Vesicle reuse revisited.
Vesicle reuse revisited.
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重新审视囊泡的再利用。
DOI：
10.1073/pnas.0502910102
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Zenisek,David
中科院分区：
文献类型：
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作者：
Zenisek,David
神经元通过从突触囊泡释放神经递质在突触处进行通信。胞吐作用后，突触囊泡膜和蛋白质在突触前末梢局部回收再利用。参与突触囊泡物质循环的机制尚未完全解决（参考文献1）。囊泡再循环的传统模型假定囊泡与质膜合并，然后通过内吞作用在突触周围区域回收（2-4）。第二个模型，通常被称为“吻和跑”（5），表明神经递质通过融合孔释放，允许囊泡释放神经递质，同时保留其蛋白质和/或脂质（6）。通过重新填充神经递质，以这种方式形成的囊泡可能会迅速被重复使用。在大鼠海马神经元中发现了突触囊泡快速再利用的证据（7，8），但这种机制对池再循环的贡献仍有争议。李等人的工作。(9)在最近一期的《美国国家科学院院刊》中，为这场辩论引入了新的工具和新的数据。Thy-1突触荧光蛋白小鼠：一种新的突触传递可视化工具(9)为神经生物学家研究突触传递开发了一种新的工具。作者利用了突触荧光蛋白（10），一种突触囊泡蛋白（突触泡蛋白），在其管腔侧与pH敏感的GFP连接。pHluorin在酸性条件下表现出最小的荧光，并且由于分泌囊泡保持酸性内部，携带突触Hluorin的囊泡的胞吐作用由荧光突然变亮指示，并且随着新形成的细胞器酸化，发射信号变暗指示囊泡成分的回收（11）。这种可视化胞吐作用的技术首先由Miesenbock及其同事开发（10），已被神经生物学家用于研究培养神经元中胞吐作用和内吞作用的特性（11，12）。先前的研究已经在原代细胞培养物中瞬时过表达synaptopHluorins;然而，该方法是繁琐的，并且提供很少或没有机会用于给定细胞类型的选择性标记。Li等人的方法学进展是产生了12系转基因小鼠，其中脑中的突触荧光蛋白表达是由thy-1 pro-fos驱动的。
Neurons communicate at the synapse by releasing neuro-transmitter from synaptic vesicles. After exocytosis, synaptic vesicle membrane and protein are locally recycled for reuse in the presynaptic terminal. The mechanisms involved in the recycling of synaptic vesicle material have yet to be fully resolved (reviewed in ref. 1). The traditional model of vesicle recycling posits that vesicles merge with the plasma membrane and then are later retrieved in perisynaptic regions by endocytosis (2–4). A second model, often referred to as ‘‘kiss-and-run’’(5), suggests that neurotransmitter is released through a fusion pore that allows the vesicle to release neurotransmitter while retaining its protein and/or lipid (6). By refilling with neurotransmitter, vesicles formed in this manner could potentially become rapidly available for reuse. Evidence for rapid reuse of synaptic vesicles has been found in rat hippocampal neurons (7, 8), yet the contribution of this mechanism to pool recycling remains debated. The work by Li et al.(9) in a recent issue of PNAS introduced new tools and new data to this debate. thy-1 SynaptopHluorin Mice: A New Tool for Visualizing Synaptic TransmissionLi et al.(9) develop a new tool for neurobiologists to exploit in their study of synaptic transmission. The authors make use of synaptopHluorin (10), a synaptic vesicle protein (synaptobrevin) that has been concatenated with a pH-sensitive GFP on its luminal side. pHluorin exhibits minimal fluorescence under acidic conditions and because secretory vesicles maintain an acidic interior, exocytosis of vesicles carrying synaptopHluorin is indicated by an abrupt brightening in fluorescence, and the retrieval of vesicle constituents is indicated by a dimming in the emission signal as newly formed organelles acidify (11). This technique for visualizing exocytosis, first developed by Miesenbock and colleagues (10), has been used by neurobiologists to study properties of exocytosis and endocytosis in cultured neurons (11, 12). Previous studies have transiently overexpressed synaptopHluorins in primary cell cultures; however, the method is cumbersome and offers little or no opportunity for selective label of a given cell type. The methodological advance by Li et al. is the generation of 12 lines of transgenic mice in which synaptopHluorin expression in the brain is driven by the thy-1 pro-