Development of Pyridine-Based Inhibitors for the Human Vaccinia-Related Kinases 1 and 2

Vaccinia-related kinases 1 and 2 (VRK1 and VRK2) are human Ser/Thr protein kinases associated with increased cell division and neurological disorders. Nevertheless, the cellular functions of these proteins are not fully understood. Despite their therapeutic potential, there are no inhibitors available for VRK1 or VRK2. We report here the discovery and elaboration of an aminopyridine scaffold as a basis for VRK1 and VRK2 inhibitors. The most potent compounds displayed K_D values of 190 nM and 401 nM for VRK1 and VRK2, respectively. Differences in compound binding mode and substituent preferences between the two VRKs were identified by the series structure-activity relationship combined with the crystallographic analysis of key compounds. We expect that our results will serve as a starting point for the design of specific and potent inhibitors against each of the two VRKs based on a pyridine scaffold.