G2Cdb::Gene report

Gene id
G00001697
Gene symbol
ACAT1 (HGNC)
Species
Homo sapiens
Description
acetyl-CoA acetyltransferase 1
Orthologue
G00000448 (Mus musculus)

Databases (7)

Gene
ENSG00000075239 (Ensembl human gene)
38 (Entrez Gene)
803 (G2Cdb plasticity & disease)
ACAT1 (GeneCards)
Literature
607809 (OMIM)
Marker Symbol
HGNC:93 (HGNC)
Protein Sequence
P24752 (UniProt)

Synonyms (1)

  • THIL

Literature (41)

Pubmed - other

  • Leptin modulates ACAT1 expression and cholesterol efflux from human macrophages.

    Hongo S, Watanabe T, Arita S, Kanome T, Kageyama H, Shioda S and Miyazaki A

    Department of Biochemistry, Showa University School of Medicine, Tokyo, Japan. shongo@med.showa-u.ac.jp

    Leptin is an adipose tissue-derived hormone implicated in atherosclerosis and macrophage foam cell formation. The current study was conducted to examine the effect of leptin on cholesteryl ester accumulation in human monocytes/macrophages. Exogenously added leptin at 5 nM during differentiation of monocytes into macrophages for 7 days accelerated acetylated LDL (acetyl-LDL)-induced cholesteryl ester accumulation by 30-50%. Leptin did not affect endocytic uptake of acetyl-LDL; however, it increased ACAT activity 1.8-fold and ACAT-1 protein expression 1.9-fold. Among the four ACAT-1 mRNA transcripts, two shorter transcripts (2.8 and 3.6 kb) were upregulated approximately 1.7-fold upon leptin treatment. The enhanced expression of ACAT-1 protein by leptin was suppressed by inhibitors of Janus-activated kinase2 (JAK2) and phosphatidylinositol 3-kinase (PI3K). HDL-mediated cholesterol efflux was suppressed by leptin, which was canceled by K-604, an ACAT-1 inhibitor. Expression of long form of leptin receptor was upregulated during monocytic differentiation into macrophages and sustained after differentiation. Thus, the results suggest that leptin accelerates cholesteryl ester accumulation in human monocyte-derived macrophages by increasing ACAT-1 expression via JAK2 and PI3K, thereby suppressing cholesterol efflux.

    American journal of physiology. Endocrinology and metabolism 2009;297;2;E474-82

  • Study of the insulin signaling pathways in the regulation of ACAT1 expression in cultured macrophages.

    Xin C, Yan-Fu W, Ping H, Jing G, Jing-Jing W, Chun-Li M, Wei L and Bei C

    Geriatric Department, Renmin Hospital of Wuhan University, Wuhan, China.

    Objective: To determine the signaling pathways and components involved in insulin-mediated regulation of Acyl-CoA: cholesterol acyltransferase1 (ACAT1).

    Methods: THP-1 cells were cultured in RPMI 1640 medium and were induced into macrophages in the presence of 160 nM phorbol 12-myristate 13-acetate (PMA). Before insulin was added in, macrophages were preincubated with the inhibitors of the insulin signaling pathway, including wortmannin, phosphatidylinositol 3-kinase (PI3K) inhibitor; PD98059, extracellular signal-regulated kinase (ERK) inhibitor; SB203580, p38 mitogen-activated protein kinase (p38MAPK) inhibitor; SP600125, c-Jun N-terminal kinase (JNK) inhibitor and U73122, phospholipase C-gamma (PLC-gamma) inhibitor. ACAT1 mRNA and protein expression level in macrophages were determined by real-time quantitative polymerase chain reaction and western blotting, respectively.

    Results: Real-time quantitative polymerase chain reaction and western blotting demonstrated that PD98059, SB203580 or SP600125 down-regulated the expression of ACAT1 in a dose-dependent manner. However, no obvious alteration was found in wortmannin and U73122 groups.

    Conclusion: These results suggest that the ERK, p38MAPK and JNK signaling pathways may be involved in insulin-mediated regulation of ACAT1, but no PI3K and PLC-gamma signaling pathways were involved in the present study.

    Cell biology international 2009;33;5;602-6

  • Docosahexaenoic acid is a substrate for ACAT1 and inhibits cholesteryl ester formation from oleic acid in MCF-10A cells.

    Antalis CJ, Arnold T, Lee B, Buhman KK and Siddiqui RA

    Cellular Biochemistry Laboratory, Methodist Research Institute, 1800 N. Capitol Avenue, Suite E504, Indianapolis, IN 46202, USA. cantalis@clarian.org

    MCF-10A breast epithelial cells treated with docosahexaenoic acid (DHA) or oleic acid (OA) accumulated cytoplasmic lipid droplets containing both triacylglycerol and cholesteryl esters (CE). Interestingly, total CE mass was reduced in cells treated with DHA compared to cells treated with OA, and the CEs were rich in n-3 fatty acids. Thus, we hypothesized that DHA may be, in addition to a substrate, an inhibitor of cholesterol esterification in MCF-10A cells. We determined that the primary isoform of acyl-CoA: cholesterol acyltransferase expressed in MCF-10A cells is ACAT1. We investigated CE formation with DHA, OA, and the combination in intact cells and isolated microsomes. In both cells and microsomes, the rate of CE formation was faster and more CE was formed with OA compared to DHA. DHA substantially reduced CE formation when given in combination with OA. These data suggest for the first time that DHA can act as a substrate for ACAT1. In the manner of a poor substrate, DHA also inhibited the activity of ACAT1, a universally expressed enzyme involved in intracellular cholesterol homeostasis, in a cell type that does not secrete lipids or express ACAT2.

    Prostaglandins, leukotrienes, and essential fatty acids 2009;80;2-3;165-71

  • Physiogenomic comparison of edema and BMI in patients receiving rosiglitazone or pioglitazone.

    Ruaño G, Bernene J, Windemuth A, Bower B, Wencker D, Seip RL, Kocherla M, Holford TR, Petit WA and Hanks S

    Genomas, Inc., 67 Jefferson St, Hartford, CT, United States. g.ruano@genomas.net

    Background: The thiazolidinediones (TZDs) improve tissue sensitivity to insulin in patients with type II diabetes, resulting in reduced levels of fasting blood glucose and glycated hemoglobin. However, TZDs unpredictably demonstrate adverse effects of increased body weight, fluid retention, and edema. The balance of efficacy and safety of TZD varies widely from patient to patient. Genetic variability may reveal pathophysiological pathways underlying weight gain associated with TZD therapy and due to adiposity and/or edema.

    Methods: We analyzed 384 single nucleotide polymorphisms (SNPs) from 222 cardiovascular and metabolic genes in 87 outpatients with type 2 diabetes receiving thiazolidinedione therapy. Physiogenomic analysis was used to discover associations with body mass index (BMI) and edema.

    Results: The 5 most significant gene associations found between BMI and SNPs were ADORA1, adenosine A1 receptor (rs903361, p<0.0003), PKM2, pyruvate kinase-muscle (rs2856929, p<0.002); ADIPOR2, adiponectin receptor 2 (rs7975375, p<0.007); UCP2, uncoupling protein 2 (rs660339, p<0.008); and APOH, apolipoprotein H (rs8178847, p<0.010). For edema, the 5 most significant gene associations were NPY, neuropeptide Y (rs1468271, p<0.006); GYS1, glycogen synthase 1-muscle (rs2287754, p<0.013); CCL2, chemokine C-C motif ligand 2 (rs3760396, p<0.015); OLR1, oxidized LDL receptor 1 (rs2742115, p<0.015); and GHRH, growth hormone releasing hormone (rs6032470, p<0.023). After accounting for multiple comparisons, ADORA1 was significantly associated with BMI at a false discovery rate (FDR) of <10%.

