The Role of Lysosomal Dysfunction in Parkinson Disease-Related Neurodegeneration

描述（由申请人提供）：为了保持健康，神经元必须及时清除错误折叠或突变的蛋白质，利用几种蛋白质降解途径。自噬-溶酶体系统允许细胞质蛋白被运输到特定的细胞器中，在那里它们被溶酶体蛋白酶降解。自噬缺陷与包括帕金森病（PD）在内的许多神经退行性疾病有关。α -突触核蛋白是PD中聚集的关键蛋白，可通过自噬降解，并且几种溶酶体酶的突变与家族性帕金森病有关。最近的工作集中在GBA（编码溶酶体糖脑苷酶的基因）的缺失和戈谢病的缺乏如何导致PD风险增加。ATP13A2（一种溶酶体atp酶）的缺失同样会导致家族性帕金森病，可能是通过改变自噬。本提案的目的是确定溶酶体ATP13A2的缺失如何导致自噬缺陷和PD的发病机制。我开发了一种新的PD小鼠模型，其中内源性Atp13a2的缺失导致与年龄相关的运动异常和神经病理。为了更好地理解这些缺陷的机制，我将测试Atp13a2缺失导致自噬-溶酶体系统损伤的特定假设，这反过来导致蛋白质聚集、神经元功能障碍和运动缺陷。我将提出这一假设有两个目的：1)从超微结构上确定Atp13a2缺失如何改变自噬-溶酶体系统中的中间体；2)确定Atp13a2缺失小鼠中溶酶体积累和蛋白质聚集的顺序和时间。在Aim 1下，我将使用电子显微镜来确定野生型和Atp13a2缺失小鼠中特异性自噬中间体的相对丰度。在Aim 2下，我将评估不同年龄的Atp13a2缺失和野生型小鼠，以确定蛋白质聚集、溶酶体积累和α -突触核蛋白不溶性的开始。本提案中概述的实验有望为溶酶体中ATP13A2的功能以及ATP13A2的缺失如何导致KRD提供基础知识。这些结果将有助于更广泛地了解溶酶体在帕金森病发病机制中的作用。

DESCRIPTION (provided by applicant): To maintain health, neurons must clear misfolded or mutant proteins in a timely manner, utilizing several pathways for protein degradation. The autophagic-lysosomal system allows cytosolic proteins to be trafficked into specific organelles where they are degraded by lysosomal proteases. Deficits in autophagy have been implicated in many neurodegenerative disorders including Parkinson disease (PD). Alpha-synuclein, a key protein that aggregates in PD, is degraded by autophagy and mutations in several lysosomal enzymes have been linked to familial forms of Parkinsonism. Recent work has focused on how loss of GBA, the gene encoding lysosomal glucocerebrosidase and deficient in Gaucher's disease, leads to an increased risk of PD. Loss of ATP13A2, a lysosomal ATPase, similarly results in a familial form of Parkinsonism, likely through alterations to autophagy. The objective of this proposal is to determine how loss of lysosomal ATP13A2 results in autophagic deficits and PD pathogenesis. I have developed a novel mouse model of PD in which loss of endogenous Atp13a2 results in age-related motor abnormalities and neuropathology. To better understand the mechanism underlying these deficits, I will test the specific hypothesis that loss of Atp13a2 results in impairment of the autophagic-lysosomal system, which in turn causes protein aggregation, neuronal dysfunction, and motor deficits. I will develop this hypothesis with two aims: 1) Determine ultrastructurally how loss of Atp13a2 alters intermediates in the autophagic-lysosomal system and 2) Determine the sequence and timing of lysosome accumulation and protein aggregation in Atp13a2 null mice. Under Aim 1, I will use electron microscopy to determine the relative abundance of specific autophagic intermediates in wildtype and Atp13a2 null mice. Under Aim 2, I will assess Atp13a2 null and wildtype mice at different ages to determine the onset of protein aggregation, lysosomal accumulation, and alpha-synuclein insolubility. The experiments outlined in this proposal are expected to contribute fundamental knowledge to the function of ATP13A2 within the lysosome, as well as how loss of ATP13A2 results in KRD. These results will contribute more broadly to understanding the role of the lysosome in PD pathogenesis.