Cloning, chromosomal location, and tissue expression of the gene for pig interleukin-18.
Interleukin 18 (IL-18), a recently described cytokine, plays an important role in the cell-mediated immune response, in particular through its ability to induce the production of interferon (IFN)-gamma. We cloned pig IL-18 cDNA from the intestinal epithelial cell line IPI-2I using a reverse transcriptase-polymerase chain reaction method with primers derived from the human IL-18 sequence. The amino acid sequence deduced from pig IL-18 cDNA encodes a 192 amino-acid polypeptide that exhibits 92, 90, 81, and 71% similarity to IL-18 from horse, dog, human, and rodents (mouse and rat), respectively. Structural comparison of the IL-18 protein with IL-1alpha and IL-1beta showed that IL-18 shares several characteristics with the IL-1 cytokine family: the IL-1 signature-like sequence, a potential caspase-1 (ICE) cleavage site, and the presence of 12 predicted beta strands. Fluorescence in situ hybridization was used to localize the IL-18 gene on the short arm (p13) of pig chromosome 9. Analysis of IL-18 expression in different organs of piglets demonstrated that IL-18 mRNA is weakly expressed in the kidney and the lung. By contrast, we observed highly constitutive expression of IL-18 mRNA in the spleen, mesenteric lymph nodes, and the intestine, particularly in the small intestine, indicating a potential role for IL-18 as a first line of host defense in the intestinal mucosa.
Fournout
S
S
Laboratoire de Pharmacologie-Toxicologie, Institut National de Recherche Agronomique, Toulouse, France.
Dozois
C M
CM
Yerle
M
M
Pinton
P
P
Fairbrother
J M
JM
Oswald
E
E
Oswald
I P
IP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D017404:In Situ Hybridization, Fluorescence; D020382:Interleukin-18 / Q000235:genetics*; D007422:Intestines / Q000276:immunology; D008221:Lymphoid Tissue / Q000276:immunology; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D013552:Swine / Q000235:genetics* / Q000276:immunology; D014018:Tissue Distribution
D018076:DNA, Complementary; D020382:Interleukin-18; D012333:RNA, Messenger