G2Cdb::Gene report

Gene id
G00000041
Gene symbol
CAMK2A (HGNC)
Species
Homo sapiens
Description
calcium/calmodulin-dependent protein kinase II alpha
Orthologue
G00000016 (Mus musculus)

Databases (8)

Gene
ENSG00000070808 (Ensembl human gene)
815 (Entrez Gene)
8 (G2Cdb plasticity & disease)
CAMK2A (GeneCards)
Literature
114078 (OMIM)
Marker Symbol
HGNC:1460 (HGNC)
Protein Expression
4330 (human protein atlas)
Protein Sequence
Q9UQM7 (UniProt)

Synonyms (2)

  • CaMKIINalpha
  • KIAA0968

Literature (109)

Pubmed - other

  • Ca2+/calmodulin-dependent protein kinase II alpha is required for the initiation and maintenance of opioid-induced hyperalgesia.

    Chen Y, Yang C and Wang ZJ

    Department of Biopharmaceutical Sciences, University of Illinois, Chicago, Illinois 60612, USA.

    Repeated administration of opioids not only leads to tolerance and dependence, but also results in nociceptive enhancement called opioid-induced hyperalgesia (OIH). Nociceptive mediators involved in OIH generation remain poorly understood. In the present study, we tested the hypothesis that Ca(2+)/calmodulin-depent protein kinase II (CaMKIIalpha) is critical for OIH. Opioid-induced hyperalgesia was produced by repeated morphine administration or pellet implantation in mice. Correlating with the development of tactile allodynia and thermal hyperalgesia, spinal CaMKIIalpha activity was significantly increased in OIH. KN93, a CaMKII inhibitor, dose- and time-dependently reversed OIH and CaMKII activation without impairing locomotor coordination. To elucidate the specific CaMKII isoform involved, we targeted CaMKIIalpha by using small interfering RNA and demonstrated that knockdown of spinal CaMKIIalpha attenuated OIH. Furthermore, morphine failed to induce OIH in CaMKIIalpha(T286A) point mutant mice, although wild-type littermate mice developed robust OIH after repeated treatments with morphine. These data implicate, for the first time, an essential role of CaMKIIalpha as a cellular mechanism leading to and maintaining opioid-induced hyperalgesia.

    Funded by: NCCIH NIH HHS: AT003647, K07 AT003647, K07 AT003647-03; NHLBI NIH HHS: HL098141, R01 HL098141, R01 HL098141-01; NIDA NIH HHS: DA005050

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2010;30;1;38-46

  • Regulation of the proteasome by neuronal activity and calcium/calmodulin-dependent protein kinase II.

    Djakovic SN, Schwarz LA, Barylko B, DeMartino GN and Patrick GN

    Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093-0347, USA.

    Protein degradation via the ubiquitin proteasome system has been shown to regulate changes in synaptic strength that underlie multiple forms of synaptic plasticity. It is plausible, therefore, that the ubiquitin proteasome system is itself regulated by synaptic activity. By utilizing live-cell imaging strategies we report the rapid and dynamic regulation of the proteasome in hippocampal neurons by synaptic activity. We find that the blockade of action potentials (APs) with tetrodotoxin inhibited the activity of the proteasome, whereas the up-regulation of APs with bicuculline dramatically increased the activity of the proteasome. In addition, the regulation of the proteasome is dependent upon external calcium entry in part through N-methyl-D-aspartate receptors and L-type voltage-gated calcium channels and requires the activity of calcium/calmodulin-dependent protein kinase II (CaMKII). Using in vitro and in vivo assays we find that CaMKII stimulates proteasome activity and directly phosphorylates Rpt6, a subunit of the 19 S (PA700) subcomplex of the 26 S proteasome. Our data provide a novel mechanism whereby CaMKII may regulate the proteasome in neurons to facilitate remodeling of synaptic connections through protein degradation.

    Funded by: NIDDK NIH HHS: DK46181, R01 DK046181, R56 DK046181; NINDS NIH HHS: NS054732, R21 NS054732, R21 NS054732-01A2

    The Journal of biological chemistry 2009;284;39;26655-65

  • Case-control association study of 65 candidate genes revealed a possible association of a SNP of HTR5A to be a factor susceptible to bipolar disease in Bulgarian population.

    Yosifova A, Mushiroda T, Stoianov D, Vazharova R, Dimova I, Karachanak S, Zaharieva I, Milanova V, Madjirova N, Gerdjikov I, Tolev T, Velkova S, Kirov G, Owen MJ, O'Donovan MC, Toncheva D and Nakamura Y

    Laboratory for International Alliance, RIKEN Center for Genomic Medicine, Tsurumi-ku, Yokohama, Japan.

    Background: Bipolar affective disorder (BAD) is a psychiatric illness characterized by episodes of mania and depression. Although the etiology is not clear, epidemiological studies suggest it is a result of an interaction of genetic and environmental factors. Despite of enormous efforts and abundant studies conducted, none has yet been identified definitively a gene susceptible to bipolar disorder.

    Methods: Ninety-four Bulgarian patients diagnosed with bipolar disorder and 184 Bulgarian healthy individuals, were used for genotyping of 191 single nucleotide polymorphisms (SNPs) by TaqMan and/or Invader assays. Seventeen SNPs that revealed P value less than 0.05 in the first screening were genotyped using an additional independent set of samples, consisting of 78 BAD cases and 372 controls.

    Results: After applying the Bonferonni correction on genotyping results of 172 cases and 556 controls, only one SNP, rs1800883, in the HTR5A gene revealed a significant level of P value (P=0.000097; odds ratio=1.80 (95%CI, 1.27-2.54); corrected P=0.017).

    Conclusions: Our findings suggest that HTR5A gene could play an important role in the pathogenesis of bipolar disorder in our population. However these findings should be viewed with caution and replication studies in other populations are necessary in support of these findings.

    Funded by: Medical Research Council: G0800509

    Journal of affective disorders 2009;117;1-2;87-97

  • Pharmacogenetics of antipsychotic response in the CATIE trial: a candidate gene analysis.

    Need AC, Keefe RS, Ge D, Grossman I, Dickson S, McEvoy JP and Goldstein DB

    Center for Human Genome Variation, Institute for Genome Sciences & Policy, Duke University, Durham, NC 27708, USA.

    The Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) Phase 1 Schizophrenia trial compared the effectiveness of one typical and four atypical antipsychotic medications. Although trials such as CATIE present important opportunities for pharmacogenetics research, the very richness of the clinical data presents challenges for statistical interpretation, and in particular the risk that data mining will lead to false-positive discoveries. For this reason, it is both misleading and unhelpful to perpetuate the current practice of reporting association results for these trials one gene at a time, ignoring the fact that multiple gene-by-phenotype tests are being carried out on the same data set. On the other hand, suggestive associations in such trials may lead to new hypotheses that can be tested through both replication efforts and biological experimentation. The appropriate handling of these forms of data therefore requires dissemination of association statistics without undue emphasis on select findings. Here we attempt to illustrate this approach by presenting association statistics for 2769 polymorphisms in 118 candidate genes evaluated for 21 pharmacogenetic phenotypes. On current evidence it is impossible to know which of these associations may be real, although in total they form a valuable resource that is immediately available to the scientific community.

    Funded by: NIMH NIH HHS: N01 MH90001

    European journal of human genetics : EJHG 2009;17;7;946-57

  • Phosphorylation status of the NR2B subunit of NMDA receptor regulates its interaction with calcium/calmodulin-dependent protein kinase II.

    Raveendran R, Devi Suma Priya S, Mayadevi M, Steephan M, Santhoshkumar TR, Cheriyan J, Sanalkumar R, Pradeep KK, James J and Omkumar RV

    Rajiv Gandhi Centre for Biotechnology, Thycaud, P. O., Thiruvananthapuram-695014, Kerala, India.

    Ca(2+) influx through NMDA-type glutamate receptor at excitatory synapses causes activation of post-synaptic Ca(2+)/calmodulin-dependent protein kinase type II (CaMKII) and its translocation to the NR2B subunit of NMDA receptor. The major binding site for CaMKII on NR2B undergoes phosphorylation at Ser1303, in vivo. Even though some regulatory effects of this phosphorylation are known, the mode of dephosphorylation of NR2B-Ser1303 is still unclear. We show that phosphorylation status at Ser1303 enables NR2B to distinguish between the Ca(2+)/calmodulin activated form and the autonomously active Thr286-autophosphorylated form of CaMKII. Green fluorescent protein-alpha-CaMKII co-expressed with NR2B sequence in human embryonic kidney 293 cells was used to study intracellular binding between the two proteins. Binding in vitro was studied by glutathione-S-transferase pull-down assay. Thr286-autophosphorylated alpha-CaMKII or the autophosphorylation mimicking mutant, T286D-alpha-CaMKII, binds NR2B sequence independent of Ca(2+)/calmodulin unlike native wild-type alpha-CaMKII. We show enhancement of this binding by Ca(2+)/calmodulin. Phosphorylation or a phosphorylation mimicking mutation on NR2B (NR2B-S1303D) abolishes the Ca(2+)/calmodulin-independent binding whereas it allows the Ca(2+)/calmodulin-dependent binding of alpha-CaMKII in vitro. Similarly, the autonomously active mutants, T286D-alpha-CaMKII and F293E/N294D-alpha-CaMKII, exhibited Ca(2+)-independent binding to non-phosphorylatable mutant of NR2B under intracellular conditions. We also show for the first time that phosphatases in the brain such as protein phosphatase 1 and protein phosphatase 2A dephosphorylate phospho-Ser1303 on NR2B.

    Journal of neurochemistry 2009;110;1;92-105

  • Tumor necrosis factor-alpha enhances neutrophil adhesiveness: induction of vascular cell adhesion molecule-1 via activation of Akt and CaM kinase II and modifications of histone acetyltransferase and histone deacetylase 4 in human tracheal smooth muscle cells.

    Lee CW, Lin CC, Luo SF, Lee HC, Lee IT, Aird WC, Hwang TL and Yang CM

    Department of Physiology and Pharmacology, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-San, Tao-Yuan, Taiwan.

    Up-regulation of vascular cell adhesion molecule-1 (VCAM-1) involves adhesions between both circulating and resident leukocytes and the human tracheal smooth muscle cells (HTSMCs) during airway inflammatory reaction. We have demonstrated previously that tumor necrosis factor (TNF)-alpha-induced VCAM-1 expression is regulated by mitogen-activated protein kinases, nuclear factor-kappaB, and p300 activation in HTSMCs. In addition to this pathway, phosphorylation of Akt and CaM kinase II has been implicated in histone acetyltransferase and histone deacetylase 4 (HDAC4) activation. Here, we investigated whether these different mechanisms participated in TNF-alpha-induced VCAM-1 expression and enhanced neutrophil adhesion. TNF-alpha significantly increased HTSMC-neutrophil adhesions, and this effect was associated with increased expression of VCAM-1 on the HTSMCs and was blocked by the selective inhibitors of Src [4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]-pyrimidine (PP1)], epidermal growth factor receptor [EGFR; 4-(3'-chloroanilino)-6,7-dimethoxy-quinazoline, (AG1478)], phosphatidylinositol 3-kinase (PI3K) [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride(LY294002) and wortmannin],calcium[1,2-bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester; BAPTA-AM], phosphatidylinositol-phospholipase C (PLC) [1-[6-[[17beta-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U73122)], protein kinase C (PKC) [12-(2-cyanoethyl)-6,7,12, 13-tetrahydro-13-methyl-5-oxo-5H-indolo(2,3-a)pyrrolo(3,4-c)-carbazole (Gö6976), rottlerin, and 3-1-[3-(amidinothio)propyl-1H-indol-3-yl]-3-(1-methyl-1H-indol-3-yl) maleimide (bisindolylmaleimide IX) (Ro 31-8220)], CaM (calmidazolium chloride), CaM kinase II [(8R(*),9S(*),11S(*))-(-)-9-hydroxy-9-methoxycarbonyl-8-methyl-14-n-propoxy-2,3,9, 10-tetrahydro-8,11-epoxy, 1H,8H, 11H-2,7b,11a-triazadibenzo[a,g]cycloocta[cde]trinden-1-one (KT5926) and 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-l-tyrosyl]-4-phenylpiperazine (KN62)], p300 (curcumin), and HDAC (trichostatin A) or transfection with short interfering RNAs for Src, Akt, PKCalpha, PKCmu, and HDAC4. At gene regulation level, reverse-transcriptase polymerase chain reaction and promoter assays revealed that expression of VCAM-1 was also attenuated by these signaling molecule inhibitors. Moreover, TNF-alpha induced Akt and CaM kinase II phosphorylation via cascades through Src/EGFR/PI3K and PLC/calcium/CaM, respectively. Finally, activation of Akt and CaM kinase II may eventually lead to the acetylation of histone residues and phosphorylation of histone deacetylase. These findings revealed that TNF-alpha induced VCAM-1 expression via multiple signaling pathways. Blockade of these pathways may be selectively targeted to reduce neutrophil adhesion via VCAM-1 suppression and attenuation of the inflammatory responses in airway diseases.

    Molecular pharmacology 2008;73;5;1454-64

  • A novel endogenous human CaMKII inhibitory protein suppresses tumor growth by inducing cell cycle arrest via p27 stabilization.

    Wang C, Li N, Liu X, Zheng Y and Cao X

    Institute of Immunology and National Key Laboratory of Medical Immunology, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, China.

    Calcium/calmodulin-dependent protein kinase II (CaMKII) regulates numerous physiological functions. Inhibition of CaMKII activity, mostly by synthetic reagents, has been proved to suppress cell growth in many cases. So far there are no reports about the physiological functions and underlying mechanisms of endogenous CaMKII inhibitory proteins in cell cycle progression. Here we report the characterization of a novel human endogenous CaMKII inhibitor, human CaMKII inhibitory protein alpha (hCaMKIINalpha), which directly interacts with activated CaMKII and effectively inhibits CaMKII activity. hCaMKIINalpha expression is negatively correlated with the severity of human colon adenocarcinoma. Overexpression of hCaMKIINalpha inhibits colon adenocarcinoma growth in vitro and in vivo by arresting the cell cycle at the S phase through its conserved inhibitory region (27CIR), whereas silencing the hCaMKIINalpha expression accelerates tumor growth and cell cycle progression. We found that the effect of hCaMKIINalpha on cell cycle is correlated with up-regulation of p27 expression, which may be due to the inhibition of proteasome degradation, but not transcriptional regulation, of p27. Moreover, hCaMKIINalpha deactivated MEK/ERK, which is prerequisite to the inhibition of Thr-187 phosphorylation and subsequent proteasomal degradation of p27, causing the inhibition of S-phase progression of cell cycle. The findings underscore a link between hCaMKIINalpha-mediated inhibition of CaMKII activity and p27-dependent pathways in controlling tumor cell growth and cell cycle and imply a potential application of hCaMKIINalpha in the therapeutics of colon cancers.

    The Journal of biological chemistry 2008;283;17;11565-74

  • Motor protein-dependent transport of AMPA receptors into spines during long-term potentiation.

    Correia SS, Bassani S, Brown TC, Lisé MF, Backos DS, El-Husseini A, Passafaro M and Esteban JA

    Department of Pharmacology, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, Michigan 48109-0632, USA.

    The regulated trafficking of neurotransmitter receptors at synapses is critical for synaptic function and plasticity. However, the molecular machinery that controls active transport of receptors into synapses is largely unknown. We found that, in rat hippocampus, the insertion of AMPA receptors (AMPARs) into spines during synaptic plasticity requires a specific motor protein, which we identified as myosin Va. We found that myosin Va associates with AMPARs through its cargo binding domain. This interaction was enhanced by active, GTP-bound Rab11, which is also transported by the motor protein. Myosin Va mediated the CaMKII-triggered translocation of GluR1 receptors from the dendritic shaft into spines, but it was not required for constitutive GluR2 trafficking. Accordingly, myosin Va was specifically required for long-term potentiation, but not for basal synaptic transmission. In summary, we identified the specific motor protein and organelle acceptor that catalyze the directional transport of AMPARs into spines during activity-dependent synaptic plasticity.

    Funded by: NIMH NIH HHS: F31-MH070205, MH070417; Telethon: TCR07006

    Nature neuroscience 2008;11;4;457-66

  • Ca2+/calmodulin-dependent protein kinase IIdelta and protein kinase D overexpression reinforce the histone deacetylase 5 redistribution in heart failure.

    Bossuyt J, Helmstadter K, Wu X, Clements-Jewery H, Haworth RS, Avkiran M, Martin JL, Pogwizd SM and Bers DM

    Department of Physiology, Loyola University Chicago, Maywood, IL 60153, USA.

    Cardiac hypertrophy and heart failure (HF) are associated with reactivation of fetal cardiac genes, and class II histone deacetylases (HDACs) (eg, HDAC5) have been strongly implicated in this process. We have shown previously that inositol trisphosphate, Ca2+/calmodulin-dependent protein kinase II (CaMKII), and protein kinase (PK)D are involved in HDAC5 phosphorylation and nuclear export in normal adult ventricular myocytes and also that CaMKIIdelta and inositol trisphosphate receptors are upregulated in HF. Here we tested whether, in our rabbit HF model, nucleocytoplasmic shuttling of HDAC5 was altered either at baseline or in response to endothelin-1, which would indicate HDAC5 phosphorylation and transcription effects. The fusion protein HDAC5-green fluorescent protein (HDAC5-GFP) was more cytosolic in HF myocytes (F(nuc)/F(cyto) 3.3+/-0.3 vs 7.2+/-0.4 in control), and HDAC5 was more phosphorylated. Despite this baseline cytosolic HDAC5 shift, endothelin-1 produced more rapid HDAC5-GFP nuclear export in HF versus control myocytes. We also find that PKD and CaMKIIdelta(C) expression and activation state are increased in both rabbit and human HF. Inhibition of either CaMKII or PKD in HF myocytes partially restored the HDAC5-GFP F(nuc)/F(cyto) toward control, and simultaneous inhibition restored F(nuc)/F(cyto) to that in control myocytes. Moreover, adenovirus-mediated overexpression of PKD, CaMKIIdelta(B), or CaMKIIdelta(C) reduced baseline HDAC5 F(nuc)/F(cyto) in control myocytes (3.4+/-0.5, 3.8+/-0.5, and 5.2+/-0.5, respectively), approaching that seen in HF. We conclude that chronic upregulation and activation of inositol trisphosphate receptors, CaMKII, and PKD in HF shifts HDAC5 out of the nucleus, derepressing transcription of hypertrophic genes. This may directly contribute to the development and/or maintenance of HF.

    Funded by: NHLBI NIH HHS: P01-HL80101, R01 HL064724, R01-HL46929, R01-HL64724

    Circulation research 2008;102;6;695-702

  • Identification of the RA response element and transcriptional silencer in human alphaCaMKII promoter.

    Wang L, Bai J and Hu Y

    Key Lab of Brain Functional Genomics, MOE and STCSM, Shanghai Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road North, Shanghai, 200062, China.

    The promoter of alpha subunit of the rat calcium/calmodulin-dependent protein kinase II (alphaCaMKII) gene was identified to contain an essential TATA element. Cell-based functional assay showed that the rat promoter displayed greater activity in neuronal cells than in non-neuronal cells. To characterize the human alphaCaMKII promoter, we have developed a promoter-reporter gene assay using different cell lines. A 2047 base pairs (bp) human alphaCaMKII gene promoter was cloned from human genomic DNA. Unlike the rat alphaCaMKII promoter, DNA sequence analysis showed that the human promoter was devoid of TATA element. We made series deletions of the promoter and fused the different sizes of the human promoter sequences to a luciferase reporter gene. The promoter-reporter constructs were transfected into human neuroblastoma SH-SY5Y, human neuroblastoma BE(2)-M17, and rat pheochromocytoma PC12 neuronal cell lines as well as human embryonic kidney HEK293 and human glioma U251 non-neuronal cell lines. The reporter gene assay demonstrated that the human alphaCaMKII promoter displayed high activity in the neuronal cell lines, while the activity was low in non-neuronal cell lines. All-trans retinoic acid (RA) enhanced the promoter activity in SH-SY5Y cells. Further analysis showed that there were two RA response elements located between +11 and +136 and -1911 to -593. In addition, we have identified a potent silencer at position -179 to -244 of the human alphaCaMKII promoter.

    Molecular biology reports 2008;35;1;37-44

  • Amphetamine sensitization elevates CaMKIIbeta mRNA.

    Greenstein R, Novak G and Seeman P

    Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada M5S 1A8.

    Recent studies have shown that the elevation in calcium/calmodulin-dependent protein kinase II (CaMKII) may play an important role in amphetamine-induced dopamine release, as well as in the increase of dopamine D2 receptor high-affinitystates in psychosis. Because amphetamine sensitization is a widely used animal model of psychosis or schizophrenia, we investigated whether amphetamine sensitization results in an overall increase in the alpha and beta subunits of CaMKII. To answer this question, we measured CaMKII alpha and beta subunit mRNA expression using Real-Time Quantitative PCR in amphetamine-sensitized rat striata, compared to saline-treated controls. The results were then standardized to beta-glucuronidase, a housekeeping gene. Our results showed a statistically significant increase in the CaMKII beta subunit, and an increase in the alpha subunit which did not reach statistical significance. Because the levels of both CaMKIIbeta and CaMKIIalpha play a role in neuronal function and synapse formation, the present finding of an elevated level of CaMKII beta and alpha subunit mRNA in the amphetamine-sensitized model of psychosis points to the possibility of dysregulated levels of CaMKII subunits in human psychosis.

    Synapse (New York, N.Y.) 2007;61;10;827-34

  • Effect of endurance exercise training on Ca2+ calmodulin-dependent protein kinase II expression and signalling in skeletal muscle of humans.

    Rose AJ, Frøsig C, Kiens B, Wojtaszewski JF and Richter EA

    Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Universitetsparken 13, Copenhagen, Denmark 2100. arose@ifi.ku.dk

    Here the hypothesis that skeletal muscle Ca(2+)-calmodulin-dependent kinase II (CaMKII) expression and signalling would be modified by endurance training was tested. Eight healthy, young men completed 3 weeks of one-legged endurance exercise training with muscle samples taken from both legs before training and 15 h after the last exercise bout. Along with an approximately 40% increase in mitochondrial F(1)-ATP synthase expression, there was an approximately 1-fold increase in maximal CaMKII activity and CaMKII kinase isoform expression after training in the active leg only. Autonomous CaMKII activity and CaMKII autophosphorylation were increased to a similar extent. However, there was no change in alpha-CaMKII anchoring protein expression with training. Nor was there any change in expression or Thr(17) phosphorylation of the CaMKII substrate phospholamban with training. However, another CaMKII substrate, serum response factor (SRF), had an approximately 60% higher phosphorylation at Ser(103) after training, with no change in SRF expression. There were positive correlations between the increases in CaMKII expression and SRF phosphorylation as well as F(1)ATPase expression with training. After training, there was an increase in cyclic-AMP response element binding protein phosphorylation at Ser(133), but not expression, in muscle of both legs. Taken together, skeletal muscle CaMKII kinase isoform expression and SRF phosphorylation is higher with endurance-type exercise training, adaptations that are restricted to active muscle. This may contribute to greater Ca(2+) mediated regulation during exercise and the altered muscle phenotype with training.

