Protein kinase C epsilon‐dependent extracellular signal‐regulated kinase 5 phosphorylation and nuclear translocation involved in cardiomyocyte hypertrophy with angiotensin II stimulation

Abstract

Angiotensin II (Ang II) plays a critical role in hypertrophy of cardiomyocytes; however, the molecular mechanism, especially the signaling cascades, in cardiomyocytes remains unclear. In the present study, we examined the mechanism of Ang II in hypertrophy of cardiomyocytes. Ang II rapidly stimulated phosphorylation of protein kinase C epsilon (PKCε) in a time- and dose-dependent manner via Ang II receptor-1 (AT₁). Furthermore, Ang II-induced extracellular signal-regulated kinase 5 (ERK5) phosphorylation and translocation was mediated through a signal pathway that involves AT₁ and PKCε, which resulted in transcriptional activation of myocyte enhancer factor-2C (MEF2C) and hypertrophy. Consequently, inhibiting PKCε or ERK5 by small interfering RNA (siRNA) significantly attenuated Ang II-induced MEF2C activation and hypertrophy of rat cardiomyocytes. These data provide evidence that PKCε-dependent ERK5 phosphorylation and nucleocytoplasmic traffic mediates Ang II-induced MEF2C activation and cardiomyocyte hypertrophy. PKCε and ERK5 may be potential targets in the treatment of pathological vascular hypertrophy associated with the enhanced renin–angiotensin system. J. Cell. Biochem. 109: 653–662, 2010.