title: Human IL-Rbeta chains form IL-2 binding homodimers.
abstract: Two types of functional interleukin-2 receptor (IL-2Ralpha/IL-2Rbeta/gammac and IL-2Rbeta/gammac) have already been characterized in humans. Here we describe a new form consisting of IL-2Rbeta/beta homodimers that assemble spontaneously in the absence of gammac. Co-transfection of COS-7 cells with constructs expressing IL-2Rbeta chains tagged with either HA or MYC sequences results in the formation of IL-2Rbeta:HA/IL-2Rbeta:MYC complexes detectable by coimmunoprecipitation. The formation of these IL-2Rbeta:HA/IL-2Rbeta:MYC dimers is also observed in the absence of IL-2. Moreover, in COS cells expressing chimeras of IL-2Rbeta fused to fluorescence reporters such as IL-2Rbeta:ECFP and IL-2Rbeta:EYFP, we also observed specific FRET at the surface of living cells, as expected for dimer formation. Transiently transfected COS-7 cells expressing IL-2Rbeta bind 125I-labeled IL-2 (homodimers, Kd = 1nM) as cells expressing both IL-2Rbeta and gammac chains (heterodimers, Kd = 1 nM). IL-2Rbeta/IL-2Rbeta could represent either a decoy receptor or a new form of IL-2R involved in signaling when gammac expression is low.
authors.affiliation: Unité d'Immunogénétique Cellulaire, Département Infection et Epidémiologie, Institut Pasteur, Paris, France.
authors.forename: Anne-Hélène
authors.initials: AH
authors.lastname: Pillet
authors.forename: Olivier
authors.initials: O
authors.lastname: Juffroy
authors.forename: Virginie
authors.initials: V
authors.lastname: Mazard-Pasquier
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Moreau
authors.forename: Franck
authors.initials: F
authors.lastname: Gesbert
authors.forename: Patricia
authors.initials: P
authors.lastname: Chastagner
authors.forename: Jean-Hervé
authors.initials: JH
authors.lastname: Colle
authors.forename: Jacques
authors.initials: J
authors.lastname: Thèze
authors.forename: Thierry
authors.initials: T
authors.lastname: Rose
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D019281:Dimerization; D031541:Fluorescence Resonance Energy Transfer; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000737:chemistry* / Q000235:genetics; D053646:Interleukin-2 Receptor beta Subunit / Q000737:chemistry* / Q000235:genetics; D008954:Models, Biological; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D014162:Transfection
chemical_list: D007376:Interleukin-2; D053646:Interleukin-2 Receptor beta Subunit