Microarray analysis of gene expression during early stages of mild and severe cardiac hypertrophy.

Familial hypertrophic cardiomyopathy (FHC) is a disease characterized by ventricular hypertrophy, fibrosis, and aberrant systolic and/or diastolic function. We previously developed two transgenic mouse models that carry FHC-associated mutations in alpha-tropomyosin (TM): FHC alpha-TM175 mice show patchy areas of mild ventricular disorganization and limited hypertrophy, whereas FHC alpha-TM180 mice exhibit severe hypertrophy and fibrosis and die within 6 mo. To obtain a better understanding of the molecular mechanisms associated with the early onset of cardiac hypertrophy, we conducted a detailed comparative analysis of gene expression in 2.5-mo-old control, FHC alpha-TM175, and alpha-TM180 ventricular tissue. Results show that 754 genes (from a total of 22,600) were differentially expressed between the nontransgenic (NTG) and the FHC hearts. There are 178 differentially regulated genes between NTG and the FHC alpha-TM175 hearts, 388 genes are differentially expressed between NTG and FHC alpha-TM180 hearts, and 266 genes are differentially expressed between FHC alpha-TM175 and FHC alpha-TM180 hearts. Genes that exhibit the largest increase in expression belong to the "secreted/extracellular matrix" category, and those with the most significant decrease in expression are associated with "metabolic enzymes." Confirmation of the microarray analysis was conducted by quantitative real-time PCR on gene transcripts commonly associated with cardiac hypertrophy.