title: Peroxisome proliferator-activated receptor-gamma ligands inhibit TGF-beta 1-induced fibronectin expression in glomerular mesangial cells.
abstract: The thiazolidinedione (TZD) class of antidiabetic drugs, which are ligands for peroxisome proliferator-activated receptor (PPAR)-gamma, has been shown to possess potent anti-inflammatory and antineoplastic actions. Here, we show in mesangial cells that PPAR-gamma agonists inhibit fibronectin expression by transforming growth factor (TGF)-beta 1. TGF-beta 1 enhanced fibronectin mRNA expression, and this enhancement was abrogated by pretreatment with pioglitazone. Electrophoretic mobility shift assay identified that pioglitazone inhibited TGF-beta 1-induced DNA binding of activator protein-1 (AP-1). Pioglitazone inhibited AP-1 reporter activity but not Smad binding elements reporter activity without affecting TGF-beta 1-induced activation of mitogen-activated protein kinases (MAPKs) or Smad2. PPAR-gamma overexpression inhibited TGF-beta 1-induced fibronectin expression as well as the activation of AP-1. 15-Deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), a natural PPAR-gamma ligand, also inhibited TGF-beta1-induced fibronectin expression by suppressing AP-1 activation by TGF-beta 1. 15d-PGJ(2) inhibited the TGF-beta 1-induced MAPK activation. Dominant-negative PPAR-gamma (Delta PPAR-gamma) completely abrogated the inhibitory effect of pioglitazone and incompletely blocked its effect of 15d-PGJ(2) on TGF-beta 1-induced AP-1 reporter activity. Delta PPAR-gamma overexpression did not affect the inhibitory effect of 15d-PGJ(2) on TGF-beta 1-induced MAPK activation. In conclusion, pioglitazone inhibits TGF-beta 1-induced fibronectin expression by inhibiting AP-1 activation dependent on PPAR-gamma, while 15d-PGJ(2) acts through a dual mechanism independent of and dependent on PPAR-gamma activation in mouse mesangial cells.
authors.affiliation: Department of Medicine, Shiga University of Medical Science, Seta, Otsu, Shiga, Japan.
authors.forename: Baoliang
authors.initials: B
authors.lastname: Guo
authors.forename: Daisuke
authors.initials: D
authors.lastname: Koya
authors.forename: Motohide
authors.initials: M
authors.lastname: Isono
authors.forename: Toshiro
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Atsunori
authors.initials: A
authors.lastname: Kashiwagi
authors.forename: Masakazu
authors.initials: M
authors.lastname: Haneda
mesh_terms: D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002478:Cells, Cultured; D016384:Consensus Sequence; D017931:DNA Primers; D005353:Fibronectins / Q000235:genetics*; D005920:Glomerular Mesangium / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D008024:Ligands; D051379:Mice; D008822:Mice, Transgenic; D000077205:Pioglitazone; D012333:RNA, Messenger / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013539:Simian virus 40 / Q000235:genetics; D045162:Thiazolidinediones / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D017931:DNA Primers; D005353:Fibronectins; D007004:Hypoglycemic Agents; D008024:Ligands; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins; D045162:Thiazolidinediones; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D000077205:Pioglitazone