogeneity of GNAS1 gene defects in AHO.

    Genomics 1992;13;4;1319-21

Literature (252)

Pubmed - human_disease

  • The T393C polymorphism in the gene GNAS1 of G protein is associated with survival of patients with invasive breast carcinoma.

    Otterbach F, Callies R, Frey UH, Schmitz KJ, Wreczycki C, Kimmig R, Siffert W and Schmid KW

    Institute of Pathology and Neuropathology, University Hospital of Essen, University of Duisburg-Essen, Hufelandstrasse 55, D-45122, Essen, Germany.

    The GNAS1 locus encodes the G(alpha)s protein which stimulates the formation of cyclic AMP (cAMP). Subsequently the cAMP pathway mediates various pleiotropic effects including regulation of apoptosis and proliferation. We have recently shown that genotypes of the single nucleotide polymorphism (SNP) T393C in the gene GNAS1 are associated with survival of patients suffering from bladder, renal cell and colorectal carcinoma. In the present study, the genotypes of the T393C SNP were determined in 279 patients with invasive breast carcinoma. Comparing the genotypes with the overall survival as well as important clinico-pathological parameters showed that carriers of the T allele had a significantly less favourable course of the disease when compared to carriers of the homozygous CC genotype. In multivariate analysis the homozygous TT genotype was independently associated with a decreased overall survival. Our results suggest that the GNAS1 T393C SNP is a novel genetic host factor for disease progression in patients with invasive breast carcinoma.

    Breast cancer research and treatment 2007;105;3;311-7

  • The CC genotype of the GNAS T393C polymorphism is associated with obesity and insulin resistance in women with polycystic ovary syndrome.

    Hahn S, Frey UH, Siffert W, Tan S, Mann K and Janssen OE

    Endokrinologikum Ruhr, Center for endocrine and metabolic diseases, Alter Markt 4, 44866 Bochum, Germany. susanne.hahn@endokrinologikum.com

    Objective: Variants in the Gs protein alpha subunit gene (GNAS1) are known to be involved in the pathogenesis of several endocrine and metabolic disorders. To understand genetic determinants of androgen excess, insulin resistance, and obesity in polycystic ovary syndrome (PCOS), we investigated the effect of the common GNAS1 T393C polymorphism on the phenotype of German PCOS women.

    Design: Two hundred and seventy-eight PCOS women and 820 Caucasian controls were genotyped for the common T393C polymorphism in GNAS1. To this end, genomic DNA was amplified by PCR with specific oligonucleotides and genotypes were determined using the restriction enzyme FokI. In addition, we evaluated whether the T393C polymorphism had an influence on the response to 6 months metformin treatment in a subgroup of 105 PCOS women.

    Methods: Anthropometric variables, metabolic parameters including indices of insulin resistance measured by oral glucose tolerance testing, and endocrine biochemical as well as clinical parameters were measured in all PCOS subjects.

    Results: GNAS1 genotype distributions were not significantly different between PCOS women and controls. In PCOS women, no significant differences in endocrine clinical and biochemical variables were found between the genotypes. However, the C-allele carrier group had significantly higher mean body weight, body mass index, leptin levels, and higher indices of insulin resistance compared with women with GNAS1 TT-genotype. Metformin treatment significantly improved hyperandrogenism, menstrual cyclicity, body weight, and insulin resistance independent of GNAS1 genotype. The major determinant of weight loss was body weight before treatment.

    Conclusion: The T393C polymorphism is not associated with PCOS in Caucasian women, but may represent a genetic marker for increased susceptibility for obesity in this cohort.

    European journal of endocrinology 2006;155;5;763-70

  • The GNAS1 T393C polymorphism predicts survival in patients with clear cell renal cell carcinoma.

    Frey UH, Lümmen G, Jäger T, Jöckel KH, Schmid KW, Rübben H, Müller N, Siffert W and Eisenhardt A

    Institut für Pharmakogenetik, Universitätsklinikum Essen, Germany. Ulrich.Frey@uni-essen.de

    Purpose: G proteins mediate signaling from cell surface receptors to specific intracellular proteins. In vitro cancer cell line studies revealed a link between the Galphas protein and proapoptotic processes. We have recently shown that TT genotypes of the GNAS1 T393C polymorphism display increased transcription of Galphas and a more favorable clinical course in bladder and colorectal cancer patients compared both with TC or CC genotypes.

    In the present study, 150 patients with clear cell renal cell carcinoma surgically treated by nephrectomy with curative intent were retrospectively genotyped to elucidate a potential association between T393C genotypes and clinical outcome.

    Results: The C-allele frequency in the renal cell carcinoma patient group was 0.51, which is not significantly different from that of a healthy blood donor group. Kaplan-Meier curves for tumor progression, development of metastasis, and tumor-related death showed a significant association of the T393C polymorphism with outcome (5-year cancer-specific survival rates: TT, 91%; TC, 81%; CC, 69%; P = 0.015). Multivariate Cox proportional analysis of a 10-year follow-up confirmed the T393C polymorphism as an independent prognostic factor in clear cell renal cell carcinoma. Homozygous CC patients were at highest risk for progression (hazard ratio, 2.48; P = 0.009) or tumor-related death (hazard ratio, 3.15; P = 0.018) compared with T-allele carriers.

    Conclusion: Our results show that besides tumor stage, lymph node status, and tumor grade, the GNAS1 T393C status is a novel independent host factor for disease progression in patients with clear cell renal cell carcinoma and provides further evidence for the T393C polymorphism as a general prognostic tumor marker.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2006;12;3 Pt 1;759-63

  • Effects of polymorphisms in beta1-adrenoceptor and alpha-subunit of G protein on heart rate and blood pressure during exercise test. The Finnish Cardiovascular Study.

    Nieminen T, Lehtimäki T, Laiho J, Rontu R, Niemelä K, Kööbi T, Lehtinen R, Viik J, Turjanmaa V and Kähönen M

    Dept. of Pharmacological Sciences, Medical School, Univ. of Tampere, Tampere FI-33014, Finland. tuomo.nieminen@iki.fi

    We tested whether the Arg389Gly and Ser49Gly polymorphisms of the beta1-adrenergic receptor gene ADRB1 and the T393C polymorphism of the G protein alpha-subunit gene GNAS1 modulate heart rate (HR) and blood pressure responses during an exercise stress test. The study population comprised 890 participants (563 men and 327 women, mean age 58.1 +/- 12.6 yr) of the Finnish Cardiovascular Study. Their HR, systolic (SAP), and diastolic arterial pressures (DAP) at rest, during exercise, and 4 min after the test were measured and analyzed by repeated-measurement ANOVA (RANOVA). Genotypes were detected by TaqMan 5' nuclease assay. In all subjects, and in men and women separately, the T393C of GNAS1 was the only polymorphism with genotype x time interaction in HR over the three study phases (P = 0.04, RANOVA). None of the polymorphisms presented genotype x time interaction in SAP or DAP responses (P > 0.10, RANOVA). In all subjects at rest, the Ser49Gly polymorphism of ADRB1 tended (P = 0.06, ANOVA) to differentiate HR. Arg389Gly polymorphism of ADRB1 affected maximal SAP during exercise (P = 0.04, ANOVA) and the change in SAP from rest to maximal (P = 0.03, ANOVA). Arg389 homozygotes, particularly men, were less likely to have ventricular extrasystoles during the exercise (odds ratio = 0.68, 95% confidence interval = 0.51-0.91, P = 0.009, and odds ratio = 0.60, 95% confidence interval = 0.42-0.86, P = 0.006, respectively) than did Gly389 carriers. In conclusion, polymorphisms examined appear to have modulatory effects on hemodynamics in a clinical exercise test setting. However, the effects in absolute numbers were minor and clinically possibly insignificant.

    Journal of applied physiology (Bethesda, Md. : 1985) 2006;100;2;507-11

  • GNAS1 T393C polymorphism and survival in patients with sporadic colorectal cancer.

    Frey UH, Alakus H, Wohlschlaeger J, Schmitz KJ, Winde G, van Calker HG, Jöckel KH, Siffert W and Schmid KW

    Institute of Pharmacology, University Hospital of Essen, Essen, Germany. Ulrich.Frey@uni-essen.de

    Purpose: Signaling via the G protein Galpha s pathway is linked to proapoptotic processes in cancer cell lines. We have recently shown an association between the GNAS1 T393C polymorphism and disease progression in patients with bladder cancer with homozygous TT genotypes displaying increased transcription of Galpha s and a more favorable clinical course compared with C-allele carriers.

    In the present study, 151 patients with sporadic colorectal cancer were retrospectively genotyped to examine a potential association between T393C genotypes and survival. Moreover, two other single-nucleotide polymorphisms in common haplotype blocks within the gene GNAS1 and their interaction with the T393C polymorphism were investigated.

    Results: The allele frequency in the patients group was not significantly different from that of healthy blood donors. Kaplan-Meier curves for overall survival (mean follow-up, 43 months) showed that in International Union Against Cancer (UICC) stages I to II, the 5-year survival rate was significantly higher in TT genotypes (87.8%) compared with TC (71.0%) and CC genotypes (50.0%; P = 0.009), whereas no genotype effect could be observed for UICC stages III to IV. In multivariate Cox proportional analysis the T393C polymorphism was an independent prognostic factor for survival. Homozygous CC patients were at highest risk for death (hazard ratio, 12.1; P = 0.006) compared with TT genotypes. Heterozygous patients had an intermediate risk compatible with a gene-dose effect. The two haplotype blocks investigated were not associated with clinical outcome.

    Conclusions: The results support the role of the T393C polymorphism as a marker for survival in patients with colorectal cancer stages I to II and in the identification of patients who may benefit from adjuvant chemotherapy.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2005;11;14;5071-7

  • Association between beta-adrenergic receptor polymorphisms and their G-protein-coupled receptors with body mass index and obesity in women: a report from the NHLBI-sponsored WISE study.

    Terra SG, McGorray SP, Wu R, McNamara DM, Cavallari LH, Walker JR, Wallace MR, Johnson BD, Bairey Merz CN, Sopko G, Pepine CJ and Johnson JA

    Department of Pharmacy Practice, University of Florida College of Pharmacy, Gainesville, FL 32610, USA.

    Objectives: The beta-adrenergic receptor (betaAR) genes are candidate genes for obesity because of their roles in energy homeostasis and promotion of lipolysis in human adipose tissue. Objective is to determine the association between obesity and polymorphisms in genes of the beta(1)AR (ADRB1), beta(2)AR (ADRB2), beta(3)AR (ADRB3), Gs protein alpha (GNAS1), to which all three beta-receptors couple and the G protein beta3 subunit (GNB3), to which beta(3)ARs couple.

    Design: A case-control genetic association study.

    Subjects: A total of 643 black or white women enrolled in Women's Ischemia Syndrome Evaluation (WISE) study.

    Measurements: Genotypes were determined by PCR with single primer extension. Associations between genotype and body mass index (BMI), waist-to-hip ratio (WHR), waist circumference, and obesity were made.

    Results: Polymorphisms in the three betaAR genes, GNAS1, and GNB3 were not associated with BMI, WHR, waist circumference, or obesity. Linear and logistic regression analyses found no contribution of either genotype or haplotype with anthropometric measurements or obesity.

    Conclusions: Our study suggests that among American women with suspected coronary heart disease, polymorphisms in the betaARs and their G-protein-coupled receptors do not contribute to increased BMI, WHR, waist circumference, or obesity. Given that 50% of all women die from coronary heart disease, and a higher percentage have heart disease during their lifetime, our results are likely generalizable to many American women.

    Funded by: NCRR NIH HHS: M01-RR00425; NHLBI NIH HHS: N01-HV68161, N01-HV68162, N01-HV68163, N01-HV68164, R03HL65729, U01-HL64924-01

    International journal of obesity (2005) 2005;29;7;746-54

  • The T393C polymorphism of the G alpha s gene (GNAS1) is a novel prognostic marker in bladder cancer.

    Frey UH, Eisenhardt A, Lümmen G, Rübben H, Jöckel KH, Schmid KW and Siffert W

    Institut für Pharmakologie, Universitätsklinikum, Essen, Hufelandstrasse 55, D-45122 Essen, Germany. Ulrich.Frey@uni-essen.de

    The G protein G(alpha)s pathway is linked to proapoptotic signaling in cancer cell lines. To assess the role of the GNAS1 locus encoding G(alpha)s as a genetic factor for disease progression of transitional cell carcinoma (TCC) of the bladder, we genotyped the synonymous T393C polymorphism in 254 patients with TCC (minor allele frequency: 0.43) to examine a potential association between genotypes and disease progression. Using Kaplan-Meier estimates to calculate 5-year probabilities of follow-up, we could show that progression-free survival, metastasis-free survival, and cancer-specific survival was significantly increased in TT genotypes (56%, 84%, 82%) compared with CC genotypes (35%, 53%, 58%). In multivariate Cox proportional hazard analysis, the T393C polymorphism was an independent prognostic factor for clinical outcome. Homozygous CC patients were at highest risk for progression [odds ratio (OR), 1.94; P = 0.020], metastasis (OR, 3.49; P = 0.005), and tumor-related death (OR, 2.49; P = 0.031) compared with TT genotypes. Heterozygous patients had an intermediate risk compatible with a gene-dose effect. Real-time PCR analysis of urothelial tumor tissue as well as adipose and heart tissue revealed that G(alpha)s mRNA expression was highest in TT genotypes, indicating a proapoptotic effect in these genotypes. In conclusion, the GNAS1 T393C status associated with differential G(alpha)s mRNA expression is a novel independent prognostic marker for clinical outcome supporting a functional role of G(alpha)s in bladder cancer progression.

    Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2005;14;4;871-7

  • Albright's hereditary osteodystrophy (pseudohypoparathyroidism type Ia): clinical case with a novel mutation of GNAS1.

    Garavelli L, Pedori S, Zanacca C, Caselli G, Loiodice A, Mantovani G, Ammenti A, Virdis R and Banchini G

    Department of Pediatrics, S. Maria Nuova Hospital, Reggio Emilia, Italy. garavelli.livia@asmn.re.it

    Albright's hereditary osteodystrophy is characterized by ectopic calcification and ossification, round face, short hands and feet with short terminal phalanges, short metacarpals (especially 4th and 5th) and absence of the 4th knuckle (brachydactyly type E). Here we describe a case that recently came to our attention of a girl suffering from seizures caused by hypocalcaemia, in which the clinical diagnosis of Albright's hereditary osteodystrophy and Pseudohypoparathyroidism (PHP) (Pseudohypoparathyroidism Ia) was confirmed by DNA molecular analysis. This analysis revealed a novel mutation of GNAS 1, resulting in the nonsense mutation of exon 13 (CAG-->TAG, codon 384). This result expands the spectrum of GNAS1 mutations associated with this disorder.

    Acta bio-medica : Atenei Parmensis 2005;76;1;45-8

  • Association of a GNAS1 gene variant with hypertension and diabetes mellitus.

    Yamamoto M, Abe M, Jin JJ, Wu Z, Tabara Y, Mogi M, Kohara K, Miki T and Nakura J

    Department of Geriatric Medicine, School of Medicine, Ehime University, Onsen-gun, Ehime, Japan.

    Previous studies have shown that the T allele of the GNAS1 T393C polymorphism is associated with poor responsiveness to beta-blockade and that the T393C polymorphism interacts with cigarette smoking and alcohol consumption in the pathogenesis of hypertension. Thus, the T393C polymorphism is likely to interact with beta-adrenoceptor (beta-AR) stimulation in the pathogenesis of hypertension. Although this interaction might be caused by a direct effect of Gs proteins on the cardiovascular system, it could also result from an indirect effect of Gs proteins mediated by glucose metabolism. Moreover, association studies are often irreproducible. We therefore examined the possible interaction between the T393C polymorphism and gamma-glutamyl transpeptidase (GGT), which is an established biomarker of alcohol consumption, in the association with glucose metabolism as well as with hypertension in a Japanese population. Genotyping for GNAS1 was performed by using the polymerase chain reaction-restriction fragment length polymorphism method in all 821 samples. The present study showed a significant interaction between the T393C polymorphism and GGT in the association with hypertension (p =0.033). This interaction was even more significant after adjustment for all confounding factors (p =0.0025). In contrast, analysis of the possible interaction of the T393C polymorphism with GGT in the association with diabetes mellitus or fasting plasma glucose failed to show a significant result. These results did not support the hypothesis that the interaction between the T393C polymorphism and GGT in the association with hypertension could be caused by an indirect effect of Gs proteins mediated by glucose metabolism.

    Hypertension research : official journal of the Japanese Society of Hypertension 2004;27;12;919-24

  • G protein polymorphisms do not predict weight loss and improvement of hypertension in severely obese patients.

    Potoczna N, Wertli M, Steffen R, Ricklin T, Lentes KU and Horber FF

    Klinik Hirslanden, Zürich, Switzerland.

    Both the gene encoding the alpha subunit of G stimulatory proteins (GNAS1) and the beta3 subunit gene (GNB3) of G proteins are associated with obesity and/or hypertension. Moreover, the TT/TC825 polymorphism of GNB3 predicts greater weight loss than the CC825 polymorphism in obese patients (mean body mass index, 35 kg/m2) undergoing a structured nonpharmacologic weight loss program. Gastric banding enforces a low-calorie diet by diminishing the need for volitional adherence. It is unknown whether these polymorphisms predict the variable weight loss in patients after bariatric surgery. Three hundred and four severely obese patients (mean +/- SEM age, 42 +/- 1 years; 245 women and 59 men; mean +/- SEM body mass index, 43.9 +/- 0.3 kg/m2) followed prospectively for at least 3 years after surgery were genotyped for the GNB3 C825T, G814A, and GNAS1 T393 polymorphisms. All analyses were performed blinded to the phenotypic characteristics of the study group. Frequencies of polymorphisms were comparable to those previously published. No polymorphism studied predicted 3-year weight loss or was associated with high blood pressure in severely obese patients after gastric banding. Multivariate analysis of potentially confounding factors such as reoperation rate or use of sibutramine or orlistat revealed similar results (P > 0.1). Regardless of the mechanism(s) involved for these discordant findings, GNB3 C825T, G814A, and GNAS1 T393C polymorphisms do not seem to be reliable predictors of long-term weight loss.

    Journal of gastrointestinal surgery : official journal of the Society for Surgery of the Alimentary Tract 2004;8;7;862-8; discussion 868

  • Activating GNAS1 gene mutations in patients with premature thelarche.

    Román R, Johnson MC, Codner E, Boric MA, áVila A and Cassorla F

    Institute of Maternal and Child Research, San Borja Arriarán Clinical Hospital, School of Medicine, University of Chile, Santiago, Chile.

    Objective: To identify GNAS1 gene mutations in girls with exaggerated and/or chronic fluctuating thelarche for at least 1-year duration with no other signs of precocious puberty, skeletal dysplasia, or typical skin lesions of McCune-Albright syndrome.

    We studied the GNAS1 gene mutation by allele-specific polymerase chain reaction and enzymatic digestion in leukocyte DNA in 23 girls previously described.

    Results: Fluctuating thelarche was present in 14 girls and exaggerated thelarche was observed in 9. Molecular study revealed that 6 girls had a substitution of arginine by histidine in codon 201 (R201H [+]). Three R201H (+) girls reached their menarche at a mean chronologic age of 10.8 years and 9 of the R201H (-) girls at a mean age of 11 years.

    Conclusions: Activating mutations of GNAS1 gene may be observed in some girls with chronic fluctuating and/or exaggerated thelarche, without other classic signs of McCune-Albright syndrome.

    The Journal of pediatrics 2004;145;2;218-22

  • Progressive osseous heteroplasia resulting from a new mutation in the GNAS1 gene.

    Chan I, Hamada T, Hardman C, McGrath JA and Child FJ

    Department of Dermatology, St Mary's Hospital, London, UK. ien.chan@kcl.ac.uk

    Progressive osseous heteroplasia (OMIM 166350) is a rare autosomal dominant condition that presents in childhood as dermal ossification and may progress deeper to involve subcutaneous fat and connective tissue. Recently, paternally inherited inactivating mutations in the GNAS1 gene on chromosome 20q13 have been implicated in the pathogenesis, although sporadic cases have also been reported. We report a 9-year-old British Chinese girl with progressive osseous heteroplasia resulting from a de novo missense mutation (W281R) in the GNAS1 gene. She is of small stature (0.4th centile) and started to develop skin lesions at the age of 9 months. These have been confirmed histologically as osteoma cutis. She is of normal intelligence and development and has no dysmorphic features. The GNAS1 gene exhibits imprinting and maternally inherited mutations have previously been shown to result in Albright's hereditary osteodystrophy (OMIM 103580) with pseudohypothyroidism type 1a, whereas paternally inherited mutations result in progressive osseous heteroplasia or the Albright's hereditary osteodystrophy phenotype with pseudopseudohypothyroidism (OMIM 300800). With only nine mutations of the GNAS1 gene reported so far in progressive osseous heteroplasia, this new mutation helps to extend further the genotype-phenotype correlation.

    Clinical and experimental dermatology 2004;29;1;77-80

  • Cushing's syndrome secondary to adrenocorticotropin-independent macronodular adrenocortical hyperplasia due to activating mutations of GNAS1 gene.

    Fragoso MC, Domenice S, Latronico AC, Martin RM, Pereira MA, Zerbini MC, Lucon AM and Mendonca BB

    Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM-42, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil 01060-970. mariofragoso@uol.com.br

    ACTH-independent macronodular adrenal hyperplasia (AIMAH) is an uncommon cause of Cushing's syndrome characterized by bilateral nodular adrenocortical hyperfunction in the presence of suppressed ACTH levels. We investigated whether activating mutations in the ACTH receptor (MC2-R) or G(s alpha) (GNAS1) genes might be involved in AIMAH genesis. Five women with Cushing's syndrome due to AIMAH, confirmed by histological studies, and no signs of McCune-Albright syndrome were selected for molecular analysis of these genes. The single exon of the MC2-R gene and exons 8 and 9 of the GNAS1 gene were amplified by PCR in genomic DNA from adrenal nodules and peripheral blood. Direct sequencing revealed only MC2-R wild-type sequences. GNAS1 PCR products at denaturing gradient gel electrophoresis revealed abnormal migration patterns in adrenal tissues of three patients. Automatic sequencing showed two different activating mutations at codon Arg(201) of GNAS1, a substitution by histidine in two cases and by serine in one case. In conclusion, we found two different gsp mutations in three patients with Cushing's syndrome due to AIMAH, and we speculate whether they belong to the spectrum of McCune-Albright syndrome or whether these are the first reported cases of AIMAH due to gsp mutations.

    The Journal of clinical endocrinology and metabolism 2003;88;5;2147-51

  • Pubertal development in patients with McCune-Albright syndrome or pseudohypoparathyroidism.

    de Sanctis C, Lala R, Matarazzo P, Andreo M and de Sanctis L

    Department of Pediatric Endocrinology, Regina Margherita Children 's Hospital, Turin, Italy. malattierare@libero.it

    Gain or loss of function mutations of the GNAS1 gene lead to McCune-Albright syndrome (MAS) or pseudohypoparathyroidism Ia (PHP-Ia), respectively. Patients with MAS, caused by a post-zygotic missense mutation leading to constitutive activation of Gs alpha, suffer from gonadotropin-independent precocious puberty, and delayed or incomplete sexual development and reproductive dysfunction is found in women with PHP-Ia, an inherited disorder caused by deficient expression or function of the Gs alpha protein. In females with MAS, 50% developed precocious puberty by the age of 4 years, the remaining between 4 and 8 years. Peripheral precocious puberty is often atypical and characterized by alternate periods of rapid progression and regression of pubertal development; menstrual bleeding may occur before breast development. Ovarian cyst growth and regression is often described as a sign of ovarian follicle hyperactivation. Notwithstanding this clinical heterogeneity, a subset of patients with MAS develop relentlessly progressive precocious puberty ultimately resulting in premature epiphyseal fusion and reduced adult stature. Long-term information on reproductive function has been obtained in females: some patients had regular menses without ovarian cysts on pelvic US scan, whereas others were oligomenorrheic and showed recurrent ovarian cysts. In males with MAS, precocious puberty occurred in three patients between 4 and 9 years of age. In one patient, long-term follow-up demonstrated normal plasma testosterone and gonadotropin values at the age of 17 years. On testicular sonography, multiple hyperechogeneic spots were found in both testicles (snow-storm appearance). Female patients with PHP-Ia were oligomenorrheic or amenorrheic; more than half had delayed or incomplete sexual development, They were mildly hypoestrogenic with normal to slightly elevated serum gonadotropin levels. These clinical and biochemical findings indicate partial resistance of the theca and granulosa cells of the ovary to gonadotropins due to deficient Gs alpha activity. Responsiveness might be sufficient to promote some degree of follicular development and steroid secretion, but insufficient to induce ovulation

    Journal of pediatric endocrinology & metabolism : JPEM 2003;16 Suppl 2;293-6

  • Constitutional deletion of chromosome 20q in two patients affected with albright hereditary osteodystrophy.

    Aldred MA, Aftimos S, Hall C, Waters KS, Thakker RV, Trembath RC and Brueton L

    Division of Medical Genetics, University of Leicester, and Department of Molecular Genetics, University Hospitals of Leicester NHS Trust, Leicester, UK. maldred@hgmp.mrc.ac.uk

    Albright hereditary osteodystrophy (AHO) results from heterozygous inactivation of G(s)alpha, encoded by the GNAS1 locus on the distal long arm of chromosome 20. This autosomal dominant condition is characterized by short stature, obesity, shortening of the metacarpals and metatarsals, and variable mental retardation and may also include end-organ resistance to multiple hormones. Small insertions and deletions or point mutations of GNAS1 are found in approximately 80% of patients with AHO. The remainder may be accounted for by larger genomic rearrangements, but none have been reported to date. We now describe two patients with constitutional 20q deletions and features of AHO. Such deletions are rare in the published literature and have not previously been associated with AHO. Molecular genetic analysis confirmed complete deletion of GNAS1 in both patients. Parental origin could be determined in both cases and provides further support for the parent-of-origin effect on the biochemical status of patients with AHO.

    American journal of medical genetics 2002;113;2;167-72

  • Familial ACTH-independent Cushing's syndrome with bilateral macronodular adrenal hyperplasia clinically affecting only female family members.

    Nies C, Bartsch DK, Ehlenz K, Wild A, Langer P, Fleischhacker S and Rothmund M

    Department of General Surgery, Klinik für Visceral-, Thorax- und Gefässchirurgue, Philipps-University Marburg, Germany. nies@mailer.uni-marburg.de

    Primary adrenal hyperplasia, which may occur as a familial disorder, is a rare cause of ACTH-independent Cushing's syndrome. In most of these cases the underlying pathology is primary adrenocortical micronodular dysplasia. Very few cases of familial Cushing's syndrome due to primary macronodular adrenal hyperplasia have been described. We report a family with seven affected family members. The pedigree indicates an autosomal dominantly inherited disorder. Interestingly only female family members developed the clinically apparent syndrome. The only available obligatory male gene carrier failed to adequately suppress his plasma cortisol level on overnight dexamethasone suppression test. His adrenal glands showed nodular enlargement on abdominal computed tomographic imaging. Screening of the MEN 1 gene and genetic analysis of the hot spot regions of the GNAS 1 (codons 201 and 227) and GNAI 2 (codons 179 and 205) genes did not show any mutations in the constitutional DNA or the adrenal tissue DNA of the index patient. In conclusion, this family is the largest kindred reported in the literature with ACTH-independent Cushing's syndrome due to autosomal dominant inherited macronodular adrenocortical hyperplasia. Four currently alive and affected family members in two generations and further careful observation of the yet unaffected members of the third available generation might offer the opportunity to identify the still unknown gene defect in the future.

    Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association 2002;110;6;277-83

  • GNAS1 lesions in pseudohypoparathyroidism Ia and Ic: genotype phenotype relationship and evidence of the maternal transmission of the hormonal resistance.

    Linglart A, Carel JC, Garabédian M, Lé T, Mallet E and Kottler ML

    Department of Pediatric Endocrinology, Groupe Hospitalier Cochin-Saint Vincent de Paul, Assisvance Publique-Hôpitaux de Paris, 75014 Paris, France.

    We conducted clinical and biological studies including screening for mutations in the gene encoding the alpha subunit of G(s) (GNAS1) in 30 subjects (21 unrelated families) with Albright's hereditary osteodystrophy (AHO), pseudohypoparathyroidism (PHP); and decreased erythrocyte G(s) activity (PHP-Ia; n = 19); AHO and decreased erythrocyte G(s) activity (isolated AHO; n = 10); or AHO, hormonal resistance, and normal erythrocyte G(s) activity (PHP-Ic; n = 1). A heterozygous GNAS1 gene lesion was found in 14 of 17 PHP-Ia index cases (82%), including 11 new mutations and a mutational hot-spot involving codons 189-190 (21%). These lesions lead to a truncated protein in all but three cases with missense mutations R280K, V159M, and D156N. In the patient diagnosed with PHP-Ic, G(s)alpha protein was shortened by just four amino acids, a finding consistent with the conservation of G(s) activity in erythrocytes and the loss of receptor contact. No GNAS1 lesions were found in individuals with isolated AHO that were not relatives to PHP-Ia patients (n = 5). Intrafamilial segregation analyses of the mutated GNAS1 allele in nine PHP-Ia patients established that the mutation had either occurred de novo on the maternal allele (n = 4) or had been transmitted by a mother with a mild phenotype (n = 5). This finding is consistent with an imprinting of GNAS1 playing a role in the clinical phenotype of loss of function mutations and with a functional maternal GNAS1 allele having a predominant role in preventing the hormonal resistance of PHP-Ia.

    The Journal of clinical endocrinology and metabolism 2002;87;1;189-97

  • [Albright hereditary osteodystrophy: identification of a novel mutation in a family].

    Bastida Eizaguirre M, Iturbe Ortiz De Urbina R, Arto Urzainqui M, Ezquerra Larreina R and Escalada San Martín J

    Servicios de Pediatría Endocrinología. Hospital Santiago Apóstol. Vitoria. mbastida@hsan.osakidetza.net

    Studies to detect mutations in the GNAS1 gene were performed in a male patient with features of Albright hereditary osteodystrophy and resistance of target tissues to parathyroid hormone (Pseudohypoparathyroidism Ia). The same investigations were carried out in the patient's mother who showed somatic features of Albright's hereditary osteodystrophy and brachymetacarpia without resistance to parathyroid hormone (Pseudopseudohypoparathyroidism). A point mutation designated c.794GA (R265H) in exon 10 of GNAS1 was identified in DNA from the patient and his mother. This novel mutation in exon 10 of GNA

    Anales espanoles de pediatria 2001;54;6;598-600

  • Study of the multiple endocrine neoplasia type 1, growth hormone-releasing hormone receptor, Gs alpha, and Gi2 alpha genes in isolated familial acromegaly.

    Jorge BH, Agarwal SK, Lando VS, Salvatori R, Barbero RR, Abelin N, Levine MA, Marx SJ and Toledo SP

    Endocrine Genetics Unit (LIM-25) and Hormone and Molecular Genetics Laboratory, Endocrinology Section, Department of Medicine, University of Sao Paulo School of Medicine, Sao Paulo SP 01246-903, Brazil. beatrizjorge@hotmail.com

    Familial acromegaly may occur as an isolated pituitary disorder or as a feature of hereditary syndromes, such as multiple endocrine neoplasia type 1 (MEN1) or the Carney complex. Herein, we characterized a newly identified kindred with isolated acromegaly and searched for germline mutation in genes that have been associated with endocrine tumors [i.e. MEN1, Gs alpha (GNAS1), and Gi2 alpha (GNAI2)], as well as the GHRH receptor (GHRH-R) gene. Genomic DNA was used to amplify exons 2-10 of MEN1, followed by dideoxy fingerprinting mutation analysis and direct sequencing. The GHRH-R gene was analyzed via direct sequencing of PCR-amplified fragments representing the coding exons and intron-exon junctions. To exclude mutation at hot spot areas of GNAS1 and GNAI2, exons 8 and 9 of GNAS1 and exons 5 and 6 of GNAI2 were amplified and screened for mutation via denaturing gradient gel electrophoresis. No mutations were detected in any of the four genes. The present data extend prior reports of the absence of mutation in MEN1, GHRH-R, and GNAS1 and describe the first family with isolated acromegaly in which germline mutation in GNAI2 has been searched.

    Funded by: NCRR NIH HHS: 3-M01-RR-000052

    The Journal of clinical endocrinology and metabolism 2001;86;2;542-4

  • Selective resistance to parathyroid hormone caused by a novel uncoupling mutation in the carboxyl terminus of G alpha(s). A cause of pseudohypoparathyroidism type Ib.

    Wu WI, Schwindinger WF, Aparicio LF and Levine MA

    Division of Pediatric Endocrinology, Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.

    G(s) is a heterotrimeric (alpha, beta, and gamma chains) G protein that couples heptahelical plasma membrane receptors to stimulation of adenylyl cyclase. Inactivation of one GNAS1 gene allele encoding the alpha chain of G(s) (G alpha(s)) causes pseudohypoparathyroidism type Ia. Affected subjects have resistance to parathyroid hormone (PTH) and other hormones that activate adenylyl cyclase plus somatic features termed Albright hereditary osteodystrophy. By contrast, subjects with pseudohypoparathyroidism type Ib have hormone resistance that is limited to PTH and lack Albright hereditary osteodystrophy. The molecular basis for pseudohypoparathyroidism type Ib is unknown. We analyzed the GNAS1 gene for mutations using polymerase chain reaction to amplify genomic DNA from three brothers with pseudohypoparathyroidism type Ib. We identified a novel heterozygous 3-base pair deletion causing loss of isoleucine 382 in the three affected boys and their clinically unaffected mother and maternal grandfather. This mutation was absent in other family members and 15 additional unrelated subjects with pseudohypoparathyroidism type Ib. To characterize the signaling properties of the mutant G alpha(s), we used site-directed mutagenesis to introduce the isoleucine 382 deletion into a wild type G alpha(s) cDNA, transfected HEK293 cells with either wild type or mutant G alpha(s) cDNA, plus cDNAs encoding heptahelical receptors for PTH, thyrotropic hormone, or luteinizing hormone, and we measured cAMP production in response to hormone stimulation. The mutant G alpha(s) protein was unable to interact with the receptor for PTH but showed normal coupling to the other coexpressed heptahelical receptors. These results provide evidence of selective uncoupling of the mutant G alpha(s) from PTH receptors and explain PTH-specific hormone resistance in these three brothers with pseudohypoparathyroidism type Ib. The absence of PTH resistance in the mother and maternal grandfather who carry the same mutation is consistent with current models of paternal imprinting of the GNAS1 gene.

    Funded by: NCRR NIH HHS: RR0035; NIDDK NIH HHS: DK34281

    The Journal of biological chemistry 2001;276;1;165-71

  • Deficiency of the alpha-subunit of the stimulatory G protein and severe extraskeletal ossification.

    Eddy MC, Jan De Beur SM, Yandow SM, McAlister WH, Shore EM, Kaplan FS, Whyte MP and Levine MA

    Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, Missouri 63131, USA.

    Progressive osseous heteroplasia (POH) is a rare disorder characterized by dermal ossification beginning in infancy followed by increasing and extensive bone formation in deep muscle and fascia. We describe two unrelated girls with typical clinical, radiographic, and histological features of POH who also have findings of another uncommon heritable disorder, Albright hereditary osteodystrophy (AHO). One patient has mild brachydactyly but no endocrinopathy, whereas the other manifests brachydactyly, obesity, and target tissue resistance to thyrotropin and parathyroid hormone (PTH). Levels of the alpha-subunit of the G protein (Gsalpha) were reduced in erythrocyte membranes from both girls and a nonsense mutation (Q12X) in exon 1 of the GNAS1 gene was identified in genomic DNA from the mildly affected patient. Features of POH and AHO in two individuals suggest that these conditions share a similar molecular basis and pathogenesis and that isolated severe extraskeletal ossification may be another manifestation of Gsalpha deficiency.

    Funded by: NIAMS NIH HHS: 2R01-AR41916-04; NIDDK NIH HHS: DK 34281; PHS HHS: GCRC 00055

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2000;15;11;2074-83

  • GNAS1 mutation and Cbfa1 misexpression in a child with severe congenital platelike osteoma cutis.

    Yeh GL, Mathur S, Wivel A, Li M, Gannon FH, Ulied A, Audi L, Olmstead EA, Kaplan FS and Shore EM

    Department of Orthopaedic Surgery, University of Pennsylvania, School of Medicine, Philadelphia 19104-6081, USA.

    We evaluated a 7-year-old girl with severe platelike osteoma cutis (POC), a variant of progressive osseous heteroplasia (POH). The child had congenital heterotopic ossification of dermis and subcutaneous fat that progressed to involve deep skeletal muscles of the face, scalp, and eyes. Although involvement of skeletal muscle is a prominent feature of POH, heterotopic ossification has not been observed in the head, face, or extraocular muscles. The cutaneous ossification in this patient was suggestive of Albright hereditary osteodystrophy (AHO); however, none of the other characteristic features of AHO were expressed. Inactivating mutations of the GNAS1 gene, which encodes the alpha-subunit of the stimulatory G protein of adenylyl cyclase, is the cause of AHO. Mutational analysis of GNAS1 using genomic DNA of peripheral blood and of lesional and nonlesional tissue from our patient revealed a heterozygous 4-base pair (bp) deletion in exon 7, identical to mutations that have been found in some AHO patients. This 4-bp deletion in GNAS1 predicts a protein reading frameshift leading to 13 incorrect amino acids followed by a premature stop codon. To investigate pathways of osteogenesis by which GNAS1 may mediate its effects, we examined the expression of the obligate osteogenic transcription factor Cbfa1/RUNX2 in lesional and uninvolved dermal fibroblasts from our patient and discovered expression of bone-specific Cbfa1 messenger RNA (mRNA) in both cell types. These findings document severe heterotopic ossification in the absence of AHO features caused by an inactivating GNAS1 mutation and establish the GNAS1 gene as the leading candidate gene for POH.

    Funded by: NIAMS NIH HHS: 1-RO1-AR46831-01, 2-RO1-AR41916-04, R01 AR041916

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2000;15;11;2063-73

  • Mutations of the GNAS1 gene, stromal cell dysfunction, and osteomalacic changes in non-McCune-Albright fibrous dysplasia of bone.

    Bianco P, Riminucci M, Majolagbe A, Kuznetsov SA, Collins MT, Mankani MH, Corsi A, Bone HG, Wientroub S, Spiegel AM, Fisher LW and Robey PG

    Dipartimento di Medicina Sperimentale, Università dell'Aquila, Italy.

    Activating missense mutations of the GNAS1 gene, encoding the alpha subunit of the stimulatory G protein (Gs), have been identified in patients with the McCune-Albright syndrome (MAS; characterized by polyostotic fibrous dysplasia, café au lait skin pigmentation, and endocrine disorders). Because fibrous dysplasia (FD) of bone also commonly occurs outside of the context of typical MAS, we asked whether the same mutations could be identified routinely in non-MAS FD lesions. We analyzed a series of 8 randomly obtained, consecutive cases of non-MAS FD and identified R201 mutations in the GNAS1 gene in all of them by sequencing cDNA generated by amplification of genomic DNA using a standard primer set and by using a novel, highly sensitive method that uses a protein nucleic acid (PNA) primer to block amplification of the normal allele. Histologic findings were not distinguishable from those observed in MAS-related FD and included subtle changes in cell shape and collagen texture putatively ascribed to excess endogenous cyclic adenosine monophosphate (cAMP). Osteomalacic changes (unmineralized osteoid) were prominent in lesional FD bone. In an in vivo transplantation assay, stromal cells isolated from FD failed to recapitulate a normal ossicle; instead, they generated a miniature replica of fibrous dysplasia. These data provide evidence that occurrence of GNAS1 mutations, previously noted in individual cases of FD, is a common and perhaps constant finding in non-MAS FD. These findings support the view that FD, MAS, and nonskeletal isolated endocrine lesions associated with GNAS1 mutations represent a spectrum of phenotypic expressions (likely reflecting different patterns of somatic mosaicism) of the same basic disorder. We conclude that mechanisms underlying the development of the FD lesions, and hopefully mechanism-targeted therapeutic approaches to be developed, must also be the same in MAS and non-MAS FD.

    Funded by: Telethon: E.1029

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2000;15;1;120-8

  • Association of the G(s)alpha gene with essential hypertension and response to beta-blockade.

    Jia H, Hingorani AD, Sharma P, Hopper R, Dickerson C, Trutwein D, Lloyd DD and Brown MJ

    Clinical Pharmacology Unit, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK. h.jiia@ucl.ac.uk

    We examined whether the GNAS1 locus, encoding the G(s) protein alpha-subunit (G(s)alpha), is implicated in the genetic causes of essential hypertension. A common silent polymorphism (ATT-->ATC, Ile(131)) was identified in exon 5 of the G(s)alpha gene by single-strand conformation polymorphism analysis and DNA sequencing. This polymorphism consists of the presence (+) or absence (-) of a restriction site for FokI. Only 1 other rare allele was found in the coding region; the high GC content of the 5' noncoding sequence prevented mutation scanning of the promoter region of the gene. There was a significant difference in frequency of the FokI alleles between 268 white hypertensives (FokI+:FokI-, 51%:49%) and a matched group of 231 control subjects (FokI+:FokI-, 58%:42%) (P=0.02). Multiple regression analysis showed that the FokI genotype was independently related to the level of untreated systolic blood pressure in 294 well-characterized white hypertensives (P=0.01) but not in normotensives. The influence of the FokI allele on blood pressure (BP) response to beta-blockade was examined in 114 of the patients randomly assigned to this class of drug. Significant differences in frequency of the FokI allele were observed in the good responders (FokI+:FokI-, 62.5%:37.5%, n=36) versus the poor responders (FokI+:FokI-, 41.7%:58.3%, n=30) after beta-blocker therapy (P=0.02). In a multiple regression analysis, the G(s)alpha genotype was the only independent predictor of BP response. These results suggest that the GNAS1 locus might carry a functional variant that influences BP variation and response to beta-blockade in essential hypertension.

    Hypertension (Dallas, Tex. : 1979) 1999;34;1;8-14

  • Stimulatory guanine nucleotide binding protein subunit 1 mutation in two siblings with pseudohypoparathyroidism type 1a and mother with pseudopseudohypoparathyroidism.

    Walden U, Weissörtel R, Corria Z, Yu D, Weinstein L, Kruse K and Dörr HG

    Division of Paediatric Endocrinology, University Hospital for Children and Adolescents, Erlangen, Germany.

    Unlabelled: Pseudohypoparathyroidism (PHP) type la is characterized by multihormone resistance and a constellation of somatic features referred to as Albright hereditary osteodystrophy. Several mutations in the gene coding for the Gs alpha subunit (GNAS1) have been described. Clinical symptoms are heterogeneous and initially laboratory parameters may be normal. We identified a 4 base pair deletion within GNAS1 in two affected siblings with PHP type la and their mother with presumed pseudo PHP. The female proband was diagnosed after an episode of apnoea and seizures. The younger brother was asymptomatic during infancy and had normal plasma parameters. PHP was diagnosed at the age of 4.4 years. Regular check-ups of siblings in families with index cases are therefore important. Molecular genetic analyses or biochemical screening for stimulatory guanine nucleotide binding protein defects should be performed.

    Conclusion: Different symptoms may be seen in patients with the same mutation causing pseudohypoparathyroidism or pseudopseudohypoparathyroidism. Therefore, clinical and biochemical investigations should be performed in all family members with an index patient.

    European journal of pediatrics 1999;158;3;200-3

  • Concurrent hormone resistance (pseudohypoparathyroidism type Ia) and hormone independence (testotoxicosis) caused by a unique mutation in the G alpha s gene.

    Nakamoto JM, Zimmerman D, Jones EA, Loke KY, Siddiq K, Donlan MA, Brickman AS and Van Dop C

    Department of Pediatrics, University of California at Los Angeles 90095, USA.

    Defects in the G (guanine nucleotide-binding)-protein subunit (G alpha s) which stimulates adenylyl cyclase may result in either loss or gain of endocrine function. Reduced G alpha s activity is found in the hormone resistance syndrome, pseudohypoparathyroidism type Ia (PHP-Ia), while constitutive activation of G alpha s is associated with endocrine organ overactivity, including the gonadotropin-independent sexual precocity seen in patients with McCune-Albright syndrome. We identified two unrelated boys presenting with concurrent PHP-Ia and gonadotropin-independent sexual precocity (testotoxicosis). Mutational screening by denaturing gradient gel electrophoresis and sequencing of PCR-amplified exons of the G alpha s gene revealed a point mutation which generates an alanine-to-serine substitution in codon 366 of one G alpha s allele (A366S), an alanine present at the homologous position in all G-proteins. We have previously shown in transfected testis cells that the A366S mutation activates G alpha s by decreasing affinity for GDP, thereby increasing the rate of nucleotide exchange in a receptor-independent fashion. In contrast to differential stability of the activated mutant G alpha s protein in Leydig cells, with stability at 32 degrees C but not at 37 degrees C, skin fibroblasts with the mutation had the same reduced G alpha s levels at both temperatures. Our findings explain the limitation of clinical manifestations of G alpha s overactivity to testis, without involvement of other body appendages which are generally at lower than core body temperature. This unique mutation at a critically conserved residue of G alpha s is the first mutant G-protein which affects guanine nucleotide affinity and is associated with human disease, producing widely divergent and tissue-specific effects.

    Biochemical and molecular medicine 1996;58;1;18-24

  • Pseudohypoparathyroidism type Ia: two new heterozygous frameshift mutations in exons 5 and 10 of the Gs alpha gene.

    Shapira H, Mouallem M, Shapiro MS, Weisman Y and Farfel Z

    Biochemical Pharmacology Laboratory, Sheba Medical Center, Tel Hashome, Israel.

    Pseudohypoparathyroidism type Ia (PHP-Ia) is a hereditary disease characterized by resistance to PTH and other hormones that act via cAMP. Patients have deficient activity of Gs alpha, the alpha subunit of the G protein, which couples hormone receptors to stimulation of adenylate cyclase. We describe two new mutations discovered in two sporadic patients with PHP-Ia. Using genomic DNA, we have amplified exons 2-13 of the Gs alpha gene (GNAS1) by PCR, and sequenced the resulting products. Both patients had Albright's hereditary osteodystrophy, resistance to multiple hormones, and deficient Gs alpha activity. In the first patient, a deletion of a C in exon 5 at codon 115 was found. In the second patient, an insertion of a C in exon 10 at codon 267 was detected. Both these heterozygous mutations cause frameshift, and predict decreased production of Gs alpha. This report adds two new Gs alpha mutations to the known ten mutations recently described.

    Human genetics 1996;97;1;73-5

Pubmed - other

  • Pseudohypoparathyroidism: history of the disease.

    de Sanctis L

    Department of Pediatric Sciences, University of Torino, Italy. luisa.desanctis@unito.it

    Journal of pediatric endocrinology & metabolism : JPEM 

  • Intragenic GNAS deletion involving exon A/B in pseudohypoparathyroidism type 1A resulting in an apparent loss of exon A/B methylation: potential for misdiagnosis of pseudohypoparathyroidism type 1B.

    Fernandez-Rebollo E, García-Cuartero B, Garin I, Largo C, Martínez F, Garcia-Lacalle C, Castaño L, Bastepe M and Pérez de Nanclares G

    Endocrinology and Diabetes Research Group, Hospital de Cruces, 48903 Barakaldo, Bizkaia, Spain.

    Context: Several endocrine diseases that share resistance to PTH are grouped under the term pseudohypoparathyroidism (PHP). Patients with PHP type Ia show additional hormone resistance, defective erythrocyte G(s)alpha activity, and dysmorphic features termed Albright's hereditary osteodystrophy (AHO). Patients with PHP-Ib show less diverse hormone resistance and normal G(s)alpha activity; AHO features are typically absent in PHP-Ib. Mutations affecting G(s)alpha coding exons of GNAS and epigenetic alterations in the same gene are associated with PHP-Ia and -Ib, respectively. The epigenetic GNAS changes in familial PHP-Ib are caused by microdeletions near or within GNAS but without involving G(s)alpha coding exons.

    Objective: We sought to identify the molecular defect in a patient who was diagnosed with PHP-Ia based on clinical presentation (hormone resistance and AHO) but displayed the molecular features typically associated with PHP-Ib (loss of methylation at exon A/B) without previously described genetic mutations.

    Methods: Microsatellite typing, comparative genome hybridization, and allelic dosage were performed for proband and her parents.

    Results: Comparative genome hybridization revealed a deletion of 30,431 bp extending from the intronic region between exons XL and A/B to intron 5. The same mutation was also demonstrated, by PCR, in the patient's mother, but polymorphism and allele dosage analyses indicated that she had this mutation in a mosaic manner.

    Conclusion: We discovered a novel multiexonic GNAS deletion transmitted to our patient from her mother who is mosaic for this mutation. The deletion led to different phenotypic manifestations in the two generation and appeared, in the patient, as loss of GNAS imprinting.

    Funded by: NIDDK NIH HHS: R01 DK073911, R01 DK073911-02, R01DK073911

    The Journal of clinical endocrinology and metabolism 2010;95;2;765-71

  • Pseudohypoparathyroidism and GNAS epigenetic defects: clinical evaluation of albright hereditary osteodystrophy and molecular analysis in 40 patients.

    Mantovani G, de Sanctis L, Barbieri AM, Elli FM, Bollati V, Vaira V, Labarile P, Bondioni S, Peverelli E, Lania AG, Beck-Peccoz P and Spada A

    Unità di Endocrinologia, Padiglione Granelli, Fondazione Ospedale Maggiore Instituto di Ricovero e Cura a Carattere Scientifico, Via Francesco Sforza, 35, 20122 Milano, Italy. giovanna.mantovani@unimi.it

    Context: The two main subtypes of pseudohypoparathyroidism (PHP), PHP-Ia and -Ib, are caused by mutations in GNAS exons 1-13 and methylation defects in the imprinted GNAS cluster, respectively. PHP-Ia patients show Albright heredita 1f40 ry osteodystrophy (AHO) and resistance toward PTH and additional hormones, whereas PHP-Ib patients do not have AHO, and hormone resistance appears to be limited to PTH and TSH. Recently, methylation defects have been detected in few patients with PHP and mild AHO, indicating a molecular overlap between the two forms.

    Objectives: The aim of the study was to screen patients with clinically diagnosed PHP-Ia for methylation defects and to investigate the presence of correlations between the molecular findings and AHO severity.

    We investigated differential methylation of GNAS regions and STX16 microdeletions in genomic DNA from 40 patients with sporadic AHO and multihormone resistance, with no mutations in Gsalpha-coding GNAS exons.

    Results: Molecular analysis showed GNAS cluster imprinting defects in 24 of the 40 patients analyzed. No STX16 deletion was detected. The presence of imprinting defects was not associated with the severity of AHO or with specific AHO signs.

    Conclusions: We report the largest series of the literature of patients with clinical AHO and multihormone resistance and no mutation in the Gsalpha gene. Our findings of frequent GNAS imprinting defects further confirm the existence of an overlap between molecular and clinical features of PHP-Ia and PHP-Ib and highlight the necessity of a new clinical classification of the disease that takes into account the recent knowledge on the molecular basis underlying these defects.

    The Journal of clinical endocrinology and metabolism 2010;95;2;651-8

  • United detection GNAS and TSHR mutations in subclinical toxic multinodular goiter.

    Liu C, Yang J, Wang F, Wu C and Zhou M

    Department of Ultrasound,The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.

    The aim of the study was to investigate whether the mutations of the GNAS gene and thyroid-stimulating hormone receptor (TSHR) gene were a potential molecular biological mechanism for subclinical toxic multinodular goiter (sTMG) and to evaluate the association of these mutations with the clinicopathological features of these disorders.Forty-four patients with sTMG and 20 controls(multinodular goiter) from Heilongjiang province of China who underwent subtotal thyroidectomy were recruited. Genes' mutations were analyzed by direct DNA sequencing of the polymerase chain reaction-amplified the parts of exons. In sTMG group, three mutations at GNAS gene were identified in seven patients (15.9%). Six mutations at TSHR gene were identified in 14 patients (31.8%). Mutation positivity of TSHR gene had statistically significant by comparison of two groups. In sTMG group, the mutation positivity of patients with serum TSH level below 0.1 microU/ml and above 0.01 microU/ml is obviously different (P < 0.05) at TSHR gene. However, these statistically significant differences were both not being seen at GNAS gene, and patients with nodules before universal salt iodization (USI)and after USI (P > 0.05). Mutation positivity of TSHR gene has a relation with sTMG. It is more probable that serum TSH level play an important role in mutagenesis.

    European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery 2010;267;2;281-7

  • Association of the GNAS1 T393C polymorphism with tumor stage and survival in gastric cancer.

    Alakus H, Mönig SP, Warnecke-Eberz U, Alakus G, Winde G, Drebber U, Schmitz KJ, Schmid KW, Riemann K, Siffert W, Bollschweiler E, Hölscher AH and Metzger R

    Department of General, Visceral and Cancer Surgery, Center for Integrated Oncology, University Hospital of Cologne, Kerpener Str. 62, D-50937 Cologne, Germany.

    Aim: To analyze the impact of the GNAS1 T393C polymorphism on prognosis and histopathology of gastric cancer.

    Methods: Genomic DNA was extracted from paraffin-embedded tissues of 122 patients with primary gastric carcinoma and from the blood of 820 healthy white individuals. Allelic discrimination was performed by quantitative real-time polymerase chain reaction. Genotyping was correlated with histopathologic parameters and with overall survival according to the Kaplan-Meier approach and with multivariate analysis by multiple stepwise regression.

    Results: Thirty-nine (32%) patients displayed a CC genotype, 57 (46.7%) a CT genotype and 26 (21.3%) a TT genotype. The frequency of the C allele (fC) in the patient group was 0.55, which was not significantly different from that of healthy blood donors. The distribution was compatible with the Hardy-Weinberg equilibrium. Analysis of clinicopathological parameters did not show any significant correlation of the T393C genotype with gender (P = 0.50), differentiation (P = 0.29), pT-category (P = 0.19), pN-category (P = 0.30), pM-category (P = 0.25), R-category (P = 0.95), the classifications according to WHO (P = 0.34), Laurén (P = 0.16), Goseki (P = 1.00) and Ming (P = 0.74). Dichotomization between C+ (CC+CT) and C-genotypes (TT), however, revealed significantly more advanced tumor stages (P = 0.023) and lower survival rates (P = 0.043) for C allele carriers.

    Conclusion: The present study provides strong evidence to suggest that the GNAS1 T393C allele carrier status influences tumor progression and survival in gastric cancer with higher tumor stages and a worse outcome for C allele carriers.

    World journal of gastroenterology 2009;15;48;6061-7

  • Stimulatory heterotrimeric G protein augments gamma ray-induced apoptosis by up-regulation of Bak expression via CREB and AP-1 in H1299 human lung cancer cells.

    Choi YJ, Kim SY and Oh JM

    Department of Biochemistry and Molecular Biology, Laboratory of Cellular Signaling, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799, Korea.

    Stimulatory heterotrimeric GTP-binding proteins (Gs protein) stimulate cAMP generation in response to various signals, and modulate various cellular phenomena such as proliferation and apoptosis. This study aimed to investigate the effect of Gs proteins on gamma ray-induced apoptosis of lung cancer cells and its molecular mechanism, as an attempt to develop a new strategy to improve the therapeutic efficacy of gamma radiation. Expression of constitutively active mutant of the alpha subunit of Gs (GalphasQL) augmented gamma ray-induced apoptosis via mitochondrial dependent pathway when assessed by clonogenic assay, FACS analysis of PI stained cells, and western blot analysis of the cytoplasmic translocation of cytochrome C and the cleavage of caspase-3 and ploy(ADP-ribose) polymerase (PARP) in H1299 human lung cancer cells. GalphasQL up-regulated the Bak expression at the levels of protein and mRNA. Treatment with inhibitors of PKA (H89), SP600125 (JNK inhibitor), and a CRE-decoy blocked GalphasQL-stimulated Bak reporter luciferase activity. Expression of GalphasQL increased basal and gamma ray-induced luciferase activity of cAMP response element binding protein (CREB) and AP-1, and the binding of CREB and AP-1 to Bak promoter. Furthermore, prostaglandin E2, a Galphas activating signal, was found to augment gamma ray-induced apoptosis, which was abolished by treatment with a prostanoid receptor antagonist. These results indicate that Galphas augments gamma ray-induced apoptosis by up-regulation of Bak expression via CREB and AP-1 in H1299 lung cancer cells, suggesting that the efficacy of radiotherapy of lung cancer may be improved by modulating Gs signaling pathway.

    Experimental & molecular medicine 2009;41;8;592-600

  • Effect of 393T>C polymorphism of GNAS1 gene on dobutamine response in Chinese healthy subjects.

    Mao YM, Liu ZQ, Chen BL, Guo D, Han CT, Yang LJ, Wang SY, Fan L and Zhou HH

    Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Central South University, Changsha, Hunan 410078, People's Republic of China.

    The purpose of this study was to characterize the functional consequences of the 393T>C polymorphism of the GNAS1 gene in vivo. PCR-RFLP assays were used to identify GNAS1 and beta 1-adrenoceptor genotypes. The heart rate (HR), blood pressure, left ventricular fractional shortening (LVFS), and left ventricular ejection fraction (LVEF) were determined in different genotypes through a modified dobutamine stress echocardiography protocol. Our results showed that individuals with homozygous or heterozygous C393 had an increased cardiovascular agonistic response to dobutamine, and the increases from baseline in LVFS at the 3 dosage levels of dobutamine were 19.3% +/- 1.0% versus 32.0% +/- 2.9%, 36.7% +/- 3.1% versus 41.3% +/- 4.1%, and 51.7% +/- 3.3% versus 58.7% +/- 2.6% in T393 homozygotes and C393 homozygotes or heterozygotes, respectively (P = .026). Significant differences were also found between these 2 groups with the increases from baseline in LVEF (P = .007) and SBP (P = .048). In addition, there were significant differences in the increases from atopine in LVFS (P = .011), LVEF (P = .004), and SBP (P = .046) between the T393 homozygotes and C393 homozygotes or heterozygotes. The change of LVEF in C393 homozygous was higher than that in T393 homozygous at the dose of 40 microg/kg/min (28.9% +/- 4.0% vs 36.4% +/- 2.1%; 95% CI, 18.8%-38.9%; P = .046). These data suggested that the 393T>C polymorphism of GNAS1 was functionally relevant in vivo.

    Journal of clinical pharmacology 2009;49;8;929-36

  • Identification of a novel GNAS mutation for pseudohypoparathyroidism in a Chinese family.

    Sun LH, Cui B, Zhao HY, Tao B, Wang WQ, Li XY, Ning G and Liu JM

    Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Rui-jin Hospital, Shanghai Jiao-tong University School of Medicine, Shanghai, 200025, China.

    Pseudohypoparathyroidism (PHP) is a heterogeneous group of diseases characterized by hormone resistance to receptors that stimulate adenylate cyclase. PHP-Ia patients show specific Gs-alpha protein deficiency, PTH/TSH/gonadotropin resistance, and a phenotype characterized by Albright hereditary osteodystrophy (AHO). Many heterozygous mutations in the GNAS gene encoding the Gs protein have been identified in PHP-Ia. We describe two boys with hypocalcemia and elevated serum levels of PTH in a Chinese family. The 13 exons of the GNAS gene were amplified using 15 pairs of GNAS-specific primers and analyzed by direct sequencing. We found a novel frame shift mutation in exon 11 of the GNAS gene identified in both of the two boys and their mother. This report provides another example of a Gs-alpha mutation leading to PHP.

    Endocrine 2009;36;1;25-9

  • Abnormalities of cAMP signaling are present in adrenocortical lesions associated with ACTH-independent Cushing syndrome despite the absence of mutations in known genes.

    Bimpaki EI, Nesterova M and Stratakis CA

    Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), NIH, Building 10, CRC (East Laboratories), Room 1-3330, 10 Center Drive, MSC1103, Bethesda, Maryland 20892, USA.

    Context: Bilateral adrenal hyperplasias (BAHs) may be caused by mutations of genes that code for molecules that participate in cAMP signaling. Little is known about cAMP signaling in adrenal lesions associated with ACTH-independent Cushing syndrome (AICS) that do not harbor mutations in known genes.

    Objective: We assessed the cAMP-signaling pathway by enzymatic and molecular studies.

    Design: Samples from 27 patients (ages 5-60 years) were studied and compared with normal adrenocortical tissue (n=4) and aldosterone-producing adenomas (APA, n=5). All samples were sequenced for GNAS, PRKAR1A, PDE11A, and PDE8B sequencing defects. cAMP levels and binding, protein kinase A, and phosphodiesterase (PDE) activities were assayed. Immunohistochemistry was used for certain studies and the phosphorylation status of CREB was studied.

    Patients: A total of 36 samples from patients were used.

    Results: Cortisol-producing adenomas (CPAs) and other lesions that were GNAS, PRKAR1A, PDE11A, and PDE8B gene mutation-negative were compared with PRKAR1A mutation-positive lesions, normal tissue, and APAs; abnormalities of the cAMP-signaling pathway were found in both BAHs and CPAs. Interestingly, mutation-negative CPAs had significantly decreased PDE activity.

    Conclusion: Lesions of the adrenal associated with AICS, independently of their GNAS, PRKAR1A, PDE11A, and PDE8B mutation status, have functional abnormalities of cAMP signaling. It is probable that epigenetic events or additional defects of genes involved in this pathway are responsible for this phenomenon.

    Funded by: Intramural NIH HHS: ZIA HD000642-13; NICHD NIH HHS: Z01 HD000642, Z01-HD-000642-04

    European journal of endocrinology 2009;161;1;153-61

  • A novel functional haplotype in the human GNAS gene alters Galphas expression, responsiveness to beta-adrenoceptor stimulation, and peri-operative cardiac performance.

    Frey UH, Adamzik M, Kottenberg-Assenmacher E, Jakob H, Manthey I, Broecker-Preuss M, Bergmann L, Heusch G, Siffert W, Peters J and Leineweber K

    Klinik für Anästhesiologie und Intensivmedizin, Universität Duisburg-Essen, D-45122 Essen, Germany. ulrich.frey@uk-essen.de

    Aims: Cardiac overexpression of the beta-adrenoceptor-coupled G-protein subunit Galphas in mice enhances inotropic responses to sympathetic stimulation, but evokes cardiomyopathy with increasing age. We tested whether functional single nucleotide polymorphisms (SNPs) in the human Galphas (GNAS) gene modulate Galphas expression and assessed functional consequences.

    Sequencing the promoter and intron 1 of GNAS revealed 11 SNPs resulting in three common haplotypes. Haplotype *3 constructs exhibited significantly higher promoter activity than haplotypes *1 and *2, resulting in a more than 50% higher Galphas mRNA expression in homozygous *3 carriers (*3/*3) than in heterozygous (*3/-) and negative *3 (-/-) carriers (P = 0.002). Basal, Galphas- (via NaF and GTP) and isoproterenol-stimulated adenylyl cyclase (AC) activities were also significantly higher in *3/*3 than in *3/- and -/- carriers. In contrast, direct AC activation via forskolin was independent of GNAS haplotypes. Furthermore, haemodynamic measurements in 137 coronary artery bypass patients revealed a higher cardiac index in *3/*3 carriers than in *3/- and -/- carriers (P = 0.025) associated with a lower NYHA functional class (P = 0.040) and serum NT-proBNP concentrations (P = 0.002).

    Conclusion: SNPs in regulatory regions of GNAS impact upon Galphas expression and stimulated cAMP formation in human hearts in vitro and upon cardiac performance in vivo.

    European heart journal 2009;30;11;1402-10

  • The T393C polymorphism of the Galphas gene (GNAS1) is associated with the course of Graves' disease.

    Glowacka D, Loesch C, Johnson KT, Mann K, Esser J, Morgenthaler NG, Siffert W, Schmid KW and Eckstein AK

    Department of Ophthalmology, University Hospital of Essen, University of Duisburg-Essen, Germany.

    Genotypes of the T393C SNP of GNAS1, a gene that encodes for the Galphas subunit of G proteins have been significantly associated with the clinical course in a variety of cancers. Since this SNP may also influence the course of Graves' disease (GD) and, especially, Graves' ophthalmopathy (GO), we determined genotype and allele frequency in a series of 359 patients, which were referred to our clinic within 6 months of the onset of GO. Among them, 336 patients also suffered from associated hyperthyroidism. Data on relapse and remission rates 12 months after termination of a 1 year antithyroid drug th 1808 erapy was available for 276 patients. As controls, 820 healthy individuals were recruited. Our data suggest that the T393C SNP does not represent a risk factor for the development of both GD and GO. It was, however, significantly associated with the course of hyperthyroidism (p=0.013) and a similar trend was evident for the course of GO (p=0.093). Homozygous TT carriers showed a significantly increased risk (p=0.03) for hyperthyroidism to relapse (OR 2.4; 95% CI 1.1-5.4). Also, the TT genotype was associated with significantly increased serum TRAb levels (CC+CT: 5.4 IU/l vs. TT: 9.3 IU/l). This is probably caused by increased G-Protein susceptibility to TSHR-mediated stimulation through TRAb. Genotyping of the T393C SNP of GNAS1 may become a useful additional tool to predict the clinical course of GD and GO. This may allow the clinician to identify patients at risk for more severe courses of disease and to come to more timely decisions for treatment.

    Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme 2009;41;6;430-5

  • Analysis of GNAS1 and PRKAR1A gene mutations in human cardiac myxomas not associated with multiple endocrine disorders.

    Mantovani G, Bondioni S, Corbetta S, Menicanti L, Rubino B, Peverelli E, Labarile P, Dall'Asta C, Ambrosi B, Beck-Peccoz P, Lania AG and Spada A

    Endocrine Unit, Department of Medical Sciences, Fondazione Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena IRCCS, 20122 Milan, Italy. giovanna.mantovani@unimi.it

    Cardiac myxomas are rare tumors that usually occur as sporadic lesions or,more rarely, in the familial form,mostly in the context of Carney complex (CNC). The molecular basis for the development of cardiac myxomas is unclear. However, somatic activating mutations in the GNAS1 gene (the gsp oncogene) are detected in the myocardium ofMcCune-Albright syndrome patients while germ-line mutations in the PRKAR1A gene are associated with CNC and familial myxomas. We investigated the presence of activating missense mut cc0 ations in the GNAS1 gene as well as of inactivating mutations in PRKAR1A in 29 sporadically occurring cardiac myxomas. No gsp and no PRKAR1A mutations were found by direct sequencing of PCR products amplified from tumoral DNA. This is the first study including a large series of sporadic, isolated cardiac myxomas and showing that these cardiac neoplasms do not share the same mutations found in familial forms.

    Journal of endocrinological investigation 2009;32;6;501-4

  • GNAS1 T393C polymorphism is associated with histopathological response to neoadjuvant radiochemotherapy in esophageal cancer.

    Alakus H, Warnecke-Eberz U, Bollschweiler E, Mönig SP, Vallböhmer D, Brabender J, Drebber U, Baldus SE, Riemann K, Siffert W, Hölscher AH and Metzger R

    Department of General, Visceral and Cancer Surgery, Center for Integrated Oncology, University Hospital of Cologne, Cologne, Germany.

    Recent studies have shown an association between the GNAS1 T393C polymorphism and clinical outcome for various solid tumors. In this study, we genotyped 51 patients from an observational trial on cisplatin/5-FU-based neoadjuvant radiochemotherapy of locally advanced esophageal cancer (cT2-4, Nx, M0) and genotyping was correlated with histomorphological tumor regression. The C-allele frequency in esophageal cancer patients was 0.49. Pearson's chi(2)-test showed a significant (P<0.05) association between tumor regression grades and T393C genotypes. Overall, 63% of the patients in the T-allele group (TT+CT) were minor responders with more than 10% residual vital tumor cells in resection specimens, whereas T(-) genotypes (CC) showed a major histopathological response with less than 10% residual vital tumor cells in 80%. The results support the role of the T393C polymorphism as a predictive molecular marker for tumor response to cisplatin/5-FU-based radiochemotherapy in esophageal cancer.

    The pharmacogenomics journal 2009;9;3;202-7

  • Genetic insight into syncopal tilted population with severe clinical presentation.

    Lelonek M, Pietrucha T, Matyjaszczyk M and Goch JH

    Department of Cardiology, Chair of Cardiology and Cardiac Surgery, Medical University of Lodz, Poland. mlelonek@poczta.fm

    Unlabelled: An impairment of cardiovascular reflexes may be the result of functional alterations in the G proteins intracellular signaling produced by functional genes' polymorphisms. The aim was to evaluate the relationships between single nucleotide polymorphisms in genes encoding G-proteins signaling pathways and syncopal patients with severe clinical manifestation.

    From 307 syncopal patients free from any other diseases 83 (27%) had at least one malignant episode of syncope with a significant injury as fractures. There was 1.9 malignant spells per patient. All patients were tilted and genotyped by polymerase chain reaction followed by restriction fragment length polymorphism method. 74 healthy volunteers with negative history of syncope constituted the control group were also genotyped. Following polymorphisms were detected: C393T in gene encoding the alfa-subunit of Gs-protein (GNAS1), C825T of gene for G-protein beta 3 subunit (GNB3) and C1114G for the gene of cardiac regulator of G-protein signaling (RGS2). We found an association with lower risk of malignant syncope in positive tilting patients during passive phase of the test compared to NTG-enhanced (OR 0.38; 95% CI 0.15-0.95; P=0.04). No difference between healthy controls and patients in the alleles frequency was found (P>0.05). Neither the 393T allele of GNAS1 and 825T allele of GNB3 nor 1114G allele of RGS2 was associated with enhanced risk of severe clinical manifestation (P>0.05).

    Conclusions: The studied single nucleotide polymorphisms of genes encoding G-proteins signaling pathways seem to be not connected with the severe clinical manifestation of syncope.

    Autonomic neuroscience : basic & clinical 2009;147;1-2;97-100

  • GNAS1 mutations occur more commonly than previously thought in intramuscular myxoma.

    Delaney D, Diss TC, Presneau N, Hing S, Berisha F, Idowu BD, O'Donnell P, Skinner JA, Tirabosco R and Flanagan AM

    Department of Histopathology, Royal National Orthopaedic Hospital NHS Trust, Stanmore, Middlesex, UK.

    Mutation detection plays an important role in diagnostic pathology, not only in providing a tissue diagnosis, but also in predicting response to antitumourigenic agents. However, mutation detection strategies are often hampered by masking of mutant alleles by wild-type sequences. Coamplification at lower denaturation temperature PCR (COLD-PCR) reportedly increases the proportion of rare variant sequences in a wild-type background by using PCR cycles in which the denaturation temperature is reduced to favour product formation with lower melt temperatures and heteroduplexes arising from minor variants. Intramuscular myxoma is a rare benign soft tissue neoplasm that occurs sporadically and less commonly in association with fibrous dysplasia (Mazabraud's syndrome). Fibrous dysplasia results from activating GNAS1 mutations, and the same mutations have been identified in small numbers of intramuscular myxoma. The aim of the study was primarily to establish whether COLD-PCR is more sensitive than conventional PCR; this was achieved by testing for GNAS1 mutations in intramuscular myxomas using the two methodologies. Mutations were detected in 8 of 28 (29%) cases of intramuscular myxomas using conventional PCR followed by mutation-specific restriction enzyme digestion (PCR-MSRED) whereas 17 of 28 (61%) mutations were detected using COLD-PCR/MSRED. Mutations were detected in two cases where a diagnosis of low-grade myxofibrosarcoma had been favoured over intramuscular myxoma. No mutations were detected in an additional 9 low-grade and 19 high-grade myxofibrosarcomas, and another 40 control samples. This study shows the power of COLD-PCR compared with conventional PCR in mutation detection, and shows that GNAS1 mutation detection increases diagnostic accuracy when distinguishing between intramuscular myxoma and low-grade myxofibrosarcoma.

    Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 2009;22;5;718-24

  • Genetic mutations associated with cigarette smoking in pancreatic cancer.

    Blackford A, Parmigiani G, Kensler TW, Wolfgang C, Jones S, Zhang X, Parsons DW, Lin JC, Leary RJ, Eshleman JR, Goggins M, Jaffee EM, Iacobuzio-Donahue CA, Maitra A, Klein A, Cameron JL, Olino K, Schulick R, Winter J, Vogelstein B, Velculescu VE, Kinzler KW and Hruban RH

    Department of Oncology, The Sol Goldman Pancreatic Cancer Research Center, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21231, USA.

    Cigarette smoking doubles the risk of pancreatic cancer, and smoking accounts for 20% to 25% of pancreatic cancers. The recent sequencing of the pancreatic cancer genome provides an unprecedented opportunity to identify mutational patterns associated with smoking. We previously sequenced >750 million bp DNA from 23,219 transcripts in 24 adenocarcinomas of the pancreas (discovery screen). In this previous study, the 39 genes that were mutated more than once in the discovery screen were sequenced in an additional 90 adenocarcinomas of the pancreas (validation screen). Here, we compared the somatic mutations in the cancers obtained from individuals who ever smoked cigarettes (n = 64) to the somatic mutations in the cancers obtained from individuals who never smoked cigarettes (n = 50). When adjusted for age and gender, analyses of the discovery screen revealed significantly more nonsynonymous mutations in the carcinomas obtained from ever smokers (mean, 53.1 mutations per tumor; SD, 27.9) than in the carcinomas obtained from never smokers (mean, 38.5; SD, 11.1; P = 0.04). The difference between smokers and nonsmokers was not driven by mutations in known driver genes in pancreatic cancer (KRAS, TP53, CDKN2A/p16, and SMAD4), but instead was predominantly observed in genes mutated at lower frequency. No differences were observed in mutations in carcinomas from the head versus tail of the gland. Pancreatic carcinomas from cigarette smokers harbor more mutations than do carcinomas from never smokers. The types and patterns of these mutations provide insight into the mechanisms by which cigarette smoking causes pancreatic cancer.

    Funded by: NCI NIH HHS: CA62924, P50 CA062924, P50 CA062924-08S30011, P50 CA062924-090011, P50 CA062924-160011, R01 CA039416, R37 CA043460

    Cancer research 2009;69;8;3681-8

  • Bcl2 -938C/A polymorphism carries increased risk of biochemical recurrence after radical prostatectomy.

    Hirata H, Hinoda Y, Kikuno N, Suehiro Y, Shahryari V, Ahmad AE, Tabatabai ZL, Igawa M and Dahiya R

    Department of Urology, San Francisco Veterans Affairs Medical Center and University of California-San Francisco, San Francisco, California, USA.

    Purpose: Approximately 10% to 26% of patients show biochemical failure after radical prostatectomy or radiation therapy. The importance of cell cycle and apoptosis pathways in prostate cancer has been reported. However, to our knowledge there is currently no information on the role of apoptosis and cell cycle related gene polymorphisms in prostate cancer cases. We investigated several polymorphisms related to the cell cycle and apoptosis, and their role in biochemical failure after radical prostatectomy.

    We genotyped 6 single nucleotide polymorphisms in 6 genes, including p53 (rs1042522), p21 (rs1801270), MDM2 (rs2279744), PTEN (rs701848), GNAS1 (rs7121) and bcl2 (rs2279115), using polymerase chain reaction-restriction fragment length polymorphism and direct DNA sequencing in 140 patients with prostate cancer and 167 age matched controls. The association of polymorphic variants with prostate specific antigen failure in patients with prostate cancer was analyzed by Kaplan-Meier curves.

    Results: A significant increase in the frequency of the C/C genotype of GNAS1 rs7121 was observed in patients compared with controls. Interestingly we found a significant difference in biochemical recurrence-free time between the bcl2 C/C and C/A+A/A genotypes. It was also noted that the bcl2 C/C genotype was an independent risk factor for biochemical recurrence after radical prostatectomy on multivariate analysis. There was no statistical difference in the genotype distributions of the other genes between patients and controls.

    Conclusions: To our knowledge this is the first report documenting that bcl2 promoter region -938 C/C genotype carriers more frequently show biochemical recurrence than -938C/A+A/A carriers.

    Funded by: NCI NIH HHS: R01CA101844, R01CA108612, R01CA111470; NIDDK NIH HHS: T32-DK07790

    The Journal of urology 2009;181;4;1907-12

  • Pseudohypoparathyroidism type IA (PHP-Ia): maternally inherited GNAS gene mutation.

    Semiz S, Duzcan F, Candemir M, Caner V, Thiele S, Semiz E and Hiort O

    Department of Pediatrics, Faculty of Medicine, Pamukkale University, Denizli, Turkey.

    Journal of pediatric endocrinology & metabolism : JPEM 2009;22;2;107-8

  • Prevalence of gsp oncogene in somatotropinomas and clinically non-functioning pituitary adenomas: our experience.

    Taboada GF, Tabet AL, Naves LA, de Carvalho DP and Gadelha MR

    Serviço de Endocrinologia do Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, 555/101 Ipanema, Rio de Janeiro 22421-020, Brazil.

    The purpose of the present study is to evaluate the prevalence of the gsp oncogene in Brazilian patients harboring somatotropinomas and non-functioning pituitary adenomas (NFPA). Patients and methods Deoxyribonucleic acid was extracted from 54 somatotropinomas and 14 NFPA. Exons 8 and 9 (including codons 201 and 227, respectively) of the GNAS gene were amplified by polymerase chain reaction (PCR). The PCR products were then purified and sequenced using the same primers. Results The gsp oncogene was found in nine tumors (eight somatotropinomas). The prevalence among somatotropinomas was 15% and among NFPA was 7%. The mutation was found in codon 201 in eight tumors and in codon 227 in one tumor (a somatotropinoma). No differences were found in age, sex, GH, and IGF-I levels or tumor volume at diagnosis between gsp+ and gsp- patients. Conclusion We found a lower than expected prevalence of gsp mutations in somatotropinomas and a similar prevalence in NFPA compared to previous studies from other countries.

    Pituitary 2009;12;3;165-9

  • Prevalence of TSH receptor and Gsalpha mutations in 45 autonomously functioning thyroid nodules in Japan.

    Nishihara E, Amino N, Maekawa K, Yoshida H, Ito M, S, Fukata S and Miyauchi A

    Kuma Hospital, Chuo-ku, Kobe, Hyogo, Japan. nishihara@kuma-h.or.jp

    Somatic mutations of the thyrotropin receptor (TSHR) gene and the gene encoding the alpha subunit of the stimulatory GTP-binding protein (Gsalpha) are the main cause for autonomously functioning thyroid nodules (AFTN) in iodine-deficient regions of the world. In iodine-sufficient regions, including Japan, the genetic relevance of AFTN is unclear. In a series of 45 Japanese subjects with AFTN, exons 9 and 10 of the TSHR and exons 7-10 of Gsalpha , where the activating mutations have been found, were analyzed using direct sequencing. We found 29 somatic mutations: 22 in the TSHR gene and 7 in the Gsalpha gene. The most frequent mutation in TSHR was Met453Thr (10 cases), followed by clustered residues from codons 630 through 633 on TSHR (7 cases). Mutations of Gsalpha were detected at codon 201 in 5 cases and at codon 227 in 2 cases. No patients had coexistent TSHR and Gsalpha mutations in the same nodule. All mutated residues but one, which was deleted at codon 403 on the TSHR gene, are constitutively active. The prevalences of a germline polymorphism of Asp727Glu on the TSHR gene and incidental papillary thyroid carcinoma in thyroid surgical specimens were similar to those reported in other studies. In the present study, more than half of the cases with AFTN had a somatic activating mutation either of the TSHR or Gsalpha gene, despite their high iodine intake.

    Endocrine journal 2009;56;6;791-8

  • Galphaq reduces cAMP production by decreasing Galphas protein abundance.

    Tang T, Gao MH, Miyanohara A and Hammond HK

    Department of Medicine , University of California San Diego, La Jolla, California 92039, USA.

    The heterotrimeric guanine nucleotide-binding protein Galphaq transduces signals from heptahelical transmembrane receptors (e.g., alpha(1)-adrenergic, endothelin 1A, and angiotensin II) to stimulate generation of inositol-1,4,5-trisphosphate and diacylglycerol. In addition, Galphaq decreases cAMP production, through unknown mechanisms, and thus affects physiological responsiveness of cardiac myocytes and other cells. Here, we provide evidence that Galphaq expression increases Galphas ubiquitination, decreases Galphas protein content, and impairs basal and beta(1)-adrenergic receptor-stimulated cAMP production. These biochemical and functional changes are associated with Akt activation. Expression of constitutively active Akt also decreases Galphas protein content and inhibits basal and beta(1)-adrenergic receptor-stimulated cAMP production. Akt knockdown inhibits Galphaq-induced reduction of Galphas protein. In addition, MDM2, an E3 ubiquitin ligase, binds Galphas and promotes its degradation. Therefore, increased expression of Galphaq decreases cAMP production through Akt-mediated Galphas protein ubiquitination and proteasomal degradation.

    Funded by: NHLBI NIH HHS: HL081741, HL088426, HL66941, P01 HL066941, P01 HL066941-08, R01 HL081741, R01 HL081741-04, R01 HL088426, R01 HL088426-01A1

    Biochemical and biophysical research communications 2008;377;2;679-84

  • A functional GNAS promoter polymorphism is associated with altered weight loss during short-term fasting.

    Frey UH, Michalsen A, Merse S, Dobos GJ and Siffert W

    Institut für Pharmakogenetik, Universitätsklinikum, Essen, Germany. ulrich.frey@uk-essen.de

    In mice, heterozygous knockout of the stimulatory G protein Gas results in obesity which suggests a key role of Gas in body weight regulation. We have recently identified a functional G(-1211)A promoter polymorphism in the human GNAS gene encoding Gas, the GG genotype being associated with increased promoter activity and lipolysis in vitro and increased weight loss capacity in vivo. The present study aimed to independently confirm these results. We genotyped 87 subjects who underwent a 7-day modified fast for the GNAS polymorphism and recorded weight, hunger, and mood. While both mood and hunger were not dependent on genotype, GNAS genotypes were significantly associated with weight loss (GG: -5.0 +/- 1.5 kg, n = 28; AG: -4.2 +/- 1.1 kg, n = 50; AA: -3.2 +/- 1.2, n = 9; p = 0.0003). The present study reconfirms our earlier reported findings and suggests that GNAS genotypes also influence weight loss during short-term fasting. related to a low vascular density (CD31 expression) in CDC.

    European journal of medical research 2008;13;12;576-8

  • The GNAS1 T393C polymorphism predicts survival in patients with advanced squamous cell carcinoma of the larynx.

    Lehnerdt GF, Franz P, Winterhoff S, Bankfalvi A, Grehl S, Lang S, Schmid KW, Siffert W, Jahnke K and Frey UH

    Department of Otorhinolaryngology, University of Duisburg-Essen, Essen, Germany. goetz.lehnerdt@uni-due.de

    In previous studies, we have demonstrated that the T-allele of a specific single nucleotide polymorphism (SNP) in the Galphas gene (T393C) correlates with increased Galphas expression and hence apoptosis. The T-allele was associated with a favorable outcome in a variety of human cancers, for example, carcinoma of the urinary bladder, kidney, colorectal, oro- and hypopharynx.

    The prognostic value of the T393C SNP was retrospectively evaluated in an unselected series of patients treated with curative intent for laryngeal squamous cell carcinomas including all tumor stages with different therapeutic regimens.

    Methods: DNA analysis was performed using DNA from paraffin-embedded tissue samples from 157 patients (142 men, 15 women) with a median follow-up of 68 (3-143) months. The various genotypes were correlated with the overall survival.

    Results: Survival was significantly dependent on the T393C genotype in advanced American Joint Committee on Cancer (AJCC) stages (III-IV) with an apparent gene-dose effect (P = .0437). Five-year survival rates were 76% for TT, 49% for TC, and 43.5% for CC. In multivariate analysis including age at diagnosis, AJCC stage, grade, gender, and T393C genotypes, patients with CC genotype displayed a higher risk for death with a hazard ratio of 2.59 (95% confidence interval: 1.01-6.64, P = .047) compared with the reference group consisting of T393 homozygous individuals.

    Conclusions: The T393C SNP is a prognostic marker that could help to identify high risk patients suffering from head and neck cancer.

    The Laryngoscope 2008;118;12;2172-6

  • Association of the GNAS locus with severe malaria.

    Auburn S, Diakite M, Fry AE, Ghansah A, Campino S, Richardson A, Jallow M, Sisay-Joof F, Pinder M, Griffiths MJ, Peshu N, Williams TN, Marsh K, Molyneux ME, Taylor TE, Koram KA, Oduro AR, Rogers WO, Rockett KA, Haldar K and Kwiatkowski DP

    Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford, OX3 7BN, UK. sa3@sanger.ac.uk

    Functional studies have demonstrated an interaction between the stimulatory G protein alpha subunit (G-alpha-s) and the malaria parasite at a cellular level. Obstruction of signal transduction via the erythrocyte G-alpha-s subunit reduced invasion by Plasmodium falciparum parasites. We sought to determine whether this signal pathway had an impact at the disease level by testing polymorphisms in the gene encoding G-alpha-s (GNAS) for association with severe malaria in a large multi-centre study encompassing family and case-control studies from The Gambia, Kenya and Malawi, and a case-control study from Ghana. We gained power to detect association using meta-analysis across the seven studies, with an overall sample size approximating 4,000 cases and 4,000 controls. Out of 12 SNPs investigated in the 19 kb GNAS region, four presented signals of association (P < 0.05) with severe malaria. The strongest single-locus association demonstrated an odds ratio of 1.13 (1.05-1.21), P = 0.001. Three of the loci presenting significant associations were clustered at the 5-prime end of the GNAS gene. Accordingly, haplotypes constructed from th 1ea3 ese loci demonstrated significant associations with severe malaria [OR = 0.88 (0.81-0.96), P = 0.005 and OR = 1.12 (1.03-1.20), P = 0.005]. The evidence presented here indicates that the influence of G-alpha-s on erythrocyte invasion efficacy may, indeed, alter individual susceptibility to disease.

    Funded by: Medical Research Council: G0600230, G0600230(77610), G19/9; Wellcome Trust: 076934

    Human genetics 2008;124;5;499-506

  • Gender-dependent association of the GNAS1 T393C polymorphism with early aseptic loosening after total hip arthroplasty.

    Bachmann HS, Hanenkamp S, Kornacki B, Frey UH, Bau M, Siffert W and Wedemeyer C

    Institute of Pharmacogenetics, Medical Faculty, University of Duisburg-Essen, Hufelandstrasse 55, D-45147 Essen, Germany. hagen.bachmann@uk-essen.de

    The G-protein Galphas is involved in the physiology and pathophysiology of bone. Especially, Galphas is a key regulator of interleukin-6, which is a potent promoter of aseptic loosening. We hypothesized that the common single nucleotide polymorphism GNAS1 T393C could also affect time to aseptic loosening. Caucasian patients were genotyped for the GNAS1 T393C polymorphism. Time and median time to aseptic loosening were analyzed for dependency on GNAS1 genotypes. Time and median time were not significantly associated with genotypes. Additional analysis corrected for gender revealed, that the TT genotype was associated with significantly longer time (p = 0.048) as well as median time (p = 0.022) to aseptic loosening in female patients. In contrast to the findings in females, male TT genotype carriers had significantly shorter time (p = 0.018) and median time (p = 0.023) to aseptic loosening. Compared with TT genotype carriers heterozygous patients had a 6.25-fold lower risk with a hazard ratio of 0.160 (p = 0.016) and male patients carrying the CC genotype had an 11-fold lower risk with a hazard ratio of 0.088 (p = 0.006) in multivariate analysis. The present study suggests a significant gender-dependent role of the T393C polymorphism in aseptic loosening. The apparently contradictory results in women and men and the finding that the GNAS1 T393C genotype is an independent factor for time to aseptic loosening in male patients assigned this polymorphism as an interesting target for further investigations in bone diseases.

    Journal of orthopaedic research : official publication of the Orthopaedic Research Society 2008;26;12;1562-8

  • GNAS defects identified by stimulatory G protein alpha-subunit signalling studies in platelets.

    Freson K, Izzi B, Labarque V, Van Helvoirt M, Thys C, Wittevrongel C, Bex M, Bouillon R, Godefroid N, Proesmans W, de Zegher F, Jaeken J and Van Geet C

    Center for Molecular and Vascular Biology, University of Leuven, Herestraat 49, B-3000 Leuven, Belgium. Kathleen.freson@med.kuleuven.be

    Context: GNAS is an imprinted region that gives rise to several transcripts, antisense transcripts, and noncoding RNAs, including transcription of RNA encoding the alpha-subunit of the stimulatory G protein (Gsalpha). The complexity of the GNAS cluster results in ubiquitous genomic imprints, tissue-specific Gsalpha expression, and multiple genotype-phenotype relationships. Phenotypes resulting from genetic and epigenetic abnormalities of the GNAS region include Albright's hereditary osteodystrophy, pseudohypoparathyroidism types Ia (PHPIa) and Ib (PHPIb), and pseudopseudohypoparathyroidism (PPHP).

    Objective: The aim was to study the complex GNAS pathology by a functional test as an alternative to the generally used but labor-intensive erythrocyte complementation assay.

    We report the first platelet-based diagnostic test for Gsalpha hypofunction, supported by clinical, biochemical, and molecular data for six patients with PHPIa or PPHP and nine patients with PHPIb. The platelet test is based on the inhibition of platelet aggregation by cAMP, produced after Gsalpha stimulation.

    Results: Platelets are easily accessible, and platelet aggregation responses were found to reflect Gsalpha signaling defects in patients, in concordance with the patient's phenotype and genotype. Gsalpha hypofunction in PHPIa and PPHP patients with GNAS mutations was clearly detected by this method. Mildly decreased or normal Gsalpha function was detected in patients with PHPIb with either an overall or exon 1A-only epigenetic defect, respectively. Platelet Gsalpha expression was reduced in both PHPIb patient groups, whereas XLalphas was up-regulated only in PHPIb patients with the broad epigenetic defect.

    Conclusion: The platelet-based test is a novel tool for establishing the diagnosis of Gsalpha defects, which may otherwise be quite challenging.

    The Journal of clinical endocrinology and metabolism 2008;93;12;4851-9

  • Age-dependent demise of GNAS-mutated skeletal stem cells and "normalization" of fibrous dysplasia of bone.

    Kuznetsov SA, Cherman N, Riminucci M, Collins MT, Robey PG and Bianco P

    Craniofacial and Skeletal Diseases Branch, National Institute of Dental 18e8 and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA.

    We studied the role of somatic mosaicism in fibrous dysplasia of bone (FD) within the context of skeletal ("mesenchymal") stem cells by assessing the frequency of mutated colony forming unit-fibroblasts (CFU-Fs) from FD lesions, and in some cases, from unaffected sites, in a series of patients. There was a tight inverse correlation between the percentage mutant CFU-F versus age, suggesting demise of mutant stem cells caused by exuberant apoptosis noted in samples from young patients. In older patients, either partially or completely normal bone/marrow histology was observed. On in vivo transplantation, FD ossicles were generated only by cell strains in which mutant CFU-Fs were identified. Strains that lacked mutant CFU-F (but were mutation positive) failed to regenerate an FD ossicle. These data indicate that GNAS mutations are only pathogenic when in clonogenic skeletal stem cells. From these data, we have evolved the novel concept of "normalization" of FD. As a lesion ages, mutant stem cells fail to self-renew, and their progeny are consumed by apoptosis, whereas residual normal stem cells survive, self-renew, and enable formation of a normal structure. This suggests that activating GNAS mutations disrupt a pathway that is required for skeletal stem cell self-renewal.

    Funded by: Telethon: GGP04263

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2008;23;11;1731-40

  • Lack of involvement of the GNAS1 T393C polymorphism in prostate cancer risk in a Japanese population.

    Watanabe M, Hirokawa Y, Tsuji M, Yanagawa M, Murata T, Suzuki H, Ichikawa T, Katoh T, Sugimura Y and Shiraishi T

    Department of Pathologic Oncology, Institute of Molecular and Experimental Medicine, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Japan.

    Background: GNAS1 encodes the a-subunit of the Gs protein (Gsa), which binds GTP and stimulates adenylyl cyclase. Activating mutations lead to somatotroph, thyroid, adrenal and gonadal adenomas or the McCune-Albright syndrome and recently the T399C polymorphism in GNAS1 has been reported to be associated with malignancies. The purpose of the present case-control study with 349 Japanese prostate cancer patients and 203 urological controls was to determine whether the GNAS1 T393C polymorphism is associated with prostate cancer risk.

    The GNAS1 T393C polymorphism was examined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Odds ratios (OR) were adjusted for age using multiple logistic regression analysis with SPSS Medical Pack.

    Results: The allele frequencies were compatible with the control population in Hardy-Weinberg equilibrium with 80, 169 and 100 for GNAS1 C/C, C/T and T/T, respectively in the patients with prostate cancer, compared with 42, 94 and 67 in the controls. No association between the GNAS1 polymorphism and prostate cancer risk was apparent. The C/C genotype was more frequent among the prostate cancer patients (22.9%) than the controls (20.7%), although without significance (OR, 1.30; 95% CI, 0.80-2.12; p=0.29).

    Conclusion: This pilot study does not support involvement of the GNAS1 polymorphism in prostate cancer risk.

    Anticancer research 2008;28;6A;3711-6

  • Non-functioning pituitary adenomas infrequently harbor G-protein gene mutations.

    Ruggeri RM, Santarpia L, Curtò L, Torre ML, Galatioto M, Galatioto S, Trimarchi F and Cannavò S

    Department of Medicine and Pharmacology, Section of Endocrinology, University of Messina, 98125 Messina, Italy. rmruggeri@unime.it

    Background: Mutations of the genes encoding the alpha subunit of the stimulatory G protein (Gs) and of the inhibiting Gi2 protein (GNAS1 and GNAI2 genes, respectively) have been described in various endocrine neoplasias, including pituitary tumors.

    Aim: To search for mutations of GNAS1 and GNAI2 in a continuous series of non-functioning pituitary adenoma (NFPA) patients neurosurgically treated.

    The surgical samples of 22 patients who have been defined and characterized on a clinical, biochemical, histological, and immunohistochemical point of view have been processed for investigating the presence of the above mutations by PCR amplification of the hot spots exons 8 and 9 of GNAS1, and exons 5 and 6 of GNAI2, followed by direct sequencing. Moreover, the promoter region of GNAI2, in order to assess the prevalence of single nucleotide polymorphisms (SNP), was investigated in the same series.

    Results: A CGT>TGT mutation at codon 201 of GNAS1 gene in a single case of NFPA was found, but no mutation of GNAI2A was demonstrated.

    Conclusions: This finding suggests and confirms that G-protein mutations are rare and not crucial in NFPA development. Additionally, we found a silent SNP at codon 318 in the promoter of the Gi2alpha gene in one out of the 22 NFPA.

    Journal of endocrinological investigation 2008;31;11;946-9

  • Prevalence of mutations in TSHR, GNAS, PRKAR1A and RAS genes in a large series of toxic thyroid adenomas from Galicia, an iodine-deficient area in NW Spain.

    Palos-Paz F, Perez-Guerra O, Cameselle-Teijeiro J, Rueda-Chimeno C, Barreiro-Morandeira F, Lado-Abeal J, Galician Group for the Study of Toxic Multinodular Goitre, Araujo Vilar D, Argueso R, Barca O, Botana M, Cabezas-Agrícola JM, Catalina P, Dominguez Gerpe L, Fernandez T, Mato A, Nuño A, Penin M and Victoria B

    Unidade de Enfermedades Tiroideas e Metabólicas (UETeM), Complexo Hospitalario Universitary de Santiago (CHUS), University of Santiago de Compostela, Santiago de Compostela, 15705, Spain.

    Objective: Toxic thyroid adenoma (TA) is a common cause of hyperthyroidism. Mutations in the TSH receptor (TSHR) gene, and less frequently in the adenylate cyclase-stimulating G alpha protein (GNAS) gene, are well established causes of TA in Europe. However, genetic causes of TA remain unknown in a small percentage of cases. We report the first study to investigate mutations in TSHR, GNAS, protein kinase, cAMP-dependent, regulatory, type I alpha (PRKAR1A) and RAS genes, in a large series of TA from Galicia, an iodine-deficient region in NW Spain.

    Eighty-five TA samples were obtained surgically from 77 hyperthyroid patients, operated on for treatment of non-autoimmune toxic nodular goitre. After DNA extraction, all coding exons of TSHR, GNAS and PRKAR1A genes, and exons 2 and 3 of HRAS, KRAS and NRAS were amplified by PCR and sequenced. Previously unreported mutants were cloned in expression vectors and their basal constitutive activities were determined by quantification of cAMP response element (CRE)-luciferase activity in CO7 cells transfected with wild-type and mutant plasmids.

    Results: TSHR gene mutations were found in 52 (61.2%) samples, GNAS gene mutations in 4 (4.71%) samples and no PRKAR1A or RAS mutations were found. Only three previously unreported mutations were found, two affecting the TSHR, A623F and I635V, and one affecting the G-protein alpha-subunit (Gsalpha), L203P. All mutant proteins showed higher CRE-luciferase activity than their wild-type counterparts.

    Conclusions: TA in a hyperthyroid population living in Galicia, a Spanish iodine-deficient region, harbours elevated frequencies of TSHR and GNAS mutations activating the cAMP pathway. However, the genetic cause of TA was undetermined in 34% of the TA samples.

    European journal of endocrinology 2008;159;5;623-31

  • Prostacyclin receptor-induced STAT3 phosphorylation in human erythroleukemia cells is mediated via Galpha(s) and Galpha(16) hybrid signaling.

    Lo RK, Liu AM, Wise H and Wong YH

    Department of Biochemistry, Molecular Neuroscience Center, and Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.

    Human prostacyclin receptor (hIP) stimulates STAT3 via pertussis toxin-insensitive G proteins in human erythroleukemia (HEL) cells. Since hIP can utilize G(s) and G(q) proteins for signal transduction and that both G proteins can induce STAT3 phosphorylation and activation via complex signaling networks, we sought to determine if one of them is predominant in mediating the hIP signal. Stimulation of STAT3 Tyr(705) and Ser(727) phosphorylations by the IP-specific agonist, cicaprost, was sensitive to inhibition of protein kinase A, phospholipase Cbeta, protein kinase C, calmodulin-dependent protein kinase II and Janus kinase 2/3. Unlike Galpha(16)-mediated regulation of STAT3 in the same cells, cicaprost-induced STAT3 Tyr(705) phosphorylation was resistant to inhibition of Src and MEK while STAT3 Ser(727) phosphorylation distinctly required phosphatidylinositol-3 kinase. This unique inhibitor-sensitivity pattern of STAT3 phosphorylation was reproduced in HEL cells by stimulating the G(16)-coupled C5a receptor in the presence of dibutyryl-cAMP, suggesting that the change in inhibitor-sensitivity was due to activation of the G(s) pathway. This postulation was confirmed by expressing constitutively active Galpha(16)QL and Galpha(s)QL in human embryonic kidney 293 cells and the inhibitor-sensitivity of Galpha(16)QL-induced STAT3 phosphorylations could be converted by the mere presence of Galpha(s)QL to resemble that obtained with cicaprost in HEL cells. In addition, the restoration of the Galpha(16)-mediated inhibitor-sensitivity upon cicaprost induction in Galpha(s)-knocked down HEL cells again verified the pivotal role of G(s) signal. Taken together, our observations illustrate that co-stimulation of G(s) and G(q) can result in the fine-tuning of STAT3 activation status, and this may provide the basis for cell type-specific responses following activation of hIP.

    Cellular signalling 2008;20;11;2095-106

  • Cutaneous and superficial soft tissue lesions associated with Albright hereditary osteodystrophy: clinicopathological and molecular genetic study of 4 cases, including a novel mutation of the GNAS gene.

    Kacerovska D, Nemcova J, Pomahacova R, Michal M and Kazakov DV

    Sikl's Department of Pathology, Charles University, Medical Faculty Hospital, Pilsen, Czech Republic.

    Albright hereditary osteodystrophy is a rare syndrome, in which cutaneous and superficial soft tissue lesions traditionally include osteomas and calcifications. We report 4 patients from 2 families affected with Albright hereditary osteodystrophy and demonstrate that the spectrum of these cutaneous and soft tissue lesions is broader than is usually defined in the literature. In addition to osteomas in the dermis and subcutis, including so-called plaque-like osteoma, we identified the following lesions: calcifying aponeurotic fibroma-like lesion, calcinosis circumscripta-like lesion, and unusual nevi with osteoid and/or peculiar intranuclear pseudoinclusions. One osteoma and the calcifying aponeurotic fibroma-like lesion were analyzed by HUMARA and proved to be clonal. In a family, a novel mutation in the GNAS gene was also identified.

    The American Journal of dermatopathology 2008;30;5;417-24

  • [Heterotrimeric G protein].

    Urano D and Itoh H

    d-urano@bs.naist.jp

    Nihon yakurigaku zasshi. Folia pharmacologica Japonica 2008;132;2;121-3

  • Physiological dysfunctions associated with mutations of the imprinted Gnas locus.

    Krechowec S and Plagge A

    Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Liverpool, United Kingdom.

    The ubiquitous Galphas-subunit of the trimeric, stimulatory G-protein plays a central role in receptor-mediated signal transduction, coupling receptor activation with the production of cAMP. The Galphas-encoding locus Gnas is now known to consist of a complex arrangement of several protein-coding and noncoding transcripts. We provide an overview of its genomic organization, its regulation by genomic imprinting, and a summary of the physiological roles of the alternative protein variants Galphas and XLalphas as determined from deficient mouse models.

    Funded by: Medical Research Council: G0601256

    Physiology (Bethesda, Md.) 2008;23;221-9

  • Diagnostic and mutational spectrum of progressive osseous heteroplasia (POH) and other forms of GNAS-based heterotopic ossification.

    Adegbite NS, Xu M, Kaplan FS, Shore EM and Pignolo RJ

    Department of Orthopaedic Surgery, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania 19104, USA.

    Progressive osseous heteroplasia (POH) is a rare, disabling disease of heterotopic ossification (HO) that progresses from skin and subcutaneous tissues into deep skeletal muscle. POH occurs in the absence of multiple developmental features of Albright hereditary osteodystrophy (AHO) or hormone resistance, clinical manifestations that are also associated with GNAS inactivation. However, occasional patients with AHO and pseudohypoparathyroidism 1a/c (PHP1a/c; AHO features plus hormone resistance) have also been described who have progressive HO. This study was undertaken to define the diagnostic and mutational spectrum of POH and progressive disorders of HO, and to distinguish them from related disorders in which HO remains confined to the skin and subcutaneous tissues. We reviewed the charts of 111 individuals who had cutaneous and subcutaneous ossification. All patients were assessed for eight characteristics: age of onset of HO, presence and location of HO, depth of HO, type of HO, progression of HO, features of AHO, PTH resistance, and GNAS mutation analysis. We found, based on clinical criteria, that POH and progressive HO syndromes are at the severe end of a phenotypic spectrum of GNAS-inactivating conditions associated with extra-skeletal ossification. While most individuals with superficial or progressive ossification had mutations in GNAS, there were no specific genotype-phenotype correlations that distinguished the more progressive forms of HO (e.g., POH) from the non-progressive forms (osteoma cutis, AHO, and PHP1a/c).

    Funded by: NIAMS NIH HHS: R01 AR046831, R01 AR046831-07, R01-AR46831

    American journal of medical genetics. Part A 2008;146A;14;1788-96

  • Reviews in molecular biology and biotechnology: transmembrane signaling by G protein-coupled receptors.

    Luttrell LM

    Division of Endocrinology, Diabetes and Medical Genetics, Department of Medicine, Medical University of South Carolina, 96 Jonathan Lucas Street, 816 CSB, P.O. Box 250624, Charleston, SC 29425, USA. luttrell@musc.edu

    As the most diverse type of cell surface receptor, the importance heptahelical G protein-coupled receptors (GPCRs) to clinical medicine cannot be overestimated. Visual, olfactory and gustatory sensation, intermediary metabolism, cell growth and differentiation are all influenced by GPCR signals. The basic receptor-G protein-effector mechanism of GPCR signaling is tuned by a complex interplay of positive and negative regulatory events that amplify the effect of a hormone binding the receptor or that dampen cellular responsiveness. The association of heptahelical receptors with a variety of intracellular partners other than G proteins has led to the discovery of potential mechanisms of GPCR signaling that extend beyond the classical paradigms. While the physiologic relevance of many of these novel mechanisms of GPCR signaling remains to be established, their existence suggests that the mechanisms of GPCR signaling are even more diverse than previously imagined.

    Molecular biotechnology 2008;39;3;239-64

  • The GNAS1 T393C polymorphism and lack of clinical prognostic value in chronic lymphocytic leukemia.

