title: Regulation of the growth arrest and DNA damage-inducible gene 45 (GADD45) by peroxisome proliferator-activated receptor gamma in vascular smooth muscle cells.
abstract: Peroxisome proliferator-activated receptor (PPAR) gamma is activated by thiazolidinediones (TZDs), widely used as insulin-sensitizing agents for the treatment of type 2 diabetes. TZDs have been shown to induce apoptosis in a variety of mammalian cells. In vascular smooth muscle cells (VSMCs), proliferation and apoptosis may be competing processes during the formation of restenotic and atherosclerotic lesions. The precise molecular mechanisms by which TZDs induce apoptosis in VSMCs, however, remain unclear. In the present study, we demonstrate that the TZDs rosiglitazone (RSG), troglitazone (TRO), and a novel non-TZD partial PPARgamma agonist (nTZDpa) induce caspase-mediated apoptosis of human coronary VSMCs. Induction of VSMC apoptosis correlated closely with an upregulation of growth arrest and DNA damage-inducible gene 45 (GADD45) mRNA expression and transcription, a well-recognized modulator of cell cycle arrest and apoptosis. Using adenoviral-mediated overexpression of a constitutively active PPARgamma mutant and the irreversible PPARgamma antagonist GW9662, we provide evidence that PPARgamma ligands induce caspase-mediated apoptosis and GADD45 expression through a receptor-dependent pathway. Deletion analysis of the GADD45 promoter revealed that a 153-bp region between -234 and -81 bp proximal to the transcription start site, containing an Oct-1 element, was crucial for the PPARgamma ligand-mediated induction of the GADD45 promoter. PPARgamma activation induced Oct-1 protein expression and DNA binding and stimulated activity of a reporter plasmid driven by multiple Oct-1 elements. These findings suggest that activation of PPARgamma can lead to apoptosis and growth arrest in VSMCs, at least in part, by inducing Oct-1-mediated transcription of GADD45. The full text of this article is available online at http://www.circresaha.org.
authors.affiliation: Division of Endocrinology, Diabetes and Hypertension and The Gonda (Goldschmied) Diabetes Center, David Geffen School of Medicine, University of California, Los Angeles, Calif 90095, USA.
authors.forename: Dennis
authors.initials: D
authors.lastname: Bruemmer
authors.forename: Fen
authors.initials: F
authors.lastname: Yin
authors.forename: Joey
authors.initials: J
authors.lastname: Liu
authors.forename: Joel P
authors.initials: JP
authors.lastname: Berger
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakai
authors.forename: Florian
authors.initials: F
authors.lastname: Blaschke
authors.forename: Eckart
authors.initials: E
authors.lastname: Fleck
authors.forename: Andre J
authors.initials: AJ
authors.lastname: Van Herle
authors.forename: Barry M
authors.initials: BM
authors.lastname: Forman
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Law
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001665:Binding Sites / Q000235:genetics; D015152:Blotting, Northern; D061945:Caspase Inhibitors; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002839:Chromans / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D051863:Host Cell Factor C1; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation; D050811:Octamer Transcription Factor-1; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D000077154:Rosiglitazone; D013844:Thiazoles / Q000494:pharmacology; D045162:Thiazolidinediones; D014157:Transcription Factors / Q000819:agonists / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects; D000077288:Troglitazone; D000097642:GADD45 Proteins
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D002839:Chromans; D015853:Cysteine Proteinase Inhibitors; D004268:DNA-Binding Proteins; D051863:Host Cell Factor C1; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases; D050811:Octamer Transcription Factor-1; D011506:Proteins; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D000077154:Rosiglitazone; D013844:Thiazoles; D045162:Thiazolidinediones; D014157:Transcription Factors; D000077288:Troglitazone; D000097642:GADD45 Proteins; C497692:HCFC1 protein, human; C494165:POU2F1 protein, human; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone