Cloning,Expression Analyses,and Chromosomal Location of Porcine Interleukin-18 Receptor α Chain (IL-18R α )

Abstract

We cloned and sequenced a cDNA that contains the coding sequence of the porcine interleukin-18 receptor α chain (PoIL-18Rα). Based on the conserved nucleotide sequences between human (HuIL-18Rα) and murine IL-18Rα (MuIL-18Rα), we performed reverse transcription-polymerase chain reaction (RT-PCR) with total RNA prepared from porcine peripheral blood lymphocytes (PBLs) stimulated with PoIL-12 to clone the cDNA of PoIL-18Rα. The open reading frame (ORF) of the PoIL-18Rα cDNA is 1620 base pairs (bp) in length and encodes 539 amino acids. The predicted amino acid sequence showed 68.2% and 50.2% identity to the human and murine amino acid sequences, respectively. Stimulation with concanavalin A (ConA) and IL-12, but not with IL-4, was shown to upregulate the expression of IL-18Rα mRNA in pig PBLs by RT-PCR analysis. Flow cytometric analysis also demonstrated that IL-18Rα was constitutively expressed on PoPBLs, and this expression was augmented by ConA stimulation. Furthermore, the PoIL-18Rα gene was mapped by fluorescence in situ hybridization (FISH) to porcine chromosome 3 (3q13-q14), near the location at which the IL-1β gene had already been mapped. The present results will be helpful for understanding PoIL-18 and interferon γ (IFN-γ)-mediated T helper 1 (Th1) cell development.