    The Journal of physiology 2007;583;Pt 2;785-95

  • alpha-CaMKII controls the growth of human osteosarcoma by regulating cell cycle progression.

    Yuan K, Chung LW, Siegal GP and Zayzafoon M

    Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.

    Osteosarcoma is the most frequent type of primary bone cancer in children and adolescents. These malignant osteoid forming tumors are characterized by their uncontrolled hyperproliferation. Here, we investigate the role of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) in the growth of human osteosarcoma. We show that alpha-CaMKII is expressed in human osteosarcoma cell lines and in primary osteosarcoma tissue derived from patients. The pharmacologic inhibition of CaMKII in MG-63 and 143B human osteosarcoma cells by KN-93 resulted in an 80 and 70% decrease in proliferation, respectively, and induced cell cycle arrest in the G(0)/G(1) phase. The in vivo administration of KN-93 to mice xenografted with human osteosarcoma cells significantly decreased intratibial and subcutaneous tumor growth. Mechanistically, KN-93 and alpha-CaMKII siRNA increased p21((CIP/KIP)) gene expression, protein levels, and decreased the phosphorylation of retinoblastoma protein and E2F transactivation. Furthermore, the inhibition of CaMKII decreased membrane-bound Tiam1 and GTP-bound Rac1, which are known to be involved in p21 expression and tumor growth in a variety of solid malignant neoplasms. Our results suggest that CaMKII plays a critical role in the growth of osteosarcoma, and its inhibition could be an attractive therapeutic target to combat conventional high-grade osteosarcoma in children.

    Funded by: NCI NIH HHS: CA093796, CA098543, P01 CA098912, P01-CA098912, R01 CA093796, U10 CA098543; NIAMS NIH HHS: P30 AR046031, P30 AR046031-070001, P30-AR46031; NIDDK NIH HHS: P30 DK056336, P30-DK56336

    Laboratory investigation; a journal of technical methods and pathology 2007;87;9;938-50

  • Bcl10 is phosphorylated on Ser138 by Ca2+/calmodulin-dependent protein kinase II.

    Ishiguro K, Ando T, Goto H and Xavier R

    Molecular Biology and Pathogenesis of Gastroenterology, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi 466-8550, Japan. kio@med.nagoya-u.ac.jp

    Ordered assembly of scaffold proteins Carma1-Bcl10-Malt1 determines NF-kappaB activation following T cell receptor (TCR) engagement. Carma1-Bcl10 interaction and the signaling pathway are controlled by Carma1 phosphorylation, which are induced by PKCtheta and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). In addition to Carma1 phosphorylation, previous studies have demonstrated that Bcl10 is phosphorylated in the C-terminal Ser/Thr rich region following TCR engagement. However the kinases that phosphorylate Bcl10 are incompletely understood. Here we show that CaMKII phosphorylates Bcl10 on Ser138. Furthermore, a CaMKII inhibitor, KN93, and CaMKII siRNA substantially reduce Bcl10 phosphorylation induced by phorbol myristate acetate/ionomycin. S138A mutation prolongs Bcl10-induced NF-kappaB activation, suggesting that Bcl10 phosphorylation is involved in attenuation of NF-kappaB activation. These findings suggest that CaMKII modulates NF-kappaB activation via phosphorylating Bcl10 as well as Carma1.

    Funded by: NIDDK NIH HHS: P30 DK040561, P30 DK040561-11

    Molecular immunology 2007;44;8;2095-100

  • 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

  • Calmodulin kinase II is involved in voltage-dependent facilitation of the L-type Cav1.2 calcium channel: Identification of the phosphorylation sites.

    Lee TS, Karl R, Moosmang S, Lenhardt P, Klugbauer N, Hofmann F, Kleppisch T and Welling A

    Institut für Pharmakologie und Toxikologie, Technische Universität München, München, Germany.

    Calcium-dependent facilitation of L-type calcium channels has been reported to depend on the function of calmodulin kinase II. In contrast, the mechanism for voltage-dependent facilitation is not clear. In HEK 293 cells expressing Ca(v)1.2, Ca(v)beta2a, and calmodulin kinase II, the calcium current measured at +30 mV was facilitated up to 1.5-fold by a 200-ms-long prepulse to +160 mV. This voltage-dependent facilitation was prevented by the calmodulin kinase II inhibitors KN93 and the autocamtide-2-related peptide. In cells expressing the Ca(v)1.2 mutation I1649E, a residue critical for the binding of Ca2+-bound calmodulin, facilitation was also abolished. Calmodulin kinase II was coimmunoprecipitated with the Ca(v)1.2 channel from murine heart and HEK 293 cells expressing Ca(v)1.2 and calmodulinkinase II. The precipitated Ca(v)1.2 channel was phosphorylated in the presence of calmodulin and Ca2+. Fifteen putative calmodulin kinase II phosphorylation sites were identified mostly in the carboxyl-terminal tail of Ca(v)1.2. Neither truncation at amino acid 1728 nor changing the II-III loop serines 808 and 888 to alanines affected facilitation of the calcium current. In contrast, facilitation was decreased by the single mutations S1512A and S1570A and abolished by the double mutation S1512A/S1570A. These serines flank the carboxyl-terminal EF-hand motif. Immunoprecipitation of calmodulin kinase II with the Ca(v)1.2 channel was not affected by the mutation S1512A/S1570A. The phosphorylation of the Ca(v)1.2 protein was strongly decreased in the S1512A/S1570A double mutant. These results suggest that voltage-dependent facilitation of the Ca(v)1.2 channel depends on the phosphorylation of Ser1512/Ser1570 by calmodulin kinase II.

    The Journal of biological chemistry 2006;281;35;25560-7

  • Regulation of protein phosphatase 2A-mediated recruitment of IQGAP1 to beta1 integrin by EGF through activation of Ca2+/calmodulin-dependent protein kinase II.

    Takahashi K and Suzuki K

    Molecular Cell Biology Division, Kanagawa Cancer Center Research Institute, Yokohama, Japan. ktaka@gancen.asahi.yokohama.jp

    Maintenance of beta1 integrin-mediated cell adhesion in quiescent human mammary epithelial (HME) cells requires protein phosphatase (PP) 2A for not only dephosphorylation of beta1 integrin but also recruitment of IQGAP1 to Rac-bound beta1 integrin. However, how PP2A-dependent regulatory machinery of cell adhesion responds to EGF remains to be elucidated. We report here that phosphorylated Ca2+/calmodulin-dependent protein kinase II (CaMKII) at threonine 286 was involved in the beta1 integrin complex that consisted of PP2A, Rac, and IQGAP1 in quiescent HME cells. Stimulation of the cells with EGF concomitantly induced an increase in intracellular Ca2+, activation of CaMKII, and dissociation of PP2A-IQGAP1-CaMKII from beta1 integrin-Rac. Because the activation of CaMKII and dissociation of PP2A-IQGAP1-CaMKII were blocked by either Ca2+-chelator or CaMKII inhibitor, we therefore propose that EGF has the ability to abrogate the PP2A function in the maintenance of beta1 integrin-mediated cell adhesion by dissociation of PP2A-IQGAP1-CaMKII from beta1 integrin-Rac through activation of CaMKII.

    Journal of cellular physiology 2006;208;1;213-9

  • Hyaluronan-CD44 interaction with leukemia-associated RhoGEF and epidermal growth factor receptor promotes Rho/Ras co-activation, phospholipase C epsilon-Ca2+ signaling, and cytoskeleton modification in head and neck squamous cell carcinoma cells.

    Bourguignon LY, Gilad E, Brightman A, Diedrich F and Singleton P

    Department of Medicine, University of California at San Francisco and Endocrine Unit (111N), Veterans Affairs Medical Center, San Francisco, California 94121, USA. lillyb@itsa.ucsf.edu

    In this study we have examined the interaction of CD44 (a major hyaluronan (HA) receptor) with a RhoA-specific guanine nucleotide exchange factor (leukemia-associated RhoGEF (LARG)) in human head and neck squamous carcinoma cells (HNSCC-HSC-3 cell line). Immunoprecipitation and immunoblot analyses indicate that CD44 and the LARG protein are expressed in HSC-3 cells and that these two proteins are physically associated as a complex. HA-CD44 binding induces LARG-specific RhoA signaling and phospholipase C epsilon (PLC epsilon) activity. In particular, the activation of RhoA-PLC epsilon by HA stimulates inositol 1,4,5-triphosphate production, intracellular Ca2+ mobilization, and the up-regulation of Ca2+/calmodulin-dependent kinase II (CaMKII), leading to phosphorylation of the cytoskeletal protein, filamin. The phosphorylation of filamin reduces its interaction with filamentous actin, promoting tumor cell migration. The CD44-LARG complex also interacts with the EGF receptor (EGFR). Most importantly, the binding of HA to the CD44-LARG-EGFR complex activates the EGFR receptor kinase, which in turn promotes Ras-mediated stimulation of a downstream kinase cascade including the Raf-1 and ERK pathways leading to HNSCC cell growth. Using a recombinant fragment of LARG (the LARG-PDZ domain) and a binding assay, we have determined that the LARG-PDZ domain serves as a direct linker between CD44 and EGFR. Transfection of the HSC-3 cells with LARG-PDZcDNA significantly reduces LARG association with CD44 and EGFR. Overexpression of the LARG-PDZ domain also functions as a dominant-negative mutant (similar to the PLC/Ca2+-calmodulin-dependent kinase II (CaMKII) and EGFR/MAPK inhibitor effects) to block HA/CD44-mediated signaling events (e.g. EGFR kinase activation, Ras/RhoA co-activation, Raf-ERK signaling, PLC epsilon-mediated inositol 1,4,5-triphosphate production, intracellular Ca2+ mobilization, CaMKII activity, filamin phosphorylation, and filamin-actin binding) and to abrogate tumor cell growth/migration. Taken together, our findings suggest that CD44 interaction with LARG and EGFR plays a pivotal role in Rho/Ras co-activation, PLC epsilon-Ca2+ signaling, and Raf/ERK up-regulation required for CaMKII-mediated cytoskeleton function and in head and neck squamous cell carcinoma progression.

    Funded by: NCI NIH HHS: R01 CA66163, R01 CA78633; NIAMS NIH HHS: P01 AR39448

    The Journal of biological chemistry 2006;281;20;14026-40

  • Transition from reversible to persistent binding of CaMKII to postsynaptic sites and NR2B.

    Bayer KU, LeBel E, McDonald GL, O'Leary H, Schulman H and De Koninck P

    Department of Pharmacology, Program in Neuroscience, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA. ulli.bayer@uchsc.edu

    Changes in protein-protein interactions and activity states have been proposed to underlie persistent synaptic remodeling that is induced by transient stimuli. Here, we show an unusual stimulus-dependent transition from a short-lived to long-lasting binding between a synaptic receptor and its transducer. Both molecules, the NMDA receptor subunit NR2B and Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII), are strongly implicated in mediating synaptic plasticity. We show that CaMKII reversibly translocates to synaptic sites in response to brief stimuli, but its resident time at the synapse increases after longer stimulation. Thus, CaMKII localization reflects temporal patterns of synaptic stimulation. We have identified two surface regions of CaMKII involved in short-lived and long-term interactions with NR2B. Our results support an initial reversible and Ca2+/CaM-dependent binding at the substrate-binding site ("S-site"). On longer stimulation, a persistent interaction is formed at the T286-binding site ("T-site"), thereby keeping the autoregulatory domain displaced and enabling Ca2+/CaM-independent kinase activity. Such dual modes of interaction were observed in vitro and in HEK cells. In hippocampal neurons, short-term stimulation initiates a reversible translocation, but an active history of stimulation beyond some threshold produces a persistent synaptic localization of CaMKII. This activity-dependent incorporation of CaMKII into postsynaptic sites may play a role in maturation and plasticity of synapses.

    Funded by: NINDS NIH HHS: R01 NS052644, R01 NS052644-01A2

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2006;26;4;1164-74

  • Increased expression of calcium/calmodulin-dependent protein kinase IIbeta in frontal cortex in schizophrenia and depression.

    Novak G, Seeman P and Tallerico T

    Department of Pharmacology, Medical Sciences Building Room 4344, University of Toronto, Ontario, Canada.

    In searching for genes dysregulated in schizophrenia, we measured the expression of the two splice variants of calcium/calmodulin-dependent protein kinase II (CaMKIIalpha and CaMKIIbeta) in postmortem frontal cerebral cortex tissues from patients who had died with schizophrenia, bipolar disorder, or severe depression. The mRNA levels of expression of these two splice variants were measured by real-time Quantitative PCR, using an Mx4000 instrument. The values for the expression of CaMKIIalpha and CaMKIIbeta were normalized by the expression of beta-glucuronidase in the tissues. The expression of CaMKIIalpha was significantly elevated in the depression tissues by 29%. The expression of CaMKIIbeta was significantly elevated in the schizophrenia tissues by 27%, and in the depression tissues by 36%. Because CaMKIIbeta influences the expression of many neuroreceptors and influences neural outgrowth and pruning, its altered expression in the cerebral cortex in schizophrenia or depression may contribute to these diseases.

    Funded by: NIDA NIH HHS: 5 R01DA07223-12

    Synapse (New York, N.Y.) 2006;59;1;61-8

  • Multivalent interactions of calcium/calmodulin-dependent protein kinase II with the postsynaptic density proteins NR2B, densin-180, and alpha-actinin-2.

    Robison AJ, Bass MA, Jiao Y, MacMillan LB, Carmody LC, Bartlett RK and Colbran RJ

    Department of Molecular Physiology and Biophysics, Center for Molecular Neuroscience, Vanderbilt-Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37232-0615, USA.

    Dendritic calcium/calmodulin-dependent protein kinase II (CaMKII) is dynamically targeted to the synapse. We show that CaMKIIalpha is associated with the CaMKII-binding proteins densin-180, the N-methyl-D-aspartate receptor NR2B subunit, and alpha-actinin in postsynaptic density-enriched rat brain fractions. Residues 819-894 within the C-terminal domain of alpha-actinin-2 constitute the minimal CaMKII-binding domain. Similar amounts of Thr286-autophosphorylated CaMKIIalpha holoenzyme [P-T286]CaMKII bind to alpha-actinin-2 as bind to NR2B (residues 1260-1339) or to densin-180 (residues 1247-1495) in glutathione-agarose cosedimentation assays, even though the CaMKII-binding domains share no amino acid sequence similarity. Like NR2B, alpha-actinin-2 binds to representative splice variants of each CaMKII gene (alpha, beta, gamma, and delta), whereas densin-180 binds selectively to CaMKIIalpha. In addition, C-terminal truncated CaMKIIalpha monomers can interact with NR2B and alpha-actinin-2, but not with densin-180. Soluble alpha-actinin-2 does not compete for [P-T286]CaMKII binding to immobilized densin-180 or NR2B. However, soluble densin-180, but not soluble NR2B, increases CaMKII binding to immobilized alpha-actinin-2 by approximately 10-fold in a PDZ domain-dependent manner. A His6-tagged NR2B fragment associates with GST-densin or GST-actinin but only in the presence of [P-T286]CaMKII. Similarly, His6-tagged densin-180 or alpha-actinin fragments associate with GST-NR2B in a [P-T286]CaMKII-dependent manner. In addition, GST-NR2B and His6-tagged alpha-actinin can bind simultaneously to monomeric CaMKII subunits. In combination, these data support a model in which [P-T286]CaMKIIalpha can simultaneously interact with multiple dendritic spine proteins, possibly stabilizing the synaptic localization of CaMKII and/or nucleating a multiprotein synaptic signaling complex.

    Funded by: NIDDK NIH HHS: 5T32-DK07563; NIMH NIH HHS: F32-MH068129, R01 MH063232, R01 MH063232-05, R01-MH63232; NINDS NIH HHS: R01-NS44282

    The Journal of biological chemistry 2005;280;42;35329-36

  • Activation of nuclear factor {kappa}B by somatostatin type 2 receptor in pancreatic acinar AR42J cells involves G{alpha}14 and multiple signaling components: a mechanism requiring protein kinase C, calmodulin-dependent kinase II, ERK, and c-Src.

    Liu AM 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.

    Medications targeting the somatostatin type 2 receptor (SSTR2) have been employed for pancreatic inflammations and cancers, possibly via the regulation of the transcription factor nuclear factor kappaB (NFkappaB). Here we demonstrate that in tumoral pancreatic acinar AR42J cells, activation of SSTR2 leads to stimulation of the inhibitor kappaB kinase (IKK)/NFkappaB signaling cascade via pertussis toxin-insensitive G proteins in a time- and dose-dependent manner. The inability of G(q/11) and G(12/13) proteins to activate IKK/NFkappaB by SSTR2 in transfected human embryonic kidney 293 cells and the lack of Galpha(16) in AR42J cells suggested a possible role of Galpha(14) in mediating SSTR2-induced responses. This regulatory role of Galpha(14) was further confirmed by the activation of IKK and NFkappaB in human embryonic kidney 293 cells expressing SSTR2 and Galpha(14) upon induction. The stimulatory effect of Gbeta(1)gamma(2) and the abrogation by overexpressing transducin confirmed the participation of Gbetagamma in SSTR2-mediated IKK/NFkappaB activation. By the application of specific inhibitors and dominant negative mutants, phospholipase Cbeta, protein kinase C, and calmodulin-dependent kinase II were shown to be involved in SSTR2-induced responses. Inhibition of c-Src and numerous intermediates, including Ras, Raf-1 kinase, MEK1/2, along with the extracellular signal-regulated kinase cascade attenuated somatostatin-mediated IKK/NFkappaB activation. Although c-Jun N-terminal kinase and p38 mitogen-activated protein kinase (MAPK) were also stimulated by SSTR2, suppression of these two MAPKs was ineffective in altering the somatostatin-mediated responses. Similar results were also obtained using AR42J cells. These data suggest that activation of the IKK/NFkappaB signaling cascade by SSTR2 requires a complicated network consisting of Galpha(14) and multiple intermediates.

    The Journal of biological chemistry 2005;280;41;34617-25

  • CaMKIIalpha enhances the desensitization of NR2B-containing NMDA receptors by an autophosphorylation-dependent mechanism.

    Sessoms-Sikes S, Honse Y, Lovinger DM and Colbran RJ

    Department of Molecular Physiology and Biophysics, The Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.

    Long-term potentiation or depression of synaptic function often requires Ca2+ influx via NMDA-type glutamate receptors (NMDARs) and changes in the autophosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) at Thr286. Autophosphorylated CaMKII binds directly to NMDAR subunits, co-localizes with NMDARs in the postsynaptic density, and phosphorylates NR2B subunits at Ser1303. Here, we demonstrate that CaMKIIalpha enhances the extent and/or rate of desensitization of NMDA-induced macroscopic currents in HEK293 cells co-expressing NR2B with either the NR1(011) or NR1(101) splice variants, without significantly changing other current parameters. In contrast, the extent of desensitization of NMDARs containing NR2A in place of NR2B is significantly decreased by co-expression of CaMKIIalpha. Kinases harboring K42R (inactive kinase) or T286A (autophosphorylation-deficient) mutations are defective in enhancing the desensitization of NR1/NR2B channels. In addition, the CaMKII-dependent enhancement of NR1/NR2B channel desensitization is abrogated by intracellular loading with BAPTA. These data suggest a novel mechanism for Ca2+-dependent negative-feedback regulation of NR2B-containing NMDARs in a CaMKII activity- and autophosphorylation-dependent manner that may modulate NMDAR-mediated synaptic plasticity.

    Funded by: Intramural NIH HHS; NIMH NIH HHS: R01-MH63232

    Molecular and cellular neurosciences 2005;29;1;139-47

  • The expression of calcium/calmodulin-dependent protein kinase II-alpha in the hippocampus of patients with Alzheimer's disease and its links with AD-related pathology.

    Wang YJ, Chen GH, Hu XY, Lu YP, Zhou JN and Liu RY

    Geriatric Department, the First Affiliated Hospital, Anhui Medical University, Hefei 230022, P.R. China.

    Alzheimer's disease (AD) is characterized pathologically by selective neuronal loss and by the formation of neurofibrillary tangles (NFTs) and senile plaques (SPs). Since calcium/calmodulin-dependent protein kinase II-alpha (CaMKII-alpha), one of the most abundant kinases in the brain, is involved in the phosphorylation of tau and amyloid precursor protein (APP), we examined the expression of CaMKII-alpha and its relationships with the neuropathology in the hippocampus of AD patients using immunohistochemistry and double-labeling immunofluorescence methods. The results showed that CaMKII-alpha containing neurons were selectively lost in the CA1 subfield of AD hippocampus and accompanied with enhanced immunoreactivity in the remaining neurons. About 33% hyperphosphorylated tau-containing neurons labeled by monoclonal antibody AT-8 were also immunoreactive for CaMKII-alpha. Moreover, we found for the first time that the immunoreactivity of CaMKII-alpha was largely deposited in the SPs of the AD hippocampus. The pattern of the co-localization of CaMKII-alpha with beta amyloid depended on the type of SPs. Since the co-localization of CaMKII-alpha with hyperphosphorylated tau is relatively rare, we concluded that CaMKII-alpha may be related with beta-amyloid more closely than being involved in tau hyperphosphorylation.

    Brain research 2005;1031;1;101-8

  • A novel scaffold protein, TANC, possibly a rat homolog of Drosophila rolling pebbles (rols), forms a multiprotein complex with various postsynaptic density proteins.

    Suzuki T, Li W, Zhang JP, Tian QB, Sakagami H, Usuda N, Usada N, Kondo H, Fujii T and Endo S

    Department of Neuroplasticity, Institute on Ageing and Adaptation, Shinshu University Graduate School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan. suzukit@sch.md.shinshu-u.ac.jp

    We cloned from the rat brain a novel gene, tanc (GenBank Accession No. AB098072), which encoded a protein containing three tetratricopeptide repeats (TPRs), ten ankyrin repeats and a coiled-coil region, and is possibly a rat homolog of Drosophila rolling pebbles (rols). The tanc gene was expressed widely in the adult rat brain. Subcellular distribution, immunohistochemical study of the brain and immunocytochemical studies of cultured neuronal cells indicated the postsynaptic localization of TANC protein of 200 kDa. Pull-down experiments showed that TANC protein bound PSD-95, SAP97, and Homer via its C-terminal PDZ-binding motif, -ESNV, and fodrin via both its ankyrin repeats and the TPRs together with the coiled-coil domain. TANC also bound the alpha subunit of Ca2+/calmodulin-dependent protein kinase II. An immunoprecipitation study showed TANC association with various postsynaptic proteins, including guanylate kinase-associated protein (GKAP), alpha-internexin, and N-methyl-D-aspartate (NMDA)-type glutamate receptor 2B and AMPA-type glutamate receptor (GluR1) subunits. These results suggest that TANC protein may work as a postsynaptic scaffold component by forming a multiprotein complex with various postsynaptic density proteins.

