Regulation of LRRK2 in lysosomal stress response

帕金森病选择性神经退行性变的病理生理学基础仍存在争议。最近的遗传和生化分析发现LRRK2激酶活性异常是晚发性帕金森病(PD)的显著特征，既有家族性的也有特发性的。家族性LRRK2突变通常与激酶活性升高有关。识别调节LRRK2激酶的病理生理过程可以提供 这是了解帕金森病独特发病机制的关键窗口。LRRK2在溶酶体应激物、氯喹(CO)和LLOMe诱导的扩大的溶酶体上被招募和激活。我们假设，LRRK2募集到应激的溶酶体是溶酶体应激反应的一部分，其作用是使溶酶体返回到基础状态。LRRK2与应激溶酶体的关联通常是短暂的，在PD相关的VPS35-D620N突变细胞中，LRRK2与应激溶酶体的关联显著增强。这一发现表明，在VPS35-D620N细胞中，LRRK2被溶酶体应激过度激活。因此，应激诱导的LRRK2-溶酶体 关联和激活受到严格的调控，这种调控被导致家族性帕金森病的突变所破坏。对LRRK2-溶酶体协会的其他调节因子进行的一个小的聚焦化学抑制物筛选发现了PKD。与LRRK2类似，PKD被溶酶体应激激活，而其失活则导致LRRK2与溶酶体的异常结合和激活。本研究旨在确定将LRRK2招募到应激溶酶体内的分子实体，并表征PKD信号通路在LRRK2激活和致病毒性中的作用。这一建议的完成可能提供致病LRRK2激活的生化机制，确认PKD是LRRK2的新调节因子，并确定溶酶体应激是迟发性PD的病理生理触发因素

The pathophysiological basis of selective neurodegeneration in Parkinson's disease remains controversial. Recent genetic and biochemical analyses have uncovered aberrant LRRK2 kinase activity as a salient feature of late-onset Parkinson's disease (PD) of both familial and idiopathic origin. Familial LRRK2 mutations are generally associated with elevated kinase activity. Identifying the pathophysiological processes that regulate LRRK2 kinase could provide a critical window to understand the pathogenesis unique to PD. LRRK2 is recruited and activated at enlarged lysosomes induced by lysosome stressors, chloroquine (CO) and LLOMe. We hypothesize that LRRK2 recruitment to the stressed lysosome is part of the lysosome stress response that acts to return lysosome to the basal states. LRRK2 association with stressed lysosomes is typically transient Remarkably, the LRRK2 association with stressed lysosomes becomes dramatically enhanced in PD-associated Vps35-D620N mutant cells. This finding suggests that LRRK2 becomes excessively activated by the lysosomal stress in Vps35-D620N cells. Thus, stress-induced LRRK2-lysosome association and activation are tightly regulated, and this regulation is disrupted by a mutation that causes familial PD. A small focused chemical inhibitor screen for additional regulators of LRRK2-lysosome association identified PKD. PKD, similar to LRRK2, is activated by lysosomal stresses, while its inactivation led to aberrant LRRK2-lysosome association and activation. This proposal aims to identify the molecular entity that recruits LRRK2 to stressed lysosomes and characterize the role of PKD-signaling pathway in LRRK2 activation and pathogenic toxicity. This proposal's completion could provide a biochemical mechanism underlying pathogenic LRRK2 activation, identify PKD as a novel regulator of LRRK2, and ascertain lysosomal stress as a pathophysiological trigger to late-onset PD