Nur77通过p53-AMPK介导的自噬调控在帕金森病中的作用机制研究

Parkinson's Disease (PD) is one of the most severe neurodegenerative disorders. Several lines of studies have shown that the dysfunction of autophagy plays important roles in the pathogenesis of PD. Our previous studies showed that in 6-OHDA-lesioned PC12 cells, a widely accepted and stable in vitro PD model, the expression of orphan nuclear receptor Nur77 and its subcellular translocation from the nucleus to the cytosol were induced, resulting in cellular apoptosis and inflammatory lesion. Our further studies revealed that the upregulation of Nur77 was accompanied by the induction of autophagic process. These evidences suggest that Nur77 may be involved in regulating autophagy and have a significant impact on the physiopathological process of PD; however, the specific molecular mechanisms remain unknown. Our preliminary experiments found that Nur77 may modulate AMPK expression level and its kinase activity via the interaction with p53. Based on the fact that AMPK is one of the important modulators of autophagy, we infer that Nur77 may regulate dopaminergic neuronal autophagy and subsequent survival via p53-AMPK signaling pathway. Thus in this project, with the help of molecular biological techniques including gene regulation, we would like to explore the mechanism of Nur77 in modulating autophagy in the PD animal and cell models, in order to answer the scientific problem that whether Nur77 could modulate autophagy via p53-AMPK signaling pathway and how it play an important role underlying the pathogenesis of PD. In conclusion, this study would clarify the mechanism of Nur77 involved in the autophagic dysfunction of dopaminegic neurons from a new perspective, and offer new insights into the development of molecular-targeted therapy in PD.

帕金森病（PD）是严重的神经退行性疾病。我们前期研究发现，6-羟多巴胺（6-OHDA）诱导的PD细胞模型中，孤儿核受体Nur77的表达上调、胞质输出增加，诱导细胞凋亡和炎性损伤；进一步研究发现，Nur77表达上调伴随自噬活动的增强。结合近年研究，我们指出，Nur77可能通过调控自噬参与PD的病理生理过程，但具体作用机制不清。我们预实验发现，Nur77可能通过与p53相互作用，调节腺苷酸活化蛋白激酶（AMPK）的表达和活性，故我们猜想Nur77通过调控p53-AMPK通路，影响多巴胺能（DA）神经元的自噬及存活。本项目拟在PD模型中借助基因调控等分子生物学手段，进行Nur77的自噬调控机制研究，旨在回答Nur77是否通过p53-AMPK通路调控自噬、进而在PD发病机制中发挥关键作用这一科学问题，从新的角度阐明Nur77参与DA神经元自噬功能紊乱的机制，为PD相关分子靶点治疗提供新思路。

帕金森病（PD）是严重的神经退行性疾病。既往研究提示孤儿核受体Nur77可能通过调控自噬参与PD的病理过程，但具体作用机制不清。本项目在PD模型中借助分子生物学手段，进行Nur77的自噬调控机制研究，探讨Nur77是否通过p53-AMPK通路调控自噬进而影响PD病理过程。研究结果发现，6-OHDA诱导的PD疾病模型中，Nur77的表达上调及胞质输出增加；Nur77可诱导自噬增强。生理状态下Nur77以p53为中介抑制AMPK；而病理模型下AMPK mRNA表达和磷酸化活化水平升高，敲减Nur77后AMPK的mRNA表达和磷酸化活化水平反而抑制，提示Nur77在其中发挥的信号转导/调节作用。免疫荧光检测进一步提示炎性损伤PD实验模型下Nur77对自噬活动的促进作用。在另一高糖处理的PD模型中，高糖抑制LC3B表达和自噬活动；高糖应激可能通过诱导SNCA A53T突变转基因小鼠特定脑区磷酸化α-synuclein的生成，促进PD病理过程。遵循基础和临床相结合的思路，我们开展临床研究并发现PD患者血清磷酸化α-synuclein、Nur77及炎症因子水平较对照组发生变化（相关数据正整理中），同时影像学指标视网膜神经纤维层（RNFL）厚度（靠下象限）的变薄与PD认知障碍显著相关，提示相关生物标志物在PD临床诊疗活动中的巨大价值。基于本研究在Nur77/p53/AMPK和相关生物标志物等方面的发现，我们能进一步加深对PD及相关神经退行性疾病的发病机制的认识，推动PD生物标志物的筛选和临床诊疗的进步，为后续新药研发、靶点寻找和临床精准诊疗奠定理论和实验基础。