Interplay of Phosphorylated Apoptosis Repressor with CARD, Casein Kinase-2 and Reactive Oxygen Species in Regulating Endothelin-1–Induced Cardiomyocyte Hypertrophy

OBJECTIVE(S) The role of the Apoptosis repressor with caspase recruitment domain (ARC) in apoptosis and in certain hypertrophic responses has been previously investigated, but its regulation of Endothelin-1 induced cardiac hypertrophy remains unknown. The present study discusses the inhibitory role of ARC against endothelin-induced hypertrophy. RESULTS In present study Endothelin treated cardiomyocytes were used as a hypertrophic model, that were subsequently treated with adenovirus ARC and its mutant at different multiplicity of infections. Casein-kinase-2 inhibitors were used to produce dephosphorylated ARC and to study its effect on hypertrophy. Hypertrophy was assessed by cell surface area measurement, Atrial-natriuretic-Factor mRNA analysis and total protein assay. Reactive oxygen species analysis was carried out using the dichlorofluorescin-diacetate (DCFH-DA) assay. Over expression of ARC significantly inhibits Endothelin-induced cardiomyocyte hypertrophy. The nonphosphorylated mutant ARC (T149 A) remained unable to control endothelin-induced hypertrophy, suggesting a vital role for ARC phosphorylation in regulation of its activity. Sensitization study has been carried out to check the role of endogenous ARC using casein-kinase inhibitors. Finally, the significant role of ARC in regulating reactive oxygen species -mediated control of endothelin induced hypertrophy has also been assessed. Conclusion : Conclusively, present study showed the vital and potential therapeutic interventional role of ARC in preventing endothelin-1-induced cardiomyocyte hypertrophy. The regulation of hypertrophic pathway by ARC relies on blunting the reactive oxygen species attack. This study further suggests a mediatory role of casein-kinase-2 in Endothelin-induced hypertrophy, mainly through its phosphorylation of ARC.