Preassembly of interleukin 2 (IL-2) receptor subunits on resting Kit 225 K6 T cells and their modulation by IL-2, IL-7, and IL-15: A fluorescence resonance energy transfer study

Sándor Damjanovich, László Bene, János Matkó, Abdelkrim Alileche, Carolyn K. Goldman, Susan Sharrow, Thomas A. Waldmann

Research output: Contribution to journalArticle

117 Citations (Scopus)

Abstract

Assembly and mutual proximities of α, β, and γ(c) subunits of the interleukin 2 receptors (IL-2R) in plasma membranes of Kit 225 K6 T lymphoma cells were investigated by fluorescence resonance energy transfer (FRET) using fluorescein isothiocyanate- and Cy3-conjugated monoclonal antibodies (mAbs) that were directed against the IL-2Rα, IL-2Rβ, and γ(c) subunits of IL-2R. The cell-surface distribution of subunits was analyzed at the nanometer scale (2-10 nm) by FRET on a cell-by-cell basis. The cells were probed in resting phase and after coculture with saturating concentrations of IL-2, IL-7, and IL-15. FRET data from donor- and acceptor-labeled IL-2Rβ- α, γ-α, and γ-β pairs demonstrated close proximity of all subunits to each other in the plasma membrane of resting T cells. These mutual proximities do not appear to represent mAb-induced microaggregation, because FRET measurements with Fab fragments of the mAbs gave similar results. The relative proximities were meaningfully modulated by binding of IL-2, IL-7, and IL-15. Based on FRET analysis the topology of the three subunits at the surface of resting cells can be best described by a 'triangular model' in the absence of added interleukins. IL-2 strengthens the bridges between the subunits, making the triangle more compact. IL-7 and IL-15 act in the opposite direction by opening the triangle possibly because they associate their private specific a receptors with the β and/or γ(c) subunits of the IL-2R complex. These data suggest that IL-2R subunits are already colocalized in resting T cells and do not require cytokine-induced redistribution. This colocalization is significantly modulated by binding of relevant interleukins in a cytokine-specific manner.

Original languageEnglish
Pages (from-to)13134-13139
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume94
Issue number24
DOIs
Publication statusPublished - Nov 25 1997

Keywords

  • Cell activation
  • Cytokine binding
  • Receptor assembly

ASJC Scopus subject areas

  • General

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