    The European journal of neuroscience 2005;21;2;339-50

  • SynGAP-MUPP1-CaMKII synaptic complexes regulate p38 MAP kinase activity and NMDA receptor-dependent synaptic AMPA receptor potentiation.

    Krapivinsky G, Medina I, Krapivinsky L, Gapon S and Clapham DE

    Howard Hughes Medical Institute, Children's Hospital, 1309 Enders Building, 320 Longwood Avenue, Boston, Massachusetts 02115, USA.

    The synapse contains densely localized and interacting proteins that enable it to adapt to changing inputs. We describe a Ca2+-sensitive protein complex involved in the regulation of AMPA receptor synaptic plasticity. The complex is comprised of MUPPI, a multi-PDZ domain-containing protein; SynGAP, a synaptic GTPase-activating protein; and the Ca2+/calmodulin-dependent kinase CaMKII. In synapses of hippocampal neurons, SynGAP and CaMKII are brought together by direct physical interaction with the PDZ domains of MUPP1, and in this complex, SynGAP is phosphorylated. Ca2+CaM binding to CaMKII dissociates it from the MUPP1 complex, and Ca2+ entering via the NMDAR drives the dephosphorylation of SynGAP. Specific peptide-induced SynGAP dissociation from the MUPP1-CaMKII complex results in SynGAP dephosphorylation accompanied by P38 MAPK inactivation, potentiation of synaptic AMPA responses, and an increase in the number of AMPAR-containing clusters in hippocampal neuron synapses. siRNA-mediated SynGAP knockdown confirmed these results. These data implicate SynGAP in NMDAR- and CaMKII-dependent regulation of AMPAR trafficking.

    Neuron 2004;43;4;563-74

  • Identification of novel phosphorylation sites on postsynaptic density proteins.

    Jaffe H, Vinade L and Dosemeci A

    Protein and Peptide Sequencing Facility, NIH/NINDS, Bethesda, MD, USA.

    Phosphorylation of the components of the postsynaptic density (PSD), a protein complex lining the postsynaptic membrane, may regulate synaptic structure and function. We carried out mass spectrometric analyses to identify phosphorylation sites on PSD proteins. Phosphopeptides were isolated from the total tryptic digest of a PSD fraction by immobilized metal affinity chromatography and analyzed by liquid chromatography and tandem mass spectrometry. The phosphorylated residues detected following in vitro phosphorylation in the presence of Ca2+/calmodulin included S-1058 on SynGAP and S-1662 and S-1668 on Shank3. Other phosphorylated residues were identified in control samples, presumably reflecting phosphorylation in the intact cell. These included the homologous residues, S-295 on PSD-95 and S-365 on PSD-93, located between the PDZ2 and PDZ3 domains of these proteins; and S-367 located on the actin-binding domain of beta-CaMKII. The sequence RXXSPV emerged as a common phosphorylation motif of three specialized PSD scaffolding proteins, PSD-95, PSD-93, and Shank3. Phosphorylated serine residues in several of the identified phosphorylation sites were followed by prolines, suggesting prominent involvement of proline directed kinases in the regulation of PSD components.

    Biochemical and biophysical research communications 2004;321;1;210-8

  • Regulation of the multifunctional Ca2+/calmodulin-dependent protein kinase II by the PP2C phosphatase PPM1F in fibroblasts.

    Harvey BP, Banga SS and Ozer HL

    Department of Microbiology and Molecular Genetics, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School and UMDNJ-Graduate School of Biomedical Sciences, Newark, New Jersey 07101, USA.

    The regulation of the multifunctional calcium/calmodulin dependent protein kinase II (CaMKII) by serine/threonine protein phosphatases has been extensively studied in neuronal cells; however, this regulation has not been investigated previously in fibroblasts. We cloned a cDNA from SV40-transformed human fibroblasts that shares 80% homology to a rat calcium/calmodulin-dependent protein kinase phosphatase that encodes a PPM1F protein. By using extracts from transfected cells, PPM1F, but not a mutant (R326A) in the conserved catalytic domain, was found to dephosphorylate in vitro a peptide corresponding to the auto-inhibitory region of CaMKII. Further analyses demonstrated that PPM1F specifically dephosphorylates the phospho-Thr-286 in autophosphorylated CaMKII substrate and thus deactivates the CaMKII in vitro. Coimmunoprecipitation of CaMKII with PPM1F indicates that the two proteins can interact intracellularly. Binding of PPM1F to CaMKII involves multiple regions and is not dependent on intact phosphatase activity. Furthermore, overexpression of PPM1F in fibroblasts caused a reduction in the CaMKII-specific phosphorylation of the known substrate vimentin(Ser-82) following induction of the endogenous CaM kinase. These results identify PPM1F as a CaM kinase phosphatase within fibroblasts, although it may have additional functions intracellularly since it has been presented elsewhere as POPX2 and hFEM-2. We conclude that PPM1F, possibly together with the other previously described protein phosphatases PP1 and PP2A, can regulate the activity of CaMKII. Moreover, because PPM1F dephosphorylates the critical autophosphorylation site of CaMKII, we propose that this phosphatase plays a key role in the regulation of the kinase intracellularly.

    Funded by: NCI NIH HHS: T32 CA09665; NIA NIH HHS: AG04821

    The Journal of biological chemistry 2004;279;23;24889-98

  • Regulation of the neuron-specific Ras GTPase-activating protein, synGAP, by Ca2+/calmodulin-dependent protein kinase II.

    Oh JS, Manzerra P and Kennedy MB

    Division of Biology 216-76, California Institute of Technology, Pasadena, California 91125, USA.

    synGAP is a neuron-specific Ras GTPase-activating protein found in high concentration in the postsynaptic density fraction from mammalian forebrain. Proteins in the postsynaptic density, including synGAP, are part of a signaling complex attached to the cytoplasmic tail of the N-methyl-d-aspartate-type glutamate receptor. synGAP can be phosphorylated by a second prominent component of the complex, Ca(2+)/calmodulin-dependent protein kinase II. Here we show that phosphorylation of synGAP by Ca(2+)/calmodulin-dependent protein kinase II increases its Ras GTPase-activating activity by 70-95%. We identify four major sites of phosphorylation, serines 1123, 1058, 750/751/756, and 764/765. These sites together with other minor phosphorylation sites in the carboxyl tail of synGAP control stimulation of GTPase-activating activity. When three of these sites and four other serines in the carboxyl tail are mutated, stimulation of GAP activity after phosphorylation is reduced to 21 +/- 5% compared with 70-95% for the wild type protein. We used phosphosite-specific antibodies to show that, as predicted, phosphorylation of serines 765 and 1123 is increased in cultured cortical neurons after exposure of the neurons to the agonist N-methyl-d-aspartate.

    Funded by: NINDS NIH HHS: NS17660, NS28710, R01 NS017660, R01 NS017660-21, R01 NS017660-22, R01 NS017660-23A2, R01 NS017660-24

    The Journal of biological chemistry 2004;279;17;17980-8

  • PSD-95 promotes CaMKII-catalyzed serine phosphorylation of the synaptic RAS-GTPase activating protein SynGAP after transient brain ischemia in rat hippocampus.

    Song B, Yan XB and Zhang GY

    Research Center of Biochemistry and Molecular Biology, Xuzhou Medical College, 84 West Huai-hai Road, Xuzhou 221002, Jiangsu, PR China.

    Recent studies have indicated that cerebral ischemia induces rapid serine phosphorylation of synaptic RAS-GTPase activating protein (SynGAP) by calcium/Camodulin-dependent protein kinase II (CaMKII) in rat hippocampus. To further illustrate the mechanisms underlying these processes, we examined the effects of transient (15 min) brain ischemia followed by reperfusion (0, 30 min, 6 h, 1, 3 days) on serine phosphorylation of SynGAP and interactions involving SynGAP, postsynaptic density protein 95 (PSD95) and CaMKII in rat hippocampus. Transient brain ischemia was induced by the method of four-vessel occlusion in Sprague-Dawley rats. Serine phosphorylation of SynGAP increased immediately after brain ischemia and peaked at 30-min reperfusion, and the increase was maintained for 3 days. The association among SynGAP, PSD95 and CaMKII had a similar trend as serine phosphorylation of SynGAP. Intracrebroventricular infusion of PSD95 antisense oligodeoxynucleotide not only markedly decreased the protein levels of PSD95 but also attenuated the elevated serine phosphorylation of SynGAP and the associations among SynGAP, PSD95 and CaMKII induced by 30-min reperfusion following 15-min brain ischemia. The results suggest that the serine phosphorylation of SynGAP catalyzed by CaMKII is immediately increased and that PSD95 is critical for promoting SynGAP serine phosphorylation after transient brain ischemia.

    Brain research 2004;1005;1-2;44-50

  • Comparative analyses of the three-dimensional structures and enzymatic properties of alpha, beta, gamma and delta isoforms of Ca2+-calmodulin-dependent protein kinase II.

    Gaertner TR, Kolodziej SJ, Wang D, Kobayashi R, Koomen JM, Stoops JK and Waxham MN

    Department of Neurobiology and Anatomy, University of Texas Medical School, 6431 Fannin Street, Houston, TX 77030, USA.

    Ca(2+)-calmodulin-dependent protein kinase II (CaM-kinase II) is a ubiquitous Ser/Thr-directed protein kinase that is expressed from a family of four genes (alpha, beta, gamma, and delta) in mammalian cells. We have documented the three-dimensional structures and the biophysical and enzymatic properties of the four gene products. Biophysical analyses showed that each isoform assembles into oligomeric forms and their three-dimensional structures at 21-25 A revealed that all four isoforms were dodecamers with similar but highly unusual architecture. A gear-shaped core comprising the association domain has the catalytic domains tethered on appendages, six of which extend from both ends of the core. At this level of resolution, we can discern no isoform-dependent differences in ultrastructure of the holoenzymes. Enzymatic analyses showed that the isoforms were similar in their K(m) for ATP and the peptide substrate syntide, but showed significant differences in their interactions with Ca(2+)-calmodulin as assessed by binding, substrate phosphorylation, and autophosphorylation. Interestingly, the rank order of CaM binding affinity (gamma > beta > delta > alpha) does not directly correlate with the rank order of their CaM dependence for autophosphorylation (beta > gamma > delta > alpha). Simulations utilizing this data revealed that the measured differences in CaM binding affinities play a minor role in the autophosphorylation of the enzyme, which is largely dictated by the rate of autophosphorylation for each isoform.

    Funded by: NINDS NIH HHS: NS 26086

    The Journal of biological chemistry 2004;279;13;12484-94

  • Calcium/calmodulin-dependent protein kinase II binds to Raf-1 and modulates integrin-stimulated ERK activation.

    Illario M, Cavallo AL, Bayer KU, Di Matola T, Fenzi G, Rossi G and Vitale M

    Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università Federico II, Napoli, 80131 Italy.

    Integrin activation generates different signalings in a cell type-dependent manner and stimulates cell proliferation through the Ras/Raf-1/Mek/Erk pathway. In this study, we demonstrate that integrin stimulation by fibronectin (FN), besides activating the Ras/Erk pathway, generates an auxiliary calcium signal that activates calmodulin and the Ca2+/calmodulin-dependent protein kinase II (CaMKII). This signal regulates Raf-1 activation by Ras and modulates the FN-stimulated extracellular signal-regulated kinase (Erk-1/2). The binding of soluble FN to integrins induced increase of intracellular calcium concentration associated with phosphorylation and activation of CaMKII. In two different cell lines, inhibition of CaMKII activity by specific inhibitors inhibited Erk-1/2 phosphorylation. Whereas CaMK inhibition affected neither integrin-stimulated Akt phosphorylation nor p21Ras or Mek-1 activity, it was necessary for Raf-1 activity. FN-induced Raf-1 activity was abrogated by the CaMKII specific inhibitory peptide ant-CaNtide. Integrin activation by FN induced the formation of a Raf-1/CaMKII complex, abrogated by inhibition of CaMKII. Active CaMKII phosphorylated Raf-1 in vitro. This is the first demonstration that CaMKII interplays with Raf-1 and regulates Erk activation induced by Ras-stimulated Raf-1. These findings also provide evidence supporting the possible existence of cross-talk between other intracellular pathways involving CaMKII and Raf-1.

    The Journal of biological chemistry 2003;278;46;45101-8

  • The NMDA receptor is coupled to the ERK pathway by a direct interaction between NR2B and RasGRF1.

    Krapivinsky G, Krapivinsky L, Manasian Y, Ivanov A, Tyzio R, Pellegrino C, Ben-Ari Y, Clapham DE and Medina I

    Howard Hughes Medical Institute, Children's Hospital, 1309 Enders Building, 320 Longwood Avenue, Boston, MA 02115, USA.

    The NMDA subtype of glutamate receptors (NMDAR) at excitatory neuronal synapses plays a key role in synaptic plasticity. The extracellular signal-regulated kinase (ERK1,2 or ERK) pathway is an essential component of NMDAR signal transduction controlling the neuroplasticity underlying memory processes, neuronal development, and refinement of synaptic connections. Here we show that NR2B, but not NR2A or NR1 subunits of the NMDAR, interacts in vivo and in vitro with RasGRF1, a Ca(2+)/calmodulin-dependent Ras-guanine-nucleotide-releasing factor. Specific disruption of this interaction in living neurons abrogates NMDAR-dependent ERK activation. Thus, RasGRF1 serves as NMDAR-dependent regulator of the ERK kinase pathway. The specific association of RasGRF1 with the NR2B subunit and study of ERK activation in neurons with varied content of NR2B suggests that NR2B-containing channels are the dominant activators of the NMDA-dependent ERK pathway.

    Neuron 2003;40;4;775-84

  • CaMKII-dependent phosphorylation regulates SAP97/NR2A interaction.

    Gardoni F, Mauceri D, Fiorentini C, Bellone C, Missale C, Cattabeni F and Di Luca M

    Center of Excellence on Neurodegenerative Diseases and Department of Pharmacological Sciences, University of Milano, via Balzaretti 9, 20133 Milano, Italy. Fabrizio.Gardoni@unimi.it

    Synapse-associated protein 97 (SAP97), a member of membrane-associated guanylate kinase protein family, has been implicated in the processes of targeting ionotropic glutamate receptors at postsynaptic sites. Here we show that SAP97 is enriched at the postsynaptic density where it co-localizes with both ionotropic glutamate receptors and downstream signaling proteins such as Ca2+/calmodulin-dependent protein kinase II (CaMKII). SAP97 and alphaCaMKII display a high co-localization pattern in hippocampal neurons as well as in transfected COS-7 cells. Metabolic labeling of hippocampal cultures reveals that N-methyl-D-aspartic acid (NMDA) receptor activation induces CaMKII-dependent phosphorylation of SAP97; co-incubation with the CaMKII-specific inhibitor KN-93 reduces SAP97 phosphorylation to basal levels. Our results show that SAP97 directly interacts with the NR2A subunit of NMDA receptor both in an in vitro "pull-out" assay and in co-immunoprecipitation experiments from homogenates and synaptosomes purified from hippocampal rat tissue. Interestingly, in the postsynaptic density fraction, SAP97 fails to co-precipitate with NR2A. We show here that SAP97 is directly associated with NR2A through its PDZ1 domain, and CaMKII-dependent phosphorylation of SAP97-Ser-232 disrupts NR2A interaction both in an in vitro pull-out assay and in transfected COS-7 cells. Moreover, expression of SAP97(S232D) mutant has effects similar to those observed upon constitutively activating CaMKII. Our findings suggest that SAP97/NR2A interaction is regulated by CaMKII-dependent phosphorylation and provide a novel mechanism for the regulation of synaptic targeting of NMDA receptor subunits.

    The Journal of biological chemistry 2003;278;45;44745-52

  • Cerebral ischemia immediately increases serine phosphorylation of the synaptic RAS-GTPase activating protein SynGAP by calcium/calmodulin-dependent protein kinase II alpha in hippocampus of rats.

    Song B, Meng F, Yan X, Guo J and Zhang G

    Research Center of Biochemistry and Molecular Biology, Xuzhou Medical College, 84 West Huai-hai Road, Xuzhou 221002, Jiangsu, PR China.

    The interaction between translocated calcium/calmdulin-dependent protein kinase IIalpha (CaMK IIalpha) and SynGAP during brain ischemia was investigated by Western blotting and immunoprecipitation. Brain ischemia was induced by the four-vessel occlusion method on Sprague-Dawley rats. After 3 min global ischemia, both the binding of CaMK IIalpha to SynGAP and the serine phosphorylation of SynGAP all dramatically increased. Administrating KN-62 through cerebral ventricle (20 min before ischemia) not only remarkably decreased the binding of CaMK IIalpha to SynGAP but also attenuate the elevated serine phosphorylation of SynGAP following 20 min ischemia in hippocampus. These results suggest that CaMK IIalpha is responsible for the serine phosphorylation of SynGAP and a consequent phosphorylation and inhibition of SynGAP may result in activation of mitogen-activated protein kinase pathway which could serve a protective function in brain ischemia.

    Neuroscience letters 2003;349;3;183-6

  • Rim, a component of the presynaptic active zone and modulator of exocytosis, binds 14-3-3 through its N terminus.

    Sun L, Bittner MA and Holz RW

    Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0632, USA.

    Rim1, a brain-specific Rab3a-binding protein, localizes to the presynaptic cytomatrix and plays an important role in synaptic transmission and synaptic plasticity. Rim2, a homologous protein, is more ubiquitously expressed and is found in neuroendocrine cells as well as in brain. Both Rim1 and Rim2 contain multiple domains, including an N-terminal zinc finger, which in Rim1 strongly enhances secretion in chromaffin and PC12 cells. The yeast two-hybrid technique identified 14-3-3 proteins as ligands of the N-terminal domain. In vitro protein binding experiments confirmed a high-affinity interaction between the N terminus of Rim1 and 14-3-3. The N-terminal domain of Rim2 also bound 14-3-3. The binding domains were localized to a short segment just C-terminal to the zinc finger. 14-3-3 proteins bind to specific phosphoserine residues. Alkaline phosphatase treatment of N-terminal domains of Rim1 and Rim2 almost completely inhibited the binding of 14-3-3. Two serine residues in Rim1 (Ser-241 and Ser-287) and one serine residue in Rim2 (Ser-335) were required for 14-3-3 binding. Incubation with Ca2+/calmodulin-dependent protein kinase II greatly stimulated the interaction of recombinant N-terminal Rim but not the S241/287A mutant with 14-3-3, again indicating the importance of the phosphorylation of these residues for the binding. Rabphilin3, another Rab3a effector, also bound 14-3-3. Serine-to-alanine mutations identified Ser-274 as the likely phosphorylated residue to which 14-3-3 binds. Because the phosphorylation of this residue had been shown to be stimulated upon depolarization in brain slices, the interaction of 14-3-3 with Rabphilin3 may be important in the dynamic function of central nervous system neurons.

    Funded by: NIDDK NIH HHS: R01-DK50177

    The Journal of biological chemistry 2003;278;40;38301-9

  • Activation of peripheral NMDA receptors contributes to human pain and rat afferent discharges evoked by injection of glutamate into the masseter muscle.

    Cairns BE, Svensson P, Wang K, Hupfeld S, Graven-Nielsen T, Sessle BJ, Berde CB and Arendt-Nielsen L

    Department of Anesthesia, Harvard Medical School/Children's Hospital, Boston, Massachusetts 02115, USA.

    Peripheral N-methyl-d-aspartate (NMDA) receptors are found in deep tissues and may play a role in deep tissue pain. Injection of the endogenous NMDA receptor agonist glutamate into the masseter muscle excites deep craniofacial afferent fibers in rats and evokes pain in human subjects. It is not clear whether peripheral NMDA receptors play a role in these effects of glutamate. Accordingly, the effect of NMDA on afferent activity as well as the effect of locally administered NMDA receptor antagonists on glutamate-evoked afferent discharges in acutely anesthetized rats and muscle pain in human subjects was examined. Injection of NMDA into the masseter muscle evoked afferent discharges in a concentration-related manner. It was found that the NMDA receptor antagonists 2-amino-5-phosphonvalerate (APV, 10 mM), ketamine (10 mM), and dextromethorphan (40 mM) significantly decreased glutamate-evoked afferent discharges. The effects of APV and ketamine, but not dextromethorphan, were selective for glutamate-evoked afferent discharges and did not affect hypertonic saline-evoked afferent discharges. In human experiments, it was found that 10 mM ketamine decreased glutamate-evoked muscle pain but had no effect on hypertonic saline-evoked muscle pain. These results indicate that injection of glutamate into the masseter muscle evokes afferent discharges in rats and muscle pain in humans in part through activation of peripheral NMDA receptors. It is conceivable that activation of peripheral NMDA receptors may contribute to masticatory muscle pain and that peripherally acting NMDA receptor antagonists could prove to be effective analgesics for this type of pain.

    Journal of neurophysiology 2003;90;4;2098-105

  • Post-synaptic density-95 promotes calcium/calmodulin-dependent protein kinase II-mediated Ser847 phosphorylation of neuronal nitric oxide synthase.

    Watanabe Y, Song T, Sugimoto K, Horii M, Araki N, Tokumitsu H, Tezuka T, Yamamoto T and Tokuda M

    Department of Cell Physiology, Kagawa Medical University, 1750-1 Ikenobe, Miki-cho, Kida-gun, Japan. yasuwata@kms.ac.jp

    Post-synaptic density-95 (PSD-95) is a neuronal scaffolding protein that associates with N -methyl-D-aspartate (NMDA) receptors and links them to intracellular signalling molecules. In neurons, neuronal nitric oxide synthase (nNOS) binds selectively to the second PDZ domain (PDZ2) of PSD-95, thereby exhibiting physiological activation triggered via NMDA receptors. We have demonstrated previously that Ca(2+)/calmodulin-dependent protein kinase IIalpha (CaM-K IIalpha) directly phosphorylates nNOS at residue Ser(847), and can attenuate the catalytic activity of the enzyme in neuronal cells [Komeima, Hayashi, Naito and Watanabe (2000) J. Biol. Chem. 275, 28139-28143]. In the present study, we examined how CaM-K II participates in the phosphorylation by analysing the functional interaction between nNOS and PSD-95 in cells. The results showed that PSD-95 directly promotes the nNOS phosphorylation at Ser(847) induced by endogenous CaM-K II. In transfected cells, this effect of PSD-95 required its dual palmitoylation and the PDZ2 domain, but did not rely on its guanylate kinase domain. CaM-K Ialpha and CaM-K IV failed to phosphorylate nNOS at Ser(847) in transfected cells. Thus PSD-95 mediates cellular trafficking of nNOS, and may be required for the efficient phosphorylation of nNOS at Ser(847) by CaM-K II in neuronal cells.

    The Biochemical journal 2003;372;Pt 2;465-71

  • Phosphorylation of 69-kDa choline acetyltransferase at threonine 456 in response to amyloid-beta peptide 1-42.

    Dobransky T, Brewer D, Lajoie G and Rylett RJ

    Department of Physiology, University of Western Ontario, and Robarts Research Institute, London, Ontario N6A 5C1, Canada.

    Choline acetyltransferase synthesizes acetylcholine in cholinergic neurons. In the brain, these neurons are especially vulnerable to effects of beta-amyloid (A beta) peptides. Choline acetyltransferase is a substrate for several protein kinases. In the present study, we demonstrate that short term exposure of IMR32 neuroblastoma cells expressing human choline acetyltransferase to A beta-(1-42) changes phosphorylation of the enzyme, resulting in increased activity and alterations in its interaction with other cellular proteins. Using mass spectrometry, we identified threonine 456 as a new phosphorylation site in choline acetyltransferase from A beta-(1-42)-treated cells and in purified recombinant ChAT phosphorylated in vitro by calcium/calmodulin-dependent protein kinase II (CaM kinase II). Whereas phosphorylation of choline acetyltransferase by protein kinase C alone caused a 2-fold increase in enzyme activity, phosphorylation by CaM kinase II alone did not alter enzyme activity. A 3-fold increase in choline acetyltransferase activity was found with coordinate phosphorylation of threonine 456 by CaM kinase II and phosphorylation of serine 440 by protein kinase C. This phosphorylation combination was observed in choline acetyltransferase from A beta-(1-42)-treated cells. Treatment of cells with A beta-(1-42) resulted in two phases of activation of choline acetyltransferase, the first within 30 min and associated with phosphorylation by protein kinase C and the second by 10 h and associated with phosphorylation by both CaM kinase II and protein kinase C. We also show that choline acetyltransferase from A beta-(1-42)-treated cells co-immunoprecipitates with valosin-containing protein, and mutation of threonine 456 to alanine abolished the A beta-(1-42)-induced effects. These studies demonstrate that A beta-(1-42) can acutely regulate the function of choline acetyltransferase, thus potentially altering cholinergic neurotransmission.

    The Journal of 1f40 biological chemistry 2003;278;8;5883-93

  • Calcium regulation of GM-CSF by calmodulin-dependent kinase II phosphorylation of Ets1.

    Liu H and Grundström T

    Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden.

    The multipotent cytokine granulocyte macrophage-colony stimulating factor (GM-CSF) is involved in particular in the physiological response to infection and in inflammatory responses. GM-CSF is produced by many cell types, including T lymphocytes responding to T-cell receptor activation and mantle zone B lymphocytes. B-cell receptor and T-cell receptor activation generates two major signals: an increase in intracellular Ca(2+) concentration and a protein kinase cascade. Previous studies have shown that the Ca(2+)/calmodulin-dependent phosphatase calcineurin mediates stimulation of GM-CSF transcription in response to Ca(2+). In this study, we show that Ca(2+) signaling also regulates GM-CSF transcription negatively through Ca(2+)/calmodulin-dependent kinase II (CaMK II) phosphorylation of serines in the autoinhibitory domain for DNA binding of the transcription factor Ets1. Wild-type Ets1 negatively affects GM-CSF transcription on Ca(2+) stimulation in the presence of cyclosporin A, which inhibits calcineurin. Conversely, Ets1 with mutated CaMK II target serines showed an increase in transactivation of the GM-CSF promoter/enhancer. Moreover, constitutively active CaMK II inhibited transactivation of GM-CSF by wild-type Ets1 but not by Ets1 with mutated CaMK II sites. Mutation of CaMK II target serines in Ets1 also relieves inhibition of cooperative transactivation of GM-CSF with the Runx1/AML1 transcription factor. In addition, the Ca(2+)-dependent phosphorylation of Ets1 reduces the binding of Ets1 to the GM-CSF promoter in vivo.

    Molecular biology of the cell 2002;13;12;4497-507

  • Inhibitory autophosphorylation of CaMKII controls PSD association, plasticity, and learning.

    Elgersma Y, Fedorov NB, Ikonen S, Choi ES, Elgersma M, Carvalho OM, Giese KP and Silva AJ

    Department of Neurobiology, Department of Psychiatry, Department of Psychology, Brain Research Institute, University of California, Los Angeles, CA 90095, USA.

    To investigate the function of the alpha calcium-calmodulin-dependent kinase II (alphaCaMKII) inhibitory autophosphorylation at threonines 305 and/or 306, we generated knockin mice that express alphaCaMKII that cannot undergo inhibitory phosphorylation. In addition, we generated mice that express the inhibited form of alphaCaMKII, which resembles the persistently phosphorylated kinase at these sites. Our data demonstrate that blocking inhibitory phosphorylation increases CaMKII in the postsynaptic density (PSD), lowers the threshold for hippocampal long-term potentiation (LTP), and results in hippocampal-dependent learning that seems more rigid and less fine-tuned. Mimicking inhibitory phosphorylation dramatically decreased the association of CaMKII with the PSD and blocked both LTP and learning. These data demonstrate that inhibitory phosphorylation has a critical role in plasticity and learning.

    Funded by: NIA NIH HHS: AG 13622

    Neuron 2002;36;3;493-505

  • Involvement of aberrant glycosylation in phosphorylation of tau by cdk5 and GSK-3beta.

    Liu F, Iqbal K, Grundke-Iqbal I and Gong CX

    Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island 10314, USA.

    Microtubule-associated protein tau is abnormally hyperphosphorylated, glycosylated, and aggregated in affected neurons in the brains of individuals with Alzheimer's disease (AD). We recently found that the glycosylation might precede hyperphosphorylation of tau in AD. In this study, we investigated the effect of glycosylation on phosphorylation of tau catalyzed by cyclin-dependent kinase 5 (cdk5) and glycogen synthase kinase-3beta (GSK-3beta). The phosphorylation of the longest isoform of recombinant human brain tau, tau(441), at various sites was detected by Western blots and by radioimmuno-dot-blot assay with phosphorylation-dependent and site-specific tau antibodies. We found that cdk5 phosphorylated tau(441) at Thr-181, Ser-199, Ser-202, Thr-205, Thr-212, Ser-214, Thr-217, Thr-231, Ser-235, Ser-396, and Ser-404, but not at Ser-262, Ser-400, Thr-403, Ser-409, Ser-413, or Ser-422. GSK-3beta phosphorylated all the cdk5-catalyzed sites above except Ser-235. Deglycosylation by glycosidases depressed the subsequent phosphorylation of AD-tau (i) with cdk5 at Thr-181, Ser-199, Ser-202, Thr-205, and Ser-404, but not at Thr-212; and (ii) with GSK-3beta at Thr-181, Ser-202, Thr-205, Ser-217, and Ser-404, but not at Ser-199, Thr-212, Thr-231, or Ser-396. These data suggest that aberrant glycosylation of tau in AD might be involved in neurofibrillary degeneration by promoting abnormal hyperphosphorylation by cdk5 and GSK-3beta.

    Funded by: NIA NIH HHS: AG16760, AG19158; NINDS NIH HHS: MN/NS 31862

    FEBS letters 2002;530;1-3;209-14

  • The cyclin-dependent kinase 5 activators p35 and p39 interact with the alpha-subunit of Ca2+/calmodulin-dependent protein kinase II and alpha-actinin-1 in a calcium-dependent manner.

    Dhavan R, Greer PL, Morabito MA, Orlando LR and Tsai LH

    Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.

    Cyclin-dependent kinase 5 (Cdk5) is a critical regulator of neuronal migration in the developing CNS, and recent studies have revealed a role for Cdk5 in synaptogenesis and regulation of synaptic transmission. Deregulation of Cdk5 has been linked to the pathology of neurodegenerative diseases such as Alzheimer's disease. Activation of Cdk5 requires its association with a regulatory subunit, and two Cdk5 activators, p35 and p39, have been identified. To gain further insight into the functions of Cdk5, we identified proteins that interact with p39 in a yeast two-hybrid screen. In this study we report that alpha-actinin-1 and the alpha-subunit of Ca2+/calmodulin-dependent protein kinase II (CaMKIIalpha), two proteins localized at the postsynaptic density, interact with Cdk5 via their association with p35 and p39. CaMKIIalpha and alpha-actinin-1 bind to distinct regions of p35 and p39 and also can interact with each other. The association of CaMKIIalpha and alpha-actinin-1 to the Cdk5 activators, as well as to each other, is stimulated by calcium. Further, the activation of glutamate receptors increases the association of p35 and p39 with CaMKIIalpha, and the inhibition of CaMKII activation diminishes this effect. The glutamate-mediated increase in association of p35 and CaMKIIalpha is mediated in large part by NMDA receptors, suggesting that cross talk between the Cdk5 and CaMKII signal transduction pathways may be a component of the complex molecular mechanisms contributing to synaptic plasticity, memory, and learning.

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2002;22;18;7879-91

  • Sequence determinants on the NR2A and NR2B subunits of NMDA receptor responsible for specificity of phosphorylation by CaMKII.

    Mayadevi M, Praseeda M, Kumar KS and Omkumar RV

    Rajiv Gandhi Centre for Biotechnology, Jagathy, Thiruvananthapuam, Kerala-695014, India.

    Calcium/calmodulin-dependent protein kinase type II (CaMKII) and NMDA-type glutamate receptor (NMDAR) are neuronal proteins involved in learning and memory. CaMKII binds to the NR2B subunit of NMDAR in more than one mode, a stable association involving a noncatalytic site on CaMKII and an enzyme-substrate mode of interaction by its catalytic site. The latter binding results in phosphorylation of serine-1303 on NR2B. We have investigated this binding by studying the kinetics of phosphorylation of synthetic peptides harboring nested sequences of the phosphorylation site motif. We find that residues 1292-1297 of NR2B enhance the affinity of the catalytic site-mediated binding of CaMKII to the minimal phosphorylation site motif, 1298-1308 of NR2B, as evident from measurements of K(m) values for phosphorylation. However, CaMKII shows decreased affinity towards the closely related NR2A subunit due to an -Ile-Asn- motif present as a natural insertion in the analogous sequence on NR2A.

    Biochimica et biophysica acta 2002;1598;1-2;40-5

  • Decreased prefrontal CaMKII alpha mRNA in bipolar illness.

    Xing G, Russell S, Hough C, O'Grady J, Zhang L, Yang S, Zhang LX and Post R

    Department of Psychiatry, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.

    Ca2+/calmodulin-dependent protein kinase II (CaMKII) plays critical roles in neurotransmission, synaptic plasticity, learning and memory. The aim of this study was to examine, by in situ hybridization, prefrontal cortical expression of CaMKII alpha mRNA in postmortem brains of unipolar, bipolar, schizophrenic, and control subjects. Compared to controls, bipolar patients had significantly lower levels of CaMKII alpha mRNA in laminae I-VI of Brodmann's area 9 and laminae I-III and VI of area 46. Unipolar patients also exhibited significantly lower levels of CaMKII alpha mRNA in laminae I-IV of area 9 than did controls. The significant decrease in CaMKII alpha mRNA in bipolar patients could be associated with some of the affective and cognitive alterations that have been linked to prefrontal cortical dysfunction in bipolar disorder, although this requires further direct examination.

    Neuroreport 2002;13;4;501-5

  • Beta(3)-mediated engulfment of apoptotic tumor cells by dendritic cells is dependent on CAMKII: inhibition by HIV-1 Tat.

    Poggi A, Carosio R, Rubartelli A and Zocchi MR

    Laboratory of Immunology, Unit of Protein Biology, National Cancer Research Institute, Genoa, Italy.

    In this paper, we show that the engulfment of apoptotic tumor cells by DC requires the activation of the calcium-calmodulin kinase II (CAMKII). Indeed, DC phagocytosis of apoptotic lymphoma cells is consistently inhibited by KN62 and KN93, two blockers of CAMKII, but not by the inactive compound KN92. Wortmannin and LY294002, two inhibitors of the phosphatidyl-inositol-3 kinase, slightly decrease the phagocytosis of apoptotic cells, at variance with PD98059, an inhibitor of the mitogen-activated protein kinase. It is interesting that the addition of synthetic HIV-1 Tat, which we demonstrated to inhibit phagocytosis and calcium influx in DC, blocks the activation of CAMKII elicited via beta(3) integrin, which is involved in apoptotic body engulfment by DC. Experiments performed with Tat-derived peptides showed that this inhibition is mediated by the C-terminal domain of Tat. Finally, pertussis toxin can prevent HIV-1 Tat-mediated inhibition, suggesting the involvement of a guanosine triphosphate-binding (G) protein in DC-mediated phagocytosis.

    Journal of leukocyte biology 2002;71;3;531-7

  • [Molecular mechanisms of the intracellular localizations of Ca2+/calmodulin-dependent protein kinase II isoforms, and their physiological functions].

    Yamamoto H

    hideyuki@gpo.kumamoto-u.ac.jp

    Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme 2002;47;3;241-7

  • Parkin and CASK/LIN-2 associate via a PDZ-mediated interaction and are co-localized in lipid rafts and postsynaptic densities in brain.

    Fallon L, Moreau F, Croft BG, Labib N, Gu WJ and Fon EA

    Centre for Neuronal Survival, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada.

    Mutations in the gene encoding parkin cause an autosomal recessive juvenile-onset form of Parkinson's disease. Parkin functions as a RING-type E3 ubiquitin-ligase, coordinating the transfer of ubiquitin to substrate proteins and thereby targeting them for degradation by the proteasome. We now report that the extreme C terminus of parkin, which is selectively truncated by a Parkinson's disease-causing mutation, functions as a class II PDZ-binding motif that binds CASK, the mammalian homolog of Caenorhabditis elegans Lin-2, but not other PDZ proteins in brain extracts. Importantly, parkin co-localizes with CASK at synapses in cultured cortical neurons as well as in postsynaptic densities and lipid rafts in brain. Further, parkin associates not only with CASK but also with other postsynaptic proteins in the N-methyl d-aspartate (NMDA) receptor-signaling complex, in rat brain in vivo. Finally, despite exhibiting E2-dependent ubiquitin ligase activity, rat brain parkin does not ubiquitinate CASK, suggesting that CASK may function in targeting or scaffolding parkin within the postsynaptic complex rather than as a direct substrate for parkin-mediated ubiquitination. These data implicate for the first time a PDZ-mediated interaction between parkin and CASK in neurodegeneration and possibly in ubiquitination of proteins involved in synaptic transmission and plasticity.

    The Journal of biological chemistry 2002;277;1;486-91

  • NK cell activation by dendritic cells is dependent on LFA-1-mediated induction of calcium-calmodulin kinase II: inhibition by HIV-1 Tat C-terminal domain.

    Poggi A, Carosio R, Spaggiari GM, Fortis C, Tambussi G, Dell'Antonio G, Dal Cin E, Rubartelli A and Zocchi MR

    Laboratory of Immunology, National Institute for Cancer Research, Genoa, Italy.

    In this study, we show that binding to autologous dendritic cells (DC) induces a calcium influx in NK cells, followed by activation of the calcium-calmodulin kinase II (CAMKII), release of perforin and granzymes, and IFN-gamma secretion. CAMKII is induced via LFA-1: indeed, oligomerization of LFA-1 leads to CAMKII induction in NK cells. Moreover, release of lytic enzymes and cytotoxic activity is strongly reduced by masking LFA-1 or by adding CAMKII inhibitors such as KN62 and KN93, at variance with the inactive compound KN92. NK cell-mediated lysis of DC and IFN-gamma release by NK cells upon NK/DC contact are inhibited by exogenous HIV-1 Tat: the protein blocks calcium influx and impairs CAMKII activation elicited via LFA-1 in NK cells, eventually inhibiting degranulation. Experiments performed with synthetic, overlapping Tat-derived peptides showed that the C-terminal domain of the protein is responsible for inhibition. Finally, both KN62 and Tat reduced the extension of NK/DC contacts, possibly affecting NK cell granule polarization toward the target. These data provide evidence that exogenous Tat inhibits NK cell activation occurring upon contact with DC: this mechanism might contribute to the impairment of natural immunity in HIV-1 infection.

    Journal of immunology (Baltimore, Md. : 1950) 2002;168;1;95-101

  • Predominant role by CaM kinase in NPY Y(1) receptor signaling: involvement of CREB [corrected].

    Sheriff S, F Qureshy A, T Chance W, Kasckow JW and Balasubramaniam A

    Department of Surgery, College of Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267, USA. sherifs@email.uc.edu

    The role of Ca(2+)/cAMP-dependent signal transduction and transcription factor CREB in mediating NPY- Y(1) receptor function was investigated in SK-N-MC cells. The Y(1) receptor agonist, [Leu(31),Pro(34)]-NPY, inhibited forskolin-stimulated cAMP production which was insensitive to thapsigargin or the CaM kinase II inhibitor, KN-93. Although activation of the Y(1) receptor leads to an increase in CREB phosphorylation, [Leu(31),Pro(34)]-NPY inhibited CREB phosphorylation in KN-93-treated cells. SK-N-MC cells were also transfected with PathDetect cis-CRE and trans-CREB/trans-cFos reporter genes to monitor the role of Ca(2+)/cAMP signals, triggered by Y(1) receptor, on reporter gene activity. Treatment of the cis-CRE-luciferase expression vector-transfected cells with [Leu(31),Pro(34)]-NPY increased reporter gene activity by 2 fold through a KN-93 sensitive pathway. In contrast, the peptide inhibited forskolin-stimulated luciferase activity. Consistently, [Leu(31),Pro(34)]-NPY induced trans-CREB mediated luciferase activity through a CaM kinase dependent pathway, and inhibited forskolin-stimulated luciferase gene expression. However, no effect of the peptide was observed on trans-cFos- mediated luciferase activity. These findings suggest that the NPY Y(1) receptor induces the expression of CRE containing target genes through the CaM kinase-CREB pathway, and inhibits CRE containing genes when cellular cAMP levels are elevated.

    Funded by: NIDDK NIH HHS: R01 DK-53548; NIGMS NIH HHS: GM-47122

    Peptides 2002;23;1;87-96

  • Aberrant glycosylation modulates phosphorylation of tau by protein kinase A and dephosphorylation of tau by protein phosphatase 2A and 5.

    Liu F, Zaidi T, Iqbal K, Grundke-Iqbal I and Gong CX

    Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, , Staten Island, NY 10314, USA.

    Microtubule-associated protein tau is abnormally hyperphosphorylated, glycosylated, and aggregated in affected neurons in Alzheimer's disease (AD). We recently found that the aberrant tau glycosylation precedes tau hyperphosphorylation in AD brain. In the present study, we developed assays to determine phosphorylation and dephosphorylation of tau at specific phosphorylation sites by using glycosylated tau purified from AD brain as a substrate. We then studied the effects of the aberrant glycosylation on phosphorylation and dephosphorylation of tau at each specific phosphorylation site. We found that deglycosylation of the aberrantly glycosylated tau decreased the subsequent phosphorylation of tau at Ser214, Ser262, and Ser356 in vitro by protein kinase A. On the other hand, deglycosylation of tau positively modulated the subsequent dephosphorylation by protein phosphatase 2A and protein phosphatase 5 in vitro at the phosphorylation sites Ser198, Ser199, and Ser202. Our results suggest that the aberrant glycosylation may modulate tau protein at a substrate level so that it is easier to be phosphorylated and more difficult to be dephosphorylated at some phosphorylation sites in AD brain. The combined impact of this modulation may be to make tau more susceptible to becoming abnormally hyperphosphorylated.

    Funded by: NIA NIH HHS: AG05892, AG08076, AG16760; NINDS NIH HHS: MN/NS31862, NS18105

    Neuroscience 2002;115;3;829-37

  • Inositol 1,4,5-trisphosphate 3-kinase A associates with F-actin and dendritic spines via its N terminus.

    Schell MJ, Erneux C and Irvine RF

    Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QJ, United Kingdom. mjs54@cus.cam.ac.uk

    The consequences of the rapid 3-phosphorylation of inositol 1,4,5-trisphosphate (IP(3)) to produce inositol 1,3,4,5-tetrakisphosphate (IP(4)) via the action of IP(3) 3-kinases involve the control of calcium signals. Using green fluorescent protein constructs of full-length and truncated IP(3) 3-kinase isoform A expressed in HeLa cells, COS-7 cells, and primary neuronal cultures, we have defined a novel N-terminal 66-amino acid F-actin-binding region that localizes the kinase to dendritic spines. The region is necessary and sufficient for binding F-actin and consists of a proline-rich stretch followed by a predicted alpha-helix. We also localized endogenous IP(3) 3-kinase A to the dendritic spines of pyramidal neurons in primary hippocampal cultures, where it is co-localized postsynaptically with calcium/calmodulin-dependent protein kinase II. Our experiments suggest a link between inositol phosphate metabolism, calcium signaling, and the actin cytoskeleton in dendritic spines. The phosphorylation of IP(3) in dendritic spines to produce IP(4) is likely to be important for modulating the compartmentalization of calcium at synapses.

    The Journal of biological chemistry 2001;276;40;37537-46

  • Phosphorylation of serine 230 promotes inducible transcriptional activity of heat shock factor 1.

    Holmberg CI, Hietakangas V, Mikhailov A, Rantanen JO, Kallio M, Meinander A, Hellman J, Morrice N, MacKintosh C, Morimoto RI, Eriksson JE and Sistonen L

    Turku Centre for Biotechnology, University of Turku, Abo Akademi University, Finland.

