Apoptosis of RIN-m cells mediated by angiotensin II by mitochondrial pathway

Objective To investigate the effect of angiotensin Ⅱ(AngⅡ) and losartan on β cells,and its related molecular mechanisms.Methods Normally cultured RIN-m cells were divided into three groups:control group(cultured with RPMI 1640 medium),AngⅡ group(treated with 100 nmol/L AngⅡ),losartan group(treated with 1 μmol/L losartan 15min before addition of 100nmol/L AngⅡ).After incubation for another 48h,the apoptosis rate of RIN-m cells was quantified by flow cytometry(FCM) with Annexin-V FITC/PI dual staining.The expressions of Bcl-2 and Bax mRNA and protein were determined by RT-PCR and Western blotting,and the activities of Caspase 3 and Caspase 9 were detected by spectrophotometry.Results The apoptosis rate of RIN-m cells was significantly higher in AngⅡgroup than in both control and losartan group(P0.001),and no significant difference existed between the latter two groups(P0.05).In comparison to the control group,the expressions of Bcl-2 mRNA and protein significantly declined,while of Bax mRNA and protein increased obviously in AngⅡ group(P0.001).No significant difference existed on the expressions of Bcl-2 and Bax mRNA and protein between losartan and control group(P0.05),but the expressions of Bcl-2 mRNA and protein were significantly higher(P0.001),and that of Bax mRNA and protein was obviously lower(P0.001) in losartan group than in AngⅡ group.The activities of Caspase 3 and Caspase 9 were significantly higher in AngⅡ group than in both control and losartan group(P0.05),while no significant difference was found between the latter two groups(P0.05).Conclusion AngⅡ may induce the apoptosis of β cells through mitochondrial pathway,and pre-intervention with losartan,which partly reverses the effect of AngⅡ,may play a protective effect on β cells.