Abstract
Epigenetic modification, particularly changes in DNA methylation at gene promoters, is implicated in the pathogenesis of atherosclerosis. However, the analysis of DNA methylation in atherosclerosis has been limited to a few selected candidate genes. In this study, we therefore performed a genome-wide analysis of DNA methylation in the atherosclerotic human aorta. A total of 48 post-mortem human aortic intima specimens were examined. To avoid the effects of interindividual variation, we performed intraindividual paired comparisons between atheromatous plaque lesions and corresponding plaque-free tissue for 24 subjects. Bisulfite-modified genomic DNA was analyzed for DNA methylation with a specific microarray (Illumina HumanMethylation450 BeadChip). We compensated for multiple comparisons by applying Bonferroni's correction for statistical significance of association. DNA methylation was significantly (P<1.03x10⁻&sup7;) reduced at 15 CpG sites in 14 genes and increased at 30 CpG sites in 22 genes in atheromatous plaque compared with plaque-free intima. Three of the hypomethylated genes [Drosophila headcase (HECA), early B-cell factor 1 (EBF1) and nucleotide-binding oligomerization domain containing 2 (NOD2)] and three of the hypermethylated genes [human mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4), zinc finger E-box binding homeobox 1 (ZEB1) and FYN] were previously been implicated in atherosclerosis. The overexpression of HECA, EBF1 or NOD2 or the suppression of MAP4K4, ZEB1 or FYN expression in cultured HEK293 cells resulted in significant (P<4.80x10⁻&sup7;) changes in the expression of atherosclerosis-related genes, as determined with an expression microarray (Illumina HumanHT-12 v4 Expression BeadChip). Our findings suggested that HECA, EBF1 and NOD2 were significantly hypomethylated, whereas MAP4K4, ZEB1 and FYN were hypermethylated, in atheromatous plaque lesions compared with plaque-free intima. Epigenetic mechanisms may thus contribute to the pathogenesis of atherosclerosis.