A novel allosteric inhibitor that prevents IKK? activation.

ABSTRACT: I kappa B kinase ? (IKK?) is one of the primary targets to regulate canonical NF-?B activity. The misregulation of NF-?B is associated with various diseases, including chronic inflammation and cancers. Most of the known IKK? inhibitors target its active form and suffer from poor selectivity. In the present study, we aim to design inhibitors that can bind to the IKK? inactive form and block its activation. We identified a potential allosteric site between the kinase domain (KD) and ubiquitin-like domain (ULD) of human IKK? and used it to virtually screen a chemical library for allosteric inhibitors. Among the 133 compounds tested, 16 inhibited NF-?B activity by over 50% at 50 ?M in a reporter gene assay. Further quantitative measurements and cytotoxicity study gave one compound 124 (3,4-dichloro-2-ethoxy-N-(2,2,6,6-tetramethylpiperidin-4-yl)benzenesulfonamide) which specifically targets the IKK? inactive form. In cells, 124 inhibited I?B? phosphorylation and NF-?B transcriptional activity for the reporter gene with an IC50 of 35 ?M by decreasing the phosphorylation level of Ser177/181 on IKK? and blocking its activation upon TNF? stimulation. Molecular dynamics simulations demonstrated that 124 binds to the pocket between KD and ULD in the inactive conformation of IKK? rather than the active conformation. As the first allosteric inhibitor that prevents IKK? activation, 124 provides a good starting point for further inhibitor discovery and a probe for IKK? enzyme cycle and regulatory mechanism study.

SUBMITTER: Liu H 

PROVIDER: S-EPMC6083782 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature