Alternation of histone and DNA methylation in human atherosclerotic carotid plaques

Abstract

Little is known about epigenetics and its possible role in atherosclerosis. We here analysed histone and DNA methylation and the expression of corresponding methyltransferases in early and advanced human atherosclerotic carotid lesions in comparison to healthy carotid arteries. Western Blotting was performed on carotid plaques from our biobank with early (n=60) or advanced (n=60) stages of atherosclerosis and healthy carotid arteries (n=12) to analyse di-methylation patterns of histone H3 at positions K4, K9 and K27. In atherosclerotic lesions, di-methylation of H3K4 was unaltered and that of H3K9 and H3K27 significantly decreased compared to control arteries. Immunohistochemistry revealed an increased appearance of di-methylated H3K4 in smooth muscle cells (SMCs), a decreased expression of di-methylated H3K9 in SMCs and inflammatory cells, and reduced di-methylated H3K27 in inflammatory cells in advanced versus early atherosclerosis. Expression of corresponding histone methyltransferases MLL2 and G9a was increased in advanced versus early atherosclerosis. Genomic DNA hypomethylation, as determined by PCR for methylated LINE1 and SAT-alpha, was observed in early and advanced plaques compared to control arteries and in cell-free serum of patients with high-grade carotid stenosis compared to healthy volunteers. In contrast, no differences in DNA methylation were observed in blood cells. Expression of DNA-methyltransferase DNMT1 was reduced in atherosclerotic plaques versus controls, DNMT3A was undetectable, and DNMT3B not altered. DNA-demethylase TET1 was increased in atherosclerosisc plaques. The extent of histone and DNA methylation and expression of some corresponding methyltransferases are significantly altered in atherosclerosis, suggesting a possible contribution of epigenetics in disease development.

Effect of MTHFR Gene Polymorphism Impact on Atherosclerosis via Genome-Wide Methylation

“…Our results show that atherosclerosis patients presented lower genome-wide methylation level than in healthy controls, which is consistent with previous reports [ 9 , 21 ]. Our results further confirm that atherosclerosis occurrence is closely related to genome-wide methylation level reduction and that MTHFR C667T loci polymorphism was associated with AS occurrence.…”

“…DNA methylation is also related to AS [ 8 ]. Genome-wide methylation level was lower in AS patients [ 9 ] and affects atherosclerotic plaque formation in ApoE −/− mice [ 10 , 11 ]. Studies found that vascular smooth muscle cell genome DNA methylation level was regulated by Hcy [ 12 ].…”

Hypoxia-Inducible Histone Lysine Demethylases: Impact on the Aging Process and Age-Related Diseases

“…This may cause detrimental effects, which are linked to epigenetic changes, e.g. in fibrotic lesions of myocardium and atherosclerotic arteries [ 188 , 190 , 191 ]. Recent epigenetic studies have clearly shown that the aging process is associated with significant changes in the chromatin landscape [ 192 - 194 ].…”

“…Recently, many studies have revealed that there are remarkable epigenetic changes in atherosclerotic vessels, e.g. reduced levels of H3K9me2,3 and H3K27me2,3 [ 190 , 191 ]. Epigenetic alterations have also been reported in cardiovascular diseases [ 202 ] as well as in obesity and metabolic syndrome [ 203 ].…”

Histone acetylation and histone acetyltransferases show significant alterations in human abdominal aortic aneurysm

“…For example, genomic DNA isolated from human atherosclerotic lesions was found to be hypomethylated [ 12 ]. Recently, our group demonstrated significant differences in histone and DNA methylation and the expression of corresponding methyltransferases at different stages of atherosclerosis in carotid arteries [ 13 ]. Krishna et al have hypothesized that epigenetic mechanisms may also play a role in the pathogenesis of AAA [ 14 ].…”