National Center for
4JAZ: Crystal Structure Of The Complex Between Ppargamma Lbd And Trans- Resveratrol
Chembiochem (2014) 15 p.1154-1160
Resveratrol, a modulator of several signaling proteins, can exert off-target effects involving the peroxisome proliferator-activated receptor (PPAR) transcription factors. However, evidence for the direct interaction between this polyphenol and PPARs is lacking. Here, we addressed the hypothesis that resveratrol and its metabolites control aspects of PPAR transcriptional activity through direct interaction with PPARs. Bioaffinity chromatographic studies with the immobilized ligand-binding domains (LBDs) of PPARgamma and PPARalpha and isothermal titration calorimetry allowed the binding affinities of resveratrol, resveratrol 3-O-glucuronide, resveratrol 4-O-glucuronide, and resveratrol 3-O-sulfate to both PPAR-LBDs to be determined. Interaction of resveratrol, resveratrol 3-O-glucuronide, and resveratrol 4-O-glucuronide with PPARgamma-LBD occurred with binding affinities of 1.4, 1.1, and 0.8 muM, respectively, although only resveratrol bound to the PPARalpha-LBD with a binding affinity of 2.7 muM. Subsequently, X-ray crystallographic studies were carried out to characterize resveratrol binding to the PPARgamma-LBD at the molecular level. The electron density map from the crystal structure of the complex between PPARgamma-LBD and resveratrol revealed the presence of one molecule of resveratrol bound to the LBD of PPARgamma, with the ligand occupying a position close to that of other known PPARgamma ligands. Transactivation assays were also performed in HepG2 cells, with the results showing that resveratrol was not a PPAR agonist but instead was able to displace rosiglitazone from PPARgamma and Wy-14643 from PPARalpha with IC50 values of (27.4+/-1.8) muM and (31.7+/-2.5) muM, respectively. We propose that resveratrol acts as a PPAR antagonist through its direct interaction with PPARgamma and PPARalpha.