T cell activation initiates protective adaptive immunity, but counterbalancing mechanisms are critical to prevent overshooting responses and to maintain immune homeostasis. The CARD11-BCL10-MALT1 (CBM) complex bridges T cell receptor engagement to NF-κB signaling and MALT1 protease activation. Here, we show that ABIN-1 is modulating the suppressive function of A20 in T cells. Using quantitative mass spectrometry, we identified ABIN-1 as an interactor of the CBM signalosome in activated T cells. A20 and ABIN-1 counteract inducible activation of human primary CD4 and Jurkat T cells. While A20 overexpression is able to silence CBM complex-triggered NF-κB and MALT1 protease activation independent of ABIN-1, the negative regulatory function of ABIN-1 depends on A20. The suppressive function of A20 in T cells relies on ubiquitin binding through the C-terminal zinc finger (ZnF)4/7 motifs, but does not involve the deubiquitinating activity of the OTU domain. Our mechanistic studies reveal that the A20/ABIN-1 module is recruited to the CBM complex via A20 ZnF4/7 and that proteasomal degradation of A20 and ABIN-1 releases the CBM complex from the negative impact of both regulators. Ubiquitin binding to A20 ZnF4/7 promotes destructive K48-polyubiquitination to itself and to ABIN-1. Further, after prolonged T cell stimulation, ABIN-1 antagonizes MALT1-catalyzed cleavage of re-synthesized A20 and thereby diminishes sustained CBM complex signaling. Taken together, interdependent post-translational mechanisms are tightly controlling expression and activity of the A20/ABIN-1 silencing module and the cooperative action of both negative regulators is critical to balance CBM complex signaling and T cell activation.
- Yin, H.
- Karayel, O.
- Chao, Y. Y.
- Seeholzer, T.
- Hamp, I.
- Plettenburg, O.
- Gehring, T.
- Zielinski, C.
- Mann, M.
- Krappmann, D.
Keywords
- B-Cell CLL-Lymphoma 10 Protein/metabolism
- CARD Signaling Adaptor Proteins/metabolism
- Cells, Cultured
- DNA-Binding Proteins/*physiology
- Guanylate Cyclase/metabolism
- HEK293 Cells
- Humans
- Jurkat Cells
- Lymphocyte Activation/genetics
- Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein/metabolism
- Multiprotein Complexes/metabolism
- NF-kappa B/metabolism
- Protein Binding
- RNA Interference/immunology
- Signal Transduction/physiology
- T-Lymphocytes/immunology/*metabolism
- Tumor Necrosis Factor alpha-Induced Protein 3/*physiology
- Carma1
- Immune activation
- Immune suppression
- T cell signaling
- Tnfaip3
- Tnip1