    Conclusion: Physiogenomic associations were discovered suggesting mechanistic links between adenosine signaling and BMI, and between vascular permeability and drug-induced edema.

    Clinica chimica acta; international journal of clinical chemistry 2009;400;1-2;48-55

  • Angiotensin II upregulates acyl-CoA:cholesterol acyltransferase-1 via the angiotensin II Type 1 receptor in human monocyte-macrophages.

    Kanome T, Watanabe T, Nishio K, Takahashi K, Hongo S and Miyazaki A

    Department of Biochemistry, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, Japan.

    Angiotensin II (Ang II) is known to accelerate the progression of macrophage-driven atherosclerotic lesions. Acyl-CoA:cholesterol acyltransferase-1 (ACAT1) converts intracellular free cholesterol into cholesterol ester (CE) for storage in lipid droplets, and promotes foam cell formation in atherosclerotic lesions. The present study explored the effect of Ang II on ACAT1 expression as a molecular mechanism of foam cell formation in primary cultured human monocyte-macrophages. Ang II significantly increased ACAT1 protein expression in a time- or concentration-dependent manner. Application of an Ang II type 1 (AT(1)) receptor agonist (L162313), but not an Ang II type 2 (AT(2)) receptor agonist (CGP42112A), mimicked the effects of Ang II treatment in inducing ACAT1 protein expression. ACAT activity and ACAT1 mRNA levels were also significantly increased by Ang II. Two-fold increases in ACAT1 protein expression and ACAT activity with Ang II treatment were completely inhibited by AT(1) receptor antagonists (candesartan, [Sar(1),Ile(8)]-Ang II), but not by an AT(2) receptor antagonist (PD123319). Treatment with a G-protein inactivator (GDP-beta-S), a c-Src tyrosine kinase inhibitor (PP2), a protein kinase C (PKC) inhibitor (rottlerin), or a mitogen activated protein kinase (MAPK) kinase inhibitor (PD98059) significantly reduced Ang II-induced ACAT1 protein expression. Macrophage foam cell formation assessed using acetylated low-density lipoprotein (LDL)-induced CE accumulation was significantly enhanced by Ang II, which was completely inhibited by treatment with candesartan. These results suggested that Ang II enhances foam cell formation by upregulating ACAT1 expression predominantly through the actions of AT(1) receptor via the G protein/c-Src/PKC/MAPK pathway in human monocyte-macrophages.

    Hypertension research : official journal of the Japanese Society of Hypertension 2008;31;9;1801-10

  • [Genetic predisposition to systemic complications of arterial hypertension in maintenance haemodialysis patients].

    Bzoma B, Debska-Slizień A, Dudziak M, Raczyńska K, Slizień W, Brylowska A and Rutkowski B

    Klinika Nefrologii, Transplantologii i Chorób Wewnetrznych. bbzoma@mp.pl

    Unlabelled: Cardiovascular disease is the most common cause of a high morbidity and mortality in patients on renal replacement therapy and is responsible for about 50% of deaths. Hypertension is the main risk factor for cardiovascular events in the general population as well as in haemodialysed (HD) patients. The hypertension in HD patients is caused by excess extracellular fluid volume (ECV) on the other hand hypertension resistant to normalization of ECV may result from the accelerated activity of the systemic and local--vascular renin-angiotensin-aldosteron system (RAAS). RAAS genes are potential etiological candidates for cardiovascular damage. The aim of the study was to evaluate the prevalence of hypertension, left ventricular hypertrophy, hypertensive retinopathy in patients treated with haemodialysis and to evaluate the association between the polymorphism of RAAS genes: ACE I/D, AGT M235T AT1R A1166C, CYP112 (-344) and the systemic complications of arterial hypertension such as hypertensive retinopathy, left ventricular hypertrophy and also mortality in haemodialysis patients.

    The studied population consisted of 302 HD patients (175 men, 127 women) age 21-87, mean 56, at four dialysis units. Patients with cardiac defect, advanced coronary artery disease and atrial fibrillation were excluded from the study. 62 patients died during 3,5 years of observation. Methods consisted of tree times repeated blood pressure measurements before and post dialysis, echocardiography, direct opthalmoscopy (Keith-Wegener-Barker classification of hypertensive retinopathy) and DNA analysis--genotypes ACE I/D, AGT M235T AT1R A1166C, CYP11B2 T(-344)C were determined through PCR or PCR-RFLP method.

    Results: Hypertension was present in 72%, LVH in 84% haemodialysed patients. Arterial pressure correlated with LVMI values and hypertension was connected with LVH. Insufficient control of blood pressure and LVH were connected with worse survival in HD patients.

    Conclusions: It seems that I/D polymorphism ACE gene and AC AT1 gene influence the development of hypertension and LVH in HD patients. The most dangerous in the development of hypertension and LVH was DD genotype ACE gene and CC AT1 gene. ACE I/D, AGT M/T, AT1 A/C, CYP11B2 T/C polymorphism appears to have no relation to the short-term prognosis in HD patients. The mortality did not differ among groups with different genotypes of ACE I/D, AGT M/T AT1 A/C, CYP11B2 T/C polymorphisms. Direct ophtalmoscopy seems to be an insufficient method in the estimation of the systemic complications of hypertension in haemodialysed patients.

    Polski merkuriusz lekarski : organ Polskiego Towarzystwa Lekarskiego 2008;25;147;209-16

  • RNA secondary structures located in the interchromosomal region of human ACAT1 chimeric mRNA are required to produce the 56-kDa isoform.

    Chen J, Zhao XN, Yang L, Hu GJ, Lu M, Xiong Y, Yang XY, Chang CC, Song BL, Chang TY and Li BL

    State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.

    We have previously reported that the human ACAT1 gene produces a chimeric mRNA through the interchromosomal processing of two discontinuous RNAs transcribed from chromosomes 1 and 7. The chimeric mRNA uses AUG(1397-1399) and GGC(1274-1276) as translation initiation codons to produce normal 50-kDa ACAT1 and a novel enzymatically active 56-kDa isoform, respectively, with the latter being authentically present in human cells, including human monocyte-derived macrophages. In this work, we report that RNA secondary structures located in the vicinity of the GGC(1274-1276) codon are required for production of the 56-kDa isoform. The effects of the three predicted stem-loops (nt 1255-1268, 1286-1342 and 1355-1384) were tested individually by transfecting expression plasmids into cells that contained the wild-type, deleted or mutant stem-loop sequences linked to a partial ACAT1 AUG open reading frame (ORF) or to the ORFs of other genes. The expression patterns were monitored by western blot analyses. We found that the upstream stem-loop(1255-1268) from chromosome 7 and downstream stem-loop(1286-1342) from chromosome 1 were needed for production of the 56-kDa isoform, whereas the last stem-loop(1355-1384) from Chromosome 1 was dispensable. The results of experiments using both monocistronic and bicistronic vectors with a stable hairpin showed that translation initiation from the GGC(1274-1276) codon was mediated by an internal ribosome entry site (IRES). Further experiments revealed that translation initiation from the GGC(1274-1276) codon requires the upstream AU-constituted RNA secondary structure and the downstream GC-rich structure. This mechanistic work provides further support for the biological significance of the chimeric nature of the human ACAT1 transcript.

