title: Identification and characterization of an interleukin-15 homologue from Tetraodon nigroviridis.
abstract: Interleukin-15 (IL-15) plays an important role in adaptive immune systems in vertebrates with similar bioactivities to interleukin-2 (IL-2). Here we report molecular cloning, sequence analysis and distribution of an IL-15 homologue from a pufferfish (Tetraodon nigroviridis). It is located within a 3,088 bp genomic fragment, transcribed into a 1,056 bp mRNA including 158 bp 5'UTR (untranslated region), 519 bp ORF (open reading frame) and 379 bp 3'UTR. T. nigroviridis IL-15 is constitutively detectable in tissues and organs selected. Levels of transcripts were observed after various stimulations. Gene organization is similar to mammals and birds, and a high degree of conservation of chromosome synteny exists between them. Systematic genomics search against Takifugu rubripes genome supports our conclusions. The T. nigroviridis IL-15 precursor with 172aa (amino acids) contains a putative 53aa signal peptide, while the mature peptide has a calculated molecular mass of 13.36 kDa and a theoretical pI of 4.67. The protein sequence shares 13.3-62.1% identity with reported IL-15s. Phylogenetic analysis grouped Tetraodon with other fish on a separated branch, excluded from mammalian and avian IL-15s. In addition, our analysis on another annotated T. nigroviridis IL-15 demonstrated that it may be a paralogue of IL-15. To differentiate it from the known IL-15s, we described it as IL-15x.
authors.affiliation: College of Life Sciences, Zhejiang University, Hangzhou 310012, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Fang
authors.forename: Li-Xin
authors.initials: LX
authors.lastname: Xiang
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Shao
authors.forename: Yi
authors.initials: Y
authors.lastname: Wen
authors.forename: Shu-Yun
authors.initials: SY
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002415:Cats; D002417:Cattle; D003001:Cloning, Molecular; D023061:Gene Order; D016678:Genome; D006801:Humans; D019409:Interleukin-15 / Q000737:chemistry / Q000145:classification* / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D051381:Rats; D016415:Sequence Alignment; D026801:Synteny; D023721:Tetraodontiformes / Q000235:genetics / Q000276:immunology*
chemical_list: D019409:Interleukin-15