Protein Kinase A Determines Timing of Early Differentiation through Epigenetic Regulation with G9a

SummaryTiming of cell differentiation is strictly controlled and is crucial for normal development and stem cell differentiation. However, underlying mechanisms regulating differentiation timing are fully unknown. Here, we show a molecular mechanism determining differentiation timing from mouse embryonic stem cells (ESCs). Activation of protein kinase A (PKA) modulates differentiation timing to accelerate the appearance of mesoderm and other germ layer cells, reciprocally correlated with the earlier disappearance of pluripotent markers after ESC differentiation. PKA activation increases protein expression of G9a, an H3K9 methyltransferase, along with earlier H3K9 dimethylation and DNA methylation in Oct3/4 and Nanog gene promoters. Deletion of G9a completely abolishes PKA-elicited acceleration of differentiation and epigenetic modification. Furthermore, G9a knockout mice show prolonged expressions of Oct3/4 and Nanog at embryonic day 7.5 and delayed development. In this study, we demonstrate molecular machinery that regulates timing of multilineage differentiation by linking signaling with epigenetics.

Graphical AbstractFigure optionsDownload full-size imageDownload high-quality image (195 K)Download as PowerPoint slideHighlights► Timing of early-stage ESC differentiation is accelerated by PKA activation ► PKA increases G9a protein and epigenetic silencing of pluripotent genes ► G9a deletion abolishes PKA effects on differentiation timing and epigenetic silencing ► Inhibition of PKA or G9a delays differentiation and embryonic development in vivo