    Funded by: NHLBI NIH HHS: HL 36709, R01 HL036709, R01 HL036709-23, R37 HL036709

    Cell research 2008;18;9;921-36

  • Inhibition of acyl-coenzyme A:cholesterol acyltransferase stimulates cholesterol efflux from macrophages and stimulates farnesoid X receptor in hepatocytes.

    An S, Jang YS, Park JS, Kwon BM, Paik YK and Jeong TS

    National Research Laboratory of Lipid Metabolism and Atherosclerosis, KRIBB, Daejeon, Korea.

    We investigated the mechanism of spontaneous cholesterol efflux induced by acyl-coenzyme A:cholesterol acyltransferase (ACAT) inhibition, and how an alteration of cholesterol metabolism in macrophages impacts on that in HepG2 cells. Oleic acid anilide (OAA), a known ACAT inhibitor reduced lipid storage substantially by promotion of cholesterol catabolism and repression of cholesteryl ester accumulation without further increase of cytotoxicity in acetylated low-density lipoprotein-loaded THP-1 macrophages. Analysis of expressed mRNA and protein revealed that cholesterol 7alpha-hydroxylase (CYP7A1), oxysterol 7alpha- hydroxylase (CYP7B1), and cholesterol 27-hydroxylase (CYP27) were highly induced by ACAT inhibition. The presence of a functional cytochrome P450 pathway was confirmed by quantification of the biliary cholesterol mass in cell monolayers and extracelluar medium. Notably, massively secreted biliary cholesterol from macrophages suppressed the expression of CYP7 proteins in a farnesoid X receptor (FXR)-dependent manner in HepG2 cells. The findings reported here provide new insight into mechanisms of spontaneous cholesterol efflux, and suggest that ACAT inhibition may stimulate cholesterol-catabolic (cytochrome P450) pathway in lesion-macrophages, in contrast, suppress it in hepatocyte via FXR induced by biliary cholesterol (BC).

    Experimental & molecular medicine 2008;40;4;407-17

  • The catalytic and lectin domains of UDP-GalNAc:polypeptide alpha-N-Acetylgalactosaminyltransferase function in concert to direct glycosylation site selection.

    Raman J, Fritz TA, Gerken TA, Jamison O, Live D, Liu M and Tabak LA

    Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA.

    UDP-GalNAc:polypeptide alpha-N-Acetylgalactosaminyltransferases (ppGalNAcTs), a family (EC 2.4.1.41) of enzymes that initiate mucin-type O-glycosylation, are structurally composed of a catalytic domain and a lectin domain. Previous studies have suggested that the lectin domain modulates the glycosylation of glycopeptide substrates and may underlie the strict glycopeptide specificity of some isoforms (ppGalNAcT-7 and -10). Using a set of synthetic peptides and glycopeptides based upon the sequence of the mucin, MUC5AC, we have examined the activity and glycosylation site preference of lectin domain deletion and exchange constructs of the peptide/glycopeptide transferase ppGalNAcT-2 (hT2) and the glycopeptide transferase ppGalNAcT-10 (hT10). We demonstrate that the lectin domain of hT2 directs glycosylation site selection for glycopeptide substrates. Pre-steady-state kinetic measurements show that this effect is attributable to two mechanisms, either lectin domain-aided substrate binding or lectin domain-aided product release following glycosylation. We find that glycosylation of peptide substrates by hT10 requires binding of existing GalNAcs on the substrate to either its catalytic or lectin domain, thereby resulting in its apparent strict glycopeptide specificity. These results highlight the existence of two modes of site selection used by these ppGalNAcTs: local sequence recognition by the catalytic domain and the concerted recognition of distal sites of prior glycosylation together with local sequence binding mediated, respectively, by the lectin and catalytic domains. The latter mode may facilitate the glycosylation of serine or threonine residues, which occur in sequence contexts that would not be efficiently glycosylated by the catalytic domain alone. Local sequence recognition by the catalytic domain differs between hT2 and hT10 in that hT10 requires a pre-existing GalNAc residue while hT2 does not.

    Funded by: Intramural NIH HHS; NCI NIH HHS: NCI-R01 CA-78834, R01 CA078834; PHS HHS: NIGMS-R01 GM-066148

    The Journal of biological chemistry 2008;283;34;22942-51

  • A novel single-base substitution (c.1124A>G) that activates a 5-base upstream cryptic splice donor site within exon 11 in the human mitochondrial acetoacetyl-CoA thiolase gene.

    Fukao T, Boneh A, Aoki Y and Kondo N

    Department of Pediatrics, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu 501-1194, Japan. address: toshi-gif@umim.net

    Most mutations related to aberrant splicing occur in conserved splice acceptor and donor sites. Some exonic mutations also affect splicing. We identified and characterized a point mutation (c.1124A>G) in an Australian patient (GK43) with mitochondrial acetoacetyl-CoA thiolase (T2) deficiency. GK43 is a homozygote of c.1124A>G, which activates a cryptic splice donor site 5 bases upstream from c.1124A>G within exon 11, causing aberrant splicing in most transcripts. The aberrant splicing results in c.1120-1163 (44-base) deletion, causing a frameshift in T2 mRNA. A mini-gene splicing experiment confirmed that the c.1124A>G substitution was responsible for this aberrant splicing. This cryptic splice site has a Shapiro and Senapathy score (70.0) in a normal sequence but if mutated, the score (84.3) becomes higher than the one in the authentic splice donor site of intron 11 (81.4). This is an example in which a point mutation activates a cryptic splice donor site motif that is used preferentially over a downstream authentic splice site.

    Molecular genetics and metabolism 2008;94;4;417-21

  • [Analysis of acyl-coenzyme A: cholesterol acyltransferase 1 polymorphism in patients with endogenous hypertriglyceridemia in Chinese population].

    Li Q, Bai H and Fan P

    Unit of Laboratory Medicine, West China Second Hospital, Sichuan University, Chengdu, Sichuan, 610041 P. R. China. baihuai@hotmail.com.

    Objective: To investigate the polymorphism of acyl-coenzyme A: cholesterol acyltransferase 1(ACAT1) gene and its relationship with endogenous hypertriglyceridemia (HTG) in Chinese population.

    Methods: A total of three hundred and seventy-two subjects (105 endogenous hypertriglyceridemics and 267 healthy controls) from a population of Chinese Han nationality in Chengdu area were studied using PCR-restriction fragment length polymorphism (RFLP).

    Results: The frequency of C allele in normal Chinese at rs1044925 locus was 0.137, which was lower than that reported in the population of central and Southern Europe (0.354) (P< 0.05). The frequency C allele was 0.153 in HTG group. No significant difference between normal control and HTG group. In control group, subjects with genotype AA had a higher serum mean concentrations of low density lipoprotein-cholesterol (LDL-C) and non-high density lipoprotein-cholesterol(nHDL-C) when compared with those of C allele carriers (AC and CC genotype carriers), respectively [(3.25+/- 0.68) mmol/L vs (3.03+/- 0.87) mmol/L, P< 0.05; (3.80+/- 0.71) mmol/L vs (3.23+/- 0.82) mmol/L, P< 0.05]. In HTG group, subjects with genotype AA had a higher high density lipoprotein-cholesterol (HDL-C) level compared with those of C allele carriers [(1.00+/- 0.28) mmol/L vs (0.87+/- 0.17) mmol/L, P< 0.05].

