The voltage-gated Ca2+ channel is the Ca2+ sensor of fast neurotransmitter release
The voltage-gated Ca2+ channel is the Ca2+ sensor of fast neurotransmitter release
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DOI：
10.1023/a:1015104105262
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发表时间：
2001-12-01
影响因子：
4
通讯作者：
Trus, M
中科院分区：
文献类型：
--
作者：
Atlas, D;Wiser, O;Trus, M
先前证明，在不存在Ca 2+进入的情况下，诱发分泌既不是通过膜去极化、诱导[Ca 2 +]（i）升高发生，也不是通过两者的组合发生（Ashery，U.，韦斯，C.，Sela，D.，斯皮拉湾E、和Atlas，D.（1993年）。受体通道1：217-220）。这些研究将胞吐作用所必需的[Ca 2 +]（i）升高与Ca 2+内流相对应。这使我们提出，该通道作为Ca 2+传感器，并通过与突触蛋白的物理和功能接触来调节分泌。这一观点得到了非洲爪蟾卵母细胞表达系统中重构的蛋白质-蛋白质相互作用和胰腺细胞中的释放实验的支持（Barg，S.，妈，X.，埃利亚松湖Galvanovskis，J.，Gopel，S. O.，Obermuller，S.，Platzer，J.，Renstrom，E.，Trus，M.，阿特拉斯，D.，Streissnig，G.，Rorsman，R.（2001）. Biophys. J.道：Wiser，O.，班尼特，M. K.，和Atlas，D.（1996年）。EMBO J. 15：4100-4110; Wiser，O.，Trus，M.，埃尔南德斯，A.，Renstrom，E.，Barg，S.，Rorsman，P和Atlas，D.（1999年）。Proc. Natl. Acad. Sci. U.S.A. 96：248-253）。在注射编码突触融合蛋白1A和SNAP-25的cRNA的卵母细胞中，Ca（v）1.2（LC型）和Ca（v）2.2（N型）Ca 2+通道的动力学被改变。突触融合蛋白1A跨膜结构域中的保守半胱氨酸（Cys 271、Cys 272）是必需的。突触结合蛋白I，囊泡相关蛋白，加速激活动力学表明Ca（v）2.2耦合到囊泡。突触融合蛋白1A、SNAP-25和突触结合蛋白对Ca（v）1.2和Ca（v）2.2动力学的独特修饰暗示了兴奋体的形成，这是通道与突触蛋白的引发融合复合物。Ca（v）1.2胞质结构域LC 753 -893作为显性负性调节剂，竞争性抑制胰岛细胞中通道相关囊泡（CAV）（易释放囊泡池（RRP））的胰岛素释放。提供了一种分子机制来解释拴系到SNARE相关的Ca 2+通道的囊泡的快速分泌。这种紧密排列有利于在通道去极化和Ca 2+结合期间诱导的构象变化传播到SNARE以触发分泌。结果表明，Ca 2+依赖性CAV（RRP）的快速释放，由Ca 2+与通道结合启动，在细胞内Ca 2+传感器的上游，从而建立了Ca 2+通道作为神经递质释放的Ca 2+传感器。
Previously it demonstrated that in the absence of Ca2+ entry, evoked secretion occurs neither by membrane depolarization, induction of [Ca2+](i) rise, nor by both combined (Ashery, U., Weiss, C., Sela, D., Spira, M. E., and Atlas, D. (1993). Receptors Channels 1:217-220.). These studies designate Ca2+ entry as opposed to [Ca2+](i) rise, essential for exocytosis. It led us to propose that the channel acts as the Ca2+ sensor and modulates secretion through a physical and functional contact with the synaptic proteins. This view was supported by protein-protein interactions reconstituted in the Xenopus oocytes expression system and release experiments in pancreatic cells (Barg, S., Ma, X., Elliasson, L., Galvanovskis, J., Gopel, S. O., Obermuller, S., Platzer, J., Renstrom, E., Trus, M., Atlas, D., Streissnig, G., and Rorsman, R (2001). Biophys. J.; Wiser, O., Bennett, M. K., and Atlas, D. (1996). EMBO J. 15:4100-4110; Wiser, O., Trus, M., Hernandez, A., Renstrom, E., Barg, S., Rorsman, P, and Atlas, D. (1999). Proc. Natl. Acad. Sci. U.S.A. 96:248-253). The kinetics of Ca(v)1.2 (Lc-type) and Ca(v)2.2 (N-type) Ca2+ channels were modified in oocytes injected with cRNA encoding syntaxin 1A and SNAP-25. Conserved cysteines (Cys271, Cys272) within the syntaxin 1A transmembrane domain are essential. Synaptotagmin I, a vesicle-associated protein, accelerated the activation kinetics indicating Ca(v)2.2 coupling to the vesicle. The unique modifications of Ca(v)1.2 and Ca(v)2.2 kinetics by syntaxin 1A, SNAP-25, and synaptotagmin combined implied excitosome formation, a primed fusion complex of the channel with synaptic proteins. The Ca(v)1.2 cytosolic domain LC753-893, acted as a dominant negative modulator, competitively inhibiting insulin release of channel-associated vesicles (CAV), the readily releasable pool of vesicles (RRP) in islet cells. A molecular mechanism is offered to explain fast secretion of vesicles tethered to SNAREs-associated Ca2+ channel. The tight arrangement facilitates the propagation of conformational changes induced during depolarization and Ca2+-binding at the channel, to the SNAREs to trigger secretion. The results imply a rapid Ca2+-dependent CAV (RRP) release, initiated by the binding of Ca2+ to the channel, upstream to intracellular Ca2+ sensor thus establishing the Ca2+ channel as the Ca2+ sensor of neurotransmitter release.