Characterization of the mouse interleukin-13 receptor alpha 1 gene

Interleukin (IL)-13 is a pleiotropic immune regulatory cytokine that shares structural and biological characteristics with IL-4. The receptor for IL-1 3 is comprised of the IL-4 receptor alpha (IL-4R alpha) subunit and a low-a ffinity IL-13-binding subunit, IL-13R alpha 1. An additional receptor, IL-1 3R alpha 2, binds to IL-13 with high affinity, but lacks the cytoplasmic do main for signaling. In this study, we isolated the mouse IL-13R alpha 1 gen e (I113ra1) of approximately 56 kb that spans the entire coding region. The mouse I113ra1 gene is composed of 11 exons, and shows striking similarity in genomic structure to the previously reported class I cytokine receptor g enes. Motifs characteristic of the cytokine receptor family are similarly o rganized on the genome, including conserved cysteines, a WSxWS motif, and B ox1, indicating closely related genetic evolution of the cytokine receptor superfamily. Alternative mRNA splicings were demonstrated to generate varia nt transcripts that encode soluble IL-13Ra1, The mouse Il13ra1 gene was map ped to the proximal region of the mouse X chromosome, and was closely linke d to the DXPas3 locus by interspecific backcross analysis. Il13ra1 mRNA was co-ex-pressed 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 detect ed in these cells, indicating that IL-13R alpha 1 is the major component of the IL-13 receptor complex in lymphohematopoietic cells.