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 months. 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-month-old control and FHC alpha-TM175 and alpha-TM180 ventricular tissue. Results show that 754 genes (from a total of 22,600) were differentially expressed between the 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." Keywords: Cardiac hypertrophy, Tropomyosin, Mutation, Transgenic mouse, Microarray Samples used for hybridization consisted of pooled (P) and non-pooled (NP) RNA extracts from the three groups namely NTG, alpha-TM175 and alpha-TM180. Ten hybridization experiments were performed in which each genotypic group was represented by two or more non-pooled (NP) individual RNA extracts and one pooled (P) sample that resulted from combining 20 individual heart extracts