Modulating vesicle priming reveals that vesicle immobilization is necessary but not sufficient for fusion-competence.
Modulating vesicle priming reveals that vesicle immobilization is necessary but not sufficient for fusion-competence.
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DOI：
10.1371/journal.pone.0002694
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发表时间：
2008-07-16
期刊：
影响因子：
3.7
通讯作者：
Ashery, Uri
中科院分区：
文献类型：
--
作者：
Yizhar, Ofer;Ashery, Uri
在神经元和神经内分泌细胞中，停靠的小泡需要经过启动才能具有融合能力。启动是一个多步骤的过程，被证明与囊泡固定有关。然而，目前尚不清楚囊泡固定化是否足以获得完全的融合能力。为了扩大我们对囊泡启动的物理表现的理解，我们利用了一种特异性抑制囊泡启动的圈套相关蛋白Tomosyn，并利用全内反射荧光显微镜测量了它对活嗜铬细胞囊泡动力学的影响。我们在这里表明，在对照细胞中，囊泡在融合前经历固定化，而在Tomosyn过度表达的细胞中，囊泡固定化减弱。这反过来又增加了膜附近小泡的周转率，并减弱了新来的小泡的融合。此外，Tomosyn细胞中固定小泡的释放几率显著降低，这表明固定化是启动的早期和必要的步骤，但还不够，因为需要进一步的分子过程才能获得完全的融合能力。使用Tomosyn作为分子工具，我们提供了功能对接和启动之间的机械联系，并建议功能对接是囊泡启动的第一步，随后是不会转化为囊泡流动性变化的分子修饰。
In neurons and neuroendocrine cells, docked vesicles need to undergo priming to become fusion competent. Priming is a multi-step process that was shown to be associated with vesicle immobilization. However, it is not known whether vesicle immobilization is sufficient to acquire complete fusion competence. To extend our understanding of the physical manifestation of vesicle priming, we took advantage of tomosyn, a SNARE-related protein that specifically inhibits vesicle priming, and measured its effect on vesicle dynamics in live chromaffin cells using total internal reflection fluorescence microscopy. We show here that while in control cells vesicles undergo immobilization before fusion, vesicle immobilization is attenuated in tomosyn overexpressing cells. This in turn increases the turnover rate of vesicles near the membrane and attenuates the fusion of newcomer vesicles. Moreover, the release probability of immobile vesicles in tomosyn cells is significantly reduced, suggesting that immobilization is an early and necessary step in priming but is insufficient, as further molecular processes are needed to acquire complete fusion competence. Using tomosyn as a molecular tool we provide a mechanistic link between functional docking and priming and suggest that functional docking is the first step in vesicle priming, followed by molecular modifications that do not translate into changes in vesicle mobility.
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影响因子：
7.8
作者：
Johns, L M;Levitan, E S;Shelden, E A;Holz, R W;Axelrod, D
通讯作者：
Axelrod, D
DOI：
10.1083/jcb.200504055
发表时间：
2005-09-26
期刊：
The Journal of cell biology
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