Mechanisms of Endosomal Dysfunction at Synapses in A-Synuclein Pathology

摘要/总结 突触核蛋白病，包括帕金森病（PD）和路易体痴呆（DLB），是一种常见的神经系统疾病。 以α-突触核蛋白异常聚集为特征的神经变性疾病。此外， 已知α-突触核蛋白以多种结构形式存在（即，单体和低聚物）， 不同机制的神经毒性。虽然有大量证据表明α-突触核蛋白的积累 广泛损害突触囊泡内吞作用，不同α-突触核蛋白种类对突触内体的影响 贩运活动基本上是未知的。拟议的研究将是第一个详细调查积累如何 不同的寡聚体α-突触核蛋白种类影响脊椎动物突触的内体运输， 潜在的细胞和分子机制。使用七鳃鳗突触模型，一种经典的脊椎动物 通过这个模型，我们可以将精确数量的纯化β-突触核蛋白直接递送到突触中。这使我们能够 独立测试不同的β-突触核蛋白种类对突触前超微结构和功能的影响。我们 初步研究表明，过量的单体β-突触核蛋白损害内体运输，如a 突触囊泡数量减少，伴随着非典型大囊泡数量增加， 让人想起内体。这为拟议的研究提供了一个很好的模型。在目标1（K99）中，我们将 确定单体人类β-突触核蛋白如何影响突触内体运输。在目标2（R 00）中，我们 将确定寡聚体人β-突触核蛋白如何促进β-突触核蛋白介导的内体功能障碍， 突触重点将放在不同的寡聚体β-突触核蛋白种类，包括二聚体，小寡聚体和 来自PD/DLB人脑的较大寡聚体。这些研究将提供关键的理解， 开发用于改善突触核蛋白病中突触功能的疗法。

ABSTRACT/SUMMARY Synucleinopathies, including Parkinson’s disease (PD) and Dementia with Lewy Bodies (DLB), are neurodegenerative diseases characterized by the abnormal aggregation of α-synuclein. Furthermore, it is well known that α-synuclein exists in multiple structural forms (i.e., monomers and oligomers) that contribute to neurotoxicity by distinct mechanisms. While there is substantial evidence that accumulation of α-synuclein broadly impairs synaptic vesicle endocytosis, the effects of distinct α-synuclein species on synaptic endosomal trafficking are largely unknown. The proposed studies will be the first to investigate in detail how accumulation of different oligomeric α-synuclein species affect endosomal trafficking at vertebrate synapses and the underlying cellular and molecular mechanisms. Using the lamprey synapse model, a classical vertebrate model, we can deliver precise amounts of purified -synuclein species directly into synapses. This allows us to independently test the effects of different -synuclein species on presynaptic ultrastructure and function. Our preliminary studies suggest that excess monomeric -synuclein impairs endosomal trafficking, as shown by a reduction in the number of synaptic vesicles and concomitant increase in the number of atypical large vesicles, reminiscent of endosomes. This provides an excellent model for the proposed studies. In Aim 1 (K99), we will determine how monomeric human -synuclein affects endosomal trafficking at synapses. In Aim 2 (R00), we will determine how oligomeric human -synuclein contribute to -synuclein-mediated endosomal dysfunction at synapses. The focus will be on different oligomeric -synuclein species including dimers, small oligomers and larger oligomers from PD/DLB human brains. These studies will provide critical understanding for the development of therapies for improving synaptic function in synucleinopathies.