    Kaderi MA, Murray F, Jansson M, Merup M, Karlsson K, Roos G, Aleskog A and Tobin G

    Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden.

    Chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease with no known single predisposing genetic factor shown in all cases. Recently, a single nucleotide polymorphism (SNP) T393C in the GNAS1 gene has been reported to have a clinical impact on CLL progression and overall survival. In order to further investigate the T393C SNP in CLL, we have genotyped 279 CLL cases and correlated the genotypes to clinical outcome and other known prognostic factors such as the immunoglobulin heavy chain variable (IGHV) gene mutation status and CD38 expression. In the present study, no difference in overall survival or time to treatment was observed in the CLL patients with the different genotypes in contrast to the previous report. Furthermore, no correlation was observed with the T393C genotypes and IGHV mutational status, Binet stage or CD38 in this cohort. In summary, our data does not support the use of the T393C GNAS SNP as a clinical prognostic factor in CLL.

    Leukemia research 2008;32;6;984-7

  • Androgens transduce the G alphas-mediated activation of protein kinase A in prostate cells.

    Bagchi G, Wu J, French J, Kim J, Moniri NH and Daaka Y

    Department of Pathology, Medical College of Georgia, Augusta, GA 30912, USA.

    Androgens regulate the development and function of male reproductive organs and play a crucial role in the onset and progression of prostate cancer. Androgen action is primarily mediated through the nuclear androgen receptor (AR) which acts as a ligand-dependent transcription factor. This mode of androgen action takes hours to manifest and is called the genomic pathway. The androgen-mediated genomic responses require activity of cyclic AMP (cAMP)-dependent protein kinase (PKA). Androgens also act through nongenomic pathways in certain cell types to evoke rapid responses (manifested in minutes) that are mediated through changes in ion currents and second messengers. Here, we show that androgen causes the rapid and cAMP-dependent activation of PKA in prostate cells. The androgen-induced PKA activation is not inhibited by nuclear AR antagonist bicalutamide and can be observed in cells that do not express nuclear AR gene. Reduction of G alphas expression with siRNA attenuates the androgen-mediated activation of PKA, which is required for the androgen-induced prostate cell proliferation. We conclude that androgen actively evokes a nongenomic signaling pathway to activate PKA that is needed for the genomic functioning of nuclear AR. The inhibition of PKA activation, together with standard AR-targeted therapies, may be more efficacious for treatment of patients with prostate cancer.

    Funded by: NIA NIH HHS: AG17952, R01 AG017952; NIDDK NIH HHS: DK60917, R01 DK060917

    Cancer research 2008;68;9;3225-31

  • Functional evidence for presence of lipid rafts in erythrocyte membranes: Gsalpha in rafts is essential for signal transduction.

    Kamata K, Manno S, Ozaki M and Takakuwa Y

    Department of Biochemistry, Tokyo Women's Medical University, Tokyo, Japan.

    Membrane microdomains enriched in cholesterol and sphingolipids and containing specific membrane proteins are designated as lipid rafts. Lipid rafts have been implicated in cell signaling pathways in various cell types. Heterotrimeric guanine nucleotide-binding protein (Gsalpha) has been shown to be a raft component of erythrocytes and has been implicated in cell signaling. Rafts are isolated as detergent-resistant microdomains (DRMs) for biochemical analysis. Cholesterol depletion is widely used to disrupt raft structures to study their function in biological membranes. In the present study, we developed an alternate strategy for disrupting raft structures without altering membrane cholesterol content. Lidocaine hydrochloride, an amphipathic local anesthetic, is shown to reversibly disrupt rafts in erythrocyte a41 membranes and alter the Gsalpha dependent signal transduction pathway. These findings provide evidence for the presence of rafts while maintaining normal cholesterol content in erythrocyte membranes and confirm a role for raft-associated Gsalpha in signal transduction in erythrocytes.

    American journal of hematology 2008;83;5;371-5

  • Meiotic arrest in human oocytes is maintained by a Gs signaling pathway.

    DiLuigi A, Weitzman VN, Pace MC, Siano LJ, Maier D and Mehlmann LM

    Department of Cell Biology and Center for Advanced Reproductive Services, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.

    In mammalian oocytes, the maintenance of meiotic prophase I arrest prior to the surge of LH that stimulates meiotic maturation depends on a high level of cAMP within the oocyte. In mouse and rat, the cAMP is generated in the oocyte, and this requires the activity of a constitutively active, Gs-linked receptor, GPR3 or GPR12, respectively. To examine if human oocyte meiotic arrest depends on a similar pathway, we used RT-PCR and Western blotting to look at whether human oocytes express the same components for maintaining arrest as rodent oocytes. RNA encoding GPR3, but not GPR12, was expressed. RNA encoding adenylate cyclase type 3, which is the major adenylate cyclase required for maintaining meiotic arrest in the mouse oocyte, was also expressed, as was Galphas protein. To determine if this pathway is functional in the human oocyte, we examined the effect of injecting a function-blocking antibody against Galphas on meiotic resumption. This antibody stimulated meiotic resumption of human oocytes that were maintained at the prophase I stage using a phosphodiesterase inhibitor. These results demonstrate that human oocytes maintain meiotic arrest prior to the LH surge using a signaling pathway similar to that of rodent oocytes.

    Funded by: NICHD NIH HHS: HD056366, R01 HD056366, R01 HD056366-01; NIDDK NIH HHS: DK073499, R01 DK073499, R01 DK073499-03

    Biology of reproduction 2008;78;4;667-72

  • Mutation T/C,Ile 131 of the gene encoding the alfa subunit of the human Gs protein and predisposition to vasovagal syncope.

    Lelonek M, Pietrucha T, Matyjaszczyk M and Goch JH

    Department of Cardiology, I Chair of Cardiology and Cardiac Surgery, Medical University of Lodz, Sterling Str. 1/3, 91-425 Lodz, Poland. mlelonek@poczta.fm

    Background: Mutation T/C inside codon 131 of the gene encoding the alpha subunit of Gs protein (GNAS1) causes the increased activation of adenyl cyclase, which plays an important role in cardiovascular regulation. The aim of the present study was to evaluate GNAS1 T/C,Ile 131 mutation's manifestation in syncopal patients regarding head-up tilt test (HUTT) results.

    In 137 syncopal patients (without any other diseases) the silent T/C,Ile 131 mutation within the GNAS1 codon on chromosome 20 q was identified. This mutation consists of the presence (+) or absence (-) of a target site for endonuclease FokI (Promega). Ninety-six patients (70%) with positive HUTT had a higher FokI+ allele frequency compared with those with negative tilting results (49% vs 27%, X(2)=12.05; p<0.001). In positive tilted patients, the studied mutation had significant influence on blood pressure (p<0.05). When comparing positive HUTT with vasodepressore component, cardioinhibition results and negative HUTT, the frequencies of the FokI+ allele were decreased among these groups: 53%, 36% and 27%, respectively.

    Conclusions: An association between positive tilting and mutation C/T,Ile 131 within the GNAS1 codon was found. The predisposition to vasovagal syncope seems to be associated with the GNAS1 FokI+ allele.

    Circulation journal : official journal of the Japanese Circulation Society 2008;72;4;558-62

  • Postmortem brain tissue of depressed suicides reveals increased Gs alpha localization in lipid raft domains where it is less likely to activate adenylyl cyclase.

    Donati RJ, Dwivedi Y, Roberts RC, Conley RR, Pandey GN and Rasenick MM

    Department of Physiology and , University of Illinois at Chicago, College of Medicine, Chicago, Illinois 60612-7342, USA.

    Recent in vivo and in vitro studies have demonstrated that Gs alpha migrates from a Triton X-100 (TX-100)-insoluble membrane domain (lipid raft) to a TX-100-soluble nonraft membrane domain in response to chronic, but not acute, treatment with tricyclic or selective serotonin reuptake inhibitor antidepressants. This migration resulted in a more facile association with adenylyl cyclase. Our hypothesis is that Gs alpha may be ensconced, to a greater extent, in lipid rafts during depression, and that one action of chronic antidepressant treatment is to reverse this. In this postmortem study, we examined Gs alpha membrane localization in the cerebellum and prefrontal cortex of brains from nonpsychiatric control subjects and suicide cases with confirmed unipolar depre f47 ssion. Sequential TX-100 and TX-114 detergent extractions were performed on the brain tissue. In the cerebellum, the ratio of TX-100/TX-114-soluble Gs alpha is approximately 2:1 for control versus depressed suicides. Results with prefrontal cortex samples from each group demonstrate a similar trend. These data suggest that depression localizes Gs alpha to a membrane domain (lipid rafts) where it is less likely to couple to adenylyl cyclase and that antidepressants may upregulate Gs alpha signaling via disruption of membrane microenvironments. Raft localization of Gs alpha in human peripheral tissue may thus serve as a biomarker for depression and as a harbinger of antidepressant responsiveness.

    Funded by: NIDA NIH HHS: DA020568; NIMH NIH HHS: MH 01836, MH 068777, MH 39595, MH 60744, R01 MH 48153, R01 MH60744

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2008;28;12;3042-50

  • Overall and relapse-free survival in oropharyngeal and hypopharyngeal squamous cell carcinoma are associated with genotypes of T393C polymorphism of the GNAS1 gene.

    Lehnerdt GF, Franz P, Zaqoul A, Schmitz KJ, Grehl S, Lang S, Schmid KW, Siffert W, Jahnke K and Frey UH

    Department of Otorhinolaryngology, West German Cancer Center Essen, Germany. goetz.lehnerdt@uni-due.de

    Purpose: In previous studies, we have shown that the T allele of a specific single-nucleotide polymorphism (SNP) in the Galphas gene (T393C) correlates with increased Galphas expression and hence apoptosis. The T allele was associated with a favorable outcome in a variety of human cancers, e.g., carcinoma of the urinary bladder, kidney, and colorectum.

    The prognostic value of the T393C SNP was evaluated in an unselected series of patients treated with curative intent for oropharyngeal and hypopharyngeal squamous cell carcinomas, including all tumor stages with different therapeutic regimens. Genotype analysis was done using DNA from paraffin-embedded tissue samples from 202 patients (162 men, 40 women) with a median follow-up of 38 months (1-133 months). The various genotypes were correlated with relapse-free and overall survival.

    Results: GNAS1 393C homozygous patients displayed a higher risk for disease progression than T393 homozygous patients (hazard ratio CC versus TT, 1.9; 95% confidence interval, 1.1-3.2; P = 0.019). The same genotype effect was observed for overall survival with CC genotypes at higher risk for death compared with TT genotypes (hazard ratio, 1.7; 95% confidence interval, 1.1-2.9; P = 0.015). Multivariate analysis showed that, besides American Joint Committee on Cancer stage, tumor localization, and gender, the T393C polymorphism was an independent prognostic factor for disease progression and death.

    Conclusion: The T393C SNP could be considered as a genetic marker to predict the clinical course of patients suffering from oropharyngeal and hypopharyngeal cancer.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2008;14;6;1753-8

  • A maternal epimutation of GNAS leads to Albright osteodystrophy and parathyroid hormone resistance.

    Mariot V, Maupetit-Méhouas S, Sinding C, Kottler ML and Linglart A

    Pediatric Endocrinology and Institut National de la Santé et de la Recherche Médicale U561, Hôpital St-Vincent de Paul, 82 avenue Denfert-Rochereau, 75014 Paris V University, France.

    Context: Pseudohypoparathyroidism (PHP) type Ia is a rare maternally transmitted disease due to maternal loss-of-function mutations of GNAS, the gene encoding Galphas, the alpha-stimulatory subunit of the G protein. Affected individuals display hormonal resistance (mainly PTH and TSH resistance) and Albright hereditary osteodystrophy. PHP type Ib (PHP-Ib), usually defined by isolated renal resistance to PTH and sometimes mild TSH resistance, is due to a maternal loss of GNAS exon A/B methylation, leading to decreased Galphas expression in specific tissues.

    We report a girl with obvious Albright osteodystrophy features, PTH resistance, normal Galphas bioactivity in red blood cells, yet no loss-of-function mutation in the GNAS coding sequence (exons 1-13). The methylation analysis of the four GNAS differentially methylated regions, i.e. NESP, AS, XL, and A/B, revealed broad methylation changes at all differentially methylated regions, including GNAS exon A/B, leading to a paternal epigenotype on both alleles.

    Conclusions: This observation suggests that: 1) the decreased expression of Galphas due to GNAS epimutations is not restricted to the renal tubule but may affect nonimprinted tissues like bone; 2) PHP-Ib is a heterogeneous disorder that should lead to studying GNAS epigenotype in patients with PHP and no mutation in GNAS exons 1-13, regardless of their physical features.

    The Journal of clinical endocrinology and metabolism 2008;93;3;661-5

  • Expression of pituitary tumour-derived, N-terminally truncated isoform of fibroblast growth factor receptor 4 (ptd-FGFR4) correlates with tumour invasiveness but not with G-protein alpha subunit (gsp) mutation in human GH-secreting pituitary adenomas.

    Morita K, Takano K, Yasufuku-Takano J, Yamada S, Teramoto A, Takei M, Osamura RY, Sano T and Fujita T

    Department of Nephrology and Endocrinology, University of Tokyo Faculty of Medicine, Tokyo, Japan. ktakano-tky@uminutesac.jp

    Objective: Apart from the constitutively activating mutation of the G-protein alpha subunit (Gsalpha) (gsp mutation), factors involved in tumorigenesis or those in tumour behavio 1f40 ur remain elusive in sporadic GH-secreting pituitary adenomas. Recently, the N-terminally truncated form of fibroblast growth factor receptor-4 (ptd-FGFR4) was identified in pituitary adenomas. This aberrant receptor has transforming activity, and causes pituitary adenomas in transgenic mice. The clinical relevance of this receptor warrants investigation. Our objective was twofold: first, to examine how the expression of ptd-FGFR4 relates to gsp mutations; and second, to see whether patients with this receptor have unique clinical characteristics.

    mRNA was extracted from excised adenomas of 45 Japanese acromegalic patients. ptd-FGFR4 expression and gsp mutations were determined by reverse transcription polymerase chain reaction (RT-PCR) and direct sequencing. Preoperative clinical data were collected by reviewing medical charts and pituitary magnetic resonance imaging (MRI) scans.

    Results: ptd-FGFR4 mRNA expression was detected in 19 out of 45 tumours (42.2%) while gsp mutations were detected in 25 out of 45 tumours (55.6%). The prevalence of ptd-FGFR4 expression did not differ between gsp-positive (44.0%) and gsp-negative (40.0%) tumours (P = 1.00). ptd-FGFR4-positive tumours invaded the cavernous sinus more frequently (P = 0.0098) than did the ptd-FGFR4-negative tumours. Tumour size was not statistically different between ptd-FGFR4-positive and -negative tumours (P = 0.198). The presence of ptd-FGFR4 did not correlate with age at operation, sex, preoperative serum GH or IGF-1 levels.

    Conclusions: We found that ptd-FGFR4 expression and gsp mutations occur independently of each other, and that ptd-FGFR4 expression is associated with more invasive tumours in patients with GH-secreting pituitary adenomas.

    Clinical endocrinology 2008;68;3;435-41

  • Premature thelarche from phenotype to genotype.

    Codner E and Román R

    Institute of Maternal and Child Research, (IDIMI), School of Medicine, University of Chile, Casilla 226-3, Santiago, Chile. ecodner@med.uchile.cl

    Premature thelarche is a benign condition, which has been described as a "variant of puberty". Early breast development is especially prevalent during the first year of life, when the gonadal axis is usually active. Ultrasensitive bioassays have described higher estrogen levels in these girls compared to controls. Some cases of premature thelarche may also exhibit increased growth velocity and/or bone age, despite prepubertal gonadotropin secretion. These cases have been labeled as exaggerated thelarche and may represent an intermediate state between benign premature thelarche and precocious puberty. Several factors have been associated with the etiology of premature thelarche, such as endocrine disruptors, and genetic and nutritional factors. Recently, it has been shown that some girls with exaggerated or fluctuating thelarche may have an activating mutation in the GNAS gene, which codifies for alpha subunit of G stimulating protein (Gsalpha). We discuss the different phenotypes that may be associated with PT and its etiology.

    Pediatric endocrinology reviews : PER 2008;5;3;760-5

  • The same mutation in Gsalpha and transducin alpha reveals behavioral differences between these highly homologous G protein alpha-subunits.

    Zurita AR and Birnbaumer L

    Laboratory of Neurobiology, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.

    Mutating Arg-238 to Glu (R238E) in the switch 3 region of a transducin alpha (*Talpha) in which 27 aa of the GTPase domain have been replaced with those of the alpha-subunit of the inhibitory G protein 1 (Gi1alpha), was reported to create an alpha-subunit that is resistant to activation by GTPgammaS, is devoid of resident nucleotide, and has dominant negative (DN) properties. In an attempt to create a DN stimultory G protein alpha (Gsalpha) with a single mutation we created Gsalpha-R265E, equivalent to *Talpha-R238E. Gsalpha-R265E has facilitated activation by GTPgammaS, a slightly facilitated activation by GTP but much reduced receptor plus GTP stimulated activation, and an apparently unaltered ability to interact with receptor as seen in ligand binding studies. Further, t ace he activity profile of Gsalpha-R265E is that of an alpha-subunit with unaltered or increased GTPase activity. The only change in Gsalpha that is similar to that in *Talpha is that the apparent affinity for guanine nucleotides is decreased in both proteins. The molecular basis of the changed properties are discussed based on the known crystal structure of Gsalpha and the changes introduced by the same mutation in a *Talpha (Gtalpha*) with only 23 aa from Gi1alpha. Gtalpha*-R238E, with four fewer mutations in switch 3, was reported to show no evidence of DN properties, is activated by GTPgammaS, and has reduced GTPase activity. The data highlight a critical role for the switch 3 region in setting overall properties of signal-transducing GTPases.

    Funded by: Intramural NIH HHS

    Proceedings of the National Academy of Sciences of the United States of America 2008;105;7;2363-8

  • A novel promoter polymorphism in the human gene GNAS affects binding of transcription factor upstream stimulatory factor 1, Galphas protein expression and body weight regulation.

    Frey UH, Hauner H, Jöckel KH, Manthey I, Brockmeyer N and Siffert W

    Institute of Pharmacogenetics, Department of Anesthesiology and Intensive Care Medicine, University Hospital, Essen, Germany.

    Objectives: Body weight regulation is under complex control involving the central nervous system and peripheral pathways. The beta-adrenoceptor Galphas protein system plays an important role in heart rate regulation and lipid mobilization suggesting a key role for the stimulatory G protein Galphas in body weight regulation.

    Methods: We sequenced the whole GNAS promoter to identify a functional variant which results in altered Galphas expression. We genotyped 110 participants of a randomized placebo-controlled weight loss trial who were under a low calorie diet and were additionally treated with either placebo or 15 mg sibutramine daily for 54 weeks and associated the respective alleles with regard to treatment outcome using an intention-to-treat analysis.

    Results: A G>A transition at position -1211 the human GNAS promoter (minor allele frequency=0.36) was identified resulting in altered upstream stimulatory factor 1 transcription factor binding, promoter activity, Galphas expression, and lipolysis. Under a low calorie diet -1211GG genotypes lost significantly more weight compared with A-allele carriers (placebo group: 1211GG, 7.5+/-0.4 versus -1211A, 4.5+/-0.3 kg, P=0.020). Sibutramine was effective only in A-allele carriers whereas GG genotypes showed no additional weight loss under sibutramine but showed the strongest increases in resting heart rate (8.5 bpm; 95% confidence interval: 2.7-14.21 bpm; P=0.005) and systolic blood pressure (9.1 mmHg, 95% confidence interval: 3.1-15.1; P=0.004) compared with placebo.

    Conclusions: Determination of GNAS promoter alleles may identify obese individuals who lose weight easily under lifestyle changes alone but also those who benefit from adjunct sibutramine therapy.

    Pharmacogenetics and genomics 2008;18;2;141-51

  • Stimulatory heterotrimeric GTP-binding protein inhibits hydrogen peroxide-induced apoptosis by repressing BAK induction in SH-SY5Y human neuroblastoma cells.

    Kim SY, Seo M, Kim Y, Lee YI, Oh JM, Cho EA, Kang JS and Juhnn YS

    Department of Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799.

    Heterotrimeric stimulatory GTP-binding protein (G(s)) stimulates adenylate cyclases to activate the cAMP signaling pathway. Although the cAMP pathway has been reported to be involved in apoptosis, the role of the G(s)-cAMP signaling pathway during reactive oxygen species (ROS)-mediated apoptosis, which is involved in the resistance of cancer cells to chemotherapy and radiation, is not clearly understood. Thus, in this study we aimed to investigate the role of the alpha subunit of G(s) (Galpha(s)) in the ROS-induced apoptosis of cancer cells. The stable expression of constitutively active Galpha(s) (Galpha(s)QL) inhibited the hydrogen peroxide-induced apoptosis of SH-SY5Y human neuroblastoma cells and reduced the hydrogen peroxide-induced increase in Bak and the decrease in Bcl-x(L) protein expression. Exogenous Bak expression abolished these inhibitory effects of Galpha(s)QL, but Bak small interfering RNA decreased hydrogen peroxide-induced apoptosis. Galpha(s) repressed hydrogen peroxide-induced Bak expression by inhibiting the transcription of Bak mRNA, which resulted from the inhibition of the hydrogen peroxide-induced activation of transcription factors such as AP1, NF-kappaB, and NFAT. Moreover, Galpha(s) also inhibited the hydrogen peroxide-induced binding of AP1, NF-kappaB, and NFAT to the Bak promoter. Furthermore, hydrogen peroxide-induced apoptosis was reduced by treating cells with prostaglandin E(2), which activates Galpha(s), but this was augmented by CCPA, which activates Galpha(i) causing a decrease in cAMP levels. From the results, we conclude that Galpha(s) protects neuroblastoma cells from hydrogen peroxide-induced apoptosis by repressing Bak induction, which is mediated by the inhibition of the hydrogen peroxide-induced activations of AP1, NF-kappaB, and NFAT through cAMP-PKA-CREB signaling system.

    The Journal of biological chemistry 2008;283;3;1350-61

  • Absence of GNAS and EGFL6 mutations in common human cancers.

    Lee SH, Jeong EG, Soung YH, Lee JW, Yoo NJ and Lee SH

    Pathology 2008;40;1;95-7

  • Elevation of growth hormone-releasing hormone receptor messenger ribonucleic acid expression in growth hormone-secreting pituitary adenoma with Gsalpha protein mutation.

    Sakai N, Kim K, Sanno N, Yoshida D, Teramoto A and Shibasaki T

    Department of Neurosurgery, Nippon Medical School, Tokyo, Japan.

    Growth hormone-releasing hormone (GHRH) stimulates not only the synthesis and secretion of GH but also the proliferation of normal somatotrophs. The expression of GHRH receptor (GHRHR) is regulated by GHRH, both of which are known to be expressed in human GH-secreting pituitary adenoma cells. Somatic mutations in the subunit of Gsalpha protein (gsp), lead to the constitutive activation of adenylyl cyclase in pituitary adenomas that secrete GH. It has not been examined how gsp mutations influence GHRHR expression in GH-secreting adenomas. We therefore analyzed the expression levels of GHRHR messenger ribonucleic acid (mRNA) in GH-secreting pituitary adenomas focusing on a gsp mutation. Furthermore, we investigated the effect of GHRH on the expression of GHRHR mRNA in primary cultures of GH-secreting pituitary adenoma cells. GHRHR mRNA expression levels were significantly elevated in gsp mutation-positive GH-secreting adenomas compared with those in gsp mutation-negative ones. In primary-cultured GH-secreting adenoma cells, the increase of GH secretion in response to GHRH was shown in both gsp mutation-positive and -negative adenoma cells with a significantly higher response in the latter adenoma cells. GHRH increased GHRHR mRNA expression level in gsp mutation-negative adenoma cells while it was not influenced by GHRH in gsp mutation-positive adenoma cells. These results suggest that gsp mutations up-regulate GHRHR mRNA expression in GH-secreting pituitary adenoma cells, and that gsp mutations desensitize the adenoma cells to GHRH in terms of their GHRHR mRNA expression probably because of their saturation of GHRH signaling.

    Neurologia medico-chirurgica 2008;48;11;481-7; discussion 487-8

  • Human G(salpha) mutant causes pseudohypoparathyroidism type Ia/neonatal diarrhea, a potential cell-specific role of the palmitoylation cycle.

    Makita N, Sato J, Rondard P, Fukamachi H, Yuasa Y, Aldred MA, Hashimoto M, Fujita T and Iiri T

    Department of Endocrinology and Nephrology, University of Tokyo School of Medicine, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.

    Pseudohypoparathyroidism type Ia (PHP-Ia) results from the loss of one allele of G(salpha), causing resistance to parathyroid hormone and other hormones that transduce signals via G(s). Most G(salpha)mutations cause the complete loss of protein expression, but some cause loss of function only, and these have provided valuable insights into the normal function of G proteins. Here we have analyzed a mutant G(salpha) (alphas-AVDT) harboring AVDT amino acid repeats within its GDP/GTP binding site, which was identified in unique patients with PHP-Ia accompanied by neonatal diarrhea. Biochemical and intact cell analyses showed that alphas-AVDT is unstable but constitutively active as a result of rapid GDP release and reduced GTP hydrolysis. This instability underlies the PHP-Ia phenotype. alphas-AVDT is predominantly localized in the cytosol, but in rat and mouse small intestine epithelial cells (IEC-6 and DIF-12 cells) alphas-AVDT was found to be localized predominantly in the membrane where adenylyl cyclase is present and constitutive increases in cAMP accumulation occur in parallel. The likely cause of this membrane localization is the inhibition of an activation-dependent decrease in alphas palmitoylation. Upon the overexpression of acyl-protein thioesterase 1, however, alphas-AVDT translocates from the membrane to the cytosol, and the constitutive accumulation of cAMP becomes attenuated. These results suggest that PHP-Ia results from the instability of alphas-AVDT and that the accompanying neonatal diarrhea may result from its enhanced constitutive activity in the intestine. Hence, palmitoylation may control the activity and localization of G(salpha) in a cell-specific manner.

    Proceedings of the National Academy of Sciences of the United States of America 2007;104;44;17424-9

  • Patients with mutations in Gsalpha have reduced activation of a downstream target in epithelial tissues due to haploinsufficiency.

    Hsu SC, Groman JD, Merlo CA, Naughton K, Zeitlin PL, Germain-Lee EL, Boyle MP and Cutting GR

    Department of Pediatric Endocrinology , Johns Hopkins University, 733 North Broadway, Suite 551, Baltimore, Maryland 21205, USA. shsu8@jhmi.edu

    Context: Patients with Albright hereditary osteodystrophy (AHO) have defects in stimulatory G protein signaling due to loss of function mutations in GNAS. The mechanism by which these mutations lead to the AHO phenotype has been difficult to establish due to the inaccessibility of the affected tissues.

    Objective: The objective of the study was to gain insight into the downstream consequences of abnormal stimulatory G protein signaling in human epithelial tissues.

    We assessed transcription of GNAS and Gsalpha-stimulated activation of the cystic fibrosis transmembrane conductance regulator (CFTR) in AHO patients, compared with normal controls and patients with cystic fibrosis.

    Relative expression of Gsalpha transcripts from each parental GNAS allele and cAMP measurements from nasal epithelial cells were compared among normal controls and AHO patients. In vivo measurements of CFTR function, pulmonary function, and pancreatic function were assessed in AHO patients.

    Results: GNAS was expressed equally from each allele in normals and two of five AHO patients. cAMP generation was significantly reduced in nasal respiratory epithelial cells from AHO patients, compared with normal controls (0.4 vs. 0.6, P = 0.0008). Activation of CFTR in vivo in nasal (P = 0.0065) and sweat gland epithelia (P = 0.01) of AHO patients was significantly reduced from normal. In three patients, the reduction in activity was comparable with patients with cystic fibrosis due to mutations in CFTR. Yet no AHO patients had pulmonary or pancreatic disease consistent with cystic fibrosis.

    Conclusions: In humans, haploinsufficiency of GNAS causes a significant reduction in the activation of the downstream target, CFTR, in vivo.

    Funded by: NHLBI NIH HHS: R01 HL68927; NICHD NIH HHS: K12 HD27799; NIDDK NIH HHS: F32 DK067748, R37 DK 44003, T32 DK007751

    The Journal of clinical endocrinology and metabolism 2007;92;10;3941-8

  • Gs alpha overexpression and loss of Gs alpha imprinting in human somatotroph adenomas: association with tumor size and response to pharmacologic treatment.

    Picard C, Silvy M, Gerard C, Buffat C, Lavaque E, Figarella-Branger D, Dufour H, Gabert J, Beckers A, Brue T, Enjalbert A and Barlier A

    Laboratory Interactions Cellulaires Neuroendocriniennes, UMR 6544 CNRS, Institut Fédératif Jean Roche, Faculté de Médecine Nord, Université de la Méditerranée, Marseille, France.

    Gs alpha, the alpha-subunit of the heterotrimeric GTP-binding protein, is coded from the GNAS gene, which is imprinted in a tissue-specific manner. Gs alpha is paternally silenced in normal pituitary, but Gs alpha imprinting relaxation is found in some tumoral tissue. In addition, Gs alpha mRNA levels are high in some somatotroph adenomas not bearing the active Gs alpha mutant, the gsp oncogene. In this study, the impact of loss of imprinting on Gs alpha expression level and on tumoral phenotype has been investigated. We compared the expression and imprinting of 4 transcripts of GNAS locus (NESP55, XL alpha s, exon 1A, Gs alpha) of 60 somatotroph adenomas with those of 23 lactotroph adenomas. The paternal and maternal transcripts were quantified using allele-specific real-time PCR and FokI polymorphism. Moreover, the methylation of exon 1A DMR was analyzed. As is the case for the gsp oncogene, high Gs alpha expression in gsp- tumors was associated with smaller tumor size and better octreotide sensitivity. A strong imprinting relaxation (percentage of paternal Gs alpha expressi 119e on >or=7.5%) was found only in gsp- tumors. The loss of Gs alpha imprinting was associated with a decrease in exon 1A mRNA expression. Unexpectedly, the methylation status of exon 1A DMR was not modified in relaxed tumors. Maternal Gs alpha mRNA level decreased with exon 1A level, and consequently the loss of Gs alpha imprinting did not induce the expected Gs alpha overexpression. Finally, XL alpha s mRNA level correlated with that of paternal Gs alpha and of NESP55 showing the complexity of gene regulation in the GNAS locus.

    International journal of cancer 2007;121;6;1245-52

  • The GNAS Locus: Quintessential Complex Gene Encoding Gsalpha, XLalphas, and other Imprinted Transcripts.

    Bastepe M

    Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.

    The currently estimated number of genes in the human genome is much smaller than previously predicted. As an explanation for this disparity, most individual genes have multiple transcriptional units that represent a variety of biologically important gene products. GNAS exemplifies a gene of such complexity. One of its products is the alpha-subunit of the stimulatory heterotrimeric G protein (Gsalpha), a ubiquitous signaling protein essential for numerous different cellular responses. Loss-of-function and gain-of-function mutations within Gsalpha-coding GNAS exons are found in various human disorders, including Albright's hereditary osteodystrophy, pseudohypoparathyroidism, fibrous dysplasia of bone, and some tumors of different origin. While Gsalpha expression in most tissues is biallelic, paternal Gsalpha expression is silenced in a small number of tissues, playing an important role in the development of phenotypes associated with GNAS mutations. Additional products derived exclusively from the paternal GNAS allele include XLalphas, a protein partially identical to Gsalpha, and two non-coding RNA molecules, the A/B transcript and the antisense transcript. The maternal GNAS allele leads to NESP55, a chromogranin-like neuroendocrine secretory protein. In vivo animal models have demonstrated the importance of each of the exclusively imprinted GNAS products in normal mammalian physiology. However, although one or more of these products are also disrupted by most naturally occurring GNAS mutations, their roles in disease pathogenesis remain unknown. To further our understanding of the significance of this gene in physiology and pathophysiology, it will be important to elucidate the cellular roles and the mechanisms regulating the expression of each GNAS product.

    Current genomics 2007;8;6;398-414

  • Genetic analysis and evaluation of resistance to thyrotropin and growth hormone-releasing hormone in pseudohypoparathyroidism type Ib.

    Mantovani G, Bondioni S, Linglart A, Maghnie M, Cisternino M, Corbetta S, Lania AG, Beck-Peccoz P and Spada A

    Department of Medical Sciences, Endocrine Unit, Fondazione Policlinico Instituto di Ricovero e Cura a Carattere Scientifico, University of Milan, 20122 Milan, Italy. giovanna.mantovani@unimi.it

    Context: Pseudohypoparathyroidism (PHP) types Ia and Ib, are caused by mutations in GNAS exons 1-13 and GNAS methylation defects, respectively. PHP-Ia patients show Albright hereditary osteodystrophy (AHO) and resistance toward PTH and additional hormones, whereas PHP-Ib patients do not have AHO and hormone resistance is limited to PTH and, as reported in one paper, TSH. No study addressed the question of GH deficiency in PHP-Ib patients.

    Objectives: The objective of the study was to screen patients with clinically diagnosed PHP-Ib for genetic defects and investigate the presence of resistance to TSH and GHRH.

    We investigated GNAS differential methylation and STX16 microdeletions in genomic DNA from 10 patients with clinical diagnosis of sporadic PHP-Ib, i.e. PTH resistance without AHO. Resistance to GHRH was assessed by GH response to GHRH plus arginine. Thyroid function and ultrasonography were also evaluated.

    Results: Molecular analysis showed GNAS cluster imprinting defects in all PHP-Ib patients and the first de novo STX16 deletion in one apparently sporadic patient. Subclinical or clinical hypothyroidism due to resistance to TSH was present in nine of 10 patients, whereas a preserved GH response to a GHRH plus arginine test was present in all patients, with one exception.

    Conclusions: We report the first molecular analysis of Italian patients with PHP-Ib. Clinical investigation shows that, like PHP-Ia patients, PHP-Ib patients are resistant to TSH, whereas they maintain a normal responsiveness to GHRH, at variance with PHP-Ia patients. These data provide new information on this rare disease and emphasize the clinical heterogeneity of genetic defects within GNAS.

    The Journal of clinical endocrinology and metabolism 2007;92;9;3738-42

  • GNAS transcripts in skeletal progenitors: evidence for random asymmetric allelic expression of Gs alpha.

    Michienzi S, Cherman N, Holmbeck K, Funari A, Collins MT, Bianco P, Robey PG and Riminucci M

    Fondazione Parco Scientifico San Raffaele, Rome, Italy.

    Activating mutations of the Gsalpha gene, encoded by the guanine nucleotide-binding protein, alpha stimulating (GNAS) locus located on chromosome 20q13, underlie different clinical phenotypes characterized by skeletal lesions [fibrous dysplasia (FD) of bone], extraskeletal diseases (mainly endocrine hyperfunction and skin hyperpigmentation) and variable combinations thereof [the McCune-Albright syndrome (MAS)]. This clinical heterogeneity is commonly assumed to reflect the post-zygotic origin of the mutation. However, the pattern of imprinting of the Gsalpha gene in some human post-natal tissues suggests that parental-dependent epigenetic mechanisms may also play a role in the phenotypic effect of the mutated GNAS genotype. FD lesions are generated by mutated clonogenic osteoprogenitors that reside, along with their normal counterparts, in FD bone marrow stroma. We analyzed the allelic expression pattern of Gsalpha and other GNAS alternative transcripts in the progeny of normal and mutated clonogenic stromal cells isolated in vitro from a series of informative FD/MAS patients. We report here for the first time that the two Gsalpha alleles are unequally expressed in both normal and FD-mutated stromal clones. However, in contrast to imprinting, the ratio of Gsalpha allelic expression is randomly established in different clones from the same patient. This result suggests that a parental-independent modulation of Gsalpha expression occurs in clonogenic osteoprogenitor cells and, at the single cell level, may impact on the severity of an FD lesion. Furthermore, we show that normal and mutated clonogenic stromal cells express GNAS alternative transcripts other than the common Gsalpha, some of which may be relevant to the development of FD.

    Funded by: Telethon: GGP04263

    Human molecular genetics 2007;16;16;1921-30

  • Genetic and molecular aspects of McCune-Albright syndrome.

    SA, Schwindinger WF and Levine MA

    Department of Orthopaedic Surgery, Cleveland Clinic Lerner Research Institute, ND20, 9500 Euclid Avenue, Cleveland, Ohio 44195, USA.

    McCune-Albright syndrome (MAS) is characterized by the clinical triad of polyostotic fibrous dysplasia, café-au-lait pigmented skin lesions and endocrinopathy (1,2) The molecular lesion in MAS is a postzygotic mutation in the GNAS gene that leads to activation of Gsalpha, the alpha chain of the heterotrimeric G protein, Gsalpha. Cells that carry the activating mutation are distributed in a mosaic pattern. A clinical diagnosis of MAS can be made when a patient is found to have at least two features of the classical triad (3). Because of the restricted pattern of distribution of the GNAS mutation, termed gsp, initial molecular analyses were limited to lesional tissue, but recent techniques such as peptide nucleic acid clamping have improved the sensitivity of current assays and now enable the detection of gsp mutations in circulating cells from many patients with MAS.

    Pediatric endocrinology reviews : PER 2007;4 Suppl 4;380-5

  • GNAS mutation detection is related to disease severity in girls with McCune-Albright syndrome and precocious puberty.

    Wagoner HA, Steinmetz R, Bethin KE, Eugster EA, Pescovitz OH and Hannon TS

    Department of Pediatrics, Division of Endocrinology, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh PA 15213-2524, USA.

    Background: McCune-Albright syndrome (MAS) is characterized by a triad of gonadotropin-independent precocious puberty, café au lait skin pigmentation and fibrous dysplasia of bone. MAS is due to activating mutations of GNAS, the gene encoding Gsalpha. Interest exists in the use of GNAS mutation analysis to make a definitive diagnosis when the phenotype is not diagnostic, i.e. in partial forms of MAS. The utility of using peripheral blood for mutation analysis in this setting has not been thoroughly evaluated.

    Objective: We performed a systematic analysis of genomic DNA for the detection of GNAS activating mutations in girls with MAS who presented with precocious puberty to evaluate whether identification of an activating mutation in peripheral blood is related to the presence of other features of MAS.

    Genomic DNA was isolated from blood from 13 girls with gonadotropin-i 1f40 ndependent precocious puberty. A polymerase chain reaction (PCR)-based technique was performed for GNAS mutation identification.

    Results: GNAS activating mutations were identified in 4 patients, all of whom had classic MAS based on clinical evidence.

    Conclusions: Detection of activating mutations in leukocyte genomic DNA extracted from peripheral blood samples from girls with gonadotropin-independent precocious puberty was associated with the presence of other phenotypic manifestations of MAS. Until improvements in the diagnostic utility of GNAS activating mutation analysis from leukocyte genomic DNA occur, such testing in patients with atypical forms of MAS should continue to be reserved for research settings.

    Funded by: NCRR NIH HHS: K23 RR17250-01

    Pediatric endocrinology reviews : PER 2007;4 Suppl 4;395-400

  • McCune-Albright syndrome and disorders due to activating mutations of GNAS1.

    Diaz A, Danon M and Crawford J

    Division of Pediatric Endocrinology, Weill Medical College of Cornell University, New York, NY, USA.

    It has been more than seven decades since Drs. Fuller Albright and Donovan McCune published the first reports on individuals with McCune-Albright syndrome (MAS). Since then, the classic triad of precocious puberty, café-aulait spots, and polyostotic bone dysplasia continues to define the syndrome. However, having gathered a better picture of the pathophysiology of MAS, the way this condition is understood has changed. Isolated activating mutations of the alpha subunit of the G protein (GNAS1) have been found in different tissues, including pituitary adenomas, thyroid adenomas, ovarian cysts, monostotic bone dysplasia, and the adrenal glands, to name a few. For this reason, we have added 'and disorders due to activating mutations of GNAS1' to the title of this review. We discuss here the clinical consequences of GNAS1 activating mutations in different body systems and organs, the diagnostic approach to MAS, and the current therapeutic recommendations.

    Journal of pediatric endocrinology & metabolism : JPEM 2007;20;8;853-80

  • Sudden infant death syndrome and activating GNAS1 gene mutations.

    Román R, López P, Johnson MC, Boric MA, Gallo M, Ponce C, Vargas S, Codner E and Cassorla F

    Institute of Maternal and Child Research, San Borja Arriarán Clinical Hospital, School of Medicine, University of Chile, Santiago, Chile.

    GNAS1 gene mutations cause the McCune-Albright syndrome. Some patients may develop unusual, severe, nonendocrine manifestations that may lead to death. We postulate that some cases of sudden infant death syndrome (SIDS) might be caused by GNAS1 gene mutations affecting vital organs. We studied two GNAS1 gene mutations (R201H and R201C) by allele specific PCR and enzymatic digestion in pulmonary, pancreas, liver, kidney, and heart tissue from 29 infants who suffered SIDS. The infants died at age 96 +/- 78 days. At the time of death, children had a height Z score of -0,04 +/- 0,95, a weight Z score of 0,04 +/- 0,91, and a weight for length Z score of 0,1 +/- 0,83. The molecular study by both techniques did not reveal any GNAS1 mutations in the tissues examined. We conclude that GNAS1 gene mutations do not appear to be present in tissues of infants with SIDS.

    Fetal and pediatric pathology 2007;26;4;199-205

  • GNAS1 T393C polymorphism is associated with migraine.

    Oterino A, Ruiz-Alegría C, Castillo J, Valle N, Bravo Y, Cayón A, Alonso A, Tejera P, Ruiz-Lavilla N, Muñoz P and Pascual J

    Service of Neurology, University Hospital Marqués de Valdecilla (UC), Santander, Spain. aoterino@humv.es

    Migraineurs have an interictal sympathetic nervous system (SNS) hypofunctionality and hypersensitivity to adrenergic amines. The GNAS1 T393C polymorphism has been associated with a distinct SNS sensitivity in healthy subjects. We tested GNAS1 T393C variant in two independent sets of subjects. In the case-control subset, 365 migraine patients [194 with aura (MA)] vs. 347 healthy controls were studied. A significant excess of the CC genotype was found in migraneurs (31.2%) as opposed to controls (20.2%; P=0.003). Using a logistic regression model corrected for sex, the CC genotype conferred a general risk for migraine twice [odds ratio (OR) 1.79, 95% confidence interval (CI) 1.27-2.53; P=0.001] higher than CT/TT genotypes. Using parents from 117 migraine families, a marginally significant trend for association could be observed (P=0.025), but the transmission disequilibrium test for alleles maternally transmitted failed to demonstrate familial association. In this subgroup, CC genotype conferred a risk for migraine over twice (OR 2.20; 95% CI 1.14-4.40; P=0.019) higher than TT/TC genotypes. In conclusion, the GNAS1 T393C variant is associated with migraine, which suggests a genetic basis for its higher SNS sensitivity.

    Cephalalgia : an international journal of headache 2007;27;5;429-34

  • A case of McCune-Albright syndrome with associated multiple endocrinopathies.

    Sung SH, Yoon HD, Shon HS, HT, Choi WY, Seo CJ and Lee JH

    Department of Internal Medicine, Catholic University of Daegu School of Medicine, Daegu, Korea.

    McCune-Albright syndrome (MAS) is a rare disorder that develops from an activating mutation in the Gs gene. It is characterized by an association with Polyostotic fibrous dysplasia, and precocious puberty, Caf-au-lait pigmentation, and other endocrinopathies that result from the hyperactivity of a variety of endocrine glands. Recently we encountered a patient with MAS with fibrous dysplasia, skin pigmentation, acromegaly, hyperprolactinemia and a thyroid nodule. A 23-year-old male presented for an evaluation of a change in his facial structures. Fibrous dysplasia was diagnosed by a bone biopsy and radiographic studies. The GH level increased paradoxically after an oral glucose load. The plasma prolactin, IGF-1 and alkaline phosphatase were high. Thyroid ultrasonography revealed multiple nodules. The brain MRI demonstrated a mass in the left pituitary gland. Genetic analysis identified a change from Arg (CGT) at codon 201 to Cys (TGT).

    The Korean journal of internal medicine 2007;22;1;45-50

  • Body mass index differences in pseudohypoparathyroidism type 1a versus pseudopseudohypoparathyroidism may implicate paternal imprinting of Galpha(s) in the development of human obesity.

    Long DN, McGuire S, Levine MA, Weinstein LS and Germain-Lee EL

    Division of Pediatric Endocrinology, Department of Pediatrics, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, Maryland 21287, USA.

    Context: Obesity is a prominent feature of Albright hereditary osteodystrophy (AHO), a disorder caused by heterozygous GNAS mutations that disrupt the stimulatory G protein alpha-subunit Galpha(s). Because Galpha(s) is paternally imprinted in certain hormone target tissues, maternal inheritance of AHO leads to multihormone resistance [pseudohypoparathyroidism type 1a (PHP1a)], whereas paternal inheritance leads to AHO alone [pseudopseudohypoparathyroidism (pseudoPHP)]. Classically, the obesity in AHO is described as occurring similarly in both conditions.

    Setting: This observational study was conducted at the General Clinical Research Center, Johns Hopkins University School of Medicine; National Institutes of Health.

    Patients: Fifty-three patients with AHO (40 with PHP1a and 13 with pseudoPHP) and two with progressive osseous heteroplasia were studied.

    Main outcome measures were weight and height sd score (SDS), body mass index (BMI) percentiles, and BMI z-scores.

    Results: Patients with PHP1a had significantly greater mean weig b10 ht SDS, BMI percentages, and BMI z-scores compared with patients with pseudoPHP. These differences in BMI were secondary to adipose content based on dual energy x-ray absorptiometry analysis. The mean BMI z-score +/- sem for PHP1a was 2.31 +/- 0.18 compared with 0.65 +/- 0.31 in pseudoPHP (P = 0.000032). Twenty-five of 40 (62.5%) patients with PHP1a had mean BMI z-scores greater than two SDS above the mean, whereas no patients with pseudoPHP had BMI z-scores in this range.

    Conclusions: Although the AHO phenotype for PHP1a and pseudoPHP has been thought to be similar, we have found that obesity is a more prominent feature in PHP1a than in pseudoPHP and that severe obesity is characteristic of PHP1a specifically. These findings may implicate paternal imprinting of Galpha(s) in the development of human obesity.

    Funded by: Intramural NIH HHS: ZIA DK043302-16; NCRR NIH HHS: M01 RR00052; NIDDK NIH HHS: T32 DK007751

    The Journal of clinical endocrinology and metabolism 2007;92;3;1073-9

  • GNAS1 T393C polymorphism is associated with clinical course in patients with intrahepatic cholangiocarcinoma.

    Schmitz KJ, Lang H, Frey UH, Sotiropoulos GC, Wohlschlaeger J, Reis H, Takeda A, Siffert W, Schmid KW and Baba HA

    Institute of Pathology and Neuropathology, University of Duisburg-Essen, Essen, Germany.

    The GNAS1 locus encodes the Galphas protein, which stimulates the formation of cyclo-adenosinemonophosphate (cAMP). The cAMP pathway mediates pleiotropic effects, including the regulation of apoptosis and proliferation. We have recently shown that TT genotypes of the single-nucleotide polymorphism T393C in the gene GNAS1 predict the clinical outcome of patients with various carcinomas.

    Methods: Eighty-seven patients with intrahepatic cholangiocarcinoma (ICC) were retrospectively genotyped to elucidate a potential association between T393C genotypes and clinical outcome.

    Results: ICCs of patients with homozygous TT genotypes revealed a higher proliferation rate and a lower apoptotic rate. Homozygous TT patients were at highest risk for cancer-related deaths (hazard ratio = 2.74; 95% confidence interval = 1.03-7.28) compared with C-allele carriers. Kaplan-Meier curves for disease-specific overall and local recurrence-free survival in a subgroup with R(0)-resected ICC showed a significant association of T393 homozygosity with outcome, which was confirmed in multivariate Cox regression analysis.

    Conclusions: GNAS1 T393C is a novel independent host factor for disease progression in patients with ICC. Our finding that TT homozygosity (and not CC homozygosity) was associated with unfavorable clinical outcome points to the complex and differing functional effects induced by GNAS1 T393C polymorphism in various human carcinomas.

    Neoplasia (New York, N.Y.) 2007;9;2;159-65

  • Role of the intracellular domains of the human FSH receptor in G(alphaS) protein coupling and receptor expression.

    Ulloa-Aguirre A, Uribe A, Zariñán T, Bustos-Jaimes I and Pérez-Solis MA

    Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia Luis Castelazo Ayala, Instituto Mexicano del Seguro Social, Apartado Postal 99-065, Unidad Independencia, México 10101 D.F., Mexico. aulloaa@servidor.unam.mx

    The human (h) follicle-stimulating hormone receptor (FSHR) belongs to the superfamily of G protein-coupled receptors (GPCRs). This receptor consists of 695 amino acid residues and is preferentially coupled to the G(s) protein. This receptor is highly conserved among species (overall homology, 85%), with a 25-69% homology drop when compared to the human LH and TSH receptors. Although studies in prototypical rhodopsin/beta-adrenergic receptors suggest that multiple domains in the intracellular loops (iL) and the carboxyl-terminus (Ctail) of these receptors contribute to G protein coupling and receptor expression, there is a paucity of structure/function data on the role of these domains in FSHR function. Employing point mutations we have found that several residues present in the iL2 of the hFSHR are important for both coupling the receptor to the G(s) protein and maintaining the receptor molecule in an inactive conformation. In fact, HEK-293 cells expressing several hFSHR mutants with substitutions at R(450) (central to the highly conserved ERW triplet motif) and T(453) (a potential target for phosphorylation) failed to mediate ligand-provoked G(s) protein activation but not agonist binding, whereas substitutions at the hydrophobic L(460) (a conserved residue present in all glycoprotein hormone receptors) conferred elevated basal cAMP to the transfected cells. Thus, this particular loop apparently acts as a conformational switch for allowing the receptor to adopt an active conformation upon agonist stimulation. Residues in both ends of the iL3 are important for signal transduction in a number of GPCRs, including the FSHR. We have recently explored the importance of the reversed BBXXB motif (BXXBB; where B represents a basic residue and X a non-basic residue) present in the juxtamembrane region of the hFSHR iL3. A hFSHR mutant with all basic amino acids present in the iL3 BXXBB motif replaced by alanine failed to bind agonist and activate effector, and was expressed as an immature < or =62kDa form of the receptor. Individual substitutions of basic residues resulted in mutants that bound agonist normally but failed to activate effector when replaced at R(552) or R(556). Triple mutations in the same motif located in the NH(2)-end of the Ctail resulted in a complete inability of the receptor to bind agonist and activate effector, whereas individual substitutions resulted in decreased or virtually abolished agonist binding and cAMP accumulation, with both functions correlating with the detected levels of mature (80kDa) forms of the receptor. Thus, the BXXBB motif at the iL3 of the FSHR is essential for coupling the activated receptor to the G(s) protein, whereas the same motif in the Ctail is apparently more important for membrane expression. The role of cysteine residues present in the Ctail of the FSHR is an enigma since there are no conserved cysteines amongst LHR, FSHR and TSHR. C(629) and C(655) are conserved in the gonadotropin receptors but not in the TSHR. Alanine replacement of C(627) had no effect on hFSHR expression and function, whereas the same mutation at C(629) altered membrane expression and signal transduction. Serine or threonine substitutions of C(655) did not modify any of the parameters analyzed. In the hFSHR, C(629) may be a target for palmitoylation, and apparently it is the only cysteine residue in the Ctail domain that might play an important role in receptor function.

    Funded by: NICHD NIH HHS: HD18407, R01 HD018407

    Molecular and cellular endocrinology 2007;260-262;153-62

  • Analysis of GNAS mutations in 60 growth hormone secreting pituitary tumors: correlation with clinical and pathological characteristics and surgical outcome based on highly sensitive GH and IGF-I criteria for remission.

