title: Ubiquitination and translocation of TRAF2 is required for activation of JNK but not of p38 or NF-kappaB.
abstract: TRAF2 is a RING finger protein that regulates the cellular response to stress and cytokines by controlling JNK, p38 and NF-kappaB signaling cascades. Here, we demonstrate that TRAF2 ubiquitination is required for TNFalpha-induced activation of JNK but not of p38 or NF-kappaB. Intact RING and zinc finger domains are required for TNFalpha-induced TRAF2 ubiquitination, which is also dependent on Ubc13. TRAF2 ubiquitination coincides with its translocation to the insoluble cellular fraction, resulting in selective activation of JNK. Inhibition of Ubc13 expression by RNAi resulted in inhibition of TNFalpha-induced TRAF2 translocation and impaired activation of JNK but not of IKK or p38. TRAF2 aggregates in the cytoplasm, as seen in Hodgkin-Reed-Sternberg lymphoma cells, resulting in constitutive NF-kappaB activity but failure to activate JNK. These findings demonstrate that the TRAF2 RING is required for Ubc13-dependent ubiquitination, resulting in translocation of TRAF2 to an insoluble fraction and activation of JNK, but not of p38 or NF-kappaB. Altogether, our findings highlight a novel mechanism of TRAF2-dependent activation of diverse signaling cascades that is impaired in Hodgkin-Reed-Sternberg cells.
authors.affiliation: Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY, USA.
authors.forename: Hasem
authors.initials: H
authors.lastname: Habelhah
authors.forename: Shoichi
authors.initials: S
authors.lastname: Takahashi
authors.forename: Ssang-Goo
authors.initials: SG
authors.lastname: Cho
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kadoya
authors.forename: Toshiki
authors.initials: T
authors.lastname: Watanabe
authors.forename: Ze'ev
authors.initials: Z
authors.lastname: Ronai
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003505:Cyclodextrins / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D021962:Membrane Microdomains / Q000187:drug effects; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D034622:RNA Interference; D016539:Reed-Sternberg Cells; D047992:TNF Receptor-Associated Factor 2; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D044763:Ubiquitin-Conjugating Enzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D014452:Ubiquitins / Q000378:metabolism*; D047392:beta-Cyclodextrins; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D003505:Cyclodextrins; D020672:I-kappa B Proteins; D016328:NF-kappa B; D011506:Proteins; D047992:TNF Receptor-Associated Factor 2; D014409:Tumor Necrosis Factor-alpha; D014452:Ubiquitins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C471607:UBE2N protein, human; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases