Divergent transcriptional responses to independent genetic causes of cardiac hypertrophy

To define molecular mechanisms of cardiac hypertrophy, genes whose expression was perturbed by any of four different transgenic mouse hypertrophy models [protein kinase C-epsilon activation peptide (Psi epsilon RACK), calsequestrin (CSQ), calcineurin (CN), and G alphaq] were compared by DNA microarray analyses using the similar to8,800 genes present on the Incyte mouse GEM1. The total numbers of regulated genes (tens to hundreds) correlated with phenotypic severity of the model (G alphaq > CN > CSQ > Psi epsilon RACK), but demonstrated that no single gene was consistently upregulated. Of the three models exhibiting pathological hypertrophy, only atrial natriuretic peptide was consistently upregulated, suggesting that transcriptional alterations are highly specific to individual genetic causes of hypertrophy. However, hierarchical-tree and K-means clustering analyses revealed that subsets of the upregulated genes did exhibit coordinate regulatory patterns that were unique or overlapping across the different hypertrophy models. One striking set consisted of apoptotic genes uniquely regulated in the apoptosis-prone G alphaq model. Thus, rather than identifying a single common hypertrophic cardiomyopathy gene program, these data suggest that extensive groups of genes may be useful for the prediction of specific underlying genetic determinants and condition-specific therapeutic approaches.