title: Defining the functional binding sites of interleukin 12 receptor β1 and interleukin 23 receptor to Janus kinases.
abstract: The interleukin (IL)-12-type cytokines IL-12 and IL-23 are involved in T-helper (Th) 1 and Th17 immunity, respectively. They share the IL-12 receptor β1 (IL-12Rβ1) as one component of their receptor signaling complexes, with IL-12Rβ2 as second receptor for IL-12 and IL-23R for IL-23 signal transduction. Stimulation with IL-12 and IL-23 results in activation of receptor-associated Janus kinases (Jak) and phosphorylation of STAT proteins in target cells. The Janus kinase tyrosine kinase (Tyk) 2 associates with IL-12Rβ1, whereas Jak2 binds to IL-23R and also to IL-12Rβ2. Receptor association of Jak2 is mediated by Box1 and Box2 motifs located within the intracellular domain of the receptor chains. Here we define the Box1 and Box2 motifs in IL-12Rβ1 and an unusual Jak2-binding site in IL-23R by the use of deletion and site-directed mutagenesis. Our data show that nonfunctional box motifs abolish IL-12- and IL-23-induced STAT3 phosphorylation and cytokine-dependent proliferation of Ba/F3 cells. Coimmunoprecipitation of Tyk2 by IL-12Rβ1 and Jak2 by IL‑23R supported these findings. In addition, our data demonstrate that association of Jak2 with IL-23R is mandatory for IL-12 and/or IL-23 signaling, whereas Tyk2 seems to be dispensable.
authors.affiliation: Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, D-40225 Düsseldorf, Germany doreen.floss@uni-duesseldorf.de jscheller@uni-duesseldorf.de.
authors.forename: Doreen M
authors.initials: DM
authors.lastname: Floss
authors.affiliation: Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, D-40225 Düsseldorf, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Klöcker
authors.affiliation: Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, D-40225 Düsseldorf, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Schröder
authors.affiliation: Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, D-40225 Düsseldorf, Germany.
authors.forename: Larissa
authors.initials: L
authors.lastname: Lamertz
authors.affiliation: Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, D-40225 Düsseldorf, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Mrotzek
authors.affiliation: Institute of Animal Breeding and Genetics/Biomodels Austria, University of Veterinary Medicine, A-1210 Vienna, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Strobl
authors.affiliation: Medical Clinic II, Division of Hepatology, University Hospital Würzburg, D-97080 Würzburg, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Hermanns
authors.affiliation: Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, D-40225 Düsseldorf, Germany doreen.floss@uni-duesseldorf.de jscheller@uni-duesseldorf.de.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Scheller
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops / Q000276:immunology; D006801:Humans; D018664:Interleukin-12 / Q000378:metabolism; D053759:Interleukin-23 / Q000378:metabolism; D053760:Interleukin-23 Subunit p19; D053614:Janus Kinase 2 / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D018123:Receptors, Interleukin / Q000378:metabolism*; D053707:Receptors, Interleukin-12 / Q000378:metabolism*; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D053634:TYK2 Kinase / Q000378:metabolism
chemical_list: C508438:IL12RB1 protein, human; C508840:IL23A protein, human; C515500:IL23R protein, human; D053759:Interleukin-23; D053760:Interleukin-23 Subunit p19; D018123:Receptors, Interleukin; D053707:Receptors, Interleukin-12; D050796:STAT3 Transcription Factor; D018664:Interleukin-12; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D053634:TYK2 Kinase