Interplay of Phosphorylated Apoptosis Repressor with CARD, Casein Kinase-۲ and Reactive Oxygen Species in Regulating Endothelin-۱–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-۱ 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-۲ 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 (T۱۴۹ 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-۱–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-۲ in Endothelin–induced hypertrophy, mainly through its phosphorylation of ARC.