MeCP2 epigenetically regulates alpha-smooth muscle actin in human lung fibroblasts

Academic Article

Abstract

  • Background: A critical feature for fibroblasts differentiation into myofibroblasts is the expression of alpha-smooth muscle actin (α-SMA) during the tissue injury and repair process. The epigenetic mechanism, DNA methylation, is involved in regulating α-SMA expression. It is not clear how methyl-CpG-binding protein 2 (MeCP2) interacts with CpG-rich region in α-SMA, and if the CpG methylation status would affect MeCP2 binding and regulation of α-SMA expression. Methods: The association of MeCP2 with α-SMA CpG rich region were examined by chromatin immunoprecipitation (ChIP) assays in primary fibroblasts from idiopathic pulmonary fibrosis (IPF) and non-IPF control individuals, and in the lung fibroblasts treated with profibrotic cytokine transforming growth factor β1 (TGF-β1). The regulation of α-SMA by MeCP2 was examined by knocking down MeCP2 with small interfering RNA (siRNA). To explore the effects of the DNA methylation status of the CpG rich region on α-SMA expression, the cells were treated with DNA methyltransferase inhibitor, 5′-azacytidine (5′-aza). The expression of α-SMA was examined by Western blot and quantitative polymerase chain reaction, the association with MeCP2 was assessed by ChIP assays, and the methylation status was checked by bisulfate sequencing. Results: The human lung fibroblasts with increased α-SMA showed an enriched association of MeCP2, while knockdown MeCP2 by siRNA reduced α-SMA upregulation by TGF-β1. The 5′-Aza-treated cells have decreased α-SMA expression with reduced MeCP2 association. However, bisulfite sequencing revealed that most CpG sites are unmethylated despite the different expression levels of α-SMA after being treated by TGF-β1 or 5′-aza. Conclusion: Our data indicate that the methyl-binding protein MeCP2 is critical for α-SMA expression in human lung myofibroblast, and the DNA methylation status at the CpG rich region of α-SMA is not a determinative factor for its inducible expression.
  • Authors

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    Digital Object Identifier (doi)

    Author List

  • Xiang Z; Zhou Q; Hu M; Sanders YY
  • Start Page

  • 3616
  • End Page

  • 3625
  • Volume

  • 121
  • Issue

  • 7