    Freda PU, Chung WK, Matsuoka N, Walsh JE, Kanibir MN, Kleinman G, Wang Y, Bruce JN and Post KD

    Department of Medicine, Columbia University College of Physicians & Surgeons, 650 West 168th Street, 9-905, New York, NY, USA. puf1@columbia.edu

    Although the molecular mechanisms underlying GH secreting pituitary tumor formation are not well understood, mutations in the alpha-subunit of the stimulatory G gene, GNAS, have been identified in up to 40%. As these mutations could play a role in tumor growth, we screened 60 GH secreting tumors for GNAS mutations and assessed whether mutation status correlated with their clinical and pathological characteristics. Tumor specimens obtained at surgery were snap frozen. Tumor DNA was extracted, and PCR was used to amplify regions containing 2 sites of recurrent activating somatic mutations in codons 201 and 227 in GNAS. Amplicons were bi-directionally sequenced and analyzed. GNAS mutations were present in 24/60 (40%) of tumors; these were arg201cys(n = 15), arg201ser(n = 2), arg201his(n = 2), gln227leu(n = 4), gln227arg(n = 1). Preoperative IGF-I levels (age-adjusted) were higher (p = 0.01), but GH levels were slightly higher (p = 0.18) in mutation positive vs. negative groups. Mutation positive tumors were somewhat smaller than negative tumors (p = 0.07). The proportion of tumors >2 cm was somewhat less among positive (8.3%) vs. negative tumors (25%) (p = 0.10). Neither mib proliferation index, the proportion of invasive tumors nor surgical remission rates differed in the groups. IGF-I normalization rate with somatostatin analog therapy was similar in positive (3 of 6) vs. negative (3 of 7) patients. GH secreting tumors harboring GNAS mutations had higher preoperative IGF-I levels, somewhat higher preoperative GH levels and tended to be smaller than tumors without mutations. Presence of a GNAS mutation did not predict a difference in a proliferation marker, surgical remission or response to somatostatin analog therapy.

    Funded by: NCRR NIH HHS: RR-00645; NIDDK NIH HHS: DK 073040, DK02561, DK064720, K24 DK073040, R01 DK064720

    Pituitary 2007;10;3;275-82

  • Large-scale mapping of human protein-protein interactions by mass spectrometry.

    Ewing RM, Chu P, Elisma F, Li H, Taylor P, Climie S, McBroom-Cerajewski L, Robinson MD, O'Connor L, Li M, Taylor R, Dharsee M, Ho Y, Heilbut A, Moore L, Zhang S, Ornatsky O, Bukhman YV, Ethier M, Sheng Y, Vasilescu J, Abu-Farha M, Lambert JP, Duewel HS, Stewart II, Kuehl B, Hogue K, Colwill K, Gladwish K, Muskat B, Kinach R, Adams SL, Moran MF, Morin GB, Topaloglou T and Figeys D

    Protana, Toronto, Ontario, Canada.

    Mapping protein-protein interactions is an invaluable tool for understanding protein function. Here, we report the first large-scale study of protein-protein interactions in human cells using a mass spectrometry-based approach. The study maps protein interactions for 338 bait proteins that were selected based on known or suspected disease and functional associations. Large-scale immunoprecipitation of Flag-tagged versions of these proteins followed by LC-ESI-MS/MS analysis resulted in the identification of 24,540 potential protein interactions. False positives and redundant hits were filtered out using empirical criteria and a calculated interaction confidence score, producing a data set of 6463 interactions between 2235 distinct proteins. This data set was further cross-validated using previously published and predicted human protein interactions. In-depth mining of the data set shows that it represents a valuable source of novel protein-protein interactions with relevance to human diseases. In addition, via our preliminary analysis, we report many novel protein interactions and pathway associations.

    Molecular systems biology 2007;3;89

  • Violating the splicing rules: TG dinucleotides function as alternative 3' splice sites in U2-dependent introns.

    Szafranski K, Schindler S, Taudien S, Hiller M, Huse K, Jahn N, Schreiber S, Backofen R and Platzer M

    Genome Analysis, Leibniz Institute for Age Research, Fritz Lipmann Institute, Beutenbergstr, 07745 Jena, Germany. szafrans@fli-leibniz.de

    Background: Despite some degeneracy of sequence signals that govern splicing of eukaryotic pre-mRNAs, it is an accepted rule that U2-dependent introns exhibit the 3' terminal dinucleotide AG. Intrigued by anecdotal evidence for functional non-AG 3' splice sites, we carried out a human genome-wide screen.

    Results: We identified TG dinucleotides functioning as alternative 3' splice sites in 36 human genes. The TG-derived splice variants were experimentally validated with a success rate of 92%. Interestingly, ratios of alternative splice variants are tissue-specific for several introns. TG splice sites and their flanking intron sequences are substantially conserved between orthologous vertebrate genes, even between human and frog, indicating functional relevance. Remarkably, TG splice sites are exclusively found as alternative 3' splice sites, never as the sole 3' splice site for an intron, and we observed a distance constraint for TG-AG splice site tandems.

    Conclusion: Since TGs splice sites are exclusively found as alternative 3' splice sites, the U2 spliceosome apparently accomplishes perfect specificity for 3' AGs at an early splicing step, but may choose 3' TGs during later steps. Given the tiny fraction of TG 3' splice sites compared to the vast amount of non-viable TGs, cis-acting sequence signals must significantly contribute to splice site definition. Thus, we consider TG-AG 3' splice site tandems as promising subjects for studies on the mechanisms of 3' splice site selection.

    Genome biology 2007;8;8;R154

  • Unexpected mosaicism of R201H-GNAS1 mutant-bearing cells in the testes underlie macro-orchidism without sexual precocity in McCune-Albright syndrome.

    Rey RA, Venara M, 4a1 Coutant R, Trabut JB, Rouleau S, Lahlou N, Sultan C, Limal JM and Lumbroso S

    Centro de Investigaciones Endocrinológicas, Hospital de Niños R Gutiérrez, Buenos Aires, Argentina.

    McCune-Albright syndrome (MAS), usually presenting with polyostotic bone dysplasia, café-au-lait skin lesions and sexual precocity, results from a somatic activating mutation of the GNAS1 gene, which encodes the Gs-alpha protein involved in signalling of several G-protein-coupled receptors. The clinical spectrum depends on tissue distribution of mutant-bearing cells. Sexual precocity has been ascribed to the occurrence of a mutant GNAS1 allele in the gonadal anlage, from which all somatic cells of the differentiated gonads arise. In boys, precocious activation of Leydig cell androgen secretion results in pubertal spermatogenesis, leading to testicular enlargement, and in the development of secondary sex characteristics. However, sexual precocity is rare in MAS males while isolated testicular enlargement is frequently observed. We recently reported the case of a boy with macro-orchidism and signs of Sertoli cell hyperactivity but no signs of hyperandrogenism, which was unexpected since Gs-alpha is functional in both Sertoli and Leydig cel 5a8 ls. To understand its pathophysiology, we microdissected an available testicular biopsy to separate Sertoli from Leydig cells. The R201H-GNAS1 allele was present only in Sertoli cells, resulting in isolated Sertoli cell hyperfunction, evidenced by increased AMH expression and cell hyperplasia leading to prepubertal macro-orchidism, with no signs of Leydig cell activation. The different early embryologic origin of precursors contributing to Sertoli and Leydig cell lineages may underlie the differential existence of the mutated GNAS1 gene. Lack of occurrence of the mutation in Leydig cells may explain why sexual precocity is rarely observed in boys with MAS.

    Human molecular genetics 2006;15;24;3538-43

  • Mutations in the Gs alpha gene causing hormone resistance.

    Mantovani G and Spada A

    Endocrine Unit, Department of Medical Sciences, University of Milan, Fondazione Ospedale Maggiore, Policlinico, Mangiagalli e Regina Elena IRCCS, Via F. Sforza, 35, 20122 Milan, Italy. giovanna.mantovani@unimi.it

    G-protein-coupled receptors (GPCRs) and G proteins mediate the effects of a number of hormones of relevance to endocrinology. Genes encoding these molecules may be targets of loss- or gain-of-function mutations, resulting in endocrine disorders. The only mutational change of G proteins so far unequivocally associated with endocrine disorders occurs in the Gsalpha gene (GNAS1, guanine nucleotide binding protein alpha stimulating activity polypeptide 1), which activates cyclic AMP (cAMP)-dependent pathways. Heterozygous loss-of-function mutations of GNAS1 in the active maternal allele cause resistance to hormones acting through Gsalpha-coupled GPCRs, whereas somatic gain-of-function mutations cause proliferation of endocrine cells recognizing cAMP as mitogen. This review will focus on inactivating mutations leading to hormone resistance syndromes, i.e., pseudohypoparathyroidism types Ia and Ib.

    Best practice & research. Clinical endocrinology & metabolism 2006;20;4;501-13

  • Activation of STAT3 by G alpha(s) distinctively requires protein kinase A, JNK, and phosphatidylinositol 3-kinase.

    Liu AM, Lo RK, Wong CS, Morris C, Wise H and Wong YH

    Department of Biochemistry, Molecular Neuroscience Center, Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.

    Signal transducer and activator of transcription 3 (STAT3) can be stimulated by several G(s)-coupled receptors, but the precise mechanism of action has not yet been elucidated. We therefore examined the ability of Galpha(s)Q226L (Galpha(s)QL), a constitutively active mutant of Galpha(s), to stimulate STAT3 Tyr705 and Ser727 phosphorylations in human embryonic kidney 293 cells. Apart from Galpha(s)QL, the stimulation of Galpha(s) by cholera toxin or beta2-adrenergic receptor and the activation of adenylyl cyclase by forskolin, (Sp)-cAMP, or dibutyryl-cAMP all promoted both STAT3 Tyr705 and Ser727 phosphorylations. Moreover, the removal of Galpha(s) by RNA interference significantly reduced the beta2-adrenergic receptor-mediated STAT3 phosphorylations, denoting its capacity to regulate STAT3 activation by a G protein-coupled receptor. The possible downstream signaling molecules involved were assessed by using specific inhibitors and dominant negative mutants. Induction of STAT3 Tyr705 and Ser727 phosphorylations by Galpha(s)QL was suppressed by inhibition of protein kinase A, Janus kinase 2/3, Rac1, c-Jun N-terminal kinase (JNK), or phosphatidylinositol 3-kinase, and a similar profile was observed in response to beta2-adrenergic receptor stimulation. In contrast to the Galpha16-mediated regulation of STAT3 in HEK 293 cells (Lo, R. K., Cheung, H., and Wong, Y. H. (2003) J. Biol. Chem. 278, 52154-52165), the Galpha(s)-mediated responses, including STAT3-driven luciferase activation, were resistant to inhibition of phospholipase Cbeta. Surprisingly, Galpha(s)-mediated phosphorylation at Tyr705, but not at Ser727, was resistant to inhibition of c-Src, Raf-1, and MEK1/2 as well as to the expression of dominant negative Ras. Therefore, as with other Galpha-mediated activations of STAT3, the stimulatory signal arising from Galpha(s) is transduced via multiple signaling pathways. However, unlike the mechanisms employed by Galpha(i) and Galpha(14/16), Galpha(s) distinctively requires protein kinase A, JNK, and phosphatidylinositol 3-kinase for STAT3 activation.

    The Journal of biological chemistry 2006;281;47;35812-25

  • The GNAS1 T393C polymorphism is associated with disease progression and survival in chronic lymphocytic leukemia.

    Frey UH, Nückel H, Sellmann L, Siemer D, Küppers R, Dürig J, Dührsen U and Siffert W

    Institut für Pharmakogenetik, Universitätsklinikum Essen, Hufelandstrasse 55, D-45122 Essen, Germany. Ulrich.Frey@uni-essen.de

    Purpose: B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of monoclonal mature B cells. The G protein Galphas subunit has been linked to proapoptotic processes in cancer cell lines. The TT genotype of the GNAS1 T393C polymorphism is associated with increased Galphas transcript levels and a more favorable clinical course in different solid cancers.

    We retrospectively genotyped 144 patients with B-CLL to examine a potential association between T393C genotypes with progression-free survival (time from diagnosis to initiation of chemotherapy) and overall survival.

    Results: The C-allele frequency in the patient group was 0.57 and not significantly different from that of healthy blood donors. Median progression-free survival was significantly different between genotypes (TT 130 months; TC 100 months; CC 31 months; P = 0.0066). Multivariable analysis showed that besides of ZAP-70 (P = 0.005) and Binet stage (P < 0.001), the T393C polymorphism was an independent prognostic factor for progression-free survival [hazard ratio (HR) CC versus TT 2.7; P = 0.010]. In Binet A stages, ZAP-70-positive patients with CC genotypes had a HR of 4.4 to receive first therapy compared with ZAP-70-negative patients with T-alleles (P = 0.0001). Regarding overall survival, CC genotypes (median overall survival, 197 months) were at highest risk for death compared with T-alleles (median overall survival, 310 months) in both univariate (HR, 4.8; P < 0.0001) and multivariable analysis (HR, 5.6; P = 0.002).

    Conclusions: Here, we show that the GNAS1 T393C status is a novel independent prognostic marker in patients with B-CLL. These results could help to define patients who could benefit from an early individualized therapy.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2006;12;19;5686-92

  • Effects of dopamine receptor type 1 and Gs protein alpha subunit gene polymorphisms on blood pressure at rest and in response to stress.

    Lu Y, Zhu H, Wang X, Snieder H, Huang Y, Harshfield GA, Treiber FA and Dong Y

    Georgia Prevention Institute, Department of Pediatrics, Medical College of Georgia, Augusta, GA 30912-3715, USA.

    Background: Exaggerated blood pressure (BP) response to behavioral stress has been recognized as an independent predictor of increased BP levels in human subjects. The coupling of dopamine receptor type 1 (DRD1) with stimulatory G-proteins plays an important role in BP regulation. Therefore, we investigated whether the A-48G polymorphism of the DRD1 gene and the T393C polymorphism of the Gs protein alpha subunit (GNAS) gene influenced BP levels at rest and in response to stress.

    Methods: A total of 912 white and African American (44.5%) twin subjects (17.4 +/- 3.4 years) were genotyped. Systolic and diastolic BP were measured at rest and during two 10-min stress tasks (a social competence interview and a virtual reality car driving simulation test). Regular association analyses and sibpair transmission disequilibrium tests were performed. The two polymorphisms, A-48G (DRD1) and T393C (GNAS), were genotyped by polymerase chain reaction with restriction digestion enzymes.

    Results: A dominant BP-lowering effect of the -48G allele was observed on diastolic BP at rest (P = .032) and in response to the car driving simulation test (P = .046). The 393C allele was associated with higher systolic BP levels during the social competence interview (P = .024) and the car driving simulation test (P = .016). There were no statistical significances between the two loci for systolic and diastolic BP at rest and during stress.

    Conclusions: Our findings suggest that DRD1 and GNAS loci contribute to BP regulation at rest, and in particular, in response to behavioral stress. The BP measurement during behavioral stress may have added value for gene association studies.

    Funded by: NHLBI NIH HHS: HL076723, HL69999, R01HL56622

    American journal of hypertension 2006;19;8;832-6

  • Runx2 regulates the expression of GNAS on SaOs-2 cells.

    Bertaux K, Broux O, Chauveau C, Hardouin P, Jeanfils J and Devedjian JC

    LR2B-Laboratoire de Recherche sur les Biomatériaux et les Biotechnologies, Université du Littoral Côte d'Opale, INSERM ERI002-EA2603, Quai Masset, Bassin Napoléon, 62327 BP 120 Boulogne-sur-mer Cedex, France.

    Runx2 is a key regulator of osteoblast-specific gene expression and controls the expression of multiple target genes during osteoblast differentiation. Although some transcriptional targets for Runx2 are known, it is believed that the osteogenic action of Runx2 is mediated by additional target genes, and increasing studies are performed in order to identify such Runx2-responsive genes. To identify genes following the inhibition of Runx2 in osteoblastic cell line, SaOs-2 was stably transfected with a dominant negative mutant of Runx2 (Deltacbfa1) under the control of a strong promoter. Comparison of gene expression patterns by differential display on selected SaOs-2 clones allowed us to observe that GNAS mRNA which encodes for the Gsalpha protein is overexpressed (5 to 8 fold) in cells presenting high levels of Deltacbfa1. This overexpression was also observed at the protein level and seemed to be reflected by an increased basal cAMP level. Gel shift experiments performed in this study indicate that Runx2 is able to bind to the promoter of GNAS, suggesting a direct regulation at the transcriptional level. Well-described GNAS mutations like fibrous dysplasia or Albright hereditary osteodystrophy are linked to abnormality in osteoblast function, and numerous evidences showed that Gsalpha coupled adrenergic receptors increase the expression of osteotrophic factors and regulate bone mass. Regulation of Gsalpha protein by Runx2 seems to be of particular interest considering the increasing evidences on bone metabolism regulation by G proteins.

    Bone 2006;38;6;943-50

  • Albright's hereditary osteodystrophy. 398

    Wilson LC

    Clinical & Molecular Genetics Unit, Great Ormond Street Hospital and Institute of Child Health, London, UK. WilsoL@gosh.nhs.uk

    Journal of pediatric endocrinology & metabolism : JPEM 2006;19 Suppl 2;671-3

  • Coding GNAS mutations leading to hormone resistance impair in vitro agonist- and cholera toxin-induced adenosine cyclic 3',5'-monophosphate formation mediated by human XLalphas.

    Linglart A, Mahon MJ, Kerachian MA, Berlach DM, Hendy GN, Jüppner H and Bastepe M

    Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, 02114, USA.

    Most loss of function mutations of GNAS identified in different forms of pseudohypoparathyroidism disrupt not only the stimulatory G protein alpha-subunit (Gsalpha), but also its paternally expressed variant, XLalphas. However, the possibility that XLalphas deficiency contributes to disease pathogenesis has remained unexplored. We therefore examined the signaling property of human XLalphas and the effects of one novel (XLalphas(H704P) or Gsalpha(H362P)) and two previously described (XLalphas(DelI724) and XLalphas(Y733X) or Gsalpha(DelI382) and Gsalpha(Y391X), respectively) GNAS mutations on either XLalphas or Gsalpha activity. Confocal immunofluorescence microscopy detected human XLalphas immunoreactivity at the plasma membrane of transduced mouse embryonic fibroblasts null for endogenous Gsalpha and XLalphas (Gnas(E2-/E2-) cells). Cholera toxin- and isoproterenol-induced cAMP accumulation in Gnas(E2-/E2-) cells transiently expressing wild-type human XLalphas was similar to that in cells transiently expressing wild-type Gsalpha. Human XLalphas, like Gsalpha, mediated PTH-induced cAMP accumulation in Gnas(E2-/E2-) cells coexpressing PTH receptor type 1 and either of these proteins. Moreover, overexpression of human XLalphas or Gsalpha markedly enhanced the PTH-induced cAMP accumulation in opossum kidney cells that endogenously express PTH receptor type 1. In contrast, each XLalphas mutant failed to mediate isoproterenol- and PTH-induced cAMP accumulation in transduced Gnas(E2-/E2-) cells. XLalphas(DelI724) showed a reduced cholera toxin response over the basal level compared with wild-type XLalphas, and XLalphas(H704P) completely failed to respond to cholera toxin. These findings were comparable to those observed with each corresponding Gsalpha mutant transiently expressed in Gnas(E2-/E2-) cells. Thus, mutations that typically inactivate Gsalpha also impair XLalphas activity, consistent with a possible role for XLalphas deficiency in diseases caused by paternal GNAS mutations.

    Funded by: NIDDK NIH HHS: K01 DK062973, K01-DK-062973; PHS HHS: R01-46718-10

    Endocrinology 2006;147;5;2253-62

  • Different mutations within or upstream of the GNAS locus cause distinct forms of pseudohypoparathyroidism.

    Jüppner H and Bastepe M

    Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA. hjueppner@partners.org

    The term pseudohypoparathyroidism (PHP) refers to different disorders that are caused by mutations within GNAS or upstream of this complex genetic locus. GNAS gives rise to several different transcripts, including Gs alpha (alpha-subunit of the heterotrimeric stimulatory G protein), XL alpha s (extra-large variant of Gs alpha), and several additional sense and antisense transcripts. The complexity of the GNAS locus is furthermore reflected by a parent-specific methylation pattern of most of its different promoters. PHP can be divided into two major groups, PHP type Ia (PHP-Ia) and PHP type Ib (PHP-Ib). PHP-Ia is caused by heterozygous mutations affecting one of the 13 GNAS exons encoding Gs alpha. In contrast, PHP-Ib is caused by heterozygous deletions within STX16, the gene encoding syntaxin 16, which is located more than 220 kb upstream of GNAS, or by deletions within GNAS involving exon NESP55 and two of the antisense exons. In either form of PHP, hormonal resistance develops only after maternal inheritance of the mutation, while paternal inheritance of the same molecular defect is not associated with endocrine abnormalities. In most familial cases of PHP-Ib, there is a loss of exon A/B methylation combined with active A/B transcription from both parental alleles, which leads to suppression of Gs alpha transcription in the proximal renal tubules and, therefore, PTH resistance.

    Journal of pediatric endocrinology & metabolism : JPEM 2006;19 Suppl 2;641-6

  • Genetics of McCune-Albright syndrome.

    de Sanctis L, Delmastro L, Russo MC, Matarazzo P, Lala R and de Sanctis C

    Department of Pediatric Sciences, University o 1468 f Torino, Italy. luisa.desanctis@unito.it

    McCune-Albright syndrome (MAS) is a rare proteiform disease due to postzygotic, somatic mutations at codon R201 of the GNAS1 gene that results in cellular mosaicism. Different methods have been used in the molecular analysis of DNA samples from several tissues of patients with one or more MAS signs, with various mutation detection rates. We review data from the literature to investigate whether patient inclusion criteria for GNAS1 analysis, the molecular methods used to search for R201 mutations, and the type of tissues analysed, can influence the mutation detection rate in MAS. Our study indicates that to overcome the problems related to GNAS1 analysis in MAS, sensitive and specific molecular methods must be used to look for the mutation from all available affected tissues and from easily accessible tissues, and even more so in the presence of atypical and monosymptomatic forms of MAS.

    Journal of pediatric endocrinology & metabolism : JPEM 2006;19 Suppl 2;577-82

  • Genetics of pseudohypoparathyroidism types Ia and Ic.

    Aldred MA

    Division of Medical Genetics, University of Leicester and Leicestershire Genetics Service, University Hospitals of Leicester NHS Trust, Leicester, UK. aldredm@ccf.org

    Pseudohypoparathyroidism (PHP) types Ia and Ic result from heterozygous inactivating mutations of Gs alpha, the alpha-subunit of the heterotrimeric stimulatory G-protein, Gs. Both are characterized by a combination of Albright's hereditary osteodystrophy and, when the mutation is maternally inherited, end-organ resistance to multiple hormones. Due to complex tissue-specific imprinting of Gs alpha, paternally-derived mutations do not usually lead to hormone resistance. More than 100 mutations have been characterized in patients with PHP-Ia and one mutation in type Ic. These are scattered throughout the gene, with one significant mutational hotspot in exon 7. Identification of mutations in a clinical service setting is important for accurate genetic counselling and clinical management of affected families. However, only 70-80% of mutations are identified by direct sequencing of coding exons and splice junctions. Screening for whole exon deletions and intronic or regulatory mutations in mutation-negative families is therefore now an important priority to establish the full mutational spectrum in these conditions.

    Journal of pediatric endocrinology & metabolism : JPEM 2006;19 Suppl 2;635-40

  • The T393C polymorphism of the GNAS1 gene is associated with deficit schizophrenia in an Italian population sample.

    Minoretti P, Politi P, Coen E, Di Vito C, Bertona M, Bianchi M and Emanuele E

    Interdepartmental Center for Research in Molecular Medicine (CIRMC), University of Pavia, Viale Taramelli 24, I-27100 Pavia, Italy.

    Programmed cell death and alterations in intracellular G-protein signaling may be involved in the pathophysiology of schizophrenia. The Galphas subunit of heterotrimeric G-proteins, encoded by the gene GNAS1, may play a role in both of these processes. Additionally, transgenic mice expressing a constitutively active form of Galphas provide a reliable model of certain endophenotypes of schizophrenia. To investigate whether the functional single nucleotide polymorphism T393C in GNAS1 gene could affect risk of schizophrenia, we examined its distribution in Italian subjects with (n=383) and without (n=400) schizophrenia. We also evaluated whether a specific association could exist between the deficit (n=108) and nondeficit (n=275) forms of the disorder. The alleles and genotypes frequency in the entire cohort of schizophrenic patients did not differ from that of controls. However, the frequency of the homozygous 393TT genotype was significantly higher in deficit schizophrenic patients (37.1%) compared to both nondeficit schizophrenic (22.5%, p=0.011) and controls (22.8%, p=0.015). This association with deficit schizophrenia persisted even after allowance for potential confounders [adjusted odds ratio (OR) for deficit schizophrenia: 2.06 (95% confidence interval (CI): 1.21-3.47), p=0.007]. Altogether, our data suggest that the GNAS1 T393C status could influence susceptibility for deficit schizophrenia in Italian subjects.

    Neuroscience letters 2006;397;1-2;159-63

  • Diversification of transcriptional modulation: large-scale identification and characterization of putative alternative promoters of human genes.

    Kimura K, Wakamatsu A, Suzuki Y, Ota T, Nishikawa T, Yamashita R, Yamamoto J, Sekine M, Tsuritani K, Wakaguri H, Ishii S, Sugiyama T, Saito K, Isono Y, Irie R, Kushida N, Yoneyama T, Otsuka R, Kanda K, Yokoi T, Kondo H, Wagatsuma M, Murakawa K, Ishida S, Ishibashi T, Takahashi-Fujii A, Tanase T, Nagai K, Kikuchi H, Nakai K, Isogai T and Sugano S

    Life Science Research Laboratory, Central Research Laboratory, Hitachi, Ltd., Kokubunji, Tokyo, 185-8601, Japan.

    By analyzing 1,780,295 5'-end sequences of human full-length cDNAs derived from 164 kinds of oligo-cap cDNA libraries, we identified 269,774 independent positions of transcriptional start sites (TSSs) for 14,628 human RefSeq genes. These TSSs were clustered into 30,964 clusters that were separated from each other by more than 500 bp and thus are very likely to constitute mutually distinct alternative promoters. To our surprise, at least 7674 (52%) human RefSeq genes were subject to regulation by putative alternative promoters (PAPs). On average, there were 3.1 PAPs per gene, with the composition of one CpG-island-containing promoter per 2.6 CpG-less promoters. In 17% of the PAP-containing loci, tissue-specific use of the PAPs was observed. The richest tissue sources of the tissue-specific PAPs were testis and brain. It was also intriguing that the PAP-containing promoters were enriched in the genes encoding signal transduction-related proteins and were rarer in the genes encoding extracellular proteins, possibly reflecting the varied functional requirement for and the restricted expression of those categories of genes, respectively. The patterns of the first exons were highly diverse as well. On average, there were 7.7 different splicing types of first exons per locus partly produced by the PAPs, suggesting that a wide variety of transcripts can be achieved by this mechanism. Our findings suggest that use of alternate promoters and consequent alternative use of first exons should play a pivotal role in generating the complexity required for the highly elaborated molecular systems in humans.

    Genome research 2006;16;1;55-65

  • Imprinting the Gnas locus.

    Plagge A and Kelsey G

    Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Babraham Research Campus, Cambridge, UK. antonius.plagge@bbsrc.ac.uk

    Gnas is an enigmatic and rather complex imprinted gene locus. A single transcription unit encodes three, and possibly more, distinct proteins. These are determined by overlapping transcripts from alternative promoters with different patterns of imprinting. The canonical Gnas transcript codes for Gsalpha, a highly conserved signalling protein and an essential intermediate in growth, differentiation and homeostatic pathways. Monoallelic expression of Gnas is highly tissue-restricted. The alternative transcripts encode XLalphas, an unusual variant of Gsalpha, and the chromogranin-like protein Nesp55. These transcripts are expressed specifically from the paternal and maternal chromosomes, respectively. Their existence in the Gnas locus might imply functional connections amongst them or with Gsalpha. In this review, we consider how imprinting of Gnas was discovered, the phenotypic consequences of mutations in each of the gene products, both in the mouse and human, and provide some conjectures to explain why this elaborate imprinted locus has evolved in this manner in mammals.

    Cytogenetic and genome research 2006;113;1-4;178-87

  • Polymorphisms of genes CYP2D6, ADRB1 and GNAS1 in pharmacokinetics and systemic effects of ophthalmic timolol. A pilot study.

    Nieminen T, Uusitalo H, Mäenpää J, Turjanmaa V, Rane A, Lundgren S, Ropo, Ron 1ec8 tu R, Lehtimäki T and Kähönen M

    Department of Pharmacological Sciences, Medical School, University of Tampere, 33014 Tampere, Finland. tuomo.nieminen@iki.fi

    Objective: To test the hypotheses that (1) CYP2D6 genotype is associated with pharmacokinetics of ophthalmic timolol and (2) variation in genotypes of ADRB1 (beta(1)-adrenoceptor) and GNAS1 (alpha-subunit of G-protein) modulate heart rate (HR), and systolic (SAP) and diastolic (DAP) arterial pressure responses to timolol.

    Methods: Nineteen glaucoma patients and eighteen healthy volunteers were treated with 0.5% aqueous and 0.1% hydrogel formulations of ophthalmic timolol using a randomised cross-over design. The participants conducted head-up tilt and maximum exercise test at four visits. Plasma concentration of timolol was measured twice for glaucoma patients and ten times for healthy volunteers on each visit. Also, the genotypes for CYP2D6, ADRB1 and GNAS1 were determined.

    Results: Among healthy volunteers using aqueous timolol, poor metabolisers (PMs, n=2) of CYP2D6 had higher maximum plasma concentrations (C(max), values 2.63 and 2.94 ng/ml), longer elimination half-lives ( T(1/2), 5.49 and 6.75 h), and higher area-under-curve (AUC, 19.54 and 23.25 ng.h/ml) than intermediate [IMs, n=6, mean+/-SD 1.73+/-0.59 ng/ml (not significant), 3.30+/-0.48 h, 11.32+/-3.72 ng.h/ml], extensive (EMs, n=8, 1.60+/-0.72 ng/ml, 3.24+/-1.24 h, 8.52+/-6.12 ng.h/ml) and ultra-rapid (UMs, n=2, values 1.23 and 1.67 ng/ml, 2.22 and 2.52 h, 6.16 and 6.94 ng.h/ml) metabolisers. The IMs, EMs and UMs did not differ from each other for any of the kinetic variables. Also, the elevation of HR from rest to maximum level tended to differ between PMs and IMs, and between PMs and UMs. The pharmacokinetics and pharmacodynamics between the CYP2D6 groups did not differ with statistical significance when hydrogel timolol was used. Upon head-up tilt, the Ser49 homozygotes (n=26) had higher SAP (P=0.03) and DAP (P<0.01) than the Gly carriers (n=11). The change in DAP from rest to maximum during exercise was lower (P<0.01) in subjects with CC alleles of GNAS1 (n=13) than those with at least one T allele (n=24).

    Conclusion: The CYP2D6 poor metabolisers may be more prone to systemic adverse events with aqueous timolol than extensive metabolisers. Since CYP2D6 genotyping is not routine clinical practice, using 0.1% timolol hydrogel instead of 0.5% aqueous preparation will increase patient safety.

    European journal of clinical pharmacology 2005;61;11;811-9

  • Expression of the GTP-binding protein (Galphas) is repressed by the nuclear factor kappaB RelA subunit in human myometrium.

    Chapman NR, Smyrnias I, Anumba DO, Europe-Finner GN and Robson SC

    School of Surgical and Reproductive Sciences, University of Newcastle-upon-Tyne, and Academic Unit of Reproductive and Developmental Medicine, Sheffield Teaching Hospitals NHS Trust, UK. n.r.chapman@sheffield.ac.uk

    In humans, the factors that govern the switch from myometrial quiescence to coordinated contractions at the initiation of labor are not well defined. The onset of parturition is itself associated with increases in a number of proinflammatory mediators, many of which are regulated by the nuclear factor kappaB (NF-kappaB) family of transcription factors. Recently, we have provided evidence that the RelA NF-kappaB subunit associates with protein kinase A in pregnant myometrial tissue, suggesting links with the Galphas/cAMP/protein kinase A pathway. TNFalpha is a potent activator of NF-kappaB, and levels of this cytokine are increased within the myometrium at term. In the current study, using primary cultures of myometrial ce 1f40 lls, TNFalpha was observed to repress expression of Galphas while, at the same time, stimulating NF-kappaB activity. Furthermore, this effect could be replicated by exposure to bacterial lipopolysaccharide and exogenous expression of RelA. Moreover, TNFalpha was seen to repress endogenous Galphas mRNA expression as judged by RT-PCR analyses. Using the chromatin immunoprecipitation assay, we show that RelA did not bind directly to the Galphas promoter. Significantly, expression of a coactivator protein, cAMP response element binding protein binding protein, relieved RelA-induced down-regulation of Galphas expression. Together, these data suggest that, in human myometrium, repression of the Galphas gene by NF-kappaB occurs through a non-DNA binding mechanism involving competition for limiting amounts of cellular coactivator proteins including cAMP response element binding protein binding protein.

    Funded by: Wellcome Trust

    Endocrinology 2005;11;4994-5002

  • Towards a proteome-scale map of the human protein-protein interaction network.

    Rual JF, Venkatesan K, Hao T, Hirozane-Kishikawa T, Dricot A, Li N, Berriz GF, Gibbons FD, Dreze M, Ayivi-Guedehoussou N, Klitgord N, Simon C, Boxem M, Milstein S, Rosenberg J, Goldberg DS, Zhang LV, Wong SL, Franklin G, Li S, Albala JS, Lim J, Fraughton C, Llamosas E, Cevik S, Bex C, Lamesch P, Sikorski RS, Vandenhaute J, Zoghbi HY, Smolyar A, Bosak S, Sequerra R, Doucette-Stamm L, Cusick ME, Hill DE, Roth FP and Vidal M

    Center for Cancer Systems Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, Massachusetts 02115, USA.

    Systematic mapping of protein-protein interactions, or 'interactome' mapping, was initiated in model organisms, starting with defined biological processes and then expanding to the scale of the proteome. Although far from complete, such maps have revealed global topological and dynamic features of interactome networks that relate to known biological properties, suggesting that a human interactome map will provide insight into development and disease mechanisms at a systems level. Here we describe an initial version of a proteome-scale map of human binary protein-protein interactions. Using a stringent, high-throughput yeast two-hybrid system, we tested pairwise interactions among the products of approximately 8,100 currently available Gateway-cloned open reading frames and detected approximately 2,800 interactions. This data set, called CCSB-HI1, has a verification rate of approximately 78% as revealed by an independent co-affinity purification assay, and correlates significantly with other biological attributes. The CCSB-HI1 data set increases by approximately 70% the set of available binary interactions within the tested space and reveals more than 300 new connections to over 100 disease-associated proteins. This work represents an important step towards a systematic and comprehensive human interactome project.

    Funded by: NCI NIH HHS: R33 CA132073; NHGRI NIH HHS: P50 HG004233, R01 HG001715, RC4 HG006066, U01 HG001715; NHLBI NIH HHS: U01 HL098166

    Nature 2005;437;7062;1173-8

  • Oscillating evolution of a mammalian locus with overlapping reading frames: an XLalphas/ALEX relay.

    Nekrutenko A, Wadhawan S, Goetting-Minesky P and Makova KD

    Department of Biochemistry and Molec 1516 ular Biology, Pennsylvania State University, University Park, Pennsylvania, USA. anton@bx.psu.edu

    XLalphas and ALEX are structurally unrelated mammali 732 an proteins translated from alternative overlapping reading frames of a single transcript. Not only are they encoded by the same locus, but a specific XLalphas/ALEX interaction is essential for G-protein signaling in neuroendocrine cells. A disruption of this interaction leads to abnormal human phenotypes, including mental retardation and growth deficiency. The region of overlap between the two reading frames evolves at a remarkable speed: the divergence between human and mouse ALEX polypeptides makes them virtually unalignable. To trace the evolution of this puzzling locus, we sequenced it in apes, Old World monkeys, and a New World monkey. We show that the overlap between the two reading frames and the physical interaction between the two proteins force the locus to evolve in an unprecedented way. Namely, to maintain two overlapping protein-coding regions the locus is forced to have high GC content, which significantly elevates its intrinsic evolutionary rate. However, the two encoded proteins cannot afford to change too quickly relative to each other as this may impair their interaction and lead to severe physiological consequences. As a result XLalphas and ALEX evolve in an oscillating fashion constantly balancing the rates of amino acid replacements. This is the first example of a rapidly evolving locus encoding interacting proteins via overlapping reading frames, with a possible link to the origin of species-specific neurological differences.

    PLoS genetics 2005;1;2;e18

  • Structure of Galpha(i1) bound to a GDP-selective peptide provides insight into guanine nucleotide exchange.

    Johnston CA, Willard FS, Jezyk MR, Fredericks Z, Bodor ET, Jones MB, Blaesius R, Watts VJ, Harden TK, Sondek J, Ramer JK and Siderovski DP

    Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.

    Heterotrimeric G proteins are molecular switches that regulate numerous signaling pathways involved in cellular physiology. This characteristic is achieved by the adoption of two principal states: an inactive, GDP bound state and an active, GTP bound state. Under basal conditions, G proteins exist in the inactive, GDP bound state; thus, nucleotide exchange is crucial to the onset of signaling. Despite our understanding of G protein signaling pathways, the mechanism of nucleotide exchange remains elusive. We employed phage display technology to identify nucleotide state-dependent Galpha binding peptides. Herein, we report a GDP-selective Galpha binding peptide, KB-752, that enhances spontaneous nucleotide exchange of Galpha(i) subunits. Structural determination of the Galpha(i1)/peptide complex reveals unique changes in the Galpha switch regions predicted to enhance nucleotide exchange by creating a GDP dissociation route. Our results cast light onto a potential mechanism by which Galpha subunits adopt a conformation suitable for nucleotide exchange.

    Funded by: NIGMS NIH HHS: P01 GM 065533, P01 GM065533, R01 GM 062338, R01 GM062338

    Structure (London, England : 1993) 2005;13;7;1069-80

  • Real-time monitoring of receptor and G-protein interactions in living cells.

    Galés C, Rebois RV, Hogue M, Trieu P, Breit A, Hébert TE and Bouvier M

    Department of Biochemistry, Université de Montréal, P.O. Box 6128 Down-town station, Montréal, H3C 3J7, Canada.

    G protein-coupled receptors (GPCRs) represent the largest family of proteins involved in signal transduction. Here we present a bioluminescence resonance energy transfer (BRET) assay that directly monitors in real time the early interactions between human GPCRs and their cognate G-protein subunits in living human cells. In addition to detecting basal precoupling of the receptors to Galpha-, Gbeta- and Ggamma-subunits, BRET measured very rapid ligand-induced increases in the interaction between receptor and Galphabetagamma-complexes (t(1/2) approximately 300 ms) followed by a slower (several minutes) decrease, reflecting receptor desensitization. The agonist-promoted increase in GPCR-Gbetagamma interaction was highly dependent on the identity of the Galpha-subunit present in the complex. Therefore, this G protein-activity biosensor provides a novel tool to directly probe the dynamics and selectivity of receptor-mediated, G-protein activation-deactivation cycles that could be advantageously used to identify ligands for orphan GPCRs.

    Nature methods 2005;2;3;177-84

  • GSPalpha mutations in Mexican patients with acromegaly: potential impact on long term prognosis.

    Mendoza V, Sosa E, Espinosa-de-Los-Monteros AL, Salcedo M, Guinto G, Cheng S, Sandoval C and Mercado M

    Endocrinology Service, Experimental Endocrinology Unit, Hospital de Especialidades, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Aristòteles 68, Colonia Polanco 11560, México City, México.

    Objective: The frequency of activating mutations of the GSPalpha gene as the etiology of GH-secreting pituitary adenomas has been the subject of important ethnogenetic variability. Whereas up to 40% of Caucasian patients with acromegaly have tumors which harbor these somatic mutations, their prevalence among Asian populations is much lower. The correlation between the presence of these mutations and the clinical and biological behavior of these tumors has also been a matter of controversy. In the present study, we investigated the prevalence of GSPalpha mutations in GH-secreting tumors obtained from a genetically homogenous population of Mexican patients with acromegaly. We also sought to establish whether or not the presence of these mutations correlates in any way with the clinical or biochemical characteristics of the disease.

    Fifty eight GH-secreting pituitary adenomas were examined for the presence of point mutations in either codon 201 or 227 of the GSPalpha gene, using PCR and direct sequencing of DNA extracted from either fresh or paraffin-embedded tissues. Patients were prospectively followed clinically and biochemically for up to nine years after pituitary surgery.

    Results: Heterozygous point mutations in exon 8 (codon 201) were found in 11 patients (19%), and no molecular alterations were evident in exon 9. The frequency and severity of the different clinical features of acromegaly did not differ between patients with and without GSPalpha mutations. Patients with and without mutations had pre-operative GH and IGF-I elevations of similar magnitude, and although microadenomas appeared to be more frequent among patients with GSPalpha mutations, this did not reach statistical significance. Upon short-term follow-up, biochemical cure (normal age- and gender-adjusted IGF-I and post-glucose GH below 1 ng/mL) was similarly achieved in both groups. After 3-9 years of post-operative follow up however, a significantly greater proportion of patients with the mutation achieved a "safe" basal GH value (100% vs 33%, p=0.001) as well a lower nadir post-glucose GH (0.53+/-0.5 vs 2.9+/-6.2 ng/mL, p=0.04) although the rate of IGF-1 normalization did not differ between the 2 groups.

    Conclusions: Our results show that the prevalence of GSPalpha mutations in Mexican patients with acromegaly is intermediate between that found in Asian and Caucasian populations. In this well-defined genetic population the presence of codon 201 mutations appeared to be associated with a greater probability of achieving a "safe" GH value upon long-term follow-up.

    Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society 2005;15;1;28-32

  • Distinct patterns of abnormal GNAS imprinting in familial and sporadic pseudohypoparathyroidism type IB.

    Liu J, Nealon JG and Weinstein LS

    Metabolic Diseases Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

    Pseudohypoparathyroidism type IB (PHPIB) is associated with abnormal imprinting of GNAS, the gene encoding the heterotrimeric G protein Gsalpha and other alternative products. The gene contains three differentially methylated regions (DMRs) located upstream of the Gsalpha promoter (from upstream to downstream): the paternally methylated NESP55 promoter region, the maternally methylated NESP antisense (NESPAS)/XLalphas promoter region and the maternally methylated exon 1A region located just upstream of the Gsalpha promoter. We have now performed a detailed analysis of the GNAS methylation profile in 20 unrelated PHPIB probands. Consistent with prior results, all have loss of exon 1A imprinting (a paternal epigenotype on both alleles). All five probands with familial disease had a deletion mutation within the closely linked STX16 gene and a GNAS imprinting defect involving only the exon 1A region. In contrast, the STX16 mutation was absent in all sporadic cases. The majority of these patients had abnormal imprinting of the more upstream regions in addition to the exon 1A imprinting defect, with eight of 15 having a paternal epigenotype on both alleles throughout the GNAS locus. In virtually all cases, the imprinting status of the NESP55 and NESPAS/XLalphas promoters is concordant, suggesting that their imprinting is co-regulated, whereas the imprinting of the NESPAS/XLalphas promoter region and XLalphas first exon is not always concordant even though they are closely linked and lie within the same DMR. Familial and sporadic forms of PHPIB have distinct GNAS imprinting patterns that occur through different defects in the imprinting mechanism.

    Human molecular genetics 2005;14;1;95-102

  • Deletion of the NESP55 differentially methylated region causes loss of maternal GNAS imprints and pseudohypoparathyroidism type Ib.

    Bastepe M, Fröhlich LF, Linglart A, Abu-Zahra HS, Tojo K and Ward LM

    Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA. bastepe@helix.mgh.harvard.edu <bastepe@helix.mgh.harvard.edu&gt;

    Epigenetic defects in the imprinted GNAS cluster are associated with pseudohypoparathyroidism type Ib. In two kindreds with this disorder, we now report deletions that remove the differentially methylated region encompassing exon NESP55 and exons 3 and 4 of the antisense transcript. When inherited from a female, either deletion abolishes all maternal GNAS imprints and derepresses maternally silenced transcripts, suggesting that the deleted region contains a cis-acting element that controls imprinting of the maternal GNAS allele.

    Nature genetics 2005;37;1;25-7

  • GNAS locus and pseudohypoparathyroidism.

    Bastepe M and H

    Endocrine Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. bastepe@helix.mgh.harvard.edu

    Pseudohypoparathyroidism (PHP) is characterized by hypocalcemia and hyperphosphatemia due to resistance to parathyroid hormone (PTH). Patients with PHP-Ia often present with additional hormonal resistance and show characteristic physical features that are collectively termed Albright's hereditary osteodystrophy (AHO). These features are also present in pseudopseudohypoparathyroidism (PPHP), but patients affected by this disorder do not show hormone resistance. PHP-Ib patients, on the other hand, present predominantly with renal PTH resistance and lack any features of AHO. Most of these PHP forms are caused by defects in GNAS (20q13.3), an imprinted gene locus with multiple transcriptional units. PHP-Ia and PPHP are caused by heterozygous inactivating mutations in those exons of GNAS encoding the alpha subunit of the stimulatory guanine nucleotide-binding protein (Gsalpha), and the autosomal dominant form of PHP-Ib (AD-PHP-Ib) is caused by heterozygous mutations disrupting a long-range imprinting control element of GNAS. Expressed nearly in all cells, Gsalpha plays essential roles in a multitude of physiological processes. Its expression in renal proximal tubules occurs predominantly from the maternal allele, and this tissue- and parent-specific imprinting of Gsalpha is an important determinant of hormone resistance in kindreds with PHP-Ia/PPHP and AD-PHP-Ib.

    Hormone research 2005;63;2;65-74

  • Using molecular tools to dissect the role of Galphas in sensitization of AC1.

    Vortherms TA, Nguyen CH, Berlot CH and Watts VJ

    Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, USA.

    Short-term activation of Galpha(i/o)-coupled receptors inhibits adenylyl cyclase, whereas persistent activation of Galpha(i/o)-coupled receptors results in a compensatory sensitization of adenylyl cyclase activity after subsequent activation by Galpha(s) or forskolin. Several indirect observations have suggested the involvement of increased Galpha(s)-adenylyl cyclase interactions in the expression of sensitization; however, evidence supporting a direct role for Galpha(s) has not been well established. In the present report, we used two genetic approaches to further examine the role of Galpha(s) in heterologous sensitization of Ca(2+)-sensitive type 1 adenylyl cyclase (AC1). In the first approach, we constructed Galpha(s)-insensitive mutants of AC1 (F293L and Y973S) that retained sensitivity to Ca2+ and forskolin activation. Persistent (2 h) activation of the D2 dopamine receptor resulted in a significant augmentation of basal or Ca(2+)- and forskolin-stimulated AC1 activity; however, sensitization of Galpha(s)-insensitive mutants of AC1 was markedly reduced compared with wild-type AC1. In the second strategy, we examined the requirement of an intact receptor-Galpha(s) signaling pathway for the expression of sensitization using dominant-negative Galpha(s) mutants (alpha3beta5 G226A/A366S or alpha3beta5 G226A/E268A/A366S) to disrupt D1 dopamine receptor activation of recombinant AC1. D1 dopamine receptor-Galpha(s) signaling was attenuated in the presence of alpha3beta5 G226A/A366S or alpha3beta5 G226A/E268A/A366S, but D2 agonist-induced sensitization of Ca(2+)-stimulated AC1 activity was not altered. Together, the present findings directly support the hypothesis that the expression of sensitization of AC1 involves Galpha(s)-adenylyl cyclase interactions.

    Funded by: NIMH NIH HHS: MH60397

    Molecular pharmacology 2004;66;6;1617-24

  • Complex haplotype structure of the human GNAS gene identifies a recombination hotspot centred on a single nucleotide polymorphism widely used in association studies.

    Yang W, White B, Spicer EK, Weinstein BL and Hildebrandt JD

    Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston, South Carolina, USA.

    The alpha subunit of the heterotrimeric G protein Gs (Gsalpha) is involved in numerous physiological processes and is a primary determinant of cellular responses to extracellular signals. Genetic variations in the Gsalpha gene may play an important role in complex diseases and drug responses. To characterize the genetic diversity in this locus, we resequenced exons and flanking introns of the gene in 44 genomic samples and analysed the haplotype structure of the gene in an additional 50 African-Americans and 50 Caucasians. Significant differences in allele frequency for nearly all the genotyped single nucleotide polymorphism (SNPs) were detected between the two ethnic groups. Linkage disequilibrium (LD) analysis of this locus revealed two haplotype blocks characterized by strong LD and reduced haplotype diversity, especially in Caucasians. Between the two blocks is a narrow (approximately 3 kb) recombination hotspot centred on exons 4 and 5, and a widely used genetic marker in association studies in this region (rs7121) was in linkage equilibrium with the rest of the gene. The haplotype structure of the GNAS locus warrants reevaluation of previous association studies that used marker rs7121 and affects choice of SNP markers to be used in future studies of this locus.

    Funded by: NIDDK NIH HHS: DK37219; NINDS NIH HHS: NS38534

    Pharmacogenetics 2004;14;11;741-7

  • Vectorial proteomics reveal targeting, phosphorylation and specific fragmentation of polymerase I and transcript release factor (PTRF) at the surface of caveolae in human adipocytes.

    Aboulaich N, Vainonen JP, Strålfors P and Vener AV

    Division of Cell Biology and Diabetes Research Centre, Faculty of Health Sciences, Linköping University, SE58185 Linköping, Sweden.

    Caveolae, the specialized invaginations of plasma membranes, formed sealed vesicles with outwards-orientated cytosolic surface after isolation from primary human adipocytes. This morphology allowed differential, vectorial identification of proteins at the opposite membrane surfaces by proteolysis and MS. Extracellular-exposed caveolae-specific proteins CD36 and copper-containing amine oxidase were concealed inside the vesicles and resisted trypsin treatment. The cytosol-orientated caveolins were efficiently digested by trypsin, producing peptides amenable to direct MS sequencing. Isolation of peripheral proteins associated with the cytosolic surface of caveolae revealed a set of proteins that contained nuclear localization signals, leucine-zipper domains and PEST (amino acid sequence enriched in proline, glutamic acid, serine and threonine) domains implicated in regulation by proteolysis. In particular, PTRF (polymerase I and transcript release factor) was found as a major caveolae-associated protein and its co-localization with caveolin was confirmed by immunofluorescence confocal microscopy. PTRF was present at the surface of caveolae in the intact form and in five different truncated forms. Peptides (44 and 45 amino acids long) comprising both the PEST domains were sequenced by nanospray-quadrupole-time-of-flight MS from the full-length PTRF, but were not found in the truncated forms of the protein. Two endogenous cleavage sites corresponding to calpain specificity were identified in PTRF; one of them was in a PEST domain. Both cleavage sites were flanked by mono- or diphosphorylated sequences. The phosphorylation sites were localized to Ser-36, Ser-40, Ser-365 and Ser-366 in PTRF. Caveolae of human adipocytes are proposed to function in targeting, relocation and proteolytic control of PTRF and other PEST-domain-containing signalling proteins.

    The Biochemical journal 2004;383;Pt 2;237-48

  • Mutation of the highly conserved Arg165 and Glu168 residues of human Gsalpha disrupts the alphaD-alphaE loop and enhances basal GDP/GTP exchange rate.

    Hinrichs MV, Montecino M, Bunster M and Olate J

    Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.

    G protein signalling regulates a wide range of cellular processes such as motility, differentiation, secretion, neurotransmission, and cell division. G proteins consist of three subunits organized as a Galpha monomer associated with a Gbetagamma heterodimer. Structural studies have shown that Galpha subunits are constituted by two domains: a Ras-like domain, also called the GTPase domain (GTPaseD), and an helical domain (HD), which is unique to heterotrimeric G-proteins. The HD display significantly higher primary structure diversity than the GTPaseD. Regardless of this diversity, there are small regions of the HD which show high degree of identity with residues that are 100% conserved. One of such regions is the alpha helixD-alpha helixE loop (alphaD-alphaE) in the HD, which contains the consensus aminoacid sequence R*-[RSA]-[RSAN]-E*-[YF]-[QH]-L in all mammalian Galpha subunits. Interestingly, the highly conserved arginine (R*) and glutamic acid (E*) residues form a salt bridge that stabilizes the alphaD-alphaE loop, that is localized in the top of the cleft formed between the GTPaseD and HD. Because the guanine nucleotide binding site is deeply buried in this cleft and those interdomain interactions are playing an important role in regulating the basal GDP/GTP nucleotide exchange rate of Galpha subunits, we studied the role of these highly conserved R and E residues in Galpha function. In the present study, we mutated the human Gsalpha R165 and E168 residues to alanine (A), thus generating the R165--> A, E168--> A, and R165/E168--> A mutants. We expressed these human Gsalpha (hGsalpha) mutants in bacteria as histidine tagged proteins, purified them by niquel-agarose chromatography and studied their nucleotide exchange properties. We show that the double R165/E168--> A mutant exhibited a fivefold increased GTP binding kinetics, a higher GDP dissociation rate, and an augmented capacity to activate adenylyl cyclase. Structure analysis showed that disruption of the salt bridge between R165 and E168 by the introduced mutations, caused important structural changes in the HD at the alphaD-alphaE loop (residues 160-175) and in the GTPaseD at a region required for Gsalpha activation by the receptor (residues 308-315). In addition, other two GTPaseD regions that surround the GTP binding site were also affected.

