RAGE活化通过TFEB/溶酶体途径抑制神经元自噬的研究

Autophagy dysfunction is a novel pathway in the Alzheimer’s disease. High level of autophagy plays a key homeostatic mechanism to maintain neuronal integrity. Activation of advanced glycation endproducts (RAGE) is an important pathway to neuron injury in AD. We previous study found that activated RAGE inhibited neuronal autophagy through inducing lysosome peripheral location. What is the mechanism of lysosome peripheral location induced by activated RAGE? It is known that transcription factor EB (TFEB) is a crucial regulator of autophagy, and nucleus location of TFEB promoted the activation of lysosome-autophage downstream genes. We further found that activated RAGE inhibited nucleus location of TFEB, and dephosphorylation of TFEB would ameliorate neuronal injury by activated RAGE. Thus we propose that activated RAGE inhibits autophagy of neuron via TFEB/lysosome pathway. In this study, we will clarify the molecular mechanism how activated RAGE inhibits neuronal autophagy by transfection assay, gene silence and ChIP-qPCR assay, and investigate influence of RAGE in neuron injury both in vitro and in transgenetic mice, which will illustrate a new mechanism for neuron protection and advanced intervention for AD.

自噬的改变与阿尔茨海默病（AD）的发生密切相关。高水平自噬是维持神经元内环境稳态的关键因素。糖基化终产物受体（RAGE）活化是诱导神经元损伤从而引发AD的重要途径。我们前期研究发现：RAGE活化通过促进溶酶体外移，抑制神经元自噬。那么，RAGE活化介导溶酶体外移的机制是什么？转录因子EB（TFEB）是重要的自噬调控因子，TFEB入核介导溶酶体-自噬下游基因的活化。我们进一步实验发现：神经元RAGE活化抑制TFEB入核，而恢复TFEB入核可改善RAGE活化引起的自噬抑制。由此提出：RAGE活化是否通过TFEB/溶酶体途径抑制神经元自噬？为解决这一问题，本课题拟采用过表达RAGE的HT22细胞为体外模型，以前脑神经元特异性RAGE转基因小鼠为动物模型，通过质粒转染、基因沉默、ChIP-qPCR等技术，旨在寻找RAGE活化抑制神经元自噬的具体机制，为保护神经元和防治AD提供新的靶点。

阿尔茨海默病（AD）是一种常发于老年人的以进行性认知障碍为主的中枢神经退行性疾病，目前AD的发病机制仍未明确，缺乏有效的防治药物。β淀粉样蛋白（Aβ）是AD发病的最主要因子。同时有研究发现Aβ可通过激活RAGE-CaMKKβ-AMPK信号通路诱导神经母细胞瘤细胞产生自噬小体，提示晚期糖基化终末产物受体（RAGE）介导的自噬与Aβ关联；此外，目前缺乏关注Aβ1-40和RAGE在介导自噬过程中的关系。我们在研究中发现Aβ1-40和RAGE与自噬行为的密切关系，炎症因子CRP则通过C1q调控Aβ42的表达。本研究从这两条主线开展研究并获得了显著性研究结果，有力证明Aβ1-40和RAGE对自噬行为的调控作用和CRP对主要AD因子Aβ42的调控作用，揭示了AD发病的一项新机制。此外本项目还探索了HMGB1-RAGE信号通路与炎性小体 NLRP3 在神经应激过程中的调控关系，为深入了解HMGB1-RAGE信号通路与神经炎症及退行性疾病的发生提供重要启发。