Abstract: Objective To evaluate PKCε translocation after β-adrenergic stimulation in isolated cardiomyocytes and the cross-talk with Epac and ERK phosphorylation. Methods Rat neonatal cardiomyocytes were cultured and treated with isoproterenol (Iso) and Epac activator 8-CPT. After infected with adenovirus coding for dominant negative (DN) form of Epac (Epac R279K) and adenovirus coding for rabbit muscle cAMP-dependent protein kinase inhibitor (Ad.PKI), cells were subjected to Iso. PKCε content was measured in the particulate fractions of cell lysates by Western blot. The localization of translocation of PKCε was studied by confocal microscope. After using of a specific PKCε inhibitor peptide, cells were treated with Iso, and pERK1/2 expression was assessed by Western blot. Results In cultured rat neonatal cardiomyocytes it was shown that, in response to Iso, PKCε content was increased in particulate fractions of cell lysates, and PKCε was translocated to the perinuclear area determined by confocal microscopy. After incubation with 8-CPT, PKCε content in particulate fractions was increased(P<0.05). Epac R279K blocked Iso-induced PKCε activation. After infected with Ad.PKI, PKCε content was not decreased in particulate fractions by Iso stimulation(P<0.01). Iso-induced ERK phosphorylation was blocked by the specific PKCε inhibitor peptide. Conclusion β-adrenergic stimulation activates PKCε in an Epac-dependent and PKA-independent fashion inducing ERK phosphorylation in cardiomyocytes.

Key words: Key words: β-adrenergic receptor, signal transduction, protein kinase Cε, extracellular signal-regulated kinase