MAGUK-controlled ubiquitination of CARMA1 modulates lymphocyte NF-kappaB activity.
The adaptor protein CARMA1 is required for antigen receptor-triggered activation of IKK and JNK in lymphocytes. Once activated, the events that subsequently turn off the CARMA1 signalosome are unknown. In this study, we found that antigen receptor-activated CARMA1 underwent lysine 48 (K48) polyubiquitination and proteasome-dependent degradation. The MAGUK region of CARMA1 was an essential player in this event; the SH3 and GUK domains contained the main ubiquitin acceptor sites, and deletion of a Hook domain (an important structure for maintaining inactive MAGUK proteins) between SH3 and GUK was sufficient to induce constitutive ubiquitination of CARMA1. A similar deletion promoted the ubiquitination of PSD-95 and Dlgh1, suggesting that a conserved mechanism may control the turnover of other MAGUK family protein complexes. Functionally, we demonstrated that elimination of MAGUK ubiquitination sites in CARMA1 resulted in elevated basal and inducible NF-kappaB and JNK activation as a result of defective K48 ubiquitination and increased persistence of this ubiquitination-deficient CARMA1 protein in activated lymphocytes. The coordination of degradation with the full activation of the CARMA1 molecule likely provides an intrinsic feedback control mechanism to balance lymphocyte activation upon antigenic stimulation.
Moreno-García
Miguel E
ME
Center for Immunity and Immunotherapies, Seattle Children's Research Institute, 1900 Ninth Avenue, Seattle, WA 98101, USA.
Sommer
Karen
K
Shinohara
Hisaaki
H
Bandaranayake
Ashok D
AD
Kurosaki
Tomohiro
T
Rawlings
David J
DJ
D000595:Amino Acid Sequence; D000818:Animals; D030161:Avian Proteins / Q000172:deficiency / Q000378:metabolism*; D053468:CARD Signaling Adaptor Proteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002645:Chickens; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D011493:Protein Kinase C / Q000172:deficiency / Q000378:metabolism; D064546:Protein Kinase C beta; D016415:Sequence Alignment; D054875:Ubiquitination
D030161:Avian Proteins; D053468:CARD Signaling Adaptor Proteins; C496467:Card11 protein, mouse; D016328:NF-kappa B; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D046988:Proteasome Endopeptidase Complex