title: Molecular cloning, characterization and expression analysis of an IL-21 homologue from Tetraodon nigroviridis.
abstract: Interleukin-21 (IL-21) is an important immune cytokine that was well characterized in human and mammals, but little is known in fish. In present study, an IL-21 homologue was cloned and well characterized from Tetraodon nigroviridis. The full-length Tetraodon IL-21 cDNA was 849bp in size, containing an open reading frame (ORF) of 438bp that translated a 145 amino-acid peptide, a 5' untranslated region (UTR) of 69bp, and a 3' UTR of 342bp. The deduced peptide shared identity of 20-49% with other known IL-21 sequences. The Tetraodon IL-21 gene had six exons while both human and Takifugu IL-21 gene contained only five exons. However, the level of synteny between human, Takifugu and Tetraodon genomes was well conserved during evolution. In vivo expression study showed that Tetraodon IL-21 mRNAs were constitutively expressed at a low level and only in limited tissues, including gut, gill and gonad in healthy fish, and stimulation with LPS increased the expression of IL-21 in these tissues and induced the expression of IL-21 in kidney, spleen and skin, indicating that IL-21 is an inflammatory stress inducible gene associated with the anti-bacterial defense in fish. Our study provided further evidence for the existence of IL-21 in fish, and gained further insight into the immunological functions of IL-21 gene in fish.
authors.affiliation: College of Life Sciences, Zhejiang University, Hangzhou 310012, PR China.
authors.forename: Hui-Ju
authors.initials: HJ
authors.lastname: Wang
authors.forename: Li-Xin
authors.initials: LX
authors.lastname: Xiang
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Shao
authors.forename: Shen
authors.initials: S
authors.lastname: Jia
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D029941:Fish Proteins / Q000235:genetics* / Q000276:immunology*; D015870:Gene Expression; D006801:Humans; D007378:Interleukins / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D023721:Tetraodontiformes / Q000235:genetics* / Q000276:immunology*; D014018:Tissue Distribution; D000098546:Interleukin-21
chemical_list: D018076:DNA, Complementary; D029941:Fish Proteins; D007378:Interleukins; D000098546:Interleukin-21