The Role And Mechanism Of AngⅡ Induced Autophagy Via A STAT3-dependent Pathway In VSMCs Proliferation

Background and purpose Abnormal vascular smooth muscle cells（VSMCs）proliferation is the basic pathophysiology of hypertension,atherosclerosis and other vascular diseases,thoroughly understand the induced factors and mechanism of abnormal VSMCs proliferation for preventing and treatmenting of the diseases has important theoretical significance and scientific value.Autophagy is a protective mechanism of eukaryotes for cells maintaining cellular homeostasis in the stress state.Recent studies have shown that autophagy involved in a variety of cytokines,vascular active substances,shear stress and ncRNA induced VSMCs proliferation.some signaling pathways regulate mammalian cell autophagy（such as PI3K/AKT/mTOR）is also important signaling pathways regulating cell proliferation.AngiotensinⅡinduces abnormal VSMCs proliferation through oxidative stress and JAK2-STAT3,p38MAPK,PI3K/Akt signal transduction pathways.A new study has found that AngⅡinduced VSMCs autophagy via oxidative stress and RhoA/Rho Kinase（ROCK）signaling pathways.MiR-17-5p induced autophagy by negatively regulating STAT3 to against VSMCs apoptosis.This research applicates molecular biology methods to explore the role of STAT3 signaling pathway of autophagy in AngⅡinduced abnormal VSMCs proliferation and provide experimental data for revealing the pathophysiological mechanism of vascular remodeling diseases.Method（1）Treatmeat Human aortic vascular smooth muscle cells with different concentrations of AngⅡfor different processing time,applying Western detects Beclin,LC3B-Ⅱ,P62 protein expression;Setting up control group,chloroquine group,AngⅡgroup,chloroquin+AngⅡgroup,using western blot detects LC3B-Ⅱprotein expression.（2）Human aortic vascular smooth muscle cells treated by AngⅡwith different concentrations or different processing time and Setting up control group,chloroquine group,AngⅡgroup,chloroquin+AngⅡgroup,using western blot detects PCNA protein expression.（3）Human aortic vascular smooth muscle cells treated by AngⅡwith different concentrations for 24 hours,western blot detects STAT3,ph-STAT3^Tyr705protein expression;Setting up control group,AngⅡgroup,AngⅡ+DMSO group,AngⅡ+cryptotanshinone（STAT3 Tyr705phosphorylation inhibitors）group,Western blot detects Beclin,LC3B-Ⅱ,Atg7 protein expression.Results（1）Beclin,LC3B-Ⅱ,P62 protein expression level tend to increase with increasing AngⅡconcentration（P<0.05）and treatment time（P<0.05）;chloroquine+AngⅡgroup’s LC3B-Ⅱprotein increased compared to AngⅡtreatment group（P<0.05）.（2）PCNA protein expression level tend to increase with increasing AngⅡconcentration（P<0.05）and treatment time（P<0.05）;chloroquine+AngⅡgroup’s PCNA protein decreased compared to AngⅡtreatment group（P<0.05）.（3）The proportion of STAT3 Tyr705 phosphorylation is AngⅡdose dependent;cryptotanshinone+AngⅡgroup’s ph-STAT3 ^Tyr705,Beclin,LC3B-Ⅱ,Atg7 protein decreased compared to AngⅡtreated group（P<0.05）.Conclusion:1.AngⅡmay be induce autophagy of VSMCs.2.Autophagy may be inhibite VSMCs proliferation.3.STAT3 signaling pathway may be involve in the AngⅡinduced VSMCs autophagy.