文摘
Peroxisome proliferator-activated receptor 纬 (PPAR纬) is a ligand-activated transcription factor that plays an important role in adipogenesis and glucose metabolism. The ligand-binding pocket (LBP) of PPAR纬 has a large Y-shaped cavity with multiple subpockets where multiple ligands can simultaneously bind and cooperatively activate PPAR纬. Focusing on this unique property of the PPAR纬 LBP, we describe a novel two-step cell-based strategy to develop PPAR纬 ligands. First, a combination of ligands that cooperatively activates PPAR纬 was identified using a luciferase reporter assay. Second, hybrid ligands were designed and synthesized. For proof of concept, we focused on covalent agonists, which activate PPAR纬 through a unique activation mechanism regulated by a covalent linkage with the Cys285 residue in the PPAR纬 LBP. Despite their biological significance and pharmacological potential, few covalent PPAR纬 agonists are known except for endogenous fatty acid metabolites. With our strategy, we determined that plant-derived cinnamic acid derivatives cooperatively activated PPAR纬 by combining with GW9662, an irreversible antagonist. GW9662 covalently reacts with the Cys285 residue. A docking study predicted that a cinnamic acid derivative can bind to the open cavity in GW9662-bound PPAR纬 LBP. On the basis of the putative binding mode, structures of both ligands were linked successfully to create a potent PPAR纬 agonist, which enhanced the transactivation potential of PPAR纬 at submicromolar levels through covalent modification of Cys285. Our approach could lead to the discovery of novel high-potency PPAR纬 agonists.