The fibroblast growth factor signaling axis controls cardiac stem cell differentiation through regulating autophagy.

The fibroblast growth factor (FGF) signaling axis plays important roles in heart development. Yet, the molecular mechanism by which the FGF regulates cardiogenesis is not fully understood. Using genetically engineered mouse and in vitro cultured embryoid body (EB) models, we demonstrate that FGF signaling suppresses premature differentiation of heart progenitor cells, as well as autophagy in outflow tract (OFT) myocardiac cells. The FGF also promotes mesoderm differentiation in embryonic stem cells (ESCs) but inhibits cardiomyocyte differentiation of the mesoderm cells at later stages. Furthermore, inhibition of FGF signaling increases myocardial differentiation and autophagy in both ex vivo cultured embryos and EBs, whereas activation of autophagy promotes myocardial differentiation. Thus, a link between FGF signals preventing premature differentiation of heart progenitor cells and suppression of autophagy has been established. These findings provide the first evidence that autophagy plays a role in heart progenitor differentiation, and suggest a new venue to regulate stem/progenitor cell differentiation.