Tyrosine-Phosphorylation-Dependent Translocation of the SLAT Protein to the Immunological Synapse Is Required for NFAT Transcription Factor Activation

Abstract

SUMMARY SWAP-70-like adaptor of T cells (SLAT) is a guanine nucleotide exchange factor for Rho GTPases that regulates the development of T helper 1 (Th1) and Th2 cell inflammatory responses by controlling the Ca2+-NFAT signaling pathway. However, the mechanism used by SLAT to regulate these events is unknown. Here, we report that the T cell receptor (TCR)-induced translocation of SLAT to the immunological synapse required Lck-mediated phosphorylation of two tyrosine residues located in an immunoreceptor tyrosine-based activation motif-like sequence but was independent of the SLAT PH domain. This subcellular relocalization was coupled to, and necessary for, activation of the NFAT pathway. Furthermore, membrane targeting of the SLAT Dbl-homology (catalytic) domain was sufficient to trigger TCR-mediated NFAT activation and Th1 and Th2 differentiation in a Cdc42-dependent manner. Therefore, tyrosine-phosphorylation-mediated relocalization of SLAT to the site of antigen recognition is required for SLAT to exert its pivotal role in NFAT-dependent CD4+ T cell differentiation.

Foxo1 Is a T Cell–Intrinsic Inhibitor of the RORγt-Th17 Program

“…The mutant FOXO1TMDDBD/pMIT has been generated using the primers (59-.39) huFOXO1DDBD (forward), 59-GGGCCGCTCGCGGGGCAG CCGAGTAAATTTGCTAAGAGCCGA-39 and huFOXO1DDBD (reverse), 59-TCGGCTCTTAGCAAATTTACTC-GGCTGCCCCGCGAGCGGCCC-39 and the mutagenesis kit XL (Stratagene, Santa Clara, CA). Viruses were produced according to the protocol described, with some changes (31). Briefly, Platinum-E packaging cells (plat-E) (32) were seeded in 10 ml DMEM plus 10% FCS at 2.5 3 10 6 cells/ml in a 10-cm dish.…”

Loss of Allograft Inflammatory Factor-1 Ameliorates Experimental Autoimmune Encephalomyelitis by Limiting Encephalitogenic CD4 T-Cell Expansion

“…-activated NFAT (nuclear factor of activated T-cells) transcription factors (41,42). It is possible that effects on actin cytoskeletal remodeling, Rac activation and/or Ca 2+ handling due to loss of Aif-1 impinge negatively on signaling pathways that support T-cell inflammatory gene expression.…”

DEF6, a Novel Substrate for the Tec Kinase ITK, Contains a Glutamine-rich Aggregation-prone Region and Forms Cytoplasmic Granules that Co-localize with P-bodies

“…It is one of a complement of signaling molecules that function downstream of the T cell receptor at the immune synapse, a junction between T cells and antigen presenting cells, where it has been identified to play a role in coordinating actin cytoskeleton remodeling, and Ca 2ϩ and NFAT signaling (5,6). Inactivation of DEF6 expression by retroviral insertion in transgenic mice has also identified a role for DEF6 in regulating the expression of the inflammatory interleukin IL-17 (7,8), although whether DEF6 acts as a positive or negative regulator remains to be clarified.…”

“…Phosphorylation by LCK has been found to be necessary for recruitment of DEF6 to the immune synapse (11). Initial studies identified tyrosine 210 of DEF6 as the residue phosphorylated by LCK (11) but subsequently tyrosines 133 and 144 were shown to be LCK targets (5). However, the dynamic structure of the immune synapse is regulated extensively through the activity of different families of kinase other than LCK including the Syk-family kinase ZAP-70 and the Tec-family kinase, ITK (12)(13)(14), and given that ITKdeficient mice exhibited a very similar phenotype to the DEF6-deficent mice (7,8,15), we explored the possibility that, in addition to LCK, DEF6 might be a substrate of ITK.…”