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nRap GEP: A novel neural GDP/GTP exchange protein for Rap1 small G protein that interacts with synaptic scaffolding molecule (S-SCAM)

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BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 1999年第1期265卷 38-44页

作者： Ohtsuka, T Hata, Y Ide, N Yasuda, T Inoue, E Inoue, T Mizoguchi, A Takai, Y Osaka Univ Fac Med Grad Sch Med Dept Mol Biol & Biochem Suita Osaka 5650871 Japan JCR Pharmaceut Co Ltd ERATO Takai Biotimer Project Japan Sci & Technol CorpNishi Ku Kobe Hyogo 6512241 Japan Tokyo Med & Dent Univ Dept Med Biochem Bunkyo Ku Tokyo 1138519 Japan Kyoto Univ Grad Sch Dept Anat & Neurobiol Kyoto 6068315 Japan

Synaptic scaffolding molecule (S-SCAM) has six PDZ domains through which it interacts with N-methyl-D-aspartate receptors and neuroligin at synaptic junctions. We isolated here a novel S-SCAM-binding protein. This protein has one PDZ, one Ras association, one Ras GDP/GTP exchange protein (Ras GEP) domain, and one C-terminal consensus motif for binding to PDZ domains. We named it nRap GEP (neural Rap GEP). nRap GEP moreover has an incomplete cyclic AMP (cAMP)-binding (CAB) domain. The domain organization of nRap GEP is similar to that of Epac/cAMP-guanine nucleotide exchange factor (GEF) I, except that Epac/cAMP-GEFI has complete CAB and Ras GEP domains but lacks the other two domains and the C-terminal motif. nRap GEP showed GEP activity for Rap1 but did not bind cAMP, nRap GEP was specifically expressed in rat brain. Immunohistochemical analysis revealed that nRap GEP and S-SCAM were localized at synaptic areas of the cerebellum. These results suggest that nRap GEP is a novel neural Rap1-specific GEP which is associated with S-SCAM. (C) 1999 Academic Press.

关键词：氨基酸序列结合部位脑/代谢载体蛋白质类/化学载体蛋白质类/代谢克隆分子 GTP结合蛋白质类/化学 GTP结合蛋白质类/遗传学 GTP结合蛋白质类/代谢鸟嘌呤核苷酸交换因子类动力学分子序列数据神经组织蛋白质类/化学神经组织蛋白质类/代谢重组蛋白质类/化学重组蛋白质类/代谢序列比对序列同源性氨基酸亚细胞部分/代谢突触/代谢动物人类大鼠

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FGF-2 potentiates Ca²⁺-dependent inactivation of NMDA receptor currents in hippocampal neurons

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JOURNAL OF NEUROPHYSIOLOGY 1999年第6期82卷 3367-3377页

作者： Boxer, AL Moreno, H Rudy, B Ziff, EB NYU Med Ctr Dept Biochem Howard Hughes Med Inst New York NY 10016 USA NYU Med Ctr Dept Physiol & Neurosci New York NY 10016 USA

Peptide growth factors such as the neurotrophins and fibroblast growth factors have potent effects on synaptic transmission, development, and cell survival. We report that chronic (hours) treatment with basic fibroblast growth factor (FGF-2) potentiates Ca2+-dependent N-methyl-D-aspartate (NMDA) receptor inactivation in cultured hippocampal neurons. This effect is specific for the NMDA-subtype of ionotropic glutamate receptor and FGF-2. The potentiated inactivation requires ongoing protein synthesis during growth factor treatment and the activity of protein phosphatase 2B (PP2B or calcineurin) during agonist application. These results suggest a mechanism by which FGF-2 receptor signaling may regulate neuronal survival and synaptic plasticity.

