Differential roles of MAPKs and MSK1 signalling pathways in the regulation of c-Jun during phenylephrine-induced cardiac myocyte hypertrophy.

Gq-protein-coupled receptor (GqPCR) signalling is associated with the induction of cardiac myocyte hypertrophy, which is characterized by an increase in expression of immediate early genes via activation of pre-existing transcription factors. Here, we explore the role of MSK1 and MAPK signalling pathways in the regulation of the immediate early gene c-jun. The results provide further support for the role of MSK1 in cardiac myocyte hypertrophy and indicate that PE activates distinct signalling mechanisms which culminate with a complex activation of c-jun. ERK1/2 and JNKs are the principal kinases responsible for phosphorylation of c-Jun, whereas c-jun mRNA and protein up-regulation by PE is mediated by multiple signalling pathways that include MSK1, ERK1/2, p38-MAPK and JNKs. These signalling mechanisms seem to be critical to the phenotypic changes of cardiac myocytes in response to hypertrophic stimulation.