帕金森病（PD）是以α-synuclein清除障碍形成的路易小体和黑质多巴胺能神经元进行性死亡为病理学特征的疾病，但其分子机制尚不清楚。本项目应用定量蛋白组学检测早期PD转基因小鼠黑质蛋白表达及磷酸化与泛素化修饰水平，发现与自噬相关的C9orf72蛋白表达下降，修饰水平升高，C9orf72已被证实与渐冻症和额颞叶痴呆发病相关，但其在PD发病中的作用尚无报道。本项目拟深入探究C9orf72参与PD中自噬障碍和神经元死亡的分子机制：首先在PD临床标本和细胞/动物模型中检测C9orf72蛋白磷酸化和泛素化水平及降解情况和降解通路；然后研究PD时CDK5通过磷酸化C9orf72的S9位点介导其泛素化降解；继而探讨C9orf72降解参与α-synuclein自噬清除障碍和神经元死亡的机制；最后验证特异干预CDK5磷酸化C9orf72能否减轻PD中神经元死亡和运动障碍，为预防和早期治疗PD提供新靶点。

Parkinson disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), and by the presence of Lewy bodies (LBs) in this region, but the mechanism is still unclear. In the current study, we used quantitative proteomics to detect the protein expression and phosphorylation, ubiquitination levels in the SNpc of A30P*A53T α-synuclein transgenic mouse model of PD. We found that the expression of Chromosome 9 open reading frame 72 (C9orf72) decreased, phosphorylation and ubiquitination levels increased. C9orf72 has been demonstrated to be associated with the pathogenesis of amyotrophic lateral sclerosis and frontotemporal dementia, but its role in the pathogenesis of PD has not been reported. This project intends to explore the molecular mechanism of C9orf72 involvement in autophagy dysfunction and neuron death in PD. Firstly, the phosphorylation and ubiquitination levels of C9orf72 protein were detected in PD clinical specimens, cell and animal models. The molecular mechanism of C9orf72 degradation in neurons was analyzed. Secondly, We assumed that C9orf72 could phosphorylated by CDK5 at S9, consequently promote the ubiquitination and degradation of C9orf72. Thirdly, we investigated whether C9orf72 degradation is involved in the disorder of α-synuclein autophagy clearance and neuron death in PD. Finally, we verified whether interference of CDK5 phosphorylation of C9orf72 could alleviate autophagy dysfunction, reduce neuronal death and improve movement performance in the PD model, in order to provide a new idea and drug development target for PD research.