Sirt1调控FoxO-自噬信号通路在主动脉瓣钙化中的作用及机制研究

Sirt1 is one member of the Sirtuin family, and it could mediate many pathological physiological processes, such as oxidative stress, apoptosis, inflammation, cell phenotype transformation and so on. However, its effect on the aortic valve calcification is still unclear. Our previous study and others’ research results have showed that the valvular interstitial cell(VIC) was the the effector cell of aortic valve calcification, and Sirt1 could alleviate the VIC damage and calcification process by increasing the autophagy level of VICs. Therefore, it was speculated that Sirt1 could alleviate the process of aortic valve calcification by regulating related signaling pathways in VICs. This project aimed to observe the effects of Sirt1 on the FoxO pathway and autophagy level in VICs by targeted intervention of Sirt1 at the cellular level, and to study the effects of Sirt1-FoxO-autophagy pathway in reducing oxidative stress, apoptosis, inflammation, calcification and so on in VICs. Meanwhile, by using mice with Sirt1 gene knockout, the molecular mechanism of Sirt1 in the pathogenesis of aortic valve calcification could be studied in vivo, and this will provide evidence and new targets for prevention and treatment of aortic valve calcification.

Sirt1 是Sirtuin家族的成员之一，在多种疾病中参与介导氧化应激、凋亡、炎症反应、细胞表型转化等病理生理过程，但其在主动脉瓣钙化中的作用尚不明确。相关文献和我们前期研究均显示：瓣膜间质细胞（VIC）是瓣膜钙化效应细胞，Sirt1可通过提高VICs自噬水平从而减轻VIC的损伤及钙化进程。因此Sirt1介导自噬通路可能通过影响调控相关信号通路影响VIC功能，继而减缓主动脉瓣钙化进程。本课题拟通过靶向干预细胞水平Sirt1，观察其对VICs中FoxO通路及自噬的影响，以及Sirt1-FoxO-自噬通路在减轻VIC氧化应激、凋亡、炎症反应、钙化等方面的作用;同时利用Sirt1基因敲除小鼠，在体探讨Sirt1参与主动脉瓣钙化发病的分子机制，为防治主动脉瓣钙化提供理论依据和新的干预靶点。

退行性 CAVD 起病隐匿，发病率日益增高且机制不明。本课题通过探究退行性钙化性主动脉瓣膜病(CAVD)中瓣膜间质细胞(AVICs)自噬流的变化，并进一步探索Ox-LDL通过下调 Sirt1 抑制瓣膜间质细胞自噬流从而促进主动脉瓣钙化的作用机制，通过人体病变组织标本分析、动物模型建立以及体外细胞干预，结果证明钙化瓣膜AVICs自噬流发生异常，ox-LDL是导致CAVD自噬流发生异常的重要原因。其主要机制可能是促进自噬体的形成同时抑制自噬体与溶酶体融合，进而使细胞内堆积大量自噬体，导致AVICs自噬流受到抑制；AVICs中自噬体堆积可促进主动脉瓣膜发生钙化，其重要机制是激活NF-κB通路，从而启动AVICs成骨样分化和炎症反应。CAVD主动脉瓣Sirt1表达下调，ox-LDL是导致Sirt1下调的重要原因；Sirt1通过影响Rab7合成参与调控AVICs自噬流，Sirt1影响AVICs内Rab7合成的可能途径是作用于其底物FoxO1使其去乙酰化；此外，ox-LDL可抑制AVICs的溶酶体功能从而抑制其自噬流。从而为防治退行性 CAVD 提 供新靶点和新思路。