GQ-16, a novel peroxisome proliferator-activated receptor ? (PPAR?) ligand, promotes insulin sensitization without weight gain.
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ABSTRACT: The recent discovery that peroxisome proliferator-activated receptor ? (PPAR?) targeted anti-diabetic drugs function by inhibiting Cdk5-mediated phosphorylation of the receptor has provided a new viewpoint to evaluate and perhaps develop improved insulin-sensitizing agents. Herein we report the development of a novel thiazolidinedione that retains similar anti-diabetic efficacy as rosiglitazone in mice yet does not elicit weight gain or edema, common side effects associated with full PPAR? activation. Further characterization of this compound shows GQ-16 to be an effective inhibitor of Cdk5-mediated phosphorylation of PPAR?. The structure of GQ-16 bound to PPAR? demonstrates that the compound utilizes a binding mode distinct from other reported PPAR? ligands, although it does share some structural features with other partial agonists, such as MRL-24 and PA-082, that have similarly been reported to dissociate insulin sensitization from weight gain. Hydrogen/deuterium exchange studies reveal that GQ-16 strongly stabilizes the ?-sheet region of the receptor, presumably explaining the compound's efficacy in inhibiting Cdk5-mediated phosphorylation of Ser-273. Molecular dynamics simulations suggest that the partial agonist activity of GQ-16 results from the compound's weak ability to stabilize helix 12 in its active conformation. Our results suggest that the emerging model, whereby "ideal" PPAR?-based therapeutics stabilize the ?-sheet/Ser-273 region and inhibit Cdk5-mediated phosphorylation while minimally invoking adipogenesis and classical agonism, is indeed a valid framework to develop improved PPAR? modulators that retain antidiabetic actions while minimizing untoward effects.
SUBMITTER: Amato AA
PROVIDER: S-EPMC3431672 | biostudies-literature | 2012 Aug
REPOSITORIES: biostudies-literature
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