FGF21通过Sirt1-FoxO1通路抑制高糖诱导的自噬延缓血管内皮细胞衰老的机制研究

血管内皮细胞衰老在糖尿病血管并发症中扮演着重要角色，且高糖诱导的内皮细胞过度自噬是造成其衰老的关键环节。前期在小鼠I型糖尿病模型及高糖损伤的内皮细胞中我们已证实FGF21可通过抑制高糖诱导的细胞自噬延缓细胞衰老，并且FGF21是通过促进Sirt1与FoxO1的结合，调节FoxO1的去乙酰化修饰及其与Atg7的解离，实现对自噬的抑制作用，但其中的分子机制有待更为详实的阐明。因此，我们将利用Sirt1基因沉默等手段证实FGF21调控的FoxO1去乙酰化是其抑制高糖诱导的细胞自噬乃至改善细胞衰老的分子基础；随后通过靶向蛋白质组学技术，进一步揭示FGF21调控下FoxO1发生去乙酰化修饰的潜在位点；最后将鉴定出的靶位点替换为谷氨酰胺以模拟不受Sirt1调控的持续乙酰化修饰，通过检测位点突变后FGF21逆转高糖损伤效应的改变，从而详细阐明相关分子机制。本项目有望为糖尿病血管并发症的防治提供新靶点。

Vascular endothelial cell senescence plays a critical role in diabetic vascular complications, and the autophagy induced by high glucose mediates the celluar senescence. In the previous study, we demonstrated both in type I diabetic mice and high glucose stimulated endothelial cells that FGF21 could alleviate celluar senescence through its role in inhibiting autophagy, and the inhibitory effect was achieved by promoting the association between Sirt1 and FoxO1, which could lead to the deacetylation of FoxO1 and its dissociation from Atg7. However, the mechanism remains to be further explored. Thus, we will firstly confirm that FGF21 mediated FoxO1 deacetylation constitutes the main molecular basis for the alleviation of high glucose induced endothelial cell senescence by Sirt1 gene silencing. Secondly, the FoxO1 deacetylation sites modulated by FGF21 will be revealed via targeted proteomics. Finally, the identified deacetylation sites will be replaced with glutamine for mimicking continuous acetylation. Thereby, the underlying mechanism could be elucidated by examining the alteration of FGF21 mediated protective effects against high glucose stimulation after different site mutation. This project is expected to provide new targets for the prevention and treatment of diabetic vascular complications.