| Project/Area Number |
13470025
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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 medical chemistry
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| Research Institution | The University of Tokushima |
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Principal Investigator |
SASAKI Takuya The University of Tokushima, Graduate School of Medicine, Professor, 医学研究科, 教授 (40241278)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥14,500,000 (Direct Cost: ¥14,500,000)
Fiscal Year 2002: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2001: ¥10,500,000 (Direct Cost: ¥10,500,000)
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| Keywords | synaptic plasticity / vesicle transport / Rab3A / regulators / Rab3 GEP / Rab3 GAP / Rab GDI / Rabconnectin-3 / 神経伝達物質 / グルタミン酸受容体 / 神経伝達物質放出 / Rab3 GEP |
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| Research Abstract |
Long-term potentiation (LTP) is believed to provide an important key to understanding the cellular and molecular mechanisms by winch memories are formed and stored. Numerous studies strongly suggest that important mechanisms underlying LTP involves alternations in the release of glutamate from the presynaptic cells and the responsiveness of the postsynaptic glutamate receptors. Neurotransmitters including glutamate are released by synaptic vesicle exocytosis which is regulated by many components. They are classified into essential and modulatory ones for neurotransmitter release. Rab3A small G protein has been shown to be a modulatory component which regulates Ca^<2+>-dependent synaptic vesicle exocytosis. Rab3A cycles between the GDP-bound inactive form (GDP-Rab3A) and the GTP-bound active form (GTP-Rab3A) and translocates between the cytosol of the presynaptic nerve terminal and the membranes of synaptic vesicles and the presynaptic plasma membrane. The activation and the translocati
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on are regulated by three regulators (Rab GDI, Rab3 GAP, Rab3 GEP). Our previous studies on Rab GDIα-deficient mice had revealed that Rab GDIα is not essential for basal neurotransmitter release but suppress hyperexcitability via modulation of synaptic plasticity. In tins study, we found that Rab3 GEP-deficient mice show much more severe phenotypes and die immediately after birth due to respiratory insufficiency. Electron microscopic analysis of the neuromuscular junction revealed that total numbers of synaptic vesicles and active zones are markedly reduced. We isolated a novel protein that was co-immunoprecipitated with Rab3 GEP and GAP by their respective antibodies from the crude synaptic vesicle fraction of rat brain. This protein, named rabconnectin-3, bound at least both Rab3 GEP and GAP. Tissue and subcellular distribution analyses in rat indicated that rabcoithectin-3 was abundantly expressed in the brain where it was enriched in the synaptic vesicle fraction. Immunofluorescence and immunoelectron microscopy revealed that rabconnectin-3 was concentrated on synaptic vesicles at synapses. Less
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