Bromodomain-containing protein 2 induces insulin resistance via the mTOR/Akt signaling pathway and an inflammatory response in adipose tissue

Cell Signal. 2017 Jan:30:92-103. doi: 10.1016/j.cellsig.2016.11.011. Epub 2016 Nov 16.

Abstract

Insulin resistance is a major metabolic abnormality in a large majority of patients with type II diabetes. Bromodomain-containing protein 2 (Brd2), a transcriptional co-activator/co-repressor with switch mating type/sucrose non-fermenting (SWI/SNF)-like functions that regulates chromatin, suppresses adipocyte differentiation and regulates pancreatic β-cell biology. However, the effects of Brd2 on insulin resistance remain unknown. Here, overexpression of Brd2 in white adipose tissue of wild-type (WT) mice led to insulin resistance. Brd2 overexpression induced the expression of nuclear Factor-κΒ (NF-κΒ) target genes, mainly involving proinflammatory and chemotactic factors, in adipocytes. Furthermore, it decreased the expression of DEP domain containing mTOR-interacting protein (Deptor) to enhance mechanistic target of rapamycin (mTOR) signaling, thus blocking insulin signaling. Collectively, these results provided evidence for a novel role of Brd2 in chronic inflammation and insulin resistance, suggesting its potential in improving insulin resistance and treating metabolic disorders.

Keywords: Brd2; Inflammation; Insulin resistance; Insulin signaling pathway; mTOR signaling.

MeSH terms

  • 3T3-L1 Cells
  • Adipocytes / metabolism
  • Adipose Tissue, White / metabolism*
  • Animals
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Gene Expression Regulation
  • Gene Knockdown Techniques
  • Glucose / metabolism
  • Inflammation / genetics
  • Inflammation / pathology*
  • Insulin / metabolism
  • Insulin Resistance* / genetics
  • Intracellular Signaling Peptides and Proteins / genetics
  • Mechanistic Target of Rapamycin Complex 1 / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Models, Biological
  • NF-kappa B / metabolism
  • Promoter Regions, Genetic / genetics
  • Protein Binding / genetics
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Signal Transduction* / genetics
  • TOR Serine-Threonine Kinases / metabolism*
  • Transcription Factors
  • Transcription, Genetic

Substances

  • Brd2 protein, mouse
  • Chromosomal Proteins, Non-Histone
  • Insulin
  • Intracellular Signaling Peptides and Proteins
  • NF-kappa B
  • Transcription Factors
  • deptor protein, mouse
  • Mechanistic Target of Rapamycin Complex 1
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Glucose