Interleukin-12 receptor β2 (IL-12Rβ2) is a signaling subunit of heterodimeric receptors for IL-12 and IL-35. It plays important regulatory functions in the development of Th1 cells and in the expression of inflammatory cytokines in mammals and other higher vertebrates. However， little is known about IL-12Rβ2 in teleost fish. In this work， we have cloned and characterized IL-12Rβ2 from grass carp (Ctenopharyngodon idella). The full-length cDNA of grass carp IL-12Rβ2 is 2875 bp， which encodes a mature protein with 741 amino acids. This mature protein contains three fibronectin type III domains， a transmembrane helix， and CXW and WSXWS-like motifs that are characteristic of the type I cytokine recep... More
Interleukin-12 receptor β2 (IL-12Rβ2) is a signaling subunit of heterodimeric receptors for IL-12 and IL-35. It plays important regulatory functions in the development of Th1 cells and in the expression of inflammatory cytokines in mammals and other higher vertebrates. However， little is known about IL-12Rβ2 in teleost fish. In this work， we have cloned and characterized IL-12Rβ2 from grass carp (Ctenopharyngodon idella). The full-length cDNA of grass carp IL-12Rβ2 is 2875 bp， which encodes a mature protein with 741 amino acids. This mature protein contains three fibronectin type III domains， a transmembrane helix， and CXW and WSXWS-like motifs that are characteristic of the type I cytokine receptor family. Phylogenetic analysis revealed that cyprinid fish IL-12Rβ2 formed a single branch， clearly separated from those of other vertebrates. We expressed and purified a recombinant grass carp IL-12Rβ2 protein containing major antigenic regions， which was used to raise a polyclonal antibody. The specificity of the antibody was assessed by Western blotting analysis of whole cell lysates from Escherichia coli cells expressing the recombinant IL-12Rβ2， grass carp intestinal intraepithelial lymphocytes， and cultured C. idella kidney cells. To explore the potential regulatory role of IL-12Rβ2 in inflammation， we generated an intestinal inflammation model by anal intubation of fish with Aeromonas hydrophila. Immunohistochemical staining of the inflamed intestines revealed that IL-12Rβ2 expression is consistent with inflammatory cell recruitment during intestinal inflammation. Real-time quantitative PCR revealed that IL-12Rβ2 is widely expressed in normal tissues and is up-regulated in most tissues after infecting with A. hydrophila. We found that IL-12Rβ2， IL-12p35， and interferon-γ were expressed in similar patterns in the intestines during inflammation. Taken together， our results suggest that IL-12Rβ2 is involved in the regulation of intestinal inflammation.
