title: TAB4 stimulates TAK1-TAB1 phosphorylation and binds polyubiquitin to direct signaling to NF-kappaB.
abstract: Responses to transforming growth factor beta and multiple cytokines involve activation of transforming growth factor beta-activated kinase-1 (TAK1) kinase, which activates kinases IkappaB kinase (IKK) and MKK3/6, leading to the parallel activation of NF-kappaB and p38 MAPK. Activation of TAK1 by autophosphorylation is known to involve three different TAK1-binding proteins (TABs). Here we report a protein phosphatase subunit known as type 2A phosphatase-interacting protein (TIP) that also acts as a TAB because it co-precipitates with and directly binds to TAK1, enhances TAK1 autophosphorylation at unique sites, and promotes TAK1 phosphorylation of IKKbeta and signaling to NF-kappaB. Mass spectrometry demonstrated that co-expression of TAB4 protein significantly increased phosphorylation of four sites in TAK1, in a linker region between the kinase and TAB2/3 binding domains, and two sites in TAB1. Recombinant GST-TAB4 bound in an overlay assay directly to inactive TAK1 and activated TAK1 but not TAK1 phosphorylated in the linker sites, suggesting a bind and release mechanism. In kinase assays using TAK1 immune complexes, added GST-TAB4 selectively stimulated IKK phosphorylation. TAB4 co-precipitated polyubiquitinated proteins dependent on a Phe-Pro motif that was required to enhance phosphorylation of TAK1. TAB4 mutated at Phe-Pro dominantly interfered with IL-1beta activation of NF-kappaB involving IKK-dependent but not p38 MAPK-dependent signaling. The results show that TAB4 binds TAK1 and polyubiquitin chains to promote specific sites of phosphorylation in TAK1-TAB1, which activates IKK signaling to NF-kappaB.
authors.affiliation: Center for Cell Signaling and Department of Microbiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Todd D
authors.initials: TD
authors.lastname: Prickett
authors.forename: Jun
authors.initials: J
authors.lastname: Ninomiya-Tsuji
authors.forename: Peter
authors.initials: P
authors.lastname: Broglie
authors.forename: Tara L
authors.initials: TL
authors.lastname: Muratore-Schroeder
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Shabanowitz
authors.forename: Donald F
authors.initials: DF
authors.lastname: Hunt
authors.forename: David L
authors.initials: DL
authors.lastname: Brautigan
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs / Q000235:genetics; D019943:Amino Acid Substitution; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D048371:MAP Kinase Kinase 3 / Q000235:genetics / Q000378:metabolism; D048669:MAP Kinase Kinase 6 / Q000235:genetics / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D000099151:MAP Kinase Kinase Kinase 7
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051550:I-kappa B Kinase; D053583:Interleukin-1beta; D048371:MAP Kinase Kinase 3; D048669:MAP Kinase Kinase 6; D020930:MAP Kinase Kinase Kinases; D016328:NF-kappa B; D016212:Transforming Growth Factor beta; D025801:Ubiquitin; D048051:p38 Mitogen-Activated Protein Kinases; D000099151:MAP Kinase Kinase Kinase 7; C486300:TAB1 protein, human; C530937:TAB4 protein, human; C496560:IKBKB protein, human; C482530:MAP2K3 protein, human; C482566:MAP2K6 protein, human