title: The kinase activity of Rip1 is not required for tumor necrosis factor-alpha-induced IkappaB kinase or p38 MAP kinase activation or for the ubiquitination of Rip1 by Traf2.
abstract: The death domain kinase Rip1 is recruited to the tumor necrosis factor receptor type 1 and mediates the IkappaB kinase and p38 MAP kinase pathways. In response to tumor necrosis factor-alpha (TNF-alpha), we find Rip1 phosphorylated and ubiquitinated, suggesting that Rip1 phosphorylation may stimulate its ubiquitination. To address the contribution of the kinase activity of Rip1 to its ubiquitination and to TNF-alpha signaling, we introduced wild type Rip1 and a kinase-inactive form of Rip1, Rip1D138N, into rip1-/- murine embryonic fibroblast cells by retroviral infection. TNF-alpha-induced ubiquitination of Rip1 is observed in Rip1D138N cells, supporting the argument that Rip1 autophosphorylation is not required for Rip1 ubiquitination. TNF-alpha-induced Ikk and p38 MAP kinase activation is normal, and the Rip1D138N cells are resistant to TNF-alpha-induced cell death, indicating that the kinase activity of Rip1 is not required to mediate its antiapoptotic functions. In the absence of Traf2, TNF-alpha-induced ubiquitination of Rip1 is impaired, suggesting that Traf2 may be the E3 ubiquitin ligase responsible for the TNF-alpha-dependent, ubiquitination of Rip1. Finally, recruitment of the ubiquitinated Tak1 complex is dependent on the presence of Rip1, suggesting that Rip1 ubiquitination rather than its phosphorylation is critical in signaling.
authors.affiliation: Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Lee
authors.forename: Jennifer
authors.initials: J
authors.lastname: Shank
authors.forename: Nicole
authors.initials: N
authors.lastname: Cusson
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Kelliher
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D004622:Embryo, Mammalian; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts; D020690:GTPase-Activating Proteins / Q000172:deficiency / Q000502:physiology*; D051550:I-kappa B Kinase; D015850:Interleukin-6 / Q000096:biosynthesis; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I; D047992:TNF Receptor-Associated Factor 2; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D025801:Ubiquitin / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases; D000099151:MAP Kinase Kinase Kinase 7
chemical_list: D015703:Antigens, CD; D020690:GTPase-Activating Proteins; D051550:I-kappa B Kinase; D015850:Interleukin-6; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047992:TNF Receptor-Associated Factor 2; D014409:Tumor Necrosis Factor-alpha; D025801:Ubiquitin; D048051:p38 Mitogen-Activated Protein Kinases; D000099151:MAP Kinase Kinase Kinase 7; C490620:Ralbp1 protein, mouse; C496564:Chuk protein, mouse; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse