Molecular Mechanisms of Synaptic Vesicle Fusion

突触小泡融合的分子机制

• 批准号: 13480274
• 负责人: KIDOKORO Yoshiaki
• 金额: $ 8.77万
• 依托单位: Gunma University Graduate School of Medicine
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13480274/
• 关键词: Synaptotagmin I; Drosophila; synaptic currents; Ca-sensor; SNARE; spontaneous release; negative regulator; vesicle fusion

Synaptotagmin I (Syt I) project ; Syt I is widely considered to be a major Ca^<2+> sensor for fast transmitter release and has two putative Ca^<2+> binding domains, C2A and C2B. To elucidate its roles in synaptic transmission in situ, we studied synaptic currents at the neuromuscular junction (NMJ) of Drosophila embryos that have mutations in syt I. Synaptic currents were induced by nerve-stimulation in external solutions containing various concentrations of Ca^<2+> or by high K^+ solutions. In a null allele, syt I^<AD4>, synchronized synaptic currents were rarely evoked but not abolished. Its quantal content increased with [Ca^<2+>] with a slope of 0.7 in double logarithmic plot, in contrast to 2.7 in control. The slope of 0.9 in an allele that lacks entire C2B, syt I^<AD1>, was not different than in syt I^<AD4>, whereas in another allele, syt I^<AD3>, with one amino-acid substitution in C2B, it was 1.6. In normal saline, the miniature synaptic current (mini) frequency in syt I^<AD4> was not different than in other syt I alleles or in controls. Considering much smaller hypertonicity and Ca^<2+>-ionophore responses in syt I^<AD4>, this finding suggests that the release probability of docked/primed vesicles for spontaneous release is higher in the absence of Syt I. In high K^+ saline, the dependency of mini frequency on [Ca^<2+>] in syt I^<AD4> was less than that in controls, while that in syt I^<AD3> was even lower than in syt I^<AD4>. We conclude that Drosophila Syt I is a Ca^<2+> sensor for synchronized release but inhibits spontaneous quantal release.

突触结合蛋白I（Syt I）项目; Syt I被广泛认为是快速释放递质的主要Ca^<2+>感受器，并且具有两个推定的Ca^<2+>结合结构域，C2 A和C2B。为了阐明其在突触传递中的作用，我们研究了syt I突变的果蝇胚胎神经肌肉接头（NMJ）的突触电流。在含有不同浓度Ca^<2+>的外部溶液或高K^+溶液中刺激神经可诱导突触电流。在无效等位基因syt I^中<AD4>，同步突触电流很少被诱发，但没有被消除。其量子含量随[Ca^&lt;2+&gt;]的增加而增加，双对数图的斜率为0.7，而对照为2.7。缺失完整C2B的等位基因（syt I^）的斜率为0.9<AD1>，与syt I^没有差异<AD4>，而在另一个<AD3>C2B中有一个氨基酸取代的等位基因（syt I^）中，斜率为1.6。在生理盐水中，syt I的微型突触电流（mini）频率<AD4>与其他syt I等位基因或对照组没有差异。考虑到Syt I^中的高渗性和Ca^2+-离子载体响应小得多<AD4>，这一发现表明，在不存在Syt I的情况下，对接/引发的囊泡自发释放的释放概率更高。在高K^+盐水中，syt I^的最小频率对[Ca^2+]的依赖性<AD4>低于对照组，甚至低于syt <AD3>I^<AD4>。我们的结论是，果蝇Syt I是一个Ca^2+同步释放的传感器，但抑制自发的量子释放。

项目成果

Saitoe, M., Schwarz, T.L., Umbach, J.A., Gundersen, C.B., Kidokoro, Y.: "Response : Meaningless minis?"TRENDS in Neurosciences. 25. 385-386 (2002)

Saitoe, M.、Schwarz, T.L.、Umbach, J.A.、Gundersen, C.B.、Kidokoro, Y.：“反应：无意义的迷你？”神经科学趋势。

Saitoe, M., Schwaiz, T.L., Gundersen, C.B., Kidokoro, Y.: "Absence of junctional glutamate receptor clusters in Drosophila mutants lacking spontaneous transmitter release"Science. 293. 514-517 (2001)

Saitoe, M.、Schwaiz, T.L.、Gundersen, C.B.、Kidokoro, Y.：“缺乏自发递质释放的果蝇突变体中缺乏连接谷氨酸受体簇”《科学》。

Kidokoro, Y. and Suzuki, K.: "Multiple defects in synaptic transmission in Drosophila synaptotagmin-nul1 mutant embryos"Abst "Neurobiology of Drosophila" Cold Spring Harbor Lab Meeting. 32. (2001)

Kidokoro, Y. 和 Suzuki, K.：“果蝇突触结合蛋白-nul1 突变体胚胎中突触传递的多重缺陷”Abst“​​果蝇神经生物学”冷泉港实验室会议。

Suzuki, K., Grinnell, A.D., Kidokoro, Y.: "Hypertonicity-induced transmitter release at Drosophila neuromuscular junctions is partly mediated by integrins and cAMP/protein kinase A"Journal of Physiology(London). 538. 103-119 (2002)

Suzuki, K.、Grinnell, A.D.、Kidokoro, Y.：“果蝇神经肌肉接头处高渗性诱导的递质释放部分是由整联蛋白和 cAMP/蛋白激酶 A 介导的”生理学杂志（伦敦）。

Kidokoro, Y., Kuromi, H., Delgado, R., Maureira, C., Oliva, C., Labarca, P.: "Synaptic vesicle pools and plasticity of synaptic transmission at the Drosophila synapse"Brain Research Reviews. (in press).

Kidokoro, Y.、Kuromi, H.、Delgado, R.、Maureira, C.、Oliva, C.、Labarca, P.：“果蝇突触的突触囊泡池和突触传递的可塑性”大脑研究评论。