We recently isolated a novel protein, SLAT, member of a novel subfamily of Rac-specific activators. SLAT is upregulated in Th2 cells and antigen stimulation induces its immune synapse localization and ZAP- 70 association, leading to reduced TCR recruitment and activation of ZAP-70. Our two, non-exclusive. working hypotheses are: 1) SLAT, via its association ZAP-70, inhibits the kinase's TCR recruitment and/or activation, thereby modulating the quality of TCR signaling in a manner that promotes Th2 differentiation, expansion and/or activation; and 2) SLAT and/or its alternative product, SLAT2, functions in Th2 cells as a Cdc42/Rac-specific GEF; this activity plays a non-redundant and unique role in determining the distinct quality of the IS and lipid raft clustering and, consequently, downstream signals, in Th2 cells. We will address these hypotheses and analyze other aspects of the expression, function and regulation of SLAT by exploring four aims: 1) Using primary mouse T cells, imaging and biochemical techniques, different stimuli, and receptor-blocking antibodies, we will analyze the expression of SLAT/SLAT2 mRNA or protein, study their intracellular localization, map residues essential for the membrane/IS localization, and assess the significance of this localization. 2) We will conduct a detailed analysis of SLAT1"""""""" mice, including Th1/Th2 differentiation, proximal and downstream signaling events, antibody and T cell responses, and susceptibility to experimental diseases that are associated with predominance of the Th1 or Th2 phenotype. 3) We will explore the biological relevance of the association between SLAT and ZAP-70 (or Syk) by mapping the interaction sites, and assessing the effects of interaction-deficient SLAT or ZAP-70/Syk mutants, or dominant negative ZAP-70/Syk, on Th1/Th1 development and activation. 4) We will use biochemical and genetic approaches, including SLAT1' mice or T cells reconstituted with SLAT mutants, to map the SLAT residues responsible for GEF activity, study mechanisms that regulate the GEF activity of SLAT, and determine the significance of this activity for the Th2-skewing effect of SLAT and for distinct organization of the IS in Th2 cells. These studies will characterize a novel, multifunctional TCR-proximal protein. ? ?

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Cellular and Molecular Immunology - B (CMI)
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Mallia, Conrad M
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La Jolla Institute
La Jolla
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Hashimoto, Marie; Nagao, Jun-Ichi; Ikezaki, Shojiro et al. (2017) Identification of a Novel Alternatively Spliced Form of Inflammatory Regulator SWAP-70-Like Adapter of T Cells. Int J Inflam 2017:1324735
Côte, Marjorie; Fos, Camille; Canonigo-Balancio, Ann J et al. (2015) SLAT promotes TCR-mediated, Rap1-dependent LFA-1 activation and adhesion through interaction of its PH domain with Rap1. J Cell Sci 128:4341-52
Fos, Camille; Becart, Stephane; Canonigo Balancio, Ann J et al. (2014) Association of the EF-hand and PH domains of the guanine nucleotide exchange factor SLAT with IP? receptor 1 promotes Ca²? signaling in T cells. Sci Signal 7:ra93
Feau, Sonia; Schoenberger, Stephen P; Altman, Amnon et al. (2013) SLAT regulates CD8+ T cell clonal expansion in a Cdc42- and NFAT1-dependent manner. J Immunol 190:174-83
Vistica, Barbara P; Shi, Guangpu; Nugent, Lindsey et al. (2012) SLAT/Def6 plays a critical role in the pathogenic process of experimental autoimmune uveitis (EAU). Mol Vis 18:1858-64
Singleton, Kentner L; Gosh, Monica; Dandekar, Radhika D et al. (2011) Itk controls the spatiotemporal organization of T cell activation. Sci Signal 4:ra66
Bécart, Stéphane; Altman, Amnon (2009) SWAP-70-like adapter of T cells: a novel Lck-regulated guanine nucleotide exchange factor coordinating actin cytoskeleton reorganization and Ca2+ signaling in T cells. Immunol Rev 232:319-33
Canonigo-Balancio, Ann J; Fos, Camille; Prod'homme, Thomas et al. (2009) SLAT/Def6 plays a critical role in the development of Th17 cell-mediated experimental autoimmune encephalomyelitis. J Immunol 183:7259-67
Mehta, Harshini; Glogauer, Michael; Bécart, Stephane et al. (2009) Adaptor protein SLAT modulates Fcgamma receptor-mediated phagocytosis in murine macrophages. J Biol Chem 284:11882-91
Becart, Stephane; Balancio, Ann J Canonigo; Charvet, Celine et al. (2008) Tyrosine-phosphorylation-dependent translocation of the SLAT protein to the immunological synapse is required for NFAT transcription factor activation. Immunity 29:704-19

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