Transcriptional and epigenetic mechanisms underlying enhanced in vitro adipocyte differentiation by the brominated flame retardant BDE-47

Environ Sci Technol. 2014 Apr 1;48(7):4110-9. doi: 10.1021/es405524b. Epub 2014 Mar 11.

Abstract

Recent studies suggest that exposure to endocrine-disrupting compounds (EDCs) may play a role in the development of obesity. EDCs such as the flame retardant 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) have been shown to enhance adipocyte differentiation in the murine 3T3-L1 model. The mechanisms by which EDCs direct preadipocytes to form adipocytes are poorly understood. Here, we examined transcriptional and epigenetic mechanisms underlying the induction of in vitro adipocyte differentiation by BDE-47. Quantitative high content microscopy revealed concentration-dependent enhanced adipocyte differentiation following exposure to BDE-47 or the antidiabetic drug troglitazone (TROG). BDE-47 modestly activated the key adipogenic transcription factor peroxisome proliferator-activated receptor gamma (PPARγ) in COS7 cells, transiently transfected with a GAL4 reporter construct. Increased gene expression was observed for Pparγ2, leptin (Lep), and glucose-6-phophatase catalytic subunit (G6pc) in differentiated 3T3-L1 cells after BDE-47 exposure compared to TROG. Methylation-sensitive high resolution melting (MS-HRM) revealed significant demethylation of three CpG sites in the Pparγ2 promoter after exposure to both BDE-47 and TROG in differentiated 3T3-L1 cells. This study shows the potential of BDE-47 to induce adipocyte differentiation through various mechanisms that include Pparγ2 gene induction and promoter demethylation accompanied by activation of PPARγ, and possible disruption of glucose homeostasis and IGF1 signaling.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 3T3-L1 Cells
  • Adipocytes / cytology*
  • Adipocytes / drug effects
  • Adipocytes / metabolism*
  • Adipogenesis / drug effects
  • Adipogenesis / genetics
  • Animals
  • COS Cells
  • Cell Differentiation / drug effects
  • Cell Differentiation / genetics*
  • Chlorocebus aethiops
  • CpG Islands / genetics
  • DNA Methylation / drug effects
  • DNA Methylation / genetics
  • Epigenesis, Genetic / drug effects*
  • Flame Retardants / toxicity*
  • Halogenated Diphenyl Ethers / toxicity*
  • Humans
  • Mice
  • Nucleic Acid Denaturation / drug effects
  • PPAR gamma / genetics
  • PPAR gamma / metabolism
  • Promoter Regions, Genetic / genetics
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Retinoid X Receptor alpha / genetics
  • Retinoid X Receptor alpha / metabolism
  • Transcription, Genetic / drug effects*
  • Transcriptional Activation / drug effects
  • Transcriptional Activation / genetics

Substances

  • Flame Retardants
  • Halogenated Diphenyl Ethers
  • PPAR gamma
  • RNA, Messenger
  • Retinoid X Receptor alpha
  • 2,2',4,4'-tetrabromodiphenyl ether