title: Selective phosphorylation of the Dlg1AB variant is critical for TCR-induced p38 activation and induction of proinflammatory cytokines in CD8+ T cells.
abstract: CD8(+) T cells respond to TCR stimulation by producing proinflammatory cytokines, and destroying infected or malignant cells through the production and release of cytotoxic granules. Scaffold protein Discs large homolog 1 (Dlg1) specifies TCR-dependent functions by channeling proximal signals toward the activation of p38-dependent proinflammatory cytokine gene expression and/or p38-independent cytotoxic granule release. Two Dlg1 variants are expressed in CD8(+) T cells via alternative splicing, Dlg1AB and Dlg1B, which have differing abilities coordinate TCR-dependent functions. Although both variants facilitate p38-independent cytotoxicity, only Dlg1AB coordinates p38-dependent proinflammatory cytokine expression. In this study, we identify TCR-induced Dlg1 tyrosine phosphorylation as a key regulatory step required for Dlg1AB-mediated p38-dependent functions, including proinflammatory cytokine expression. We find that Dlg1AB but not Dlg1B is tyrosine phosphorylated by proximal tyrosine kinase Lck in response to TCR stimulation. Furthermore, we identify Dlg1 tyrosine 222 (Y222) as a major site of Dlg1 phosphorylation required for TCR-triggered p38 activation and NFAT-dependent expression of proinflammatory cytokines, but not for p38-independent cytotoxicity. Taken together, our data support a model where TCR-induced phosphorylation of Dlg1 Y222 is a key point of control that endows Dlg1AB with the ability to coordinate p38 activation and proinflammatory cytokine production. We propose blocking Dlg1AB phosphorylation as a novel therapeutic target to specifically block proinflammatory cytokine production but not cytotoxicity.
authors.affiliation: Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095;
authors.forename: Jillian
authors.initials: J
authors.lastname: Crocetti
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095;
authors.forename: Oscar
authors.initials: O
authors.lastname: Silva
authors.affiliation: Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095; Amgen, Thousand Oaks, CA 91320; and.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Humphries
authors.affiliation: Department of Psychology, University of California, Los Angeles, Los Angeles, CA 90095.
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Tibbs
authors.affiliation: Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095; Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095; cmiceli@ucla.edu.
authors.forename: M Carrie
authors.initials: MC
authors.lastname: Miceli
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002450:Cell Communication / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis*; D000074288:Discs Large Homolog 1 Protein; D004789:Enzyme Activation / Q000276:immunology; D007249:Inflammation / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000276:immunology*; D010766:Phosphorylation; D020033:Protein Isoforms / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D000074407:SAP90-PSD95 Associated Proteins; D016415:Sequence Alignment; D015398:Signal Transduction / Q000276:immunology; D014443:Tyrosine / Q000737:chemistry; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D016207:Cytokines; D000074288:Discs Large Homolog 1 Protein; C000614189:Dlg1 protein, mouse; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D011948:Receptors, Antigen, T-Cell; D000074407:SAP90-PSD95 Associated Proteins; D014443:Tyrosine; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D048051:p38 Mitogen-Activated Protein Kinases
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