关键词：辅肌动蛋白/生理学钙神经素/代谢钙/生理学钙通道/生理学细胞培养的电刺激电生理学成纤维细胞生长因子2/药理学海马/细胞学海马/药物作用免疫组织化学离子通道闸门/药物作用膜电位/生理学神经组织蛋白质类/代谢神经元/药物作用膜片钳术 RNA 信使/生物合成大鼠 Sprague-Dawley 受体 N-甲基-D-天冬氨酸/拮抗剂和抑制剂逆转录聚合酶链反应动物大鼠

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Direct binding of Reelin to VLDL receptor and ApoE receptor 2 induces tyrosine phosphorylation of disabled-1 and modulates tau phosphorylation

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NEURON 1999年第2期24卷 481-489页

作者： Hiesberger, T Trommsdorff, M Howell, BW Goffinet, A Mumby, MC Cooper, JA Herz, J Univ Texas SW Med Ctr Dept Mol Genet Dallas TX 75235 USA Univ Texas SW Med Ctr Dept Pharmacol Dallas TX 75235 USA Fred Hutchinson Canc Res Ctr Seattle WA 98109 USA Univ Namur Sch Med Neurobiol Unit B-5000 Namur Belgium

The large extracellular matrix protein Reelin is produced by Cajal-Retzius neurons in specific regions of the developing brain, where it controls neuronal migration and positioning. Genetic evidence suggests that interpretation of the Reelin signal by migrating neurons involves two neuronal cell surface proteins, the very low density lipoprotein receptor (VLDLR) and the apoE receptor 2 (ApoER2) as well as a cytosolic adaptor protein, Disabled-1 (Dab1). We show that Reelin binds directly and specifically to the ectodomains of VLDLR and ApoER2 in vitro and that blockade of VLDLR and ApoER2 correlates with loss of Reelin-induced tyrosine phosphorylation of Disabled-1 in cultured primary embryonic neurons. Furthermore, mice that lack either Reelin or both VLDLR and ApoER2 exhibit hyperphosphorylation of the microtubule-stabilizing protein tau. Taken together, these findings suggest that Reelin acts via VLDLR and ApoER2 to regulate Disabled-1 tyrosine phosphorylation and microtubule function in neurons.

关键词：细胞黏附分子神经元/遗传学细胞黏附分子神经元/代谢细胞外基质蛋白质类/遗传学细胞外基质蛋白质类/代谢低密度脂蛋白受体相关蛋白-1 小鼠基因敲除/遗传学神经组织蛋白质类/代谢磷酰化蛋白质亚型/代谢受体 LDL/遗传学受体 LDL/代谢受体脂蛋白/遗传学受体脂蛋白/代谢丝氨酸内肽酶类酪氨酸/代谢 tau蛋白质类/代谢动物人类小鼠

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The semaphorin receptor plexin-B1 specifically interacts with active Rac in a ligand-dependent manner

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2000年第23期97卷 12457-12462页

作者： Vikis, HG Li, WQ He, ZG Guan, KL Univ Michigan Sch Med Dept Biol Chem Ann Arbor MI 48109 USA Univ Michigan Inst Gerontol Ann Arbor MI 48109 USA Childrens Hosp Div Neurosci Boston MA 02115 USA

Semaphorin molecules serve as axon guidance signals that regulate the navigation of neuronal growth cones. Semaphorins have also been implicated in other biological processes. including the immune response. Plexins, acting either alone or in complex with neuropilins. have recently been identified as functional semaphorin receptors. However, the mechanisms of signal transduction by plexins remain largely unknown. We have demonstrated a direct interaction between plexin-B1 and activated Rac. Rac specifically interacts with the cytosolic domain of plexin-B1, but not with that of plexin-A3 or -C1. Neither RhoA nor Cdc42 interacts with plexin-B1, indicating that the Rac/plexin-B1 interaction is highly specific. The binding of GTP and the integrity of the Rac effector domain are required for the interaction with plexin-B1. Furthermore, we have identified that a Cdc42/Rac interactive binding (CRIB) motif in the cytosolic domain of plexin-B1 is essential for its interaction with active pac. We have also observed that the semaphorin CD100, a ligand for plexin-B1, stimulates the interaction between plexin-B1 and active Rac. Our results support a model by which activated Rac plays a role in mediating semaphorin signals, resulting in reorganization of actin cytoskeletal structure.

