title: Interleukin-17D in Atlantic salmon (Salmo salar): molecular characterization, 3D modelling and promoter analysis.
abstract: IL-17 is a proinflammatory cytokine that plays an important role in the clearance of extracellular bacteria and contributes to the pathology of many autoimmune and allergic conditions. Much work on IL-17 has been done in humans and higher vertebrates while little work has been conducted in lower vertebrates including fish. In this study, we have cloned and characterized the full-length cDNA and genomic sequence of IL-17D from Atlantic salmon. The Atlantic salmon IL-17D (AsIL-17D) cDNA possessed an open reading frame of 621 bp encoding a putative protein of 206 aa with a predicted molecular weight of 23 kDa. The AsIL-17D gene has two exons and one intron showing the same (genome) organisation compared to zebrafish IL-17D. The encoded protein showed 97.6-48.8% identities to other IL-17D homologues, eight conserved cysteine residues were found within this group. Conserved residues believed to be important in receptor binding were also confirmed in salmon IL-17D by homology modelling. Phylogenetic analysis also confirmed the close relationship with other IL-17D homologues. Functional characterization of the 5' flanking region indicated that the region between -1552 and -150 contained sufficient elements for promoter activity. Tissue expression studies by real-time PCR showed a predominant expression of IL-17D transcript in gonads, skin, intestine, thymus of Atlantic salmon. The involvement of IL-17D during proinflammatory responses was demonstrated by investigating the time-dependent expression profile of IL-17D in head kidney and spleen following intraperitoneal injection of live Aeromonas salmonicida, LPS, and beta-glucan. This study provides further evidence for the existence of distinct homologue of IL-17D isoform in fish showing early expression induced by immunostimulants and bacterial infection that supports the fact that IL-17D is regulated by inflammatory processes in fish.
authors.affiliation: Department of Marine Biotechnology, Norwegian College of Fishery Science, University of Tromsø, N-9037 Tromsø, Norway. jaya.kumari@uit.no
authors.forename: Jaya
authors.initials: J
authors.lastname: Kumari
authors.forename: Atle Noralf
authors.initials: AN
authors.lastname: Larsen
authors.forename: Jarl
authors.initials: J
authors.lastname: Bogwald
authors.forename: Roy A
authors.initials: RA
authors.lastname: Dalmo
mesh_terms: D048409:Aeromonas salmonicida / Q000254:growth & development; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D020224:Expressed Sequence Tags; D020381:Interleukin-17 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D019105:Random Amplified Polymorphic DNA Technique / Q000662:veterinary; D020317:Salmo salar / Q000235:genetics / Q000276:immunology*; D016415:Sequence Alignment
chemical_list: D020381:Interleukin-17; D012333:RNA, Messenger