The phosphorylation state of CD3gamma influences T cell responsiveness and controls T cell receptor cycling

J Biol Chem. 1998 Sep 11;273(37):24232-8. doi: 10.1074/jbc.273.37.24232.

Abstract

The T cell receptor (TCR) is internalized following activation of protein kinase C (PKC) via a leucine (Leu)-based motif in CD3gamma. Some studies have indicated that the TCR is recycled back to the cell surface following PKC-mediated internalization. The functional state of recycled TCR and the mechanisms involved in the sorting events following PKC-induced internalization are not known. In this study, we demonstrated that following PKC-induced internalization, the TCR is recycled back to the cell surface in a functional state. TCR recycling was dependent on dephosphorylation of CD3gamma, probably mediated by the serine/threonine protein phosphatase-2A, but independent on microtubules or actin polymerization. Furthermore, in contrast to ligand-mediated TCR sorting, recycling of the TCR was independent of the tyrosine phosphatase CD45 and the Src tyrosine kinases p56(Lck) and p59(Fyn). Studies of mutated TCR and chimeric CD4-CD3gamma molecules demonstrated that CD3gamma did not contain a recycling signal in itself. In contrast, the only sorting information in CD3gamma was the Leu-based motif that mediated lysosomal sorting of chimeric CD4-CD3gamma molecules. Finally, we found a correlation between the phosphorylation state of CD3gamma and T cell responsiveness. Based on these observations a physiological role of CD3gamma and TCR cycling is proposed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antigens, CD / metabolism
  • Biotinylation
  • CD4 Antigens / metabolism
  • Calcium / metabolism
  • Cell Membrane / immunology
  • Cytosol / metabolism
  • Humans
  • Jurkat Cells / drug effects
  • Jurkat Cells / immunology*
  • Kinetics
  • Leucine
  • Leukocyte Common Antigens / metabolism
  • Lysosomes / immunology
  • Molecular Sequence Data
  • Phorbol 12,13-Dibutyrate / pharmacology
  • Phosphoprotein Phosphatases / metabolism
  • Phosphorylation
  • Protein Phosphatase 2
  • Protein-Tyrosine Kinases / metabolism
  • Receptor-CD3 Complex, Antigen, T-Cell / chemistry
  • Receptor-CD3 Complex, Antigen, T-Cell / physiology*
  • Receptors, Antigen, T-Cell / physiology*
  • Receptors, Antigen, T-Cell, gamma-delta / chemistry
  • Receptors, Antigen, T-Cell, gamma-delta / physiology*
  • Recombinant Fusion Proteins / metabolism
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / immunology*
  • Transfection

Substances

  • Antigens, CD
  • CD4 Antigens
  • Receptor-CD3 Complex, Antigen, T-Cell
  • Receptors, Antigen, T-Cell
  • Receptors, Antigen, T-Cell, gamma-delta
  • Recombinant Fusion Proteins
  • Phorbol 12,13-Dibutyrate
  • Protein-Tyrosine Kinases
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 2
  • Leukocyte Common Antigens
  • Leucine
  • Calcium