Molecular Mechanism of LRRK2 Biology and Pathology in Parkinson's Disease

描述（由申请人提供）：本次更新R 01的总体目标是促进我们对富含亮氨酸重复激酶2（LRRK 2）的生物学和病理学的理解，LRRK 2的突变是帕金森病（PD）最常见的遗传原因。LRRK 2编码一个大而复杂的蛋白质（285 kD），包括一个激酶和一个GT3结构域。先前的多条证据导致了“功能获得性”假说，即LRRK 2致病性突变导致激酶活性增加，这可归因于神经毒性。最近在细胞培养中的研究暗示LRRK 2参与囊泡运输、神经突生长、细胞骨架动力学、蛋白质翻译和降解、线粒体动力学和炎症反应。重要的是，对遗传动物模型的研究表明，致病性LRRK 2突变损害多巴胺传递而不引起神经变性，这表明LRRK 2在神经变性之前的早期疾病阶段在神经传递中的病理生理作用。新出现的证据也将LRRK 2与神经炎症联系起来，这是PD神经变性的一个促成因素。但LRRK 2突变体介导神经功能障碍和神经毒性的确切机制尚不清楚。因此，我们假设：（1）LRRK 2调节SV蛋白功能和神经传递受损的LRRK 2致病性突变; 2）LRRK 2在神经胶质细胞的神经炎症反应中发挥关键作用; LRRK 2突变体解除神经胶质炎症通路的调节，并导致PD的神经毒性。我们的具体目标是：（1）确定LRRK 2在SV运输和神经传递中的致病作用;（2）检查LRRK 2在胶质神经炎症反应中的功能障碍。LRRK 2研究的一个主要挑战是缺乏与PD发病机制相关的LRRK 2的明确定义的神经变性模型。事实上，常见突变G2019 S的不完全疾病转移率表明环境因素对PD发病机制的重要贡献。我们的第三个目的是在动物模型中验证LRRK 2通过遗传病变和环境毒素相关的神经炎症引起PD神经变性的假设。该研究的成功完成不仅将深入了解LRRK 2生物学和病理生理学，而且还将提供有价值的细胞和动物模型，用于询问PD中的神经退行性通路，并开发LRRK 2抑制剂筛选平台。

DESCRIPTION (provided by applicant): The overarching goal of this renewal R01 is to advance our understanding of the biology and pathology of Leucine-Rich Repeat Kinase 2 (LRRK2), whose mutations are the most common genetic cause of Parkinson's disease (PD). LRRK2 encodes a large and complex protein (285kD) including a kinase and a GTPase domain. Previously multiple lines of evidence have led to a "gain-of-function" hypothesis that LRRK2 pathogenic mutations cause increased kinase activity that is attributable to the neurotoxicity. Recent studies in cell cultures implicate LRRK2 in vesicle trafficking, neurite outgrowth, cytoskeletal dynamics, protein translation and degradation, mitochondria dynamics and inflammatory response. Importantly, the study of genetic animal models show that the pathogenic LRRK2 mutations impair dopamine transmission without causing neurodegeneration, suggesting a pathophysiological role of LRRK2 in neurotransmission at early disease stage prior to neurodegeneration. Emerging evidence has also linked LRRK2 to neuroinflammation that is a contributing factor to neurodegeneration in PD. But the precise mechanisms whereby LRRK2 mutant mediate the neural dysfunction and neurotoxicity remain unclear. Therefore, we hypothesize that (1) LRRK2 regulates SV protein functions and neurotransmission that is impaired by LRRK2 pathogenic mutations; 2) LRRK2 plays a critical role in neuroinflammatory response in glial cells; LRRK2 mutants deregulate glial inflammatory pathway and cause neurotoxicity in PD. Our specific aims are to (1) determine the pathogenic role of LRRK2 in SV traffic and neurotransmission; (2) examine dysfunctional LRRK2 in glial neuroinflammatory response. A major challenge of LRRK2 research is the lack of well-defined neurodegeneration models of LRRK2 that are relevant to the PD pathogenesis. In fact, the incomplete disease penetrance of the common mutation G2019S suggests a significant contribution of environmental factors to PD pathogenesis. Our third aim is then to test the hypothesis in animal models that LRRK2 causes neurodegeneration in PD through genetic lesion and environmental toxin-linked neuroinflammation. Successful completion of the study not only will gain insight into LRRK2 biology and pathophysiology, but also will deliver valuable cell and animal models for interrogating neurodegenerative pathways in PD and developing platforms for LRRK2 inhibitor screening.