Structure-Based Design of Highly Selective and Potent G Protein-Coupled Receptor Kinase 2 Inhibitors Based on Paroxetine

In heart failure, the β-adrenergic receptors (βARs) become desensitized and uncoupled from heterotrimeric G proteins. This process is initiated by G protein-coupled receptor kinases (GRKs), some of which are upregulated in the failing heart, making them desirable therapeutic targets. The selective serotonin reuptake inhibitor, paroxetine, was previously identified as a GRK2 inhibitor. Utilizing a structure-based drug design approach, we modified paroxetine to generate a small compound library. Included in this series is a highly potent and selective GRK2 inhibitor, 14as, with an IC₅₀ of 30 nM against GRK2 and greater than 230-fold selectivity over other GRKs and kinases. Furthermore, 14as showed a 100-fold improvement in cardiomyocyte contractility assays over paroxetine and a plasma concentration higher than its IC₅₀ for over 7 h. Three of these inhibitors, including 14as, were additionally crystallized in complex with GRK2 to give insights into the structural determinants of potency and selectivity of these inhibitors.