title: Malt1 ubiquitination triggers NF-kappaB signaling upon T-cell activation.
abstract: Triggering of antigen receptors on lymphocytes is critical for initiating adaptive immune response against pathogens. T-cell receptor (TCR) engagement induces the formation of the Carma1-Bcl10-Malt1 (CBM) complex that is essential for activation of the IkappaB kinase (IKK)/NF-kappaB pathway. However, the molecular mechanisms that link CBM complex formation to IKK activation remain unclear. Here we report that Malt1 is polyubiquitinated upon T-cell activation. Ubiquitin chains on Malt1 provide a docking surface for the recruitment of the IKK regulatory subunit NEMO/IKKgamma. TRAF6 associates with Malt1 in response to T-cell activation and can function as an E3 ligase for Malt1 in vitro and in vivo, mediating lysine 63-linked ubiquitination of Malt1. Multiple lysine residues in the C-terminus of Malt1 serve as acceptor sites for the assembly of polyubiquitin chains. Malt1 mutants that lack C-terminal ubiquitin acceptor lysines are impaired in rescuing NF-kappaB signaling and IL-2 production in Malt1-/- T cells. Thus, our data demonstrate that induced Malt1 ubiquitination is critical for the engagement of CBM and IKK complexes, thereby directing TCR signals to the canonical NF-kappaB pathway.
authors.affiliation: GSF-National Research Center for Environment and Health, Institute of Toxicology, Neuherberg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Oeckinghaus
authors.forename: Elmar
authors.initials: E
authors.lastname: Wegener
authors.forename: Verena
authors.initials: V
authors.lastname: Welteke
authors.forename: Uta
authors.initials: U
authors.lastname: Ferch
authors.forename: Seda Cöl
authors.initials: SC
authors.lastname: Arslan
authors.forename: Jürgen
authors.initials: J
authors.lastname: Ruland
authors.forename: Claus
authors.initials: C
authors.lastname: Scheidereit
authors.forename: Daniel
authors.initials: D
authors.lastname: Krappmann
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000074018:B-Cell CLL-Lymphoma 10 Protein; D053468:CARD Signaling Adaptor Proteins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D006162:Guanylate Cyclase / Q000378:metabolism; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D019169:Jurkat Cells; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; D016328:NF-kappa B / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D000074018:B-Cell CLL-Lymphoma 10 Protein; C118591:BCL10 protein, human; D053468:CARD Signaling Adaptor Proteins; D007376:Interleukin-2; D016328:NF-kappa B; D009363:Neoplasm Proteins; D048029:TNF Receptor-Associated Factor 6; D051550:I-kappa B Kinase; D020169:Caspases; C400109:MALT1 protein, human; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; C426242:CARD11 protein, human; D006162:Guanylate Cyclase