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    Immunity. 2008 Jun;28(6):810-21.

    T cell costimulation via the integrin VLA-4 inhibits the actin-dependent centralization of signaling microclusters containing the adaptor SLP-76.

    Nguyen K, Sylvain NR, Bunnell SC.

    Program in Immunology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA.

    Comment in:

    Antigen-dependent T cell activation drives the formation of signaling microclusters containing the adaptor SLP-76. Costimulatory integrins regulate SLP-76 phosphorylation and could influence SLP-76 microclusters in the integrin-rich periphery of the immune synapse. We report that costimulation by the integrin VLA-4 (alpha4beta1) required SLP-76 domains implicated in microcluster assembly. Pro-adhesive ligands enlarged the contact and increased the number of SLP-76 microclusters regardless of their costimulatory potential. Costimulatory VLA-4 ligands also prevented the centralization of SLP-76, promoted microcluster persistence, prolonged lateral interactions between SLP-76 and its upstream kinase, ZAP-70, and retained SLP-76 in tyrosine-phosphorylated peripheral structures. SLP-76 centralization was driven by dynamic actin polymerization and was correlated with inward actin flows. VLA-4 ligation retarded these flows, even in the absence of SLP-76. These data suggest a widely applicable model of costimulation, in which integrins promote sustained signaling by attenuating cytoskeletal movements that drive the centralization and inactivation of SLP-76 microclusters.

    PMID: 18549800 [PubMed - indexed for MEDLINE]

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