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A central role for G9a and EZH2 in the epigenetic silencing of cyclooxygenase‐2 in idiopathic pulmonary fibrosis
Author(s) -
Coward William R.,
FeghaliBostwick Carol A.,
Jenkins Gisli,
Knox Alan J.,
Pang Linhua
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.13-241760
Subject(s) - ezh2 , histone methyltransferase , histone h3 , epigenetics , dna methylation , histone methylation , biology , chromatin immunoprecipitation , cancer research , histone , microbiology and biotechnology , promoter , genetics , gene expression , dna , gene
Selective silencing of the cyclooxygenase‐2 (COX‐2) gene with the loss of the antifibrotic mediator prostaglandin E 2 contributes to the fibrotic process in idiopathic pulmonary fibrosis (IPF). This study explored the role of G9a‐ and enhancer of zeste homolog 2 (EZH2)‐mediated methylation of histone H3 lysine 9 (H3K9me3) and histone H3 lysine 27 (H3K27me3) in COX‐2 silencing in IPF. Chromatin immunoprecipitation (ChIP) and re‐ChIP assays demonstrated marked increases in H3K9me3, H3K27me3, and DNA methylation, together with their respective modifying enzymes G9a, EZH2, and DNA methyltransferases (Dnmts) and respective binding proteins heterochromatin protein 1 (HP1), polycomb protein complex 1 (PRC1) and methyl CpG binding protein 2 (MeCP2), at the COX‐2 promoter in lung fibroblasts from patients with IPF (F‐IPFs) compared with fibroblasts from nonfibrotic lungs. HP1, EZH2, and MeCP2 in turn were associated with additional repressive chromatin modifiers in F‐IPFs. G9a and EZH2 inhibitors and small interfering RNAs and the Dnmt1 inhibitor markedly reduced H3K9me3 (49–79%), H3K27me3 (44–81%), and DNA methylation (61–97%) at the COX‐2 promoter. These reductions were correlated with increased histone H3 and H4 acetylation, resulting in COX‐2 mRNA and protein reexpression in F‐IPFs. Our results support a central role for G9a‐ and EZH2‐mediated histone hypermethylation and a model of bidirectional, mutually reinforcing, and interdependent crosstalk between histone hypermethylation and DNA methylation in COX‐2 epigenetic silencing in IPF.—Coward, W. R., Feghali‐Bostwick, C. A., Jenkins, G., Knox, A. J., Pang, L. A central role for G9a and EZH2 in the epigenetic silencing of cyclooxygenase‐2 in idiopathic pulmonary fibrosis. FASEB J . 28, 3183–3196 (2014). www.fasebj.org