    Conclusion: These results suggest that rs1044925 polymorphism in ACAT1 gene is not only associated with serum LDL-C and nHDLC levels in healthy Chinese subjects in Chengdu area, but also with HDL-C level in subjects with endogenous hypertriglyceridemia in this population.

    Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 2008;25;2;206-10

  • Toward a confocal subcellular atlas of the human proteome.

    Barbe L, Lundberg E, Oksvold P, Stenius A, Lewin E, Björling E, Asplund A, Pontén F, Brismar H, Uhlén M and Andersson-Svahn H

    Department of Biotechnology, AlbaNova University Center, Royal Institute of Technology, SE-106 91 Stockholm, Sweden.

    Information on protein localization on the subcellular level is important to map and characterize the proteome and to better understand cellular functions of proteins. Here we report on a pilot study of 466 proteins in three human cell lines aimed to allow large scale confocal microscopy analysis using protein-specific antibodies. Approximately 3000 high resolution images were generated, and more than 80% of the analyzed proteins could be classified in one or multiple subcellular compartment(s). The localizations of the proteins showed, in many cases, good agreement with the Gene Ontology localization prediction model. This is the first large scale antibody-based study to localize proteins into subcellular compartments using antibodies and confocal microscopy. The results suggest that this approach might be a valuable tool in conjunction with predictive models for protein localization.

    Molecular & cellular proteomics : MCP 2008;7;3;499-508

  • Androgen-mediated cholesterol metabolism in LNCaP and PC-3 cell lines is regulated through two different isoforms of acyl-coenzyme A:Cholesterol Acyltransferase (ACAT).

    Locke JA, Wasan KM, Nelson CC, Guns ES and Leon CG

    Department of Urologic Sciences, University of British Columbia, The Prostate Centre at Vancouver General Hospital, Vancouver, British Columbia, Canada.

    Background: The objective of this work was to determine the effect of an androgen agonist, R1881, on intracellular cholesterol synthesis and esterification in androgen-sensitive (AS) prostate cancer (LNCaP) cells.

    Methods: We investigated the activity and expression of cholesterol metabolism enzymes, HMG-CoA-reductase and ACAT in the LNCaP and PC-3 (androgen-independent control) models.

    Results: Microsomal PC-3 HMG-CoA-reductase activity was increased with R1881 despite having similar cholesterol levels while increased cholesterol levels in microsomes from LNCaPs treated with R1881 (L+) were associated with increased HMG-CoA reductase activity. Increased intracellular cholesteryl esters (CE) found in (L+) were not associated with an increased ACAT1 activity. There was no effect from androgen treatment on ACAT1 protein expression in theses cells; however, ACAT2 expression was induced upon R1881 treatment. In contrast, we found an increase in the in vitro ACAT1 activity in PC-3 cells treated with androgen (P+). Only ACAT1 expression was induced in P+. We further assessed the expression of STAT1 alpha, a transcriptional activator that modulates ACAT1 expression. STAT1 alpha expression and phosphorylation were induced in P+. To determine the role of the AR on ACAT1 expression and esterification, we treated PC-3 cells overexpressing the androgen receptor with R1881 (PAR+). AR expression was decreased in PAR+ cells; ACAT1 protein expression and cholesterol ester levels were also decreased, however, ACAT2 remained unchanged. STAT1 alpha expression was decreased in PAR+.

    Conclusions: Overall, these findings support the importance of cholesterol metabolism regulation within prostate cancer cells and unravel a novel role for STAT1 alpha in prostate cancer metabolism.

    The Prostate 2008;68;1;20-33

  • Functionality of the seventh and eighth transmembrane domains of acyl-coenzyme A:cholesterol acyltransferase 1.

    Guo ZY, Chang CC and Chang TY

    Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.

    Acyl-coenzyme A:cholesterol acyltransferase 1 (ACAT1) is a resident enzyme in the endoplasmic reticulum. ACAT1 is a homotetrameric protein and contains nine transmembrane domains (TMDs). His460 is a key active residue and is located within TMD7. Human ACAT1 has seven free Cys, but the recombinant ACAT1 devoid of free Cys retains full enzyme activity. To further probe the functionality of TMD7 (amino acids 446-460) and TMD8 (amino acids 466-481), we used a parental ACAT1 devoid of free Cys as the template to perform Cys-scanning mutagenesis within these regions. Each of the single Cys mutants was expressed in Chinese hamster ovary (CHO) cell line AC29 lacking endogenous ACAT1. We measured the effect of single Cys substitution on enzyme activity and used the Cu(1,10-phenanthroline)2SO4-mediated disulfide cross-linking method to probe possible interactions of engineered Cys between the two identical subunits. The results show that several residues in one subunit closely interact with the same residues in the other subunit; mutating these residues to Cys does not lead to large loss in enzyme activity. Helical wheel analysis suggests that these residues are located at one side of the coil. In contrast, mutating residues F453, A457, or H460 to Cys causes large loss in enzyme activity; the latter residues are located at the opposite side of the coil. A similar arrangement is found for residues in TMD8. Thus, helical coils in TMD7 and TMD8 have two distinct functional sides: one side is involved in substrate-binding/catalysis, while the other side is involved in subunit interaction.

    Funded by: NHLBI NIH HHS: HL60306

    Biochemistry 2007;46;35;10063-71

  • Crystallographic and kinetic studies of human mitochondrial acetoacetyl-CoA thiolase: the importance of potassium and chloride ions for its structure and function.

    Haapalainen AM, Meriläinen G, Pirilä PL, Kondo N, Fukao T and Wierenga RK

    Biocenter Oulu and Department of Biochemistry, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland.

    Thiolases are CoA-dependent enzymes which catalyze the formation of a carbon-carbon bond in a Claisen condensation step and its reverse reaction via a thiolytic degradation mechanism. Mitochondrial acetoacetyl-coenzyme A (CoA) thiolase (T2) is important in the pathways for the synthesis and degradation of ketone bodies as well as for the degradation of 2-methylacetoacetyl-CoA. Human T2 deficiency has been identified in more than 60 patients. A unique property of T2 is its activation by potassium ions. High-resolution human T2 crystal structures are reported for the apo form and the CoA complex, with and without a bound potassium ion. The potassium ion is bound near the CoA binding site and the catalytic site. Binding of the potassium ion at this low-affinity binding site causes the rigidification of a CoA binding loop and an active site loop. Unexpectedly, a high-affinity binding site for a chloride ion has also been identified. The chloride ion is copurified, and its binding site is at the dimer interface, near two catalytic loops. A unique property of T2 is its ability to use 2-methyl-branched acetoacetyl-CoA as a substrate, whereas the other structurally characterized thiolases cannot utilize the 2-methylated compounds. The kinetic measurements show that T2 can degrade acetoacetyl-CoA and 2-methylacetoacetyl-CoA with similar catalytic efficiencies. For both substrates, the turnover numbers increase approximately 3-fold when the potassium ion concentration is increased from 0 to 40 mM KCl. The structural analysis of the active site of T2 indicates that the Phe325-Pro326 dipeptide near the catalytic cavity is responsible for the exclusive 2-methyl-branched substrate specificity.

    Biochemistry 2007;46;14;4305-21

  • Kinetic and expression analyses of seven novel mutations in mitochondrial acetoacetyl-CoA thiolase (T2): identification of a Km mutant and an analysis of the mutational sites in the structure.

    Sakurai S, Fukao T, Haapalainen AM, Zhang G, Yamada K, Lilliu F, Yano S, Robinson P, Gibson MK, Wanders RJ, Mitchell GA, Wierenga RK and Kondo N

    Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Gifu, Japan.

    Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency is an inborn error of metabolism that affects isoleucine catabolism and ketone body metabolism. We identified 7 novel and 2 previously reported mutations in six T2-deficient patients. Transient expression analysis of wild-type and eight mutant cDNAs was performed at 40, 37 and 30 degrees C. Although no significant residual activity was detected, mutant proteins were detected in the N158D, N158S, R208Q, Y219H and N282H mutants. Accumulation of these mutant proteins was temperature-sensitive with the highest expression levels at lower temperatures. Expression of Q73P and N353K cDNAs yielded neither residual T2 protein nor enzyme activity. An E252del mutant T2 was detected with a relative protein amount and enzyme activity of 30% and 25%, respectively, in comparison to the wild-type at 37 degrees C. The E252del mutant protein was more stable at 30 degrees C expression than 37 degrees C, but was essentially undetectable at 40 degrees C, indicating its temperature-sensitive instability. Kinetic studies revealed a twofold K(m) elevation for substrates coenzyme A and acetoacetyl-CoA in the E252del mutant, while V(max) was comparable to the wild-type. We conclude that the E252del is a temperature-sensitive K(m) mutant. This correlates well with the effect predicted from the T2 tertiary structure analysis, using the crystal structure of the human T2 homotetramer. The probable effect of the other mutations on the T2 tertiary structure was also evaluated.

    Molecular genetics and metabolism 2007;90;4;370-8

  • 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

  • Identification of Alu-mediated, large deletion-spanning exons 2-4 in a patient with mitochondrial acetoacetyl-CoA thiolase deficiency.

    Zhang G, Fukao T, Sakurai S, Yamada K, Michael Gibson K and Kondo N

    Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Gifu 501-1194, Japan.

    Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency is a rare inherited metabolic disorder affecting isoleucine catabolism and ketone body metabolism. So far, more than 39 different mutations have been identified in 60 T2-deficient patients. However, no large deletions have been reported. We herein report the first case of a large T2 gene deletion from intron 1 to intron 4 in a T2-deficient patient (GK41). cDNA analysis revealed that an aberrant cDNA with exons 2-5 skipping was a major transcript, associated with a minor transcript of exons 2-4 skipping with a 94-bp insertion composed of an intron 1 sequence. Genomic analysis indicated an absence of PCR amplification of exons 2-4 and gene deletion was revealed by Southern blot analysis. Cloning and sequencing long range PCR products revealed a 6.4kb deletion. Alu element-mediated unequal homologous recombination between an Alu-Sx in intron 1 and another Alu-Y in intron 4 appears to be responsible for this deletion.

    Molecular genetics and metabolism 2006;89;3;222-6

  • Transcriptome analysis of human gastric cancer.

    Oh JH, Yang JO, Hahn Y, Kim MR, Byun SS, Jeon YJ, Kim JM, Song KS, Noh SM, Kim S, Yoo HS, Kim YS and Kim NS

    Laboratory of Human Genomics, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon , 305-333, Korea.

    To elucidate the genetic events associated with gastric cancer, 124,704 cDNA clones were collected from 37 human gastric cDNA libraries, including 20 full-length enriched cDNA libraries of gastric cancer cell lines and tissues from Korean patients. An analysis of the collected ESTs revealed that 97,930 high-quality ESTs coalesced into 13,001 clusters, of which 11,135 clusters (85.6%) were annotated to known ESTs. The analysis of the full-length cDNAs also revealed that 4862 clusters (51.7%) contained at least one putative full-length cDNA clone with an initiation codon, with the average length of the 5' UTR of 140 bp. A large number appear to have a diverse transcription start site (TSS). An examination of the TSS of some genes, such as TEGT and GAPD, using 5' RACE revealed that the predicted TSSs are actually found in human gastric cancer cells and that several TSSs differ depending on the specific gastric cell line. Furthermore, of the human gastric ESTs, 766 genes (9.5%) were present as putative alternatively spliced variants. Confirmation of the predicted spliced isoforms using RT-PCR showed that the predicted isoforms exist in gastric cancer cells and some isoforms coexist in gastric cell lines. These results provide potentially useful information for elucidating the molecular mechanisms associated with gastric oncogenesis.

    Mammalian genome : official journal of the International Mammalian Genome Society 2005;16;12;942-54

  • 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

  • Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency: T2-deficient patients with "mild" mutation(s) were previously misinterpreted as normal by the coupled assay with tiglyl-CoA.

    Zhang GX, Fukao T, Rolland MO, Zabot MT, Renom G, Touma E, Kondo M, Matsuo N and Kondo N

    departmentof Pediatrics, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1194, Japan.

    Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency is an inborn error of metabolism that affects the catabolism of isoleucine and ketone bodies. This disorder is characterized by intermittent ketoacidotic episodes. Recently, we diagnosed T2 deficiency in two patients (GK45 and GK47) by the absence of potassium ion-activated acetoacetyl-CoA thiolase activity, whereas these patients were previously misinterpreted as normal by a coupled assay with tiglyl-CoA as a substrate. This method has been widely used for the enzymatic diagnosis of the T2 deficiency in the United States and Europe. We hypothesized that some residual T2 activity showed normal results in the assay. To prove this hypothesis, we analyzed these two patients together with three typical T2-deficient patients (GK46, GK49, and GK50) at the DNA level. Expression analysis of mutant cDNAs clearly showed that GK45 and GK47 had "mild" mutations (A132G, D339-V340insD) that retained some residual T2 activity, at least one of two mutant alleles, whereas the other three patients had null mutations (c.52-53insC, G152A, H397D, and IVS8+1g>t) in either allele. These results raise the possibility that T2-deficient patients with mild mutations have been misinterpreted as normal by the coupled assay with tiglyl-CoA.

    Pediatric research 2004;56;1;60-4

  • The influence of the acyl-CoA:cholesterol acyltransferase-1 gene (-77G-->A) polymorphisms on plasma lipid and apolipoprotein levels in normolipidemic and hyperlipidemic subjects.

    Ohta T, Takata K, Katsuren K and Fukuyama S

    Department of Pediatrics, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0125, Japan. tohta@med.u-ryukyu.ac.jp

    Background: Acyl-CoA:cholesterol acyltransferase (ACAT) plays important roles in cellular cholesterol homeostasis. Two isoforms of ACAT have been reported (ACAT-1 and ACAT-2). ACAT inhibitors cannot only prevent atherosclerosis formation, but may also induce its regression in animals. In humans, an ACAT inhibitor was shown to have a lipid-lowering effect. The present study was carried out to clarify the relationship between ACAT-1 gene variants and hyperlipidemia.

    To identify genetic variants, we screened 30 subjects with hyperlipidemia by direct sequencing. As a result, a missense variant (R526G) and a variant in the 5' untranslated region (-77G-->A) were identified. The genotype frequencies of each variant were determined in 178 unrelated normolipidemic and 441 unrelated hyperlipidemic subjects. The alleles frequencies of the R526G variant in normolipidemic and hyperlipidemic subjects were 0.676 and 0.633, respectively. The alleles frequencies of the -77G-->A variant in normolipidemic and hyperlipidemic subjects were 0.503 and 0.515, respectively. Differences in allele frequencies between normolipidemic and hyperlipidemic subjects were not significant in both variants. R526G variant did not affect plasma concentrations of lipids or apolipoproteins in subjects studied. However, among hyperlipidemic subjects, plasma concentrations of HDL-C and apoA-I in subjects with -77G-->A variant were significantly higher than those in subjects without variant.

