Histone Methyltransferase Enhancer of Zeste Homolog 2-Mediated ABCA1 Promoter DNA Methylation Contributes to the Progression of Atherosclerosis

PLoS One. 2016 Jun 13;11(6):e0157265. doi: 10.1371/journal.pone.0157265. eCollection 2016.

Abstract

ATP-binding cassette transporter A1 (ABCA1) plays a critical role in maintaining cellular cholesterol homeostasis. The purpose of this study is to identify the molecular mechanism(s) underlying ABCA1 epigenetic modification and determine its potential impact on ABCA1 expression in macrophage-derived foam cell formation and atherosclerosis development. DNA methylation induced foam cell formation from macrophages and promoted atherosclerosis in apolipoprotein E-deficient (apoE-/-) mice. Bioinformatics analyses revealed a large CpG island (CGI) located in the promoter region of ABCA1. Histone methyltransferase enhancer of zeste homolog 2 (EZH2) downregulated ABCA1 mRNA and protein expression in THP-1 and RAW264.7 macrophage-derived foam cells. Pharmacological inhibition of DNA methyltransferase 1 (DNMT1) with 5-Aza-dC or knockdown of DNMT1 prevented the downregulation of macrophage ABCA1 expression, suggesting a role of DNA methylation in ABCA1 expression. Polycomb protein EZH2 induced DNMT1 expression and methyl-CpG-binding protein-2 (MeCP2) recruitment, and stimulated the binding of DNMT1 and MeCP2 to ABCA1 promoter, thereby promoting ABCA1 gene DNA methylation and atherosclerosis. Knockdown of DNMT1 inhibited EZH2-induced downregulation of ABCA1 in macrophages. Conversely, EZH2 overexpression stimulated DNMT1-induced ABCA1 gene promoter methylation and atherosclerosis. EZH2-induced downregulation of ABCA1 gene expression promotes foam cell formation and the development of atherosclerosis by DNA methylation of ABCA1 gene promoter.

MeSH terms

  • ATP Binding Cassette Transporter 1 / genetics*
  • ATP Binding Cassette Transporter 1 / metabolism
  • Animals
  • Apolipoproteins E / genetics
  • Atherosclerosis / genetics*
  • Atherosclerosis / metabolism
  • Atherosclerosis / pathology*
  • Cell Line
  • Cholesterol / analysis
  • Cholesterol / metabolism
  • DNA Methylation*
  • Down-Regulation
  • Enhancer of Zeste Homolog 2 Protein / genetics
  • Enhancer of Zeste Homolog 2 Protein / metabolism*
  • Epigenesis, Genetic
  • Gene Deletion
  • Humans
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Promoter Regions, Genetic*
  • RAW 264.7 Cells

Substances

  • ABCA1 protein, mouse
  • ATP Binding Cassette Transporter 1
  • Apolipoproteins E
  • Cholesterol
  • Enhancer of Zeste Homolog 2 Protein

Grants and funding

The authors gratefully acknowledge the financial support from the National Natural Sciences Foundation of China (81370377 and 81300158), the Hunan Provincial Natural Science Foundation of China (14JJ2091), the Aid Program for Science and Technology Department of Human Province (2015JC3083), the Scientific Research Fund of Hunan Provincial Education Department (12C0339), the start-up funds for Ph.Ds in University of South China (2014XQD37), Zhengxiang scholar program (prof. Xiangyang Tang) of the University of South China and the construct program of the key discipline in Hunan Province. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.