Role of IQGAP1 in mediating angiotensin Ⅱ-induced apoptosis of podocytes and its underlying mechanism / 中华肾脏病杂志

ABSTRACT

Objective To investigate the role of IQ domain GTPase-activating protein 1 (IQGAP1) in angiotensin Ⅱ (Ang Ⅱ)-induced podocyte apoptosis and the underlying mechanism.Methods Differentiated mouse podocytes were exposed to Ang Ⅱ at different concentrations for 6 h or at 10-8 mol/L for variable incubation time.Podocyte apoptosis was assessed by flow cytometry.Expression of IQGAP1 was analyzed by immunofluorescence and Western blotting.IQGAP1 siRNA and MAPK pathway inhibitors(10 μmol/L SB202190,25 μmol/L SP600125,10 μmol/L U0126) were further introduced to investigate the role of IQGAP1 and MAPK signalings in the process.And coimmunoprecipitation was used to evaluate the interaction between ERK1/2 and IQGAP1.Results (1)Ang]] promoted podocyte apoptosis in a dose-and time-dependent manner.(2) IQGAP1 was located in celluar membrane and cytoplasm of cultured podocytes.Exposure to Ang Ⅱ stimulated IQGAP1expression in a dose-and time-dependent manner,and elevated phosphorylation of p38,JNK,and ERK1/2 simultaneously.(3) Pretreatment with SB202190,SP600125,or U0126 dramatically prevented Ang Ⅱ-promoted podocyte apoptosis respectively (P ＜ 0.05).However,the protein level of IQGAP1 was not altered.(4) Knockdown of IQGAP1 with siRNA obviously prevented Ang]Ⅱ-induced apoptosis of podocytes(P ＜ 0.05) and reduced Ang Ⅱ-induced phosphorylation of ERK1/2(P ＜ 0.05),but not that of p38,JNK.This was accompanied by a reduced interaction between ERK1/2 and IQGAP1(P ＜ 0.05).Conclusion IQGAP1 contributes to Ang Ⅱ-induced podocyte apoptosis by interacting with the ERK1/2 signaling protein.