Title Page Mlr-1023 Is a Potent and Selective Allosteric Activator of Lyn Kinase in Vitro That Improves Glucose Tolerance in Vivo

MLR-1023 (2(1H)-Pyrimidinone, 5-(3-methylphenoxy)) is a candidate for the treatment of type 2 diabetes. The current studies were aimed at determining the mechanism by which MLR-1023 mediates glycemic control. In these studies, we showed that MLR1023 reduced blood glucose levels without increasing insulin secretion in vivo. We have further determined that MLR-1023 did not activate PPARα, δ, γ receptors or GLP-1 receptors or inhibit DPP-IV or α-glucosidase enzyme activity. However, in an in vitro broad kinase screen, MLR-1023 activated the non-receptor linked Src-related tyrosine kinase Lyn. MLR-1023 increased the Vmax of Lyn with an EC50 of 63 nM. This Lyn kinase activation was ATP binding site independent, indicating that MLR-1023 regulated the kinase through an allosteric mechanism. We have established a linkage between Lyn activation and blood glucose lowering with studies showing that the glucose lowering effects of MLR-1023 were abolished in Lyn knockout mice, consistent with existing literature linking Lyn kinase and the insulin-signaling pathway. In summary, these studies describe MLR-1023 as unique blood glucose lowering agent and that MLR-1023mediated blood glucose lowering is dependent on Lyn kinase activity. These results, coupled with the results of the accompanying paper, suggest that MLR-1023 and Lyn kinase activation may be a new treatment modality for type 2 diabetes. This article has not been copyedited and formatted. The final version may differ from this version. JPET Fast Forward. Published on April 3, 2012 as DOI: 10.1124/jpet.112.192096 at A PE T Jornals on July 9, 2017 jpet.asjournals.org D ow nladed from