ABSTRACT: Myocardin is a remarkably potent transcriptional coactivator expressed specifically in cardiac muscle lineages and smooth muscle cells during postnatal development. Myocardin shares homology with myocardin-related transcription factor-A (MRTF-A), which are expressed in a broad range of embryonic and adult tissues. Our previous results show that myocardin induces cardiac hypertrophy. However, the effects of MRTF-A in cardiac hypertrophy remain poorly understood. Our present work further demonstrates that myocardin plays an important role in inducing hypertrophy. At the same time, we find that overexpression of MRTF-A in neonatal rat cardiomyocytes might induce cardiomyocyte hypertrophy. Furthermore, MRTF-A expression is induced in phenylephrine, angiotensin-II, and transforming growth factor-β-stimulated cardiac hypertrophy, whereas a dominant-negative form of MRTF-A or MRTF-A siRNA strongly inhibited upregulation of hypertrophy genes in response to hypertrophic agonists in neonatal rat cardiomyocytes. Our studies indicate that besides myocardin, MRTF-A might play an important role in cardiac hypertrophy. Our findings provide novel evidence for the future studies to explore the roles of MRTFs in cardiac hypertrophy.
International Union of Biochemistry and Molecular Biology Life 01/2011; 63(1):54-61. · 3.51 Impact Factor