Imaging antigen-induced PI3K activation in T cells

Nat Immunol. 2002 Nov;3(11):1090-6. doi: 10.1038/ni847. Epub 2002 Oct 21.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigen Presentation / physiology*
  • Antigen-Presenting Cells / immunology*
  • Calcium Signaling
  • Cell Membrane / metabolism*
  • Cells, Cultured / immunology
  • Cells, Cultured / metabolism
  • Cells, Cultured / ultrastructure
  • Dendritic Cells / immunology
  • Enzyme Activation
  • Fibroblasts / immunology
  • Genes, Reporter
  • Green Fluorescent Proteins
  • Humans
  • Hybridomas / immunology
  • Interleukin-2 / biosynthesis
  • Luminescent Proteins / analysis
  • Luminescent Proteins / genetics
  • Membrane Lipids / metabolism*
  • Mice
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphatidylinositol 4,5-Diphosphate / metabolism
  • Phosphatidylinositol Phosphates / metabolism*
  • Phosphorylation
  • Protein Processing, Post-Translational
  • Protein Structure, Tertiary
  • Protein Transport
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Recombinant Fusion Proteins / analysis
  • T-Lymphocytes / enzymology*
  • T-Lymphocytes / immunology
  • T-Lymphocytes / ultrastructure

Substances

  • Interleukin-2
  • Luminescent Proteins
  • Membrane Lipids
  • Phosphatidylinositol 4,5-Diphosphate
  • Phosphatidylinositol Phosphates
  • Proto-Oncogene Proteins
  • Recombinant Fusion Proteins
  • phosphatidylinositol 3,4,5-triphosphate
  • Green Fluorescent Proteins
  • Phosphatidylinositol 3-Kinases
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt