gsk-2816126 and Fibrosis

Myocardial fibrosis is a common pathological companion of various cardiovascular diseases. To date, the role of enhancer of zeste homolog 2 (EZH2) in cancer has been well demonstrated including in renal carcinoma and its inhibitors have entered the stage of phase I/II clinical trials. However, the precise mechanism of EZH2 in cardiac diseases is largely unclear. In the current study, we first found that EZH2 expression was increased in Ang-II-treated cardiac fibroblasts (CFs) and mouse heart homogenates following isoproterenol (ISO) administration for 21 days, respectively. Ang-II induces CFs activation and increased collagen-I, collagen-III, α-SMA, EZH2, and trimethylates lysine 27 on histone 3 (H3K27me3) expressions can be reversed by EZH2 inhibitor (GSK126) and EZH2 siRNA. The ISO-induced cardiac hypertrophy, and fibrosis in vivo which were also related to the upregulation of EZH2 and its downstream target, H3K27me3, could be recovered by GSK126. Furthermore, the upregulation of EZH2 induces the decrease of paired box 6 (PAX6) and C-X-C motif ligand 10 (CXCL10) "which" were also reversed by GSK126 treatment. In summary, the present evidence strongly suggests that GSK126 could be a therapeutic intervention, blunting the development and progression of myocardial fibrosis in an EZH2-PAX6-CXCL10-dependent manner.

Topics: Animals; Enhancer of Zeste Homolog 2 Protein; Epigenesis, Genetic; Fibrosis; Histones; Mice; PAX6 Transcription Factor

Systemic sclerosis (SSc) is characterised by autoimmune activation, tissue and vascular fibrosis in the skin and internal organs. Tissue fibrosis is driven by myofibroblasts, that are known to maintain their phenotype in vitro, which is associated with epigenetically driven trimethylation of lysine 27 of histone 3 (H3K27me3).. Full-thickness skin biopsies were surgically obtained from the forearms of 12 adult patients with SSc of recent onset. Fibroblasts were isolated and cultured in monolayers and protein and RNA extracted. HOX transcript antisense RNA (HOTAIR) was expressed in healthy dermal fibroblasts by lentiviral induction employing a vector containing the specific sequence. Gamma secretase inhibitors were employed to block Notch signalling. Enhancer of zeste 2 (EZH2) was blocked with GSK126 inhibitor.. SSc myofibroblasts in vitro and SSc skin biopsies in vivo display high levels of HOTAIR, a scaffold long non-coding RNA known to direct the histone methyltransferase EZH2 to induce H3K27me3 in specific target genes. Overexpression of HOTAIR in dermal fibroblasts induced EZH2-dependent increase in collagen and α-SMA expression in vitro, as well as repression of miRNA-34A expression and consequent NOTCH pathway activation. Consistent with these findings, we show that SSc dermal fibroblast display decreased levels of miRNA-34a in vitro. Further, EZH2 inhibition rescued miRNA-34a levels and mitigated the profibrotic phenotype of both SSc and HOTAIR overexpressing fibroblasts in vitro.. Our data indicate that the EZH2-dependent epigenetic phenotype of myofibroblasts is driven by HOTAIR and is linked to miRNA-34a repression-dependent activation of NOTCH signalling.

Topics: Amyloid Precursor Protein Secretases; Enhancer of Zeste Homolog 2 Protein; Epigenesis, Genetic; Fibroblasts; Fibrosis; Histone Code; Humans; Indoles; MicroRNAs; Myofibroblasts; Phenotype; Pyridones; Receptors, Notch; RNA, Long Noncoding; Scleroderma, Systemic; Signal Transduction; Skin

Angiotensin II (Ang-II)-induced fibroblast differentiation plays an important role in the development of atrial fibrosis and atrial fibrillation (AF). Here, we show that the expression of the histone methyltransferase enhancer of zeste homolog 2 (EZH2) is increased in atrial muscle and atrial fibroblasts in patients with AF, accompanied by significant atrial fibrosis and atrial fibroblast differentiation. In addition, EZH2 is induced in murine models of atrial fibrosis. Furthermore, either pharmacological GSK126 inhibition or molecular silencing of EZH2 can inhibit the differentiation of atrial fibroblasts and the ability to produce ECM induced by Ang-II. Simultaneously, inhibition of EZH2 can block the Ang-II-induced migration of atrial fibroblasts. We found that EZH2 promotes fibroblast differentiation mainly through the Smad signaling pathway and can form a transcription complex with Smad2 to bind to the promoter region of the ACTA2 gene. Finally, our in vivo experiments demonstrated that the EZH2 inhibitor GSK126 significantly inhibited Ang-II-induced atrial enlargement and fibrosis and reduced AF vulnerability. Our results demonstrate that targeting EZH2 or EZH2-regulated genes might present therapeutic potential in AF.

Topics: Angiotensin II; Animals; Atrial Fibrillation; Disease Models, Animal; Dogs; Enhancer of Zeste Homolog 2 Protein; Female; Fibroblasts; Fibrosis; Gene Expression Regulation; Heart Atria; Humans; Indoles; Male; Mice; Middle Aged; Pyridones