The Role of Lysosomal Glucocerebrosidase in Synucleinopathies

描述（由申请人提供）：突触核蛋白病，包括路易体痴呆（DLB）、多系统萎缩（MSA）和帕金森病（PD），是一组以α -突触核蛋白（a-syn）积累为特征的神经退行性疾病，α -突触核蛋白是一种小的神经特异性蛋白，异常聚集成淀粉样原纤维，构成路易体，突触核蛋白病的特征性病理包涵体。PD研究以及多个神经退行性疾病研究领域的关键问题之一是如何针对特定的毒性、致病性片段进行治疗开发。控制a-syn毒性形式形成的体内过程和细胞因素在很大程度上是未知的。戈谢病（GD）是一种罕见的溶酶体储存疾病，以编码葡萄糖脑苷酶（GC）酶的基因（GBA1）突变为特征，最近在戈谢病（GD）患者中发现帕金森病和路易体，这表明溶酶体鞘脂代谢与a-syn聚集之间存在联系。在我们的初步数据中，我们发现GCase的消耗导致GD小鼠和秀丽隐杆线虫模型的内源性a-syn积累和神经变性。神经元中GCase活性受损导致GCase底物葡萄糖神经酰胺的积累，溶酶体功能减弱，并增加具有神经毒性的可溶性a-syn低聚体中间体。重要的是，我们发现a-syn积累能够影响神经元和人脑中正常GCase的溶酶体成熟和活性，这表明glcer积累也在散发性PD和其他突触核蛋白病中发挥作用。本申请中提出的实验将进一步验证糖代谢改变参与突触核蛋白病发病机制的假设。我们将研究是否将突变或正常的葡萄糖脑苷酶靶向溶酶体，以防止或减少毒性α -突触核蛋白寡聚物的形成，并打破α -突触核蛋白聚集和毒性的恶性循环。如果成功，这些研究将进一步验证溶酶体GCase在突触核蛋白病中的作用，并为PD和以a-syn积累为特征的相关疾病的新疗法的开发确定一个特定的分子途径。

DESCRIPTION (provided by applicant): The synucleinopathies, including Dementia with Lewy bodies (DLB), Multiple system atrophy (MSA), and Parkinson's disease (PD), are a group of neurodegenerative disorders characterized by the accumulation of alpha-synuclein (a-syn), a small neural- specific protein that aberrantly aggregates into amyloid fibrils that comprise Lewy bodies, the characteristic pathological inclusions found in synucleinopathies. One of the critical issues in PD research, as well as across several neurodegenerative disease research areas, is how to target the specific toxic, pathogenic moiety for therapeutic development. The in vivo processes and cellular factors that control the formation of a-syn toxic forms are largely unknown. The recent discovery of parkinsonism and Lewy bodies in patients with Gaucher disease (GD), a rare lysosomal storage disorder characterized by mutations in the gene (GBA1) encoding glucocerebrosidase (GC)ase, suggests a link between lysosomal sphingolipid metabolism and a-syn aggregation. In our preliminary data we show that depletion of GCase results in endogenous a-syn accumulation and neurodegeneration in mouse and C. elegans models of GD. Compromised GCase activity in neurons led to accumulation of the GCase substrate glucosylceramide, diminished lysosomal function, and increased soluble a-syn oligomeric intermediates that were neurotoxic. Importantly, we found that a-syn accumulation has the ability to affect the lysosomal maturation and activity of normal GCase in neurons and human brain, suggesting that GlcCer accumulation also plays a role in sporadic PD and other synucleinopathies. The experiments proposed in this application will further test the hypothesis that alterations in GlcCer metabolism contribute to the pathogenesis of synucleinopathies. We will examine whether therapeutic targeting of mutated or normal glucocerebrosidase to lysosomes prevents or diminishes formation of toxic alpha- synuclein oligomers and breaks the vicious cycle of alpha-synuclein aggregation and toxicity. If successful, these studies will provide further validation for a role of lysosomal GCase in synucleinopathies and identify a specific molecular pathway for the development of new therapies for PD and related diseases characterized by accumulation of a-syn. PUBLIC HEALTH RELEVANCE: We propose to develop strategies to facilitate clearance of accumulated alpha-alpha- synuclein by targeting lysosomal enzyme glucocerebrosidase that is mutated in Gaucher disease (GD). Since clinical and genetic links between GD and parkinsonism have been established, our approach, if successful, should provide a specific molecular target for therapeutic development in parkinsonism and other synucleinopathies.