Serum response factor micromanaging cardiogenesis.

Serum response factor (SRF), a cardiac-enriched transcription factor, is required for the appearance of beating sarcomeres in the heart. SRF may also direct the expression of microRNAs (miRs) that inhibit the expression of cardiac regulatory factors. The recent knockout of miR-1-2, an SRF gene target, showed defective heart development, caused in part by the induction of GATA6, Irx4/5, and Hand2, that may alter cardiac morphogenesis, channel activity, and cell cycling. SRF and cofactors play an obligatory role in cardiogenesis, as major determinants of myocyte differentiation not only by regulating the biogenesis of muscle contractile proteins but also by driving the expression of silencer miRNA.