SKAP55 coupled with CD45 positively regulates T-cell receptor-mediated gene transcription

Mol Cell Biol. 2002 Apr;22(8):2673-86. doi: 10.1128/MCB.22.8.2673-2686.2002.

Abstract

CD45 plays a critical role in T-cell receptor (TCR)-mediated signaling. In a yeast two-hybrid screen, SKAP55, the Src kinase-associated phosphoprotein of unknown function, was found as a substrate which associated with CD45 in vivo. Mutational analysis demonstrated the pivotal role of Tyr-232 in SKAP55 in the association with CD45. In Jurkat cells, anti-CD3 antibody stimulation promoted SKAP55 tyrosine phosphorylation and translocation from the cytoplasm to the membrane. Overexpression of SKAP55 in these cells induced transcriptional activation of the IL-2 promoter, while mutant SKAP55-Y232F totally suppressed the promoter activity. Furthermore, overexpression of SKAP55-Y232F also caused the tyrosine hyperphosphorylation of Fyn with a decreased kinase activity. Thus, SKAP55 is an essential adapter to couple CD45 with the Src family kinases for dephosphorylation and, thus, positively regulates TCR signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies / pharmacology
  • Binding Sites
  • Biological Transport, Active
  • CD3 Complex / metabolism
  • Cell Membrane / metabolism
  • Cytoplasm / metabolism
  • Humans
  • Interleukin-2 / genetics
  • Jurkat Cells
  • Leukocyte Common Antigens / chemistry
  • Leukocyte Common Antigens / genetics
  • Leukocyte Common Antigens / metabolism*
  • Mutagenesis, Site-Directed
  • Phosphoproteins / chemistry
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Promoter Regions, Genetic
  • Protein Structure, Tertiary
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-fyn
  • Receptors, Antigen, T-Cell / genetics
  • Receptors, Antigen, T-Cell / metabolism*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Signal Transduction
  • Substrate Specificity
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism
  • Transcription, Genetic
  • Two-Hybrid System Techniques
  • Tyrosine / metabolism

Substances

  • Antibodies
  • CD3 Complex
  • Interleukin-2
  • Phosphoproteins
  • Proto-Oncogene Proteins
  • Receptors, Antigen, T-Cell
  • Recombinant Proteins
  • SKAP1 protein, human
  • Tyrosine
  • FYN protein, human
  • Proto-Oncogene Proteins c-fyn
  • Leukocyte Common Antigens