title: The dipeptide H-Trp-Glu-OH shows highly antagonistic activity against PPARgamma: bioassay with molecular modeling simulation.
abstract: The peroxisome proliferator-activated receptor gamma (PPARgamma) is an important therapeutic drug target for several conditions, including diabetes, inflammation, dyslipidemia, hypertension, and cancer. It is shown that an antagonist or partial agonist of PPARgamma has attractive potential applications in the discovery of novel antidiabetic agents that may retain efficacious insulin-sensitizing properties and minimize potential side effects. In this work, the dipeptide H-Trp-Glu-OH (G3335) was discovered to be a novel PPARgamma antagonist. Biacore 3000 results based on the surface plasmon resonance (SPR) technique showed that G3335 exhibits a highly specific binding affinity against PPARgamma (K(D) = 8.34 microM) and is able to block rosiglitazone, a potent PPARgamma agonist, in the stimulation of the interaction between the PPARgamma ligand-binding domain (LBD) and RXRalpha-LBD. Yeast two-hybrid assays demonstrated that G3335 exhibits strong antagonistic activity (IC50 = 8.67 microM) in perturbing rosiglitazone in the promotion of the PPARgamma-LBD-CBP interaction. Moreover, in transactivation assays, G3335 was further confirmed as an antagonist of PPARgamma in that G3335 could competitively bind to PPARgamma against 0.1 microM rosiglitazone to repress reporter-gene expression with an IC50 value of 31.9 muM. In addition, homology modeling and molecular-docking analyses were performed to investigate the binding mode of PPARgamma-LBD with G3335 at the atomic level. The results suggested that residues Cys285, Arg288, Ser289, and His449 in PPARgamma play vital roles in PPARgamma-LBD-G3335 binding. The significance of Cys285 for PPARgamma-LBD-G3335 interaction was further demonstrated by PPARgamma point mutation (PPARgamma-LBD-Cys285Ala). It is hoped our current work will provide a powerful approach for the discovery of PPARgamma antagonists, and that G3335 might be developed as a possible lead compound in diabetes research.
authors.affiliation: Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Ye
authors.forename: Zhen-Shan
authors.initials: ZS
authors.lastname: Zhang
authors.forename: Hai-Bin
authors.initials: HB
authors.lastname: Luo
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Shen
authors.forename: Kai-Xian
authors.initials: KX
authors.lastname: Chen
authors.forename: Xu
authors.initials: X
authors.lastname: Shen
authors.forename: Hua-Liang
authors.initials: HL
authors.lastname: Jiang
mesh_terms: D000818:Animals; D001681:Biological Assay; D019556:COS Cells; D002522:Chlorocebus aethiops; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004151:Dipeptides / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D015394:Molecular Structure; D047495:PPAR gamma / Q000819:agonists / Q000037:antagonists & inhibitors*; D000077154:Rosiglitazone; D012680:Sensitivity and Specificity; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance / Q000379:methods; D045162:Thiazolidinediones / Q000037:antagonists & inhibitors / Q000494:pharmacology; D013997:Time Factors; D020798:Two-Hybrid System Techniques
chemical_list: D004151:Dipeptides; C509179:H-tryptophyl-hydroxyglutamine; D047495:PPAR gamma; D045162:Thiazolidinediones; D000077154:Rosiglitazone