title: Tyrosine phosphorylation allows integration of multiple signaling inputs by IKKβ.
abstract: Signaling regulated by NFκB and related transcription factors is centrally important to many inflammatory and autoimmune diseases, cancer, and stress responses. The kinase that directly regulates the canonical NFκB transcriptional pathway, Inhibitor of κB kinase β (IKKβ), undergoes activation by Ser phosphorylation mediated by NIK or TAK1 in response to inflammatory signals. Using titanium dioxide-based phosphopeptide enrichment (TiO2)-liquid chromatography (LC)-high mass accuracy tandem mass spectrometry (MS/MS), we analyzed IKKβ phosphorylation in human HEK293 cells expressing IKKβ and FGFR2, a Receptor tyrosine kinase (RTK) essential for embryonic differentiation and dysregulated in several cancers. We attained unusually high coverage of IKKβ, identifying an abundant site of Tyr phosphorylation at Tyr169 within the Activation Loop. The phosphomimic at this site confers a level of kinase activation and NFκB nuclear localization exceeding the iconic mutant S177E/S181E, demonstrating that RTK-mediated Tyr phosphorylation of IKKβ has the potential to directly regulate NFκB transcriptional activation.
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America.
authors.forename: April N
authors.initials: AN
authors.lastname: Meyer
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Kristine A
authors.initials: KA
authors.lastname: Drafahl
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: McAndrew
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Gilda
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Leandro H
authors.initials: LH
authors.lastname: Gallo
authors.affiliation: Moores UCSD Cancer Center, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Martin
authors.initials: M
authors.lastname: Haas
authors.affiliation: Sanford-Burnham Medical Research Institute, La Jolla, California, United States of America.
authors.forename: Laurence M
authors.initials: LM
authors.lastname: Brill
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America ; Moores UCSD Cancer Center, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Donoghue
mesh_terms: D019943:Amino Acid Substitution; D004789:Enzyme Activation / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D017433:Protein Structure, Secondary; D051497:Receptor, Fibroblast Growth Factor, Type 2 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism
chemical_list: D016328:NF-kappa B; D014443:Tyrosine; C496353:FGFR2 protein, human; D051497:Receptor, Fibroblast Growth Factor, Type 2; D051550:I-kappa B Kinase; C496560:IKBKB protein, human