    Journal of cellular biochemistry 2004;93;2;409-17

  • The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

    Gerhard DS, Wagner L, Feingold EA, Shenmen CM, Grouse LH, Schuler G, Klein SL, Old S, Rasooly R, Good P, Guyer M, Peck AM, Derge JG, Lipman D, Collins FS, Jang W, Sherry S, Feolo M, Misquitta L, Lee E, Rotmistrovsky K, Greenhut SF, Schaefer CF, Buetow K, Bonner TI, Haussler D, Kent J, Kiekhaus M, Furey T, Brent M, Prange C, Schreiber K, Shapiro N, Bhat NK, Hopkins RF, Hsie F, Driscoll T, Soares MB, Casavant TL, Scheetz TE, Brown-stein MJ, Usdin TB, Toshiyuki S, Carninci P, Piao Y, Dudekula DB, Ko MS, Kawakami K, Suzuki Y, Sugano S, Gruber CE, Smith MR, Simmons B, Moore T, Waterman R, Johnson SL, Ruan Y, Wei CL, Mathavan S, Gunaratne PH, Wu J, Garcia AM, Hulyk SW, Fuh E, Yuan Y, Sneed A, Kowis C, Hodgson A, Muzny DM, McPherson J, Gibbs RA, Fahey J, Helton E, Ketteman M, Madan A, Rodrigues S, Sanchez A, Whiting M, Madari A, Young AC, Wetherby KD, Granite SJ, Kwong PN, Brinkley CP, Pearson RL, Bouffard GG, Blakesly RW, Green ED, Dickson MC, Rodriguez AC, Grimwood J, Schmutz J, Myers RM, Butterfield YS, Griffith M, Griffith OL, Krzywinski MI, Liao N, Morin R, Morrin R, Palmquist D, Petrescu AS, Skalska U, Smailus DE, Stott JM, Schnerch A, Schein JE, Jones SJ, Holt RA, Baross A, Marra MA, Clifton S, Makowski KA, Bosak S, Malek J and MGC Project Team

    The National Institutes of Health's Mammalian Gene Collection (MGC) project was designed to generate and sequence a publicly accessible cDNA resource containing a complete open reading frame (ORF) for every human and mouse gene. The project initially used a random strategy to select clones from a large number of cDNA libraries from diverse tissues. Candidate clones were chosen based on 5'-EST sequences, and then fully sequenced to high accuracy and analyzed by algorithms developed for this project. Currently, more than 11,000 human and 10,000 mouse genes are represented in MGC by at least one clone with a full ORF. The random selection approach is now reaching a saturation point, and a transition to protocols targeted at the missing transcripts is now required to complete the mouse and human collections. Comparison of the sequence of the MGC clones to reference genome sequences reveals that most cDNA clones are of very high sequence quality, although it is likely that some cDNAs may carry missense variants as a consequence of experimental artifact, such as PCR, cloning, or reverse transcriptase errors. Recently, a rat cDNA component was added to the project, and ongoing frog (Xenopus) and zebrafish (Danio) cDNA projects were expanded to take advantage of the high-throughput MGC pipeline.

    Funded by: PHS HHS: N01-C0-12400

    Genome research 2004;14;10B;2121-7

  • T393C polymorphism of GNAS1 associated with the autonomic nervous system in young, healthy Japanese subjects.

    Yasuda K, Matsunaga T, Moritani T, Nishikino M, Gu N, Yoshinaga M, Nagasumi K, Yamamura T, Aoki N and Tsuda K

    Department of Endocrinology, Metabolism and Diabetes Mellitus, Kinki University School of Medicine, Osaka, Japan.

    1. T393C polymorphism of the gene encoding the Gs-protein alpha-subunit (GNAS1) has been reported recently to be associated with hypertension in which dysfunctions of the autonomic nervous system (ANS) are closely involved. In the present study, the association of this polymorphism with ANS activity was investigated in young, healthy Japanese males. 2. Four hundred and one subjects were genotyped for the T393C polymorphism of GNAS1 by polymerase chain reaction-restriction fragment length polymorphism. Autonomic nervous system activity during supine rest and when standing was assessed in 137 subjects by electrocardiogram R-R interval power spectral analysis. 3. One hundred and fifty-four subjects (38.4%) were homozygous for the T allele (TT), 188 (46.9%) were heterozygous (TC) and 59 (14.7%) were homozygous for the C allele (CC). There were no significant differences as to genotype among the clinical characteristics investigated. In power spectral analysis of heart rate variability, the high-frequency component and parasympathetic nervous system (PNS) index during supine rest were significantly lower in TT and TC carriers than in CC carriers. Furthermore, the increase in heart rate and the responsiveness of sympathetic nervous system index and PNS index to postural change from supine rest to standing were significantly lower in TT and TC carriers than in CC carriers. 4. These observations suggest that the GNAS1 T393C polymorphism is associated with ANS activity in youth, so that it may be useful as a genetic marker for future pathogenesis of hypertension. Follow-up studies are necessary to clarify the prevalence rates of hypertension among 393T allele carriers in the present study.

    Clinical and experimental pharmacology & physiology 2004;31;9;597-601

  • A dominant negative Galphas mutant that prevents thyroid-stimulating hormone receptor activation of cAMP production and inositol 1,4,5-trisphosphate turnover: competition by different G proteins for activation by a common receptor.

    Cleator JH, Ravenell R, Kurtz DT and Hildebrandt JD

    Department of Ph 109b armacology, Medical University of South Carolina, Charleston, SC 29425, USA.

    A Ser to Asn mutation at position 54 of the alpha subunit of G(s) (designated N54-alpha(s)) was characterized after transient expression of it with various components of the receptor-adenylyl cyclase pathway in COS-1, COS-7, and HEK 293 cells. Previous studies of the N54-alpha(s) mutant revealed that it has a conditional dominant negative phenotype that prevents hormone-stimulated increases in cAMP without interfering with the regulation of basal cAMP levels (Cleator, J. H., Mehta, N. D., Kurtz, D. K., Hildebrandt, J. D. (1999) FEBS Lett. 243, 205-208). Experiments reported here were conducted to localize the mechanism of the dominant negative effect of the mutant. Competition studies conducted with activated alpha(s)* (Q212L) showed that the N54 mutant did not work down-stream by blocking the interaction of endogenous alpha(s) with adenylyl cyclase. The co-expression of wild type or N54-alpha(s) along with the thyroid-stimulating hormone (TSH) receptor and adenylyl cycla 5a8 se isotypes differing with respect to betagamma stimulation (AC II or AC III) revealed that the phenotype of the mutant is not dependent upon the presence of adenylyl cyclase isoforms regulated by betagamma. These studies ruled out a downstream site of action of the mutant. To investigate an upstream site of action, N54-alpha(s) was co-expressed with either the TSH receptor that activates both alpha(s) and alpha(q) or with the alpha(1B)-adrenergic receptor that activates only alpha(q). N54-alpha(s) failed to inhibit alpha(1B)-adrenergic receptor stimulation of inositol 1,4,5-trisphosphate production but did inhibit TSH stimulation of inositol 1,4,5-trisphosphate. These results show that G(s) and G(q) compete for activation by the TSH receptor. They also indicate that the N54 protein has a dominant negative phenotype by blocking upstream receptor interactions with normal G proteins. This phenotype is different from that seen in analogous mutants of other G protein alpha subunits and suggests that either regulation or protein-protein interactions differ among G protein alpha subunits.

    Funded by: NIDDK NIH HHS: DK 37219

    The Journal of biological chemistry 2004;279;35;36601-7

  • XLalphas, the extra-long form of the alpha-subunit of the Gs G protein, is significantly longer than suspected, and so is its companion Alex.

    Abramowitz J, Grenet D, Birnbaumer M, Torres HN and Birnbaumer L

    Transmembrane Signal Transduction Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA.

    Because of the use of alternate exons 1, mammals express two distinct forms of Gsalpha-subunits: the canonical 394-aa Gsalpha present in all tissues and a 700+-aa extra-long alphas (XLalphas) expressed in a more restricted manner. Both subunits transduce receptor signals into stimulation of adenylyl cyclase. The XL exon encodes the XL domain of XLalphas and, in a parallel ORF, a protein called Alex. Alex interacts with the XL domain of XLalphas and inhibits its adenylyl cyclase-stimulating function. In mice, rats, and humans, the XL exon is thought to contribute 422.3, 367.3, and 551.3 codons and to encode Alex proteins of 390, 357, and 561 aa, respectively. We report here that the XL exon is longer than presumed and contributes in mice, rats, and humans, respectively, an additional 364, 430, and 139 codons to XLalphas. We called the N-terminally extended XLalphas extra-extra-long Gsalpha, or XXLalphas. Alex is likewise longer. Its ORF also remains open in the 5' direction for approximately 2,000 nt, giving rise to Alex-extended, or AlexX. RT-PCR of murine total brain RNA shows that the entire XXL domain is encoded in a single exon. Furthermore, we discovered two truncated forms of XXLalphas, XXLb1 and XXLb2, in which, because of alternative splicing, the Gsalpha domain is replaced by different sequences. XXLb proteins are likely to be found as stable dimers with AlexX. The N-terminally longer proteins may play regulatory roles.

    Proceedings of the National Academy of Sciences of the United States of America 2004;101;22;8366-71

  • Genetic variants of the extra-large stimulatory Gs protein alpha-subunit and risk of thrombotic and haemorrhagic disorders.

    González-Conejero R, Corral J, Guerrero JA, Iniesta JA, Rivera J and de Arriba F

    Department of Medicine, University of Murcia, Murcia, Spain. rocio.gonzalez@carm.es

    A polymorphism of the gene encoding the extra-large stimulatory G-protein alpha-subunit (XLalphas), originally identified in three patients with a bleeding tendency, involved a 36-bp insertion and two missense changes. A paternally-inherited insertion displayed a moderate platelet Gsalpha over-expression, which lead to platelet hypo-reactivity. These data prompted us to investigate the genetic, functional and clinical relevance of this polymorphism in the Mediterranean population. We included 414 healthy subjects and three case/control studies: 263 consecutive patients with a first episode of primary intracerebral haemorrhage, 195 patients with deep venous thrombosis, and 104 patients with cerebrovascular disease. Controls were selected by approximating criteria to match selected risk factors to patients. Moreover, we performed studies of platelet function. We developed a simple method to determine the methylated allele, by digestion of genomic DNA with Sma I before polymerase chain reaction amplification. We identified two new rare variants, resulting from the loss of repeat units 7 and 5. The AB genotype was present in 3.6% of healthy population and the prevalence of the B allele was similar among cases and controls. Accordingly, the non-methylated B allele did not modify either the expression of platelet Gsalpha or the platelet response to Gs-agonists. Thus, our study suggests a minor functional role of XLalphas polymorphism in thrombotic or in haemorrhagic disorders.

    British journal of haematology 2004;125;5;621-8

  • Parental origin of Gsalpha mutations in the McCune-Albright syndrome and in isolated endocrine tumors.

    Mantovani G, Bondioni S, Lania AG, Corbetta S, de Sanctis L, Cappa M, Di Battista E, Chanson P, Beck-Peccoz P and Spada A

    Institute of Endocrine Sciences, University of Milan, Ospedale Maggiore IRCCS, 20122 Milan, Italy.

    Activating mutations of the Gsalpha gene are detected in different endocrine tumors, such as GH-secreting adenomas and toxic thyroid adenomas, and in hyperfunctioning glands from patients with McCune-Albright syndrome (MAS). There is increasing evidence that the Gsalpha gene is subjected to imprinting control and that Gsalpha imprinting plays a key role in the pathogenesis of different human diseases. The aim of this study was to investigate the presence of a parent specificity of Gsalpha mutations in 10 patients affected with MAS and 12 isolated tumors (10 GH-secreting adenomas, one toxic thyroid adenoma, and one hyperfunctioning adrenal adenoma). The parental origin of Gsalpha mutations was assessed by evaluating NESP55 and exon 1A transcripts, which are monoallelically expressed from the maternal and paternal alleles, respectively. By this approach, we demonstrated that in isolated GH-secreting adenomas, as well as in MAS patients with acromegaly, Gsalpha mutations were on the maternal allele. By contrast, the involvement of other endocrine organs in MAS patients was not associated with a particular parent specificity, as precocious puberty and hyperthyroidism were present in patients with mutations on either the maternal or the paternal allele. Moreover, isolated hyperfunctioning thyroid and adrenal adenomas displayed the mutation on the maternal and paternal alleles, respectively. These data confirm the importance of Gsalpha imprinting in the pituitary gland and point out the high degree of tissue specificity of this phenomenon.

    The Journal of clinical endocrinology and metabolism 2004;89;6;3007-9

  • Activating Gsalpha mutations: analysis of 113 patients with signs of McCune-Albright syndrome--a European Collaborative Study.

    Lumbroso S, Paris F, Sultan C and European Collaborative Study

    Service d'Hormonologie, Hôpital Lapeyronie, Centre Hospitalier Universitaire (CHU) de Montpellier and Institut National de la Santé et de la Recherche Médicale, Montpellier, France 34295.

    McCune-Albright syndrome (MAS) is a sporadic disorder characterized by the classic triad of polyostotic fibrous dysplasia, café-au-lait skin pigmentation, and peripheral precocious puberty. It is due to postzygotic activating mutations of arginine 201 in the guanine-nucleotide-binding protein (G protein) alpha-subunit (Gsalpha), leading to a mosaic distribution of cells bearing constitutively active adenylate cyclase. MAS is heterogeneous: beyond the classic triad, a number of atypical or partial presentations have been reported. We present here the results of a systematic search for Gsalpha mutations in patients presenting with at least one of the signs of MAS, using a PCR-based sensitive method. We studied 113 patients (98 girls and 15 boys), 24% presenting the classic triad, 33% with two signs, and 40% with only one classic sign. Overall, the mutation was identified in 43% of the patients. When an affected tissue was available, the mutation was found in more than 90% of the patients, whatever the number of signs. Skin was a noteworthy exception because only three of the 11 skin samples were positive. The mutation was detected in 46% of blood samples in patients presenting the classic triad, whereas this figure fell to 21% and 8% in patients with two and one sign, respectively. Our results highlight the frequency of partial forms of MAS and the usefulness of sensitive techniques to confirm the diagnosis at the molecular level. It should be emphasized that we found the mutation in 33% of the 39 cases of isolated peripheral precocious puberty. This study has further widened the definition of MAS. Affections as clinically different as monostotic fibrous dysplasia, isolated peripheral precocious puberty, neonatal liver cholestasis, and the classic MAS all appear to be components of a wide spectrum of diseases based on the same molecular defect.

    The Journal of clinical endocrinology and metabolism 2004;89;5;2107-13

  • Long-term agonist stimulation of IP prostanoid receptor depletes the cognate G(s)alpha protein in membrane domains but does not change the receptor level.

    Moravcová Z, Rudajev, Stöhr J, Novotný J, Cerný J, Parenti M and Milligan G

    Department of Physiology, Faculty of Natural Sciences, Charles University, Vinicna 7, 12000 Prague 2, Czech Republic.

    Iloprost (IP) stimulation (1 microM, 2 h) of Flag-epitope-tagged human IP prostanoid receptor (FhIPR) expressed in HEK293 cells resulted in specific decrease of endogenous G(s)alpha protein in detergent-insensitive, caveolin-enriched, membrane domains (DIMs). Receptor protein FhIPR, caveolin, G(i)alpha and GPI-linked, domain markers CD55 and CD59 were unchanged. The same result was obtained in HEK293 cells expressing FhIPR-G(s)alpha fusion protein. The endogenous G(s)alpha decreased, but the level of Flag-hIPR-G(s)alpha protein did not change. The specific depletion of domain-bound pool of G(s)alpha as consequence of iloprost stimulation was also demonstrated in membrane domains prepared according to alkaline treatment plus sonication protocol (detergent-free procedure of Song et al.). Our data further indicated that in control, quiescent cells only a very small amount of IP prostanoid receptor was present in DIMs together with large amount of its cognate G(s)alpha protein. Expressed in quantitative terms, DIMs contained 30-40% of the total cellular amount of G proteins whereas the content of IP prostanoid receptors was 1-3%. The dominant portion (>95%) of FhIPR as well as FhIPR-G(s)alpha was localised in high-density area of the gradient containing detergent-solubilised proteins. FhIPR and FhIPR-G(s)alpha distribution was similar to that of transmembrane plasma membrane (PM) markers (CD147, MHCI, CD29, Tapa1, the alpha subunit of Na,K-ATPase, transmembrane form of CD58 and CD44). All these proteins are known to be fully solubilised by detergent and thus unable to float in density gradient. Our data indicate that (i) long-term agonist stimulation of IP prostanoid receptor is associated with preferential decrease of its cognate G protein G(s)alpha from membrane domains; receptor level is unchanged. (ii) Very small fraction (1-3%) of total cellular amount of receptors is recovered in DIMs together with roughly 40% of G proteins. These data suggest a "supra-stoichiometric" arrangement of G proteins and corresponding receptors in DIMs.

    Biochimica et biophysica acta 2004;1691;1;51-65

  • Brachydactyly in 14 genetically characterized pseudohypoparathyroidism type Ia patients.

    de Sanctis L, Vai S, Andreo MR, Romagnolo D, Silvestro L and de Sanctis C

    Department of Pediatric Sciences, University of Torino, Torino, Italy. ldesancct@pediatria.unito.it

    Brachydactyly, classically described as shortening of III, IV, and V metacarpals and I distal phalanx, is the typical and most specific sign of Albright's hereditary osteodystrophy, a peculiar phenotype reported in subjects with pseudohypoparathyroidism type Ia (PHP-Ia) caused by mutations in the GNAS gene, which encodes for the alpha-subunit of the stimulatory G protein (Gsalpha). It has been reported in 70% of PHP subjects from routine radiological examinations, but there are no specific data for hand alterations in genetically characterized PHP-Ia subjects. We evaluated the metacarpophalangeal pattern profile in 14 GNAS-mutated PHP-Ia subjects and determined the prevalence and patterns of left hand bone shortening. To search for genotype/phenotype correlations, we compared metacarpophalangeal pattern profiles in subjects with identical mutations. Shortening below -2 SD score (SDS) was present in at least one bone in each subject, with a prevalence of 100%; however, great variability existed between subjects and between hand bone segments. Between subjects, shortening ranged from -2 to -10.4 SDS and involved 1-19 hand bones (5.3-100%). Between segments, III-IV metacarpals were the most compromised (-10.4 and -10.0 SDS, respectively); V metacarpals and I-IV distal phalanges were the most frequently shortened (85.7%). Overall, bone length median values revealed shortening below -2 SDS in all metacarpals and all distal phalanges, i.e. brachymetacarpia and brachytelephalangy, that cluster together. These segments were shortened in 64.3-85.7% of patients, significantly differing from proximal and middle phalanges, which were shortened in 21.4-50%. Even if these hand alterations were a constant and typical finding in our PHP-Ia population, cluster analysis in subjects with the same genotypes did not generally show a genotype/phenotype correlation. Variability between subjects may be the result of complex interactions between GNAS defects and other genetic or epigenetic factors. In conclusion, hand shortening analysis in 14 genetically characterized patients showed typical brachymetacarpia and brachytelephalangy. Further studies in PHP-Ia subjects without GNAS mutations and in other brachydactyly syndromes will determine whether the pattern described is also specific.

    The Journal of clinical endocrinology and metabolism 2004;89;4;1650-5

  • Impairment of G(salpha) function in human brain cortex of Alzheimer's disease: comparison with normal aging.

    Hashimoto E, Ozawa H, Saito T, Gsell W, Takahata N, Riederer P and Frölich L

    Clinical Neurochemistry and NPF Center of Excellence Research Labs., Department of Psychiatry, University of Würzburg, Germany.

    We examined the quantity and quality of G proteins in membrane preparations of post-mortem human brain, i.e. in parietal, temporal and occipital cortical regions, from normal subjects over age (17-89 years old) and with Alzheimer's disease (AD) in comparison with aged-matched controls. In normal aging, the immunoreactivities determined of G(ialpha), G(qalpha) and G(beta) were inversely correlated with age. The function of G proteins was examined by photoaffinity GTP analogue [azidoanilido GTP (AAGTP)] labelling. AAGTP labelling to G(salpha) and G(i/oalpha), and the ratio of G(salpha) to G(i/oalpha) AAGTP labelling showed no age-dependent changes. In AD compared to age-matched controls, there were no significant differences in the levels of G(sHalpha), G(sLalpha), G(ialpha), G(oalpha), G(qalpha) and G(beta) subunits. Functional effects of G proteins, however, as measured by AAGTP labelling to G(salpha), but not to G(i/oalpha), was significantly decreased in AD compared to controls in the parietal and temporal cortex, but not in the occipital cortex. These results suggest that the disturbances of post-receptor trans-membrane signalling in AD can be attributed to functional changes of G(salpha), and these are independent of alterations in the level for those proteins in normal aging.

    Journal of neural transmission (Vienna, Austria : 1996) 2004;111;3;311-22

  • McCune-Albright syndrome associated with pituitary microadenoma: patient report.

    Chen CJ, Liu JY, Cheng SN, Chang FW and Yuh YS

    Department of Pediatrics, Tri-service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China.

    McCune-Albright syndrome (MAS) is a rare disorder characterized by the classic triad of precocious puberty, polyostotic fibrous dysplasia and café-au-lait spots. Additional endocrine abnormalities may also be present, including hyperthyroidism, growth hormone excess and hyperprolactinemia. The most commonly encountered endocrine dysfunction is gonadal hyperfunction. Gonadotropin-independent precocious puberty is typically the initial manifestation of MAS in girls. Ovarian cysts may be detected on pelvic ultrasound. Our patient was also found to have pituitary microadenoma, evidenced by dynamic magnetic resonance imaging.

    Journal of pediatric endocrinology & metabolism : JPEM 2004;17;3;365-9

  • Sensorimotor gating deficits in transgenic mice expressing a constitutively active form of Gs alpha.

    Gould TJ, Bizily SP, Tokarczyk J, Kelly MP, Siegel SJ, Kanes SJ and Abel T

    Department of Psychology, Temple University, Weiss Hall, Philadelphia, PA, USA.

    Schizophrenia is a complex disorder characterized by wide-ranging cognitive impairments, including deficits in learning as well as sensory gating. The causes of schizophrenia are unknown, but alterations in intracellular G-protein signaling pathways are among the molecular changes documented in patients with schizophrenia. Using the CaMKIIalpha promoter to drive expression in neurons within the forebrain, we have developed transgenic mice that express a constitutively active form of G(s)alpha (G(s)alpha(*)), the G protein that couples receptors such as the D(1) and D(5) dopamine receptors to adenylyl cyclase. We have also generated mice in which the CaMKIIalpha promoter drives expression of a dominant-negative form of protein kinase A, R(AB). Here, we examine startle responses and prepulse inhibition of the startle reflex (PPI) in these G(s)alpha(*) and R(AB) transgenic mice. G(s)alpha(*) transgenic mice exhibited selective deficits in PPI, without exhibiting alterations in the startle response, whereas no deficit in startle or PPI was found in the R(AB) transgenic mice. Thus, overstimulation of the cAMP/PKA pathway disrupts PPI, but the cAMP/PKA pathway may not be essential for sensorimotor gating. G(s)alpha(*) transgenic mice may provide an animal model of certain endophenotypes of schizophrenia, because of the similarities between them and patients with schizophrenia in G-protein function, hippocampus-dependent learning, and sensorimotor gating.

    Funded by: NIA NIH HHS: R01 AG018199, R01 AG018199-02, R01 AG18199; NICHD NIH HHS: HD26979, P30 HD026979; NIMH NIH HHS: K08 MH067091, K08 MH067091-02, P50 MH064045, P50 MH064045-01, P50 MH6404501, R01 MH060244, R01 MH060244-02, R01 MH60244, T32 MH019112, T32 MH019112-10

    Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 2004;29;3;494-501

  • Complete sequencing and characterization of 21,243 full-length human cDNAs.

    Ota T, Suzuki Y, Nishikawa T, Otsuki T, Sugiyama T, Irie R, Wakamatsu A, Hayashi K, Sato H, Nagai K, Kimura K, Makita H, Sekine M, Obayashi M, Nishi T, Shibahara T, Tanaka T, Ishii S, Yamamoto J, Saito K, Kawai Y, Isono Y, Nakamura Y, Nagahari K, Murakami K, Yasuda T, Iwayanagi T, Wagatsuma M, Shiratori A, Sudo H, Hosoiri T, Kaku Y, Kodaira H, Kondo H, Sugawara M, Takahashi M, Kanda K, Yokoi T, Furuya T, Kikkawa E, Omura Y, Abe K, Kamihara K, Katsuta N, Sato K, Tanikawa M, Yamazaki M, Ninomiya K, Ishibashi T, Yamashita H, Murakawa K, Fujimori K, Tanai H, Kimata M, Watanabe M, Hiraoka S, Chiba Y, Ishida S, Ono Y, Takiguchi S, Watanabe S, Yosida M, Hotuta T, Kusano J, Kanehori K, Takahashi-Fujii A, Hara H, Tanase TO, Nomura Y, Togiya S, Komai F, Hara R, Takeuchi K, Arita M, Imose N, Musashino K, Yuuki H, Oshima A, Sasaki N, Aotsuka S, Yoshikawa Y, Matsunawa H, Ichihara T, Shiohata N, Sano S, Moriya S, Momiyama H, Satoh N, Takami S, Terashima Y, Suzuki O, Nakagawa S, Senoh A, Mizoguchi H, Goto Y, Shimizu F, Wakebe H, Hishigaki H, Watanabe T, Sugiyama A, Takemoto M, Kawakami B, Yamazaki M, Watanabe K, Kumagai A, Itakura S, Fukuzumi Y, Fujimori Y, Komiyama M, Tashiro H, Tanigami A, Fujiwara T, Ono T, Yamada K, Fujii Y, Ozaki K, Hirao M, Ohmori Y, Kawabata A, Hikiji T, Kobatake N, Inagaki H, Ikema Y, Okamoto S, Okitani R, Kawakami T, Noguchi S, Itoh T, Shigeta K, Senba T, Matsumura K, Nakajima Y, Mizuno T, Morinaga M, Sasaki M, Togashi T, Oyama M, Hata H, Watanabe M, Komatsu T, Mizushima-Sugano J, Satoh T, Shirai Y, Takahashi Y, Nakagawa K, Okumura K, Nagase T, Nomura N, Kikuchi H, Masuho Y, Yamashita R, Nakai K, Yada T, Nakamura Y, Ohara O, Isogai T and Sugano S

    Helix Research Institute, 1532-3 Yana, Kisarazu, Chiba 292-0812, Japan.

    As a base for human transcriptome and functional genomics, we created the "full-length long Japan" (FLJ) collection of sequenced human cDNAs. We determined the entire sequence of 21,243 selected clones and found that 14,490 cDNAs (10,897 clusters) were unique to the FLJ collection. About half of them (5,416) seemed to be protein-coding. Of those, 1,999 clusters had not been predicted by computational methods. The distribution of GC content of nonpredicted cDNAs had a peak at approximately 58% compared with a peak at approximately 42%for predicted cDNAs. Thus, there seems to be a slight bias against GC-rich transcripts in current gene prediction procedures. The rest of the cDNAs unique to the FLJ collection (5,481) contained no obvious open reading frames (ORFs) and thus are candidate noncoding RNAs. About one-fourth of them (1,378) showed a clear pattern of splicing. The distribution of GC content of noncoding cDNAs was narrow and had a peak at approximately 42%, relatively low compared with that of protein-coding cDNAs.

    Nature genetics 2004;36;1;40-5

  • Autosomal dominant pseudohypoparathyroidism type Ib is associated with a heterozygous microdeletion that likely disrupts a putative imprinting control element of GNAS.

    Bastepe M, Fröhlich LF, Hendy GN, Indridason OS, Josse RG, Koshiyama H, Körkkö J, Nakamoto JM, Rosenbloom AL, Slyper AH, Sugimoto T, Tsatsoulis A, Crawford JD and Jüppner H

    Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA.

    Patients with pseudohypoparathyroidism type Ib (PHP-Ib) have hypocalcemia and hyperphosphatemia due to renal parathyroid hormone (PTH) resistance, but lack physical features of Albright hereditary osteodystrophy. PHP-Ib is thus distinct from PHP-Ia, which is caused by mutations in the GNAS exons encoding the G protein alpha subunit. However, an imprinted autosomal dominant form of PHP-Ib (AD-PHP-Ib) has been mapped to a region of chromosome 20q13.3 containing GNAS. Furthermore, loss of methylation at a differentially methylated region (DMR) of this locus, exon A/B, has been observed thus far in all investigated sporadic PHP-Ib cases and the affected members of multiple AD-PHP-Ib kindreds. We now report that affected members and obligate gene carriers of 12 unrelated AD-PHP-Ib kindreds and four apparently sporadic PHP-Ib patients, but not healthy controls, have a heterozygous approximately 3-kb microdeletion located approximately 220 kb centromeric of GNAS exon A/B. The deleted region, which is flanked by two direct repeats, includes three exons of STX16, the gene encoding syntaxin-16, for which no evidence of imprinting could be found. Affected individuals carrying the microdeletion show loss of exon A/B methylation but no epigenetic abnormalities at other GNAS DMRs. We therefore postulate that this microdeletion disrupts a putative cis-acting element required for methylation at exon A/B, and that this genetic defect underlies the renal PTH resistance in AD-PHP-Ib.

    Funded by: NIDDK NIH HHS: K01 DK062973, KO1 DK-062973-01A1; PHS HHS: R01 46718-10

    The Journal of clinical investigation 2003;112;8;1255-63

  • Erythrocyte G protein-coupled receptor signaling in malarial infection.

    Harrison T, Samuel BU, Akompong T, Hamm H, Mohandas N, Lomasney JW and Haldar K

    Department of Pathology, Feinberg School of Medicine, Northwestern University, 303 Chicago Avenue, Chicago, IL 60611, USA.

    Erythrocytic mechanisms involved in malarial infection are poorly understood. We have found that signaling via the erythrocyte beta2-adrenergic receptor and heterotrimeric guanine nucleotide-binding protein (Galphas) regulated the entry of the human malaria parasite Plasmodium falciparum. Agonists that stimulate cyclic adenosine 3',5'-monophosphate production led to an increase in malarial infection that could be blocked by specific receptor antagonists. Moreover, peptides designed to inhibit Galphas protein function reduced parasitemia in P. falciparum cultures in vitro, and beta-antagonists reduced parasitemia of P. berghei infections in an in vivo mouse model. Thus, signaling via the erythrocyte beta2-adrenergic receptor and Galphas may regulate malarial infection across parasite species.

    Funded by: NEI NIH HHS: EY06062, EY10291; NHLBI NIH HHS: HL03961, HL55591, HL69630; NIAID NIH HHS: AI39071

    Science (New York, N.Y.) 2003;301;5640;1734-6

  • The stimulatory G protein alpha-subunit Gs alpha is imprinted in human thyroid glands: implications for thyroid function in pseudohypoparathyroidism types 1A and 1B.

    Liu J, Erlichman B and Weinstein LS

    Metabolic Diseases Branch, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

    The stimulatory G protein alpha-subunit G(s)alpha couples receptors to adenylyl cyclase and is required for hormone-stimulated cAMP generation. In Albright hereditary osteodystrophy, heterozygous G(s)alpha null mutations only lead to PTH, TSH, and gonadotropin resistance when inherited maternally [pseudohypoparathyroidism type 1A; (PHP1A)]. Maternal-specific expression of G(s)alpha in specific hormone targets could explain this observation. Using hot-stop PCR analysis on total RNA from six normal human thyroid specimens, we showed that the majority of the G(s)alpha mRNA (72 +/- 3%) was derived from the maternal allele. This is consistent with the presence of TSH resistance in patients with maternal G(s)alpha null mutations (PHP1A) and the absence of TSH resistance in patients with paternal G(s)alpha mutations (pseudopseudohypoparathyroidism). Patients with PTH resistance in the absence of Albright hereditary osteodystrophy (PHP1B) have an imprinting defect of the G(s)alpha gene resulting in both alleles having a paternal epigenotype, which would lead to a more moderate level of thyroid-specific G(s)alpha deficiency. We found evidence of borderline TSH resistance in 10 of 22 PHP1B patients. This study provides further evidence for tissue-specific imprinting of G(s)alpha in humans and provides a potential mechanism for mild to moderate TSH resistance in PHP1A and borderline resistance in some patients with PHP1B.

    The Journal of clinical endocrinology and metabolism 2003;88;9;4336-41

  • Growth hormone-releasing hormone resistance in pseudohypoparathyroidism type ia: new evidence for imprinting of the Gs alpha gene.

    Mantovani G, Maghnie M, Weber G, De Menis E, Brunelli V, Cappa M, Loli P, Beck-Peccoz P and Spada A

    Institute of Endocrine Sciences, University of Milan, Ospedale Maggiore Instituto di Ricovero e Cura a Carattere Scientifico (IRCCS), 20122 Milan, Italy.

    Heterozygous inactivating mutations in the Gs alpha gene cause Albright's hereditary osteodystrophy. Consistent with the observation that only maternally inherited mutations lead to resistance to hormone action [pseudohypoparathyroidism type Ia (PHP Ia)], recent studies provided evidence for a predominant maternal origin of Gs alpha transcripts in endocrine organs, such as thyroid, gonad, and pituitary. The aim of this study was to investigate the presence of pituitary resistance to hypothalamic hormones acting via Gs alpha-coupled receptors in patients with PHP Ia. Six of nine patients showed an impaired GH responsiveness to GHRH plus arginine, consistent with a complete GH deficiency (GH peak from 2.6-8.6 microg/liter, normal > 16.5), and partial (GH peak 13.9 and 13.6 microg/liter) and normal responses were found in two and one patient, respectively. Accordingly, IGF-I levels were below and in the low-normal range in seven and two patients. All patients had a normal cortisol response to 1 microg ACTH test, suggesting a normal corticotroph function that was confirmed by a normal ACTH and cortisol response to CRH test in three patients. In conclusion, we report that in addition to PTH and TSH resistance, patients with PHP Ia display variable degrees of GHRH resistance, consistent with Gs alpha imprinting in human pituitary.

    The Journal of clinical endocrinology and metabolism 2003;88;9;4070-4

  • Osteoclastogenesis in fibrous dysplasia of bone: in situ and in vitro analysis of IL-6 expression.

    Riminucci M, Kuznetsov SA, Cherman N, Corsi A, Bianco P and Gehron Robey P

    Dipartimento di Medicina Sperimentale, Università dell' Aquila, L' Aquila 67100, Italy.

    Fibrous dysplasia of bone (FD) is caused by somatic mutations of the GNAS1 gene, which lead to constitutive activation of adenylyl cyclase and overproduction of cAMP in osteogenic cells. Previous in vitro studies using nonclonal, heterogeneous strains of FD-derived cells suggested that IL-6 might play a critical role in promoting excess osteoclastogenesis in FD. In this study, we investigated IL-6 expression in FD in situ and its relationship to the actual patterns of osteoclastogenesis within the abnormal tissue. We found that osteoclastogenesis is not spatially restricted to bone surfaces in FD but occurs to a large extent ectopicly in the fibrous tissue, where stromal cells diffusely express IL-6 mRNA and exhibit a characteristic cell morphology. We also observed specific expression of IL-6 mRNA in a proportion of osteoclasts, suggesting that an autocrine/paracrine loop may contribute to osteoclastogenesis in vivo in FD, as in some other bone diseases, including Paget's disease. We also generated homogeneous, clonally derived strains of wild-type and GNAS1-mutated stromal cells from the same individual, parent FD lesions. In this way, we could show that mutated stromal cells produce IL-6 at a basal magnitude and rate that are significantly higher than in the cognate wild-type cells. Conversely, wild-type cells respond to db-cAMP with a severalfold increase in magnitude and rate of IL-6 production, whereas mutant strains remain essentially unresponsive. Our data establish a direct link between GNAS1 mutations in stromal cells and IL-6 production but also define the complexity of the role of IL-6 in regulating osteoclastogenesis in FD in vivo. Here, patterns of osteoclastogenesis and bone resorption reflect not only the cell-autonomous effects of GNAS1 mutations in osteogenic cells (including IL-6 production) but also the local and systemic context to which non-osteogenic cells, local proportions of wild-type vs mutated cells, and systemic hormones contribute.

    Funded by: Telethon: E.1029

    Bone 2003;33;3;434-42

  • Thyroid carcinoma in the McCune-Albright syndrome: contributory role of activating Gs alpha mutations.

    Collins MT, Sarlis NJ, Merino MJ, Monroe J, Crawford SE, Krakoff JA, Guthrie LC, Bonat S, Robey PG and Shenker A

    Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-4320, USA. mc247k@nih.gov

    McCune-Albright syndrome (MAS) is defined by the triad of café-au-lait skin pigmentation, polyostotic fibrous dysplasia, and hyperfunctioning endocrinopathies, such as precocious puberty, hyperthyroidism, GH excess, and Cushing's syndrome. This disorder is caused by sporadic, postzygotic activating mutations in the GNAS1 gene, which codes for the G(s)alpha protein in the cAMP signaling cascade. Nodular and diffuse goiters (with and without hyperthyroidism), as well as benign thyroid nodules, have been reported in association with MAS. Herein we report two cases of thyroid carcinoma in patients with MAS. The first is a case of papillary thyroid cancer detected incidentally during a hemithyroidectomy for hyperthyroidism in a 14-yr-old girl. The second is one of a 41-yr-old woman with long-standing MAS and an enlarging thyroid nodule, which was diagnosed as a clear cell thyroid carcinoma, a rare variant of thyroid cancer. Molecular analysis revealed that foci of malignancy and adjacent areas of hyperplasia and some areas of normal thyroid harbored activating mutations of Arg(201) in the GNAS1 gene. These findings suggest that the infrequent development of thyroid carcinoma in MAS patients involves additional mutational or epigenetic events.

    Funded by: NCI NIH HHS: CA-78436

    The Journal of clinical endocrinology and metabolism 2003;88;9;4413-7

  • Discordance between genetic and epigenetic defects in pseudohypoparathyroidism type 1b revealed by inconsistent loss of maternal imprinting at GNAS1.

    Jan de Beur S, Ding C, Germain-Lee E, Cho J, Maret A and Levine MA

    Division of Endocrinology and Metabolism, Department of Medicine, and The Ilyssa Center for Molecular and Cellular Endocrinology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA. sjandebe@jhmi.edu

    Although the molecular basis of pseudohypoparathyroidism type 1b (PHP type 1b) remains unknown, a defect in imprinting at the GNAS1 locus has been suggested by the consistent finding of paternal-specific patterns of DNA methylation on maternally inherited GNAS1 alleles. To characterize the relationship between the genetic and epigenetic defects in PHP type 1b, we analyzed allelic expression and methylation of CpG islands within exon 1A of GNAS1 in patients with sporadic PHP type 1b and in affected and unaffected individuals from five multigenerational kindreds with PHP type 1b. All subjects with resistance to parathyroid hormone (PTH) showed loss of methylation of the exon 1A region on the maternal GNAS1 allele and/or biallelic expression of exon 1A-containing transcripts, consistent with an imprinting defect. Paternal transmission of the disease-associated haplotype was associated with normal patterns of GNAS1 methylation and PTH responsiveness. We found that affected and unaffected siblings in one kindred had inherited the same GNAS1 allele from their affected mother, evidence for dissociation between the genetic and epigenetic GNAS1 defects. The absence of the epigenetic defect in subjects who have inherited a defective maternal GNAS1 allele suggests that the genetic mutation may be incompletely penetrant, and it indicates that the epigenetic defect, not the genetic mutation, leads to renal resistance to PTH in PHP type 1b.

    Funded by: NCRR NIH HHS: M01 RR000052, M01 RR00052; NIDDK NIH HHS: DK34281, R01-DK46720, T32 DK007751, T32-DK07751

    American journal of human genetics 2003;73;2;314-22

  • NESP55, a novel chromogranin-like peptide, is expressed in endocrine tumours of the pancreas and adrenal medulla but not in ileal carcinoids.

    Jakobsen AM, Ahlman H, Kölby L, Abrahamsson J, Fischer-Colbrie R and Nilsson O

    Lundberg Laboratory for Cancer Research, Department of Pathology, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden. anne-marie.jakobsen@llcr.med.gu.se

    Neuroendocrine secretory protein 55, NESP55, is an acidic protein belonging to the chromogranin family. The distribution of NESP55 in human tumours is not known. The aim of the present study was to study the expression of NESP55 in human gastrointestinal, pancreatic and adrenal tumours. A total of 118 human endocrine and nonendocrine tumours were examined by immunocytochemistry, and compared to the expression of chromogranin A (CgA) in the same tumours. Pancreatic endocrine tumours (14 out of 25), pheochromocytomas (19 out of 19), and neuroblastomas (seven out of 14) expressed NESP55, with the same strong labelling pattern in both benign and malignant tumours. Expression of NESP55 in pancreatic endocrine tumours and pheochromocytomas was confirmed by Western and Northern blot analysis. Immunocytochemical analysis demonstrated no labelling in ileal carcinoids (zero out of 15), and adrenocortical adenomas (zero out of 15). The majority of gastrointestinal and pancreatic carcinomas were negative for NESP55, with focal staining observed in two out of 30 tumours. In contrast, CgA was present in all neuroendocrine tumours examined (25 out of 25 pancreatic endocrine tumours, 19 out of 19 pheochromocytomas, 14 out of 14 neuroblastomas and 15 out of 15 ileal carcinoids). Thus, the expression of NESP55 in endocrine tumours of the gastrointestinal tract, pancreas and adrenals differs from that of CgA. Neuroendocrine secretory protein 55 is found in a subset of neuroendocrine tumours showing differentiation towards adrenal chromaffin cells and pancreatic islets cells.

    British journal of cancer 2003;88;11;1746-54

  • Altered CTX-catalyzed and endogenous [32P]ADP-ribosylation of stimulatory G protein alphas isoforms in postmortem bipolar affective disorder temporal cortex.

    Andreopoulos S, Li PP, Siu KP, Kish SJ and Warsh JJ

    Laboratory of Cellular and Molecular Pathophysiology, Center for Addiction and Mental Health, Clarke Site, Toronto, Canada.

    Reports of elevated Gs alpha subunit (alpha(s)) immunolabeling and cAMP-mediated hyper-functionality in autopsied cerebral cortical brain regions from bipolar affective disorder (BD) patients suggest signal transduction abnormalities occur in this disorder. Because covalent modification of alpha(s) can affect its turnover and levels, we determined whether CTX-catalyzed and endogenous [(32)P] adenosine diphosphate (ADP)-ribosylation of alpha(s) isoforms are altered in temporal and occipital cortical regions, which show elevated alpha(s) levels in BD as compared to nonpsychiatric subjects. Reduced CTX-catalyzed [(32)P]ADP-ribosylated alpha(s-S) and endogenous [(32)P]ADP-ribosylation of a 39-kDa alpha(s)-like protein were found in BD temporal cortex compared to controls. These findings suggest that clearance of these alpha(s) isoforms through ADP-ribosylation may be decreased in BD temporal cortex. Although no differences were observed in mean levels of endogenous and CTX-catalyzed [(32)P]ADP-ribosylation of alpha(s-L) in BD temporal cortex, alpha(s-L) immunolabeling was elevated significantly and correlated inversely with the degree of endogenous [(32)P]ADP-ribosylation of this subunit. In addition, endogenous [(32)P]ADP-ribosylation of an exogenous substrate, myelin basic protein, 13f8 was similar in BD and comparison subject temporal cortex. Taken together, these observations suggest that elevations of alpha(s) in BD brain are more likely related to factors affecting the disposition or availability of alpha(s) to this posttranslational enzymatic modification.

    Journal of neuroscience research 2003;72;5;638-45

  • Association of the GNAS1 gene variant with hypertension is dependent on alcohol consumption.

    Chen Y, Nakura J, Jin JJ, Wu Z, Yamamoto M, Abe M, Tabara Y, Yamamoto Y, Igase M, Bo X, Kohara K and Miki T

    Department of Geriatric Medicine, School of Medicine, Ehime University, Ehime, Japan.

    The beta-adrenoceptor (beta-AR)-stimulatory guanine nucleotide-binding (Gs) protein system has been shown to play important roles in the cardiovascular system. The gene encoding the alpha-subunit of Gs proteins (GNAS1) is a candidate genetic determinant for hypertension. Because alcohol consumption is known to affect blood pressure partly through the beta-AR-Gs protein system, we examined the possible interaction between GNAS1 T393C polymorphism and drinking status in the association with hypertension in the present study. As a result, a non-significant but reasonable trend supporting the presence of an interaction was shown (p = 0.076). In line with this trend, the T393C polymorphism significantly interacted with drinking status in the association with systolic blood pressure (p = 0.028). Moreover, supporting the presence of an interaction, T allele carriers consistently had a higher probability of hypertension, higher systolic blood pressure, and higher diastolic blood pressure than CC homozygotes in non-drinkers and light drinkers. In contrast, CC homozygotes consistently had a higher probability of hypertension, higher systolic blood pressure, and higher diastolic blood pressure than T allele carriers in moderate to heavy drinkers. The present study also showed a significant interaction between the T393C polymorphism and drinking status in the association with pulse pressure (p = 0.026), reflected by a significant association between the T393C polymorphism and pulse pressure in moderate to heavy drinkers (p = 0.026). These findings may be helpful in conducting further molecular and biological studies on the relationship among the effects of alcohol, the beta-AR-Gs protein system, and hypertension.

    Hypertension research : official journal of the Japanese Society of Hypertension 2003;26;6;439-44

  • Identification of tetratricopeptide repeat 1 as an adaptor protein that interacts with heterotrimeric G proteins and the small GTPase Ras.

    Marty C, Browning DD and Ye RD

    Department of Pharmacology, College of Medicine, University of Illinois, Chicago, Illinois 60612, USA.

    The biological functions of heterotrimeric G proteins and small GTPases are modulated by both extracellular stimuli and intracellular regulatory proteins. Using Saccharomyces cerevisiae two-hybrid screening, we identified tetratricopeptide repeat 1 (TPR1), a 292-amino-acid protein with three TPR motifs, as a Galpha16-binding protein. The interaction was confirmed both in vitro and in transfected mammalian cells, where TPR1 also binds to several other Galpha proteins. TPR1 was found to interact with Ha-Ras preferentially in its active form. Overexpression of TPR1 promotes accumulation of active Ras. TPR1 was found to compete with the Ras-binding domain (RBD) of Raf-1 for binding to the active Ras, suggesting that it may also compete with Ras GTPase-activating protein, thus contributing to the accumulation of GTP-bound Ras. Expression of Galpha16 strongly enhances the interaction between TPR1 and Ras. Removal of the TPR1 N-terminal 112 residues abolishes potentiation by Galpha16 while maintaining the interaction with Galpha16 and the ability to discriminate active Ras from wild-type Ras. We have also observed that LGN, a Galphai-interacting protein with seven TPR motifs, binds Ha-Ras. Thus, TPR1 is a novel adaptor protein for Ras and selected Galpha proteins that may be involved in protein-protein interaction relating to G-protein signaling.

    Funded by: NIAID NIH HHS: AI33503, AI40176, R01 AI033503, R01 AI040176, R56 AI033503, R56 AI040176

    Molecular and cellular biology 2003;23;11;3847-58

  • Functional polymorphisms in the paternally expressed XLalphas and its cofactor ALEX decrease their mutual interaction and enhance receptor-mediated cAMP formation.

    Freson K, Jaeken J, Van Helvoirt M, de Zegher F, Wittevrongel C, Thys C, Hoylaerts MF, Vermylen J and Van Geet C

    Center of Molecular and Vascular Biology and Department of Pediatrics, University Hospital Gasthuisberg, University of Leuven, Leuven, Belgium.

    The paternally expressed extra-large stimulatory G protein gene (XLalphas) is a splice variant of the stimulatory G-protein gene (Gsalpha) consisting of XL-exon1 and exons 2-13 of Gsalpha. A second open reading frame (ORF) in XL-exon1, that completely overlaps the XL-domain ORF, encodes ALEX, which is translated from the XLalphas mRNA and binds the XL-domain of XLalphas. We previously demonstrated that a paternally inherited functional polymorphism in XL-exon1, consisting of a 36 bp insertion and two nucleotide substitutions, is associated with Gs hyperfunction in platelets, leading to an increased trauma-related bleeding tendency and is accompanied by neurological problems and brachydactyly in two families. Here, we describe eight additional patients with brachydactyly, who inherited the same XLalphas polymorphism paternally and who show Gs hyperfunct 1178 ion in their platelets and fibroblasts. All carriers also have an elongated ALEX protein, as a consequence of the paternally inherited insertion. The in vitro interaction between the two elongated XLalphas and ALEX proteins is markedly reduced. Moreover, XLalphas or ALEX can be co-immunoprecipitated with an antibody against either ALEX or XLalphas in platelets from a control but hardly from patients with the XLalphas/ALEX insertion. In contrast to the strong interaction between the two wild-type proteins, we suggest that this defective association results in unimpeded receptor-stimulated activation of XLalphas. The paternally inherited double XLalphas/ALEX functional polymorphism is also associated with elevated platelet membrane Gsalpha protein levels. Both phenomena contribute to increased Gs signaling in patients with platelet hypersensitivity towards Gs-agonists and may be accompanied by neurological problems or growth deficiency.

    Human molecular genetics 2003;12;10;1121-30

  • Exploring proteomes and analyzing protein processing by mass spectrometric identification of sorted N-terminal peptides.

    Gevaert K, Goethals M, Martens L, Van Damme J, Staes A, Thomas GR and Vandekerckhove J

    Department of Medical Protein Research, Flanders Interuniversity Institute for Biotechnology, Ghent University, A. Baertsoenkaai 3, B-9000 Ghent, Belgium. kris.gevaert@rug.ac.be

    Current non-gel techniques for analyzing proteomes rely heavily on mass spectrometric analysis of enzymatically digested protein mixtures. Prior to analysis, a highly complex peptide mixture is either separated on a multidimensional chromatographic system or it is first reduced in complexity by isolating sets of representative peptides. Recently, we developed a peptide isolation procedure based on diagonal electrophoresis and diagonal chromatography. We call it combined fractional diagonal chromatography (COFRADIC). In previous experiments, we used COFRADIC to identify more than 800 Escherichia coli proteins by tandem mass spectrometric (MS/MS) analysis of isolated methionine-containing peptides. Here, we describe a diagonal method to isolate N-terminal peptides. This reduces the complexity of the peptide sample, because each protein has one N terminus and is thus represented by only one peptide. In this new procedure, free amino groups in proteins are first blocked by acetylation and then digested with trypsin. After reverse-phase (RP) chromatographic fractionation of the generated peptide mixture, internal peptides are blocked using 2,4,6-trinitrobenzenesulfonic acid (TNBS); they display a strong hydrophobic shift and therefore segregate from the unaltered N-terminal peptides during a second identical separation step. N-terminal peptides can thereby be specifically collected for further liquid chromatography (LC)-MS/MS analysis. Omitting the acetylation step results in the isolation of non-lysine-containing N-terminal peptides from in vivo blocked proteins.

    Nature biotechnology 2003;21;5;566-9

  • Human brain synembryn interacts with Gsalpha and Gqalpha and is translocated to the plasma membrane in response to isoproterenol and carbachol.

    Klattenhoff C, Montecino M, Soto X, Guzmán L, Romo X, García MA, Mellstrom B, Naranjo JR, Hinrichs MV and Olate J

    Departamento de Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.

    Heterotrimeric G-proteins transduce signals from heptahelical transmembrane receptors to different effector systems, regulating diverse complex intracellular pathways and functions. In brain, facilitation of depolarization-induced neurotransmitter release for synaptic transmission is mediated by Gsalpha and Gqalpha. To identify effectors for Galpha-proteins, we performed a yeast two-hybrid screening of a human brain cDNA library, using the human Galphas protein as a bait. We identified a protein member of the synembryn family as one of the interacting proteins. Extending the study to other Galpha subunits, we found that Gqalpha also interacts with synembryn, and these interactions were confirmed by in vitro pull down studies and by in vivo confocal laser microscopy analysis. Furthermore, synembryn was shown to translocate to the plasma membrane in response to carbachol and isoproterenol. This study supports recent findings in C. elegans where, through genetic studies, synembryn was shown to act together with Gqalpha regulating neuronal transmitter release. Based on these observations, we propose that synembryn is playing a similar role in human neuronal cells.

