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Structure‐Based Design of IKKɛ and TBK1 Inhibitors for the Treatment of Obesity
Author(s) -
Beyett Tyler S,
Labudde Emily,
Tesmer John J. G.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.817.4
Subject(s) - iκb kinase , kinase , docking (animal) , pharmacology , materials science , biochemistry , medicine , chemistry , nf κb , signal transduction , nursing
Obesity is a leading factor in the development of type 2 diabetes. It has been shown that inhibitor of NF‐κB kinase epsilon (IKKɛ) and TANK‐binding kinase 1 (TBK1) are upregulated in adipocytes of obese individuals. Knockdown of either kinase results in significant weight loss and increased insulin sensitivity. High‐throughput screening identified the FDA‐approved drug amlexanox as an ATP‐competitive inhibitor of both kinases which produces significant weight loss when administered to obese mice. Amlexanox has poor solubility and metabolic profile when administered orally, necessitating the design of improved analogs for clinical use. Docking simulations have not provided consistent binding modes for amlexanox due to the planar and somewhat symmetrical structure of the molecule, limiting rational design of improved analogs. To better understand the molecular mechanism of inhibition and to guide further development, we sought to obtain co‐crystals structures of IKKɛ and TBK1 with amlexanox and related analogs. While crystallization of IKKɛ has been unsuccessful, we generated two crystal forms of TBK1 in complex with the potent inhibitor MRT67307 but were unable to obtain co‐crystals in the presence of amlexanox. Soaking these crystals in amlexanox resulted in a significant decrease in diffraction quality and partial density for the original inhibitor. TBK1·amlexanox crystals of a moderate resolution (3.7 Å) were obtained via microseeding and subsequent macroseeding. The resulting structure shows amlexanox binding along the hinge of the kinase and suggests that the carboxylate on amlexanox may form a salt bridge with Lys38 and/or Thr156. Differential scanning fluorometry with an K38A mutant shows a loss in thermal stabilization by amlexanox, and analogs with modifications to the carboxylate display decreased or abolished ability to inhibit TBK1. Knowledge of the potential importance of the carboxylate‐Lys38 interaction will guide the development of future amlexanox analogs. Presently, we have developed amlexanox analogs with improved efficacy in mouse models and are progressing them towards the clinic. Support or Funding Information National Institutes of Health, Pharmacological Sciences Training Program (T32‐GM007767), Rackham Graduate School at the University of Michigan