The structures of salt-inducible kinase 3 in complex with inhibitors reveal determinants for binding and selectivity.

The salt-inducible kinases (SIKs) 1 to 3, belonging to the AMPK-related kinase family, serve as master regulators orchestrating a diverse set of physiological processes such as metabolism, bone formation, immune response, oncogenesis, and cardiac rhythm. Owing to its key regulatory role, the SIK kinases have emerged as compelling targets for pharmacological intervention across a diverse set of indications. Therefore, there is interest in developing SIK inhibitors with defined selectivity profiles both to further dissect the downstream biology and for treating disease. However, despite a large pharmaceutical interest in the SIKs, experimental structures of SIK kinases are scarce. This is likely due to the challenges associated with the generation of proteins suitable for structural studies. By adopting a rational approach to construct design and protein purification, we successfully crystallized and subsequently solved the structure of SIK3 in complex with HG-9-91-01, a potent SIK inhibitor. To enable further SIK3-inhibitor complex structures we identified an antibody fragment that facilitated crystallization and enabled a robust protocol suitable for structure-based drug design. The structures reveal SIK3 in an active conformation, where the ubiquitin-associated domain is shown to provide further stabilization to this active conformation. We present four pharmacologically relevant and distinct SIK3-inhibitor complexes. These detail the key interaction for each ligand and reveal how different regions of the ATP site are engaged by the different inhibitors to achieve high affinity. Notably, the structure of SIK3 in complex with a SIK3 specific inhibitor offers insights into isoform selectivity.

Design, synthesis, and biological evaluation of 3-benzenesulfonamide-linked 3-hydrazinoisatin derivatives as carbonic anhydrase inhibitors.

A new series of isatin-linked benzenesulfonamide derivatives (9a-w) were synthesized using the tail approach and assayed for their inhibitory potency against four different human carbonic anhydrase (hCA) isoforms, hCA I, II, IX, and XII. Most of these synthesized compounds exhibited interesting inhibition potency against isoforms hCA I, IX, and XII in the nanomolar range and by taking the standard drug acetazolamide. The most potent compounds in the case of hCA I were 9c (435.8 nM) and 9s (956.4 nM), for hCA IX, 9a (60.5 nM), 9d (95.6 nM), 9g (92.1 nM), and 9k (75.4 nM), and for hCA XII, 9p (84.5 nM). However, these compounds showed more selectivity toward hCA IX over hCA I, II, and XII. Thus, these compounds can be further developed as potential lead molecules for the development of isoform-selective hCA IX inhibitors with further structural modifications.

Quantitative Characterization of the Chemical Space Governed by Human Carbonic Anhydrases and selenium-containing derivatives of solfonamides

Abstract Due to the fact that different isoforms of carbonic anhydrase play distinct physiological roles, their diseases/disorders involvement are different as well. Involvement in major disorders such as glaucoma, epilepsy, Alzheimer's disease, obesity and cancers, have turned carbonic anhydrase into a popular case study in the field of rational drug design. Since carbonic anhydrases are highly similar with regard to their structures, selective inhibition of different isoforms has been a significant challenge. By applying a proteochemometrics approach, herein the chemical interaction space governed by acyl selenoureido benzensulfonamides and human carbonic anhydrases is explored. To assess the validity, robustness and predictivity power of the proteochemometrics model, a diverse set of validation methods was used. The final model is shown to provide valuable structural information that can be considered for new selective inhibitors design. Using the supplied information and to show the applicability of the constructed model, new compounds were designed. Monitoring of selectivity ratios of new designs shows very promising results with regard to their selectivity for a specific isoform of carbonic anhydrase.