2005 Fiscal Year Final Research Report Summary
Mechanism of expression of voltage-gated sodium and calcium channels
| Project/Area Number |
16390056
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General physiology
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| Research Institution | National Institute of Natural Sciences Okazaki Research Facilities |
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Principal Investigator |
OKAMURA Yasushi National Institute of Natural Sciences, Okazaki Research Facilities, Okazaki Institute for Integrative Bioscience, Professor, 岡崎総合バイオサイエンスセンター, 教授 (80201987)
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| Co-Investigator(Kenkyū-buntansha) |
KUKITA Fumio National Institute for Physiological Sciences, Assistant Professor, 生理学研究所, 助手 (40113427)
IWASAKI Hirohide National Institute for Physiological Sciences, Center for Brain Experiment, Assistant Professor, 生理学研究所・脳機能計測センター, 助手 (30342752)
EBIHARA Tatsuhiko AIST, Researcjer, 産業技術総合研究所・脳神経情報研究部門, 研究員 (00344119)
HAYASAKA Kiyoshi Yamagata Univertisy, Pediatrics, Professor, 医学部発達生体崩御学講座小児医学化学分野, 教授 (20142961)
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| Project Period (FY) |
2004 – 2005
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| Keywords | ion channel / voltage sensor / inactivation / persistent sodium current / sodium channel / ankyrin / PTEN / phosphatase |
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| Research Abstract |
Ankyrin-G, a modular protein, plays a critical role in clustering voltage-gated sodium channels (Nav channels) in nodes of Ranvier and initial segments of mammalian neurons. However, direct effects of ankyrin-G on electrophysiological properties of Nav channels remai elusive. In this study, we explored whether ankyrin-G has a role in modifying gating properties of the neuronal Nav1.6 channel that is predominantly localized at nodes of Ranvier and initial segments. TsA201 cells transfected with the human Nav1.6 cDNA alone exhibited significant persistent sodium current (Ina-p). On the other hand, Ina-p was barely detected upon co-expression with ankyrin-G. Ankyrin-B, another ankyrin, did not show such an effect. Expression of chimeras between the two isofrms of ankyrin suggests that the membrane-binding domain of ankyurin-G is critical for reducing the Ina-p of Nav1.6. These results suggest that ankyrin-G regulates neuronal excitability not only through clustering Nav channels but also
… More
by directly modifying their channel gating. Changes is membraine potential affect ion channels, and transporters, which then alter intracellular chemical conditions. Ohter signaling pathways coupled to membrane potential have been suggested but their underlying mechanism are unknown. We have identified a novel protein from the ascidian Ciona intestinalis which has a transmembrane voltage sensing domain homologous to the S1-S4 segments of voltage-gated channels and a cytoplasmic domain similar to phosphatase and tension homologue (PTEN). This protein, named Ci-VSP (voltage-sensor containing phosphatase), displays channel-like "gating" currents and directly translates changes in membrane potential into the turnover of phosphoinositides. The activity of the phosphoinositide phosphatase in Ci-VSP is tuned within a physiological range of membrane potential. Immunocytochemical studies show that Ci-VSP is expressed in Ciona sperm tail membranes, suggesting a role in sperm function or morphology. Our data demonstrate that voltage sensing can function beyond channel proteins and thus more ubiquitously than previously appreciated. Less
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Research Products
(33 results)
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[Journal Article] Comprehensive analysis of the ascidian genome reveals novel insights into the molecular evolution of ion channel genes2005
Author(s)
Y.Okamura^*, A.Nishino, Y.Murata, K.Nakajo, H.Iwasaki, Y.Ohtsuka, M.Tanaka-Kunishima, N.Takahashi, Y.Hara, T.Yoshida, M.Nishida, H.Okado, H.Watari, l.A.Meinertzhagen, N.Satoh, K.Takahashi, Y.Satou, Y.Okada, Y.Mori
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Journal Title
Physiol.Genomics 22
Pages: 269-682
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Tight junctions in Schwann cells of peripheral myelinated axons : a lesson from claudin-19-deficient mice2005
Author(s)
T.Miyamoto, K.Morita, D.Takemoto, K.Takeuchi, Y.Kitano, T.Miyakawa, K.Nakayama, Y.Okamura, H.Sasaki, Y.Miyachi, M.Furuse, S.Tsukita^*
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Journal Title
J.Cell Biol. 169
Pages: 527-538
Description
「研究成果報告書概要(欧文)」より
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