Essential role of Smad3 in the inhibition of inflammation-induced PPARbeta/delta expression

EMBO J. 2004 Oct 27;23(21):4211-21. doi: 10.1038/sj.emboj.7600437. Epub 2004 Oct 7.

Abstract

Wound healing proceeds by the concerted action of a variety of signals that have been well identified. However, the mechanisms integrating them and coordinating their effects are poorly known. Herein, we reveal how PPARbeta/delta (PPAR: peroxisome proliferator-activated receptor) follows a balanced pattern of expression controlled by a crosstalk between inflammatory cytokines and TGF-beta1. Whereas conditions that mimic the initial inflammatory events stimulate PPARbeta/delta expression, TGF-beta1/Smad3 suppresses this inflammation-induced PPARbeta/delta transcription, as seen in the late re-epithelialization/remodeling events. This TGF-beta1/Smad3 action involves an inhibitory effect on AP-1 activity and DNA binding that results in an inhibition of the AP-1-driven induction of the PPARbeta/delta promoter. As expected from these observations, wound biopsies from Smad3-null mice showed sustained PPARbeta expression as compared to those of their wild-type littermates. Together, these findings suggest a mechanism for setting the necessary balance between inflammatory signals, which trigger PPARbeta/delta expression, and TGF-beta1/Smad3 that governs the timely decrease of this expression as wound healing proceeds to completion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cytokines / genetics
  • Cytokines / immunology
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Gene Expression Regulation*
  • Genes, Reporter
  • Inflammation / immunology
  • Inflammation / metabolism*
  • Mice
  • Mice, Knockout
  • Nuclear Proteins / metabolism
  • PPAR delta / genetics
  • PPAR delta / immunology*
  • PPAR delta / metabolism*
  • PPAR-beta / genetics
  • PPAR-beta / metabolism*
  • Promoter Regions, Genetic
  • Protein Binding
  • Proto-Oncogene Proteins c-jun / metabolism
  • Signal Transduction
  • Smad3 Protein
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transforming Growth Factor beta / metabolism
  • Transforming Growth Factor beta1
  • Wound Healing / physiology

Substances

  • Cytokines
  • DNA-Binding Proteins
  • Nuclear Proteins
  • PPAR delta
  • PPAR-beta
  • Proto-Oncogene Proteins c-jun
  • Smad3 Protein
  • Smad3 protein, mouse
  • Tgfb1 protein, mouse
  • Trans-Activators
  • Transforming Growth Factor beta
  • Transforming Growth Factor beta1