关键词：氨基酸特征结构抗原 CD 结合部位细胞系配体膜糖蛋白类/代谢神经组织蛋白质类/化学神经组织蛋白质类/代谢受体细胞表面/化学受体细胞表面/代谢信号素类构效关系 rac1GTP结合蛋白质/代谢人类

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Enhanced association of mutant triosephosphate isomerase to red cell membranes and to brain microtubules

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2000年第3期97卷 1026-1031页

作者： Orosz, F Wágner, G Liliom, K Kovács, J Baróti, K Horány, M Farkas, T Hollán, S Ovádi, J Hungarian Acad Sci Biol Res Ctr Inst Enzymol H-1518 Budapest Hungary Eotvos Lorand Univ Fac Sci Dept Gen Zool H-1445 Budapest Hungary Natl Inst Haematol & Immunol H-1113 Budapest Hungary Hungarian Acad Sci Inst Biochem Biol Res Ctr H-6701 Szeged Hungary

In a Hungarian family with triosephosphate isomerase (TPI;D-glyceraldehyde-3-phosphate keto-isomerase, EC 5.3.1.1) deficiency, two germ-line identical, but phenotypically differing compound heterozygote brothers tone of them with neurological disorder) have been identified with the same very low (< 5%) TPI activity and 20- or 40-fold higher erythrocyte dihydroxyacetone phosphate levels as compared with normal controls. Our present studies with purified TPI and hemolysates revealed the binding of TPI, and the binding of human wild-type and mutant TPIs in hemolysate, to the red cell membrane, and the interference of binding with other hemolysate proteins. The binding of the mutant TPI is enhanced as compared with the wild-type enzyme. The increased binding is influenced by both the altered structure of the mutant and the changes in the red cell membrane. Compared with binding of glyceraldehyde-3-phosphate dehydrogenase, the isomerase binding is much less sensitive to ionic strength or blocking of the N-terminal tail of the band-3 transmembrane protein. The binding of TPIs to the membrane decreases the isomerase activity, resulting in extremely high dihydroxyacetone phosphate levels in deficient cells. In cell-free brain extract, tubulin copolymerizes with TPI and with other cytosolic proteins forming highly decorated microtubules as shown by immunoblot analysis with anti-TPI antibody and by electron microscopic images. The efficacy order of TPI binding to microtubules is propositus > brother without neurological disorder > normal control. This distinct microcompartmentation of mutant proteins may be relevant in the development of the neurodegenerative process in TPI deficiency and in other, more common neurological diseases.

关键词：贫血溶血性先天性/酶学贫血溶血性先天性/遗传学基底神经节疾病/酶学基底神经节疾病/遗传学结合竞争性生物转运脑/酶学细胞膜/代谢密码子/遗传学二羟丙酮磷酸/代谢红细胞/酶学杂合子大分子物质微管/酶学神经组织蛋白质类/缺乏神经组织蛋白质类/遗传学神经组织蛋白质类/代谢点突变蛋白质结合终止区遗传丙糖磷酸异构酶/缺乏丙糖磷酸异构酶/遗传学丙糖磷酸异构酶/代谢微管蛋白/代谢动物牛人类男(雄)性大鼠

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Two cis-acting elements in the 3′ untranslated region of α-CaMKII regulate its dendritic targeting

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NATURE NEUROSCIENCE 2000年第11期3卷 1079-1084页

作者： Mori, Y Imaizumi, K Katayama, T Yoneda, T Tohyama, M Osaka Univ Grad Sch Med Dept Anat & Neurosci Suita Osaka 5650871 Japan Tanabe Seiyaku Corp Discovery Res Lab Yodogawa Ku Osaka 5320031 Japan Japan Sci & Technol Corp CREST Kawaguchi Saitama 3320012 Japan

Dendritic localization of the or subunit of Ca2+/calmodulin-dependent protein kinase II (alpha CaMKII) mRNA in CNS neurons requires its 3' untranslated region (3'UTR). We investigated this targeting mechanism by identifying two cis-acting elements in the 3'UTR. One is a 30-nucleotide element that mediated dendritic translocation. A homologous sequence in the 3'UTR of neurogranin, transcripts of which also reside in dendrites, also funtioned in cis to promote its dendritic transport. Other putative elements in the alpha CaMKII mRNA inhibit its transport in a resting state. This inhibition was removed in depolarized neurons, and such activity-dependent derepression was a primary requirement for their dendritic targeting.

关键词：碱基序列/遗传学钙调蛋白结合蛋白质类/遗传学钙调蛋白结合蛋白质类/代谢细胞培养的克隆分子/方法树突/遗传学树突/代谢基因表达谱/方法海马记忆/生理学分子序列数据神经组织蛋白质类/遗传学神经组织蛋白质类/代谢神经颗粒素 RNA 信使/遗传学大鼠 Wistar 动物大鼠

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G protein modulation of recombinant P/Q-type calcium channels by regulators of G protein signalling proteins

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JOURNAL OF PHYSIOLOGY-LONDON 2000年第1期528卷 65-77页

作者： Mark, MD Wittemann, S Herlitze, S Univ Tubingen Dept Physiol 2 D-72074 Tubingen Germany

1. Fast synaptic transmission is triggered by the activation of presynaptic Ca2+ channels which can be inhibited by G beta gamma subunits via G protein-coupled receptors (GPCR). Regulators of G protein signalling (RGS) proteins are GTPase-accelerating proteins (GAPs), which are responsible fur >100-fold increases in the GTPase activity of G proteins and might be involved in the regulation of presynaptic Ca2+ channels. In this study we investigated the effects of RGS2 on G protein modulation of recombinant P/Q-type channels expressed in a human embryonic kidney (HEK293) cell line using whole-cell recordings. 2. RGS2 markedly accelerates transmitter-mediated inhibition and recovery from inhibition of Ba2+ currents (I-Ba) through P/Q-type channels heterologously expressed with the muscarinic acetylcholine receptor M2 (mAChR M2). 3. Both RGS2 and RGS4 modulate the prepulse facilitation properties of P/Q-type Ca2+ channels. G protein reinhibition is accelerated, while release from inhibition is slowed. Those kinetics depend on the availability of G protein alpha and beta gamma subunits which is altered by RGS proteins. 4. RGS proteins unmask the Ca2+ channel beta subunit modulation of Ca2+ channel G protein inhibition. In the presence of RGS2, P/Q-type channels containing the beta (2a) and beta (3) subunit;reveal significantly altered kinetics of G protein modulation and increased facilitation compared to Ca2+ channels coexpressed with the beta (1b) or beta (4) subunit.

关键词：钡/药理学钙通道/遗传学钙通道/代谢钙通道 N型钙通道 P型/药物作用钙通道 P型/遗传学钙通道 P型/代谢钙通道 Q型/药物作用钙通道 Q型/遗传学钙通道 Q型/代谢细胞系 GTP结合蛋白质类/代谢 GTP结合蛋白质类/药理学鸟苷5'-O-(3-硫代三磷酸)/药理学离子通道闸门/药物作用肾/细胞学肾/代谢神经组织蛋白质类/遗传学神经组织蛋白质类/代谢膜片钳术磷蛋白类/生物合成蛋白质亚单位 RGS蛋白质类/代谢 RGS蛋白质类/药理学反应时间/药物作用受体毒蕈碱M2 受体毒蕈碱/代谢重组蛋白质类/药物作用重组蛋白质类/遗传学重组蛋白质类/代谢信号传导/药物作用人类

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Kinetics of synaptotagmin responses to Ca²⁺ and assembly with the core SNARE complex onto membranes

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NEURON 1999年第2期24卷 363-376页

作者： Davis, AF Bai, JH Fasshauer, D Wolowick, MJ Lewis, JL Chapman, ER Univ Wisconsin Sch Med Dept Physiol Madison WI 53706 USA Max Planck Inst Biophys Chem Dept Neurobiol D-37077 Gottingen Germany

The synaptic vesicle protein synaptotagmin I binds Ca2+ and is required for efficient neurotransmitter release. Here, we measure the response time of the C2 domains of synaptotagmin to determine whether synaptotagmin is fast enough to function as a Ca2+ sensor for rapid exocytosis. We report that synaptotagmin is "tuned" to sense Ca2+ concentrations that trigger neuronal exocytosis. The speed of response is unique to synaptotagmin I and readily satisfies the kinetic constraints of synaptic vesicle membrane fusion. We further demonstrate that Ca2+ triggers penetration of synaptotagmin into membranes and simultaneously drives assembly of synaptotagmin onto the base of the ternary SNARE (soluble N-ethylmaleimide-sensitive fusion protein [NSF] attachment receptor) complex, near the transmembrane anchor of syntaxin. These data support a molecular model in which synaptotagmin triggers exocytosis through its interactions with membranes and the SNARE complex.

