Identification of an Atlantic salmon IFN multigene cluster encoding three IFN subtypes with very different expression properties.
A cluster of 11 interferon (IFN) genes were identified in the Atlantic salmon genome linked to the growth hormone 1 gene. The genes encode three different IFN subtypes; IFNa (two genes), IFNb (four genes) and IFNc (five genes), which show 22-32% amino acid sequence identity. Expression of the fish IFNs were studied in head kidney, leukocytes or TO cells after stimulation with the dsRNA poly I:C or the imidazoquinoline S-27609. In mammals, poly I:C induces IFN-beta through the RIG-I/MDA5 or the TLR3 pathway, both of which are dependent on NF-kB. In contrast, S-27609 induces mammalian IFN-alpha in plasmacytoid dendritic cells through the TLR7 pathway independent of NF-kappaB. The presence of an NF-kappaB site in their promoters and their strong up-regulation by poly I:C, suggest that salmon IFNa1/IFNa2 are induced through similar pathways as IFN-beta. In contrast, the apparent lack of NF-kappaB motif in the promoter and the strong upregulation by S-27609 in head kidney and leukocytes, suggest that IFNb genes are induced through a pathway similar to mammalian IFN-alpha. IFNc genes showed expression patterns different from both IFNa and IFNb. Taken together, salmon IFNa and IFNb are not orthologs of mammalian IFN-beta and IFN-alpha, respectively, but appear to utilize similar induction pathways.
Sun
Baojian
B
Department of Marine Biotechnology, Norwegian College of Fishery Science, University of Tromsø, N-9037 Tromsø, Norway.
Robertsen
Børre
B
Wang
Zhiqiang
Z
Liu
Bin
B
D000595:Amino Acid Sequence; D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002478:Cells, Cultured; D005091:Exons; D015870:Gene Expression / Q000235:genetics / Q000276:immunology; D007372:Interferons / Q000235:genetics* / Q000276:immunology; D007962:Leukocytes / Q000276:immunology; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000276:immunology*; D010802:Phylogeny; D011070:Poly I-C / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000276:immunology / Q000378:metabolism; D020317:Salmo salar / Q000235:genetics / Q000276:immunology*; D016415:Sequence Alignment; D051196:Toll-Like Receptor 3 / Q000276:immunology / Q000378:metabolism; D051199:Toll-Like Receptor 7 / Q000276:immunology / Q000378:metabolism; D000097782:NF-kappaB-Inducing Kinase
D000634:Aminoquinolines; D007372:Interferons; D011070:Poly I-C; D017346:Protein Serine-Threonine Kinases; D051196:Toll-Like Receptor 3; D051199:Toll-Like Receptor 7; D000097782:NF-kappaB-Inducing Kinase; C095471:4-amino-alpha,alpha,2-trimethyl-1H-imidazo(4,5-c)quinoline-1-ethanol