EZH2Mediated ABCA1Promoter DNA And Histone Methylation Contributes To Atherosclerosis Development

Objective: The membrane transporter ATP-binding cassette transporterA1(ABCA1)is vital to cholesterol homeostasis. However, epigenetic regulation of ABCA1affectfoam cell formation and atherosclerosis development have not yet been unclear. Thepurpose this study is to determine whether and how epigenetic modification affectsmacrophage ABCA1expression and atherosclerosis.Methods: THP-1, RAW264.7cells were treated with EZH2or EZH2shRNA. Thelipid accumulation was examined by Oil Red O staining. The atherosclerosis lesionsof apoE/mice were examined by HE, Oil Red O and Masson staining. The mRNAexpression of ABCA1tested by real-time quantitative PCR, and the proteinexpression of ABCA1were tested by Western blot. Bioinformatics analyses predicteda large CpG island (CGI) located in the promoter region of ABCA1. Accordingly, thebinding of DNMT1, MeCP2to ABCA1promoter is determined by ChIP, aftershDNMT1transfected we examined the effect of EZH2on ABCA1expression andcholesterol efflux.Results: Our results have shown that histone DNA methylation and H3K27methylation induced macrophage derived foam cell formation and promotedatherosclerosis in apoE/mice. Using bioinformatics analyses, we found that a largeCpG island (CGI) located in the promoter region of ABCA1. Enhancer of zestehomolog2(EZH2) and DNA methyltransferase1(DNMT1) downregulates ABCA1mRNA and protein expression in THP-1and RAW264.7macrophages.Pharmacological inhibition of DNMT1or knockdown of DNMT1preventsdown-regulation of macrophage ABCA1. These results indicate that DNA methylation down-regulates ABCA1expression. Polycomb protein EZH2induces DNMT1expression and recruitment. EZH2stimulates binding of DNMT1, thus inducedABCA1gene DNA methylation and atherosclerosis. Similarly, knockdown of EZH2negates DNMT1induced down-regulation of ABCA1in macrophages. Finally,overexpression of EZH2stimulates DNMT1induced ABCA1gene promoter DNAmethylation and atherosclerosis.Conclusions: EZH2induced epigenetic modification caused foam cell formation andatherosclerosis by downregulating ABCA1expression via histone H3K27methylationassociated with DNA methylation.