title: Functional consequences of cysteine modification in the ligand binding sites of peroxisome proliferator activated receptors by GW9662.
abstract: In the course of a high throughput screen to search for ligands of peroxisome proliferator activated receptor-gamma (PPARgamma), we identified GW9662 using a competition binding assay against the human ligand binding domain. GW9662 had nanomolar IC(50) versus PPARgamma and was 10- and 600-fold less potent in binding experiments using PPARalpha and PPARdelta, respectively. Pretreatment of all three PPARs with GW9662 resulted in the irreversible loss of ligand binding as assessed by scintillation proximity assay. Incubation of PPAR with GW9662 resulted in a change in the absorbance spectra of the receptors consistent with covalent modification. Mass spectrometric analysis of the PPARgamma ligand binding domain treated with GW9662 established Cys(285) as the site of covalent modification. This cysteine is conserved among all three PPARs. In cell-based reporter assays, GW9662 was a potent and selective antagonist of full-length PPARgamma. The functional activity of GW9662 as an antagonist of PPARgamma was confirmed in an assay of adipocyte differentiation. GW9662 showed essentially no effect on transcription when tested using both full-length PPARdelta and PPARalpha. Time-resolved fluorescence assays of ligand-modulated receptor heterodimerization, coactivator binding, and corepressor binding were consistent with the effects observed in the reporter gene assays. Control activators increased PPAR:RXR heterodimer formation and coactivator binding to both PPARgamma and PPARdelta. Corepressor binding was decreased. In the case of PPARalpha, GW9662 treatment did not significantly increase heterodimerization and coactivator binding or decrease corepressor binding. The experimental data indicate that GW9662 modification of each of the three PPARs results in different functional consequences. The selective and irreversible nature of GW9662 treatment, and the observation that activity is maintained in cell culture experiments, suggests that this compound may be a useful tool for elucidation of the role of PPARgamma in biological processes.
authors.affiliation: Systems Research, GlaxoSmithKline, Five Moore Drive, Research Triangle Park, NC 27709, USA.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Leesnitzer
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Parks
authors.forename: Randy K
authors.initials: RK
authors.lastname: Bledsoe
authors.forename: Jeff E
authors.initials: JE
authors.lastname: Cobb
authors.forename: Jon L
authors.initials: JL
authors.lastname: Collins
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Consler
authors.forename: Roderick G
authors.initials: RG
authors.lastname: Davis
authors.forename: Emily A
authors.initials: EA
authors.lastname: Hull-Ryde
authors.forename: James M
authors.initials: JM
authors.lastname: Lenhard
authors.forename: Lisa
authors.initials: L
authors.lastname: Patel
authors.forename: Kelli D
authors.initials: KD
authors.lastname: Plunket
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Shenk
authors.forename: Julie B
authors.initials: JB
authors.lastname: Stimmel
authors.forename: Christina
authors.initials: C
authors.lastname: Therapontos
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Willson
authors.forename: Steven G
authors.initials: SG
authors.lastname: Blanchard
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000502:physiology; D000813:Anilides / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D050882:CREB-Binding Protein; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D008024:Ligands; D009687:Nuclear Proteins / Q000378:metabolism; D056971:Nuclear Receptor Co-Repressor 1; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D047488:Retinoid X Receptors; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology
chemical_list: C457499:2-chloro-5-nitrobenzanilide; D000813:Anilides; D008024:Ligands; C539127:NCOR1 protein, human; D009687:Nuclear Proteins; D056971:Nuclear Receptor Co-Repressor 1; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; D047488:Retinoid X Receptors; D015534:Trans-Activators; D014157:Transcription Factors; D050882:CREB-Binding Protein; C494363:CREBBP protein, human; D003545:Cysteine