    Conclusion: Two variants in ACAT-1 gene were identified in subjects with hyperlipidemia. -77G-->A variant affects plasma HDL concentrations only in hyperlipidemic subjects. These data suggest that the intracellular FC concentration might modulate plasma HDL concentrations.

    Biochimica et biophysica acta 2004;1682;1-3;56-62

  • Single base substitutions at the initiator codon in the mitochondrial acetoacetyl-CoA thiolase (ACAT1/T2) gene result in production of varying amounts of wild-type T2 polypeptide.

    Fukao T, Matsuo N, Zhang GX, Urasawa R, Kubo T, Kohno Y and Kondo N

    Department of Pediatrics, Gifu University School of Medicine, Gifu, Japan. toshi-gif@umim.ac.jp

    Initiator codon mutations are relatively uncommon and less well characterized compared to other types of mutations. We identified a novel initiator codon mutation (c.2T>C) heterozygously in a Japanese patient (Patient GK30) with mitochondrial acetoacetyl-CoA thiolase (T2) gene deficiency (ACAT1 deficiency); c.149delC was on the other allele. We examined translation efficiencies of nine mutant T2 cDNAs harboring one-base substitutions at the initiator methionine codon using in vivo transient expression analysis. We found that all the mutants produced wild-type T2 polypeptide, to various degrees (wild type (100%) > c.1A>C (66%) > c.2T>C, c.3G>C, c.3G>T (22%) > c3G>A, c.1A>G (11%) > c.2T>A, c.2T>G, c.1A>T (7.4%)). T2 mRNA expression levels in Patient GK08 (a homozygote of c.2T>A) and Patient GK30 fibroblasts, respectively, were almost the same as in control fibroblasts, when examined using semiquantitative PCR. This means that initiator codon mutations did not affect T2 mRNA levels. We propose that all one-base substitutions at the initiator methionine codon in the T2 gene could be mutations, which retain some residual T2 activity.

    Human mutation 2003;21;6;587-92

  • Mitochondrial acetoacetyl-CoA thiolase (beta-ketothiolase) deficiency and pregnancy.

    Sewell AC, Herwig J, Wiegratz I, Lehnert W, Niederhoff H, Song XQ, Kondo N and Fukao T

    Department of Paediatrics, University of Frankfurt, Germany.

    Journal of inherited metabolic disease 1998;21;4;441-2

  • Practical assay method of cytosolic acetoacetyl-CoA thiolase by rapid release of cytosolic enzymes from cultured lymphocytes using digitonin.

    Watanabe H, Yamaguchi S, Kimura M, Wakazono A, Song XQ, Fukao T, Orii T and Hashimoto T

    Department of Pediatrics, Shimane Medical University, Izumo, Japan.

    We designed a simple approach to determine cytosolic acetoacetyl-CoA thiolase (CT) activity for differential diagnosis of ketone body catabolic defects, using rapid cell-subfractionation of cultured lymphocytes with digitonin. Efficiency of cell subfractionation was determined by measurement of lactate dehydrogenase and citrate synthetase as marker enzymes for cytosol and organelle fractions, respectively, and confirmed by immunotitration and immunoblotting using antibodies against cytosolic and mitochondrial thiolases, respectively. In the condition of best separation taken in the presence of 1 mg/ml digitonin, acetoacetyl-CoA thiolase activities in the presence of K+ ion in the cytosol and organelle fractions were 138.3+/-39.2 and 84.0+/-16.2 nmol/min/ml, respectively. The thiolase activity in the organelle fraction was doubled by the presence of K+ ion, whereas that in the cytosol fraction was not affected. The thiolase activity in the organelle fraction was reduced by the treatment of anti-mitochondrial acetoacetyl-CoA thiolase (T2) antibody but not by anti-CT antibody. On the other hand, that in the cytosol fraction was significantly decreased by anti-CT antibody but not by anti-T2 antibody. These data suggested that T2 was collected in the organelle fraction, and that CT activity could be assessed by measurement of the thiolase activity in the cytosolic fraction. Succinyl-CoA: 3-ketoacid CoA transferase (SCOT), whose defect is the third inherited disorder of ketone body catabolism, was collected in the organelle fraction. Hence, this method will prove to be useful for accurate assessment of defects of CT as well as T2 or SCOT, all involved in ketone body catabolism.

    The Tohoku journal of experimental medicine 1998;184;1;29-38

  • Characterization of N93S, I312T, and A333P missense mutations in two Japanese families with mitochondrial acetoacetyl-CoA thiolase deficiency.

    Fukao T, Nakamura H, Song XQ, Nakamura K, Orii KE, Kohno Y, Kano M, Yamaguchi S, Hashimoto T, Orii T and Kondo N

    Department of Pediatrics, Gifu University School of Medicine, Japan. toshi-gif@umim.u-tokyo.ac.jp

    Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency is an inborn error of ketone body and isoleucine catabolisms. Japanese patients, GK01 and GK19, were found to be compound heterozygotes of 149delC and A333P, and N93S and I312T, respectively. The latter three missense mutations were individually characterized by analyses of transient expression of the cDNAs and heat stability. A333P and I312T subunits showed aberrant electrophoretic mobility on SDS-PAGE. T2 protein was destabilized by A333P and existed as an insoluble form in the mitochondria. I312T mutation also destabilized T2 protein; however, some T2 protein was retained in soluble form and reduced residual activity was apparent. N93S mutation did not change the heat stability of T2 activity and the reduced residual activity was retained, however a considerable amount was observed in an insoluble form. The effects of mutations were interpreted based on a tertiary structural model of a subunit of the human T2. This model was constructed from the X-ray crystal structure of the homologous peroxisomal 3-ketoacyl-CoA thiolase of Saccharomyces cerevisiae. On the basis of this model, the positions of Ala333 and Ile312 were far from the active site and the mutations would be expected to destabilize the tertiary structure of T2 subunit. By contrast, Asn93 is located near the active site and may function to maintain a local loop structure. The mutation of Asn93 could directly disrupt disposition of the active site.

    Human mutation 1998;12;4;245-54

  • Enzymes of ketone body utilization in human tissues: protein and messenger RNA levels of succinyl-coenzyme A (CoA):3-ketoacid CoA transferase and mitochondrial and cytosolic acetoacetyl-CoA thiolases.

    Fukao T, Song XQ, Mitchell GA, Yamaguchi S, Sukegawa K, Orii T and Kondo N

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    We describe the distribution in human tissues of three enzymes of ketone body utilization: succinyl-CoA:3-ketoacid CoA transferase (SCOT), mitochondrial acetoacetyl-CoA thiolase (T2), and cytosolic acetoacetyl-CoA thiolase (CT). Hereditary deficiency of each of these enzymes has been associated with ketoacidosis. Physiologically the two mitochondrial enzymes have different roles: SCOT mediates energy production from ketone bodies (ketolysis), whereas T2 functions both in ketogenesis and ketolysis. In contrast, CT is implicated in cytosolic cholesterol synthesis. We investigated the tissue distribution of these enzymes in humans by quantitative immunoblots and by Northern blots. In most tissues, polypeptide and mRNA levels were proportional. CT and T2 proteins were detected in all tissues examined. CT levels were highest in liver, were 4-fold lower in adrenal glands, kidney, brain, and lung, and were lowest in skeletal and heart muscles. T2 was most abundant in liver but substantial amounts were present in kidney, heart, adrenal glands, and skeletal muscle. SCOT was detected in all tissues except liver: myocardium > brain, kidney and adrenal glands. The relative amounts of T2 and SCOT were similar in all tissues except for liver (T2 > > SCOT) and brain (SCOT > T2). The observed distribution of SCOT, T2, and CT is consistent with current views of their physiologic roles.

