死亡相关蛋白激酶-1在MPTP帕金森病小鼠认知功能损害中的作用研究

Cognitive impairment is a common non-motor symptom in Parkinson’s disease, which can present as dementia in advanced stage. Pathogenesis of Parkinson’s disease dementia（PDD）is still not clear. Our previous study found that cognitive impairment appeared and the death-associated protein kinase 1 (DAPK1) activity in striatum increased in MPTP-induced Parkinson model mice. According to increased phosphorylation level of α-synuclein and tau protein, and identified results DAPK1 promote α-synuclein phosphorylation at Ser129 in vitro, we speculate that DAPK1 promote tau protein phosphorylation and aggregation by increasing the level of phosphorylation of α-synuclein, which in turn affect synaptic function. The pathway plays a dominant role in cognitive impairment in MPTP-induced Parkinson model mice. In present study, we will make MPTP-induced Parkinson model mice using DAPK1-/ - mice and lentiviral vector-mediated striatal gene silencing α-synuclein mice, respectively. We will verify the above inference, by testing cognitive behavior, measuring electrophysiology of brain slice, testing changes of phosphorylation and protein aggregation of α-synuclein and tau protein in striatum, and testing changes of synaptic plasticity in striatum in the two different models.

认知功能障碍是帕金森病常见的非运动症状，晚期可发展为帕金森病痴呆（PDD）。PDD的发病机制不明。本课题组前期研究发现MPTP诱导的PD小鼠出现认知障碍并伴有纹状体区死亡相关蛋白激酶1（DAPK1）活性升高、α-synuclein与tau蛋白磷酸化水平上升，且体外试验证实DAPK1可促进α-synuclein Ser129位点磷酸化。我们推测：DAPK1通过提高α-synuclein 磷酸化水平促进tau蛋白磷酸化及蛋白聚集，继而影响突触功能，该作用途径在MPTP诱导PD小鼠认知损害的发生中起主导作用。为此本研究拟利用DAPK1-/-小鼠和慢病毒载体介导的纹状体α-synuclein基因沉默小鼠分别制作MPTP诱发PD模型，通过比较不同模型间的认知行为学及脑片电生理测定结果、纹状体区α-synuclein与tau蛋白磷酸化及其蛋白聚集的变化，以及纹状体区突触可塑性的改变，验证上述推断。

本研究项目通过离体细胞、PD小鼠动物模型以及PD患者脑脊液多个不同层次分别阐述了DAPK1蛋白激活在PD认知障碍中的作用。研究结果发现PD小鼠出现运动及认知功能损害，且PD小鼠脑内DAPK1蛋白水平升高，并且与突触核蛋白磷酸化水平及聚集程度成正相关。体外试验发现DAPK1激活后可以直接诱导突触核蛋白Ser129位点磷酸化，从而促进突触核蛋白病理学改变。而DAPK1蛋白水平升高是由于mir-26a下调诱导DAPK1转录后蛋白表达增高所致，并且动物实验证实mir-26a丢失或DAPK1上调可以诱导PD样病理学改变和行为学改变。相反上调mir-26a水平或抑制DAPK1表达，则可改善PD样病理学变化及动物行为学变化。.本项目研究结果为临床PD及PD认知障碍的药物治疗提供新的靶点及实验依据。