Signaling Pathway for Endothelin-1-and Phenylephrine-Induced cAMP Response Element Binding Protein Activation in Rat Ventricular Myocytes: Role of Inositol 1,4,5-Trisphosphate Receptors and CaMKII

Background/Aims: Endothelin-1 (ET-1) and the a1-adrenoceptor agonist phenylephrine (PE) activate cAMP response element binding protein (CREB), a transcription factor implicated in cardiac hypertrophy. The signaling pathway involved in CREB activation by these hypertrophic stimuli is poorly understood. We examined signaling pathways for ET-1- or PE-induced cardiac CREB activation. Methods: Western blotting was performed with pharmacological and genetic interventions in rat ventricular myocytes. Results: ET-1 and PE increased CREB phosphorylation, which was inhibited by blockade of phospholipase C, the extracellular-signal-regulated kinase 1/2 (ERK1/2) pathway, protein kinase C (PKC) or Ca2+-calmodulin-dependent protein kinase II (CaMKII). Intracellular Ca2+ buffering decreased ET-1- and PE-induced CREB phosphorylation by >= 80%. Sarcoplasmic reticulum Ca2+ pump inhibitor, inositol 1,4,5-trisphosphate receptor (IP R-3) blockers, or type 2 IP R-3 (IP (3)R2) knock-out abolished ET-1- or PE-induced CREB phosphorylation. ET-1 and PE increased phosphorylation of CaMKII and ERK1/2, which was eliminated by IP R-3 blockade/knock-out or PKC inhibition. Activation of CaMKII, but not ERK1/2, by these agonists was sensitive to Ca2+ buffering or to Go6976, the inhibitor of Ca2+- dependent PKC and protein kinase D (PKD). Conclusion: CREB phosphorylation by ET-1 and PE may be mainly mediated by IP (3)R2/Ca2+-PKC-PKD-CaMKII signaling with a minor contribution by ERK1/2, linked to IP (3)R2 and Ca2+- independent PKC, in ventricular myocytes. (C) 2017 The Author(s) Published by S. Karger AG, Basel