title: A novel partial agonist of peroxisome proliferator-activated receptor-gamma (PPARgamma) recruits PPARgamma-coactivator-1alpha, prevents triglyceride accumulation, and potentiates insulin signaling in vitro.
abstract: Partial agonists of peroxisome proliferator-activated receptor-gamma (PPARgamma), also termed selective PPARgamma modulators, are expected to uncouple insulin sensitization from triglyceride (TG) storage in patients with type 2 diabetes mellitus. These agents shall thus avoid adverse effects, such as body weight gain, exerted by full agonists such as thiazolidinediones. In this context, we describe the identification and characterization of the isoquinoline derivative PA-082, a prototype of a novel class of non-thiazolidinedione partial PPARgamma ligands. In a cocrystal with PPARgamma it was bound within the ligand-binding pocket without direct contact to helix 12. The compound displayed partial agonism in biochemical and cell-based transactivation assays and caused preferential recruitment of PPARgamma-coactivator-1alpha (PGC1alpha) to the receptor, a feature shared with other selective PPARgamma modulators. It antagonized rosiglitazone-driven transactivation and TG accumulation during de novo adipogenic differentiation of murine C3H10T1/2 mesenchymal stem cells. The latter effect was mimicked by overexpression of wild-type PGC1alpha but not its LXXLL-deficient mutant. Despite failing to promote TG loading, PA-082 induced mRNAs of genes encoding components of insulin signaling and adipogenic differentiation pathways. It potentiated glucose uptake and inhibited the negative cross-talk of TNFalpha on protein kinase B (AKT) phosphorylation in mature adipocytes and HepG2 human hepatoma cells. PGC1alpha is a key regulator of energy expenditure and down-regulated in diabetics. We thus propose that selective recruitment of PGC1alpha to favorable PPARgamma-target genes provides a possible molecular mechanism whereby partial PPARgamma agonists dissociate TG accumulation from insulin signaling.
authors.affiliation: Pharmaceuticals Division, Department of Vascular and Metabolic Diseases, Fa. Hoffmann-La Roche AG, CH-4070 Basel, Switzerland.
authors.forename: Elke
authors.initials: E
authors.lastname: Burgermeister
authors.forename: Astride
authors.initials: A
authors.lastname: Schnoebelen
authors.forename: Angele
authors.initials: A
authors.lastname: Flament
authors.forename: Jörg
authors.initials: J
authors.lastname: Benz
authors.forename: Martine
authors.initials: M
authors.lastname: Stihle
authors.forename: Bernard
authors.initials: B
authors.lastname: Gsell
authors.forename: Arne
authors.initials: A
authors.lastname: Rufer
authors.forename: Armin
authors.initials: A
authors.lastname: Ruf
authors.forename: Bernd
authors.initials: B
authors.lastname: Kuhn
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Märki
authors.forename: Jacques
authors.initials: J
authors.lastname: Mizrahi
authors.forename: Elena
authors.initials: E
authors.lastname: Sebokova
authors.forename: Eric
authors.initials: E
authors.lastname: Niesor
authors.forename: Markus
authors.initials: M
authors.lastname: Meyer
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D018360:Crystallography, X-Ray; D018076:DNA, Complementary / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D007546:Isoquinolines / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D047495:PPAR gamma / Q000819:agonists* / Q000737:chemistry; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D018076:DNA, Complementary; D006360:Heat-Shock Proteins; D007328:Insulin; D007546:Isoquinolines; D047495:PPAR gamma; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D014280:Triglycerides; D014409:Tumor Necrosis Factor-alpha; D005947:Glucose