Arf介导GSDMD转运及焦亡孔道的形成在阿尔茨海默病病理进程中的机制研究

Arf is a family of small GTPases, while its activity is dependent on the GTP-GDP cycle, and Arf6 is thought to regulate the membrane traffic, secretion, cell migration and so on. In the hippocampus and cortex of the APP/PS1 mice, which is a model of the AD (Alzheimer’s Disease, AD), there are increased Arf6 expressions and inhibited neurogenesis, and the levels of AP-1 and AP-2 are also changed. Meanwhile, the levels of the NLRP3 and Caspase-1 are up-regulated. The bioinformatics analysis shows that Arf1, GSDMD, NLRP3 and their interacting proteins involve the trans-Golgi network AP-1 binding coupled with cargo capture, positive regulation of cytokine secretion and so on. To summarize the preliminary experimental results and the literatures, we raise the hypothesis that the reduced level of the Arf in the brain of AD, which takes part in the connection of the GSDMD and Adaptor proteins, enhances the transport of GSDMD to the membranes and the formation of pyroptosis pores, then induces the pyroptosis. Therefore, in the project, we will breed the APP/PS1 mice to analysis whether Arf overexpression/knock-down could regulate the GSDMD location, pores formation, and pyroptosis. This study will be helpful to understand the involvement of Arf in the pathophysiology of Alzheimer disease.

ADP核糖基化因子（ADP ribosylation factor, Arf）是一种小分子GTP结合蛋白，活性依赖于与GTP/GDP结合的循环，Arf6主要参与调控细胞膜的转运、分泌、迁移等。在APP/PS1小鼠脑中海马和皮层的Arf6表达上调、衔接蛋白复合物1（Adaptor protein complex, AP-1）和AP-2的表达均出现了变化，而神经元生成和迁移明显减弱，与此同时，NLRP3和Caspase-1的表达出现了上调。生物信息学分析表明Arf1、GSDMD、NLRP3及其相互作用蛋白涉及的生物过程主要为dTGN上的AP-1结合捕获目标蛋白、细胞因子的分泌等。综合前期实验结果与文献，我们推测Arf6在AD脑内高表达，并通过调节GSDMD与AP-2、AP-1的结合，促进GSDMD转运至细胞膜形成焦亡孔道，诱发细胞焦亡，为揭示Arf参与AD的发病机制提供充分的理论依据。

阿尔茨海默病（Alzheimer’s Disease, AD）的发生和发展过程中，神经炎症出现明显增加，炎症小体的异常活化诱发的细胞焦亡可能成为病理因素之一。鉴于此，本项目拟采用NOD样受体热蛋白结构域相关蛋白3（NOD-like receptor thermal protein domain associated protein 3, NLRP3）特异性抑制剂MCC950，结合生物信息学分析、分子生物学和行为学等手段，探索炎症小体加剧AD小鼠学习记忆能力损伤的病理学机制。AD的主要病理特征之一是脑内出现β-淀粉样蛋白（amyloid-β protein, Aβ）沉积，而Aβ是淀粉样前体蛋白（amyloid precursor protein, APP）经由β分泌酶（beta-site APP-cleaving enzyme, BACE1）剪切得到的短肽。 本项目以Aβ沉积这一AD主要病理特征为切入点，探索了MCC950调控APPh和BACE1的异常剪切在淀粉样斑块形成过程中的分子机制，最终揭示MCC950可能通过促进蛋白质量控制（protein quality control, PQC）调控APP和BACE1的降解，从而参与蛋白质量控制调控AD发生发展过程的分子机制，为防治AD奠定理论和实践基础。