Discovery and Optimization of 5-Hydroxy-Diclofenac toward a New Class of Ligands with Nanomolar Affinity for the CaMKIIα Hub Domain
Yongsong Tian, Mohamed A. Shehata, Stine Juul Gauger, Clarissa K. L. Ng, Sara M. Ø. Solbak, Louise Thiesen, Jesper Bruus‐Jensen, Jacob Krall, Christoffer Bundgaard, K. Michael Gibson, Petrine Wellendorph, Bente Frølund
Abstract
The Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα) is a brain-relevant kinase involved in long-term potentiation and synaptic plasticity. We have recently pinpointed the CaMKIIα hub domain as the long-sought-after high-affinity target of γ-hydroxybutyrate ligands substantiated with a high-resolution cocrystal of 5-hydroxydiclofenac (3). Herein, we employed in silico approaches to rationalize and guide the synthesis and pharmacological characterization of a new series of analogues circumventing chemical stability problems associated with 3. The oxygen-bridged analogue 4d showed mid-nanomolar affinity and notable ligand-induced stabilization effects toward the CaMKIIα hub oligomer. Importantly, 4d displayed superior chemical and metabolic stability over 3 by showing excellent chemical stability in phosphate-buffered saline and high resistance to form reactive intermediates and subsequent sulfur conjugates. Altogether, our study highlights 4d as a new CaMKIIα hub high-affinity ligand with enhanced pharmacokinetic properties, representing a powerful tool compound for allosteric regulation of kinase activity with subtype specificity.