Protein kinase C-δ negatively regulates T cell receptor-induced NF-κB activation by inhibiting the assembly of CARMA1 signalosome

Yu Liu, Ren Song, Yan Gao, Yi Li, Shuai Wang, Hai Yun Liu, Yan Wang, Yun Hong Hu, Hong Bing Shu

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


T-cell receptor (TCR)-induced T-cell activation is a critical event in adaptive immune responses. The engagement of TCR complex by antigen along with the activation of the costimulatory receptors trigger a cascade of intracellular signaling, in which caspase recruitment domain-containing membrane-associated guanylate kinase 1 (CARMA1) is a crucial scaffold protein. Upon stimulation, CARMA1 recruits downstream molecules including B-cell CLL/lymphoma 10 (Bcl10), mucosa-associated lymphoid tissue lymphoma translocation gene 1 (MALT1), and TRAF6 to assemble a specific TCR-induced signalosome that triggers NF-κB and JNK activation. In this report, we identified protein kinase Cδ (PKCδ) as a CARMA1-associated protein by a biochemical affinity purification approach. PKCδ interacted with CARMA1 in TCR stimulation-dependent manner in Jurkat T cells. Overexpression of PKCδ inhibited CARMA1-mediated NF-κB activation, whereas knockdown of PKCδ potentiated TCR-triggered NF-κB activation and IL-2 secretion in Jurkat T cells. Reconstitution experiments with PKCδ kinase-dead mutant indicated that the kinase activity of PKCδ was dispensable for its ability to inhibit TCR-triggered NF-κB activation. Furthermore, we found that PKCδ inhibited the interaction between MALT1 and TRAF6, but not the association of CARMA1 with PKCθ, Bcl10, or MALT1. These observations suggest that PKCδ is a negative regulator in T cell activation through inhibiting the assembly of CARMA1 signalosome.

Original languageEnglish (US)
Pages (from-to)20081-20087
Number of pages7
JournalJournal of Biological Chemistry
Issue number24
StatePublished - Jun 8 2012
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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