Small molecule inhibitor of PPARγ acetylation promotes insulin sensitization and browning of white adipose tissue with improved safety

Abstract

The nuclear receptor PPAR{gamma} is a primary therapeutic target for insulin resistance and type 2 diabetes (T2D); however, its thiazolidinedione (TZD) class of PPAR{gamma} agonists have substantial safety concerns in clinical utilization. Genetic inhibition of PPAR{gamma} acetylation at K268 and K293 dissociates the major adverse effects of TZDs from insulin sensitization and other metabolic improvements. We therefore posit that chemical inhibition of PPAR{gamma} acetylation would elicit insulin sensitization with improved safety. Here we describe the identification of a synthetic thiopyrimidine derivative (TPMD) that acts as a small molecule inhibitor of PPAR{gamma} acetylation. TPMD improves insulin sensitivity, promotes brown remodeling of white adipose tissue (WAT), increases energy expenditure, and decreases adiposity in dietary and genetic mouse models of T2D. Importantly, TPMD is deprived of the major side effects of TZDs, including weight gain, fluid retention, cardiac hypertrophy, bone marrow adiposity, and bone loss. X-ray crystallography at 2.0 [A] resolution reveals a unique binding mode of TPMD molecules to the PPAR{gamma} ligand-binding domain and provides structural and molecular basis for the acetylation inhibitory activity of TPMD together with site-directed mutagenesis studies. These findings identify TPMD as a first-in-class compound that specifically targets PPAR{gamma} acetylation and possesses the potential of developing into a safe insulin sensitizer to treat and prevent T2D and obesity.