Alpha-Synuclein and the Synaptic Vesicle Cycle

摘要 大量证据表明，突触核蛋白与糖尿病的发病机制有关。 帕金森氏病(PD)。突触核蛋白的点突变可导致常染色体显性帕金森病， 散发性帕金森病的路易小体和营养不良的突起中有突触核蛋白积聚。 这表明这种蛋白质在大多数形式的疾病中都起到了作用。重要的是，剂量的增加 野生型基因的突变也可以引起帕金森病，这表明正常蛋白和 或许这是它的正常功能。突触核蛋白在帕金森病中的作用及其正常功能 人们对此仍然知之甚少。 对酵母和哺乳动物系统的研究表明，突触核蛋白在 膜贩子。该蛋白质在体外与膜相互作用，主要定位于 轴突在神经元中的终末，但它对突触囊泡的胞吐和循环的影响仍然存在 备受争议且知之甚少。这项建议的长期目标是澄清 突触核蛋白在神经末梢的生理相关功能。自PD以来 似乎涉及到突触核蛋白的增加，策略一直是过度表达蛋白质 并用光学方法评价其对突触囊泡周期的影响 活细胞的成像。 在使用光学成像、电生理学、 生化和电子显微镜下，我们发现突触核蛋白的过度表达 通过减小突触小泡回收池的大小来损害神经递质的释放， 为它在神经元中的作用提供了一些首批明确的证据。我们现建议： 1)确定突触核蛋白对递质释放的抑制是否涉及其 正常功能，通过研究三重突触核蛋白基因敲除小鼠；2)表征？ 突触核蛋白对突触小泡蛋白和膜的分散和再聚集的影响 3)评估突触中突触蛋白、突触蛋白和突触亲和素之间的关系 以及4)确定突触核蛋白对神经递质的影响 释放会导致退化。 这些结果将把之前关于突触核蛋白的工作扩展到它在 并为理解？-的功能提供了一个重要的生理框架。 突触核蛋白。在这个过程中，他们将解决可能导致退化的机制 在帕金森氏病中观察，并提出逆转功能的治疗策略 由于存活的神经元释放递质受损所致的残疾。

Abstract Considerable evidence has implicated the protein ¿-synuclein in the pathogenesis of Parkinson's disease (PD). Point mutations in ¿-synuclein can cause autosomal dominant PD, and ¿-synuclein accumulates in the Lewy bodies and dystrophic neurites of sporadic PD, suggesting a role for the protein in most forms of the disorder. Importantly, an increased dose of the wild type gene can also cause PD, indicating a pathogenic role for the normal protein and perhaps its normal function. However, the role of ¿-synuclein in PD and its normal function remain poorly understood. Studies in yeast and mammalian systems have suggested a role for ¿-synuclein in membrane trafficking. The protein interacts with membranes in vitro and localizes primarily to the axon terminal in neurons, but its effects on synaptic vesicle exocytosis and recycling remain controversial and poorly understood. The long-term objective of this proposal is to elucidate the function of ¿-synuclein in its physiologically relevant context, at the nerve terminal. Since PD seems to involve an increase in ¿-synuclein, the strategy has been to over-express the protein in primary neuronal culture, and assess its effects on the synaptic vesicle cycle by optical imaging of live cells. In preliminary experiments using a combination of optical imaging, electrophysiology, biochemistry and electron microscopy, we have found that over-expression of ¿-synuclein impairs neurotransmitter release by reducing the size of the synaptic vesicle recycling pool, providing some of the first unambiguous evidence for its role in neurons. We now propose to: 1) determine whether the inhibition of transmitter release by synuclein involves a gain in its normal function, by studying triple synuclein knock-out mice; 2) characterize the effect of ¿- synuclein on dispersion and reclustering of synaptic vesicle protein and membrane after exocytosis; 3) assess the relationship between synuclein, synapsins and synphilin in synaptic vesicle mobilization; and 4) determine whether the effects of synuclein on neurotransmitter release contribute to degeneration. The results will extend previous work on ¿-synuclein to its appropriate biological context in neurons, and provide a crucial physiological framework to understand the function of ¿- synuclein. In the process, they will address a mechanism that may give rise to the degeneration observed in Parkinson's disease, and suggest therapeutic strategies to reverse functional disability due to the impaired release of transmitter from neurons that survive.