免疫蛋白酶体在帕金森病发生发展中的作用及分子机制探讨

Parkinson’s disease (PD) is a progressive neurodegenerative disorder involved in aging,genetic mutation,and environmen, degrading the accumulated alpha-synuclein(a-syn) and modulating the inflammatory process are critical in the disease progression. Immunoproteasome has multiple biological functions, including degrade misfolded proteins, anti-oxidative stress and modulate inflammation. Software predicted that a-syn could be degraded by immunoproteasome, then the interaction between a-syn and other proteins would be affected greatly. Besides, based on the PD animal and cellular models,we found the immunoproteasome and some inflammatory pathways were changed during the injury of dopaminergic neuron and activation of microglia.This study aims to confirm the expression,distribution and enzymatic activity of immunoproteasome,assess its degradation efficiency of accumulated a-syn,disclose its impact on mitochondrial function, oxidative stress, the content of dopamine, antigen presentation,NF-κB activation and the release of TNF-a,IL-1β,and IL-6, the findings may providesome novel therapeutic targets on PD.

帕金森病是遗传、衰老、环境毒素相互作用的结果，降解异常积聚的a-突触核蛋白，调控炎症反应是延缓疾病发生发展的关键。免疫蛋白酶体具有降解异常积聚蛋白、抗氧化应激、调节免疫应答等多种生物学功效，预测分析提示a-syn氨基酸序列存在免疫蛋白酶体作用点，断裂后显著影响它与胞膜、蛋白质相互作用，随后我们在帕病金森动物、细胞模型中发现多巴胺神经元损伤和小胶质细胞活化均伴随免疫蛋白酶体形成，炎症相关分子信号通路改变。本项目拟在前期基础上，通过药物/毒素干预、基因沉默/过表达等方法，明确免疫蛋白酶体的表达、活性变化及细胞分布特征，评估它对异常积聚a-syn的降解效率，对线粒体功能、氧化应激水平，多巴胺储量，HLA、NF-κB炎症相关信号通路及炎症因子TNF-a、IL-1B、IL-6释放的影响，揭示免疫蛋白酶体在帕金森病发生发展中的作用及分子机制，为治疗PD及延缓病程提供新方向。

帕金森病（Parkinson's disease, PD）典型运动障碍出现前10-20年，黑质多巴胺神经元（dopaminergic neuron, DAN）已大量变性并出现a-突触核蛋白（alpha-synuclein, α-syn) 异常积聚，同时伴小胶质细胞、T淋巴细胞激活。免疫蛋白酶体（Immunoproteasome, IP）具有降解错误折叠蛋白，抗氧化应激，调控炎症反应等多种生物学功效。前期研究中我们发现α-syn氨基酸序列内存在7个可能被IP切割的位点，PSMB9和HLA-II区域内存在PD的易感基因位点，提示IP及其下游的抗原呈递信号通路可能与PD发生发展有关。. 我们在PD大鼠和细胞模型中，应用神经毒素/药物、基因沉默/过表达等方法，发现：① 6-OHDA及rotenone在体内和体外模型中均可激活IP的β催化亚基(PSMB8/PSMB9/PSMB10)及下游的抗原呈递相关蛋白(TAP1,TAP2,MHC-1,MHC-II)。② IP与DAN和小胶质细胞均能共定位。③ 异常积聚的a-syn和IP 共定位。④ 抑制/过表达IP的β亚基(PSMB8/PSMB9)调节抗原呈递。⑤抑制IP的β亚基(PSMB8/PSMB9)会加剧神经毒素导致的氧化应激、线粒体损伤、a-syn积聚及DAN凋亡，过表达IP的β亚基则能减轻神经毒素的作用。. 以上结果说明IP参与了DAN的变性，它在抗氧化应激、保护线粒体、抑制蛋白异常积聚和调节抗原呈递过程中均起作用，有望成为新的神经保护作用靶点。