mTOR-STAT3-Notch信号通路介导的自噬在ALDH2改善阿尔茨海默病认知障碍中的作用

More and more evidence shows that aldehyde dehydrogenase-2 (ALDH2) is the key mediator of endogenous cytoprotection. It's reported that ALDH2 gene deficiency results in an elevated incidence of Alzheimer's Disease (AD), and ALDH2-knockout mice are more susceptible to oxidative stress injury, age-related neurodegenerative diseases and amnesia. Recently Nature reported that the autophagy plays a crucial role in the occurrence and development of AD. Our previous study showed overexpression of ALDH2 can improve the cognitive impairment in AD mice, accompanied by AD mice significantly upregulated autophagy related protein, and down-regulation of upstream signal molecule mTOR-STAT3-Notch of autophagy, suggesting that ALDH2 may play a role in improving cognitive impairment of AD by activating mTOR-STAT3-Notch mediated autophagy. However, what is the key signalling contribute to ALDH2-induced neuroprotection against recognitive dysfunction and autophagy under AD? Autophagy under AD is a "friend" or "enemy"? They are not clear. In this project, the ALDH2 overexpressed AD mouse will be used which is our lab's initiative. To give a deep insight into the autophagy mechanism of neuroprotective effect of ALDH2 on improving cognitive dysfunction in AD, the methods such as behavior study, histology, cell biology and physiology will be used. The study will provide direct evidence for ALDH2 used in the AD treatment, and broaden the new concepts in discovering drugs in AD treatment.

ALDH2是介导细胞内源性保护的关键物质。据报道，ALDH2基因缺失增加患AD风险；ALDH2敲除小鼠更易遭受氧化应激损伤、导致AD。新近Nature报道自噬在AD发生发展中起着至关重要的作用。我们前期研究结果显示ALDH2过表达确能改善AD鼠认知障碍，并伴有AD鼠自噬蛋白LC3BII显著上调、自噬上游信号分子mTOR-STAT3-Notch下调，提示ALDH2改善AD认知障碍可能通过激活mTOR-STAT3-Notch介导的自噬起作用。然而ALDH2发挥AD神经保护的自噬机制及其关键信号分子是什么？AD中自噬"是敌是友"？国内外未见明确报道。本研究拟应用国际首创的ALDH2过表达AD小鼠模型，从行为学、组织学、细胞生物学、生理学等多方位、全面深入探讨ALDH2改善AD认知障碍中mTOR-STAT3-Notch介导自噬及其作用地位。为ALDH2应用于AD治疗提供证据，为AD药物研发开辟思路

ALDH2发挥关键性细胞保护作用；ALDH2基因缺失增加患AD风险；神经退行性疾病均伴随自噬的紊乱。前期研究已证实ALDH2确能改善AD小鼠认知，且自噬发挥重要作用。在前期细胞水平研究的基础上，本课题从动物水平探索mTOR-STAT3-Notch1信号通路在ALDH2改善AD认知障碍的作用机制。首先完成了ALDH2、 APP/PS1及其三转转基因小鼠的传代和鉴定工作。进一步的试验结果显示ALDH2过表达APP/PS1转基因AD小鼠的行为学较APP/PS1痴呆小鼠明显改善，旷场试验结果显示，ALDH2过表达APP/PS1小鼠活动总距离、和核心区活动时间和距离均较APP/PS1组延长，差异有统计学意义；Western blot显示，蛋白水平mTOR在APP/PS1小鼠组表达明显降低，ALDH2过表达APP/PS1小鼠明显升高。为进一步探索mTOR自噬下游分子，课题组采用AAV-ALDH2腺病毒脑定位注射的方法观察ALDH2过表达对AD小鼠行为学、组织学和分子生物学指标的影响。结果发现ALDH2过表达改善了AD小鼠的探索行为，AD小鼠海马自噬蛋白表达明显降低、HDAC1升高，而这一现象可被ALDH2过表达抵消，提示HDAC1可能是mTOR下游的关键分子。