    Journal of cellular physiology 2003;195;2;151-7

  • Is McCune-Albright syndrome overlooked in subjects with fibrous dysplasia of bone?

    Hannon TS, Noonan K, Steinmetz R, Eugster EA, Levine MA and Pescovitz OH

    Department of Pediatrics, Section of Pediatric Endocrinology/Diabetology, James Whitcomb Riley Hospital for Children, Indianapolis, Indiana 46202, USA. tshannon@iupui.edu

    Objective: McCune-Albright syndrome (MAS) is characterized by a clinical triad of endocrinopathies, café au lait pigmentation, and polyostotic fibrous dysplasia of bone. We hypothesized that children diagnosed with fibrous dysplasia are not routinely being evaluated for coexisting endocrine dysfunction or MAS. Our objective was to prospectively screen subjects with fibrous dysplasia for endocrine disease and G(s)alpha gene (GNAS1 )-activating mutations.

    Nine subjects who presented with fibrous dysplasia and were followed in orthopedic clinics were evaluated for other manifestations of MAS. Genomic DNA was isolated from blood, and mutation analysis of GNAS1 was performed.

    Results: On physical examination, 5 of 9 subjects were found to have café au lait pigmentation. Three of 9 subjects had TSH levels below the normal range. One of these subjects was found to have hyperthyroidism and was treated by total thyroidectomy. GNAS1 mutations were identified in 5 of 9 subjects with either monostotic or polyostotic fibrous dysplasia of bone.

    Conclusions: We conclude that a substantial proportion of children being followed for fibrous dysplasia of bone have unrecognized clinical and laboratory features of MAS. These children are at risk for endocrinopathy and should be screened accordingly.

    Funded by: NCRR NIH HHS: M01 RR00052; NIDDK NIH HHS: 1R01 DK34281

    The Journal of pediatrics 2003;142;5;532-8

  • Molecular analysis of the GNAS1 gene for the correct diagnosis of Albright hereditary osteodystrophy and pseudohypoparathyroidism.

    De Sanctis L, Romagnolo D, Olivero M, Buzi F, Maghnie M, Scirè G, Crino A, Baroncelli GI, Salerno M, Di Maio S, Cappa M, Grosso S, Rigon F, Lala R, De Sanctis C and Dianzani I

    Department of Pediatric Sciences, 94, Piazza Polonia, 10126 Torino, Italy; ldesanct@pediatria.unito.it

    Pseudohypoparathyroidism (PHP) is a heterogeneous disease characterized by PTH resistance and classified as types Ia, Ib, Ic, and II, according to its different pathogenesis and phenotype. PHP-Ia patients show Gsalpha protein deficiency, PTH resistance, and typical Albright hereditary osteodystrophy (AHO). Heterozygous mutations in the GNAS1 gene encoding the Gsalpha protein have been identified both in PHP-Ia and in pseudopseudohypoparathyroidism (PPHP), a disorder with isolated AHO. A single GNAS1 mutation may be responsible for both PHP-Ia and PPHP in the same family when inherited from the maternal and the paternal allele, respectively, suggesting that GNAS1 is an imprinted gene. To evaluate whether molecular diagnosis is a useful tool to characterize AHO and PHP when testing for Gsalpha activity and PTH resistance is not available, we have performed GNAS1 mutational analysis in 43 patients with PTH resistance and/or AHO. Sequencing of the whole coding region of the GNAS1 gene identified 11 mutations in 18 PHP patients, eight of which have not been reported previously. Inheritance was ascertained in 13 cases, all of whom had PHP-Ia: the mutated alleles were inherited from the mothers, who had AHO (PPHP), consistent with the proposed imprinting mechanism. GNAS1 molecular analysis confirmed the diagnosis of PHP-Ia and PPHP in the mutated patients. Our results stress the usefulness of this approach to obtain a complete diagnosis, expand the GNAS1 mutation spectrum, and illustrate the wide mutation heterogeneity of PHP and PHP-Ia.

    Pediatric research 2003;53;5;749-55

  • Progressive osseous heteroplasia in the face of a child.

    Faust RA, Shore EM, Stevens CE, Xu M, Shah S, Phillips CD and Kaplan FS

    Department of Otolaryngology and Pediatrics, Children's Hospital of Michigan, Detroit, 48201, USA. rfaust@dmc.org

    We describe a rare case of progressive osseous heteroplasia of the face in a child. Biopsy showed osteoma cutis superficially with ectopic bone formation in the deeper tissues including skeletal muscle. Analysis of DNA from peripheral blood leukocytes showed mutations in the gene encoding the alpha subunit of the stimulatory G protein of adenylyl cyclase (GNAS1), confirming the diagnosis of progressive osseous heteroplasia.

    American journal of medical genetics. Part A 2003;118A;1;71-5

  • A new heterozygous mutation (L338N) in the human Gsalpha (GNAS1) gene as a cause for congenital hypothyroidism in Albright's hereditary osteodystrophy.

    Pohlenz J, Ahrens W and Hiort O

    Children's Hospital, Johannes Gutenberg-University, Langenbeckstrasse 1, D-55101 Mainz, Germany. pohlenz@mail.uni-mainz.de

    Objective: To identify the molecular defect by which psychomotor retardation is caused in two brothers with congenital hypothyroidism who received adequate treatment with l-thyroxine.

    A six-year-old boy presented with psychomotor retardation and congenital primary hypothyroidism (CH). The patient had a normal blood thyrotrophin (TSH) level on neonatal screening, but low total serum thyroxine and triiodothyronine concentrations prompting thyroid hormone substitution shortly after birth. Nevertheless, psychomotor development was retarded and the patient underwent further investigation. Typical features of Albright's hereditary osteodystrophy (AHO) such as round face, obesity, and shortened 1st, 4th and 5th metacarpals were found.

    Further investigation confirmed AHO with pseudohypoparathyroidism (PHP) type Ia. The boy had a mild resistance to parathyroid hormone and a reduced adenylyl cyclase stimulating protein (Gsalpha) activity in erythrocytes. DNA analysis detected a new heterozygous mutation (L338N) in the Gsalpha protein (GNAS1) gene. This mutation was also present in the patient's brother who had similar features and was also treated with thyroid hormone because of CH, and in the phenotypically normal-looking mother who had a normal calcium metabolism but a reduced Gsalpha protein activity in erythrocytes suggestive of pseudopseudohypoparathyroidism.

    Conclusion: In patients with CH, in whom the neurological outcome is poor even under adequate thyroid hormone substitution, PHP Ia may be suspected, especially when symptoms of AHO are present.

    European journal of endocrinology 2003;148;4;463-8

  • Analysis of GNAS1 and overlapping transcripts identifies the parental origin of mutations in patients with sporadic Albright hereditary osteodystrophy and reveals a model system in which to observe the effects of splicing mutations on translated and untranslated messenger RNA.

    Rickard SJ and Wilson LC

    Clinical and Molecular Genetics Unit, Institute of Child Health, and Great Ormond Street Hospital NHS Trust, London, United Kingdom.

    Albright hereditary osteodystrophy (AHO) is caused by heterozygous deactivating GNAS1 mutations. There is a parent-of-origin effect. Maternally derived mutations are usually associated with resistance to parathyroid hormone termed "pseudohypoparathyroidism type Ia." Paternally derived mutations are associated with AHO but usually normal hormone responsiveness, known as "pseudo-pseudohypoparathyroidism." These observations can be explained by tissue-specific GNAS1 imprinting. Regulation of the genomic region that encompasses GNAS1 is complex. At least three upstream exons that splice to exon 2 of GNAS1 and that are imprinted have been reported. NESP55 is exclusively maternally expressed, whereas exon 1A and XL alphas are exclusively paternally expressed. We set out to identify the parental origin of GNAS1 mutations in patients with AHO by searching for their mutation in the overlapping transcripts. This information would be of value in patients with sporadic disease, for predicting their endocrine phenotype and planning follow-up. In doing so, we identified mutations that resulted in nonsense-mediated decay of the mutant Gs alpha transcript but that were detectable in NESP55 messenger RNA (mRNA), probably because they lie within its 3' untranslated region. Analysis of the NESP55 transcripts revealed the creation of a novel splice site in one patient and an unusual intronic mutation that caused retention of the intron in a further patient, neither of which could be detected by analysis of the Gs alpha complementary DNA. This cluster of overlapping transcripts represents a useful model system in which to analyze the effects that mutant sequence has on mRNA-in particular, splicing-and the mechanisms of nonsense-mediated mRNA decay.

    American journal of human genetics 2003;72;4;961-74

  • Glucagon and regulation of glucose metabolism.

    Jiang G and Zhang BB

    Department of Metabolic Disorders and Molecular Endocrinology, Merck Research Laboratory, Rahway, New Jersey 07065, USA.

    As a counterregulatory hormone for insulin, glucagon plays a critical role in maintaining glucose homeostasis in vivo in both animals and humans. To increase blood glucose, glucagon promotes hepatic glucose output by increasing glycogenolysis and gluconeogenesis and by decreasing glycogenesis and glycolysis in a concerted fashion via multiple mechanisms. Compared with healthy subjects, diabetic patients and animals have abnormal secretion of not only insulin but also glucagon. Hyperglucagonemia and altered insulin-to-glucagon ratios play important roles in initiating and maintaining pathological hyperglycemic states. Not surprisingly, glucagon and glucagon receptor have been pursued extensively in recent years as potential targets for the therapeutic treatment of diabetes.

    American journal of physiology. Endocrinology and metabolism 2003;284;4;E671-8

  • Prostaglandin D2 inhibits the production of interleukin-12 in murine dendritic cells through multiple signaling pathways.

    Faveeuw C, Gosset P, Bureau F, Angeli V, Hirai H, Maruyama T, Narumiya S, Capron M and Trottein F

    Inserm U547, Institut Pasteur de Lille, Lille, France.

    Prostaglandin (PG) D(2), and its metabolites, are known to be important mediators during acute and chronic inflammation. However, their functions during the early phases of the immune response are poorly documented. In the present study, we show that PGD(2 )inhibits, in a dose-dependent manner, the CD40- and LPS-induced secretion of the Th1-driving factor IL-12 by murine splenic dendritic cells (DC), the most potent antigen-presenting cells. The inhibition of IL-12 production is mediated only in part by the cell surface G alpha s protein-coupled D prostanoid receptor (termed DP1) but not by the G alpha i protein-coupled DP receptor, DP2. We show that recruitment of DP1 in DC results in the activation of a cyclic AMP/protein kinase A pathway that is partially responsible for the inhibition of IL-12 production. We also suggest that the DP1-independent effects exerted by PGD(2) on IL-12 production may be due to the action of ist PGJ(2), but not PGF(2)alpha, metabolites. Electrophoretic mobility shift assays demonstrated that PGD(2) affects NF-kappa B activation through (the) DP1-independent pathway(s). Together these data suggest that PGD(2), by interacting with DP1 and by binding to other target cellular proteins, may regulate immune responses by affecting IL-12 production in DC.

    European journal of immunology 2003;33;4;889-98

  • The pseudohypoparathyroidism type lb locus is linked to a region including GNAS1 at 20q13.3.

    Jan De Beur SM, O'Connell JR, Peila R, Cho J, Deng Z, Kam S and Levine MA

    Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21224, USA. sjandebe@jhmi.edu

    Pseudohypoparathyroidism (PHP) is characterized by biochemical hypoparathyroidism with elevated parathyroid hormone levels owing to reduced target tissue responsiveness to parathyroid hormone. Patients with PHP la have somatic defects termed Albright's hereditary osteodystrophy (AHO) and exhibit resistance to additional hormones because of heterozygous mutations in the GNAS1 gene that lead to a generalized deficiency of the a subunit of Gs, the heterotrimeric G protein that couples receptors to adenylyl cyclase. By contrast, patients with PHP 1b lack AHO and have selective parathyroid hormone (PTH) resistance, presumably because of an imprinting defect that impairs expression of G(s)alpha in the proximal renal tubule. Although an epigenetic defect in GNAS1 has been identified in subjects with PHP1b, the genetic defect is unknown. To define the genetic defect in PHP 1b, we performed a genome-wide linkage analysis in five multi-generational PHP lb families. Of the 408 polymorphic microsatellite markers examined, markers located on chromosome 20q13.3, the region containing GNAS1, demonstrated linkage to PHP lb. Fine-mapping and multipoint linkage analysis of this region demonstrated linkage to a 5.7-cM region between 907rep2 and the telomere. Haplotype analysis established that affected individuals shared a 5-cM region including part of the GNAS1 gene to the telomere. Our data confirm that PHP1b is linked to a region that includes GNAS1, and further refine the locus, although the primary genetic mutation(s) that causes defective imprinting of GNAS1 remains undefined.

    Funded by: NCRR NIH HHS: M01RR00052; NIA NIH HHS: AG16992; NIDDK NIH HHS: R01DK46720; Unspecified: T32DK07751

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2003;18;3;424-33

  • Palmitoylation of the human prostacyclin receptor. Functional implications of palmitoylation and isoprenylation.

    Miggin SM, Lawler OA and Kinsella BT

    Department of Biochemistry, Conway Institute of Biomolecular and Biomedical Research, Merville House, University College Dublin, Belfield, Dublin 4, Ireland.

    We have previously established that isoprenylation of the prostacyclin receptor (IP) is required fo 1c48 r its efficient G protein coupling and effector signaling (Hayes, J. S., Lawler, O. A., Walsh, M. T., and Kinsella, B. T. (1999) J. Biol. Chem. 274, 23707-23718). In the present study, we sought to investigate whether the IP may actually be subject to palmitoylation in addition to isoprenylation and to establish the functional significance thereof. The human (h) IP was efficiently palmitoylated at Cys(308) and Cys(311), proximal to transmembrane domain 7 within its carboxyl-terminal (C)-tail domain, whereas Cys(309) was not palmitoylated. The isoprenylation-defective hIP(SSLC) underwent palmitoylation but did not efficiently couple to G(s) or G(q), confirming that isoprenylation is required for G protein coupling. Deletion of C-tail sequences distal to Val(307) generated hIP(Delta307) that was neither palmitoylated nor isoprenylated and did not efficiently couple to G(s) or to G(q), whereas hIP(Delta312) was palmitoylated and ably coupled to both effector systems. Conversion of Cys(308), Cys(309), Cys(311), Cys(308,309), or Cys(309,311) to corresponding Ser residues, while leaving the isoprenylation CAAX motif intact, did not affect hIP coupling to G(s) signaling, whereas mutation of Cys(308,311) and Cys(308,309,311) abolished signaling, indicating that palmitoylation of either Cys(308) or Cys(311) is sufficient to maintain functional G(s) coupling. Although mutation of Cys(309) and Cys(311) did not affect hIP-mediated G(q) coupling, mutation of Cys(308) abolished signaling, indicating a specific requirement for palmitoylation of Cys(308) for G(q) coupling. Consistent with this, neither hIP(C308S,C309S), hIP(C308S,C311S), nor hIP(C308S,C309S,C311S) coupled to G(q). Taken together, these data confirm that the hIP is isoprenylated and palmitoylated, and collectively these modifications modulate its G protein coupling and effector signaling. We propose that through lipid modification followed by membrane insertion, the C-tail domain of the IP may contain a double loop structure anchored by the dynamically regulated palmitoyl groups proximal to transmembrane domain 7 and by a distal farnesyl isoprenoid permanently attached to its carboxyl terminus.

    The Journal of biological chemistry 2003;278;9;6947-58

  • Pseudohypoparathyroidism type Ib with disturbed imprinting in the GNAS1 cluster and Gsalpha deficiency in platelets.

    Freson K, Thys C, Wittevrongel C, Proesmans W, Hoylaerts MF, Vermylen J and Van Geet C

    Center for Molecular and Vascular Biology, Leuven, Belgium.

    Pseudohypoparathyroidism Ib (PHPIb), characterized by parathyroid hormone-resistant hypocalcemia and hyperphosphatemia, is caused by a deregulation in the imprinting status of the GNAS1 cluster, comprising exons XL, NESP55 and 1A and the coding exons of Gsalpha. Differences in methylation of exon 1A and sporadically also of exons XL and NESP55 were found and thought to result in long-range effects on Gsalpha expression, limited to the proximal renal tubules. The exact imprinting defect is not precisely localized, and the expected differences in Gsalpha protein level and function are mainly hypothetical. We describe a PHPIb patient with lack of methylation of the exon XL and 1A promoters, and biallelic methylation of the NESP55 promoter. Platelets of this patient show a functional Gs defect, decreased cAMP formation upon Gs-receptor stimulation, normal Gsalpha sequence but reduced Gsalpha protein levels. Transcriptional deregulation between the now biallelically active promoters of both exon 1A and exon 1 of Gsalpha could explain the decreased Gsalpha expression in platelets and presumably in the proximal renal tubules. We found decreased NESP55 and increased XLalphas protein levels in platelets, in agreement with the methylation status of their corresponding first exons. In a megakaryocytic cell line MEG-01, exon 1A is methylated on both alleles, in contrast to the normally maternally methylated exon 1A in leukocytes. Experimental demethylation of exon 1A in MEG-01 cells led to reduced Gsalpha expression, in agreement with the observations in the patient. Platelet studies may therefore allow easy evaluation of disturbances of the GNAS1 cluster in PHPIb patients.

    Human molecular genetics 2002;11;22;2741-50

  • The gsalpha gene: predom 1426 inant maternal origin of transcription in human thyroid gland and gonads.

    Mantovani G, Ballare E, Giammona E, Beck-Peccoz P and Spada A

    Institute of Endocrine Sciences-University of Milan, Ospedale Maggiore IRCCS, Milan.

    Mutations in the guanine nucleotide binding alpha-subunit 1 gene (GNAS1) cause Albright's hereditary osteodistrophy, and the parent of transmission determines variable phenotypic expression of the disease. This has suggested that GNAS1 may be under tissue-specific imprinting control, although studies so far available have failed to clearly define the pattern of GNAS1 expression in humans. To establish if GNAS1 is imprinted in human endocrine tissues, we selected 14 thyroid, 10 granulosa cell, 13 pituitary (3 normal glands, 7 GH-secreting adenomas, and 3 nonfunctioning adenomas), 3 adrenal, and 11 lymphocyte samples shown to be heterozygous for a known polymorphism in exon 5. RNA from these tissues was analyzed by RT-PCR, and expression from both parental alleles was evaluated by enzymatic digestion and subsequent quantification of the resulting fragments. The parental origin of Gs alpha was assessed by evaluating neuroendocrine secretory protein 55 and extra large alphas-like protein transcripts, which have been shown to be monoallelically and parent-specifically expressed from the maternal and paternal allele, respectively. By this approach, the great majority of thyroid (n = 12), ovarian (n = 7), and pituitary (n = 11) samples showed an almost exclusive or significantly predominant expression of the maternal allele over the paternal one, whereas in lymphocyte and adrenal samples both alleles were equally expressed. Our results provide evidence for a predominant maternal origin of GNAS1 transcripts in different human adult endocrine tissues, particularly thyroid, ovary, and pituitary, and strongly suggest that this mechanism may play a crucial role in the determination of the phenotypic expression of Albright's hereditary osteodistrophy.

    The Journal of clinical endocrinology and metabolism 2002;87;10;4736-40

  • Association of GNAS1 gene variant with hypertension depending on smoking status.

    Abe M, Nakura J, Yamamoto M, Jin JJ, Wu Z, Tabara Y, Yamamoto Y, Igase M, Kohara K and Miki T

    Department of Geriatric Medicine, School of Medicine, Ehime University, Shigenobu-cho, Onsen-gun, Ehime 791-0295, Japan.

    The beta-adrenoceptor (beta-AR) G(s) protein system has been shown to have important roles in the cardiovascular system. The gene encoding the alpha-subunit of G(s) proteins (GNAS1) is a candidate genetic determinant for hypertension. We studied the GNAS1 T393C polymorphism in >2000 Japanese individuals. chi(2) test showed a marginally significant difference in the frequencies of the alleles (P=0.036) and genotypes (P=0.094) between hypertensives and normotensives. Because hypertension is considered to be a complex disorder resulting from interactions between genetic and environmental factors, we further analyzed the T393C polymorphism, with conside 19b2 ration of interactions between the polymorphism and confounding factors in regression models. These analyses showed a significant interaction between the polymorphism and cigarette smoking in the pathogenesis of hypertension (P=0.0005). The interaction was reflected in a significant association of the polymorphism with hypertension in nonheavy smokers (P=0.0028; odds ratio, 1.52; 95% confidence interval, 1.16 to 2.00). A significant interaction between the polymorphism and aging in the pathogenesis of hypertension was also shown in nonheavy smokers. These findings may be helpful in conducting further molecular and biological studies on the relationship among cigarette smoking, the beta-AR-G(s) protein system, and hypertension.

    Hypertension (Dallas, Tex. : 1979) 2002;40;3;261-5

  • Paternal imprinting of Galpha(s) in the human thyroid as the basis of TSH resistance in pseudohypoparathyroidism type 1a.

    Germain-Lee EL, Ding CL, Deng Z, Crane JL, Saji M, Ringel MD and Levine MA

    Division of Pediatric Endocrinology, Department of Pediatrics, The Johns Hopkins University School of Medicine, Park Building, Suite 211, 600 N. Wolfe Street, Baltimore, 21287-2520, MD, USA. egermain@jhmi.edu

    Albright hereditary osteodystrophy (AHO) is characterized by multiple somatic defects secondary to mutations in the GNAS1 gene. AHO patients with mutations on maternally inherited alleles are resistant to multiple hormones (e.g., PTH, TSH), a variant termed pseudohypoparathyroidism (PHP) type 1a, due to presumed tissue-specific paternal imprinting of the alpha chain of G(s) as demonstrated in murine renal proximal tubule and fat cells. Studies in human tissues thus far revealed imprinting only in pituitary. Because mild hypothyroidism due to TSH resistance occurs in most PHP type 1a patients, we investigated whether Galpha(s) is imprinted in thyroid. Examination of eight normal thyroids demonstrated significantly greater expression from the maternal GNAS1 allele, with paternal Galpha(s) transcripts accounting for only 25.9-40.4%. Expression of NESP55, XLalpha(s), and 1A was uniallelic. We conclude that Galpha(s) is incompletely imprinted in the thyroid, which provides an explanation for mild TSH resistance in PHP type 1a.

    Funded by: NCRR NIH HHS: M01 RR00052; NIDDK NIH HHS: DK56178, R01 DK34281, R01 DK56178

    Biochemical and biophysical research communications 2002;296;1;67-72

  • Association analysis of a polymorphism in the G-protein stimulatory alpha subunit in patients with major depression.

    Zill P, Baghai TC, Zwanzger P, Schüle C, Minov C, Behrens S, Rupprecht R, Möller HJ, Engel R and Bondy B

    Psychiatric Hospital of the Ludwig-Maximilians-University, Munich, Germany. Peter.Zill@psy.med.uni-muenchen.de

    Growing evidence suggests that G-proteins may be involved in pathogenesis and treatment of affective disorders. Several studies have reported altered levels and/or activities of stimulatory G-proteins in depression. The aim of this study was to investigate whether a polymorphism in the stimulatory alpha subunit of G-proteins (T/C point mutation in exon 5; ATT --> ATC at codon 131) is associated with major depression or response to antidepressant treatment. Therefore, we performed a case-control association study with 212 depressive patients and 137 healthy, unrelated controls. There was no evidence for an association between the investigated polymorphism in the G(alpha)(s) gene and major depression, as well as to treatment response. The results of our study are in concordance with recently published findings which do not support the hypothesis that the gene for the stimulatory alpha subunit of G-proteins is a major susceptibility factor in the pathophysiology of major depression.

    American journal of medical genetics 2002;114;5;530-2

  • Similarities and differences in the coupling of human beta1- and beta2-adrenoceptors to Gs(alpha) splice variants.

    Wenzel-Seifert K, Liu HY and Seifert R

    Department of Pharmacology and Toxicology, The University of Kansas, Malott Hall, Room 5064, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.

    The human beta1-adrenoceptor (beta1AR) and beta2-adrenoceptor (beta2AR) couple to Gs-proteins to activate adenylyl cyclase (AC). There are differences in desensitization between the beta2AR and the originally cloned Gly389-beta1AR, but with respect to ternary complex formation, constitutive activity, and AC activation the picture is unclear. To learn more about the similarities and differences between the beta1AR and beta2AR, we analyzed coupling of the Gly389-beta1AR to the G(s(alpha)) splice variants Gs(alpha)L and Gs(alpha)S using beta1AR-Gs(alpha) fusion proteins expressed in Sf9 cells and compared the data with previously published data on beta2AR-Gs(alpha) fusion proteins (Seifert et al., J Biol Chem 1998;273:5109-16). Fusion ensures defined receptor/G-protein stoichiometry and efficient coupling. The agonist (-)-isoproterenol stabilized the ternary complex at beta1AR-Gs(alpha)S, beta1AR-Gs(alpha)L, beta2AR-Gs(alpha)S, and beta2AR-Gs(alpha)L with similar efficiency. beta1AR-Gs(alpha)L but not beta1AR-Gs(alpha)S showed the hallmarks of constitutive activity as assessed by increased potencies and efficacies of partial agonists and AC activation by the agonist-free receptor. Similar differences were observed previously for beta2AR-Gs(alpha)S and beta2AR-Gs(alpha)L. beta1AR-Gs(alpha)S and beta2AR-Gs(alpha)S were similarly efficient at activating AC, but beta1AR-Gs(alpha)L was approximately 4-fold more efficient at activating AC than beta2AR-Gs(alpha)L. Our data show that (i) the beta1AR and beta2AR are similarly efficient at stabilizing the ternary complex with Gs(alpha) splice variants, (ii) Gs(alpha)L confers constitutive activity to the beta1AR and beta2AR, and (iii) the beta1AR coupled to Gs(alpha)L is more efficient at activating AC than the beta2AR coupled to Gs(alpha)L. These data help us understand some of the discrepancies regarding similarities and differences between the beta1AR and beta2AR.

    Biochemical pharmacology 2002;64;1;9-20

  • Chromosomal assignments of expressed sequence tags for ACTG1, AHSG, COL1A1, GNAS1, and RPLP1 expressed abundantly in the bovine foetus.

    Muramatsu Y, Lejukole HY, Taniguchi Y, Konfortov BA, Yamada T, Yasue H and Sasaki Y

    Department of Food Science, Shizuoka Eiwa College, Ikeda, Shizuoka 422-8005, Japan.

    Animal genetics 2002;33;3;230-1

  • Gs(alpha) mutations and imprinting defects in human disease.

    Weinstein LS, Chen M and Liu J

    Metabolic Diseases Branch, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. leew@amb.niddk.nih.gov

    Gs is the ubiquitously expressed heterotrimeric G protein that couples receptors to the effector enzyme adenylyl cyclase and is required for receptor-stimulated intracellular cAMP generation. Activated receptors promote the exchange of GTP for GDP on the Gs alpha-subunit (Gs(alpha)), resulting in Gs activation; an intrinsic GTPase activity of Gs(alpha) deactivates Gs by hydrolyzing bound GTP to GDP. Mutations of Gs(alpha) residues involved in the GTPase reaction that lead to constitutive activation are present in endocrine tumors, fibrous dysplasia of bone, and McCune-Albright syndrome. Heterozygous loss-of-function mutations lead to Albright hereditary osteodystrophy (AHO), a disease characterized by short stature, obesity, and skeletal defects, and are sometimes associated with progressive osseous heteroplasia. Maternal transmission of Gs(alpha) mutations leads to AHO plus resistance to several hormones (e.g., parathyroid hormone) that activate Gs in their target tissues (pseudohypoparathyroidism type IA), while paternal transmission leads only to the AHO phenotype (pseudopseudohypoparathyroidism). Studies in both mice and humans demonstrate that Gs(alpha) is imprinted in a tissue-specific manner, being expressed primarily from the maternal allele in some tissues and biallelically expressed in most other tissues. This likely explains why multihormone resistance occurs only when Gs(alpha) mutations are inherited maternally. The Gs(alpha) gene GNAS1 has at least four alternative promoters and first exons, leading to the production of alternative gene products including Gs(alpha), XL alphas (a novel Gs(alpha) isoform expressed only from the paternal allele), and NESP55 (a chromogranin-like protein expressed only from the maternal allele). The fourth alternative promoter and first exon (exon 1A) located just upstream of the Gs(alpha) promoter is normally methylated on the maternal allele and is transcriptionally active on the paternal allele. In patients with parathyroid hormone resistance but without AHO (pseudohypoparathyroidism type IB), the exon 1A promoter region is unmethylated and transcriptionally active on both alleles. This GNAS1 imprinting defect is predicted to decrease Gs(alpha) expression in tissues where Gs(alpha) is normally imprinted and therefore to lead to renal parathyroid hormone resistance.

    Annals of the New York Academy of Sciences 2002;968;173-97

  • GNAS1 mutations and progressive osseous heteroplasia.

    Ahmed SF, Barr DG and Bonthron DT

    The New England journal of medicine 2002;346;21;1669-71

  • Polymorphisms of genes encoding components of the sympathetic nervous system but not the renin-angiotensin system as risk factors for orthostatic hypotension.

    Tabara Y, Kohara K and Miki T

    Department of Geriatric Medicine, Ehime University School of Medicine, Shigenobu-cho, Onsen-gun, Ehime, Japan.

    Objective: The genetic background of orthostatic hypotension, an important risk factor for future cardiovascular morbidity and mortality, was investigated.

    The study subjects comprised 415 community-dwelling individuals, who were free from any cardiovascular complications, aged 50 years or older (mean age 70.5 +/- 9 years). Basal systolic blood pressure (SBP) was measured twice in supine posture after resting for more than 10 min. The orthostatic change in SBP was determined at 1 min and 3 min after standing up. The maximum change in SBP after standing was determined. Orthostatic hypotension was defined as a decline in SBP greater than 20 mmHg. The polymorphisms of genes encoding components of the renin-angiotensin system and sympathetic nervous system, which play pivotal roles in postural change in blood pressure regulation, were determined.

    Results: There were no significant associations between the maximum change in SBP, the prevalence of orthostatic hypotension and gene polymorphisms of angiotensin-converting enzyme I/D, angiotensinogen M235T and angiotensin II type 1 receptor A1166C. On the contrary, polymorphism of the Gs protein alpha-subunit (GNAS1) T131C was significantly associated with the maximum change in SBP after standing [1.9 +/- 16 versus -3.6 +/- 16 mmHg (TT + TC versus CC), P = 0.008]. The prevalence of orthostatic hypotension was significantly different among GNAS1 genotypes (chi squared = 10.12, P = 0.011) and G-protein beta 3 subunit (GNB3) genotypes (chi squared = 6.12, P = 0.020). Multiple logistic regression analysis showed that both GNAS1 CC genotype [odds ratio (OR) = 2.79, 95% confidence interval (CI) 1.35-5.79, P = 0.006] and GNB3 C allele (OR = 1.78, 95% CI 1.06-3.00, P = 0.030) were independent risks for orthostatic hypotension.

    Conclusions: These findings indicate that genes encoding sympathetic nervous components could be involved in the predisposition for orthostatic hypotension.

    Journal of hypertension 2002;20;4;651-6

  • Mutational analysis of the GNAS1 exons encoding the stimulatory G protein in five patients with pseudohypoparathyroidism type 1a.

    Lim SH, Poh LK, Cowell CT, Tey BH and Loke KY

    Department of Paediatrics, National University of Singapore, Singapore.

    We analyzed the GNAS1 gene in five patients with pseudohypoparathyroidism type 1a (PHP1a) by performing polymerase chain reaction, followed by sequencing all 13 exons of the gene, single-stranded conformational polymorphism (SSCP) or heteroduplex analysis (HD). Three novel mutations were discovered: (1) a de novo 3 bp insertion of CTG in codon 47 of exon 1; (2) a missense mutation 1103T in exon 4; and (3) a de novo mutation of Arg280Gly in exon 10. Two other mutations, previously described in the literature, include: (1) a de novo 4 bp deletion (deltaGACT) involving codons 189 and 190 in exon 7, and (2) a deletion of a cytosine nucleotide at codon 115 in exon 5. We conclude that mutational analysis of the GNAS1 gene is a strong supportive tool for the diagnosis of PHP1a, and is a useful adjunct to the synthetic parathyroid hormone infusion test for PTH resistance.

    Journal of pediatric endocrinology & metabolism : JPEM 2002;15;3;259-68

  • Identification of G-proteins coupling to the vasoactive intestinal peptide receptor VPAC(1) using immunoaffinity chromatography: evidence for precoupling.

    Martin Shreeve S

    Department of Pharmacology, University of Vermont, Burlington 05405, USA. Stephen.Shreeve@uvm.edu

    VPAC(1) receptor subtype-specific G-protein interactions were identified using a strategy that exploits an essential initial signaling event, namely the functional and physical association of the receptor with G-protein. An immunoaffinity purification column was constructed using a previously characterized antibody that had been raised against the first extracellular loop of the VPAC(1) receptor. VPAC(1)/G-protein complexes were solubilized from membranes and copurified. Receptor and Galpha-proteins were detected in eluates using (125)I-VIP labeling and immunoblotting, respectively. Human VPAC(1) transfected in HEK293 cells couples to Gs but not Gi3, Gi1/2, or Gq. Rat VPAC(1) in brain membranes is coupled to Gs and Gi3. Rat VPAC(1) in lung membranes couples to Gs, Gi3, and Gq. Pretreatment of membranes with VIP increased the level of all G-pro c1f teins copurifying with VPAC(1). Immunoaffinity chromatography also revealed VPAC(1) receptor precoupling to G-protein in the absence of VIP pretreatment. This was confirmed using a cross-linking procedure to capture VIP receptor/G-protein complexes in the native membrane milieu prior to solubilization. Precoupling suggests that there is a significant basal level of VPAC(1) receptor activity especially in cells, such as some human malignant tumor cells, that express high levels of receptor.

    Biochemical and biophysical research communications 2002;290;4;1300-7

  • An R201H activating mutation of the GNAS1 (Gsalpha) gene in a corticotroph pituitary adenoma.

    Riminucci M, Collins MT, Lala R, Corsi A, Matarazzo P, Gehron Robey P and Bianco P

    Dipartimento di Medicina Sperimentale, Università dell'Aquila, Via Vetoio, Coppito II, 67100 L'Aquila, Roma, Italy.

    In the pituitary gland, activating mutations of the GNAS1 (Gsalpha) gene at Gln227 have been identified in adrenocorticotrophin secreting, growth hormone secreting, and prolactin secreting adenomas. To date, mutations at the codon encoding R201, typically underlying the McCune-Albright syndrome and isolated fibrous dysplasia of bone, have been demonstrated only in growth hormone secreting pituitary adenomas. In this study, a polymerase chain reaction amplified target sequence in exon 8 of the GNAS1 gene was sequenced, identifying the first R201 mutation seen in an isolated basophilic adenoma which generated Cushing's disease in a child. This case adds Cushing's disease to the range of human diseases caused by R201 mutations of the GNAS1 gene.

    Funded by: Telethon: E.1029

    Molecular pathology : MP 2002;55;1;58-60

  • Paternally inherited inactivating mutations of the GNAS1 gene in progressive osseous heteroplasia.

    Shore EM, Ahn J, Jan de Beur S, Li M, Xu M, Gardner RJ, Zasloff MA, Whyte MP, Levine MA and Kaplan FS

    Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia 19104-6018, USA. shore@mail.med.upenn.edu

    Background: Progressive osseous heteroplasia (POH), an autosomal dominant disorder, is characterized by extensive dermal ossification during childhood, followed by disabling and widespread heterotopic ossification of skeletal muscle and deep connective tissue. Occasional reports of mild heterotopic ossification in Albright's hereditary osteodystrophy (AHO) and a recent report of two patients with AHO who had atypically extensive heterotopic ossification suggested a common genetic basis for the two disorders. AHO is caused by heterozygous inactivating mutations in the GNAS1 gene that result in decreased expression or function of the alpha subunit of the stimulatory G protein (Gsalpha) of adenylyl cyclase.

    Methods: We tested the hypothesis that GNAS1 mutations cause POH, using the polymerase chain reaction to amplify GNAS1 exons and exon-intron boundaries in 18 patients with sporadic or familial POH.

    Results: Heterozygous inactivating GNAS1 mutations were identified in 13 of the 18 probands with POH. The defective allele in POH is inherited exclusively from fathers, a result consistent with a model of imprinting for GNAS1. Direct evidence that the same mutation can cause either POH or AHO was observed within a single family, in which the phenotype correlated with the parental origin of the mutant allele.

    Conclusions: Paternally inherited inactivating GNAS1 mutations cause POH. This finding extends the range of phenotypes derived from haplo insufficiency of GNAS1, provides evidence that imprinting is a regulatory mechanism for GNAS1 expression, and suggests that Gsalpha is a critical negative regulator of osteogenic commitment in nonosseous connective tissues.

    Funded by: NIAMS NIH HHS: R01-AR41916, R01-AR46831; NIDDK NIH HHS: R01-DK34281

    The New England journal of medicine 2002;346;2;99-106

  • GTP-binding proteins G(salpha), G(ialpha), and Ran identified in mitochondria of human placenta.

    Kuyznierewicz I and Thomson M

    School of Science Food and Horticulture, Parramatta Campus, University of Western Sydney, Penrith South DC, NSW 1797, Australia.

    GTP-binding proteins (GTPases) have been detected in the mitochondria of human placenta. It has been proposed that porin interacts with GTPases in the mitochondrion to modulate contact site function, however, their identity and location is not known. In this study, we investigated the location of GTPases in mitochondria from term placentae as well as the expression of mitochondrial GTPases in mid-term placentae. Mitochondria obtained from human term and mid-term placentae were purified by sedimentation. Sub-mitochondrial vesicles prepared from ruptured and sonicated mitochondria were separated by ultracentrifugation in sucrose density gradients. The location of membrane vesicles was determined using marker enzymes. Mitochondrial proteins were separated by SDS-PAGE. Western blots were incubated in [alpha-(32)P]-GTP and detected using autoradiography or antibodies against known GTPases and porin followed by enhanced chemiluminescence. [alpha-(32)P]-GTP bound 24 and 28 kDa proteins located in the outer membrane. The G(salpha)antibody detected 42.5, 53 and 67 kDa proteins. The G(ialpha)antibody identified a 40.5 kDa band in contact sites and the outer membrane, as well as 55 and 105 kDa proteins in contact site vesicles. The Ran antibody detected a 28 kDa protein, mainly in the outer membrane. Porin migrated at 30 kDa. G(ialpha)and Ran were detected in mitochondria from both term and mid-term placentae. The location of porin and GTPases leave open the possibility that these proteins interact in contact sites and may also be responding to extra-mitochondrial signals. Ran and G(ialpha)are expressed by mid-term in human placentae and may be necessary for placental functions at this stage of development. It will be important in future experiments to characterise the physiological functions of these GTP-binding proteins in the mitochondria of human placenta.

    Cell biology international 2002;26;1;99-108

  • S111N mutation in the helical domain of human Gs(alpha) reduces its GDP/GTP exchange rate.

    Brito M, Guzmán L, Romo X, Soto X, Hinrichs MV and Olate J

    Departamento de Biología Molecular, Facultad de Ciencias Biológicas, Casilla 160-C, Universidad de Concepción, Concepción, Chile.

    G-protein alpha subunits consist of two domains: a Ras-like domain also called GTPase domain (GTPaseD), structurally homologous to monomeric G-proteins, and a more divergent domain, unique to heterotrimeric G-proteins, called helical domain (HD). G-protein activation, requires the exchange of bound GDP for GTP, and since the guanine nucleotide is buried in a deep cleft between both domains, it has been postulated that activation may involve a conformational change that will allow the opening of this cleft. Therefore, it has been proposed, that interdomain interactions are playing an important role in regulating the nucleotide exchange rate of the alpha subunit. While constructing different Gs(alpha) quimeras, we identified a Gs(alpha) random mutant, which was very inefficient in stimulating adenylyl cyclase activity. The introduced mutation corresponded to the substitution of Ser(111) for Asn (S111N), located in the carboxi terminal end of helix A of the HD, a region neither involved in AC interaction nor in the interdomain interface. In order to characterize this mutant, we expressed it in bacteria, purified it by niquel-agarose chromatography, and studied its nucleotide exchange properties. We demonstrated that the recombinant S111N Gs(alpha) was functional since it was able to undergo the characteristic conformational change upon GTP binding, detected by the acquisition of a trypsin-resistant conformation. When the biochemical properties were determined, the mutant protein exhibited a reduced GDP dissociation kinetics and as a consequence a slower GTPgammaS binding rate that was responsible for a diminished adenylyl cyclase activation when GTPgammaS was used as activator. These data provide new evidence that involves the HD as a regulator of Gs(alpha) function, in this case the alphaA helix, which is not directly involved with the nucleotide binding site nor the interdomain interface.

    Journal of cellular biochemistry 2002;85;3;615-20

  • Searching for Arg201 mutations in the GNAS1 gene in Italian patients with McCune-Albright syndrome.

    de Sanctis L, Romagnolo D, Greggio N, Genitori L, Lala R and de Sanctis C

    Department of Pediatrics, University of Torino, Regina Margherita Children's Hospital, Italy. ldesanct@pediatria.unito.it

    McCune-Albright syndrome (MAS) is a rare disease caused by somatic postzygotic mutations at Arg201 in the GNAS1 gene that encodes for the Gsalpha protein. Arg201 mutations are gain-of-function mutations in affected tissues (including bone, skin, endocrine glands and other tissues) that result in the activation of cAMP. We used a polymerase chain reaction(PCR)-based technique for the selective enrichment and analysis of the Arg201 mutant allele in 27 different tissues from 24 Italian patients with one or more signs of MAS. Arg201 mutations were identified in 13 different tissues (48.1%) from 11 patients (45.8%). Mutation detection rates differed across the various types of tissue samples, and the mutation was not always found in every tissue sample from the same patient. To overcome problems in the analysis of mutations in somatic mosaicism, as occurs in MAS, a highly sensitive molecular technique should be applied, the most appropriate tissue source selected, and various affected tissues from the same patient analyzed.

    Journal of pediatric endocrinology & metabolism : JPEM 2002;15 Suppl 3;883-9

  • The DNA sequence and comparative analysis of human chromosome 20.

    Deloukas P, Matthews LH, Ashurst J, Burton J, Gilbert JG, Jones M, Stavrides G, Almeida JP, Babbage AK, Bagguley CL, Bailey J, Barlow KF, Bates KN, Beard LM, Beare DM, Beasley OP, Bird CP, Blakey SE, Bridgeman AM, Brown AJ, Buck D, Burrill W, Butler AP, Carder C, Carter NP, Chapman JC, Clamp M, Clark G, Clark LN, Clark SY, Clee CM, Clegg S, Cobley VE, Collier RE, Connor R, Corby NR, Coulson A, Coville GJ, Deadman R, Dhami P, Dunn M, Ellington AG, Frankland JA, Fraser A, French L, Garner P, Grafham DV, Griffiths C, Griffiths MN, Gwilliam R, Hall RE, Hammond S, Harley JL, Heath PD, Ho S, Holden JL, Howden PJ, Huckle E, Hunt AR, Hunt SE, Jekosch K, Johnson CM, Johnson D, Kay MP, Kimberley AM, King A, Knights A, Laird GK, Lawlor S, Lehvaslaiho MH, Leversha M, Lloyd C, Lloyd DM, Lovell JD, Marsh VL, Martin SL, McConnachie LJ, McLay K, McMurray AA, Milne S, Mistry D, Moore MJ, Mullikin JC, Nickerson T, Oliver K, Parker A, Patel R, Pearce TA, Peck AI, Phillimore BJ, Prathalingam SR, Plumb RW, Ramsay H, Rice CM, Ross MT, Scott CE, Sehra HK, Shownkeen R, Sims S, Skuce CD, Smith ML, Soderlund C, Steward CA, Sulston JE, Swann M, Sycamore N, Taylor R, Tee L, Thomas DW, Thorpe A, Tracey A, Tromans AC, Vaudin M, Wall M, Wallis JM, Whitehead SL, Whittaker P, Willey DL, Williams L, Williams SA, Wilming L, Wray PW, Hubbard T, Durbin RM, Bentley DR, Beck S and Rogers J

    The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK. panos@sanger.ac.uk

    The finished sequence of human chromosome 20 comprises 59,187,298 base pairs (bp) and represents 99.4% of the euchromatic DNA. A single contig of 26 megabases (Mb) spans the entire short arm, and five contigs separated by gaps totalling 320 kb span the long arm of this metacentric chromosome. An additional 234,339 bp of sequence has been determined within the pericentromeric region of the long arm. We annotated 727 genes and 168 pseudogenes in the sequence. About 64% of these genes have a 5' and a 3' untranslated region and a complete open reading frame. Comparative analysis of the sequence of chromosome 20 to whole-genome shotgun-sequence data of two other vertebrates, the mouse Mus musculus and the puffer fish Tetraodon nigroviridis, provides an independent measure of the efficiency of gene annotation, and indicates that this analysis may account for more than 95% of all coding exons and almost all genes.

    Nature 2001;414;6866;865-71

  • RGS-PX1, a GAP for GalphaS and sorting nexin in vesicular trafficking.

    Zheng B, Ma YC, Ostrom RS, Lavoie C, Gill GN, Insel PA, Huang XY and Farquhar MG

    Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093-0651, USA.

    Heterotrimeric GTP-binding proteins (G proteins) control cellular functions by transducing signals from the outside to the inside of cells. Regulator of G protein signaling (RGS) proteins are key modulators of the amplitude and duration of G protein-mediated signaling through their ability to serve as guanosine triphosphatase-activating proteins (GAPs). We have identified RGS-PX1, a Galpha(s)-specific GAP. The RGS domain of RGS-PX1 specifically interacted with Galpha(s), accelerated its GTP hydrolysis, and attenuated Galpha(s)-mediated signaling. RGS-PX1 also contains a Phox (PX) domain that resembles those in sorting nexin (SNX) proteins. Expression of RGS-PX1 delayed lysosomal degradation of the EGF receptor. Because of its bifunctional role as both a GAP and a SNX, RGS-PX1 may link heterotrimeric G protein signaling and vesicular trafficking.

    Funded by: NCI NIH HHS: CA58689; NHLBI NIH HHS: HL53773, HL63885; NIA NIH HHS: AG14563; NIDDK NIH HHS: DK17780; NIGMS NIH HHS: GM56904

    Science (New York, N.Y.) 2001;294;5548;1939-42

  • Multiplicity of mechanisms of serotonin receptor signal transduction.

    Raymond JR, Mukhin YV, Gelasco A, Turner J, Collinsworth G, Gettys TW, Grewal JS and Garnovskaya MN

    The Research Service of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29401, USA. raymondj@musc.edu

    The serotonin (5-hydroxytryptamine, 5-HT) receptors have been divided into 7 subfamilies by convention, 6 of which include 13 different genes for G-protein-coupled receptors. Those subfamilies have been characterized by overlapping pharmacological properties, amino acid sequences, gene organization, and second messenger coupling pathways. Post-genomic modifications, such as alternative mRNA splicing or mRNA editing, creates at least 20 more G-protein-coupled 5-HT receptors, such that there are at least 30 distinct 5-HT receptors that signal through G-proteins. This review will focus on what is known about the signaling linkages of the G-protein-linked 5-HT receptors, and will highlight some fascinating new insights into 5-HT receptor signaling.

    Funded by: NIDDK NIH HHS: DK02694, DK053981, DK52448, DK54720

    Pharmacology & therapeutics 2001;92;2-3;179-212

  • Analysis of the GNAS1 gene in Albright's hereditary osteodystrophy.

    Ahrens W, Hiort O, Staedt P, Kirschner T, Marschke C and Kruse K

    Department of Pediatrics, Medical University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany. ahrens@paedia.ukl.mu-luebeck.de

    Albright's hereditary osteodystrophy (AHO) is characterized by phenotypic signs that typically include brachydactyly and sc calcifications occurring with or without hormone resistance toward PTH or other hormones such as thyroid hormone or gonadotropins. Different inactivating mutations of the gene GNAS1 encoding Gsalpha lead to a reduced Gsalpha protein activity in patients with AHO and pseudohypoparathyroidism type Ia or without resistance to PTH (pseudopseudohypoparathyroidism). We investigated 29 unrelated patients with AHO and pseudohypoparathyroidism type Ia or pseudopseudohypoparathyroidism and their affected family members performing functional and molecular genetic analysis of Gsalpha. In vitro determination of Gsalpha protein activity in erythrocyte membranes was followed by the investigation of the whole coding region of the GNAS1 gene using PCR, nonisotopic single strand conformation analysis, and direct sequencing of the PCR products. All patients showed a reduced Gsalpha protein activity (mean 59% compared with healthy controls). In 21/29 (72%) patients, 15 different mutations in GNAS1 including 11 novel mutations were detected. In addition we add five unrelated patients with a previously described 4 bp deletion in exon 7 (Delta GACT, codon 189/190), confirming the presence of a hot spot for loss of function mutations in GNAS1. In eight patients, no molecular abnormality was found in the GNAS1 gene despite a functional defect of Gsalpha. We conclude that biochemical and molecular analysis of Gsalpha and its gene GNAS1 can be valuable tools to confirm the diagnosis of AHO. However, in some patients with reduced activity of Gsalpha, the molecular defect cannot be detected in the exons encoding the common form of Gsalpha.

    The Journal of clinical endocrinology and metabolism 2001;86;10;4630-4

  • Expression profiling of cardiac genes in human hypertrophic cardiomyopathy: insight into the pathogenesis of phenotypes.

    Lim DS, Roberts R and Marian AJ

    Section of Cardiology, Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA.

    Objectives: The goal of this study was to identify genes upregulated in the heart in human patients with hypertrophic cardiomyopathy (HCM).

    Background: Hypertrophic cardiomyopathy is a genetic disease caused by mutations in contractile sarcomeric proteins. The molecular basis of diverse clinical and pathologic phenotypes in HCM remains unknown.

    Methods: We performed polymerase chain reaction-select complementary DNA subtraction between normal hearts and hearts with HCM and screened subtracted libraries by Southern blotting. We sequenced the differentially expressed clones and performed Northern blotting to detect increased expression levels.

    Results: We screened 288 independent clones, and 76 clones had less than twofold increase in the signal intensity and were considered upregulated. Sequence analysis identified 36 genes including those encoding the markers of pressure overload-induced ("secondary") cardiac hypertrophy, cytoskeletal proteins, protein synthesis, redox system, ion channels and those with unknown function. Northern blotting confirmed increased expression of skeletal muscle alpha-actin (ACTA1), myosin light chain 2a (MLC2a), GTP-binding protein Gs-alpha subunit (GNAS1), NADH ubiquinone oxidoreductase (NDUFB10), voltage-dependent anion channel 1 (VDAC1), four-and-a-half LIM domain protein 1 (FHL1) (also known as SLIM1), sarcosin (SARCOSIN) and heat shock 70kD protein 8 (HSPA8) by less than twofold. Expression levels of ACTA1, MLC2a and GNAS1 were increased in six additional and FHL1 in four additional hearts with HCM.

    Conclusions: A diverse array of genes is upregulated in the heart in human patients with HCM, which could account for the diversity of clinical and pathologic phenotypes. Markers of secondary hypertrophy are also upregulated, suggesting commonality of pathways involved in HCM and the acquired forms of cardiac hypertrophy. Elucidation of the role of differentially expressed genes in HCM could provide for new therapeutic targets.

    Funded by: NHLBI NIH HHS: P50 HL054313, P50 HL054313-060012, P50 HL054313-070012, P50 HL054313-080012, P50 HL054313-08S10012, P50 HL054313-090012, P50 HL054313-100012, P50-HL42267-01, R01 HL068884, R01 HL068884-01

    Journal of the American College of Cardiology 2001;38;4;1175-80

  • Galphas transcripts are biallelically expressed in the human kidney cortex: implications for pseudohypoparathyroidism type 1b.

    Zheng H, Radeva G, McCann JA, Hendy GN and Goodyer CG

    Department of Pediatrics, McGill University, Montréal, Québec, Canada H3Z 2Z3.

