title: Withaferin A inhibits NF-kappaB activation by targeting cysteine 179 in IKKβ.
abstract: The transcription factor NF-κB is one of the main players involved in inflammatory responses during which NF-κB becomes rapidly activated. However to maintain homeostasis, this NF-κB activation profile is only transient. Nevertheless deregulation of NF-κB activity is often observed and can lead to chronic inflammatory diseases as well as cancer. Therefore various research projects focus on the development of therapeutics that target the NF-κB activation pathway. One such compound is Withaferin A from the Ayurvedic plant Withania somnifera. Several reports already described the NF-κB inhibiting, anti-inflammatory capacity of WA, either in vitro as well as in vivo. However the underlying molecular mechanism remains largely unknown. In this paper we demonstrate a direct interaction of WA with the IKK-complex, more specifically with IKKβ, a kinase which is indispensable for the nuclear translocation of NF-κB. Hereby WA directly inhibits IKK catalytic activity. By mutation of Cys179 in IKKβ we could demonstrate loss of interaction between IKKβ and WA indicating that WA exerts its anti-inflammatory effects by targeting the crucial Cys179 residue located in the catalytic site of IKKβ. Upon docking of WA to a IKKβ homology structure model, WA was found to fit nicely into the groove of IKKβ where it can form hydrogen bond to stabilize its interaction with Cys179.
authors.affiliation: Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Physiology, Ghent University, Proeftuinstraat 86, Gent, Belgium. Electronic address: karen.heyninck@ugent.be.
authors.forename: Karen
authors.initials: K
authors.lastname: Heyninck
authors.affiliation: School of Pharmacy, Pharmaceutical Chemistry, University of Eastern Finland, 70211 Kuopio, Finland.
authors.forename: Maija
authors.initials: M
authors.lastname: Lahtela-Kakkonen
authors.affiliation: Laboratory for Medicinal Chemistry, Department of Pharmaceutical Sciences, University Antwerp, Campus Drie Eiken, Universiteitsplein 1, Wilrijk, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Van der Veken
authors.affiliation: Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Physiology, Ghent University, Proeftuinstraat 86, Gent, Belgium.
authors.forename: Guy
authors.initials: G
authors.lastname: Haegeman
authors.affiliation: Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Physiology, Ghent University, Proeftuinstraat 86, Gent, Belgium; Laboratory of Protein Science, Proteomics and Epigenetic Signaling (PPES), Department of Biomedical Sciences, University Antwerp, Campus Drie Eiken, Universiteitsplein 1, Wilrijk, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Vanden Berghe
mesh_terms: D020134:Catalytic Domain; D002853:Chromatography, Liquid; D003545:Cysteine / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000737:chemistry / Q000378:metabolism*; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054358:Withanolides / Q000494:pharmacology*
chemical_list: D016328:NF-kappa B; D054358:Withanolides; D051550:I-kappa B Kinase; D003545:Cysteine; C009684:withaferin A
keywords: Cysteine; Inflammation; Kinase; Natural product; Signal transduction