Current Genomics, 2010, 11, 287-296 287 Transcription Factor CHF1/Hey2 Regulates Specific Pathways in Serum Stimulated Primary Cardiac Myocytes: Implications for Cardiac Hypertrophy Man Yu 1 , Fan Xiang 1 , Richard P. Beyer2, Federico M. Farin2, Theo K. Bammler2 and Michael T. Chin*,1 1Division of Cardiology, Department of Medicine, University of Washington, Seattle, WA, USA 2Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA Abstract: We have previously found that overexpression of CHF1/Hey2 in the myocardium prevents the development of phenylephrine-induced hypertrophy. To identify transcriptional pathways regulated by CHF1/Hey2, we cultured primary neonatal mouse cardiac myocytes from wild type and transgenic mice overexpressing CHF1/Hey2 and treated them with serum, a potent hypertrophic stimulus. We verified that overexpression of CHF1/Hey2 suppressed cardiac myocyte hyper- trophy induced by serum and then determined transcriptional profiles by microarray hybridization. We identified and veri- fied important downstream target genes by single gene analysis and qRT-PCR and then identified important biological processes by Gene Set Analysis using Biological Process Gene Sets from the Gene Ontology Consortium. We found that CHF1/Hey2 suppresses pathways involved in water transport, adenylate cyclase activity, embryonic eye morphogenesis, gut development and fluid transport after serum stimulation. Genes involved in protein dephosphorylation, demonstrate increased expression in myocytes overexpressing CHF1/Hey2, independent of serum treatment. Genes overexpressed prior to serum treatment are involved in regulation of transcription factor activity, nuclear protein export and steroid hor- mone receptor signaling. Genes overexpressed after serum treatment are involved in autophagy, apoptosis and mitochon- drial biogenesis. Received on: January 10, 2010 - Revised on: February 22, 2010 - Accepted on: March 03, 2010 Keywords: Cardiac hypertrophy, microarray, transcription factor. INTRODUCTION Cardiac hypertrophy is an important biological process in which individual cardiac myocytes enlarge in response to exogenous stimuli. Enlargement of myocytes is associated with an increased number of sarcomeres, myofibrils and in- creasing myocyte width, resulting in an increased ventricular wall thickness. Although hypertrophy is initially compensa- tory, prolonged exposure to hypertrophic stimuli can ulti- mately lead to contractile dysfunction and apoptotic cell death, resulting in cardiac failure and fibrosis. Heart failure is a leading cause of morbidity and mortality in Western So- ciety, with the incidence increasing every year. Understand- ing the molecular basis for the development of hypertrophy, its progression to heart failure and the biological pathways involved in this syndrome will have important preventative, diagnostic and therapeutic implications. We have previously reported that the Hairy-related bHLH transcriptional repressor, CHF1 (also called Hey2, Hesr-2, Hrt2, HERP1 and gridlock), functions as a suppres- sor of cardiac hypertrophy induced by phenylephrine [1]. Suppression of cardiac hypertrophy is mediated, at least in part, by the binding of CHF1/Hey2 to the transcription factor *Address correspondence to this author at the Center for Cardiovascular Biology, University of Washington School of Medicine, Box 358050, 815 Mercer Street, Rm 353, Seattle, WA 98109, USA; Tel: 206 616-8880; Fax: 206 616-4082; E-mail: mtchin@u.washington.edu GATA4, thereby inhibiting the ability of G ATA4 to activate atrial natriuretic factor (ANF) gene expression along with other genes associated with cardiac hypertrophy [1-3]. CHF1/Hey2 is normally expressed in the developing heart and vasculature and plays a critical role in heart develop- ment, possibly as an effector of Notch signaling, as previ- ously described [4-12]. Additional studies have underscored the importance of CHF1/Hey2 in the development of the myocardium, as loss of CHF1/Hey2 leads to a thin walled myocardium [13], cardiomyopathy [10] and ectopic expres- sion of atrial genes in the ventricular myocardium [14, 15]. In order to identify pathways relevant to cardiac hyper- trophy in the cardiac myocyte transcriptome that are regu- lated by CHF1/Hey2, we examined the expression of genes in isolated wild type and transgenic myocytes treated with serum, a potent hypertrophic stimulus. Here we report that CHF1/Hey2 suppresses the adenylate cyclase pathway, genes involved in water transport and activates cellular phosphatases and genes involved in autophagy. These find- ings suggest important new pathways in regulation of hyper- trophy. MATERIALS AND METHODS Transgenic Mice, Neonatal Mouse Myocyte Culture and In Vitro Hypertrophy Assays Transgenic mice overexpressing CHF1/Hey2 in the myo- cardium under the control of the mlc2v promoter and neona- 1389-2029/10 $55.00+.00 ©2010 Bentham Science Publishers Ltd.