老年人动脉粥样斑块钙化发病显著升高。衰老下调Sirt1，前期发现Sirt1过表达抑制oxLDL诱导的高代人主动脉平滑肌细胞向成骨细胞分化，Sirt1沉默促进oxLDL诱导的细胞向成骨细胞分化，提示Sirt1介导衰老所致动脉粥样斑块钙化。资料及前期结果提示内质网应激下游EIF2α-ATF4促进人主动脉平滑肌细胞向成骨细胞分化。我们发现Sirt1与EIF2α蛋白结合，同时Sirt1沉默促进oxLDL诱导的EIF2α磷酸化及下游ATF4表达，而不影响内质网应激其他通路。鉴于Sirt1的去乙酰化作用，我们推测Sirt1可能通过抑制EIF2α乙酰化，从而抑制EIF2α磷酸化及ATF4表达，抑制动脉粥样斑块钙化。本项目将利用血管平滑肌特异性Sirt1、ATF4敲除及Sirt1过表达小鼠，并在细胞中利用免疫沉淀、蛋白质谱等手段，研究Sirt1通过EIF2α-ATF4调控衰老介导的动脉粥样斑块钙化的机制。

The incidence of atherosclerotic calcification significantly increased in older adults, which indicates aging to be a potential inducer of atherosclerotic calcification. The expression and activity of Sirt1 reduced during aging. Our preliminary studies found that Sirt1 overexpression inhibits oxLDL-induced osteoblastic differentiation of human aortic smooth muscle cells, while Sirt1 silencing promotes oxLDL-triggered osteoblastic differentiation of the cells. These data suggest that Sirt1 is possible to be involved in aging-induced atherosclerotic calcification. Reports and our data showed EIF2α-ATF4, downstream of endoplasmic reticulum stress pathway, involved in osteoblastic differentiation of human aortic smooth muscle cells. We further found Sirt1 binds with EIF2α. Moreover, Silencing of Sirt1 promotes oxLDL-induced EIF2α phosphorylation and downstream ATF4 expression, but has no effect on other endoplasmic reticulum stress pathways. Based on the deacetylation function of Sirt1, we further hypothesized that Sirt1 may promote EIF2α deacetylation, which further inhibits EIF2α phosphorylation and ATF4 expression, and therefore prevents atherosclerotic calcification. This project will utilize both vascular smooth muscle cell-specific Sirt1 and ATF4 knockout, as well as Sirt1 transgenic mice, and human aortic smooth muscle cells to study the mechanisms of Sirt1 regulating aging-mediated atherosclerotic calcification via EIF2α-ATF4 pathway.