Munc13-1 acts as a priming factor for large dense-core vesicles in bovine chromaffin cells
Munc13-1 acts as a priming factor for large dense-core vesicles in bovine chromaffin cells
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DOI：
10.1093/emboj/19.14.3586
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发表时间：
2000-07-17
期刊：
影响因子：
11.4
通讯作者：
Rettig, J
中科院分区：
文献类型：
--
作者：
Ashery, U;Varoqueaux, F;Rettig, J
在嗜铬细胞的大致密核心囊泡（LDCVs），它可以被释放的简短，强烈的刺激代表只有一小部分的“形态对接”囊泡在质膜。为了研究Munc 13 - 1在LDCV胞吐中的作用，我们在嗜铬细胞中过表达Munc 13 - 1，并通过笼状钙的闪光光解刺激分泌。这两个组成部分的胞吐爆发，这代表了融合的释放能力囊泡，增加了三倍。代表囊泡成熟和随后的融合的持续组分也增加了相同的因子。然而，对第二次闪光的反应大大降低，表明释放能力囊泡的耗尽。由于对接囊泡的数量没有明显变化，我们得出结论，Munc 13 -1作为一个启动因子，通过加速从一个池的对接，但未引发囊泡的释放能力，引发囊泡池的囊泡转移的速率常数。
In chromaffin cells the number of large dense-core vesicles (LDCVs) which can be released by brief, intense stimuli represents only a small fraction of the 'morphologically docked' vesicles at the plasma membrane. Recently, it was shown that Munc13-1 is essential for a post-docking step of synaptic vesicle fusion, To investigate the role of Munc13-1 in LDCV exocytosis, we overexpressed Munc13-1 in chromaffin cells and stimulated secretion by flash photolysis of caged calcium. Both components of the exocytotic burst, which represent the fusion of release-competent vesicles, were increased by a factor of three. The sustained component, which represents vesicle maturation and subsequent fusion, was increased by the same factor. The response to a second flash, however, was greatly reduced, indicating a depletion of release-competent vesicles. Since there was no apparent change in the number of docked vesicles, we conclude that Munc13-1 acts as a priming factor by accelerating the rate constant of vesicle transfer from a pool of docked, but unprimed vesicles to a pool of release-competent, primed vesicles.