Imaging antigen-induced PI3K activation in T cells.
Activation of phosphoinositide 3-kinase (PI3K) at the immunological synapse between a T cell and an antigen-presenting cell (APC) has not been demonstrated. Using fluorescent-specific probes, we show here that the formation of an immunological synapse led to sustained production of 3'-phosphoinositides in the T cell, whereby phosphatidylinositol-3,4,5-trisphosphate (PIP3) but not phosphatidylinositol-3,4-bisphosphate was localized to the cell membrane. The accumulation of PIP3 after T cell activation preceded the increase in intracellular calcium. Neither the formation of conjugates between T cells and APCs nor signaling events such as phosphotyrosine accumulation and calcium increase changed substantially when PI3K was inhibited, and only a limited reduction in synthesis of interleukin 2 occurred. In T cell-APC conjugates, PIP3 accumulated at the T cell-APC synapse as well as in the rest of the T cell plasma membrane, which indicated unusual regulation of PI3K activity during antigen presentation.
Harriague
Julie
J
Département de Biologie Cellulaire, Institut Cochin, INSERM U567, CNRS UMR 7627, Université René Descartes, 22 rue Méchain, 75014 Paris, France.
Bismuth
Georges
G
D000818:Animals; D017951:Antigen Presentation / Q000502:physiology*; D000938:Antigen-Presenting Cells / Q000276:immunology*; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D003713:Dendritic Cells / Q000276:immunology; D004789:Enzyme Activation; D005347:Fibroblasts / Q000276:immunology; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D007376:Interleukin-2 / Q000096:biosynthesis; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D008563:Membrane Lipids / Q000378:metabolism*; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011993:Recombinant Fusion Proteins / Q000032:analysis; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology / Q000648:ultrastructure
D049452:Green Fluorescent Proteins; D007376:Interleukin-2; D008164:Luminescent Proteins; D008563:Membrane Lipids; D019869:Phosphatidylinositol 3-Kinases; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011993:Recombinant Fusion Proteins; C060974:phosphatidylinositol 3,4,5-triphosphate