    Heat shock factor 1 (HSF1) is a serine-rich constitutively phosphorylated mediator of the stress response. Upon stress, HSF1 forms DNA-binding trimers, relocalizes to nuclear granules, undergoes inducible phosphorylation and acquires the properties of a transactivator. HSF1 is phosphorylated on multiple sites, but the sites and their function have remained an enigma. Here, we have analyzed sites of endogenous phosphorylation on human HSF1 and developed a phosphopeptide antibody to identify Ser230 as a novel in vivo phosphorylation site. Ser230 is located in the regulatory domain of HSF1, and promotes the magnitude of the inducible transcriptional activity. Ser230 lies within a consensus site for calcium/calmodulin-dependent protein kinase II (CaMKII), and CaMKII overexpression enhances both the level of in vivo Ser230 phosphorylation and transactivation of HSF1. The importance of Ser230 was further established by the S230A HSF1 mutant showing markedly reduced activity relative to wild-type HSF1 when expressed in hsf1(-/-) cells. Our study provides the first evidence that phosphorylation is essential for the transcriptional activity of HSF1, and hence for induction of the heat shock response.

    The EMBO journal 2001;20;14;3800-10

  • Modulation of the G protein regulator phosducin by Ca2+/calmodulin-dependent protein kinase II phosphorylation and 14-3-3 protein binding.

    1f40 Thulin CD, Savage JR, McLaughlin JN, Truscott SM, Old WM, Ahn NG, Resing KA, Hamm HE, Bitensky MW and Willardson BM

    Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA.

    Phototransduction is a canonical G protein-mediated cascade of retinal photoreceptor cells that transforms photons into neural responses. Phosducin (Pd) is a Gbetagamma-binding protein that i 5d3 s highly expressed in photoreceptors. Pd is phosphorylated in dark-adapted retina and is dephosphorylated in response to light. Dephosphorylated Pd binds Gbetagamma with high affinity and inhibits the interaction of Gbetagamma with Galpha or other effectors, whereas phosphorylated Pd does not. These results have led to the hypothesis that Pd down-regulates the light response. Consequently, it is important to understand the mechanisms of regulation of Pd phosphorylation. We have previously shown that phosphorylation of Pd by cAMP-dependent protein kinase moderately inhibits its association with Gbetagamma. In this study, we report that Pd was rapidly phosphorylated by Ca(2+)/calmodulin-dependent kinase II, resulting in 100-fold greater inhibition of Gbetagamma binding than cAMP-dependent protein kinase phosphorylation. Furthermore, Pd phosphorylation by Ca(2+)/calmodulin-dependent kinase II at Ser-54 and Ser-73 led to binding of the phosphoserine-binding protein 14-3-3. Importantly, in vivo decreases in Ca(2+) concentration blocked the interaction of Pd with 14-3-3, indicating that Ca(2+) controls the phosphorylation state of Ser-54 and Ser-73 in vivo. These results are consistent with a role for Pd in Ca(2+)-dependent light adaptation processes in photoreceptor cells and also suggest other possible physiological functions.

    Funded by: NEI NIH HHS: EY06062, EY12287; NIAMS NIH HHS: AR43768

    The Journal of biological chemistry 2001;276;26;23805-15

  • Characterization of a novel synGAP isoform, synGAP-beta.

    Li W, Okano A, Tian QB, Nakayama K, Furihata T, Nawa H and Suzuki T

    Department of Neuroplasticity, Research Center on Aging and Adaptation, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.

    We cloned a cDNA encoding a novel synGAP, synGAP-d (GenBank(TM) accession number ), from a rat brain cDNA library. The clone consisted of 4801 nucleotides with a coding sequence of 3501 nucleotides, encoded a protein consisting of 1166 amino acids with >99% homology with 1092 amino acid overlaps to synGAP, and contained a 13-nucleotide insertion to the previously reported synGAP mRNAs, which suggested that the clone was a splice variant of synGAP. We also found that there are at least seven variants in the 3' portion of the synGAP mRNA and that they encoded five different protein isoforms. The coding sequence of these C-terminal variants were classified into alpha1, alpha2, beta1, beta2, beta3, beta4, and gamma, and synGAP-d was classified as the beta1 form. The previously reported synGAPs (synGAP-a, -b, and -c and p135synGAP) can be classified as the alpha1 isoform. All isoforms were expressed specifically in the brain. Unexpectedly, the beta isoform, which lacks a C-terminal PSD-95-binding motif ((S/T)XV), was more restricted to the postsynaptic density fraction than the motif-containing alpha1 isoform. The beta isoform did not interact with PSD-95 but specifically interacted with a nonphosphorylated alpha subunit of Ca(2+)/calmodulin-dependent protein kinase II through its unique C-terminal tail.

    The Journal of biological chemistry 2001;276;24;21417-24

  • Interaction with the NMDA receptor locks CaMKII in an active conformation.

    Bayer KU, De Koninck P, Leonard AS, JW and Schulman H

    Department of Neurobiology, Stanford University School of Medicine, California 94305-5125, USA. ulli.bayer@stanford.edu

    Calcium- and calmodulin-dependent protein kinase II (CaMKII) and glutamate receptors are integrally involved in forms of synaptic plasticity that may underlie learning and memory. In the simplest model for long-term potentiation, CaMKII is activated by Ca2+ influx through NMDA (N-methyl-D-aspartate) receptors and then potentiates synaptic efficacy by inducing synaptic insertion and increased single-channel conductance of AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors. Here we show that regulated CaMKII interaction with two sites on the NMDA receptor subunit NR2B provides a mechanism for the glutamate-induced translocation of the kinase to the synapse in hippocampal neurons. This interaction can lead to additional forms of potentiation by: facilitated CaMKII response to synaptic Ca2+; suppression of inhibitory autophosphorylation of CaMKII; and, most notably, direct generation of sustained Ca2+/calmodulin (CaM)-independent (autonomous) kinase activity by a mechanism that is independent of the phosphorylation state. Furthermore, the interaction leads to trapping of CaM that may reduce down-regulation of NMDA receptor activity. CaMKII-NR2B interaction may be prototypical for direct activation of a kinase by its targeting protein.

    Nature 2001;411;6839;801-5

  • Evidence for direct protein kinase-C mediated modulation of N-methyl-D-aspartate receptor current.

    Liao GY, Wagner DA, Hsu MH and Leonard JP

    Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.

    Protein kinase-C (PKC) activation differentially affects currents from N-methyl-D-aspartate (NMDA) type glutamate receptors depending upon their subunit composition. Experiments using chimeras initially indicated that the cytoplasmic C-terminal tails of NR2B (responsive to PKC) and NR2C (unresponsive to PKC) subunits contain the amino acid residues responsible for the observed disparity of PKC effects. However, truncation and point mutation experiments have suggested that PKC action on NMDA receptors may be entirely indirect, working via the phosphorylation of associated proteins. Here we suggest that PKC does, in fact, affect NR2B/NR1-011 NMDA currents by direct phosphorylation of the NR2B tail at residues S1303 and S1323. Replacement of either of these residues with Ala severely reduces PKC potentiation. To verify that S1303 and S1323 are sites of direct phosphorylation by PKC, synthetic peptides from the regions surrounding these sites were used as substrates for in vitro assays with purified rat brain PKC. These results indicate that PKC can directly phosphorylate S1303 and S1323 in the NR2B C terminus, leading to enhanced currents through NMDA receptor channels. The direct action of PKC on certain NMDA receptor subtypes may be important in any physiological or pathological process where PKC and NR2B/NR1 receptors interact.

    Funded by: NINDS NIH HHS: R01-NS31962-02

    Molecular pharmacology 2001;59;5;960-4

  • Protein kinase C activation modulates alpha-calmodulin kinase II binding to NR2A subunit of N-methyl-D-aspartate receptor complex.

    Gardoni F, Bellone C, Cattabeni F and Di Luca M

    Institute of Pharmacological Sciences, University of Milano, via Balzaretti 9, 20133 Milano, Italy. fabrizio.gardoni@unimi.it

    The N-methyl-d-aspartate (NMDA) receptor subunits NR2 possess extended intracellular C-terminal domains by which they can directly interact with a large number of postsynaptic density (PSD) proteins involved in synaptic clustering and signaling. We have previously shown that PSD-associated alpha-calmodulin kinase II (alphaCaMKII) binds with high affinity to the C-terminal domain of the NR2A subunit. Here, we show that residues 1412-1419 of the cytosolic tail of NR2A are critical for alphaCaMKII binding, and we identify, by site directed mutagenesis, PKC-dependent phosphorylation of NR2A(Ser(1416)) as a key mechanism in inhibiting alphaCaMKII-binding and promoting dissociation of alphaCaMKII.NR2A complex. In addition, we show that stimulation of PKC activity in hippocampal slices either with phorbol esters or with the mGluRs specific agonist trans-1-amino-1,3- cyclopentanedicarboxylic acid (t-ACPD) decreases alphaCaMKII binding to NMDA receptor complex. Thus, our data provide clues on understanding the molecular basis of a direct cross-talk between alphaCaMKII and PKC pathways in the postsynaptic compartment.

    Funded by: Telethon: 946

    The Journal of biological chemistry 2001;276;10;7609-13

  • Hippocampal synaptic plasticity involves competition between Ca2+/calmodulin-dependent protein kinase II and postsynaptic density 95 for binding to the NR2A subunit of the NMDA receptor.

    Gardoni F, Schrama LH, Kamal A, Gispen WH, Cattabeni F and Di Luca M

    Institute of Pharmacological Sciences, University of Milan, 20133 Milan, Italy. fabrizio.gardoni@unimi.it

    NMDA receptor, Ca(2+)/calmodulin-dependent protein kinase II (alphaCaMKII), and postsynaptic density 95 (PSD-95) are three major components of the PSD fraction. Both alphaCaMKII and PSD-95 have been shown previously to bind NR2 subunits of the NMDA receptor complex. The nature and mechanisms of targeting to the NMDA receptor subunits are, however, not completely understood. Here we report that the C-terminal NR2A(S1389-V1464) sequence was sufficient to guarantee the association of both native and recombinant alphaCaMKII and PSD-95. PSD-95(54-256) was able to compete with the binding of both native and recombinant alphaCaMKII to the NR2A C-tail. Accordingly, alphaCaMKII(1-325) competes with both the native PSD-95 and the native kinase itself for the binding to NR2A. In addition, Ser/Ala1289 and Ser/Asp1289 point mutations on the unique CaMKII phosphosite of NR2A did not significantly influence the binding of native alphaCaMKII and PSD-95 to the NR2A C-tail. Finally, the association-dissociation of alphaCaMKII and PSD-95 to and from the NR2A C-tail was significantly modulated by activation of NMDA receptor achieved by either pharmacological tools or long-term potentiation induction, underlining the importance of dynamic and reciprocal interactions of NMDA receptor, alphaCaMKII, and PSD-95 in hippocampal synaptic plasticity.

    Funded by: Telethon: 946

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2001;21;5;1501-9

  • Molecular cloning and sequence analyses of calcium/calmodulin-dependent protein kinase II from fetal and adult human brain. Sequence analyses of human brain calciuum/calmodulin-dependent protein kinase II.

    Li G, Laabich A, Liu LO, Xue J and Cooper NG

    Department of Anatomical Sciences and Neurobiology University of Louisville School of Medicine, KY 40202, USA.

    The aims of this study were to characterize specific mRNAs and the expression pattern for isoforms of calcium/calmodulin-dependent protein kinase II (CaMKII) in the human brain. We cloned and sequenced the CaMKII alpha and beta subunit cDNAs, and used them to study the CaMKII expression in human brain. Four distinct isoforms of CAMKII were isolated. Two of them were characterized as CaMKII alpha and beta subunits. The other two showed similar nucleotide sequences, but one had a 33-bp insertion relative to the alpha subunit, and the other had a 75-bp deletion relative to the beta subunit. These alterations are located within the variable regions. These two isoforms were characterized as CaMKII alphaB and beta(e). Northern blot analysis showed that a 4.4-kb messenger RNA for the alpha isoform and a 3.9-kb messenger RNA for the beta isoform were expressed in both human fetal and adult brain to different degrees. The results indicate that CaMKII expression is developmentally regulated. The CaMKII isoform expression was confirmed in human fetal and adult brain using RT-PCR with specific primers, which flanked the CaMKII variable regions. The CaMKII alpha, alphaB, beta, beta' and beta(e) isoforms were characterized in both human fetal and adult brain.

    Molecular biology reports 2001;28;1;35-41

  • Calmodulin kinase II attenuation of gene transcription by preventing cAMP response element-binding protein (CREB) dimerization and binding of the CREB-binding protein.

    Wu X and McMurray CT

    Department of Molecular Pharmacology and Experimental Therapeutics, the Mayo Graduate School, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.

    Calmodulin Kinase II (CamKII) inhibits the transcription of many CRE-dependent genes, but the mechanism of dominant transcriptional inhibition is unknown. Here we show that phosphorylation of serine 142 in CREB by CamKII leads to dissociation of the CREB dimer without impeding DNA binding capacity. CamKII-modified CREB binds to DNA efficiently as a monomer; however, monomeric CREB is unable to recruit the CREB-binding protein (CBP) even when phosphorylated at serine 133. Thus, CamKII confers a dominant inhibitory effect on transcription by preventing dimerization of CREB, and this mechanism may account for the attenuation of gene expression.

    Funded by: NIDDK NIH HHS: DK 43694-01A2; NIMH NIH HHS: MH-56207

    The Journal of biological chemistry 2001;276;3;1735-41

  • Densin-180 forms a ternary complex with the (alpha)-subunit of Ca2+/calmodulin-dependent protein kinase II and (alpha)-actinin.

    Walikonis RS, Oguni A, Khorosheva EM, Jeng CJ, Asuncion FJ and Kennedy MB

    Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.

    Densin-180 is a transmembrane protein that is tightly associated with the postsynaptic density in CNS neurons and is postulated to function as a synaptic adhesion molecule. Here we report the identification of the alpha-subunit of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and alpha-actinin-4 as potential binding partners for the densin-180 intracellular segment. We demonstrate by yeast two-hybrid and biochemical assays that the intracellular portion of densin-180, the alpha-subunit of CaMKII (CaMKIIalpha), and alpha-actinin interact with each other at distinct binding sites and can form a ternary complex stabilized by multiple interactions. Densin-180 binds specifically to the association domain of CaMKIIalpha and does not bind with high affinity to holoenzymes of CaMKII that contain beta-subunit. The PDZ (PSD-95, DIg, Z0-1) domain of densin contributes to its binding to alpha-actinin. A distinct domain of alpha-actinin interacts with the kinase domains of both alpha- and beta-subunits of CaMKII. Autophosphorylation of CaMKII increases its affinity for densin-180 from an EC(50) of >1 micrometer to an EC(50) of <75-150 nM. In contrast, phosphorylation of densin-180 by CaMKII at serine-1397 only slightly decreases its affinity for CaMKII. The specific interaction of densin-180 with holoenzymes of CaMKII containing only alpha-subunit and the increased affinity of CaMKII for densin-180 after autophosphorylation suggest that densin-180 may be involved in localization of activated CaMKII synthesized in dendrites.

    Funded by: NINDS NIH HHS: NS17660, NS28710

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2001;21;2;423-33

  • Ca(2+)/CaM-dependent kinases: from activation to function.

    Hook SS and Means AR

    Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA. shook@fhcrc.org

    Calmodulin (CaM) is an essential protein that serves as a ubiquitous intracellular receptor for Ca(2+). The Ca(2+)/CaM complex initiates a plethora of signaling cascades that culminate in alteration of cellular functions. Among the many Ca(2+)/CaM-binding proteins to be discovered, the multifunctional protein kinases CaMKI, II, and IV play pivotal roles. Our review focuses on this class of CaM kinases to illustrate the structural and biochemical basis for Ca(2+)/CaM interaction with and regulation of its target enzymes. Gene transcription has been chosen as the functional endpoint to illustrate the recent advances in Ca(2+)/CaM-mediated signal transduction mechanisms.

    Funded by: NICHD NIH HHS: HD-07503; NIGMS NIH HHS: GM-33976

    Annual review of pharmacology and toxicology 2001;41;471-505

  • Inactivation of smad-transforming growth factor beta signaling by Ca(2+)-calmodulin-dependent protein kinase II.

    Wicks SJ, Lui S, Abdel-Wahab N, Mason RM and Chantry A

    Department of Cancer Medicine, Division of Medicine, Imperial College School of Medicine, Hammersmith Campus, London W12 ONN, United Kingdom.

    Members of the transforming growth factor beta (TGF-beta) family transduce signals through Smad proteins. Smad signaling can be regulated by the Ras/Erk/mitogen-activated protein pathway in response to receptor tyrosine kinase activation and the gamma interferon pathway and also by the functional interaction of Smad2 with Ca(2+)-calmodulin. Here we report that Smad-TGF-beta-dependent transcriptional responses are prevented by expression of a constitutively activated Ca(2+)-calmodulin-dependent protein kinase II (Cam kinase II). Smad2 is a target substrate for Cam kinase II in vitro at serine-110, -240, and -260. Cam kinase II induces in vivo phosphorylation of Smad2 and Smad4 and, to a lesser extent, Smad3. A phosphopeptide antiserum raised against Smad2 phosphoserine-240 reacted with Smad2 in vivo when coexpressed with Cam kinase II and by activation of the platelet-derived growth factor receptor, the epidermal growth factor receptor, HER2 (c-erbB2), and the TGF-beta receptor. Furthermore, Cam kinase II blocked nuclear accumulation of a Smad2 and induced Smad2-Smad4 hetero-oligomerization independently of TGF-beta receptor activation, while preventing TGF-beta-dependent Smad2-Smad3 interactions. These findings provide a novel cross-talk mechanism by which Ca(2+)-dependent kinases activated downstream of multiple growth factor receptors antagonize cell responses to TGF-beta.

    Molecular and cellular biology 2000;20;21;8103-11

  • Inhibition of neuronal nitric-oxide synthase by calcium/ calmodulin-dependent protein kinase IIalpha through Ser847 phosphorylation in NG108-15 neuronal cells.

    Komeima K, Hayashi Y, Naito Y and Watanabe Y

    Departments of Pharmacology and Ophthalmology, Nagoya University School of Medicine, Showa-ku, Nagoya 466-8550, Japan.

    We have previously demonstrated that phosphorylation of neuronal nitric-oxide synthase (nNOS) at Ser(847) by Ca(2+)/calmodulin-dependent protein kinases (CaM kinases) attenuates the catalytic activity of the enzyme in vitro (Hayashi Y., Nishio M., Naito Y., Yokokura H., Nimura Y., Hidaka H., and Watanabe Y. (1999) J. Biol. Chem. 274, 20597-20602). In the present study we determined that CaM kinase IIalpha (CaM-K IIalpha) can directly phosphorylate nNOS on Ser(847), leading to a reduction of nNOS activity in cells. The phosphorylation abilities of purified CaM kinase Ialpha (CaM-K Ialpha), CaM-K IIalpha, and CaM-kinase IV (CaM-K IV) on Ser(847) were analyzed using the synthetic peptide nNOS-(836-859) (Glu-Glu-Arg-Lys-Ser-Tyr-Lys-Val-Arg-Phe-Asn-Ser-Val-Ser-Ser-Tyr-Ser- Asp-Ser-Arg-Lys-Ser-Ser-Gly) from nNOS as substrate. The relative V(max)/K(m) ratios of CaM kinases for nNOS-(836-859) were found to be as follows: CaM-K IIalpha, 100; CaM-K Ialpha, 54.5; CaM-K IV, 9.1. Co-transfection of constitutively active CaM-K IIalpha1-274 but not inactive CaM-K IIalpha1-274, generated by mutation of Lys(42) to Ala, 1f40 with nNOS into NG108-15 cells, resulted in increased Ser(847) phosphorylation in the presence of okadaic acid, an inhibitor of protein phosphatase (PP)1 and PP2A, with a concomitant inhibition of NOS enzyme activity. In addition, this latter decrease could be reversed by treatment with exogenous PP2A. Cells expressing mutant nNOS (S847A) proved resistant to phosphorylation and a decrease of NOS activity. Thus, our results indicate that Ca(2+) triggers cross-talk signal transduction between CaM kinase and NO and CaM-K IIalpha phosphorylating nNOS on Ser(847), which in turn decreases the gaseous second messenger NO in neuronal cells.

    The Journal of biological chemistry 2000;275;36;28139-43

  • Expression, purification and characterization of recombinant human choline acetyltransferase: phosphorylation of the enzyme regulates catalytic activity.

    Dobransky T, Davis WL, Xiao GH and Rylett RJ

    Department of Physiology, Medical Sciences Building, University of Western Ontario, London, Ontario, Canada N6A 5C1.

    Choline acetyltransferase synthesizes acetylcholine in cholinergic neurons and, in humans, may be produced in 82- and 69-kDa forms. In this study, recombinant choline acetyltransferase from baculovirus and bacterial expression systems was used to identify protein isoforms by two-dimensional SDS/PAGE and as substrate for protein kinases. Whereas hexa-histidine-tagged 82- and 69-kDa enzymes did not resolve as individual isoforms on two-dimensional gels, separation of wild-type choline acetyltransferase expressed in insect cells revealed at least nine isoforms for the 69-kDa enzyme and at least six isoforms for the 82-kDa enzyme. Non-phosphorylated wild-type choline acetyltransferase expressed in Escherichia coli yielded six (69 kDa) and four isoforms (82 kDa) respectively. Immunofluorescent labelling of insect cells expressing enzyme showed differential subcellular localization with the 69-kDa enzyme localized adjacent to plasma membrane and the 82-kDa enzyme being cytoplasmic at 24 h. By 64 h, the 69-kDa form was in cytoplasm and the 82-kDa form was only present in nucleus. Studies in vitro showed that recombinant 69-kDa enzyme was a substrate for protein kinase C (PKC), casein kinase II (CK2) and alpha-calcium/calmodulin-dependent protein kinase II (alpha-CaM kinase), but not for cAMP-dependent protein kinase (PKA); phosphorylation by PKC and CK2 enhanced enzyme activity. The 82-kDa enzyme was a substrate for PKC and CK2 but not for PKA or alpha-CaM kinase, with only PKC yielding increased enzyme activity. Dephosphorylation of both forms of enzyme by alkaline phosphatase decreased enzymic activity. These studies are of functional significance as they report for the first time that phosphorylation enhances choline acetyltransferase catalytic activity.

    The Biochemical journal 2000;349;Pt 1;141-51

  • Proteomic analysis of NMDA receptor-adhesion protein signaling complexes.

    Husi H, Ward MA, Choudhary JS, Blackstock WP and Grant SG

    Centre for Genome Research, Centre for Neuroscience, University of Edinburgh, West Mains Road, Edinburgh EH9 3JQ, UK.

