| Project/Area Number |
11680789
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Neuroscience in general
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| Research Institution | NARA INSTITUTE OF SCIENCE AND TECHNOLOGY |
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Principal Investigator |
NAOYUKI Inagaki Nara Institute of Science and Technology, Division of Signal Transduction, Associate Professor, バイオサイエンス研究科, 助教授 (20223216)
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| Co-Investigator(Kenkyū-buntansha) |
KAIBUCHI Kozo Nagoya University, Medical School, Professor, 大学院・医学研究科, 教授 (00169377)
QUADOTA Hiroshi Nara Institute of Science and Technology, Division of Signal Transduction, Assistant Professor, バイオサイエンス研究科, 助手 (10294282)
AMANO Mutsuki Nara Institute of Science and Technology, Division of Signal Transduction, Assistant Professor, バイオサイエンス研究科, 助手 (90304170)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1999: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | Rho-kinase / CRMP-2 / Phosphorylation / Growth Cone / Axon / Dendrite / Cell Polarity / Rho-GEF |
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| Research Abstract |
We previously identified Rho-associated protein kinase (Rho-kinase) as a specific effector of Rho. In this research, we identified collapsin response medator protein-2 (CRMP-2), as a novel Rho-kinase substrate in brain. CRMP-2 is a neuronal protein whose expression is upregulated during development. Rho-kinase phosphorylated CRMP-2 at Thr-555 in vitro. We produced an antibody that specifically recognizes CRMP-2 phosphorylated at Thr-555. Using this antibody, we found that Rho-kinase phosphorylated CRMP-2 downstream of Rho in COS7 cells. Phosphorylation of CRMP-2 was observed in chick dorsal root ganglion (DRG) neurons during lysophosphatidic acid (LPA)-induced growth cone collapse, whereas the phosphorylation was not detected during Semaphorin-3A (Sema3A)-induced growth cone collapse. Both LPA-induced CRMP-2 phosphorylation and LPA-induced growth cone collapse were inhibitd by Rho-kinase inhibitor, HA1077 or Y-32885. LPA-induced growth cone collapse was also blocked by a dominant negat
… More
ive form of Rho-kinase. On the other hand, Sema3A-induced growth cone collapse was not significantly inhibited by Rho-kinase inhibitors. Furthermore, overexpression of a mutant CRMP-2 in which Thr-555 was replaced by Ala significantly inhibited LPA-induced growth cone collapse. These results demonstrate the existence of Rho-kinase-dependent and-independent pathways for growth cone collapse and suggest that CRMP-2 phosphorylation by Rho-kinase is involved in the former pathway.
Formation of an axon and dendrites is a fundamental step in neuronal development. In this research, we found that CRMP-2 was enriched in growing axons of cultured hippocampal neurons. Overexpression of CRMP-2 in the cells led to the formation of supemumerary axons without remarkable increase in the total number of neurites. CRMP-2 not only enhanced the formation of multiple axons during the initial stages of axon specification but also induced axon sprouting from already formed dendrites. Furthermore, expression of truncated CRMP-2 mutants suppressed the formation of primary axon in a dominant negative manner. Thus, local concentrations of CRMP-2 in neurites appear to play a critical role in axon induction of hippocampal neurons, thereby establishing and maintaining neuronal polarity. Win this research, we also cloned a novel Rho-GEF that is activated by IGF-1 receptors Less
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