CKIP-1 is an intrinsic negative regulator of T-cell activation through an interaction with CARMA1

• Published in: PloS one 2014-01, Vol.9 (1), p.e85762
• Main Authors: Sakamoto, Takashi, Kobayashi, Masayuki, Tada, Kohei, Shinohara, Masanobu, Io, Katsuhiro, Nagata, Kayoko, Iwai, Fumie, Takiuchi, Yoko, Arai, Yasuyuki, Yamashita, Kouhei, Shindo, Keisuke, Kadowaki, Norimitsu, Koyanagi, Yoshio, Takaori-Kondo, Akifumi
• Format: Article
• Language: English
• Subjects: Activation; Antigens; Bcl-10 protein; Biology; CARD Signaling Adaptor Proteins - metabolism; Carrier Proteins - chemistry; Carrier Proteins - metabolism; Casein; CD28 antigen; CD3 antigen; Cell activation; Cloning; Complementation; Dissociation; Down-regulation; Enzyme Activation - drug effects; Guanylate Cyclase - metabolism; Hematology; Humans; Immune response; Immune system; Immunology; Intracellular Signaling Peptides and Proteins; Isoenzymes - metabolism; Jurkat Cells; Kinases; Lipid rafts; Lipids; Localization; Lymphocyte Activation - drug effects; Lymphocyte Activation - immunology; Lymphocytes; Lymphocytes T; Lymphoma; Lymphomas; Medicine; Membrane Microdomains - drug effects; Membrane Microdomains - metabolism; Mutagenesis; Mutation; NF-kappa B - metabolism; NF-κB protein; Oncology; Phosphorylation; Protein Binding - drug effects; Protein kinase C; Protein Kinase C - metabolism; Protein Kinase C-theta; Protein Structure, Tertiary; Proteins; Rafts; Regulators; Signaling; Stimulation; T cell receptors; T cells; T-cell receptor; T-Lymphocytes - drug effects; T-Lymphocytes - enzymology; T-Lymphocytes - immunology; Tetradecanoylphorbol Acetate - pharmacology; Tumor necrosis factor-α
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0085762

The transcription factor NF-κB plays a key regulatory role in lymphocyte activation and generation of immune response. Stimulation of T cell receptor (TCR) induces phosphorylation of CARMA1 by PKCθ, resulting in formation of CARMA1-Bcl10-MALT1 (CBM) complex at lipid rafts and subsequently leading to NF-κB activation. While many molecular events leading to NF-κB activation have been reported, it is less understood how this activation is negatively regulated. We performed a cell-based screening for negative regulators of TCR-mediated NF-κB activation, using mutagenesis and complementation cloning strategies. Here we show that casein kinase-2 interacting protein-1 (CKIP-1) suppresses PKCθ-CBM-NF-κB signaling. We found that CKIP-1 interacts with CARMA1 and competes with PKCθ for association. We further confirmed that a PH domain of CKIP-1 is required for association with CARMA1 and its inhibitory effect. CKIP-1 represses NF-κB activity in unstimulated cells, and inhibits NF-κB activation induced by stimulation with PMA or constitutively active PKCθ, but not by stimulation with TNFα. Interestingly, CKIP-1 does not inhibit NF-κB activation induced by CD3/CD28 costimulation, which caused dissociation of CKIP-1 from lipid rafts. These data suggest that CKIP-1 contributes maintenance of a resting state on NF-κB activity or prevents T cells from being activated by inadequate signaling. In conclusion, we demonstrate that CKIP-1 interacts with CARMA1 and has an inhibitory effect on PKCθ-CBM-NF-κB signaling.