Characterization of the mouse interleukin-13 receptor α1 gene

Interleukin (IL)-13 is a pleiotropic immune regulatory cytokine that shares structural and biological characteristics with IL-4. The receptor for IL-13 is comprised of the IL-4 receptor α (IL-4Rα) subunit and a low-affinity IL-13-binding subunit, IL-13Rα1. An additional receptor, IL-13Rα2, binds to IL-13 with high affinity, but lacks the cytoplasmic domain for signaling. In this study, we isolated the mouse IL-13Rα1 gene (Il13ra1) of approximately 56 kb that spans the entire coding region. The mouse Il13ra1 gene is composed of 11 exons, and shows striking similarity in genomic structure to the previously reported class I cytokine receptor genes. Motifs characteristic of the cytokine receptor family are similarly organized on the genome, including conserved cysteines, a WSxWS motif, and Box1, indicating closely related genetic evolution of the cytokine receptor superfamily. Alternative mRNA splicings were demonstrated to generate variant transcripts that encode soluble IL-13Rα1. The mouse Il13ra1 gene was mapped to the proximal region of the mouse X chromosome, and was closely linked to the DXPas3 locus by interspecific backcross analysis. Il1ra1 mRNA was co-expressed with Il4ra mRNA in mouse myeloid and natural killer cells on which IL-13 has been known to act, whereas the Il13ra2 mRNA was not detected in these cells, indicating that IL-13Rα1 is the major component: of the IL-13 receptor complex in lymphohematopoietic cells.