Galectin-3 negatively regulates TCR-mediated CD4+ T-cell activation at the immunological synapse

Proc Natl Acad Sci U S A. 2009 Aug 25;106(34):14496-501. doi: 10.1073/pnas.0903497106. Epub 2009 Aug 12.

Abstract

We have investigated the function of endogenous galectin-3 in T cells. Galectin-3-deficient (gal3(-/-)) CD4(+) T cells secreted more IFN-gamma and IL-4 than gal3(+/+)CD4(+) T cells after T-cell receptor (TCR) engagement. Galectin-3 was recruited to the cytoplasmic side of the immunological synapse (IS) in activated T cells. In T cells stimulated on supported lipid bilayers, galectin-3 was primarily located at the peripheral supramolecular activation cluster (pSMAC). Gal3(+/+) T cells formed central SMAC on lipid bilayers less effectively and adhered to antigen-presenting cells less firmly than gal3(-/-) T cells, suggesting that galectin-3 destabilizes the IS. Galectin-3 expression was associated with lower levels of early signaling events and phosphotyrosine signals at the pSMAC. Additional data suggest that galectin-3 potentiates down-regulation of TCR in T cells. By yeast two-hybrid screening, we identified as a galectin-3-binding partner, Alix, which is known to be involved in protein transport and regulation of cell surface expression of certain receptors. Co-immunoprecipitation confirmed galectin-3-Alix association and immunofluorescence analysis demonstrated the translocation of Alix to the IS in activated T cells. We conclude that galectin-3 is an inhibitory regulator of T-cell activation and functions intracellularly by promoting TCR down-regulation, possibly through modulating Alix's function at the IS.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • CD4-Positive T-Lymphocytes / cytology
  • CD4-Positive T-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / metabolism
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Line
  • Endosomal Sorting Complexes Required for Transport
  • Galectin 3 / genetics
  • Galectin 3 / metabolism*
  • Humans
  • Immunoblotting
  • Immunological Synapses / immunology*
  • Immunoprecipitation
  • Interferon-gamma / biosynthesis
  • Interleukin-4 / biosynthesis
  • Jurkat Cells
  • Lymphocyte Activation / immunology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Protein Binding
  • Receptors, Antigen, T-Cell / immunology*
  • Receptors, Antigen, T-Cell / metabolism
  • Signal Transduction / immunology
  • Transfection
  • Two-Hybrid System Techniques

Substances

  • Calcium-Binding Proteins
  • Cell Cycle Proteins
  • Endosomal Sorting Complexes Required for Transport
  • Galectin 3
  • PDCD6IP protein, human
  • Pdcd6ip protein, mouse
  • Receptors, Antigen, T-Cell
  • Interleukin-4
  • Interferon-gamma