Abstract
OBJECTIVE: Emerging evidence supports a role for epigenetic regulation in the pathogenesis of scleroderma (SSc). We aimed to assess the role of methyl-CpG-binding protein 2 (MeCP2), a key epigenetic regulator, in fibroblast activation and fibrosis in SSc. METHODS: Dermal fibroblasts were isolated from patients with diffuse cutaneous SSc (dcSSc) and from healthy controls. MeCP2 expression was measured by qPCR and western blot. Myofibroblast differentiation was evaluated by gel contraction assay in vitro. Fibroblast proliferation was analysed by ki67 immunofluorescence staining. A wound healing assay in vitro was used to determine fibroblast migration rates. RNA-seq was performed with and without MeCP2 knockdown in dcSSc to identify MeCP2-regulated genes. The expression of MeCP2 and its targets were modulated by siRNA or plasmid. Chromatin immunoprecipitation followed by sequencing (ChIP-seq) using anti-MeCP2 antibody was performed to assess MeCP2 binding sites within MeCP2-regulated genes. RESULTS: Elevated expression of MeCP2 was detected in dcSSc fibroblasts compared with normal fibroblasts. Overexpressing MeCP2 in normal fibroblasts suppressed myofibroblast differentiation, fibroblast proliferation and fibroblast migration. RNA-seq in MeCP2-deficient dcSSc fibroblasts identified MeCP2-regulated genes involved in fibrosis, including PLAU, NID2 and ADA. Plasminogen activator urokinase (PLAU) overexpression in dcSSc fibroblasts reduced myofibroblast differentiation and fibroblast migration, while nidogen-2 (NID2) knockdown promoted myofibroblast differentiation and fibroblast migration. Adenosine deaminase (ADA) depletion in dcSSc fibroblasts inhibited cell migration rates. Taken together, antifibrotic effects of MeCP2 were mediated, at least partly, through modulating PLAU, NID2 and ADA. ChIP-seq further showed that MeCP2 directly binds regulatory sequences in NID2 and PLAU gene loci. CONCLUSIONS: This study demonstrates a novel role for MeCP2 in skin fibrosis and identifies MeCP2-regulated genes associated with fibroblast migration, myofibroblast differentiation and extracellular matrix degradation, which can be potentially targeted for therapy in SSc.