MSK-mediated phosphorylation of Histone 3 Ser28 couples MAPK signaling with early gene induction and cardiac hypertrophy

Abstract Heart failure is a leading cause of death that develops subsequent to deleterious hypertrophic cardiac remodelling. MAPK pathways play a key role in coordinating the induction of gene expression during hypertrophy. Induction of the immediate early gene (IEG) response is a necessary and early event in this process. How MAPK and IEG expression are coupled during cardiac hypertrophy is not yet resolved. Here, in vitro, in rodent models and in human samples, we demonstrate that MAPK-stimulated IEG induction depends on the Mitogen and Stress activated protein Kinase (MSK) and its phosphorylation of histone H3 at serine 28 (pH3S28). pH3S28 in IEG promoters in turn recruits Brg1, a BAF60 ATP-dependent chromatin remodelling complex component, initiating gene expression. Without MSK activity and IEG induction, the hypertrophic response is suppressed. These studies provide new mechanistic insights and highlight the role of signalling to the epigenome in gene expression regulation during cardiac hypertrophy. Brief summary one sentence MSK1/2 phosphorylation of Histone 3 Serine 28 couples MAPK signalling with chromatin remodelling and immediate early gene expression to induce pro-hypertrophic cardiac transcriptional responses.