    Pediatric research 1997;42;4;498-502

  • Molecular basis of beta-ketothiolase deficiency: mutations and polymorphisms in the human mitochondrial acetoacetyl-coenzyme A thiolase gene.

    Fukao T, Yamaguchi S, Orii T and Hashimoto T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    beta-Ketothiolase deficiency is a deficiency in mitochondrial acetoacetyl-CoA thiolase (T2). We present here an update on mutations and polymorphisms in the human T2 gene. No large deletion or insertion has been observed in Southern blot analysis. Seventeen mutations were identified in 13 T2-deficient patients: nine missense, one nonsense, and five splice-site mutations, and two small deletions. Two polymorphic base substitutions were also detected. A common mutation in T2 deficiency has not been detected but 4 mutations (N158D, Q272X, 828 + 1, 1163 + 2) were identified in two independent families. Eleven of 25 mutant alleles identified caused aberrant splicing. In vivo expression analysis of 13 mutant cDNAs using a Lipofectin reagent suggested that T297M, A301P, A380T mutant alleles retain 5-10% normal T2 activity. A correlation between clinical phenotype and genotype in T2 deficiency seems unlikely.

    Human mutation 1995;5;2;113-20

  • Molecular, biochemical, and clinical characterization of mitochondrial acetoacetyl-coenzyme A thiolase deficiency in two further patients.

    Wakazono A, Fukao T, Yamaguchi S, Hori T, Orii T, Lambert M, Mitchell GA, Lee GW and Hashimoto T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    The molecular basis of mitochondrial acetoacetyl-CoA thiolase (T2) deficiency was studied in two patients (GK11 and GK16). Fibroblasts from each patient had detectable immunoreactive T2 polypeptide (CRM). In pulse-chase experiments, fibroblasts from GK11 had two types of CRM: one (type I CRM) disappeared after a 24-hr chase and migrated more slowly than that of the normal control; the other (type II CRM) was detected with a small amount even after a 72-hr chase and had normal electrophoretic mobility. GK16's fibroblasts had a CRM (type III) which was also detectable even after a 72-hr chase and showed a slower mobility than type I CRM. By analyzing amplified cDNA and genomic fragments, we showed that both patients are genetic compounds; GK11 for the mutations N158D and T297M, and GK16 for the mutations A301P and IVS8 (+1). Expression analyses confirmed that mutant T2 subunits with N158D, T297M, and A301P correspond to type I, II, and III CRM, respectively. Among them, only the mutant T2 polypeptide with T297M appeared to have a detectable residual activity, in spite of its instability. Cotransfection of two cDNAs containing N158D and T297M suggested that heterotetramer formation reduces residual activity in GK11 cells.

    Human mutation 1995;5;1;34-42

  • Identification of a novel exonic mutation at -13 from 5' splice site causing exon skipping in a girl with mitochondrial acetoacetyl-coenzyme A thiolase deficiency.

    Fukao T, Yamaguchi S, Wakazono A, Orii T, Hoganson G and Hashimoto T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    We identified a novel exonic mutation which causes exon skipping in the mitochondrial acetoacetyl-CoA thiolase (T2) gene from a girl with T2 deficiency (GK07). GK07 is a compound heterozygote; the maternal allele has a novel G to T transversion at position 1136 causing Gly379 to Val substitution (G379V) of the T2 precursor. In case of in vivo expression analysis, cells transfected with this mutant cDNA showed no evidence of restored T2 activity. The paternal allele was associated with exon 8 skipping at the cDNA level. At the gene level, a C to T transition causing Gln272 to termination codon (Q272STOP) was identified within exon 8, 13 bp from the 5' splice site of intron 8 in the paternal allele. The mRNA with Q272STOP could not be detected in GK07 fibroblasts, presumably because pre-mRNA with Q272STOP was unstable because of the premature termination. In vivo splicing experiments revealed that the exonic mutation caused partial skipping of exon 8. This substitution was thought to alter the secondary structure of T2 pre-mRNA around exon 8 and thus impede normal splicing. The role of exon sequences in the splicing mechanism is indicated by the exon skipping which occurred with an exonic mutation.

    The Journal of clinical investigation 1994;93;3;1035-41

  • Molecular studies of mitochondrial acetoacetyl-coenzyme A thiolase deficiency in the two original families.

    Fukao T, Yamaguchi S, Scriver CR, Dunbar G, Wakazono A, Kano M, Orii T and Hashimoto T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    We describe mutations identified in stored skin fibroblast cell lines from two original probands (JB and JM), first reported with 2-methylacetoacetic aciduria, and shown later to have a deficiency of the K(+)-activated enzyme, mitochondrial acetoacetyl-coenzyme A thiolase (T2). JB is homozygous for a 4-base insertion (GCAG) which is derived mutation. The primary mutation is an AG/gt to AG/gc transition at the 5'-splice-junction site in intron 11. An alternative splice site 4 bp downstream (Ggcag/gt) is used which causes a frame shift and replaces 39 C-terminal residues by 70 nonfunctional residues. JM is homozygous for a mutation in the translation-initiation codon (ATG to AAG). By expression analyses the JB mutation (IVS11nt2) causes an unstable T2 polypeptide and the JM mutation (M1K) severely impairs T2 mRNA translation. The JB allele associates with Dutch ancestry (no consanguinity) and the JM allele with Chilean ancestry (distant consanguinity).

    Human mutation 1993;2;3;214-20

  • Molecular basis of 3-ketothiolase deficiency: identification of an AG to AC substitution at the splice acceptor site of intron 10 causing exon 11 skipping.

    Fukao T, Yamaguchi S, Orii T, Osumi T and Hashimoto T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    3-Ketothiolase deficiency (3KTD) is the result of a deficiency in mitochondrial acetoacetyl-CoA thiolase (T2). The molecular basis of 3KTD was analyzed in a patient (GK10) and his family at the protein, cDNA and gene levels. Protein analyses showed that GK10's T2 protein was undetectable in fibroblasts even with the pulse-protein labeling method and that his parents were carriers of 3KTD. Complementary DNA analyses with PCR showed that T2 cDNA in the patient lacked the normal exon 11 sequence and that his parents were obligatory carriers of the DNA sequence which canceled exon 11. When the PCR-amplified genomic fragments around exon 11 were sequenced, an AG to AC mutation at the 3' splice site of intron 10 was detected. This mutation is presumed to be responsible for exon 11 skipping.

    Biochimica et biophysica acta 1992;1139;3;184-8

  • Identification of three mutant alleles of the gene for mitochondrial acetoacetyl-coenzyme A thiolase. A complete analysis of two generations of a family with 3-ketothiolase deficiency.

    Fukao T, Yamaguchi S, Orii T, Schutgens RB, Osumi T and Hashimoto T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    3-Ketothiolase deficiency (3KTD) stems from a deficiency of mitochondrial acetoacetyl-coenzyme A thiolase (T2). We analyzed the molecular basis of 3KTD in two generations of a family. A boy (patient 2, GK04), his father (patient 1, GK05), his mother, and his brother were studied; three mutant alleles of T2 gene were identified. Patient 1 is a compound heterozygote: one allele has a point mutation of G to A at position 547 on his T2 cDNA, causing Gly150 to Arg substitution of the mature T2 subunit, and the other allele has GT to TT transition at the 5' splice site of intron 8, causing exon 8's skipping of the T2 cDNA. Patient 2 is also a compound heterozygote: one allele inherited from his mother has AG to CG transition at the 3' splice site of intron 10, causing exon 11's skipping of the T2 cDNA, and the other allele derived from patient 1 has the G to A mutation (Gly to Arg). The brother of patient 2 is an obligatory carrier with the mutant allele causing the exon 8 skipping. This report seems to be the first complete molecular definition of 3KTD at the gene level.

    The Journal of clinical investigation 1992;89;2;474-9

  • Chromosome mapping of the human mitochondrial acetoacetyl-coenzyme A thiolase gene to 11q22.3----q23.1 by fluorescence in situ hybridization.

    Masuno M, Kano M, Fukao T, Yamaguchi S, Osumi T, Hashimoto T, Takahashi E, Hori T and Orii T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    Cytogenetics and cell genetics 1992;60;2;121-2

  • Structure and expression of the human mitochondrial acetoacetyl-CoA thiolase-encoding gene.

    Kano M, Fukao T, Yamaguchi S, Orii T, Osumi T and Hashimoto T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    To examine 3-ketothiolase deficiency at the gene level, we analyzed the structure of the human mitochondrial acetoacetyl-CoA thiolase (MAT; EC 2.3.1.9)-encoding gene (MAT). From the genomic library of a normal subject in lambda EMBL3, we isolated seven overlapping clones covering the entire length of MAT and the structural organization was determined. The gene spans approx. 27 kb and contains twelve exons interrupted by eleven introns. The 5'-flanking region of the gene lacks a conventional TATA box, but is G + C-rich and contains two CAAT boxes. Included are a putative binding site for the transcription factor, Sp1, and sequences resembling the binding sites of several other transcription factors, all features characteristic of housekeeping genes. A CAT assay revealed that a 101-bp DNA fragment immediately upstream from the cap site has promoter activity, and suggested that a DNA fragment from bp -888 to -102 probably contains a negative regulatory element(s).

    Gene 1991;109;2;285-90

  • Evidence for a structural mutation (347Ala to Thr) in a German family with 3-ketothiolase deficiency.

    Fukao T, Yamaguchi S, Tomatsu S, Orii T, Frauendienst-Egger G, Schrod L, Osumi T and Hashimoto T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    The molecular basis of 3-ketothiolase deficiency (3KTD) was examined in a 3KTD family. Immunochemical analyses showed that mitochondrial acetoacetyl-CoA thiolase (T2) biosynthesized in the patient's fibroblasts (GK06) was unstable and that the parents and brother were obligatory carriers of 3KTD. When sequencing the PCR-amplified patient's T2 cDNA, we noted a G to A replacement which caused 347Ala to Thr substitution of the mature T2 subunit. Transfection analysis revealed that this substitution resulted in an instability of the T2 protein. Analyses of the T2 cDNA and gene of the family indicated that the patient was a compound heterozygote; the allele that derived from the mother had a point mutation (347Ala to Thr) and the other allele from the father has a mutation which would abolish the T2 gene expression. This report is apparently the first definition of a mutant allele for 3KTD, at the gene level.

    Biochemical and biophysical research communications 1991;179;1;124-9

  • Molecular cloning and sequence of the complementary DNA encoding human mitochondrial acetoacetyl-coenzyme A thiolase and study of the variant enzymes in cultured fibroblasts from patients with 3-ketothiolase deficiency.

    Fukao T, Yamaguchi S, Kano M, Orii T, Fujiki Y, Osumi T and Hashimoto T

    Department of Pediatrics, Gifu University School of Medicine, Japan.

    Complementary DNAs encoding the precursor of human hepatic mitochondrial acetoacetyl-CoA thiolase (T2) (EC 2.3.1.9) were cloned and sequenced. The cDNA inserts in these clones were 1,518 bases in length when overlapped, and encoded the 427-amino acid precursor of this enzyme (45,199 mol wt). This amino acid sequence included a 33-residue leader peptide moiety and a 394-amino acid subunit of the mature enzyme (41,385 mol wt). The T2 gene expression in fibroblasts from four patients with 3-ketothiolase deficiency was analyzed by Northern blotting. The T2 mRNA in all four cell lines had the same 1.7 kb as that of the control. However, the amounts of T2 mRNA differed: the content was reduced in two cell lines (cases 1 and 3), whereas it was within a normal range in others (cases 2 and 4). Pulse labeling followed by subcellular fractionation revealed that the T2 proteins in the fibroblasts from these patients are present in the mitochondria. These results suggest that different mechanisms are involved in the enzyme defects in the four patients.

    The Journal of clinical investigation 1990;86;6;2086-92

  • 3-Ketothiolase deficiency.

    Middleton B, Bartlett K, Romanos A, Gomez Vazquez J, Conde C, Cannon RA, Lipson M, Sweetman L and Nyhan WL

    Two patients have been studied in whom the activity of the short chain-length-specific mitochondrial 3-ketothiolase was found to be deficient. Use of a range of 3-ketoacyl-CoA substrates showed that the other 3-ketothiolase isoenzymes were normal in each case. Both patients had episodic ketosis and metabolic acidosis. One patient had substantial evidence of damage to the central nervous system and two siblings who had died of the disease. The organic aciduria was characterized by the excretion of 2-methyl-3-hydroxybutyric acid and tiglyglycine. In one patient the organic aciduria was very subtle and was masked during the presence of ketosis, but it was clarified by an isoleucine load after recovery from ketosis.

    Funded by: NICHD NIH HHS: HD 04608

    European journal of pediatrics 1986;144;6;586-9

  • Beta-ketothiolase deficiency in a family confirmed by in vitro enzymatic assays in fibroblasts.

    Schutgens RB, Middleton B, vd Blij JF, Oorthuys JW, Veder HA, Vulsma T and Tegelaers WH

    European journal of pediatrics 1982;139;1;39-42

  • An inherited disorder of isoleucine catabolism causing accumulation of alpha-methylacetoacetate and alpha-methyl-beta -hydroxybutyrate, and intermittent metabolic acidosis.

    Daum RS, Scriver CR, Mamer OA, Delvin E, Lamm P and Goldman H

    Pediatric research 1973;7;3;149-60

Gene lists (9)

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
L00000010 G2C Homo sapiens Human mitochondria Human orthologues of mouse mitochondria adapted from Collins et al (2006) 91
L00000011 G2C Homo sapiens Human clathrin Human orthologues of mouse clathrin coated vesicle genes adapted from Collins et al (2006) 150
L00000012 G2C Homo sapiens Human Synaptosome Human orthologues of mouse synaptosome adapted from Collins et al (2006) 152
L00000016 G2C Homo sapiens Human PSP Human orthologues of mouse PSP adapted from Collins et al (2006) 1121
L00000049 G2C Homo sapiens TAP-PSD-95-CORE TAP-PSD-95 pull-down core list (ortho) 120
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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