title: The Ca2+-dependent phosphatase calcineurin controls the formation of the Carma1-Bcl10-Malt1 complex during T cell receptor-induced NF-kappaB activation.
abstract: T cell receptor (TCR) ligation induces increased diacylglycerol and Ca(2+) levels in T cells, and both secondary messengers are crucial for TCR-induced nuclear factor of activated T cells (NF-AT) and NF-κB signaling pathways. One prominent calcium-dependent enzyme involved in the regulation of NF-AT and NF-κB signaling pathways is the protein phosphatase calcineurin. However, in contrast to NF-AT, which is directly dephosphorylated by calcineurin, the molecular basis of the calcium-calcineurin dependence of the TCR-induced NF-κB activity remains largely unknown. Here, we demonstrate that calcineurin regulates TCR-induced NF-κB activity by controlling the formation of a protein complex composed of Carma1, Bcl10, and Malt1 (CBM complex). For instance, increased calcium levels induced by ionomycin or thapsigargin augmented the phorbol 12-myristate 13-acetate-induced formation of the CBM complex and activation of NF-κB, whereas removal of calcium by the calcium chelator EGTA-acetoxymethyl ester (AM) attenuated both processes. Furthermore, inhibition of the calcium-dependent phosphatase calcineurin with the immunosuppressive agent cyclosporin A (CsA) or FK506 as well as siRNA-mediated knockdown of calcineurin A strongly affected the PMA + ionomycin- or anti-CD3 + CD28-induced CBM complex assembly. Mechanistically, the positive effect of calcineurin on the CBM complex formation seems to be linked to a dephosphorylation of Bcl10. For instance, Bcl10 was found to be hyperphosphorylated in Jurkat T cells upon treatment with CsA or EGTA-AM, and calcineurin dephosphorylated Bcl10 in vivo and in vitro. Furthermore, we show here that calcineurin A interacts with the CBM complex. In summary, the evidence provided here argues for a previously unanticipated role of calcineurin in CBM complex formation as a molecular basis of the inhibitory function of CsA or FK506 on TCR-induced NF-κB activity.
authors.affiliation: Institute of Physiological Chemistry, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
authors.forename: Lysann
authors.initials: L
authors.lastname: Palkowitsch
authors.forename: Uta
authors.initials: U
authors.lastname: Marienfeld
authors.forename: Cornelia
authors.initials: C
authors.lastname: Brunner
authors.forename: Andrea
authors.initials: A
authors.lastname: Eitelhuber
authors.forename: Daniel
authors.initials: D
authors.lastname: Krappmann
authors.forename: Ralf B
authors.initials: RB
authors.lastname: Marienfeld
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D000074018:B-Cell CLL-Lymphoma 10 Protein; D053468:CARD Signaling Adaptor Proteins / Q000276:immunology / Q000378:metabolism*; D019703:Calcineurin / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D020169:Caspases / Q000276:immunology / Q000378:metabolism*; D016572:Cyclosporine / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000276:immunology / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D019169:Jurkat Cells; D051379:Mice; D008815:Mice, Inbred Strains; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation / Q000276:immunology; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016559:Tacrolimus / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000074018:B-Cell CLL-Lymphoma 10 Protein; C118591:BCL10 protein, human; D053468:CARD Signaling Adaptor Proteins; D007166:Immunosuppressive Agents; D016328:NF-kappa B; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; D004533:Egtazic Acid; D016572:Cyclosporine; C046770:EGTA acetoxymethyl ester; D019703:Calcineurin; D020169:Caspases; C400109:MALT1 protein, human; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; C426242:CARD11 protein, human; D006162:Guanylate Cyclase; D002118:Calcium; D016559:Tacrolimus