BRD7 plays an anti-inflammatory role during early acute inflammation by inhibiting activation of the NF-кB signaling pathway

Cell Mol Immunol. 2017 Oct;14(10):830-841. doi: 10.1038/cmi.2016.31. Epub 2016 Jul 4.

Abstract

Increasing evidence has shown a strong association between tumor-suppressor genes and inflammation. However, the role of BRD7 as a novel tumor suppressor in inflammation remains unknown. In this study, by observing BRD7 knockout mice for 6-12 months, we discovered that compared with BRD7+/+ mice, BRD7-/- mice were more prone to inflammation, such as external inflammation and abdominal abscess. By using mouse embryo fibroblast (MEF) cells from the BRD7 knockout mouse, an in vitro lipopolysaccharide (LPS)-stimulated MEF cell line was established. The mRNA levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), chemokine (C-X-C motif) ligand 1 (CXCL-1) and inducible nitric oxide synthase (iNOS) were significantly increased in BRD7-/- MEF cells compared with BRD7+/+ MEF cells after LPS stimulation for 1 or 6 h. In addition, the cytoplasm-to-nucleus translocation of nuclear factor kappa-B (NF-κB; p65) and an increased NF-κB reporter activity were observed in BRD7-/- MEF cells at the 1 h time point but not at the 6 h time point. Furthermore, an in vivo dextran sodium sulfate (DSS)-induced acute colitis model was created. As expected, the disease activity index (DAI) value was significantly increased in the BRD7-/- mice after DSS treatment for 1-5 days, which was demonstrated by the presence of a significantly shorter colon, splenomegaly and tissue damage. Moreover, higher expression levels of IL-6, TNF-α, p65, CXCL-1 and iNOS, and an increased level of NF-κB (p65) nuclear translocation were also found in the DSS-treated BRD7-/- mice. These findings suggest that BRD7 has an anti-inflammatory role during early acute inflammation by inhibiting activation of the NF-кB signaling pathway, which provides evidence to aid in understanding the therapeutic effects of BRD7 on inflammatory diseases.

MeSH terms

  • Animals
  • Cells, Cultured
  • Chemokine CXCL1 / metabolism
  • Chromosomal Proteins, Non-Histone / genetics
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Colitis / chemically induced
  • Colitis / immunology*
  • Dextran Sulfate
  • Fibroblasts / immunology*
  • Inflammation / immunology*
  • Interleukin-6 / metabolism
  • Lipopolysaccharides / immunology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Nitric Oxide Synthase Type II / metabolism
  • Signal Transduction
  • Transcription Factor RelA / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Brd7 protein, mouse
  • Chemokine CXCL1
  • Chromosomal Proteins, Non-Histone
  • Cxcl1 protein, mouse
  • Interleukin-6
  • Lipopolysaccharides
  • Rela protein, mouse
  • Transcription Factor RelA
  • Tumor Necrosis Factor-alpha
  • Dextran Sulfate
  • Nitric Oxide Synthase Type II
  • Nos2 protein, mouse