    N-methyl-d-aspartate receptors (NMDAR) mediate long-lasting changes in synapse strength via downstream signaling pathways. We report proteomic characterization with mass spectrometry and immunoblotting of NMDAR multiprotein complexes (NRC) isolated from mouse brain. The NRC comprised 77 proteins organized into receptor, adaptor, signaling, cytoskeletal and novel proteins, of which 30 are implicated from binding studies and another 19 participate in NMDAR signaling. NMDAR and metabotropic glutamate receptor subtypes were linked to cadherins and L1 cell-adhesion molecules in complexes lacking AMPA receptors. These neurotransmitter-adhesion receptor complexes were bound to kinases, phosphatases, GTPase-activating proteins and Ras with effectors including MAPK pathway components. Several proteins were encoded by activity-dependent genes. Genetic or pharmacological interference with 15 NRC proteins impairs learning and with 22 proteins alters synaptic plasticity in rodents. Mutations in three human genes (NF1, Rsk-2, L1) are associated with learning impairments, indicating the NRC also participates in human cognition.

    Nature neuroscience 2000;3;7;661-9

  • CaM-kinases: modulators of synaptic plasticity.

    Soderling TR

    Vollum Institute, L-474 Oregon Health Sciences University, Portland, OR 97201, USA. soderlit@ohsu.edu

    Calcium signaling is crucial for several aspects of plasticity at glutamatergic synapses, and studies over the past two to three years have identified key functions for Ca(2+)/calmodulin-dependent protein kinases II and IV (CaM-KII and CaM-KIV). Sustained activation of CaM-KII localized at the postsynaptic density results in phosphorylation of numerous synaptic substrates including ion channels, other signaling molecules and scaffolding proteins, to modulate synaptic transmission within minutes. More prolonged responses may be effected through enhanced dendritic protein synthesis of CaM-KII and regulation of nuclear gene transcription by CaM-KIV.

    Current opinion in neurobiology 2000;10;3;375-80

  • Skeletal muscle CaMKII enriches in nuclei and phosphorylates myogenic factor SRF at multiple sites.

    Flück M, Booth FW and Waxham MN

    Department of Integrative Biology and Pharmacology, University of Texas Medical School, Houston, Texas 77030, USA. flueck@mem.unibe.ch

    We characterized the activity of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) in homogenates and nuclear extracts of skeletal muscle and analyzed their capacity to phosphorylate the myogenic factor SRF. Isoforms of CaMKII enriched from skeletal muscle phosphorylated SRF in vitro to high stoichiometries and produced multiple forms on SDS-PAGE, suggesting that SRF was phosphorylated at multiple sites. Phosphopeptide-mapping experiments using truncated SRF proteins located the residues of SRF phosphorylated by recombinant CaMKII within amino acids 1-171, with at least one site residing in amino acids 142-171. Microsequencing of these phosphorylated peptides identified that both Ser-103 and a novel residue, Thr-160 in the MADS box of SRF, were sites of phosphorylation. CaMKII activity was enriched in nuclear extracts relative to crude homogenates from skeletal muscle and similarly phosphorylated the nuclear transcription factor SRF in vitro. The location of Thr-160 in the 3-D structure of SRF suggests that its phosphorylation by nuclear CaMKII may directly influence DNA binding of SRF and other MADS box factors.

    Funded by: NIAMS NIH HHS: AR19393; NINDS NIH HHS: NS26086

    Biochemical and biophysical research communications 2000;270;2;488-94

  • Phosphorylation sites on tau identified by nanoelectrospray mass spectrometry: differences in vitro between the mitogen-activated protein kinases ERK2, c-Jun N-terminal kinase and P38, and glycogen synthase kinase-3beta.

    Reynolds CH, Betts JC, Blackstock WP, Nebreda AR and Anderton BH

    Department of Neuroscience, Institute of Psychiatry, King's College London, England. h.reynolds@iop.kcl.ac.uk

    The stress-activated kinases c-Jun N-terminal kinase (JNK) and p38 are members of the mitogen-activated protein (MAP) kinase family and take part in signalling cascades initiated by various forms of stress. Their targets include the microtubule-associated protein tau, which becomes hyperphosphorylated in Alzheimer's disease. It is necessary, as a forerunner for in vivo studies, to identify the protein kinases and phosphatases that are responsible for phosphate turnover at individual sites. Using nanoelectrospray mass spectrometry, we have undertaken an extensive comparison of phosphorylation in vitro by several candidate tau kinases, namely, JNK, p38, ERK2, and glycogen synthase kinase 3beta (GSK3beta). Between 10 and 15 sites were identified for each kinase. The three MAP kinases phosphorylated Ser202 and Thr205 but not detectably Ser199, whereas conversely GSK3beta phosphorylated Ser199 but not detectably Ser202 or Thr205. Phosphorylated Ser404 was found with all of these kinases except JNK. The MAP kinases may not be strictly proline specific: p38 phosphorylated the nonproline sites Ser185, Thr245, Ser305, and Ser356, whereas ERK2 was the most strict. All of the sites detected except Thr245 and Ser305 are known or suspected phosphorylation sites in paired helical filament-tau extracted from Alzheimer brains. Thus, the three MAP kinases and GSK3beta are importantly all strong candidates as tau kinases that may be involved in the pathogenic hyperphosphorylation of tau in Alzheimer's disease.

    Journal of neurochemistry 2000;74;4;1587-95

  • Shotgun sequencing of the human transcriptome with ORF expressed sequence tags.

    Dias Neto E, Correa RG, Verjovski-Almeida S, Briones MR, Nagai MA, da Silva W, Zago MA, Bordin S, Costa FF, Goldman GH, Carvalho AF, Matsukuma A, Baia GS, Simpson DH, Brunstein A, de Oliveira PS, Bucher P, Jongeneel CV, O'Hare MJ, Soares F, Brentani RR, Reis LF, de Souza SJ and Simpson AJ

    Ludwig Institute for Cancer Research, São Paulo 01509-010, Brazil.

    Theoretical considerations predict that amplification of expressed gene transcripts by reverse transcription-PCR using arbitrarily chosen primers will result in the preferential amplification of the central portion of the transcript. Systematic, high-throughput sequencing of such products would result in an expressed sequence tag (EST) database consisting of central, generally coding regions of expressed genes. Such a database would add significant value to existing public EST databases, which consist mostly of sequences derived from the extremities of cDNAs, and facilitate the construction of contigs of transcript sequences. We tested our predictions, creating a database of 10,000 sequences from human breast tumors. The data confirmed the central distribution of the sequences, the significant normalization of the sequence population, the frequent extension of contigs composed of existing human ESTs, and the identification of a series of potentially important homologues of known genes. This approach should make a significant contribution to the early identification of important human genes, the deciphering of the draft human genome sequence currently being compiled, and the shotgun sequencing of the human transcriptome.

    Proceedings of the National Academy of Sciences of the United States of America 2000;97;7;3491-6

  • Death-associated protein kinase-related protein 1, a novel serine/threonine kinase involved in apoptosis.

    Inbal B, Shani G, Cohen O, Kissil JL and Kimchi A

    Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.

    In this study we describe the identification and structure-function analysis of a novel death-associated protein (DAP) kinase-related protein, DRP-1. DRP-1 is a 42-kDa Ca(2+)/calmodulin (CaM)-regulated serine threonine kinase which shows high degree of homology to DAP kinase. The region of homology spans the catalytic domain and the CaM-regulatory region, whereas the remaining C-terminal part of the protein differs completely from DAP kinase and displays no homology to any known protein. The catalytic domain is also homologous to the recently identified ZIP kinase and to a lesser extent to the catalytic domains of DRAK1 and -2. Thus, DAP kinase DRP-1, ZIP kinase, and DRAK1/2 together form a novel subfamily of serine/threonine kinases. DRP-1 is localized to the cytoplasm, as shown by immunostaining and cellular fractionation assays. It binds to CaM, undergoes autophosphorylation, and phosphorylates an exogenous substrate, the myosin light chain, in a Ca(2+)/CaM-dependent manner. The truncated protein, deleted of the CaM-regulatory domain, was converted into a constitutively active kinase. Ectopically expressed DRP-1 induced apoptosis in various types of cells. Cell killing by DRP-1 was dependent on two features: the status of the catalytic activity, and the presence of the C-terminal 40 amino acids shown to be required for self-dimerization of the kinase. Interestingly, further deletion of the CaM-regulatory region could override the indispensable role of the C-terminal tail in apoptosis and generated a "superkiller" mutant. A dominant negative fragment of DAP kinase encompassing the death domain was found to block apoptosis induced by DRP-1. Conversely, a catalytically inactive mutant of DRP-1, which functioned in a dominant negative manner, was significantly less effective in blocking cell death induced by DAP kinase. Possible functional connections between DAP kinase and DRP-1 are discussed.

    Molecular and cellular biology 2000;20;3;1044-54

  • Regulation of neuronal nitric-oxide synthase by calmodulin kinases.

    Hayashi Y, Nishio M, Naito Y, Yokokura H, Nimura Y, Hidaka H and Watanabe Y

    Department of Pharmacology, Nagoya University School of Medicine, Showa-ku, Nagoya 466-8550, Japan.

    Phosphorylation of neuronal nitric-oxide synthase (nNOS) by Ca2+/calmodulin (CaM)-dependent protein kinases (CaM kinases) including CaM kinase Ialpha (CaM-K Ialpha), CaM kinase IIalpha (CaM-K IIalpha), and CaM kinase IV (CaM-K IV), was studied. It was found that purified recombinant nNOS was phosphorylated by CaM-K Ialpha, CaM-K IIalpha, and CaM-K IV at Ser847 in vitro. Replacement of Ser847 with Ala (S847A) prevented phosphorylation by CaM kinases. Phosphorylated recombinant wild-type nNOS at Ser847 (approximately 0.5 mol of phosphate incorporation into nNOS) exhibited a 30% decrease of Vmax with little change of both the Km for L-arginine and Kact for CaM relative to unphosphorylated enzyme. The activity of mutant S847D was decreased to a level 50-60% as much as the wild-type enzyme. The decreased NOS enzyme activity of phosphorylated nNOS at Ser847 and mutant S847D was partially due to suppression of CaM binding, but not to impairment of dimer formation which is thought to be essential for enzyme activation. Inactive nNOS lacking CaM-binding ability was generated by mutation of Lys732-Lys-Leu to Asp732-Asp-Glu (Watanabe, Y., Hu, Y., and Hidaka, H. (1997) FEBS Lett. 403, 75-78). It was phosphorylated by CaM kinases, as was the wild-type enzyme, indicating that CaM-nNOS binding was not required for the phosphorylation reaction. We developed antibody NP847, which specifically recognize nNOS in its phosphorylated state at Ser847. Using the antibody NP847, we obtained evidence that nNOS is phosphorylated at Ser847 in rat brain. Thus, our results suggest that CaM kinase-induced phosphorylation of nNOS at Ser847 alters the activity control of this enzyme.

    The Journal of biological chemistry 1999;274;29;20597-602

  • Ras-specific exchange factor GRF: oligomerization through its Dbl homology domain and calcium-dependent activation of Raf.

    Anborgh PH, Qian X, Papageorge AG, Vass WC, DeClue JE and Lowy DR

    Laboratory of Cellular Oncology, National Cancer Institute, Bethesda, Maryland 20892, USA.

    The full-length versions of the Ras-specific exchange factors Ras-GRF1 (GRF1) and Ras-GRF2 (GRF2), which are expressed in brain and a restricted number of other organs, possess an ionomycin-dependent activation of Erk mitogen-activated protein kinase activity in 293T cells (C. L. Farnsworth et al., Nature 376:524-527, 1995; N. P. Fam et al., Mol. Cell. Biol. 17:1396-1406, 1996). Each GRF protein contains a Dbl homology (DH) domain. A yeast two-hybrid screen was used to identify polypeptides that associate with the DH domain of GRF1. In this screen, a positive cDNA clone from a human brain cDNA library was isolated which consisted of the GRF2 DH domain and its adjacent ilimaquinone domain. Deletion analysis verified that the two-hybrid interaction required only the DH domains, and mutation of Leu-263 to Gln (L263Q) in the N terminus of the GRF1 DH domain abolished the two-hybrid interaction, while a cluster of more C-terminally located mutations in the DH domain did not eliminate the interaction. Oligomers between GRF1 and GRF2 were detected in a rat brain extract, and forced expression of GRF1 and GRF2 in cultured mammalian cells formed homo- and hetero-oligomers. Introduction of the L263Q mutation in GRF1 led to a protein that was deficient in oligomer formation, while GRF1 containing the DH cluster mutations formed homo-oligomers with an efficiency similar to that of wild type. Compared to wild-type GRF1, the focus-forming activity on NIH 3T3 cells of the GRF1 DH cluster mutant was reduced, while the L263Q mutant was inactive. Both mutants were impaired in their ability to mediate ionomycin-dependent Erk activity in 293T cells. In the absence of ionomycin, 293T cells expressing wild-type GRF1 contained much higher levels of Ras-GTP than control cells; the increase in Erk activity induced by ionomycin in the GRF1-expressing cells also induced a concomitant increase in Raf kinase activity, but without a further increase in the level Ras-GTP. We conclude that GRF1 and GRF2 can form homo- and hetero-oligomers via their DH domains, that mutational inactivation of oligomer formation by GRF1 is associated with impaired biological and signaling activities, and that in 293T cells GRF1 mediates at least two pathways for Raf activation: one a constitutive signal that is mainly Ras-dependent, and one an ionomycin-induced signal that cooperates with the constitutive signal without further augmenting the level of GTP-Ras.

    Molecular and cellular biology 1999;19;7;4611-22

  • Ca2+/calmodulin-dependent kinase II phosphorylates the epidermal growth factor receptor on multiple sites in the cytoplasmic tail and serine 744 within the kinase domain to regulate signal generation.

    Feinmesser RL, Wicks SJ, Taverner CJ and Chantry A

    Department of Cancer Medicine, Imperial College School of Medicine, Charing Cross Campus, Fulham Palace Road, London W6 8RP, United Kingdom.

    Down-regulation of receptor tyrosine kinase activity plays an essential role in coordinating and controlling cellular growth/differentiation. Ca2+/calmodulin-dependent kinase II (CaM kinase II)-mediated phosphorylation of threonine 1172 in the cytoplasmic tail of HER2/c-erbB2 can modulate tyrosine kinase activity and consensus phosphorylation sites are also found at serines 1046/1047 in the structurally related epidermal growth factor receptor (EGFR). We show that serines 1046/1047 are sites for CaM kinase II phosphorylation, although there is a preference for serine 1047, which resides within the consensus -R-X-X-S-. In addition, we have identified major phosphorylation sites at serine 1142 and serine 1057, which lie within a novel -S-X-D- consensus. Mutation of serines 1046/1047 in full-length EGFR enhanced both fibroblast transformation and tyrosine autokinase activity that was significantly potentiated by additional mutation of serines 1057 and 1142. A single CaM kinase II site was also identified at serine 744 within sub-kinase domain III, and autokinase activity was significantly affected by mutation of this serine to an aspartic acid making this site appear constitutively phosphorylated. We have addressed the mechanism by which CaM kinase II phosphorylation of the EGFR might regulate receptor autokinase activity and show that this modification can hinder association of the cytoplasmic tail with the kinase domain to prevent an enzyme-substrate interaction. We postulate that the location and greater number of CaM kinase II phosphorylation sites in the EGFR compared with HER-2/c-erbB2, leading to differential regulation of autokinase activity, contributes to differences in the strength of downstream signaling events and may explain the higher relative transforming potential of HER-2/cerbB2.

    The Journal of biological chemistry 1999;274;23;16168-73

  • MAPKAP kinase 2 phosphorylates serum response factor in vitro and in vivo.

    Heidenreich O, Neininger A, Schratt G, Zinck R, Cahill MA, Engel K, Kotlyarov A, Kraft R, Kostka S, Gaestel M and Nordheim A

    Institut für Zellbiologie, Abteilung Molekularbiologie, Universität Tübingen, D-72076 Tübingen, Germany.

    Several growth factor- and calcium-regulated kinases such as pp90(rsk) or CaM kinase IV can phosphorylate the transcription factor serum response factor (SRF) at serine 103 (Ser-103). However, it is unknown whether stress-regulated kinases can also phosphorylate SRF. We show that treatment of cells with anisomycin, arsenite, sodium fluoride, or tetrafluoroaluminate induces phosphorylation of SRF at Ser-103 in both HeLa and NIH3T3 cells. This phosphorylation is dependent on the kinase p38/SAPK2 and correlates with the activation of MAPKAP kinase 2 (MK2). MK2 phosphorylates SRF in vitro at Ser-103 with similar efficiency as the small heat shock protein Hsp25 and significantly better than CREB. Comparison of wild type murine fibroblasts with those derived from MK2-deficient mice (Mk(-/-)) reveals MK2 as the major SRF kinase induced by arsenite. These results demonstrate that SRF is targeted by several signal transduction pathways within cells and establishes SRF as a nuclear target for MAPKAP kinase 2.

    The Journal of biological chemistry 1999;274;20;14434-43

  • Phosphorylation that detaches tau protein from microtubules (Ser262, Ser214) also protects it against aggregation into Alzheimer paired helical filaments.

    Schneider A, Biernat J, von Bergen M, Mandelkow E and Mandelkow EM

    Max-Planck-Unit for Structural Molecular Biology, Notkestrasse 85, D-22603 Hamburg, Germany.

    One of the hallmarks of Alzheimer's disease is the abnormal state of the microtubule-associated protein tau in neurons. It is both highly phosphorylated and aggregated into paired helical filaments, and it is commonly assumed that the hyperphosphorylation of tau causes its detachment from microtubules and promotes its assembly into PHFs. We have studied the relationship between the phosphorylation of tau by several kinases (MARK, PKA, MAPK, GSK3) and its assembly into PHFs. The proline-directed kinases MAPK and GSK3 are known to phosphorylate most Ser-Pro or Thr-Pro motifs in the regions flanking the repeat domain of tau: they induce the reaction with several antibodies diagnostic of Alzheimer PHFs, but this type of phosphorylation has only a weak effect on tau-microtubule interactions and on PHF assembly. By contrast, MARK and PKA phosphorylate several sites within the repeats (notably the KXGS motifs including Ser262, Ser324, and Ser356, plus Ser320); in addition PKA phosphorylates some sites in the flanking domains, notably Ser214. This type of phosphorylation strongly reduces tau's affinity for microtubules, and at the same time inhibits tau's assembly into PHFs. Thus, contrary to expectations, the phosphorylation that detaches tau from microtubules does not prime it for PHF assembly, but rather inhibits it. Likewise, although the phosphorylation sites on Ser-Pro or Thr-Pro motifs are the most prominent ones on Alzheimer PHFs (by antibody labeling), they are only weakly inhibitory to PHF assembly. This implies that the hyperphosphorylation of tau in Alzheimer's disease is not directly responsible for the pathological aggregation into PHFs; on the contrary, phosphorylation protects tau against aggregation.

    Biochemistry 1999;38;12;3549-58

  • Prediction of the coding sequences of unidentified human genes. XIII. The complete sequences of 100 new cDNA clones from brain which code for large proteins in vitro.

    Nagase T, Ishikawa K, Suyama M, Kikuno R, Hirosawa M, Miyajima N, Tanaka A, Kotani H, Nomura N and Ohara O

    Kazusa DNA Research Institute, Kisarazu, Chiba, Japan.

    As a part of our cDNA project for deducing the coding sequence of unidentified human genes, we newly determined the sequences of 100 cDNA clones from a set of size-fractionated human brain cDNA libraries, and predicted the coding sequences of the corresponding genes, named KIAA0919 to KIAA1018. The sequencing of these clones revealed that the average sizes of the inserts and corresponding open reading frames were 4.9 kb and 2.6 kb (882 amino acid residues), respectively. A computer search of the sequences against the public databases indicated that predicted coding sequences of 87 genes contained sequences similar to known genes, 53% of which (46 genes) were categorized as proteins relating to cell signaling/communication, cell structure/motility and nucleic acid management. The chromosomal locations of the genes were determined by using human-rodent hybrid panels unless their mapping data were already available in the public databases. The expression profiles of all the genes among 10 human tissues, 8 brain regions (amygdala, corpus callosum, cerebellum, caudate nucleus, hippocampus, substania nigra, subthalamic nucleus, and thalamus), spinal cord, fetal brain and fetal liver were also examined by reverse transcription-coupled polymerase chain reaction, products of which were quantified by enzyme-linked immunosorbent assay.

    DNA research : an international journal for rapid publication of reports on genes and genomes 1999;6;1;63-70

  • New phosphorylation sites identified in hyperphosphorylated tau (paired helical filament-tau) from Alzheimer's disease brain using nanoelectrospray mass spectrometry.

    Hanger DP, Betts JC, Loviny TL, Blackstock WP and Anderton BH

    Department of Neuroscience, Institute of Psychiatry, London, England, UK.

    Paired helical filaments (PHFs) are the structural constituents of neurofibrillary tangles in Alzheimer's disease and are composed of hyperphosphorylated forms of the microtubule-associated protein tau (PHF-tau). Pathological hyperphosphorylation of tau is believed to be an important contributor to the destabilisation of microtubules and their subsequent disappearance from tangle-bearing neurons in Alzheimer's disease, making elucidation of the mechanisms that regulate tau phosphorylation an important research goal. Thus, it is essential to identify, preferably by direct sequencing, all of the sites in PHF-tau that are phosphorylated, a task that is incomplete because of the difficulty to date of purifying insoluble PHF-tau to homogeneity and in sufficient quantities for structural analysis. Here we describe the solubilisation of PHF-tau followed by its purification by Mono Q chromatography and reversed-phase HPLC. Phosphopeptides from proteolytically digested PHF-tau were sequenced by nanoelectrospray mass spectrometry. We identified 22 phosphorylation sites in PHF-tau, including five sites not previously identified. The combination of our new data with previous reports shows that PHF-tau can be phosphorylated on at least 25 different sites.

    Funded by: Wellcome Trust

    Journal of neurochemistry 1998;71;6;2465-76

  • Calcium/calmodulin-dependent protein kinase II controls integrin alpha5beta1-mediated cell adhesion through the integrin cytoplasmic domain associated protein-1alpha.

    Bouvard D and Block MR

    Faculté de Médecine de Grenoble, UMR CNRS/UJF 5538, and, La Tronche Cedex, F38706, France.

    This paper provided evidence that the regulation of CHO cell adhesion on fibronectin by calcium/calmodulin-dependent protein kinase II (CaMKII) is mediated through the recently described integrin cytoplasmic domain associated protein-1alpha (ICAP-1alpha). The point mutation T38D localized within the optimal CaMKII recognition motif of ICAP-1alpha results in a strong defect in cell spreading which cannot be overcome by the inhibition of the endogenous CaMKII. This fact strongly suggests that the phosphorylation of Threonine 38 by CaMKII modulates the alpha5beta1 integrin function. Conversely, the mutation T38A produces an analog of ICAP-1alpha that cannot be phosphorylated and that stimulates cell spreading on fibronectin to a similar extent when CaMKII is inhibited.

