Open Access

ARTICLE

Human IL-Rβ chains form IL-2 binding homodimers

Anne-Hélène Pillet^*, Olivier Juffroy^*, Virginie Mazard-Pasquier^*, Jean-Louis Moreau, Franck Gesbert, Patricia Chastagner, Jean-Hervé Colle, Jacques Thèze, Thierry Rose

Unité d’Immunogénétique Cellulaire, Département Infection et Epidémiologie, Institut Pasteur, Paris, France

* Corresponding Author: T. Rose,

European Cytokine Network 2008, 19(1), 49-59. https://doi.org/10.1684/ecn.2008.0120

Accepted 05 February 2008;

Abstract

Two types of functional interleukin-2 receptor (IL-2Rα/IL-2Rβ/γc and IL-2Rβ/γc) have already been characterized in humans. Here we describe a new form consisting of IL-2Rβ/β homodimers that assemble spontaneously in the absence of γc. Co-transfection of COS-7 cells with constructs expressing IL-2Rβ chains tagged with either HA or MYC sequences results in the formation of IL-2Rβ:HA/IL-2Rβ:MYC complexes detectable by coimmunoprecipitation. The formation of these IL-2Rβ:HA/IL-2Rβ:MYC dimers is also observed in the absence of IL-2. Moreover, in COS cells expressing chimeras of IL-2Rβ fused to fluorescence reporters such as IL-2Rβ:ECFP and IL-2Rβ:EYFP, we also observed specific FRET at the surface of living cells, as expected for dimer formation. Transiently transfected COS-7 cells expressing IL-2Rβ bind 125 I-labeled IL-2 (homodimers, Kd = 1nM) as cells expressing both IL-2Rβ and γc chains (heterodimers, Kd = 1 nM). IL-2Rβ/IL-2Rβ could represent either a decoy receptor or a new form of IL-2R involved in signaling when γc expression is low.

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Keywords

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