SKAP1 protein PH domain determines RapL membrane localization and Rap1 protein complex formation for T cell receptor (TCR) activation of LFA-1

J Biol Chem. 2011 Aug 26;286(34):29663-70. doi: 10.1074/jbc.M111.222661. Epub 2011 Jun 13.

Abstract

Although essential for T cell function, the identity of the T cell receptor (TCR) "inside-out" pathway for the activation of lymphocyte function-associated antigen 1 (LFA-1) is unclear. SKAP1 (SKAP-55) is the upstream regulator needed for TCR-induced RapL-Rap1 complex formation and LFA-1 activation. In this paper, we show that SKAP1 is needed for RapL binding to membranes in a manner dependent on the PH domain of SKAP1 and the PI3K pathway. A SKAP1 PH domain-inactivating mutation (i.e. R131M) markedly impaired RapL translocation to membranes for Rap1 and LFA-1 binding and the up-regulation of LFA-1-intercellular adhesion molecule 1 (ICAM-1) binding. Further, N-terminal myr-tagged SKAP1 for membrane binding facilitated constitutive RapL membrane and Rap1 binding and effectively substituted for PI3K and TCR ligation in the activation of LFA-1 in T cells.

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Apoptosis Regulatory Proteins
  • Cell Membrane / genetics
  • Cell Membrane / metabolism
  • Humans
  • Intercellular Adhesion Molecule-1 / genetics
  • Intercellular Adhesion Molecule-1 / metabolism
  • Jurkat Cells
  • Lymphocyte Function-Associated Antigen-1 / biosynthesis*
  • Lymphocyte Function-Associated Antigen-1 / genetics
  • Monomeric GTP-Binding Proteins / genetics
  • Monomeric GTP-Binding Proteins / metabolism*
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism
  • Mutation
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Protein Structure, Tertiary
  • Protein Transport / physiology
  • Receptors, Antigen, T-Cell / genetics
  • Receptors, Antigen, T-Cell / metabolism*
  • Shelterin Complex
  • T-Lymphocytes / metabolism*
  • Telomere-Binding Proteins / genetics
  • Telomere-Binding Proteins / metabolism*
  • Up-Regulation / physiology

Substances

  • Adaptor Proteins, Signal Transducing
  • Apoptosis Regulatory Proteins
  • Lymphocyte Function-Associated Antigen-1
  • Multiprotein Complexes
  • Phosphoproteins
  • RASSF5 protein, human
  • Receptors, Antigen, T-Cell
  • SKAP1 protein, human
  • Shelterin Complex
  • TERF2IP protein, human
  • Telomere-Binding Proteins
  • Intercellular Adhesion Molecule-1
  • Monomeric GTP-Binding Proteins