    Pseudohypoparathyroid type 1b patients are characterized by renal resistance to PTH in the absence of Albright's hereditary osteodystrophy or other endocrine abnormalities. Kindred studies have suggested that the cause of this resistance is a specific decrease in Galphas activity in renal proximal tubules due to paternal imprinting of Galphas. To test this, allelic expression of Galphas was analyzed in human fetal kidney cortex samples by RT-PCR assays. The results showed that, in contrast to the parent-specific expression of exon 1A and XLalphas (paternal) or NESP (maternal) mRNAs, Galphas transcripts are biallelically expressed in human kidney cortex. These data implicate abnormal imprinting of alternative regions within the GNAS1 locus as a more likely cause of pseudohypoparathyroid type 1b.

    The Journal of clinical endocrinology and metabolism 2001;86;10;4627-9

  • Genetic variation of the extra-large stimulatory G protein alpha-subunit leads to Gs hyperfunction in platelets and is a risk factor for bleeding.

    Freson K, Hoylaerts MF, Jaeken J, Eyssen M, Arnout J, Vermylen J and Van Geet C

    Center for Molecular and Vascular Biology, University Hospital Gasthuisberg, University of Leuven, Belgium.

    Alternatively spliced GNAS1 and XL-GNAS1, encoding respectively the stimulatory G-protein alpha-subunit (Gsalpha) and the extra-large stimulatory G-protein alpha-subunit (XLsalpha), are located on the imprinted chromosomal region 20q13.12-13. We presently report a functional polymorphism in the imprinted XL-GNAS1 gene. In three patients, a 36 bp insertion and two basepair substitutions flanking this insertion were found in the paternally inherited XL-GNAS1 exon 1. They clinically manifest an enhanced trauma-related bleeding tendency and a variable degree of mental retardation. A platelet aggregation inhibition test to evaluate Gs function was developed. Their platelets display Gs hyperfunction and an enhanced cAMP generation upon stimulation of Gs-coupled receptors. The prevalence of the XLsalpha insertion in a normal control group was 2.2%. Normal controls, inheriting the insertion maternally, had a normal platelet Gs activity, whereas controls inheriting the insertion paternally had increased inducible platelet Gs activity, defining the insertion as a functional polymorphism. This paternally inherited XLsalpha insertion represents a new genetic cause of an inherited bleeding tendency, although to a variable degree.

    Thrombosis and haemostasis 2001;86;3;733-8

  • Two overlapping reading frames in a single exon encode interacting proteins--a novel way of gene usage.

    Klemke M, Kehlenbach RH and Huttner WB

    Department of Neurobiology, Interdisciplinary Centre of Neuroscience, University of Heidelberg, Im Neuenheimer Feld 364, D-69120 Heidelberg, Germany.

    The >1 kb XL-exon of the rat XLalphas/Galphas gene encodes the 37 kDa XL-domain, the N-terminal half of the 78 kDa neuroendocrine-specific G-protein alpha-subunit XLalphas. Here, we describe a novel feature of the XL-exon, the presence of an alternative >1 kb open reading frame (ORF) that completely overlaps with the ORF encoding the XL-domain. The alternative ORF starts 32 nucleotides downstream of the start codon for the XL-domain and is terminated by a stop codon exactly at the end of the XL-exon. The alternative ORF encodes ALEX, a very basic (pI 11.8), proline-rich protein of 356 amino acids. Both XLalphas and ALEX are translated from the same mRNA. Like XLalphas, ALEX is expressed in neuroendocrine cells and tightly associated with the cytoplasmic leaflet of the plasma membrane. Remarkably, ALEX binds to the XL-domain of XLalphas. Our results reveal a mechanism of gene usage that is without precedent in mammalian genomes.

    The EMBO journal 2001;20;14;3849-60

  • Gbeta gamma isoforms selectively rescue plasma membrane localization and palmitoylation of mutant Galphas and Galphaq.

    Evanko DS, Thiyagarajan MM, Siderovski DP and Wedegaertner PB

    Department of Microbiology and Immunology and Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.

    Mutation of Galpha(q) or Galpha(s) N-terminal contact sites for Gbetagamma resulted in alpha subunits that failed to localize at the plasma membrane or undergo palmitoylation when expressed in HEK293 cells. We now show that overexpression of specific betagamma subunits can recover plasma membrane localization and palmitoylation of the betagamma-binding-deficient mutants of alpha(s) or alpha(q). Thus, the betagamma-binding-defective alpha is completely dependent on co-expression of exogenous betagamma for proper membrane localization. In this report, we examined the ability of beta(1-5) in combination with gamma(2) or gamma(3) to promote proper localization and palmitoylation of mutant alpha(s) or alpha(q). Immunofluorescence localization, cellular fractionation, and palmitate labeling revealed distinct subtype-specific differences in betagamma interactions with alpha subunits. These studies demonstrate that 1) alpha and betagamma reciprocally promote the plasma membrane targeting of the other subunit; 2) beta(5), when co-expressed with gamma(2) or gamma(3), fails to localize to the plasma membrane or promote plasma membrane localization of mutant alpha(s) or alpha(q); 3) beta(3) is deficient in promoting plasma membrane localization of mutant alpha(s) and alpha(q), whereas beta(4) is deficient in promoting plasma membrane localization of mutant alpha(q); 4) both palmitoylation and interactions with betagamma are required for plasma membrane localization of alpha.

    Funded by: NIGMS NIH HHS: GM56444

    The Journal of biological chemistry 2001;276;26;23945-53

  • Macroorchidism due to autonomous hyperfunction of Sertoli cells and G(s)alpha gene mutation: an unusual expression of McCune-Albright syndrome in a prepubertal boy.

    Coutant R, Lumbroso S, Rey R, Lahlou N, Venara M, Rouleau S, Sultan C and Limal JM

    Département de Pédiatrie, Centre Hospitalier Universitaire, 49000 Angers, France. recoutant@chu-angers.fr

    We report an unusual observation of a 3.8-yr-old boy with McCune-Albright syndrome (MAS) associated with abnormal prepubertal testis enlargement and no sexual precocity. Physical examination showed café-au-lait skin lesions, enlarged testes, prepubertal sized penis, and no pubic or axillary hair. Skeletal radiography disclosed fibrous dysplasia. The serum testosterone level was 0.58 nmol/L and remained below 1.4 nmol/L during the 4-yr follow-up. By contrast, serum inhibin B and anti-Mullerian hormone concentrations were abnormally increased up to 255 pg/mL (childhood range, 35--180) and 792 pmol/L (childhood range, 309--566), respectively. The LH response to a GnRH test was in the prepubertal range, whereas the FSH response was blunted. This abnormal hormone concentration profile indicates autonomous hyperfunction of Sertoli cells, with no evidence of Leydig cell activation. Testicular histology showed tubules with marked Sertoli cell hyperplasia and very rare germinal cells, and interstitial tissue containing mesenchymal cells but no mature Leydig cells. DNA sequence analysis from bone and testis tissues detected the known activating mutation in MAS that results in replacement of Arg by His at codon 201 of the G(s)alpha protein. Other endocrine tests showed excessive GH secretion and moderate adrenal androgen hypersecretion. These findings are consistent with the occurrence of an activating mutation of the G(s)alpha gene mainly expressed in Sertoli cells and weakly expressed or absent in Leydig cells. Abnormal prepubertal testicular enlargement extends the clinical spectrum of MAS, suggesting that determination of serum inhibin B and anti-Mullerian hormone should be considered in boys with this syndrome. This observation demonstrates the usefulness of detailed molecular and biological investigations in atypical cases of MAS.

    The Journal of clinical endocrinology and metabolism 2001;86;4;1778-81

  • Mazabraud syndrome in two patients: clinical overlap with McCune-Albright syndrome.

    Faivre L, Nivelon-Chevallier A, Kottler ML, Robinet C, Khau Van Kien P, Lorcerie B, Munnich A, Maroteaux P, Cormier-Daire V and LeMerrer M

    Centre de Génétique, Hôpital d'Enfants, Dijon, France.

    Mazabraud syndrome is a rare sporadic disorder, mainly characterized by bone fibrous dysplasia and intramuscular myxomas. We report here two new cases of Mazabraud syndrome. One of our patients (Patient 1) also had café-au-lait spots and multinodular goiter suggestive of McCune-Albright syndrome. We review the 37 previously reported cases with Mazabraud syndrome and discuss the 6/37 patients with criteria of Mazabraud and McCune-Albright syndromes. Based on the clinical overlap between the two syndromes, we tested the GNAS1 gene in blood leukocytes and skin fibroblasts of Patient 1, but found no evidence of an activating mutation in the GNAS1 gene.

    American journal of medical genetics 2001;99;2;132-6

  • Two mutations of the Gsalpha gene in two Japanese patients with sporadic pseudohypoparathyroidism type Ia.

    Ishikawa Y, Tajima T, Nakae J, Nagashima T, Satoh K, Okuhara K and Fujieda K

    Department of Pediatrics, Kushiro Red Cross Hospital, Japan.

    Pseudohypoparathyroidism Ia (PHP-Ia), is an inherited disease with clinical hypoparathyroidism caused by parathyroid hormone resistance (PTH), and shows the phenotype of Albright hereditary osteodystrophy (AHO), including short stature, obesity, round face, brachydactyly, and subcutaneous ossification. This disease is caused by mutation that inactivates the alpha-subunit of Gs, the stimulatory regulator of adenylyl cyclase. Here, a novel frameshift mutation (delG at codon 88) in exon 4, and a missense mutation (R231H) in exon 9 of the Gsalpha gene were identified in two Japanese patients with sporadic PHP-Ia. Deletion of a G in exon 4 at codon 88 in the first patient produced a premature stop codon, resulting in the truncated protein. The second patient had a previously reported R231H mutation. Because this amino acid is located in a region, switch 2, that is thought to interact with the betagamma subunit of Gsalpha protein, this mutation may impair Gs protein function. We report here one novel Gsalpha mutation, and note that mutations in Japanese patients with PHP-Ia are probably heterogeneous.

    Journal of human genetics 2001;46;7;426-30

  • Mutational analysis of GNAS1 in patients with pseudohypoparathyroidism: identification of two novel mutations.

    Mantovani G, Romoli R, Weber G, Brunelli V, De Menis E, Beccio S, Beck-Peccoz P and Spada A

    Ospedale Maggiore IRCCS, Institute of Endocrine Sciences, University of Milan, Italy.

    Pseudohypoparathyroidism (PHP) refers to two major variants that generally coexist in the same family, PHP type Ia (PHP Ia), in which both PTH resistance and a constellation of physical features, termed Albright's hereditary osteodystrophy (AHO), are present, and pseudopseudohypoparathyroidism (PPHP), in which AHO occurs without PTH resistance. Most patients with PHP Ia show a partial deficiency (50%) of Gs activity, due to loss of function mutations in Gsalpha gene (GNAS1). The present study reports clinical, biochemical, and molecular data of 8 unrelated families with PHP Ia and PPHP. The 13 exons of GNAS1 were screened for mutations by PCR and direct sequencing of the amplified products. We detected heterozygous mutations in the affected members of the 4 families in which PHP Ia was present. In 2 families 2 previously reported deletions in exons 5 and 7 were found, whereas in the other 2 families, 2 novel frameshift deletions were identified in exons 1 and 11, causing a premature stop codon in the mutant allele. No mutation was detected in the families in which PPHP was the only clinical manifestation. In conclusion, we report the first mutational analysis of Italian patients with PHP Ia and PPHP, and we describe two novel deletions in GNAS1. Furthermore, we confirm that these mutations cannot be detected in families with isolated PPHP, suggesting that these forms of AHO are genetically distinct from PHP Ia.

    The Journal of clinical endocrinology and metabolism 2000;85;11;4243-8

  • Characterization of the extra-large G protein alpha-subunit XLalphas. II. Signal transduction properties.

    Klemke M, Pasolli HA, Kehlenbach RH, Offermanns S, Schultz G and Huttner WB

    Department of Neurobiology, University of Heidelberg, Im Neuenheimer Feld 364, D-69120 Heidelberg, Germany.

    In the preceding paper (Pasolli, H. A., Klemke, M., Kehlenbach, R. H. , Wang, Y., and Huttner, W. B. (2000) J. Biol. Chem. 275, 33622-33632), we report on the tissue distribution and subcellular localization of XLalphas (extra large alphas), a neuroendocrine-specific, plasma membrane-associated protein consisting of a novel 37-kDa XL domain followed by a 41-kDa alphas domain encoded by exons 2-13 of the Galphas gene. Here, we have studied the signal transduction properties of XLalphas. Like Galphas, XLalphas undergoes a conformational change upon binding of GTPgammaS (guanosine 5'-O-(thio)triphosphate), as revealed by its partial resistance to tryptic digestion, which generated the same fragments as in the case of Galphas. Two approaches were used to analyze XLalphas-betagamma interactions: (i) ADP-ribosylation by cholera toxin to detect even weak or transient XLalphas-betagamma interaction 606 s and (ii) sucrose density gradient centrifugation to reveal stable heterotrimer formation. The addition of betagamma subunits resulted in an increased ADP-ribosylation of XLalphas as well as an increased sedimentation rate of XLalphas in sucrose density gradients, indicating that XLalphas interacts with the betagamma dimer. Surprisingly, however, XLalphas, in contrast to Galphas, was not activated by the beta2-adrenergic receptor upon reconstitution of S49cyc(-) membranes. Similarly, using photoaffinity labeling of pituitary membranes with azidoanilide-GTP, XLalphas was not activated upon stimulation of pituitary adenylyl cyclase-activating polypeptide (PACAP) receptors or other Galphas-coupled receptors known to be present in these membranes, whereas Galphas was. Despite the apparent inability of XLalphas to undergo receptor-mediated activation, XLalphas-GTPgammaS markedly stimulated adenylyl cyclase in S49cyc(-) membranes. Moreover, transfection of PC12 cells with a GTPase-deficient mutant of XLalphas, XLalphas-Q548L, resulted in a massive increase in adenylyl cyclase activity. Our results suggest that in neuroendocrine cells, the two related G proteins, Galphas and XLalphas, exhibit distinct properties with regard to receptor-mediated activation but converge onto the same effector system, adenylyl cyclase.

    The Journal of biological chemistry 2000;275;43;33633-40

  • Systematic subcellular localization of novel proteins identified by large-scale cDNA sequencing.

    Simpson JC, Wellenreuther R, Poustka A, Pepperkok R and Wiemann S

    Department of Cell Biology and Biophysics, EMBL Heidelberg, Germany.

    As a first step towards a more comprehensive functional characterization of cDNAs than bioinformatic analysis, which can only make functional predictions for about half of the cDNAs sequenced, we have developed and tested a strategy that allows their systematic and fast subcellular localization. We have used a novel cloning technology to rapidly generate N- and C-terminal green fluorescent protein fusions of cDNAs to examine the intracellular localizations of > 100 expressed fusion proteins in living cells. The entire analysis is suitable for automation, which will be important for scaling up throughput. For > 80% of these new proteins a clear intracellular localization to known structures or organelles could be determined. For the cDNAs where bioinformatic analyses were able to predict possible identities, the localization was able to support these predictions in 75% of cases. For those cDNAs where no homologies could be predicted, the localization data represent the first information.

    EMBO reports 2000;1;3;287-92

  • An imprinted antisense transcript at the human GNAS1 locus.

    Hayward BE and Bonthron DT

    Molecular Medicine Unit, University of Leeds, Clinical Sciences Building, St James's University Hospital, Leeds LS9 7TF, UK.

    Recent studies of the GNAS1 gene have shown a highly complex imprinted expression pattern, with paternally, maternally and biallelically derived protein products, raising questions regarding how such transcriptional complexity is established and maintained. GNAS1 was originally identified as the gene encoding an important and widely expressed signal transduction protein, the alpha subunit of the stimulatory G protein G(s). Partial G(s)alpha deficiency results in the hormone resistance syndrome, pseudohypoparathyroidism type 1a. G(s)alpha is encoded by exons 1-13 of GNAS1 and, in most tissues at least, expression of this transcript is biallelic. Two large upstream exons, however, have monoallelic expression patterns, and in each case their transcripts splice onto GNAS1 exon 2. The most 5' of these is maternally expressed, and encodes neuroendocrine secretory protein 55 (NESP55), whose coding region does not overlap with that of G(s)alpha. The other exon, 14 kb further 3', is paternally expressed, and encodes XL(alpha)s (extra large alphas-like protein), translated in-frame with G(s)alpha exons 2-13. This close proxi b50 mity of two oppositely imprinted promoters suggested the likelihood of important regulatory interactions between them, and to investigate this possibility we have performed a search for other transcripts in the region. Here we show that the maternally methylated region upstream of the XL(alpha)s exon gives rise to a spliced polyadenylated antisense transcript, which spans the upstream NESP55 region. This antisense transcript is imprinted, and expressed only from the paternal allele, suggesting that it may have a specific role in suppressing in cis the activity of the paternal NESP55 allele.

    Human molecular genetics 2000;9;5;835-41

  • Neuroendocrine secretory protein 55 (NESP55): alternative splicing onto transcripts of the GNAS gene and posttranslational processing of a maternally expressed protein.

    Weiss U, Ischia R, Eder S, Lovisetti-Scamihorn P, Bauer R and Fischer-Colbrie R

    Department of Pharmacology, University of Innsbruck, Austria.

    Recent studies established a novel genomically imprinted gene located 45 kb upstream of the human GNAS1 locus. This locus encoded for the Neuroendocrine Secretory Protein with an apparent molecular weight of 55,000 (NESP55), which is transcribed exclusively from the maternal allele. We sequenced rat and human NESP55 and investigated tissue-specific splicing of its mRNA and posttranslational modifications of the protein in various tissues. Alternative mRNA splicing of NESP55 was analyzed by sequencing of cDNA clones, RT-PCR and Northern blotting. Two main splice variants, which were generated in a tissue-specific manner, were identified: The open reading frame encoding NESP55 was spliced onto exons 2-13 of Gsalpha in the adrenal medulla, pituitary and the brain. In addition, in the pituitary a second shorter, prominent mRNA transcript was generated by splicing of NESP55 onto exons 2, 3 and N1 of Gsalpha. Several of the cDNA clones isolated contained inverted repeats of 50-150 bp at their 5' or 3' termini, which might form hairpin stems and thus alter mRNA stability. The NESP55 open reading frame encoded a hydrophilic protein of 28,018 Da (human) and 29,218 Da (rat), respectively, which resembled the class of acidic, neuroendocrine secretory proteins collectively called chromogranins. NESP55 is highly conserved among mammalian species. It is posttranslationally acidified by the addition of keratan sulfate glycosaminoglycan chains and differentially processed by endopeptidases in various endocrine and neuronal tissues.

    Neuroendocrinology 2000;71;3;177-86

  • PHR1 encodes an abundant, pleckstrin homology domain-containing integral membrane protein in the photoreceptor outer segments.

    Xu S, Ladak R, Swanson DA, Soltyk A, Sun H, Ploder L, Vidgen D, Duncan AM, Garami E, Valle D and McInnes RR

    Predoctoral Training Program in Human Genetics, Department of Pediatrics, Baltimore, Maryland 21205, USA.

    We cloned human and murine cDNAs of a gene (designated PHR1), expressed preferentially in retina and brain. In both species, PHR1 utilizes two promoters and alternative splicing to produce four PHR1 transcripts, encoding isoforms of 243, 224, 208, and 189 amino acids, each with a pleckstrin homology domain at their N terminus and a transmembrane domain at their C terminus. Transcript 1 originates from a 5'-photoreceptor-specific promoter with at least three Crx elements ((C/T)TAATCC). Transcript 2 originates from the same promoter but lacks exon 7, which encodes 35 amino acids immediately C-terminal to the pleckstrin homology domain. Transcripts 3 and 4 originate from an internal promoter in intron 2 and either include or lack exon 7, respectively. In situ hybridization shows that PHR1 is highly expressed in photoreceptors, with lower expression in retinal ganglion cells. Immunohistochemistry localizes the PHR1 protein to photoreceptor outer segments where chemical extraction studies confirm it is an integral membrane protein. Using a series of PHR1 glutathione S-transferase fusion proteins to perform in vitro binding assays, we found PHR1 binds transducin betagamma subunits but not inositol phosphates. This activity and subcellular location suggests that PHR1 may function as a 1b09 previously unrecognized modulator of the phototransduction pathway.

    The Journal of biological chemistry 1999;274;50;35676-85

  • A novel spliced variant of the type 1 corticotropin-releasing hormone receptor with a deletion in the seventh transmembrane domain present in the human pregnant term myometrium and fetal membranes.

    Grammatopoulos DK, Dai Y, Randeva HS, Levine MA, Karteris E, Easton AJ and Hillhouse EW

    Sir Quinton Hazell Molecular Medicine Research Centre, Department of Biological Sciences, University of Warwick, Coventry, United Kingdom. chdg@dna.bio.warwick.ac.uk

    CRH exerts its actions via activation of specific G protein-coupled receptors, which exist in two types, CRH-R1 and CRH-R2, and arise from different genes with multiple spliced variants. RT-PCR amplification of CRH receptor sequences from human myometrium and fetal membranes yielded cDNAs that encode a novel CRH-R type 1 spliced variant. This variant (CRH-R1d) is present in the human pregnant myometrium at term only, which suggests a physiologically important role at the end of human pregnancy and labor. The amino acid sequence of CRH-R1d is identical to the CRH-R1alpha receptor except that it contains an exon deletion resulting in the absence of 14 amino acids in the predicted seventh transmembrane domain. Binding studies in HEK-293 cells stably expressing the CRH-R1d or CRH-R1alpha receptors revealed that the deletion does not change the binding characteristics of the variant receptor. In contrast, studies on the G protein activation demonstrated that CRH-R1d is not well coupled to the four subtypes of G proteins (G(s), G(i), G(o), G(q)) that CRH-R1alpha can activate. These data suggest that although the deleted segment is not important for CRH binding, it plays a crucial role in CRH receptor signal transduction. Second messenger studies of the variant receptor showed that CRH and CRH-like peptides can stimulate the adenylate cyclase system, with reduced sensitivity and potency by 10-fold compared with the CRH-R1alpha. Furthermore, CRH failed to stimulate inositol trisphosphate production. Coexpression studies between the CRH-R1d or CRH-R1alpha showed that this receptor does not play a role as a dominant negative receptor for CRH.

    Funded by: Wellcome Trust

    Molecular endocrinology (Baltimore, Md.) 1999;13;12;2189-202

  • A novel GNAS1 mutation, R201G, in McCune-albright syndrome.

    Riminucci M, Fisher LW, Majolagbe A, Corsi A, Lala R, De Sanctis C, Robey PG and Bianco P

    Dipartimento di Medicina Sperimentale, Universitá dell'Aquila, L'Aquila, Italy.

    Funded by: Telethon: E.1029

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 1999;14;11;1987-9

  • Kinetics of ternary complex formation with fusion proteins composed of the A(1)-adenosine receptor and G protein alpha-subunits.

    Waldhoer M, Wise A, Milligan G, Freissmuth M and Nanoff C

    Institute of Pharmacology, University of Vienna, Währinger Strasse 13a, A-1090 Vienna, Austria.

    High affinity agonist binding to G protein-coupled receptors depends on the formation of a ternary complex between agonist, receptor, and G protein. This process is too slow to be accounted for by a simple diffusion-controlled mechanism. We have tested if the interaction between activated receptor and G protein is rate-limiting by fusing the coding sequence of the human A(1)-adenosine receptor to that of Galpha(i-1) (A(1)/Galpha(i-1)) and of Galpha(o) (A(1)/Galpha(o)). Fusion proteins of the expected molecular mass were detected following transfection of HEK293 cells. Ternary complex formation was monitored by determining the kinetics for binding of the high affinity agonist (-)-N(6)-3[(125)I](iodo-4-hydroxyphenylisopropyl)adenosine; these were similar in the wild-type receptor and the fusion proteins over the temperature range of 10 to 30 degrees C. Agonist dissociation may be limited by the stability of the ternary complex. This assumption was tested by creating fusion proteins in which the Cys(351) of Galpha(i-1) was replaced with glycine (A(1)/Galpha(i-1)C351G) or isoleucine (A(1)/Galpha(i-1)C351I) to lower the affinity of the receptor for the G protein. In these mutated fusion proteins, the dissociation rate of the ternary complex was accelerated; in contrast, the rate of the forward reaction was not affected. We therefore conclude that (i) receptor activation per se rather than its interaction with the G protein is rate-limiting in ternary complex formation; (ii) the stability of the ternary complex is determined by the dissociation rate of the G protein. These features provide for a kinetic proofreading mechanism that sustains the fidelity of receptor-G protein coupling.

    The Journal of biological chemistry 1999;274;43;30571-9

  • The luteinizing hormone receptor activates phospholipase C via preferential coupling to Gi2.

    Kühn B and Gudermann T

    Institut für Pharmakologie, Freie Universität Berlin, Germany.

    Binding of lutropin/choriogonadotropin (LH/CG) to its cognate receptor results in the activation of adenylyl cyclase and phospholipase C. This divergent signaling of the LH receptor is based on the independent activation of distinct G protein subfamilies, i.e. , Gs, Gi, and potentially also Gq. To examine the selectivity of LH receptor coupling to phospholipase C beta-activating G proteins, we used an in vivo reconstitution system based on the coexpression of the LH receptor and different G proteins in baculovirus-infected insect cells. In this paper, we describe a refined expression strategy for the LH receptor in insect cells. The receptor protein was inserted into the cell membrane at an expression level of 0.8 pmol/mg of membrane protein. Sf9 cells expressing the LH receptor responded to hCG challenge with a concentration-dependent accumulation of intracellular cAMP (EC50 = 630 nM) but not of inositol phosphates, whereas stimulation of the histamine H1 receptor in Sf9 cells led to increased phospholipase C (PLC) activity. Immunoblotting experiments using G protein-specific antisera revealed the absence of quantitative amounts of alpha i in Sf9 cells, whereas alpha s and alpha q/11 were detected. We therefore attempted to restore the hCG-dependent PLC activation by infection of Sf9 cells with viruses encoding the LH receptor and different G protein alpha subunits. HCG stimulation of cells coexpressing the LH receptor and exogenous alpha i2 resulted in stimulation of PLC activity. In cells coinfected with an alpha i3-baculovirus, hCG challenge led to a minor activation of PLC, whereas no hCG-dependent PLC stimulation was observed in cells coexpressing alpha i1. Most notably, coinfection with baculoviruses encoding alpha q or alpha 11 did not reproduce the PLC activation by the LH receptor. Thus, the murine LH receptor activates adenylyl cyclase via Gs and PLC via selective coupling to Gi2.

    Biochemistry 1999;38;38;12490-8

  • Identification of two novel deletion mutations within the Gs alpha gene (GNAS1) in Albright hereditary osteodystrophy.

    Yu D, Yu S, Schuster V, Kruse K, Clericuzio CL and Weinstein LS

    Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

    Albright hereditary osteodystrophy (AHO) is a genetic disorder characterized by short stature, skeletal defects, and obesity. Within AHO kindreds, some affected family members have only the somatic features of AHO [pseudopseudohypoparathyroidism (PPHP)], whereas others have these features in association with resistance to multiple hormones that stimulate adenylyl cyclase within their target tissues [pseudohypoparathyroidism type Ia (PHP Ia)]. Affected members of most AHO kindreds (both those with PPHP and those with PHP Ia) have a partial deficiency of Gs alpha, the alpha-subunit of the G protein that couples receptors to adenylyl cyclase stimulation, and in a number of cases heterozygous loss of function mutations within the Gs alpha gene (GNAS1) have been identified. Using PCR with the attachment of a high melting domain (GC-clamp) and temperature gradient gel electrophoresis, two novel heterozygous frameshift mutations within GNAS1 were found in two AHO kindreds. In one kindred all affected members (both PHP Ia and PPHP) had a heterozygous 2-bp deletion in exon 8, whereas in the second kindred a heterozygous 2-bp deletion in exon 4 was identified in all affected members examined. In both cases the frameshift encoded a premature termination codon several codons downstream of the deletion. In the latter kindred affected members were previously shown to have decreased levels of GNAS1 messenger ribonucleic acid expression. These results further underscore the genetic heterogeneity of AHO and provides further evidence that PHP Ia and PPHP are two clinical presentations of a common genetic defect. Serial measurements of thyroid function in members of kindred 1 indicate that TSH resistance progresses with age and becomes more evident after the first year of life.

    The Journal of clinical endocrinology and metabolism 1999;84;9;3254-9

  • A mutation in the heterotrimeric stimulatory guanine nucleotide binding protein alpha-subunit with impaired receptor-mediated activation because of elevated GTPase activity.

    Warner DR and Weinstein LS

    Membrane Biochemistry Section, Laboratory of Molecular and Cellular Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA. dwarner@helix.nih.gov

    It has been reported that substitution of Arg258, a residue within the GTPase domain of the heterotrimeric guanine nucleotide binding protein (G protein) alpha-subunit (alphas), to alanine (alphas-R258A) results in decreased activation by receptor or aluminum fluoride (AlF4-) and increased basal GDP release. Arg258 interacts with Gln170 in the helical domain, and, presumably, loss of this interaction between the GTPase and helical domain leads to more rapid GDP release, resulting in decreased activation by AlF4- and increased thermolability. In this study, we mutate Gln170 to alanine (alphas-Q170A) and demonstrate that this mutant, like alphas-R258A, has decreased activation by AlF4-, increased thermolability (both reversed in the presence of excess guanine nucleotide), and an increased rate of GDP release. However, unlike alphas-R258A, alphas-Q170A does not have impaired receptor-mediated activation. Therefore, this interdomain interaction is critical to maintain normal guanine nucleotide binding (and hence normal activation by AlF4-) but is not important for receptor-mediated activation. In single turnover GTPase assays, the catalytic rate for GTP hydrolysis of alphas-R258A was 14-fold higher than normal whereas that of alphas-Q170A was unaffected. Examination of the alphas crystal structure suggests that Arg258, through interactions with Glu50, might constrain the position of Arg201, a residue critical for catalyzing the GTPase reaction. This is an example of a mutation in a heterotrimeric G protein that results in an increased intrinsic GTPase activity and provides another mechanism by which G protein mutations can impair signal transduction.

    Proceedings of the National Academy of Sciences of the United States of America 1999;96;8;4268-72

  • McCune-Albright syndrome: clinical and molecular evidence of mosaicism in an unusual giant patient.

    Tinschert S, Gerl H, Gewies A, Jung HP and Nürnberg P

    Institut für Medizinische Genetik, Universitäsklinikum Charité, Humboldt-Universität zu Berlin, Germany.

    Molecular genetics recently uncovered the mystery of the protean picture of McCune-Albright syndrome by identification of the somatic gain of function mutations in the GNAS1 gene. Here we present an adult patient with fibrous dysplasia and an endocrinopathy resulting in unusual giant height. The clinical diagnosis in the patient could be confirmed by molecular investigations in tissues involved in the process of fibrous dysplasia.

    American journal of medical genetics 1999;83;2;100-8

  • Bidirectional imprinting of a single gene: GNAS1 encodes maternally, paternally, and biallelically derived proteins.

    Hayward BE, Moran V, Strain L and Bonthron DT

    Human Genetics Unit, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom.

    The GNAS1 gene encodes the alpha subunit of the guanine nucleotide-binding protein Gs, which couples signaling through peptide hormone receptors to cAMP generation. GNAS1 mutations underlie the hormone resistance syndrome pseudohypoparathyroidism type Ia (PHP-Ia), so the maternal inheritance displayed by PHP-Ia has raised suspicions that GNAS1 is imprinted. Despite this suggestion, in most tissues Gsalpha is biallelically encoded. In contrast, the large G protein XLalphas, also encoded by GNAS1, is paternally derived. Because the inheritance of PHP-Ia predicts the existence of maternally, rather than paternally, expressed transcripts, we have investigated the allelic origin of other mRNAs derived from GNAS1. We find this gene to be remarkable in the complexity of its allele-specific regulation. Two upstream promoters, each associated with a large coding exon, lie only 11 kb apart, yet show opposite patterns of allele-specific methylation and monoallelic transcription. The more 5' of these exons encodes the neuroendocrine secretory protein NESP55, which is expressed exclusively from the maternal allele. The NESP55 exon is 11 kb 5' to the paternally expressed XLalphas exon. The transcripts from these two promoters both splice onto GNAS1 exon 2, yet share no coding sequences. Despite their structural unrelatedness, the encoded proteins, of opposite allelic origin, both have been implicated in regulated secretion in neuroendocrine tissues. Remarkably, maternally (NESP55), paternally (XLalphas), and biallelically (Gsalpha) derived proteins all are produced by different patterns of promoter use and alternative splicing of GNAS1, a gene showing simultaneous imprinting in both the paternal and maternal directions.

    Funded by: Wellcome Trust

    Proceedings of the National Academy of Sciences of the United States of America 1998;95;26;15475-80

  • Role of regulator of G protein signaling in desensitization of the glucose-dependent insulinotropic peptide receptor.

    Tseng CC and Zhang XY

    Section of Gastroenterology, Boston Veterans Administration Medical Center, and Boston University School of Medicine, Massachusetts 02118, USA.

    The glucose-dependent insulinotropic peptide receptor (GIP-R) is a member of the G protein-coupled receptors. Recent studies have indicated that elevated serum GIP concentrations in type II diabetic patients might induce desensitization of the GIP-R, and this mechanism could contribute to impaired insulin secretion. The cellular and molecular mechanisms governing GIP desensitization are unknown. Here, we report the results of studies on a new family of proteins known as regulators of G protein signaling (RGS) that have been shown to mediate the desensitization process of other receptors. GIP-R and RGS1, -2, -3, and -4 complementary DNAs were cotransfected into human embryonic kidney cells (L293). GIP-stimulated cAMP generation in control cells and in those coexpressing RGS1, -3, and -4 displayed a dose-dependent increase 10 min after GIP treatment. In contrast, RGS2 expression inhibited the GIP-induced cAMP response by 50%, a response similar to that of cells desensitized by preincubation with 10(-7) M GIP. In betaTC3 cells, preincubation of GIP attenuated GIP-induced insulin release by 45% at 15 min and by 55% at 30 min. Expression of RGS2 in the betaTC3 cells significantly decreased GIP-stimulated insulin secretion, whereas glucose-induced insulin release was not affected. RGS2 messenger RNA was identified by Northern blot analysis to be expressed endogenously in betaTC3 and L293 cells, and its level was significantly induced by GIP treatment in betaTC3 cells. Moreover, RGS2 bound Gs alpha protein in an in vitro system, suggesting that RGS2 attenuated the Gs-adenylate cyclase signaling pathway. These results suggest a potential role for RGS2 in modulating GIP-mediated insulin secretion in pancreatic islet cells.

    Funded by: NIDDK NIH HHS: DK-52186

    Endocrinology 1998;139;11;4470-5

  • GNAS1 mutational analysis in pseudohypoparathyroidism.

    Ahmed SF, Dixon PH, Bonthron DT, Stirling HF, Barr DG, Kelnar CJ and Thakker RV

    MRC Molecular Endocrinology Group, Imperial College School of Medicine, Hammersmith Hospital London, UK.

    Objective: Mutations of the GNAS1 gene, which is located on chromosome 20q13.11 and encodes the alpha-subunit of the stimulatory GTP-binding protein, have been identified in patients with pseudohypoparathyroidism type Ia (PHPIa) and pseudopseudohypoparathyroidism (PPHP). We have undertaken studies to determine the prevalence of GNAS1 mutations and to explore methods for their more rapid detection.

    Methods: Thirteen unrelated families (8 with PHPIa and PPHP patients, and 5 with PPHP patients only) were investigated for GNAS1 mutations in the 1050 base-pair (bp) region spanning exons 2-13 by single-stranded conformational polymorphism (SSCP) and DNA sequence analysis.

    Results: GNAS1 mutations were detected in 4 of the 8 families with PHPIa patients. These consisted of: two novel de novo missense mutations (Pro115Ser and Glu259Val) in two families and an identical 4 bp deletion of codons 189 and 190 resulting in a frame-shift in two unrelated families. These results expand the spectrum of GNAS1 mutations associated with this disorder and confirm the presence of a mutational hot-spot involving codons 189 and 190. SSCP analysis was found to be a specific and sensitive method that detected all 4 mutations. GNAS1 mutations were not detected in any of the PPHP only families.

    Conclusions: The pseudohypoparathyroid disorders appear to represent a heterogeneous group with GNAS1 mutations forming the molecular aetiology in approximately 50% of pseudohypoparathyroidism type Ia families. Such mutations can be reliably identified by single-stranded conformational polymorphism and this will help to supplement the clinical evaluation of some patients and their families, particularly as the disease may not be fully penetrant.

    Clinical endocrinology 1998;49;4;525-31

  • A novel mutation in the switch 3 region of Gsalpha in a patient with Albright hereditary osteodystrophy impairs GDP binding and receptor activation.

    Warner DR, Weng G, Yu S, Matalon R and Weinstein LS

    Membrane Biochemistry Section, Laboratory of Molecular and Cellular Neurobiology, NINDS, National Institutes of Health, Bethesda, Maryland 20892, USA. dwarner@helix.nih.gov

    Albright hereditary osteodystrophy (AHO), a disorder 17e8 characterized by skeletal abnormalities and obesity, is associated with heterozygous inactivating mutations in the gene for Gsalpha. A novel Gsalpha mutation encoding the substitution of tryptophan for a nonconserved arginine within the switch 3 region (Gsalpha R258W) was identified in an AHO patient. Although reverse transcription-polymerase chain reaction studies demonstrated that mRNA expression from wild type and mutant alleles was similar, Gsalpha expression in erythrocyte membranes from the affected patient was reduced by 50%. A Gsalpha R258W cDNA, as well as one with arginine replaced by alanine (Gsalpha R258A), was generated, and the biochemical properties of in vitro transcription/translation products were examined. When reconstituted with cyc- membranes, both mutant proteins were able to stimulate adenylyl cyclase normally in the presence of guanosine- 5'-O-(3-thiotriphosphate) (GTPgammaS) but had decreased ability in the presence of isoproterenol or AlF4- (a mixture of 10 microM AlCl3 and 10 mM NaF). The ability of each mutant to bind and be activated by GTPgammaS or AlF4- was assessed by trypsin protection assays. Both mutants were protected normally by GTPgammaS but showed reduced protection in the presence of AlF4-. The addition of excess GDP (2 mM) was able to rescue the ability of AlF4- to protect the mutants, suggesting that they might have reduced affinity for GDP. A Gsalpha R258A mutant purified from Escherichia coli had decreased affinity for GDP and an apparent rate of GDP release that was 10-fold greater than that of wild type Gsalpha. Sucrose density gradient analysis demonstrated that both Gsalpha R258W and Gsalpha R258A were thermolabile at higher temperatures and that denaturation of both mutants was prevented by the presence of 0.1 mM GTPgammaS or 2 mM GDP. The crystal structure of Gsalpha demonstrates that Arg258 interacts with a conserved residue in the helical domain (Gln170). Arg258 substitutions would be predicted to open the cleft between the GTPase and helical domains, allowing for increased GDP release in the inactive state, resulting in enhanced thermolability and reduced AlF4--induced adenylyl cyclase stimulation and trypsin protection, since activation by AlF4- requires bound GDP.

    The Journal of biological chemistry 1998;273;37;23976-83

  • The human GNAS1 gene is imprinted and encodes distinct paternally and biallelically expressed G proteins.

    Hayward BE, Kamiya M, Strain L, Moran V, Campbell R, Hayashizaki Y and Bonthron DT

    Human Genetics Unit, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom.

    The GNAS1 gene encodes the alpha subunit of the G protein Gs, which couples receptor binding by several hormones to activation of adenylate cyclase. Null mutations of GNAS1 cause pseudohypoparathyroidism (PHP) type Ia, in which hormone resistance occurs in association with a characteristic osteodystrophy. The observation that PHP Ia almost always is inherited maternally has led to the suggestion that GNAS1 may be an imprinted gene. Here, we show that, although Gsalpha expression (directed by the promoter upstream of exon 1) is biallelic, GNAS1 is indeed imprinted in a promoter-specific fashion. We used parthenogenetic lymphocyte DNA to screen by restriction landmark genomic scanning for loci showing differential methylation between paternal and maternal alleles. This screen identified a region that was found to be methylated exclusively on a maternal allele and was located approximately 35 kb upstream of GNAS1 exon 1. This region contains three novel exons that are spliced into alternative GNAS1 mRNA species, including one exon that encodes the human homologue of the large G protein XLalphas. Transcription of these novel mRNAs is exclusively from the paternal allele in all tissues examined. The differential imprinting of separate protein products of GNAS1 therefore may contribute to the anomalous inheritance of PHP Ia.

    Funded by: Wellcome Trust

    Proceedings of the National Academy of Sciences of the United States of America 1998;95;17;10038-43

  • The mammalian calcium-binding protein, nucleobindin (CALNUC), is a Golgi resident protein.

    Lin P, Le-Niculescu H, Hofmeister R, McCaffery JM, Jin M, Hennemann H, McQuistan T, De Vries L and Farquhar MG

    Division of Cellular and Molecular Medicine and Department of Pathology, University of California, San Diego, La Jolla, California 92093-0651, USA.

    We have identified CALNUC, an EF-hand, Ca2+-binding protein, as a Golgi resident protein. CALNUC corresponds to a previously identified EF-hand/calcium-binding protein known as nucleobindin. CALNUC interacts with Galphai3 subunits in the yeast two-hybrid system and in GST-CALNUC pull-down assays. Analysis of deletion mutants demonstrated that the EF-hand and intervening acidic regions are the site of CALNUC's interaction with Galphai3. CALNUC is found in both cytosolic and membrane fractions. The membrane pool is tightly associated with the luminal surface of Golgi membranes. CALNUC is widely expressed, as it is detected by immunofluorescence in the Golgi region of all tissues and cell lines examined. By immunoelectron microscopy, CALNUC is localized to cis-Golgi cisternae and the cis-Golgi network (CGN). CALNUC is the major Ca2+-binding protein detected by 45Ca2+-binding assay on Golgi fractions. The properties of CALNUC and its high homology to calreticulin suggest that it may play a key role in calcium homeostasis in the CGN and cis-Golgi cisternae.

    Funded by: NCI NIH HHS: CA 58689; NIDDK NIH HHS: DK 17780, R01 DK017780

    The Journal of cell biology 1998;141;7;1515-27

  • Activating mutation of the stimulatory G protein (gsp) as a putative cause of ovarian and testicular human stromal Leydig cell tumors.

    Fragoso MC, Latronico AC, Carvalho FM, Zerbini MC, Marcondes JA, Araujo LM, Lando VS, Frazzatto ET, Mendonca BB and Villares SM

    Division of Endocrinology, Hospital das Clínicas, São Paulo University School of Medicine, Brazil.

    Activating mutations of the G protein genes have been associated with the development of several endocrine neoplasms. Such activating mutations, gip2, affecting the alpha-subunit of the G alpha i2 protein were previously described by a single group in 30% of ovarian sex cord stromal tumors. Other activating mutations of the alpha-subunit of the Gs (gsp) have been identified in GH-secreting and nonfunctioning pituitary tumors, autonomous thyroid adenomas, and all affected McCune-Albright tissues, but not in sex cord stromal tumors. In the present study, we investigated the presence of gip2 and gsp mutations in 14 human sex cord stromal tumors. Six Leydig cell tumors (4 ovaries and 2 testes), 2 thecomas, 2 granulosa cell tumors, 3 androblastomas, and 1 gonadoblastoma (sex cord and germ cell) were included in this study. Genomic DNA was obtained from either fresh-frozen tumor tissues or paraffin-embedded sections and in some cases from blood samples. Using PCR, denaturing gradient gel electrophoresis, and direct sequencing, we detected 4 tumors (66.6%) with the gsp mutation (R201C) in our series of ovarian and testicular Leydig cell tumors. In contrast, no gip2 mutations were found in any of the sex cord stromal tumors studied. In conclusion, our findings suggest that the putative oncogene gsp may play a significant role in the molecular mechanism of these tumors.

    The Journal of clinical endocrinology and metabolism 1998;83;6;2074-8

  • Deletions in the third intracellular loop of the thyrotropin receptor. A new mechanism for constitutive activation.

    Wonerow P, Schöneberg T, Schultz G, Gudermann T and Paschke R

    Medizinische Klinik und Poliklinik III, Universität Leipzig, 04103 Leipzig, Germany.

    Gain-of-function mutations of the thyrotropin receptor (TSHR) gene have been invoked as one of the major causes of toxic thyroid adenomas. In a toxic thyroid nodule, we recently identified a 9-amino acid deletion (amino acid positions 613-621) within the third intracellular (i3) loop of the TSHR resulting in constitutive receptor activity. This finding exemplifies a new mechanism of TSHR activation and raises new questions concerning the function of the i3 loop. Because the i3 loop is thought to be critical for receptor/G protein interaction in many receptors, we systematically reexamined the role of the TSHR's i3 loop for G protein coupling. Thus, various deletion mutants were generated and functionally characterized. We identified an optimal deletion length responsible for constitutive activity. If the number of deleted amino acids was reduced, elevated basal cAMP accumulation was found to be concomitantly diminished. Expansion of the deletion dramatically impaired cell surface expression of the receptor. Shifting the deletion toward the N terminus of the i3 loop resulted in unaltered strong constitutive receptor activity. In contrast, translocation of the deletion toward the C terminus led to significantly reduced basal cAMP formation, most probably due to destruction of a conserved cluster of amino acids. In this study, we show for the first time that amino acid deletions within the i3 loop of a G protein-coupled receptor result in constitutive receptor activity. In the TSHR, 75% of the i3 loop generally assumed to play an essential role in G protein coupling can be deleted without rendering the mutant receptor unresponsive to thyrotropin. These findings support a novel model explaining the molecular events accompanying receptor activation by agonist.

    The Journal of biological chemistry 1998;273;14;7900-5

  • An inherited mutation associated with functional deficiency of the alpha-subunit of the guanine nucleotide-binding protein Gs in pseudo- and pseudopseudohypoparathyroidism.

    Fischer JA, Egert F, Werder E and Born W

    Department of Orthopedic Surgery, University of Zurich, Switzerland.

    Pseudohypoparathyroidism type Ia (PSP) is a disorder characterized by Albright's osteodystrophy, secondary hyperparathyroidism, lowered Gs activity, and resistance of the urinary cAMP excretion to exogenous PTH. The patients had raised basal serum levels of TSH and/or excessive TSH response to TRH. Here we have described a 38-bp deletion at the exon 1/intron 1 boundary of one Gs alpha allele in two mothers with pseudo-PSP and in six offsprings with PSP of a kindred with Albright's osteodystrophy. The deletion eliminates the splice donor site of exon 1. The pseudo-PSP patients presented decreased Gs activity, but normal urinary cAMP responses to PTH and normal TSH levels and responses to TRH. As monitored during 22 yr, they had normal serum levels of calcium and PTH. The findings demonstrate the same inherited functional defect of Gs alpha in two female patients with pseudo-PSP and in six of their offspring with PSP. The pathogenesis of clinical hypoparathyroidism remains to be clarified.

    The Journal of clinical endocrinology and metabolism 1998;83;3;935-8

  • Crystal structure of the catalytic domains of adenylyl cyclase in a complex with Gsalpha.GTPgammaS.

    Tesmer JJ, Sunahara RK, Gilman AG and Sprang SR

    Howard Hughes Medical Institute and Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75235-9050, USA.

    The crystal structure of a soluble, catalytically active form of adenylyl cyclase in a complex with its stimulatory heterotrimeric G protein alpha subunit (Gsalpha) and forskolin was determined to a resolution of 2.3 angstroms. When P-site inhibitors were soaked into native crystals of the complex, the active site of adenylyl cyclase was located and structural elements important for substrate recognition and catalysis were identified. On the basis of these and other structures, a molecular mechanism is proposed for the activation of adenylyl cyclase by Gsalpha.

    Funded by: NIDDK NIH HHS: DK38828, DK46371; NIGMS NIH HHS: GM34497

    Science (New York, N.Y.) 1997;278;5345;1907-16

  • Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library.

    Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, Suyama A and Sugano S

    International and Interdisciplinary Studies, The University of Tokyo, Japan.

    Using 'oligo-capped' mRNA [Maruyama, K., Sugano, S., 1994. Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides. Gene 138, 171-174], whose cap structure was replaced by a synthetic oligonucleotide, we constructed two types of cDNA library. One is a 'full length-enriched cDNA library' which has a high content of full-length cDNA clones and the other is a '5'-end-enriched cDNA library', which has a high content of cDNA clones with their mRNA start sites. The 5'-end-enriched library was constructed especially for isolating the mRNA start sites of long mRNAs. In order to characterize these libraries, we performed one-pass sequencing of randomly selected cDNA clones from both libraries (84 clones for the full length-enriched cDNA library and 159 clones for the 5'-end-enriched cDNA library). The cDNA clones of the polypeptide chain elongation factor 1 alpha were most frequently (nine clones) isolated, and more than 80% of them (eight clones) contained the mRNA start site of the gene. Furthermore, about 80% of the cDNA clones of both libraries whose sequence matched with known genes had the known 5' ends or sequences upstream of the known 5' ends (28 out of 35 for the full length-enriched library and 51 out of 62 for the 5'-end-enriched library). The longest full-length clone of the full length-enriched cDNA library was about 3300 bp (among 28 clones). In contrast, seven clones (out of the 51 clones with the mRNA start sites) from the 5'-end-enriched cDNA library came from mRNAs whose length is more than 3500 bp. These cDNA libraries may be useful for generating 5' ESTs with the information of the mRNA start sites that are now scarce in the EST database.

    Gene 1997;200;1-2;149-56

  • A novel mutation adjacent to the switch III domain of G(S alpha) in a patient with pseudohypoparathyroidism.

    Warner DR, Gejman PV, Collins RM and Weinstein LS

    Laboratory of Molecular and Cellular Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.

    A novel G(S alpha) mutation encoding the substitution of arginine for serine 250 (G[S alpha] S250R) was identified in a patient with pseudohypoparathyroidism type Ia. Both G(S) activity and G(S alpha) expression were decreased by about 50% in erythrocyte membranes from the affected patient. The cDNA of this G(S alpha) mutant, as well as one in which the S250 residue is deleted (G[S alpha]-deltaS250), was generated, and the biochemical properties of the products of in vitro transcription/translation were examined. Both mutants had a sedimentation coefficient similar to that of wild type G(S alpha) (approximately 3.7S) when kept at 0 C after synthesis. However when maintained for 1-2 h at 30-37 C, both mutants aggregated to a material sedimenting at approximately 6.3S or greater (G[S alpha]-S250R to a greater extent than G(S alpha]-deltaS250), while wild type G(S alpha) sedimented at approximately 3.7S, suggesting that the mutants were thermolabile. Incubation in the presence of high doses of guanine nucleotide partially prevented heat denaturation of G(S alpha) deltaS250 but had no protective effect on G(S alpha-S250R. Sucrose density gradient centrifugation at 0 C in the presence and absence of beta gamma-dimers demonstrated that, in contrast to wild type G(S alpha) neither mutant could interact with beta gamma. Trypsin protection assays revealed no protection of G(S alpha)-S250R by GTPgammaS or AIF4- at any temperature. GTPgammaS conferred modest protection of G(S alpha)-deltaS250 (approximately 50% of wild-type G[S alpha]) at 30 C but none at 37 C, while AIF4- conferred slight protection at 20 C but none at 30 C or above. Consistent with this result, G(S alpha)-deltaS250 was able to stimulate adenylyl cyclase at 30 C when reconstituted with cyc- membranes in the presence of GTPgammaS but not in the presence of AIF4-. G(S alpha)-S250R showed no ability to stimulate adenylyl cyclase in the presence of either agent. Stable transfection of mutant and wild-type G(S alpha) into cyc- S49 lymphoma cells revealed that the majority of wild type G(S alpha) localized to membranes, while little or no membrane localization occurred for either mutant. Modeling of G(S alpha) based upon the crystal structure of G(t alpha) or G(i alpha) suggests that Ser250 interacts with several residues within and around the conserved NKXD motif, which directly interacts with the guanine ring of bound GDP or GTP. It is therefore possible that substitution or deletion of this residue may alter guanine nucleotide binding, which could lead to thermolability and impaired function.

    Molecular endocrinology (Baltimore, Md.) 1997;11;11;1718-27

  • Interaction of Gsalpha with the cytosolic domains of mammalian adenylyl cyclase.

    Sunahara RK, Dessauer CW, Whisnant RE, Kleuss C and Gilman AG

    Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9041, USA.

