CHF1/Hey2 Regulates Hypertrophy Analysis of individual components of gene sets that are activated in the CHF1/Hey2 transgenic myocytes only in the absence of serum reveals a number of interesting proteins that regulate the function and/or transport of other proteins. Genes involved in regulation of transcription factor activity (GO: 0051090) include UBE2N, SUMO1, ABRA, COMMD7, PRDX3, JMY and MALT1. These molecules can regulate the activity of important transcriptional activa- tors or coactivators, such as p53 (SUMO1), HIF1 (SUMO1), SRF (ABRA), p300 (JMY) and NF-kB (UBE2N, COMMD7, PRDX3, MALT1). Genes involved in protein export from the nucleus (GO: 0006611) include XPO7, CALR, GSK3B, PRKACA, PTPN11 and DUSP16. XPO7 is involved in general export of nuclear proteins, CALR is in- volved in nuclear export of steroid hormone receptors, while GSK3B, PRKACA, PTPN11 and DUSP16 are also involved in signal transduction as kinases (GSK3B, PRKACA) or phosphatases (PTPN11, DUSP16). Genes involved in steroid hormone receptor signaling (GO: 0030518) include MED1, JMJD1A, PIAS1, NR3C2, JAK2, MED30, PGR, MED14 and PPARGC1A. Genes involved in regulation of phos- phoprotein phosphatase activity include PPP2R4, SAPS2, JAK2, SAPS1, SAPS3, RCAN1 and PPP1R2. Increased ex- pression of these various genes only in the absence of serum suggests differences in baseline metabolism of the transgenic myocytes, however, their role in cardiac myocyte hypertro- phy is unclear, as the differences in expression do not persist after serum stimulation. Analysis of individual components of gene sets that are activated in the CHF1/Hey2 transgenic myocytes after serum stimulation reveals a surprising number of genes that play roles in autophagy and apoptosis. Genes involved in auto- phagy (GO: 0016236, GO: 0000045) include ATG4A, ATG9A, MAPILC3A, ATG4C, ATG16L1, FRAP1, ATG5, and ATG4D (Fig. (7)). Genes involved in apoptosis and cel- lular component disassembly (GO: 0006309, GO: 0006921, GO: 0030262, GO: 0022411) include CECR2, CIDEA, CYCS, DFFA, BNIP3 and AIFM1 (Fig. (8)). Genes involved in mitochondrial biogenesis (GO: 0007005) include NDUFS5, DAP3, VDAC1, DNAJC19, MTX2, MIPEP, DCTN6, AIFM2, AIP, FXN, DNAJ3, BNIP3, IMMP2L, AIFM1, TIMM8B, TIMM10, TIMM9 and NDUFS8 (Fig. (9)). Genes involved in viral reproduction (GO: 0022415) include HBXIP, TNIP1, HIPK2, INSR, FURIN, XRCC4, XRCC6, CCL5, USF1, WWP1, ITCH, WWP2, NFIA, LIG4 and SMAD3. Activation of autophagy genes is interesting, and is consistent with a protective role for autophagy in the heart [26, 27], as previously suggested. Activation of apop- totic genes is paradoxical, as the transgenic hearts are known to be resistant to hypertrophy and apoptosis [28], and may reflect a homeostatic feedback loop in response to a down- stream block to apoptosis. DISCUSSION We have previously found that CHF1/Hey2 overexpres- sion in the myocardium blunts the hypertrophic response induced by phenylephrine both in vivo and in vitro [1]. To further delineate transcriptional pathways regulated by CHF1/Hey2 specifically in cardiac myocytes that are rele- vant to hypertrophy, we cultured cardiac myocytes from wild type and transgenic mice and treated them with serum. As Current Genomics, 2010, Vol. 11, No. 4 293 Fig. (7). Heat map for genes associated with macroautophagy (GO: 0016236). Columns represent microarray data obtained from inde- pendent primary cultures of cells of the indicated genotype and therefore represent biological replicates. Gene name abbreviations for each component of the gene set are indicated at the end of each row. Green indicates expression is lower, while red indicates ex- pression is higher than average of WT. The genes in this set are predominantly upregulated in the transgenic cells (TgS1/2/3/4/5/6/ 7) in the presence of serum relative to the WT cells treated with serum (WTS 1/2/3/4/5/6/7). expected, transgenic overexpression of CHF1/Hey2 pre- vented the development of hypertrophy induced by serum. We next compared their transcriptomes before and after se- rum treatment. As described above, we have found that CHF1/Hey2 regulates a number of gene sets that may play important roles in cardiac hypertrophy. The identification of specific biological processes altered by CHF1/Hey2 through Gene Set Analysis reveals both pre- viously identified and novel pathways that likely affect the development of hypertrophy. Numerous microarray studies examining the transcriptional profiles in various models of hypertrophy have been performed, but consensus findings