title: Pre-existing clusters of the adaptor Lat do not participate in early T cell signaling events.
abstract: Engaged T cell antigen receptors (TCRs) initiate signaling through the adaptor protein Lat. In quiescent T cells, Lat is segregated into clusters on the cell surface, which raises the question of how TCR triggering initiates signaling. Using super-resolution fluorescence microscopy, we found that pre-existing Lat domains were neither phosphorylated nor laterally transported to TCR activation sites, which suggested that these clusters do not participate in TCR signaling. Instead, TCR activation resulted in the recruitment and phosphorylation of Lat from subsynaptic vesicles. Studies of Lat mutants confirmed that recruitment preceded and was essential for phosphorylation and that both processes were independent of surface clustering of Lat. Our data suggest that TCR ligation preconditions the membrane for vesicle recruitment and bulk activation of the Lat signaling network.
authors.affiliation: Centre for Vascular Research, University of New South Wales, Sydney, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Williamson
authors.forename: Dylan M
authors.initials: DM
authors.lastname: Owen
authors.forename: Jérémie
authors.initials: J
authors.lastname: Rossy
authors.forename: Astrid
authors.initials: A
authors.lastname: Magenau
authors.forename: Matthias
authors.initials: M
authors.lastname: Wehrmann
authors.forename: J Justin
authors.initials: JJ
authors.lastname: Gooding
authors.forename: Katharina
authors.initials: K
authors.lastname: Gaus
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods; D009154:Mutation; D010766:Phosphorylation; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism; D022142:Secretory Vesicles / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C110810:LAT protein, human; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell