帕金森病相关蛋白LRRK2调控Rho GTPases信号通路促进吞噬α-synuclein寡聚体介导的小胶质细胞活化

Leucine-rich repeat kinase 2（LRRK2）is an important pathogenic gene in Parkinson's disease (PD), however the role of LRRK2 in the pathogenic mechanisms of PD is still unclear. Our previous studies have shown that a large number of α-synuclein-positive inclusions were detected in the microglia incubated by PD patients' cerebrospinal fluids(CSF), and found theα-synuclein oligomers phagocytosis can induce the activation of microglia. Further studies have shown LRRK2 enhanced cell phagocytosis by positive regulation of Rho GTPase activity. These results suggest that LRRK2 may promote microglial phagocytosis of α-synuclein oligomers through activation of Rho GTPases signaling pathway. This study intends to investigate the molecular mechanism of LRRK2 promoting microglial phagocytosis ofα-synuclein oligomers through activation of Rho GTPases signaling pathway, and further determine the regulation of LRRK2 in microglia activation and neuron damage in the animal model. We intend to use α-synuclein oligomers mediated microglia activation as the entry point to explore the pathogenic mechanism of LRRK2 in PD from a new perspective.

LRRK2是帕金森病（PD）的重要致病基因，然而其致病机制尚不清楚。我们前期研究在PD患者脑积液（PD-CSF）培养的小胶质细胞中检测到大量α-synuclein阳性包涵体的形成，并发现吞噬α-synuclein寡聚体能够诱导小胶质细胞活化。进一步研究表明LRRK2做为Rho GTPase的活化因子参与调控细胞吞噬，在PD-CSF诱导活化的小胶质细胞中大量表达。上述研究提示LRRK2可能通过激活Rho GTPases通路，促进小胶质细胞吞噬α-synuclein寡聚体，而诱导其活化。本研究拟在细胞水平阐明LRRK2调控Rho GTPases促进吞噬α-synuclein介导的小胶质细胞活化的分子机制。并在动物模型中验证LRRK2激活小胶质细胞诱导神经元损伤的病理过程。试图以吞噬α-synuclein寡聚体介导的小胶质细胞活化为切入点，从一个全新的角度探索LRRK2的致病机理。

异常的蛋白聚集物—“包涵体”已经成为神经退行性疾病的病理标志。帕金森病(Parkinson’s disease，PD)病理机制是α-突触核蛋白(α-synuclein，α-Syn)阳性包涵体—路易小体形成及在中枢神经系统中播散。研究表明小胶质细胞活化与“包涵体”的形成及其在细胞间的播散密切相关。因此，筛选小胶质细胞活化调控因子将为延缓PD病程进展提供新的干预靶点。本研究运用质粒转染、细胞免疫荧光、流式细胞技术、免疫共沉淀、细胞模型及转基因小鼠模型等方法证实：PD患者脑脊液培养的小胶质细胞内α-Syn阳性包涵体增多、细胞活化并损伤神经元。在α-Syn寡聚体诱导小胶质细胞活化细胞模型中，LRRK2通过活化Rho GTPases信号通路，增强α-Syn寡聚体的胞吞，诱导小胶质细胞活化，导致神经元损伤。在α-Syn转基因鼠模型中，脑组织小胶质细胞中α-Syn、LRRK2、Rho GTPases、CD11b及多巴胺能神经元中TH的表达上调。此结果证实LRRK2激活Rho GTPases信号通路，通过增强小胶质细胞对α-Syn寡聚体的吞噬，诱导小胶质细胞活化并损伤神经元，而在PD进展中发挥作用。因此调控LRRK2在体内的表达水平将有助于抑制PD中路易小体的形成及播散。