    Forskolin- and Gsalpha-stimulated adenylyl cyclase activity is observed after mixture of two independently-synthesized approximately 25-kDa cytosolic fragments derived from mammalian adenylyl cyclases (native Mr approximately 120,000). The C1a domain from type V adenylyl cyclase (VC1) and the C2 domain from type II adenylyl cyclase (IIC2) can both be expressed in large quantities and purified to homogeneity. When mixed, their maximally stimulated specific activity, 150 micromol/min/mg protein, substantially exceeds values observed previously with the intact enzyme. A soluble, high-affinity complex containing one molecule each of VC1, IIC2, and guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS)-Gsalpha is responsible for the observed enzymatic activity and can be isolated. In addition, GTPgammaS-Gsalpha interacts with homodimers of IIC2 to form a heterodimeric complex (one molecule each of Gsalpha and IIC2) but not detectably with homodimers of VC1. Nevertheless, Gsalpha can be cross-linked to VC1 in the activated heterotrimeric complex of VC1, IIC2, and Gsalpha, indicating its proximity to both components of the enzyme that are required for efficient catalysis. These results and those in the accompanying report (Dessauer, C. W., Scully, T. T., and Gilman, A. G. (1997) J. Biol. Chem. 272, 22272-22277) suggest that activators of adenylyl cyclase facilitate formation of a single, high-activity catalytic site at the interface between C1 and C2.

    Funded by: NIGMS NIH HHS: GM16905, GM34497

    The Journal of biological chemistry 1997;272;35;22265-71

  • Polymerase chain reaction-based technique for the selective enrichment and analysis of mosaic arg201 mutations in G alpha s from patients with fibrous dysplasia of bone.

    Candeliere GA, Roughley PJ and Glorieux FH

    Genetics Unit, Shriners Hospital for Children, Montreal, Quebec, Canada.

    Mutations in the arg201 codon of the alpha s G protein-subunit have been associated with a variety of disorders, but analysis of such mutations has been complicated by their mosaic presentation. To overcome the problems associated with the analysis of genomic mutations that may be present in low and variable yield throughout the body, a polymerase chain reaction (PCR)-based technique has been developed that allows the selective amplification of products from the mutant allele. This technique uses site-directed mutagenesis to generate a PCR product from the normal allele that is susceptible to restriction endonuclease digestion, whereas that from the mutant allele is resistant to digestion. Consecutive and repeated cycles of amplification and digestion allow selective enrichment of the product from the mutant allele. The technique has been applied to the analysis of patients with fibrous dysplasia of bone, where the consequence of G alpha s mutations may vary from monostotic to polyostotic lesions, and has been performed with DNA isolated from either bone biopsy specimens or peripheral blood leukocytes. In addition to the previously described arg-->his and arg-->cys substitutions, the analyses have detected a novel arg-->ser substitution in one of the patients. This patient presented with a panostotic disease and may represent a unique subgroup of fibrous dysplasia.

    Bone 1997;21;2;201-6

  • Differential regulation of adenylyl cyclases by Galphas.

    Harry A, Chen Y, Magnusson R, Iyengar R and Weng G

    Department of Pharmacology, Mount Sinai School of Medicine, New York, New York 10029, USA.

    Regulation of adenylyl cyclases 1, 2, and 6 by Galphas was studied. All three mammalian adenylyl cyclases were expressed in insect (Sf9 or Hi-5) cells by baculovirus infection. Membranes containing the different adenylyl cyclases were stimulated by varying concentrations of mutant (Q227L) activated Galphas expressed in reticulocyte lysates. Galphas stimulation of AC1 involved a single site and had an apparent Kact of 0.9 nM. Galphas stimulation of AC2 was best explained by a non-interactive two site model with a "high affinity" site at 0.9 nM and a "low affinity" site at 15 nM. Occupancy of the high affinity site appears to be sufficient for Gbetagamma stimulation of AC2. Galphas stimulation of AC6 was also best explained by a two-site model with a high affinity site at 0. 6-0.8 nM and a low affinity site at 8-22 nM; however, in contrast to AC2, only a model that assumed interactions between the two sites best fit the AC6 data. With 100 microM forskolin, Galphas stimulation of all three adenylyl cyclases showed very similar profiles. Galphas stimulation in the presence of forskolin involved a single site with apparent Kact of 0.1-0.4 nM. These observations indicate a conserved mechanism by which forskolin regulates Galphas coupling to the different adenylyl cyclases. However, there are fundamental differences in the mechanism of Galphas stimulation of the different adenylyl cyclases with AC2 and AC6 having multiple interconvertible sites. These mechanistic differences may provide an explanation for the varied responses by different cells and tissues to hormones that elevate cAMP levels.

    Funded by: NIDDK NIH HHS: DK-38761; NIGMS NIH HHS: GM15599, GM54508; ...

    The Journal of biological chemistry 1997;272;30;19017-21

  • Conditional activation defect of a human Gsalpha mutant.

    Iiri T, Farfel Z and Bourne HR

    Department of Cellular and Molecular Pharmacology, S-1212, Box 0450, University of California, San Francisco, CA 94143, USA.

    Hormonal signals activate trimeric G proteins by promoting exchange of GTP for GDP bound to the G protein's alpha subunit (Galpha). Here we describe a point mutation that impairs this activation mechanism in the alpha subunit of Gs, producing an inherited disorder of hormone responsiveness. Biochemical analysis reveals an activation defect that is paradoxically intensified by hormonal and other stimuli. By substituting histidine for a conserved arginine residue, the mutation removes an internal salt bridge (to a conserved glutamate) that normally acts as an intramolecular hasp to maintain tight binding of the gamma-phosphate of GTP. In its basal, unperturbed state, the mutant alphas binds guanosine 5'-[gamma-thio]triphosphate (GTP[gammaS]), a GTP analog, slightly less tightly than does normal alphas, but (in the GTP[gammaS]-bound form) can stimulate adenylyl cyclase. The activation defect becomes prominent only under conditions that destabilize binding of guanine nucleotide (receptor stimulation) or impair the ability of alphas to bind the gamma-phosphate of GTP (cholera toxin, AlF4- ion). Although GDP release is usually the rate-limiting step in nucleotide exchange, the biochemical phenotype of this mutant alphas indicates that efficient G protein activation by receptors and other stimuli depends on the ability of Galpha to clasp tightly the GTP molecule that enters the binding site.

    Funded by: NIGMS NIH HHS: GM27800, R01 GM027800, R37 GM027800

    Proceedings of the National Academy of Sciences of the United States of America 1997;94;11;5656-61

  • Pseudohypoparathyroidism, a novel mutation in the betagamma-contact region of Gsalpha impairs receptor stimulation.

    Farfel Z, Iiri T, Shapira H, Roitman A, Mouallem M and Bourne HR

    Laboratory of Biochemical Pharmacology, Sheba Medical Center, Tel Aviv University, Tel Hashomer 52621, Israel.

    Pseudohypoparathyroidism, type Ia (PHP-Ia), is a dominantly inherited endocrine disorder characterized by resistance to hormones that act by stimulating adenylyl cyclase. It is caused by inheritance of an autosomal mutation that inactivates the alpha subunit (alphas) of Gs, the stimulatory regulator of adenylyl cyclase. In three members of a family, the PHP-Ia phenotype is associated with a mutation (R231H) that substitutes histidine for an arginine at position 231 in alphas. We assessed signaling function of alphas-WT versus alphas-R231H transiently transfected in HEK293 cells. Hormone receptor-dependent stimulation of cAMP accumulation in cells expressing alphas-R231H is reduced by approximately 75% in comparison to cAMP accumulation in cells expressing alphas-WT. A second mutation, alphas-R201C, inhibits the GTPase turnoff reaction of alphas, thus producing receptor-independent stimulation of cAMP accumulation. The double mutant, alphas-R231H/R201C, stimulates cAMP accumulation almost as well (approximately 80%) as does alphas-R201C itself, indicating that the R231H mutation selectively impairs receptor-dependent signaling. In three-dimensional structures of G protein heterotrimers, Arg-231 is located in a region, switch 2, that is thought to interact with the betagamma subunit rather than with the hormone receptor. Thus, the R231H phenotype suggests that switch 2 (perhaps in concert with betagamma) mediates G protein activation by receptors at a site distant from the receptor-G protein contact surface.

    The Journal of biological chemistry 1996;271;33;19653-5

  • Involvement of Gs and Gi proteins in dual coupling of the luteinizing hormone receptor to adenylyl cyclase and phospholipase C.

    Herrlich A, Kühn B, Grosse R, Schmid A, Schultz G and Gudermann T

    Institut für Pharmakologie, Freie Universität Berlin, Thielallee 69-73, D-14195 Berlin, Germany.

    Binding of lutropin/choriogonadotropin to its cognate receptor results in the activation of adenylyl cyclase and phospholipase C. The mechanism underlying the generation of this bifurcating signal is presently not known. To analyze the coupling mechanism of the LH receptor, activated G proteins were labeled with [alpha-32P]GTP azidoanilide and identified by selective immunoprecipitation. In membranes of bovine corpora lutea and of L cells stably expressing the murine LH receptor (LHR cells), human chorionic gonadotropin (hCG) led to incorporation of the label into alphas and alphai2. Stimulation of LHR cells or of L cells expressing the M5 muscarinic receptor (LM5 cells) with the respective agonist resulted in activation of phospholipase C in both cell lines. However, alphaq and alpha11 were only labeled upon stimulation of the M5 muscarinic receptor. Agonist-induced Ca2+ mobilization and inositol phosphate accumulation were partially sensitive to pertussis toxin, and the expression of the betagamma-stimulable phospholipase C isoforms beta2 and beta3 could be demonstrated in LHR cells. Overexpression of phospholipase C-beta2 led to increased hCG-stimulated inositol phosphate accumulation, and expression of a beta-ARK1 C-terminal polypeptide effectively suppressed hCG-mediated phosphatidylinositol hydrolysis. Thus, the LH receptor couples to both Gs and Gi, and betagamma-subunits released from either G protein contribute to the stimulation of phospholipase C-beta isoforms.

    The Journal of biological chemistry 1996;271;28;16764-72

  • Characteristics of gsp-positive growth hormone-secreting pituitary tumors in Korean acromegalic patients.

    Yang I, Park S, Ryu M, Woo J, Kim S, Kim J, Kim Y and Choi Y

    Department of Internal Medicine, Kyunghee University School of Medicine, Seoul, Korea.

    A subset of human growth hormone (GH)-secreting pituitary tumors contains the gsp oncogene that encodes an activation mutation of the alpha-subunit of the stimulatory GTP-binding protein (G(S) alpha). This study was undertaken to in 1c78 vestigate the frequency of the gsp oncogene in GH-secreting pituitary tumors in Korean acromegalic patients and to elucidate the clinical characteristics of these patients to endocrine testing. Direct polymerase chain reaction sequencing revealed the gsp oncogene mutation in 9 out of 21 tumors (43%) at amino acid 201 of the G(S) alpha protein. A single nucleotide mutation in the tumors carrying the gsp oncogene was observed, which replaced an arginine (CGT) in the normal protein with cysteine (TGT) in eight tumors and serine (AGT) in one tumor. The patients with the gsp oncogene mutation (group 1) were older (54 +/- 10 vs 41 +/- 11 years, p = 0.0085) than those without the mutation (group 2). Sex, tumor size and grade, basal GH and prolactin levels, the GH response to oral glucose loading, the GH fluctuation and the paradoxical response to thyrotropin-releasing hormone or gonadotropin-releasing hormone did not differ between the groups. The gsp oncogene was found mostly in somatotroph adenomas. The octreotide-induced GH suppression was significantly higher in group 1 than in group 2 (95 +/- 5% vs 81 +/- 17%, p = 0.0335). The GH response to bromocriptine did not differ between the groups. These results suggest that the G(S) alpha mutations of GH-secreting tumor are observed in Korean acromegalic patients with similar frequency to those of western countries. The patients with gsp oncogene are likely to be older than those without the oncogene, and show excellent response of GH suppression to octreotide.

    European journal of endocrinology 1996;134;6;720-6

  • Different single receptor domains determine the distinct G protein coupling profiles of members of the vasopressin receptor family.

    Liu J and Wess J

    Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.

    The vasopressin receptor family is unique among all classes of peptide receptors in that its individual members couple to different subsets of G proteins. The V1a vasopressin receptor, for example, is preferentially linked to G proteins of the Gq/11 class (biochemical response: stimulation of phosphatidylinositol hydrolysis), whereas the V2 vasopressin receptor is selectively coupled to Gs (biochemical response: stimulation of adenylyl cyclase). To elucidate the structural basis underlying this functional heterogeneity, we have systematically exchanged different intracellular domains between the V1a and V2 receptors. Transient expression of the resulting hybrid receptors in COS-7 cells showed that all mutant receptors containing V1a receptor sequence in the second intracellular loop were able to activate the phosphatidylinositol pathway with high efficiency. On the other hand, only those hybrid receptors containing V2 receptor sequence in the third intracellular loop were capable of efficiently stimulating cAMP production. These findings suggest that the differential G protein coupling profiles of individual members of a structurally closely related receptor subfamily can be determined by different single intracellular receptor domains.

    The Journal of biological chemistry 1996;271;15;8772-8

  • The human thyrotropin receptor: a heptahelical receptor capable of stimulating members of all four G protein families.

    Laugwitz KL, Allgeier A, Offermanns S, Spicher K, Van Sande J, Dumont JE and Schultz G

    Institut für Pharmakologie, Freie Universität Berlin, Germany.

    Thyrotropin is the primary hormone that, via one heptahelical receptor, regulates thyroid cell functions such as secretion, specific gene expression, and growth. In human thyroid, thyrotropin receptor activation leads to stimulation of the adenylyl cyclase and phospholipase C cascades. However, the G proteins involved in thyrotropin receptor action have been only partially defined. In membranes of human thyroid gland, we immunologically identified alpha subunits of the G proteins Gs short, Gs long, Gi1, Gi2, Gi3, G(o) (Go2 and another form of Go, presumably Go1), Gq, G11, G12, and G13. Activation of the thyrotropin (TSH) receptor by bovine TSH led to increased incorporation of the photoreactive GTP analogue [alpha-32P]GTP azidoanilide into immunoprecipitated alpha subunits of all G proteins detected in thyroid membranes. This effect was receptor-dependent and not due to direct G protein stimulation because it was mimicked by TSH receptor-stimulating antibodies of patients suffering from Grave disease and was abolished by a receptor-blocking antiserum from a patient with autoimmune hypothyroidism. The TSH-induced activation of individual G proteins occurred with EC50 values of 5-50 milliunits/ml, indicating that the activated TSH receptor coupled with similar potency to different G proteins. When human thyroid slices were pretreated with pertussis toxin, the TSH receptor-mediated accumulation of cAMP increased by approximately 35% with TSH at 1 milliunits/ml, indicating that the TSH receptor coupled to Gs and G(i). Taken together, these findings show that, at least in human thyroid membranes, in which the protein is expressed at its physiological levels, the TSH receptor resembles a naturally occurring example of a general G protein-activating receptor.

    Proceedings of the National Academy of Sciences of the United States of America 1996;93;1;116-20

  • Osteoblastic cells derived from isolated lesions of fibrous dysplasia contain activating somatic mutations of the Gs alpha gene.

    Shenker A, Chanson P, Weinstein LS, Chi P, Spiegel AM, Lomri A and Marie PJ

    Metabolic Diseases Branch, National Institute of Diabetes and Digestive and K 1f40 idney Diseases, National Institutes of Health, Bethesda, MD 20892-1752, USA.

    Human molecular genetics 1995;4;9;1675-6

  • Evidence for a regulated interaction between heterotrimeric G proteins and caveolin.

    Li S, Okamoto T, Chun M, Sargiacomo M, Casanova JE, Hansen SH, Nishimoto I and Lisanti MP

    Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142-1479, USA.

    Caveolae are flask-shaped plasma membrane specializations. A 22-kDa protein, caveolin, is a principal component of caveolar membranes in vivo. As recent evidence suggests that caveolae may participate in G protein-coupled signaling events, we have investigated the potential interaction of caveolin with heterotrimeric G proteins. Using cell fractionation techniques, we found that mutational or pharmacologic activation of Gs alpha prevents its cofractionation with caveolin. In a second independent approach, we directly examined the interaction of G proteins with caveolin. For this purpose, we recombinantly expressed caveolin as a glutathione S-transferase fusion protein. Using an in vitro binding assay, we found that caveolin interacts with G protein alpha subunits (Gs, Go, and Gi). Mutational or pharmacologic activation (with guanosine 5'-O-(thiotriphosphate)) of G alpha subunits prevents this interaction, indicating that the inactive GDP-bound form of G alpha subunits preferentially interacts with caveolin. This G protein binding activity is located within a 41-amino acid region of caveolin's cytoplasmic N-terminal domain (residues 61-101). Further functional analysis shows that a polypeptide derived from this region of caveolin (residues 82-101) effectively suppresses the basal activity of purified G proteins, apparently by inhibiting GDP/GTP exchange. This caveolin sequence is homologous to a region of the Rab GDP dissociation inhibitor, a known inhibitor of GDP/GTP exchange for Rab proteins. These data suggest that caveolin could function to negatively regulate the activation state of heterotrimeric G proteins.

    Funded by: NIAID NIH HHS: AI-32991; NIGMS NIH HHS: GM-50443

    The Journal of biological chemistry 1995;270;26;15693-701

  • Increased expression of the c-fos proto-oncogene in bone from patients with fibrous dysplasia.

    Candeliere GA, Glorieux FH, Prud'homme J and St-Arnaud R

    Genetics Unit, Shriners Hospital, Montreal, QC, Canada.

    Background: Fibrous dysplasia is characterized by intense marrow fibrosis and increased rates of bone turnover. The lesions of fibrous dysplasia resemble those described in the long bones of transgenic mice overexpressing the c-fos proto-oncogene. Activating mutations in the alpha subunit of the stimulatory guanine-nucleotide-binding protein (GS alpha) linked to adenylate cyclase have recently been described in bone cells from patients with the McCune-Albright syndrome and fibrous dysplasia.

    Methods: We used in situ hybridization to determine the level of expression of c-fos in bone-biopsy specimens from two normal subjects, eight patients with fibrous dysplasia, and six patients with other bone disorders characterized by high rates of bone turnover. The probe used corresponded to the fourth exon of the c-fos gene.

    Results: High levels of c-fos expression were detected in the bone lesions from all eight patients with fibrous dysplasia. No expression of c-fos was detected in bone specimens from the normal subjects or from specimens of normal bone obtained from patients with fibrous dysplasia. The cells that expressed c-fos in the dysplastic lesions were fibroblastic and populated the marrow space. A very low level of c-fos expression was detected in the biopsy specimens from the patients with other bone diseases. One patient with polyostotic fibrous dysplasia and one patient with the McCune-Albright syndrome were tested for the previously described GS alpha gene mutations and were found to express these mutations in bone.

    Conclusions: Increased expression of the c-fos proto-oncogene, presumably a consequence of increased adenylate cyclase activity, may be important in the pathogenesis of the bone lesions in patients with fibrous dysplasia.

    The New England journal of medicine 1995;332;23;1546-51

  • G-protein mutations in human pituitary adrenocorticotrophic hormone-secreting adenomas.

    Williamson EA, Ince PG, Harrison D, Kendall-Taylor P and Harris PE

    Department of Medicine, Medical School, Newcastle upon Tyne, UK.

    Activating mutations of Gs alpha (gsp) and Gi2 alpha (gip) have been described in various endocrine neoplastic conditions. The objective of this study was to assess the prevalence of gsp and gip mutations in human adrenocorticotrophin hormone-secreting pituitary adenomas. Adrenocorticotrophin hormone production and secretion by pituitary corticotroph cells is under stimulatory control by corticotrophin-releasing factor, acting via the production of cyclic AMP. Interference with this regulatory pathway as a result of G-protein dysfunction could lead to disordered corticotroph cell function and growth. We have studied 32 corticotroph adenomas for the presence of gsp and gip mutations using site-directed oligonucleotide hybridization of polymerase chain reaction-amplified DNA. G-protein gene mutations were identified in three (9%) tumours: gsp mutations were demonstrated in two tumours at codon 227, and a gip mutation was identified in one 10f8 tumour at codon 179. We did not observe a correlation between tumour phenotype and the presence of G-protein gene mutations. We conclude that G-protein gene mutations are an uncommon abnormality in corticotroph adenomas.

    European journal of clinical investigation 1995;25;2;128-31

  • Overexpression of Gs alpha subunit in thyroid tumors bearing a mutated Gs alpha gene.

    Gorelov VN, Dumon K, Barteneva NS, Palm D, Röher HD and Goretzki PE

    Department of Surgery A, Heinrich-Heine-University, Düsseldorf, Germany.

    Point mutations occurring at codon 201 of the gene coding for the alpha subunit of the stimulatory G protein impair intrinsic GTPase activity and lead to a constitutive activation of adenylate cyclase. We have examined thyroid follicular and papillary carcinomas and follicular adenomas and found samples that bear this mutation at codon 201 of the Gs alpha gene. Both mutation-positive and mutation-negative tissue samples were investigated for the level of Gs alpha expression relative to a pool of normal thyroid tissue, using immunoblotting against two (mid-region-specific and C-end-specific) antipeptide antibodies. Using 8000 g and 100,000 g membrane fractions of homogenized tissues we have demonstrated that the Gs alpha proteins in normal ad neoplastic thyroid tissues are represented by three isoforms: 43 kDa, 45 kDa and 52 kDa. We have quantified and compared the amount of Gs alpha protein and find it is overexpressed in mutation-bearing tissue samples.

    Journal of cancer research and clinical oncology 1995;121;4;219-24

  • XL alpha s is a new type of G protein.

    Kehlenbach RH, Matthey J and Huttner WB

    Institute for Neurobiology, University of Heidelberg, Germany.

    The GTP-binding proteins are well-known regulators of cellular functions, including vesicular transport. Cholera toxin, which is known to catalyse ADP-ribosylation of the alpha s subunit of heterotrimeric G proteins, stimulates secretory vesicle formation from the trans-Golgi network. Here we describe a new cholera toxin target, an 'extra large' G protein (XL alpha s; M(r) 92K) which consists of a new 51K XL-portion linked to a G alpha s truncated at the amino terminus. XL alpha s is specifically associated with the trans-Golgi network and occurs selectively in cells containing both the regulated and the constitutive pathway of protein secretion. Hence, XL alpha s may mediate the effects of cholera toxin on secretory vesicle formation.

    Nature 1994;372;6508;804-9

  • A novel Gs alpha mutant in a patient with Albright hereditary osteodystrophy uncouples cell surface receptors from adenylyl cyclase.

    Schwindinger WF, Miric A, Zimmerman D and Levine MA

    Division of Endocrinology and Metabolism, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.

    Albright hereditary osteodystrophy (AHO) is an autosomal-dominant disorder characterized by decreased expression of Gs alpha and widespread tissue resistance to hormones that activate adenylyl cyclase. We identified a single mutation, R385H, in the Gs alpha gene of a subject with AHO who had evidence for a dysfunctional Gs alpha protein. The R385H substitution is near the carboxyl terminus of the Gs alpha protein and is located five amino acids upstream of the R389P mutation that uncouples Gs alpha from cell surface receptors in the unc clone of S49 murine lymphoma. To test the biological activity of the R385H mutant, we transiently expressed wild type, R385H, and R389P Gs alpha cDNAs in COS-1 cells. Neither of the mutant Gs alpha proteins stimulated adenylyl cyclase in response to l-isoproterenol (1 to 30 microM). By contrast, both mutant Gs alpha proteins showed activation of adenylyl cyclase in response to forskolin (10 microM) and fluoroaluminate (10 mM). We propose that the R385H mutation produces a Gs alpha molecule that is unable to interact with hormone receptors and results in uncoupling of adenylyl cyclase from cell surface receptors. This uncoupling mutation represents a new type of molecular defect that can result in AHO.

    Funded by: NCRR NIH HHS: RR0035; NIDDK NIH HHS: DK-08725, DK34281

    The Journal of biological chemistry 1994;269;41;25387-91

  • Rapid GDP release from Gs alpha in patients with gain and loss of endocrine function.

    Iiri T, Herzmark P, Nakamoto JM, van Dop C and Bourne HR

    Department of Pharmacology, University of California, San Francisco 94143-0450.

    Luteinizing hormone stimulates testicular Leydig cells to produce testosterone by binding to a receptor that activates the G protein Gs and adenylyl cyclase. Testotoxicosis is a form of precocious puberty in which the Leydig cells secrete testosterone in the absence of luteinizing hormone, often due to constitutive activation of the luteinizing hormone receptor and (indirectly) Gs (refs 1-4). Here we study two unrelated boys suffering from a paradoxical combination of testotoxicosis and pseudohypoparathyroidism type Ia (PHP-Ia), a condition marked by resistance to hormones acting through cyclic AMP (parathyroid hormone and thyroid-stimulating hormone) as well as a 50% decrease in erythrocyte Gs activity (the remaining 50% is due to the normal Gs allele). In both patients, a mutation in the gene encoding the Gs alpha-subunit replace alanine at position 366 with serine. We show that this alpha s-A366S mutation constitutively activates adenylyl cyclase in vitro, causing hormone-independent cAMP accumulation when expressed in cultured cells, and accounting for the testotoxicosis phenotype (as cAMP stimulates testosterone secretion). Although alpha s-A366S is quite stable at testis temperature, it is rapidly degraded at 37 degrees C explaining the PHP-Ia phenotype caused by loss of Gs activity. In vitro experiments indicate that accelerated release of GDP causes both the constitutive activity and the thermolability of alpha s-A366S.

    Nature 1994;371;6493;164-8

  • Parental origin of transcription from the human GNAS1 gene.

    Campbell R, Gosden CM and Bonthron DT

    Human Genetics Unit, University of Edinburgh, Western General Hospital, UK.

    Variation in the phenotypic expression of Albright's hereditary osteodystrophy (AHO) determined by the parent of transmission, suggests that the human Gs alpha gene (GNAS1), in which mutations occur in AHO, may be under imprinted control. GNAS1 is also known to map to a chromosomal region (20q13.11) showing syntenic homology with the imprinted mouse region 2E1-2H3. To establish if GNAS1 is indeed imprinted, we have examined the parental origin of GNAS1 transcription in human fetal tissues. Of 75 fetuses genotyped, at gestational ages ranging from 6 to 13 weeks, 13 heterozygous for a FokI polymorphism in exon 5 of GNAS1 were identified whose mothers were homozygous for one or other allele. RNA from up to 10 different tissues from each fetus was analysed by RT-PCR. In all cases expression from both parental alleles was shown by FokI digestion of RT-PCR products and quantification of the resulting fragments. No tissue specific pattern of expression was discerned in these experiments. If genomic imprinting regulates the expression of the human GNAS1 gene, our data suggest that the effect must either be subtle and quantitative, or be confined to a small subset of specialised hormone responsive cells within the target tissues.

    Journal of medical genetics 1994;31;8;607-14

  • Identification of cardiac autoantigens in human heart cDNA libraries using acute rheumatic fever sera.

    Eichbaum QG, Beatty DW and Parker MI

    Department of Medical Biochemistry, University of Cape Town Medical School, Observatory, South Africa.

    Antigenic mimicry or cross-reactivity between Group A streptococcal antigens and cardiac autoantigens may initiate an autoimmune response resulting in cardiovascular damage in acute rheumatic fever. This study describes a molecular biological approach to the identification of such cross-reactive cardiac antigens. Two human heart cDNA libraries were constructed in the expression vector lambda gt11 and screened with patient sera, monoclonal antibodies and rabbit immune sera cross-reactive with streptococcal and cardiac antigens. Using the serum of a patient with a recurrent acute attack of rheumatic fever containing high titres of antibodies cross-reactive with both sets of antigens, we were able to identify three positive clones with insert sizes of 1.0 kb, 1.4 kb and 0.9 kb in these libraries. Acute rheumatic fever (ARF) sera reacted more strongly with these autoantigen clones than did normal sera. Autoantibodies eluted from the purified plaques of all three clones displayed different patterns of cross-reactivity against immunoblots of streptococcal M5, M6, M19 and M24 protein extracts. The cDNA inserts were sequenced and compared with known sequences in the EMBL and Genbank databases. One clone was 98% homologous with human cytokeratin 8 and showed homologies of 40 to 50% with human cardiac heavy chain myosin, tropomyosin and streptococcal M5 protein--all members of the alpha-helical coiled-coil family of proteins. Another clone was completely homologous to the G-protein alpha-subunit of adenyl cyclase, whilst the sequence of the third clone was not found in any of the data banks.

    Journal of autoimmunity 1994;7;2;243-61

  • The complex of human Gs protein with the beta 3 adrenergic receptor: a computer-aided molecular modeling study.

    Mahmoudian M

    Department of Pharmacology, University of Medical Science, Tehran, Iran.

    Three-dimensional (3D) models of the human Gs protein, the human beta 3 adrenergic receptor and their complex are constructed using computer-aided molecular modeling techniques. The structures of bacterial EF-tu 200 and bacteriorhodopsin were used as starting points for modeling the Gs protein and beta 3 receptor, respectively. Experimental data are used as constraints to guide the modeling. The resulting 3D structures of the Gs protein, the beta 3 receptor and their complex are in accord with the experimental data. It is found that the third intracellular loop of the beta 3 receptor as well as its C-terminus are involved in the binding. Various residues of N-terminus and C-terminus of the Gs protein also participate in the binding. The model of the complex suggests that the Gs protein binds to the beta 3 receptor in such a way that it will be placed in the interface of membrane and intracellular space. This orientation is supported by experimental data. It is concluded that the modeled structure of the complex of the alpha subunit of the human Gs protein and the beta 3 adrenergic receptor is in agreement with the experimental data and it can provide a basis for understanding the way these proteins interact.

    Journal of molecular graphics 1994;12;1;22-8, 34

  • An unusual presentation of McCune-Albright syndrome confirmed by an activating mutation of the Gs alpha-subunit from a bone lesion.

    Malchoff CD, Reardon G, MacGillivray DC, Yamase H, Rogol AD and Malchoff DM

    Department of Surgery, University of Connecticut Health Center, Farmington 06030-1110.

    The McCune-Albright syndrome (MAS) is characterized clinically by polyostotic fibrous dysplasia, café-au-lait skin lesions, sexual precocity, and various other endocrinopathies. Recent investigations suggest an etiological role for embryonic somatic missense mutations that predict the substitution of a His or Cys for Arg fb1 at amino acid 201 of the Gs alpha-subunit (Gs alpha). Identification of these mutations in affected tissues is a sensitive assay that may help define a more complete clinical spectrum of the MAS. We investigated a woman who developed fibrous dysplasia 24 yr after premature menstruation. To determine if this was an unusual MAS variant, DNA and RNA were analyzed from affected and unaffected tissues. From samples of affected rib and normal rib DNA was extracted, amplified by polymerase chain reaction, subcloned, and sequenced. RNA was extracted from affected bone, reverse transcribed, amplified by polymerase chain reaction, subcloned, and sequenced. DNA sequence predicting a His for Arg substitution at Gs alpha amino acid 201 was found in 47% of the recombinant plasmids from DNA of affected bone and 17% of the plasmids from DNA of unaffected bone; a significant (P < 0.05) difference in frequency. The His201 substitution was found in 42% of the recombinant plasmids from RNA of affected bone. We conclude that this clinical variant is qualitatively indistinguishable from presentations of the complete MAS.

    The Journal of clinical endocrinology and metabolism 1994;78;3;803-6

  • Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides.

    Maruyama K and Sugano S

    Institute of Medical Science, University of Tokyo, Japan.

    We have devised a method to replace the cap structure of a mRNA with an oligoribonucleotide (r-oligo) to label the 5' end of eukaryotic mRNAs. The method consists of removing the cap with tobacco acid pyrophosphatase (TAP) and ligating r-oligos to decapped mRNAs with T4 RNA ligase. This reaction was made cap-specific by removing 5'-phosphates of non-capped RNAs with alkaline phosphatase prior to TAP treatment. Unlike the conventional methods that label the 5' end of cDNAs, this method specifically labels the capped end of the mRNAs with a synthetic r-oligo prior to first-strand cDNA synthesis. The 5' end of the mRNA was identified quite simply by reverse transcription-polymerase chain reaction (RT-PCR).

    Gene 1994;138;1-2;171-4

  • Heterogeneous mutations in the gene encoding the alpha-subunit of the stimulatory G protein of adenylyl cyclase in Albright hereditary osteodystrophy.

    Miric A, Vechio JD and Levine MA

    Department of Medicine, Johns Hopkins University School of Medicine, Balti 10b0 more, Maryland 21205.

    Albright hereditary osteodystrophy (AHO) is an inherited disorder associated with deficient activity of the alpha-subunit of the guanine nucleotide-binding regulatory protein (Gs alpha) that couples receptors to adenylyl cyclase. To identify mutations that lead to Gs alpha deficiency, we isolated genomic DNA from patients with AHO and used the polymerase chain reaction to amplify exons of the Gs alpha genes. DNA was amplified using intron-specific oligonucleotide primers flanking exons of the Gs alpha gene. To optimize our ability to detect mutations, one oligonucleotide from each primer pair was synthesized with a 5' GC-clamp. Amplified Gs alpha gene fragments were analyzed by denaturing gradient gel electrophoresis in order to detect mutations that alter the melting point of the double-stranded DNA fragment. Using this technique, we have identified and characterized three mutations and one neutral polymorphism. The polymorphism, located in exon 5, consisted of a T-->C substitution that conserves the isoleucine residue at codon 131 (ATT-->ATC). Two mutations were missense mutations, which in one family consisted of a nucleotide substitution (T-->C) in exon 4 that results in replacement of Leu by Pro at codon 99 of the Gs alpha molecule. Affected subjects in a second family had a single base (C-->T) mutation in exon 6 that resulted in replacement of Arg by Cys at codon 165. A 4-base pair deletion (GTGG) in exon 8 at position +214 was identified in one Gs alpha allele from each affected subject in the third family. This mutation causes a frameshift after the codon for Gln213 that results in a premature stop codon 81 base pair after the deletion. Immunoblot analysis of plasma membranes prepared from cultured fibroblasts or erythrocytes indicated that levels of immunoactive Gs alpha protein were decreased in all affected subjects. We conclude that heterogeneous mutations in the gene encoding Gs alpha, including deletions and single amino acid substitutions, are responsible for Gs alpha deficiency in AHO.

    Funded by: NCRR NIH HHS: GCRC 5M01RR00722; NIDDK NIH HHS: DK-34281

    The Journal of clinical endocrinology and metabolism 1993;76;6;1560-8

  • A heterozygous 4-bp deletion mutation in the Gs alpha gene (GNAS1) in a patient with Albright hereditary osteodystrophy.

    Weinstein LS, Gejman PV, de Mazancourt P, American N and Spiegel AM

    Molecular Pathophysiology Branch, National Institute of Diabetes, Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland 20892.

    Several heterozygous mutations within the gene encoding the alpha-subunit of Gs (GNAS1), the G protein that stimulates adenylyl cyclase, have been previously identified in patients with Albright hereditary osteodystrophy (AHO). We have now identified a fourth GNAS1 mutation from an AHO patient. Amplification by the polymerase chain reaction (PCR) of a genomic fragment encompassing GNAS1 exons 7 and 8 from one patient resulted in a product with aberrant migration on nondenaturing polyacrylamide and agarose gels. Direct DNA sequencing identified a 4-bp deletion in one allele of exon 7 encoding a frameshift with a premature stop codon. Analysis of lymphocyte RNA by reverse transcription-PCR and direct sequencing showed that the GNAS1 allele bearing the mutation is not expressed as mRNA. Consistent with this, Northern analysis revealed an approximate 50% deficiency in steady-state levels of GNAS1 mRNA. These findings further illustrate the heterogeneity of GNAS1 gene defects in AHO.

    Genomics 1992;13;4;1319-21

  • Identification of a mutation in the gene encoding the alpha subunit of the stimulatory G protein of adenylyl cyclase in McCune-Albright syndrome.

    Schwindinger WF, Francomano CA and Levine MA

    Division of Endocrinology and Metabolism, Johns Hopkins University School of Medicine, Baltimore, MD 21205.

    McCune-Albright syndrome (MAS) is characterized by polyostotic fibrous dysplasia, café-au-lait lesions, and a variety of endocrine disorders, including precocious puberty, hyperthyroidism, hypercortisolism, growth hormone excess, and hyperprolactinemia. The diverse metabolic abnormalities seen in MAS share the involvement of cells that respond to extracellular signals through activation of the hormone-sensitive adenylyl cyclase system (EC 4.6.1.1). Mutations that lead to constitutive activation of Gs alpha, the guanine nucleotide-binding regulatory protein that stimulates adenylyl cyclase activity, have been identified in a subset of human growth hormone-secreting pituitary tumors and human thyroid tumors. We report here the identification of a mutation in the gene encoding Gs alpha in a patient with MAS. Denaturing gradient gel electrophoresis was used to analyze amplified DNA fragments including exon 8 or exon 9 of the Gs alpha gene. In one subject with MAS a G-to-A transition was found in exon 8 of one of the two alleles encoding Gs alpha. This single-base substitution results in the replacement of arginine by histidine at position 201 of the mature Gs alpha protein. Semiquantitative analysis of amplified DNA indicated that the mutant allele was less prevalent than the wild-type allele in peripheral leukocytes and was present in very low levels in skin. These findings support the previous contention that the segmental distribution and variable expression of the cutaneous, skeletal, and endocrine manifestations of MAS reflect an underlying somatic mosaicism. Further, these results suggest that the molecular basis of MAS is a postzygotic mutation in Gs alpha that causes constitutive activation of adenylyl cyclase.

    Funded by: NIDDK NIH HHS: DK-34281

    Proceedings of the National Academy of Sciences of the United States of America 1992;89;11;5152-6

  • Activating mutations of the stimulatory G protein in the McCune-Albright syndrome.

    Weinstein LS, Shenker A, Gejman PV, Merino MJ, Friedman E and Spiegel AM

    Molecular Pathophysiology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892.

    Background: The McCune-Albright syndrome is a sporadic disease characterized by polyostotic fibrous dysplasia, café au lait spots, sexual precocity, and hyperfunction of multiple endocrine glands. These manifestations may be explained by a somatic mutation in affected tissues that results in activation of the signal-transduction pathway generating cyclic AMP (cAMP). We analyzed DNA from tissues of patients with the McCune-Albright syndrome for the presence of activating mutations of the gene for the alpha subunit of the G protein (Gs alpha) that stimulates cAMP formation.

    Methods: Genomic DNA fragments encompassing regions (exons 8 and 9) previously found to contain activating missense mutations of the Gs alpha gene (gsp mutations) in sporadically occurring pituitary tumors were amplified in tissues from four patients with the McCune-Albright syndrome by the polymerase chain reaction. The amplified DNA was analyzed for mutations by denaturing gradient gel electrophoresis and allele-specific oligonucleotide hybridization.

    Results: We detected one of two activating mutations within exon 8 of the Gs alpha gene in tissues from all four patients, including affected endocrine organs (gonads, adrenal glands, thyroid, and pituitary) and tissues not classically involved in the McCune-Albright syndrome. In two of the patients, histidine was substituted for arginine at position 201 of Gs alpha, and in the other two patients cysteine was substituted for the same arginine residue. In each patient the proportion of cells affected varied from tissue to tissue. In two endocrine organs, the highest proportion of mutant alleles was found in regions of abnormal cell proliferation.

    Conclusions: Mutations within exon 8 of the Gs alpha gene that result in increased activity of the Gs protein and increased cAMP formation are present in various tissues of patients with the McCune-Albright syndrome. Somatic mutation of this gene early in embryogenesis could result in the mosaic population of normal and mutant-bearing tissues that may underlie the clinical manifestations of this disease.

    The New England journal of medicine 1991;325;24;1688-95

  • Mapping of the gene encoding the alpha subunit of the stimulatory G protein of adenylyl cyclase (GNAS1) to 20q13.2----q13.3 in human by in situ hybridization.

    Levine MA, Modi WS and O'Brien SJ

    Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.

    Funded by: NIDDK NIH HHS: DK34281

    Genomics 1991;11;2;478-9

  • Differential expression of novel Gs alpha signal transduction protein cDNA species.

    Swaroop A, Agarwal N, Gruen JR, Bick D and Weissman SM

    Department of Ophthalmology, University of Michigan, Kellogg Eye Center, Ann Arbor 48105.

    The Gs alpha guanine nucleotide-binding signal transduction protein is part of a heterotrimeric complex that is involved in the stimulation of adenylate cyclase upon activation of membrane receptors. We report the characterization of 16 Gs alpha cDNA clones isolated from the human adult retina and fetal eye libraries. Molecular heterogeneity in the 5'-region defines four novel Gs alpha cDNA species which are generated either by alternate splicing or by using alternative promoter. The novel exons upstream of exon 2 interrupt the highly conserved 'region A' in the Gs alpha polypeptide. Non-AUG codons in the novel 5'-exon can initiate translation of these Gs alpha species in vitro. Reverse transcription of total RNA coupled with polymerase chain reaction (RTPCR) using specific primers and in situ hybridization to mRNA in baboon tissue sections with a specific oligonucleotide probe show a high level of expression of these species in retina and brain but not in liver. Differential expression of alternatively spliced Gs alpha species suggests novel signal transducing pathways.

    Funded by: NCI NIH HHS: CA42556; NEI NIH HHS: EY07961

    Nucleic acids research 1991;19;17;4725-9

  • Glucagon induces disaggregation of polymer-like structures of the alpha subunit of the stimulatory G protein in liver membranes.

    Nakamura S and Rodbell M

    Signal Transduction Section, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.

    The hydrodynamic behavior of G alpha s, the alpha subunit of the stimulatory guanine nucleotide-binding regulatory protein (G protein), in octyl glucoside extracts of rat liver membranes was investigated. As was previously shown for G proteins similarly extracted from brain synaptoneurosomes, G alpha s behaved as polydisperse structures with S values higher than that of heterotrimeric G proteins. At concentrations of guanosine 5'-[gamma-thio]triphosphate (GTP[gamma S]) greater than 100 microM, incubation with membranes led to smaller structures having S values in the range of 4-5 S. Incubation of liver membranes with glucagon also caused a marked increase in structures having these S values; glucagon action required the presence of low concentrations of GTP[gamma S] (maximal, 10 microM), was rapid (within 10 sec), and was not observed with vasopressin, angiotensin II, or glucagon-(19-29). When G alpha s in its membrane-bound form was [32P]ADP-ribosylated by cholera toxin and the treated membranes were extracted with octyl glucoside, greater than 35% of the labeled G alpha s was found in material that sedimented through sucrose gradients and contained relatively low levels of immunoreactive G alpha s. Glucagon selectively converted the apparently large molecular weight structures to the 4-5 S structures in the presence of GTP[gamma S], even at 1 mM (the maximal effect of the nucleotide alone), when incubated with the toxin-treated membranes. These findings suggest that the glucagon receptor selectively interacts with polymer-like structures of G alpha s and that activation by GTP[gamma S] results in disaggregation. The role of the beta and gamma subunits of G proteins in the hormone-induced process is not clear since the polymer-like structures extracted with octyl glucoside are devoid of beta and gamma subunits.

    Proceedings of the National Academy of Sciences of the United States of America 1991;88;16;7150-4

  • Mutations of the Gs alpha-subunit gene in Albright hereditary osteodystrophy detected by denaturing gradient gel electrophoresis.

    Weinstein LS, Gejman PV, Friedman E, Kadowaki T, Collins RM, Gershon ES and Spiegel AM

    Molecular Pathophysiology Branch, National Institute of Diabetes, Digestive and Kidney Diseases, Bethesda, MD 20892.

    Affected members of most kindreds with Albright hereditary osteodystrophy have a partial deficiency of functional Gs, the guanine nucleotide-binding protein that stimulates adenylyl cyclase. By use of the polymerase chain reaction to amplify genomic fragments with the attachment of a high-melting G + C-rich region (GC clamp) and analysis of these fragments by denaturing gradient gel electrophoresis, heterozygous mutations in the Gs alpha-subunit gene were found in two kindreds. These included a G----C substitution at the donor splice junction of intron 10 and a coding frameshift created by a single base deletion within exon 10. The findings illustrate the heterogeneity of genetic defects in Albright hereditary osteodystrophy and the usefulness of the polymerase chain reaction-denaturing gradient gel electrophoresis method to search rapidly for mutations in a large candidate gene.

    Proceedings of the National Academy of Sciences of the United States of America 1990;87;21;8287-90

  • Mutation in the gene encoding the stimulatory G protein of adenylate cyclase in Albright's hereditary osteodystrophy.

    Patten JL, Johns DR, Valle D, Eil C, Gruppuso PA, Steele G, Smallwood PM and Levine MA

    Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.

    Albright's hereditary osteodystrophy is an autosomal dominant disorder characterized by a short stature, brachydactyly, subcutaneous ossifications, and reduced expression or function of the alpha subunit of the stimulatory G protein (Gs alpha) of adenylate cyclase, which is necessary for the action of parathyroid and other hormones that use cyclic AMP as an intracellular second messenger. We identified a unique Gs alpha protein in erythrocytes from two related patients with Albright's hereditary osteodystrophy and reduced Gs alpha bioactivity. The Gs alpha variant was recognized by a carboxyl terminal-specific Gs alpha antiserum but not by polyclonal antiserums specific for the amino terminus of Gs alpha. To investigate the molecular basis for this structurally abnormal Gs alpha protein, we studied the Gs alpha gene by restriction-endonuclease analysis. DNA from the two patients had an abnormal restriction-fragment pattern when digested with Ncol, which was consistent with loss of an Ncol restriction site in exon 1 of one Gs alpha allele. Amplification of a 260-base-pair region that includes exon 1 of the Gs alpha gene and direct sequencing of the amplified DNA revealed an A-to-G transition at position +1 in one Gs alpha allele from each of the two patients. This mutation converts the initiator ATG (methionine) codon to GTG (valine), blocking initiation of translation at the normal site. Translation of the abnormal Gs alpha messenger RNA would result in the synthesis of a truncated Gs alpha molecule lacking the amino terminus. We conclude that in at least some patients with Albright's hereditary osteodystrophy, the disease is caused by a single-base substitution in the Gs alpha gene and is thus due to an inherited mutation in a human G protein.

    Funded by: NIDDK NIH HHS: DK-34281

    The New England journal of medicine 1990;322;20;1412-9

  • GTPase inhibiting mutations activate the alpha chain of Gs and stimulate adenylyl cyclase in human pituitary tumours.

    Landis CA, Masters SB, Spada A, Pace AM, Bourne HR and Vallar L

    Department of Pharmacology, University of California, San Francisco 94143.

    A subset of growth hormone-secreting human pituitary tumours carries somatic mutations that inhibit GTPase activity of a G protein alpha chain, alpha(s). The resulting activation of adenylyl cyclase bypasses the cells' normal requirement for trophic hormone. Amino acids substituted in the putative gsp oncogene identify a domain of G protein alpha-chains required for intrinsic ability to hydrolyse GTP. This domain may serve as a built-in counter-part of the separate GTPase-activating proteins required for GTP hydrolysis by small GTP-binding proteins such as p21ras.

    Nature 1989;340;6236;692-6

  • Complete cDNA sequence of a human stimulatory GTP-binding protein alpha subunit.

    Harris BA

    Merrell Dow Research Institute, Strasbourg, France.

    Nucleic acids research 1988;16;8;3585

  • Isolation and characterization of the human Gs alpha gene.

    Kozasa T, Itoh H, Tsukamoto T and Kaziro Y

    Institute of Medical Science, University of Tokyo, Japan.

    Proceedings of the National Academy of Sciences of the United States of America 1988;85;7;2081-5

  • Human cDNA clones for four species of G alpha s signal transduction protein.

    Bray P, Carter A, Simons C, Guo V, Puckett C, Kamholz J, Spiegel A and Nirenberg M

    lambda gt11 cDNA libraries derived from human brain were screened with oligonucleotide probes for recombinants that code for alpha subunits of G signal transduction proteins. Eleven alpha s clones were detected with both probes and characterized. Four types of alpha s cDNA were cloned that differ in nucleotide sequence in the region that corresponds to amino acid residues 71-88. The clones differ in the codon for alpha s amino acid residue 71 (glutamic acid or aspartic acid), the presence or absence of codons for the next 15 amino acid residues, and the presence or absence of an adjacent serine residue. S1 nuclease protection experiments revealed at least two forms of alpha s mRNA. A mechanism for generating four species of alpha s mRNA by alternative splicing of precursor RNA is proposed.

    Proceedings of the National Academy of Sciences of the United States of America 1986;83;23;8893-7

  • Identification by molecular cloning of two forms of the alpha-subunit of the human liver stimulatory (GS) regulatory component of adenylyl cyclase.

    Mattera R, Codina J, Crozat A, Kidd V, Woo SL and Birnbaumer L

    Two DNA molecules complementary to human liver mRNA coding for the alpha-subunit of the stimulatory regulatory component Gs of adenylyl cyclase were cloned. One of the two forms is a full-length cDNA of 1614 nucleotides plus a poly(A) tail of 59 nucleotides. The deduced sequence of 394 amino acids encoded by its open reading frame is essentially identical to that of the alpha-subunits of Gs identified by molecular cloning from bovine adrenals, bovine brain and rat brain. Two independent clones of the other type of cDNA were isolated. Both were incomplete, beginning within the open reading frame coding for the alpha s polypeptide. One codes for amino acids 5 through 394 and the other for amino acids 48 through 394 of the above described cDNA of 1614 nucleotides, and both have the identical 3'-untranslated sequence. They differ from the first cDNA, however, in that they lack a stretch of 42 nucleotides (numbers 214 through 255) and have nucleotides 213 (G) and 256 (G) replaced with C and A, respectively. This results in a predicted amino acid composition of another alpha-subunit of Gs that is shorter by 14 amino acids and contains two substitutions (Asp for Glu and Ser for Gly) at the interface between the deletion and the unchanged sequence. We call the smaller subunit alpha s1 and the larger alpha s2. This is the first demonstration of a structural heterogeneity in alpha s subunits that is due to a difference in amino acid sequence.

    Funded by: NIADDK NIH HHS: AM-19318, AM-27685; NICHD NIH HHS: HD-09581; ...

    FEBS letters 1986;206;1;36-42

  • Olfactory dysfunction in humans with deficient guanine nucleotide-binding protein.

    Weinstock RS, Wright HN, Spiegel AM, Levine MA and Moses AM

    The guanine nucleotide-binding stimulatory protein (Gs) couples hormone-receptor interaction to the activation of adenylate cyclase and the generation of cyclic AMP. Studies using frog neuroepithelium indicate that the sense of smell is mediated by a Gs-adenylate cyclase system, and this prompted us to test olfaction in the only known model of Gs deficiency in the animal kingdom, Gs-deficient (type 1a) pseudohypoparathyroidism (PHP), which occurs in humans. Such patients are resistant to the cAMP-mediated actions of several hormones. (Although Henkin has reported disturbances in the sense of smell in six patients with PHP, currently available biochemical measurements such as the cAMP response to parathyroid hormone (PTH) and determination of Gs activity were not reported and olfactory testing was limited.) In the present study, we found that all Gs-deficient patients had impaired olfaction when compared with PHP patients who had normal Gs activity (type 1b PHP, in which patients are resistant only to the action of PTH in the kidney). This is the first evidence of human olfactory impairment which can be related to Gs deficiency and suggests that Gs-deficient PHP patients may be resistant to cAMP-mediated actions in other non-endocrine systems.

    Funded by: NCRR NIH HHS: RR-229, RR-35; NINDS NIH HHS: NS 19568

    Nature 1986;322;6080;635-6

Gene lists (8)

Gene List Source Species Name Description Gene count
L00000009 G2C Homo sapiens Human PSD Human orthologues of mouse PSD adapted from Collins et al (2006) 1080
L00000015 G2C Homo sapiens Human NRC Human orthologues of mouse NRC adapted from Collins et al (2006) 186
L00000016 G2C Homo sapiens Human PSP Human orthologues of mouse PSP adapted from Collins et al (2006) 1121
L00000033 G2C Homo sapiens Pocklington H2 Human orthologues of cluster 2 (mouse) from Pocklington et al (2006) 13
L00000059 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-CONSENSUS Human cortex PSD consensus 748
L00000061 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus (ortho) 984
L00000069 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-FULL Human cortex biopsy PSD full list 1461
L00000071 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list (ortho) 1556
© G2C 2014. The Genes to Cognition Programme received funding from The Wellcome Trust and the EU FP7 Framework Programmes:
EUROSPIN (FP7-HEALTH-241498), SynSys (FP7-HEALTH-242167) and GENCODYS (FP7-HEALTH-241995).

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