title: Cloning, characterization and expression analysis of two Tetraodon nigroviridis interleukin-16 isoform genes.
abstract: Interleukin-16 (IL-16) is an important pro-inflammatory cytokine that functions as a chemoattractant factor and is well characterized in human and other mammals, but is largely unknown in fish. In the present study, two isoforms of pro-IL-16 homologues were cloned and characterized from pufferfish Tetraodon nigroviridis. The full-length T. nigroviridis pro-IL-16 isoform 1 cDNA exhibits 2453 bp in size including 291 bp 5'UTR (untranslated region), 1704 bp ORF (open reading frame) and 458 bp 3'UTR, while pro-IL-16 isoform 2 cDNA exhibits a 3801 bp ORF and a 458 bp 3'UTR. Bioinformatics analysis demonstrated that the pro-IL-16 isoform 1 with a predicted mass of 60.6 kDa contained two PDZ (postsynaptic density/disc large/zona occludens-1) domains, whereas the 138.2 kDa pro-IL-16 isoform 2 had two additional PDZ domains in its N-terminal extension. RT-PCR results revealed that ,almost in all examined organs and tissues, the mRNA of both pro-IL-16 isoforms can be detected, except in intestine and gill, where the isoform 2 mRNA is absent. The two putative precursor proteins showed 30.0-33.0% identity to various mammalian and avian homologues. This is the first report of such genes in teleostean fish and we hope the molecular characterization of these two pro-IL-16 isoforms will provide insights into the study of both evolution of IL-16 precursor proteins and the immune system as a whole.
authors.affiliation: College of Life Sciences, Zhejiang University, Hangzhou 310012, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wen
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Shao
authors.forename: Li-Xin
authors.initials: LX
authors.lastname: Xiang
authors.forename: Wei
authors.initials: W
authors.lastname: Fang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D019410:Interleukin-16 / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D023721:Tetraodontiformes / Q000235:genetics*; D014018:Tissue Distribution / Q000235:genetics
chemical_list: D019410:Interleukin-16; D020033:Protein Isoforms; D011498:Protein Precursors; C105950:interleukin 16 precursor