关键词：钙/生理学钙结合蛋白质类动力学膜融合/生理学膜糖蛋白类/化学膜糖蛋白类/遗传学膜糖蛋白类/代谢膜蛋白质类/代谢膜/代谢神经组织蛋白质类/化学神经组织蛋白质类/遗传学神经组织蛋白质类/代谢重复序列核酸 SNARE蛋白质类序列同源性突触小泡/代谢突触结合蛋白质Ⅰ 突触结合蛋白质类膜泡运输蛋白质类动物大鼠

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Nuclear localization of the spinocerebellar ataxia type 7 protein, ataxin-7

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HUMAN MOLECULAR GENETICS 1999年第9期8卷 1657-1664页

作者： Kaytor, MD Duvick, LA Skinner, PJ Koob, MD Ranum, LPW Orr, HT Univ Minnesota Inst Human Genet Minneapolis MN 55455 USA Univ Minnesota Dept Lab Med & Pathol Minneapolis MN 55455 USA Univ Minnesota Dept Neurol Minneapolis MN 55455 USA Univ Minnesota Dept Biochem Minneapolis MN 55455 USA

Spinocerebellar ataxia type 7 (SCA7) belongs to a group of neurological disorders caused by a CAG repeat expansion in the coding region of the. associated gene. To gain insight into the pathogenesis of SCA7 and possible functions of ataxin-7, we examined the subcellular localization of ataxin-7 in transfected COS-1 cells using SCA7 cDNA clones with different CAG repeat tract lengths, In addition to a diffuse distribution throughout the nucleus, ataxin-7 associated with the nuclear matrix and the nucleolus. The location of the putative SCA7 nuclear localization sequence (NLS) was confirmed by fusing an ataxin-7 fragment with the normally cytoplasmic protein chicken muscle pyruvate kinase, Mutation of this NLS prevented protein from entering the nucleus. Thus, expanded ataxin-7 may carry out its pathogenic effects in the nucleus by altering a matrix-associated nuclear structure and/or by disrupting nucleolar function.

关键词： COS细胞荧光抗体技术肿瘤蛋白质类/代谢神经组织蛋白质类/遗传学神经组织蛋白质类/代谢核定位信号/遗传学核基质/代谢核蛋白质类/代谢丙酮酸激酶/代谢重组融合蛋白质类/代谢脊髓小脑共济失调/遗传学转录因子/代谢转染肿瘤抑制蛋白质类动物人类

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A close association of torsinA and α-synuclein in Lewy bodies -: A fluorescence resonance energy transfer study

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AMERICAN JOURNAL OF PATHOLOGY 2001年第1期159卷 339-344页

作者： Sharma, N Hewett, J Ozelius, LJ Ramesh, V McLean, PJ Breakefield, XO Hyman, BT Massachusetts Gen Hosp E Alzheimers Dis Res Unit Dept Neurol Charlestown MA 02129 USA Massachusetts Gen Hosp E Mol Neurogenet Unit Dept Neurol Charlestown MA 02129 USA Albert Einstein Coll Med Dept Mol Genet Bronx NY 10467 USA

TorsinA, a novel protein In which a mutation causes dominant, early onset torsion dystonia, may serve as a chaperone for misfolded proteins that require refolding or degradation. It has been hypothesized that misfolded alpha -synuclein, a protein in which two mutations cause autosomal dominantly inherited Parkinson's disease, serves as a nidus for the development of a Lewy body. We hypothesized that torsinA plays a role in the cellular processing of alpha -synuclein. We demonstrate that anti-torsin antibodies stain Lewy bodies and Lewy neurites in the substantia nigra and cortex. Using sensitive fluorescent resonance energy transfer (FRET) techniques, we find evidence of a close association between torsinA and alpha -synuclein in Lewy bodies.

关键词：载体蛋白质类能量传递海马/代谢免疫组织化学 Lewy体/代谢 Lewy体病/代谢显微镜检查共焦分子伴侣神经组织蛋白质类/代谢参考值光谱法荧光黑质/代谢突触核蛋白类 α突触核蛋白人类

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