    Biochemical and biophysical research communications 1998;252;1;46-50

  • Tau is phosphorylated by GSK-3 at several sites found in Alzheimer disease and its biological activity markedly inhibited only after it is prephosphorylated by A-kinase.

    Wang JZ, Wu Q, Smith A, Grundke-Iqbal I and Iqbal K

    Chemical Neuropathology Department, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314-6399, USA.

    Alzheimer disease is characterized by a specific type of neuronal degeneration in which the microtubule associated protein tau is abnormally hyperphosphorylated causing the disruption of the microtubule network. We have found that the phosphorylation of human tau (tau3L) by A-kinase, GSK-3 or CK-1 inhibits its microtubule assembly-promoting and microtubule-binding activities. However, the inhibition of these activities of tau by GSK-3 is significantly increased if tau is prephosphorylated by A-kinase or CK-1. The most potent inhibition is observed by combination phosphorylation of tau with A-kinase and GSK-3. Under these conditions, only very few microtubules are seen by electron microscopy. Sequencing of 32P-labeled trypsin phosphopeptides from tau prephosphorylated by A-kinase (using unlabeled ATP) and further phosphorylated by GSK-3 in the presence of [gamma-32P]ATP revealed that Ser-195, Ser-198, Ser-199, Ser-202, Thr-205, Thr-231, Ser-235, Ser-262, Ser-356 and Ser-404 are phosphorylated, whereas if tau is not prephosphorylated by A-kinase, GSK-3 phosphorylates it at Thr-181, Ser-184, Ser-262, Ser-356 and Ser-400. These data suggest that (i) prephosphorylation of tau by A-kinase makes additional and different sites accessible for phosphorylation by GSK-3; (ii) phosphorylation of tau at these additional sites further inhibits the biological activity of tau in its ability to bind to microtubules and promote microtubule assembly. Thus a combined role of A-kinase and GSK-3 should be considered in Alzheimer neurofibrillary degeneration.

    Funded by: NIA NIH HHS: AG05892, AG08076; NINDS NIH HHS: NS18105; ...

    FEBS letters 1998;436;1;28-34

  • Phosphorylation of tau at both Thr 231 and Ser 262 is required for maximal inhibition of its binding to microtubules.

    Sengupta A, Kabat J, Novak M, Wu Q, Grundke-Iqbal I and Iqbal K

    New York State Institute for Basic Research in Developmental Disabilities, Staten Island 10314, USA. kiqbal@admin.con2.com

    The paired helical filaments (PHFs) found in Alzheimer's disease (AD) brains are composed primarily of the microtubule-associated protein tau. PHF-tau is in a hyperphosphorylated state and is unable to promote microtubule assembly. We investigated whether the inhibition of tau binding to microtubules is increased when tau is phosphorylated by different kinases in combination with GSK-3. We found that when tau was first phosphorylated by A-kinase, C-kinase, cdk5, or CaM kinase II and then by GSK-3, its binding to microtubules was inhibited by 45, 61, 78, and 79%, respectively. Further, the kinase combinations cdk5/GSK-3 and CaM kinase II/GSK-3 rapidly phosphorylated the sites Thr 231 and Ser 235. When these sites were individually replaced by Ala and the phosphorylation experiments repeated, tau binding to microtubules was inhibited by 54 and 71%, respectively. By comparison, when Ser 262 was replaced by Ala, tau binding to microtubules was inhibited by only 8% after phosphorylation by CaM kinase II. From these observations we estimate that the phosphorylation of Thr 231, Ser 235, and Ser 262 contributes approximately 26, approximately 9, and approximately 33%, respectively, of the overall inhibition of tau binding to microtubules. Together, our results indicate that the binding of tau to microtubules is controlled by the phosphorylation of several sites, among which are Thr 231, Ser 235, and Ser 262.

    Funded by: NIA NIH HHS: AG05892, AG08076; NINDS NIH HHS: NS18105

    Archives of biochemistry and biophysics 1998;357;2;299-309

  • Characterization of a calmodulin kinase II inhibitor protein in brain.

    Chang BH, Mukherji S and Soderling TR

    Vollum Institute, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97201, USA.

    Ca2+/calmodulin-dependent protein kinase II (CaM-KII) regulates numerous physiological functions, including neuronal synaptic plasticity through the phosphorylation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptors. To identify proteins that may interact with and modulate CaM-KII function, a yeast two-hybrid screen was performed by using a rat brain cDNA library. This screen identified a unique clone of 1.4 kb, which encoded a 79-aa brain-specific protein that bound the catalytic domain of CaM-KII alpha and beta and potently inhibited kinase activity with an IC50 of 50 nM. The inhibitory protein (CaM-KIIN), and a 28-residue peptide derived from it (CaM-KIINtide), was highly selective for inhibition of CaM-KII with little effect on CaM-KI, CaM-KIV, CaM-KK, protein kinase A, or protein kinase C. CaM-KIIN interacted only with activated CaM-KII (i. e., in the presence of Ca2+/CaM or after autophosphorylation) by using glutathione S-transferase/CaM-KIIN precipitations as well as coimmunoprecipitations from rat brain extracts or from HEK293 cells cotransfected with both constructs. Colocalization of CaM-KIIN with activated CaM-KII was demonstrated in COS-7 cells transfected with green fluorescent protein fused to CaM-KIIN. In COS-7 cells phosphorylation of transfected alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptors by CaM-KII, but not by protein kinase C, was blocked upon cotransfection with CaM-KIIN. These results characterize a potent and specific cellular inhibitor of CaM-KII that may have an important role in the physiological regulation of this key protein kinase.

    Funded by: NIGMS NIH HHS: GM41292, R01 GM041292; NINDS NIH HHS: NS07381, T32 NS007381

    Proceedings of the National Academy of Sciences of the United States of America 1998;95;18;10890-5

  • Abnormal hippocampal spatial representations in alphaCaMKIIT286A and CREBalphaDelta- mice.

    Cho YH, Giese KP, Tanila H, Silva AJ and Eichenbaum H

    Department of Psychology, Boston University, Boston, MA 02215, USA.

    Hippocampal "place cells" fire selectively when an animal is in a specific location. The fine-tuning and stability of place cell firing was compared in two types of mutant mice with different long-term potentiation (LTP) and place learning impairments. Place cells from both mutants showed decreased spatial selectivity. Place cell stability was also deficient in both mutants and, consistent with the severities in their LTP and spatial learning deficits, was more affected in mice with a point mutation [threonine (T) at position 286 mutated to alanine (A)] in the alpha calmodulin kinase II (alphaCaMKIIT286A) than in mice deficient for the alpha and Delta isoforms of adenosine 3'5'-monophosphate-responsive element binding proteins (CREBalphaDelta-). Thus, LTP appears to be important for the fine tuning and stabilization of place cells, and these place cell properties may be necessary for spatial learning.

    Funded by: NIA NIH HHS: AG13622; NIMH NIH HHS: MH51570

    Science (New York, N.Y.) 1998;279;5352;867-9

  • Autophosphorylation at Thr286 of the alpha calcium-calmodulin kinase II in LTP and learning.

    Giese KP, Fedorov NB, Filipkowski RK and Silva AJ

    Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.

    The calcium-calmodulin-dependent kinase II (CaMKII) is required for hippocampal long-term potentiation (LTP) and spatial learning. In addition to its calcium-calmodulin (CaM)-dependent activity, CaMKII can undergo autophosphorylation, resulting in CaM-independent activity. A point mutation was introduced into the alphaCaMKII gene that blocked the autophosphorylation of threonine at position 286 (Thr286) of this kinase without affecting its CaM-dependent activity. The mutant mice had no N-methyl-D-aspartate receptor-dependent LTP in the hippocampal CA1 area and showed no spatial learning in the Morris water maze. Thus, the autophosphorylation of alphaCaMKII at Thr286 appears to be required for LTP and learning.

    Funded by: NIA NIH HHS: AG13622

    Science (New York, N.Y.) 1998;279;5352;870-3

  • Adjacent asparagines in the NR2-subunit of the NMDA receptor channel control the voltage-dependent block by extracellular Mg2+.

    Wollmuth LP, Kuner T and Sakmann B

    Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung, Heidelberg, Germany. wollmuth@sunny.mpimf-Heidelberg.mpg.de

    1. The voltage-dependent block of N-methyl-D-aspartate (NMDA) receptor channels by extracellular Mg2+ is a critical determinant of its contribution to CNS synaptic physiology. The function of the narrow constriction of the channel in determining the block was investigated by analysing the effects of a set different amino acid substitutions at exposed residues positioned at or near this region. NMDA receptor channels, composed of wild-type and mutant NR1- and NR2A-subunits, were expressed in Xenopus oocytes or human embryonic kidney (HEK) 293 cells. 2. In wild-type channels, the voltage dependence (delta) of the block Mg2+ was concentration dependent with values of delta of integral of 0.82 in 0.07 mM and higher concentrations. Under bionic conditions with high extracellular Mg2+ and K+ as the reference ion, Mg2+ weakly permeated the channel. Over intermediate potentials (approximately -60 to -10 mV), this weak permeability had no apparent effect on the block but at potentials negative to approximately -60mV, it attenuated the extent and voltage dependence of the block. 3. Substitutions of glycine, serine, glutamine or aspartate for the N-site asparagine in the NR1-subunit enhanced the extent of block over intermediate potentials but left the voltage dependence of the block unchanged indicating that structural determinants of the block remained. These same substitutions either attenuated or left unchanged the apparent Mg2+ permeability. 4. In channels containing substitutions of glycine, serine or glutamine for the N-site asparagine in the NR2A-subunit, the block Mg2+ was reduced at negative potentials. Over intermediate potentials, the block was not strongly attenuated except for the glutamine substitution which reduced the voltage dependence of the block to integral of 0.57 in 0.7 mM Mg2+. 5. Equivalent substitutions for the N + 1 site asparagine in the NR2A-subunit strongly attenuated the block over the entire voltage range. In 0.7 mM Mg2+, the voltage dependence of the block was reduced to 0.50 (glycine), 0.53 (serine) and 0.46 (glutamine). 6. Channels containing substitutions of the N-site or N + 1 site asparagines in the NR2A-subunit showed an increased Mg2+ permeability suggesting that these adjacent asparagines form a barrier for inward Mg2+ flux. Changes in this barrier contribute, at least in part, to the mechanism underlying disruption of the block following substitution of these residues. 7. The adjacent NR2A-subunit asparagines are positioned at or near the narrow constriction of the channel. Pore size, however, did not determine how effectively Mg2+ blocks mutant channels. 8. It is concluded that, at the narrow constriction in the NMDA receptor channel, the adjacent NR2A-subunit asparagines, the N-site and N + 1 site, but not the N-site asparagine of the NR1-subunit, form a critical blocking site for extracellular Mg2+. The contribution to the blocking site, in contrast to the prevailing view, is stronger for the N + 1 site than for the N-site asparagine. The block may involve binding of Mg2+ to these residues.

    The Journal of physiology 1998;506 ( Pt 1);13-32

  • Rad and Rad-related GTPases interact with calmodulin and calmodulin-dependent protein kinase II.

    Moyers JS, Bilan PJ, Zhu J and Kahn CR

    Research Division, Joslin Diabetes Center, and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA.

    Members of the Rad family of GTPases (including Rad, Gem, and Kir) possess several unique features of unknown function in comparison to other Ras-like proteins, with major N-terminal and C-terminal extensions, a lack of typical prenylation motifs, and several non-conservative changes in the sequence of the GTP binding domain. Here we show that Rad and Gem bind to calmodulin (CaM)-Sepharose in vitro in a calcium-dependent manner and that Rad can be co-immunoprecipitated with CaM in C2C12 cells. The interaction is influenced by the guanine nucleotide binding state of Rad with the GDP-bound form exhibiting 5-fold better binding to CaM than the GTP-bound protein. In addition, the dominant negative mutant of Rad (S105N) which binds GDP, but not GTP, exhibits enhanced binding to CaM in vivo when expressed in C2C12 cells. Peptide competition studies and expression of deletion mutants of Rad localize the binding site for CaM to residues 278-297 at the C terminus of Rad. This domain contains a motif characteristic of a calmodulin-binding region, consisting of numerous basic and hydrophobic residues. In addition, we have identified a second potential regulatory domain in the extended N terminus of Rad which, when removed, decreases Rad protein expression but increases the binding of Rad to CaM. The ability of Rad mutants to bind CaM correlates with their localization in cytoskeletal fractions of C2C12 cells. Immunoprecipitates of calmodulin-dependent protein kinase II, the cellular effector of Ca2+-calmodulin, also contain Rad, and in vitro both Rad and Gem can serve as substrates for this kinase. Thus, the Rad family of GTP-binding proteins possess unique characteristics of binding CaM and calmodulin-dependent protein kinase II, suggesting a role for Rad-like GTPases in calcium activation of serine/threonine kinase cascades.

    Funded by: NIDDK NIH HHS: DK 07260, DK 45935, P30DK36836

    The Journal of biological chemistry 1997;272;18;11832-9

  • Phosphorylation of glial fibrillary acidic protein at the same sites by cleavage furrow kinase and Rho-associated kinase.

    Kosako H, Amano M, Yanagida M, Tanabe K, Nishi Y, Kaibuchi K and Inagaki M

    Laboratory of Biochemistry, Aichi Cancer Center Research Institute, Chikusa-ku, Nagoya, Aichi 464, Japan.

    Site- and phosphorylation state-specific antibodies are useful to analyze spatiotemporal distribution of site-specific phosphorylation of target proteins in vivo. Using several polyclonal and monoclonal antibodies that can specifically recognize four phosphorylated sites on glial fibrillary acidic protein (GFAP), we have previously reported that Thr-7, Ser-13, and Ser-34 on this intermediate filament protein are phosphorylated at the cleavage furrow during cytokinesis. This observation suggests that there exists a protein kinase named cleavage furrow kinase specifically activated at metaphase-anaphase transition (Matsuoka, Y., Nishizawa, K., Yano, T., Shibata, M., Ando, S., Takahashi, T., and Inagaki, M. (1992) EMBO J. 11, 2895-2902; Sekimata, M., Tsujimura, K., Tanaka, J., Takeuchi, Y., Inagaki, N., and Inagaki, M. (1996) J. Cell Biol. 132, 635-641). Here we report that GFAP is phosphorylated specifically at Thr-7, Ser-13, and Ser-34 by Rho-associated kinase (Rho-kinase), which binds to the small GTPase Rho in its GTP-bound active form. The kinase activity of Rho-kinase toward GFAP is dramatically stimulated by guanosine 5'-(3-O-thio)-triphosphate-bound RhoA. Furthermore, the phosphorylation of GFAP by Rho-kinase results in a nearly complete inhibition of its filament formation in vitro. The possibility that Rho-kinase is a candidate for cleavage furrow kinase is discussed.

    The Journal of biological chemistry 1997;272;16;10333-6

  • The regulatory Ser262 of microtubule-associated protein tau is phosphorylated by phosphorylase kinase.

    Paudel HK

    Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, H3T 1E2, Canada.

    Abnormally phosphorylated tau is the major component of paired helical filaments found in the brains of patients suffering from Alzheimer's disease. Therefore, the identification of kinases that phosphorylate tau is of considerable interest. A DEAE-Sepharose column resolved porcine brain extract into five tau kinase activity peaks. Among these peaks, two were completely inhibited by EGTA, indicating that these two activity peaks contained Ca2+-dependent tau kinases. One of the above two Ca2+-dependent tau kinase activity peaks also contained phosphorylase kinase activity. The tau kinase and phosphorylase kinase activities associated with this peak could not be separated from each other by Superose 12 gel filtration, hydroxylapatite, and calmodulin-agarose affinity chromatographies. Phosphorylase kinase, purified from rabbit skeletal muscle, phosphorylated tau to a stoichiometry of 2.1 mol of phosphate/mol of tau and converted tau to a species with a retarded mobility on SDS-polyacrylamide gel electrophoresis. The apparent Km and kcat values for tau phosphorylation by muscle phosphorylase kinase were 6.9 microM and 47.4 min-1, respectively. As a substrate of muscle phosphorylase kinase, phosphorylase was eight times better than tau. Sequence analyses of tryptic and thermolytic phosphopeptides derived from tau phosphorylated by muscle phosphorylase kinase revealed five phosphorylation sites, Ser237, Ser262, Ser285, Ser305, and Ser352. Among these sites, Ser262 was previously shown to be phosphorylated in human tau from fetal, adult, and Alzheimer's diseased brains (Seubert, P., Mawal-Dewan, M., Barbour, R., Jakes, R., Goedert, M., Johnson, G. V. W., Litersky, J. M., Schenk, D., Lieberburg, I., Trojanowski, J. Q., and Lee, V. M. Y. (1995) J. Biol. Chem. 270, 18917-18922); and its phosphorylation abolished tau's binding to microtubules (Drewes, G., Trinczek, B., Illenberger, S., Biernat, J., Schmitt-Ulms, G., Meyer, H. E., Mandelkow, E.-M., and Mandelkow, E. (1995) J. Biol. Chem. 270, 7679-7688). Slot-blot analysis using a monoclonal antibody against muscle phosphorylase kinase and an activity assay using phosphorylase revealed that phosphorylase kinase was present in microtubules extensively purified by repeated cycles of polymerization and depolymerization. Taken together, these results suggest that in neurons, phosphorylase kinase may be one of the kinases that participate in the phosphorylation of tau.

    The Journal of biological chemistry 1997;272;3;1777-85

  • Mice expressing activated CaMKII lack low frequency LTP and do not form stable place cells in the CA1 region of the hippocampus.

    Rotenberg A, Mayford M, Hawkins RD, Kandel ER and Muller RU

    SUNY Downstate Medical Center, Department of Physiology, Brooklyn, New York 11203, USA.

    To relate different forms of synaptic plasticity to the formation and maintenance of place cells in the hippocampus, we have recorded place cells in freely behaving, transgenic mice that express a mutated Ca2+-independent form of CaM Kinase II. These mice have normal long-term potentiation (LTP) at 100 Hz, but they lack LTP in response to stimulation at 5-10 Hz and are impaired on spatial memory tasks. In these transgenic mice, the place cells in the CA1 region have three important differences from those of wild types: they are less common, less precise, and less stable. These findings suggest that LTP in the 5-10 Hz range may be important for the maintenance of place-field stability and that this stability may be essential for the storage of spatial memory.

    Cell 1996;87;7;1351-61

  • Identification of a phosphorylation site for calcium/calmodulindependent protein kinase II in the NR2B subunit of the N-methyl-D-aspartate receptor.

    Omkumar RV, Kiely MJ, Rosenstein AJ, Min KT and Kennedy MB

    Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.

    The N-methyl-D-aspartate (NMDA) subtype of excitatory glutamate receptors plays critical roles in embryonic and adult synaptic plasticity in the central nervous system. The receptor is a heteromultimer of core subunits, NR1, and one or more regulatory subunits, NR2A-D. Protein phosphorylation can regulate NMDA receptor function (Lieberman, D. N., and Mody, I. (1994) Nature 369, 235-239; Wang, Y. T., and Salter, M. W. (1994) Nature 369, 233-235; Wang, L. -Y., Orser, B. A., Brautigan, D. L., and MacDonald, J. F. (1994) Nature 369, 230-232). Here we identify a major phosphorylation site on subunit NR2B that is phosphorylated by Ca2+/calmodulin-dependent protein kinase II (CaM kinase II), an abundant protein kinase located at postsynaptic sites in glutamatergic synapses. For the initial identification of the site, we constructed a recombinant fusion protein containing 334 amino acids of the C terminus of the NR2B subunit and phosphorylated it with CaM kinase II in vitro. By peptide mapping, automated sequencing, and mass spectrometry, we identified the major site of phosphorylation on the fusion protein as Ser-383, corresponding to Ser-1303 of full-length NR2B. The Km for phosphorylation of this site in the fusion protein was approximately 50 nM, much lower than that of other known substrates for CaM kinase II, suggesting that the receptor is a high affinity substrate. We show that serine 1303 in the full-length NR2B and/or the cognate site in NR2A is a major site of phosphorylation of the receptor both in the postsynaptic density fraction and in living hippocampal neurons.

    Funded by: NIMH NIH HHS: MH49176; NINDS NIH HHS: NS17660, NS28710

    The Journal of biological chemistry 1996;271;49;31670-8

  • Calmodulin-dependent protein kinase II potentiates transcriptional activation through activating transcription factor 1 but not cAMP response element-binding protein.

    Shimomura A, Ogawa Y, Kitani T, Fujisawa H and Hagiwara M

    Department of Anatomy, Nagoya University School of Medicine, Japan.

    Activating transcription factor 1 (ATF1) and the cAMP response element-binding protein (CREB) are members of the CREB/ATF family implicated in cAMP- and calcium-induced transcriptional activation. Although ATF1 and CREB share extensive homology, the function of ATF1 is poorly understood. Its phosphorylation state and activation by Ca2+- and calmodulin-dependent protein kinase (CaMK) II were therefore examined. Phosphopeptide mapping analysis and Western blotting studies demonstrated that in vitro, CaMK II phosphorylates only Ser63 (corresponding to Ser133 of CREB), which is essential for the activation, and not Ser72 (corresponding to Ser142 of CREB), which is a negative regulation site. Both ATF1 and CREB bound CBP in a phosphorylation-dependent manner. As expected from these in vitro studies, transient transfection studies revealed that ATF1 is activated by CaMK II. Our findings suggest that CaMK II mediates transactivation of cAMP responsive genes via ATF1.

    The Journal of biological chemistry 1996;271;30;17957-60

  • Expression of Ca2+/calmodulin-dependent protein kinase types II and IV, and reduced DNA synthesis due to the Ca2+/calmodulin-dependent protein kinase inhibitor KN-62 (1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenyl piperazine) in small cell lung carcinoma.

    Williams CL, Phelps SH and Porter RA

    Molecular Pharmacology Laboratory, Guthrie Research Institute, Sayre, PA 18840, USA.

