title: Withaferin a strongly elicits IkappaB kinase beta hyperphosphorylation concomitant with potent inhibition of its kinase activity.
abstract: The transcription factor NFkappaB plays a critical role in normal and pathophysiological immune responses. Therefore, NFkappaB and the signaling pathways that regulate its activation have become a major focus of drug development programs. Withania somnifera (WS) is a medicinal plant that is widely used in Palestine for the treatment of various inflammatory disorders. In this study we show that the leave extract of WS, as well as its major constituent withaferin A (WA), potently inhibits NFkappaB activation by preventing the tumor necrosis factor-induced activation of IkappaB kinase beta via a thioalkylation-sensitive redox mechanism, whereas other WS-derived steroidal lactones, such as withanolide A and 12-deoxywithastramonolide, are far less effective. To our knowledge, this is the first communication of IkappaB kinase beta inhibition by a plant-derived inhibitor, coinciding with MEK1/ERK-dependent Ser-181 hyperphosphorylation. This prevents IkappaB phosphorylation and degradation, which subsequently blocks NFkappaB translocation, NFkappaB/DNA binding, and gene transcription. Taken together, our results indicate that pure WA or WA-enriched WS extracts can be considered as a novel class of NFkappaB inhibitors, which hold promise as novel anti-inflammatory agents for treatment of various inflammatory disorders and/or cancer.
authors.affiliation: Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Molecular Biology, Ghent University-UGent, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium; Master program in Clinical Laboratory Sciences, Birzeit University, P. O. Box 14, Birzeit, Palestine.
authors.forename: Mary
authors.initials: M
authors.lastname: Kaileh
authors.affiliation: Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Molecular Biology, Ghent University-UGent, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Vanden Berghe
authors.affiliation: Laboratory of Pharmacognosy and Phytochemistry, Ghent University-UGent, Harelbekestraat 72, B-9000 Gent, Belgium.
authors.forename: Arne
authors.initials: A
authors.lastname: Heyerick
authors.affiliation: Center for Biomedical Integrated Genoproteomics (CBIG), Virology and Immunology Unit, Institute of Pathology B23, B-4000 Liege, Belgium.
authors.forename: Julie
authors.initials: J
authors.lastname: Horion
authors.affiliation: Center for Biomedical Integrated Genoproteomics (CBIG), Virology and Immunology Unit, Institute of Pathology B23, B-4000 Liege, Belgium.
authors.forename: Jacques
authors.initials: J
authors.lastname: Piette
authors.affiliation: Department of Molecular Biomedical Research, Flanders Interuniversity for Biotechnology and Ghent University, Technologiepark 927, B-9052 Zwijnaarde, Belgium, and.
authors.forename: Claude
authors.initials: C
authors.lastname: Libert
authors.affiliation: Laboratory of Pharmacognosy and Phytochemistry, Ghent University-UGent, Harelbekestraat 72, B-9000 Gent, Belgium.
authors.forename: Denis
authors.initials: D
authors.lastname: De Keukeleire
authors.affiliation: Master program in Clinical Laboratory Sciences, Birzeit University, P. O. Box 14, Birzeit, Palestine.
authors.forename: Tamer
authors.initials: T
authors.lastname: Essawi
authors.affiliation: Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Molecular Biology, Ghent University-UGent, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium. Electronic address: Guy.Haegeman@UGent.be.
authors.forename: Guy
authors.initials: G
authors.lastname: Haegeman
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000302:isolation & purification; D045744:Cell Line, Tumor; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D006801:Humans; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007249:Inflammation / Q000188:drug therapy / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D032341:Withania / Q000737:chemistry; D054358:Withanolides
chemical_list: C433551:3-rhamnopyranosyl(1-4)-glucopyranosyl-12-diacetoxy-20-hydroxywitha-5,24-dienolide; D000893:Anti-Inflammatory Agents; D016328:NF-kappa B; D010936:Plant Extracts; D047428:Protein Kinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; D054358:Withanolides; D051550:I-kappa B Kinase; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; C009684:withaferin A; D004875:Ergosterol