Autophagy-Sirtuin1(SIRT1) Modulated The Endothelial Progenitor Cells (EPCs) Proliferation and Migration Via wnt/β-Catenin/GSK3β Signaling Pathway and Alleviated The Coronary Atherosclerosis (CAS) in Mice

Background and purpose: SIRT1 exerted its link to CAS risk in humans and EPCs presented its reparative role in CAS. In this study, we explored the role of SIRT1 in CAS mice and also its modulation in EPCs.Methods and materials: ApoE-/- mice were fed with high-fat and high-glucose food to establish the CAS animal model with the normally-raised C57BL/6 mice as a healthy control group. 5 ApoE mice were intravenously injected with SIRT1 activator, SRT 2104 and another 5 were injected with inhibitor Nicotinamide in tail. Weight changes were recorded per week. Blood samples were taken from posterior orbital venous plexus and detected by automatic biochemical analyzer for lipid concentrations. Coronary artery tissues were observed. HE staining displayed the pathological condition while Immunohistochemistry (IHC) evaluated the CD34+/VEGFR2+ relative density. In vitro, EPCs were isolated from bone marrow each group and then purified, cultured and verified using immunofluorescence staining (IFS). Thereafter, we examined the modulatory mechanism of SIRT1 in EPCs by RT-PCR, MTT, Western Blot (WB) and colony formation, scratch methods, connecting the wnt/β-catenin/GSK3β signaling pathway.Results：SIRT1 activation negatively regulated the weight and TC, TG and LDL. SIRT1 activator alleviated the lesion area and decreased the CD34+/VEGFR2+ density which was higher in coronary artery tissues in CAS and SIRT1 inhibitor groups. In vitro, SIRT1 activator promoted the bone marrow-derived EPCs proliferation, migration and activated wnt/β-catenin/GSK3β signaling pathway while inhibited the autophagy biomarkers ATG1 and LC3II. Furthermore, inhibition of autophagy led to the upregulation of SIRT1 and increase in cell proliferation, migration and wnt/β-catenin/GSK3β activity. The suppression of the pathway in turn lowered SIRT1 expression in EPCs, attenuated the cell proliferation and migration and promoted autophagy. Conclusion: Taken all the findings together, this research disclosed that SIRT1 activator might perform its protective role in CAS through autophagy inhibition via wnt/β-catenin/GSK3β signaling pathway in EPCs.