    Because changes in intracellular Ca2+ affect progression through the mitotic cell cycle, we investigated the role of Ca2+-binding proteins in regulating cell cycle progression. Evidence was found demonstrating that the activation of Ca2+/calmodulin-dependent protein kinase (CaM kinase) inhibits cell cycle progression in small cell lung carcinoma (SCLC) cells. We also demonstrated that SCLC cells express both CaM kinase type II (CaMKII) and CaM kinase type IV (CaMKIV). Five independent SCLC cell lines expressed proteins reactive with antibody to the CaMKII beta subunit, but none expressed detectable proteins reactive with antibody to the CaMKII alpha subunit. All SCLC cell lines tested expressed both the alpha and beta isoforms of CaMKIV. Immunoprecipitation of CaMKII from SCLC cells yielded multiple proteins that autophosphorylated in the presence of Ca2+ / calmodulin. Autophosphorylation was inhibited by the CaMKII(281-302) peptide, which corresponds to the CaMKII autoinhibitory domain, and by 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4- phenylpiperazine (KN-62), a specific CaM kinase antagonist. Influx of Ca2+ through voltage-gated Ca2+ channels stimulated phosphorylation of CaMKII in SCLC cells, and this was inhibited by KN-62. Incubation of SCLC cells of KN-62 potently inhibited DNA synthesis, and slowed progression through S phase. Similar anti-proliferative effects of KN-62 occurred in SK-N-SH human neuroblastoma cells, which express both CaMKII and CaMKIV, and in K562 human chronic myelogenous leukemia cells, which express CaMKII but not CaMKIV. The expression of both CaMKII and CaMKIV by SCLC cells, and the sensitivity of these cells to the anti-proliferative effects of KN-62, suggest a role for CaM kinase in regulating SCLC proliferation.

    Funded by: NCI NIH HHS: CA52471

    Biochemical pharmacology 1996;51;5;707-15

  • Developmental rearrangements of cortical glutamate-NMDA receptor binding sites in late human gestation.

    Andersen DL, Tannenberg AE, Burke CJ and Dodd PR

    Royal Brisbane Hospital Research Foundation, Australia.

    NMDA-preferring glutamate receptor biding sites were characterized using the site-selective ligand [3H]MK801, in synaptic membranes prepared from cerebral cortex tissue obtained postmortem from human infants who had died with minimal neurological and neuropathological impairment between 22 and 42 weeks' gestation. It proved necessary to modify the assay protocol used with adult tissue before reliable data could be obtained. In the four cortical region studied (prefrontal, motor, occipital, temporal), [3H]MK801 bound to a single class of sites which showed significant variations in affinity only in motor cortex. The density of [3H]MK801 binding sites (calculated at constant affinity) showed marked increases in all cortical regions over this period. The extent to which glutamate could enhance [3H]MK801 binding became significantly lower in prefrontal and motor cortex as gestation progressed, so that at term, little activation was apparent. In occipital and temporal cortex, this parameter was low throughout late gestation. The evidence suggests that Glutamate-NMDA binding sites may undergo structural rearrangements which alter their ability to interact with ligands during the later stages of human gestation, and that such changes are regionally variable.

    Brain research. Developmental brain research 1995;88;2;178-85

  • Microtubule-associated protein/microtubule affinity-regulating kinase (p110mark). A novel protein kinase that regulates tau-microtubule interactions and dynamic instability by phosphorylation at the Alzheimer-specific site serine 262.

    Drewes G, Trinczek B, Illenberger S, Biernat J, Schmitt-Ulms G, Meyer HE, Mandelkow EM and Mandelkow E

    Max-Planck Unit for Structural Molecular Biology, Hamburg, Federal Republic of Germany.

    Aberrant phosphorylation of the microtubule-associated protein tau is one of the pathological features of neuronal degeneration in Alzheimer's disease. The phosphorylation of Ser-262 within the microtubule binding region of tau is of particular interest because so far it is observed only in Alzheimer's disease (Hasegawa, M., Morishima-Kawashima, M., Takio, K., Suzuki, M., Titani, K., and Ihara, Y. (1992) J. Biol. Chem. 26, 17047-17054) and because phosphorylation of this site alone dramatically reduces the affinity for microtubules in vitro (Biernat, J., Gustke, N., Drewes, G., Mandelkow, E.-M., and Mandelkow, E. (1993) Neuron 11, 153-163). Here we describe the purification and characterization of a protein-serine kinase from brain tissue with an apparent molecular mass of 110 kDa on SDS gels. This kinase specifically phosphorylates tau on its KIGS or KCGS motifs in the repeat domain, whereas no significant phosphorylation outside this region was detected. Phosphorylation occurs mainly on Ser-262 located in the first repeat. This largely abolishes tau's binding to microtubules and makes them dynamically unstable, in contrast to other protein kinases that phosphorylate tau at or near the repeat domain. The data suggest a role for this novel kinase in cellular events involving rearrangement of the microtuble-associated proteins/microtubule arrays and their pathological degeneration in Alzheimer's disease.

    The Journal of biological chemistry 1995;270;13;7679-88

  • Identification of Ser38 as the site in cardiac sarcoplasmic reticulum Ca(2+)-ATPase that is phosphorylated by Ca2+/calmodulin-dependent protein kinase.

    Toyofuku T, Curotto Kurzydlowski K, Narayanan N and MacLennan DH

    Banting and Best Department of Medical Research, University of Toronto, C. H. Best Institute, Ontario, Canada.

    In previous studies (Xu, A., Hawkins, C., and Narayanan, N. (1993) J. Biol. Chem. 268, 8394-8397), the Ca(2+)-ATPase of cardiac muscle sarcoplasmic reticulum (SERCA2) was shown to be phosphorylated by Ca2+/calmodulin-dependent protein kinase II (CaM kinase) on a serine residue, likely to be either Ser38, Ser167, or Ser531. SERCA2 and SERCA2 mutants S38A, S167A, and S531A were expressed in HEK-293 cells and tested for phosphorylation with CaM kinase. Mutant S38A was not phosphorylated, while mutants S167A and S531A were phosphorylated, suggesting that Ser38 is the site of CaM kinase phosphorylation in SERCA2. This conclusion was supported by the observation that phosphorylation of SERCA2 and mutants S167A and S531A by CaM kinase increased the Vmax for Ca2+ transport, while the Vmax for Ca2+ transport by mutant S38A was unaffected by exposure to a phosphorylation reaction mix. SERCA1, containing a potential CaM kinase phosphorylation site at Ser167 and two SERCA1 mutants, K35R plus H38S and T532S, in which potential CaM kinase sites were created, were not phosphorylated by CaM kinase, and Vmax for Ca2+ transport was unaffected by exposure to a phosphorylation reaction mix. Thus phosphorylation of Ser38 in SERCA2 results in a unique activation of Vmax for Ca2+ transport, providing a potential regulatory mechanism for Ca2+ removal from cardiac and other tissues in which SERCA2 is expressed.

    The Journal of biological chemistry 1994;269;42;26492-6

  • Identification of the major physiologic phosphorylation site of human keratin 18: potential kinases and a role in filament reorganization.

    Ku NO and Omary MB

    Palo Alto Veterans Administration Medical Center, CA 94304.

    There is ample in vitro evidence that phosphorylation of intermediate filaments, including keratins, plays an important role in filament reorganization. In order to gain a better understanding of the function of intermediate filament phosphorylation, we sought to identify the major phosphorylation site of human keratin polypeptide 18 (K18) and study its role in filament assembly or reorganization. We generated a series of K18 ser-->ala mutations at potential phosphorylation sites, followed by expression in insect cells and comparison of the tryptic 32PO4-labeled patterns of the generated constructs. Using this approach, coupled with Edman degradation of the 32PO4-labeled tryptic peptides, and comparison with tryptic peptides analyzed after labeling normal human colonic tissues, we identified ser-52 as the major K18 physiologic phosphorylation site. Ser-52 in K18 is not glycosylated and matches consensus sequences for phosphorylation by CAM kinase, S6 kinase and protein kinase C, and all these kinases can phosphorylate K18 in vitro predominantly at that site. Expression of K18 ser-52-->ala mutant in mammalian cells showed minimal phosphorylation but no distinguishable difference in filament assembly when compared with wild-type K18. In contrast, the ser-52 mutation played a clear but nonexclusive role in filament reorganization, based on analysis of filament alterations in cells treated with okadaic acid or arrested at the G2/M stage of the cell cycle. Our results show that ser-52 is the major physiologic phosphorylation site of human K18 in interphase cells, and that its phosphorylation may play an in vivo role in filament reorganization.

    Funded by: NIAAA NIH HHS: AA0947A-01; NIDDK NIH HHS: DK38707

    The Journal of cell biology 1994;127;1;161-71

  • Identification of phosphorylation sites on glial fibrillary acidic protein for cdc2 kinase and Ca(2+)-calmodulin-dependent protein kinase II.

    Tsujimura K, Tanaka J, Ando S, Matsuoka Y, Kusubata M, Sugiura H, Yamauchi T and Inagaki M

    Department of Neurophysiology, Tokyo Metropolitan Institute of Gerontology.

    We identified the phosphorylation sites of glial fibrillary acidic protein (GFAP) for cdc2 kinase and Ca(2+)-calmodulin (CaM)-dependent protein kinase II. GFAP was phosphorylated to approximately 0.2 mol of phosphate/mol of GFAP by cdc2 kinase, and this phosphorylation did not induce disassembly of the filament structure. On the other hand, GFAP was phosphorylated to approximately 1.9 mol of phosphate/mol of GFAP by Ca(2+)-CaM-dependent protein kinase II, and this phosphorylation did induce disassembly of the filament. Sequential analysis of the purified phosphopeptides revealed that only Ser8 on GFAP was phosphorylated by cdc2 kinase, whereas Ser13, Ser17, Ser34, and Ser389 on GFAP were phosphorylated by Ca(2+)-CaM-dependent protein kinase II.

    Journal of biochemistry 1994;116;2;426-34

  • A growth factor-induced kinase phosphorylates the serum response factor at a site that regulates its DNA-binding activity.

    Rivera VM, Miranti CK, Misra RP, Ginty DD, Chen RH, Blenis J and Greenberg ME

    Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115.

    A signaling pathway by which growth factors may induce transcription of the c-fos proto-oncogene has been characterized. Growth factor stimulation of quiescent fibroblasts activates a protein kinase cascade that leads to the rapid and transient phosphorylation of the serum response factor (SRF), a regulator of c-fos transcription. The in vivo kinetics of SRF phosphorylation and dephosphorylation parallel the activation and subsequent repression of c-fos transcription, suggesting that this phosphorylation event plays a critical role in the control of c-fos expression. The ribosomal S6 kinase pp90rsk, a growth factor-inducible kinase, phosphorylates SRF in vitro at serine 103, the site that becomes newly phosphorylated upon growth factor stimulation in vivo. Phosphorylation of serine 103 significantly enhances the affinity and rate with which SRF associates with its binding site, the serum response element, within the c-fos promoter. These results suggest a model in which the growth factor-induced phosphorylation of SRF at serine 103 contributes to the activation of c-fos transcription by facilitating the formation of an active transcription complex at the serum response element.

    Funded by: NCI NIH HHS: CA6595, R01 CA43855

    Molecular and cellular biology 1993;13;10;6260-73

  • Nitric oxide synthase regulatory sites. Phosphorylation by cyclic AMP-dependent protein kinase, protein kinase C, and calcium/calmodulin protein kinase; identification of flavin and calmodulin binding sites.

    Bredt DS, Ferris CD and Snyder SH

    Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.

    Nitric oxide (NO) is an important molecular messenger accounting for endothelial-derived relaxing activity in blood vessels, mediating cytotoxic actions of macrophages, and functioning as a neurotransmitter in the brain and periphery. NO synthase (NOS) from brain has been purified to homogeneity and molecularly cloned. We now report that NOS is stoichiometrically phosphorylated by cAMP dependent protein kinase, protein kinase C, and calcium/calmodulin-dependent protein kinase, with each kinase phosphorylating a different serine site on NOS. Activation of PKC in transfected cells reduces NOS enzyme activity by approximately 77% in intact cells and by 50% in protein homogenates from these cells. Utilizing fluorescence spectroscopy we find that purified monomer NOS contains 1 molar equivalent of both FMN and FAD. This stoichiometry is supported by enzymatic digestion of the flavins with phosphodiesterase, and titration of the FMN with a specific FMN binding protein. We demonstrate that purified NOS is labeled by a photoaffinity derivative of calmodulin. These recognition sites on NOS provide multiple means for regulation of NO levels and "cross-talk" between second messenger systems.

    Funded by: NIDA NIH HHS: DA-00074; NIGMS NIH HHS: GM-07309; NIMH NIH HHS: MH-18501; ...

    The Journal of biological chemistry 1992;267;16;10976-81

  • PKC epsilon-related kinase associates with and phosphorylates cytokeratin 8 and 18.

    Omary MB, Baxter GT, Chou CF, Riopel CL, Lin WY and Strulovici B

    Stanford University School of Medicine, Gastroenterology Division, California 94305.

    A 40-kD protein kinase C (PKC)epsilon related activity was found to associate with human epithelial specific cytokeratin (CK) polypeptides 8 and 18. The kinase activity coimmunoprecipitated with CK8 and 18 and phosphorylated immunoprecipitates of the CK. Immunoblot analysis of CK8/18 immunoprecipitates using an anti-PKC epsilon specific antibody showed that the 40-kD species, and not native PKC epsilon (90 kD) associated with the cytokeratins. Reconstitution experiments demonstrated that purified CK8 or CK18 associated with a 40-kD tryptic fragment of purified PKC epsilon, or with a similar species obtained from cells that express the fragment constitutively but do not express CK8/18. A peptide pseudosubstrate specific for PKC epsilon inhibited phosphorylation of CK8/18 in intact cells or in a kinase assay with CK8/18 immunoprecipitates. Tryptic peptide map analysis of the cytokeratins that were phosphorylated by purified rat brain PKC epsilon or as immunoprecipitates by the associated kinase showed similar phosphopeptides. Furthermore, PKC epsilon immunoreactive species and CK8/18 colocalized using immunofluorescent double staining. We propose that a kinase related to the catalytic fragment of PKC epsilon physically associates with and phosphorylates cytokeratins 8 and 18.

    The Journal of cell biology 1992;117;3;583-93

  • Calcium-regulated phosphorylation within the leucine zipper of C/EBP beta.

    Wegner M, Cao Z and Rosenfeld MG

    Howard Hughes Medical Institute, University of California, San Diego, La Jolla 92093-0648.

    Alterations in intracellular calcium levels activate several signal transduction pathways resulting in distinct patterns of gene expression. Here, a pathway for calcium-mediated signals is demonstrated that involves C/EBP beta, a member of the bZip family of transcription factors. In pituitary cells C/EBP beta was phosphorylated in response to increased intracellular calcium concentrations as a consequence of the activation of a calcium-calmodulin-dependent protein kinase. Phosphorylation of serine at position 276 within the leucine zipper of C/EBP beta appeared to confer calcium-regulated transcriptional stimulation of a promoter that contained binding sites for C/EBP beta.

    Science (New York, N.Y.) 1992;256;5055;370-3

  • Mechanism of desensitization of the epidermal growth factor receptor protein-tyrosine kinase.

    Countaway JL, Nairn AC and Davis RJ

    Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester 01605.

    The intrinsic protein-tyrosine kinase activity of the epidermal growth factor (EGF) receptor is required for signal transduction. Increased protein-tyrosine kinase activity is observed following the binding of EGF to the receptor. However, signaling is rapidly desensitized during EGF treatment. We report that EGF receptors isolated from desensitized cells exhibit a lower protein-tyrosine kinase activity than EGF receptors isolated from control cells. The mechanism of desensitization of kinase activity can be accounted for, in part, by the EGF-stimulated phosphorylation of the receptor at Ser1046/7, a substrate for the multifunctional calmodulin-dependent protein kinase II in vitro. Mutation of Ser1046/7 by replacement with Ala residues blocks desensitization of the EGF receptor protein-tyrosine kinase activity. Furthermore, this mutation causes a marked inhibition of the EGF-stimulated endocytosis and down-regulation of cell surface receptors. Thus, the phosphorylation site Ser1046/7 is required for EGF receptor desensitization in EGF-treated cells. This regulatory phosphorylation site is located at the carboxyl terminus of the EGF receptor within the subdomain that binds src homology 2 regions of signaling molecules.

    Funded by: NCI NIH HHS: CA39240; NIGMS NIH HHS: GM37845

    The Journal of biological chemistry 1992;267;2;1129-40

  • Protein kinase A phosphorylates retinal phosducin on serine 73 in situ.

    Lee RH, Brown BM and Lolley RN

    Department of Anatomy and Cell Biology, University of California, Los Angeles 90024.

    Photoreceptors of vertebrate retinas contain a 33,000-dalton phosphoprotein, phosducin, which complexes with the beta, gamma subunits of the photoreceptor G-protein (guanine nucleotide-binding protein), transducin. In situ, the retinal content of phosphorylated phosducin is modulated by light in conjunction with light-triggered changes in intracellular cyclic nucleotide concentration. In vitro, phosducin is phosphorylated by either exogenous or endogenous protein kinase A. 32P-Labeled rat retina phosducin was isolated by immunoprecipitation either after phosphorylation by protein kinase A in the presence of [gamma-32P]ATP or after incubation of retinas in darkness with 32Pi. In either case, phosphoamino acid analysis showed that greater than 98% of 32P was linked to serine, with less than 2% to threonine. Two-dimensional peptide mapping showed that [32P]phosphoserine was associated with the same characteristic set of tryptic peptides. Furthermore, Cleveland peptide analysis using four different proteases showed that either sample exhibited identical patterns of phosphopeptides which were characteristic of the protease used. Identical phosphopeptide maps were also obtained from 32P-labeled bovine retina phosducin, indicating that the serine phosphorylation site for protein kinase A is conserved between rat and bovine. Edman degradation of phosphopeptides derived from 32P-labeled bovine phosducin showed that radioactive phosphate was incorporated into serine residue 73 which is located within a consensus phosphorylation sequence for protein kinase A (-R-K-M-S73(P)-). These observations are uniformly in agreement with protein kinase A being the endogenous kinase that phosphorylates phosducin in vivo.

    Funded by: NEI NIH HHS: EY-7860

    The Journal of biological chemistry 1990;265;26;15860-6

  • Ca2+/calmodulin-dependent protein kinase II: localization in the interphase nucleus and the mitotic apparatus of mammalian cells.

    Ohta Y, Ohba T and Miyamoto E

    Department of Pharmacology, Kumamoto University Medical School, Japan.

    Indirect immunofluorescence was used to determine the distribution of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) in rat embryo fibroblast 3Y1 cells, rat C6 glioma cells, and human epidermoid carcinoma KB cells. During interphase at growing phase, CaM kinase II was localized diffusely in the cytoplasm and in the nucleus. In the nucleus, the enzyme was localized within the whole nuclear matrix in which the enzyme was specially concentrated in nucleoli. During mitosis, CaM kinase II was found to be a dynamic component of the mitotic apparatus, particularly present at microtubule-organizing centers. In metaphase and anaphase, CaM kinase II was observed at centrosomes and between the spindle poles. During telophase, CaM kinase II was condensed as a bright fluorescent dot at the midzone of the intercellular bridge between two daughter cells, while tubulin was found at each side of the midbody. Colchicine, a microtubule inhibitor, disorganized the tubulin- and CaM kinase II specific fluorescent structure of mitotic 3Y1 cells. In cold-treated cells, CaM kinase II was localized predominantly at centrosomes. The localization of CaM kinase II in the cell nucleus and the mitotic apparatus suggests that the enzyme may play a role in the cell cycle progression of mammalian cells.

    Proceedings of the National Academy of Sciences of the United States of America 1990;87;14;5341-5

  • Ca2(+)-calmodulin-dependent protein kinase II phosphorylates various types of non-epithelial intermediate filament proteins.

    Tokui T, Yamauchi T, Yano T, Nishi Y, Kusagawa M, Yatani R and Inagaki M

    Laboratory of Experimental Radiology, Aichi Cancer Center Research Institute, Japan.

    We have investigated the actions of Ca2(+)-calmodulin (CaM)-dependent protein kinase II on various types of non-epithelial intermediate filament proteins, vimentin, desmin, glial fibrillary acidic protein (GFAP) and neurofilament triplet proteins. Most of these filament proteins could serve as substrates. The effects of phosphorylation on the filamentous structure of vimentin were investigated in sedimentation experiments and by using electron microscopy. The amount of unassembled vimentin increased linearly with increased phosphorylation. However, the extent of the effect of phosphorylation on the potential to polymerize was also affected by the MgCl2 concentration, under conditions for reassembly. The actions of Ca2(+)-CaM-dependent protein kinase II on non-epithelial intermediate filaments under physiological conditions are given attention.

    Biochemical and biophysical research communications 1990;169;3;896-904

  • Phosphorylation sites linked to glial filament disassembly in vitro locate in a non-alpha-helical head domain.

    Inagaki M, Gonda Y, Nishizawa K, Kitamura S, Sato C, Ando S, Tanabe K, Kikuchi K, Tsuiki S and Nishi Y

    Laboratory of Experimental Radiology, Aichi Cancer Center Research Institute, Japan.

    Glial fibrillary acidic protein (GFAP), the intermediate filament component of astroglial cells, can serve as an excellent substrate for both cAMP-dependent protein kinase and protein kinase C, in vitro. GFAP phosphorylated by each protein kinase does not polymerize, and the filaments that do polymerize tend to depolymerize after phosphorylation. Dephosphorylation of phospho-GFAP by phosphatase led to a recovery of the polymerization competence of GFAP. Most of the phosphorylation sites for cAMP-dependent protein kinase and protein kinase C on GFAP are the same, Ser-8, Ser-13, and Ser-34. cAMP-dependent protein kinase has one additional phosphorylation site, Thr-7. All the sites are located within the amino-terminal non-alpha-helical head domain of GFAP. These observations pave the way for in vivo studies on organization of glial filaments.

    The Journal of biological chemistry 1990;265;8;4722-9

  • Molecular cloning of a brain-specific calcium/calmodulin-dependent protein kinase.

    Lin CR, Kapiloff MS, Durgerian S, Tatemoto K, Russo AF, Hanson P, Schulman H and Rosenfeld MG

    A calcium/calmodulin-dependent protein kinase type II (CaM-K) alpha-subunit cDNA has been cloned from rat brain. This enzyme is encoded by a 5.1-kilobase mRNA expressed exclusively in the brain. Hybridization histochemistry reveals that the CaM-K mRNA expression corresponds to the distribution of the immunoreactive alpha-subunit protein, suggesting that the high enzyme levels in specific brain areas reflect regional differences in gene expression. The sequence of CaM-K alpha-subunit cDNA indicates a 478-amino acid (54-kDa) protein with three functional domains. The domain organization suggests a structural model for calcium/calmodulin-dependent and independent states that might subserve short- and long-term responses to transient stimuli.

    Proceedings of the National Academy of Sciences of the United States of America 1987;84;16;5962-6

Gene lists (11)

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
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
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
L00000032 G2C Homo sapiens Pocklington H1 Human orthologues of cluster 1 (mouse) from Pocklington et al (2006) 21
L00000049 G2C Homo sapiens TAP-PSD-95-CORE TAP-PSD-95 pull-down core list (ortho) 120
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
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EUROSPIN (FP7-HEALTH-241498), SynSys (FP7-HEALTH-242167) and GENCODYS (FP7-HEALTH-241995).

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