Identification and characterization of TLR8 and MyD88 homologs in Atlantic salmon (Salmo salar).
Toll-like receptor 8 (TLR 8) belongs to a subgroup of the TLR family that recognizes nucleic acids and that is involved in the protection against viruses. In mammals, TLR7 and 8 have been characterized as receptors for viral and synthetic single-stranded RNA. Here we describe the cloning of a TLR8 homolog in Atlantic salmon (Salmo salar) and its proximal adaptor protein MyD88. The mRNA expression of SsTLR8 was tissue-restricted and its highest level was detected in the spleen while SsMyD88 was expressed in all of the tested organs. SsTLR8 and SsMyD88 mRNAs were up-regulated in TO cells treated with recombinant IFN alpha1 and IFN gamma. In vivo, the expression of SsTLR8 was not significantly affected following challenge with salmon alphavirus subtype 3 (SAV3). By contrast, infection with SAV3 up-regulated SsMyD88 transcripts on day 7 post-challenge and the expression remained elevated at day 28. The SsMyD88 expression in vivo paralleled type I IFN expression. In vitro stimulation of salmon head kidney leukocytes with CpG ODNs and IFN gamma also up-regulated SsMyD88 mRNA. Furthermore, ectopic expression of SsMyD88 in HEK cells was able to activate a NF-kappaB reporter construct indicating that the cloned salmon molecule was a functional MyD88 homologue.
The Norwegian College of Fishery Science, University of Tromsø, Tromsø, Norway.
Ingrid
I
Skjaeveland
Dimitar B
DB
Iliev
Guro
G
Strandskog
Jorunn B
JB
Jørgensen
D000524:Alphavirus; D018354:Alphavirus Infections / Q000276:immunology / Q000662:veterinary; D000818:Animals; D002460:Cell Line; D005393:Fish Diseases / Q000276:immunology / Q000821:virology; D015870:Gene Expression; D006801:Humans; D007155:Immunologic Factors / Q000494:pharmacology; D016898:Interferon-alpha / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D007962:Leukocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000821:virology; D053594:Myeloid Differentiation Factor 88 / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D016328:NF-kappa B / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D020317:Salmo salar / Q000276:immunology* / Q000821:virology; D051200:Toll-Like Receptor 8 / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection
C408982:CPG-oligonucleotide; D007155:Immunologic Factors; D016898:Interferon-alpha; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D051200:Toll-Like Receptor 8; D007371:Interferon-gamma