The role of a-synuclein accumulation in lysosomal hydrolase trafficking and function

 描述(申请人提供)：蛋白质堆积是所有与年龄相关的神经退行性疾病的一个有充分证据的特征，但导致其形成的起始事件及其与疾病的关系仍不清楚。帕金森氏病(PD)的特征是一种名为a-突触蛋白的正常可溶性突触蛋白转化为不可溶的淀粉样纤维，其中包括帕金森脑内的路易小体包涵体。我们最近的数据表明，溶酶体基因GBA1的突变破坏了细胞的降解能力，导致了α-突触核蛋白的聚集。这表明溶酶体功能的破坏有助于路易小体的形成。有趣的是，我们发现当α-突触核蛋白积累时，它可以反过来反馈抑制溶酶体系统，从而导致一个自我传播的循环，促进神经元内淀粉样蛋白的形成和生长。我们的初步数据表明，α-突触核蛋白抑制了水解酶的运输，并阻止它们到达溶酶体室；然而，其分子机制尚不清楚。本申请中概述的实验旨在描述a-syn如何使用细胞系、帕金森病患者诱导的多能干细胞模型、转基因小鼠和帕金森病脑来破坏溶酶体。我们的目标是1)明确不同的a-syn聚集体与溶酶体功能障碍/神经毒性之间的关系，2)确定a-syn如何影响溶酶体水解酶的蛋白运输，3)发现以促进水解酶折叠和运输到溶酶体为中心的帕金森病新的救援途径。这些研究将为淀粉样蛋白聚集如何扰乱细胞过程提供新的见解，并确定以增强溶酶体清除途径为中心的突触核病的新治疗途径。

 DESCRIPTION (provided by applicant): Protein accumulation is a soundly documented feature of all age-related neurodegenerative disorders, however the initiating events that lead to their formation, as well as their relationship to disease, remains unknown. Parkinson's disease (PD) is characterized by the conversion of a normally soluble synaptic protein called a-synuclein into insoluble amyloid fibrils that comprise Lewy body inclusions within Parkinson's brain. Our recent data indicated that disruption of cellular degradation capacity through mutations in the lysosomal gene GBA1 contribute to the aggregation of a-synuclein. This suggested that disruption of lysosomal function contributes to the formation of Lewy bodies. Interestingly, we found that when a-synuclein accumulates, it can in turn feedback to inhibit the lysosomal system, thus causing a self-propagating cycle that promotes amyloid formation and growth within neurons. Our preliminary data indicate that a-synuclein inhibits the trafficking of hydrolases and prevents them from reaching the lysosomal compartment; however the molecular mechanism is not known. Experiments outlined in this application aim to delineate how a-syn disrupts lysosomes using cell lines, PD patient-derived induced pluripotent stem cell models, transgenic mice, and PD brain. Our goals are to 1) define the relationship between distinct a-syn aggregated assemblies and lysosomal dysfunction / neurotoxicity, 2) determine how a-syn affects protein trafficking of lysosomal hydrolases, 3) discover new rescue pathways in PD centered around promoting hydrolase folding and trafficking to the lysosome. These studies will provide new insight into the mechanism of how amyloid aggregates disrupt cellular processes, and identify novel therapeutic pathways for synucleinopathies centered on enhancement of the lysosomal clearance pathway.