Interplay between BCL10, MALT1 and IkappaBalpha during T-cell-receptor-mediated NFkappaB activation.
T-cell-receptor (TCR) signalling to NFkappaB requires the assembly of a large multiprotein complex containing the serine/threonine kinase CK1alpha, the scaffold protein CARMA1, the heterodimer BCL10-MALT1 (the CBM complex) and the IkappaB kinase complex (IKK). Although the mechanisms regulating recruitment and activation of IKK within the CBM microenvironment have been extensively studied, there is little understanding of how IKK subsequently binds and phosphorylates IkappaBalpha, the inhibitor of NFkappaB, to promote IkappaBalpha ubiquitylation and proteasomal degradation. Here, we show that BCL10, MALT1 and IKK inducibly associate with IkappaBalpha in a complex that is physically distinct from the early CK1alpha-CBM signalosome. This IkappaBalpha-containing complex probably maturates from the CBM, because siRNA-based knockdown of CARMA1, CK1alpha and BCL10 hampered its assembly, leading to a reduction in NFkappaB activation. By contrast, CK1alpha normally recruited both BCL10 and ubiquitylated species of MALT1 when IkappaBalpha levels were reduced. However, knockdown of IkappaBalpha led to an altered ubiquitylation profile of BCL10-MALT1 combined with a defect in MALT1 reorganisation within large cytoplasmic structures, suggesting that, following stimulation, IkappaBalpha might also participate in MALT1 recycling. Altogether, our data suggest a two-step mechanism to connect active IKK to IkappaBalpha, and further unveil a potential role for IkappaBalpha in resetting TCR-mediated signalling.
Carvalho
Gabrielle
G
INSERM UMR_S 1014, Hôpital Paul Brousse, Villejuif 94800, France.
Le Guelte
Armelle
A
Demian
Catherine
C
Vazquez
Aimé
A
Gavard
Julie
J
Bidère
Nicolas
N
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000074018:B-Cell CLL-Lymphoma 10 Protein; D053468:CARD Signaling Adaptor Proteins / Q000235:genetics / Q000378:metabolism; D048128:Casein Kinase Ialpha / Q000235:genetics / Q000378:metabolism; D020169:Caspases / Q000235:genetics / Q000378:metabolism*; D006162:Guanylate Cyclase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism*; D019169:Jurkat Cells; D021962:Membrane Microdomains / Q000378:metabolism; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; D046912:Multiprotein Complexes / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization / Q000235:genetics; D021381:Protein Transport / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D015533:Transcriptional Activation / Q000235:genetics; D054875:Ubiquitination / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D000074018:B-Cell CLL-Lymphoma 10 Protein; C118591:BCL10 protein, human; D053468:CARD Signaling Adaptor Proteins; D020672:I-kappa B Proteins; D046912:Multiprotein Complexes; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; D011948:Receptors, Antigen, T-Cell; D000072000:NF-KappaB Inhibitor alpha; D048128:Casein Kinase Ialpha; D020169:Caspases; C400109:MALT1 protein, human; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; C426242:CARD11 protein, human; D006162:Guanylate Cyclase