| Objective To investigate the role of poly (ADP-ribose) polymerase1 in regulation of the enymatic activities of Hsp70 through PI3K/Akt pathway in cultured rat cardiac myocytes.Methods Primary cultured neonatal cardiomyocytes were divided into 5 groups, at random. Group 1 (control group) received no treatment. Group 2 (AngⅡgroup) received treatment with AngⅡ(10-7mol/l) alone for 24 hours. Group 3(3AB group) were pretreated with 20mmol/l PARP inhibitor 3-aminobenzamide(3AB) for 1 hour, followed by incubation with AngⅡ(10-7mol/l) for 24 hours. Group 4(LV group) were pretreated with 25mmol/l PI3K inhibitor LY294002(LY)for 1 hour, followed by incubation with AngⅡ(10-7mol/l) for 24 hours. Group 5 (VAL group) were pretreated with 10-7mol/l Valsartan(VAL)for 1 hour, followed by incubation with AngⅡ(10-7mol/l) for 24 hours. PARP activity of cultured cells was measured with TCA precipitation method. Expression of PARP-1, Akt1,Hsp70 was measured with Western Blot. The interaction between PARP-1 and Akt1 was measured with Co-Immunoprecipitation.Results In cardiomyocytes AngⅡcan increase the expression of PARP-1,Akt1,Hsp70。Inhibition of PARP-1 by 3AB effectively boosted AngⅡ-induced increases in the expression of Akt1 and Hsp70. Akt1 can physically be connected with PARP-1 and it can also be poly(ADP-ribosel)ated by PARP-1 activities, while PARP-1 can also be phosphorylated. Conclusions This study illustrated that activation and overexpression of PARP-1 could decrease the expression and activity of Akt1, which can further affect the expression of Hsp70. PARP-1 modulates PI3K/Akt1 pathway both by protein-protein interaction and by poly(ADP-ribosel)ation, meanwhile ,PARP-1 may also be modulated by ways of phosphorylation.
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