Type I-interferon signalling in fish.
Type I interferon (IFN) signalling uses a dual mechanism of action. A Jak-Stat pathway extensively described in mammals involves a cascade of reactions from the interaction of the IFN molecule with its membrane receptor to the stimulation of IFN-induced gene promoters leading in turn to an antiviral state. Regulation of IFN activity is also mediated by two DNA-binding transcription factors called interferon regulatory factor (IRF)-1 and -2, that respectively stimulate and repress the promoter of IFN-induced genes. By gene walking with trout genomic DNA the regulatory sequence of the IRF-1 gene was cloned and sequenced. Sequence analysis showed that this 1 Kb 5' flanking region has a structure which is typical for an IFN-induced gene promoter. It contains a TATA box between -28 to -31, and a NF kappa B site between -41 and -52. No complete interferon stimulatory response element (ISRE) could be found, but ten GAAA motifs, which are characteristic of IFN-induced gene promoters, were found. In rainbow trout gonad (RTG) cells, IRF-1 is expressed constitutively and up-regulated by poly I:C but not by LPS. Transient transfections of RTG cells with a reporter construct based on the luciferase gene show that the IRF1 5' flanking region described above, is sufficient to allow the expression of luciferase and is capable of induction by dsRNA (poly I:C).
Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, U.K.
Bertrand
B
Collet
Christopher J
CJ
Secombes
D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D050856:Interferon Regulatory Factor-1; D050836:Interferon Regulatory Factor-2; D007370:Interferon Type I / Q000235:genetics / Q000502:physiology*; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000235:genetics / Q000502:physiology*; D010750:Phosphoproteins / Q000235:genetics / Q000502:physiology; D011401:Promoter Regions, Genetic; D017471:Receptors, Interferon / Q000502:physiology; D012097:Repressor Proteins; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D016385:TATA Box; D014157:Transcription Factors
D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; C494229:IRF2 protein, human; D050856:Interferon Regulatory Factor-1; D050836:Interferon Regulatory Factor-2; D007370:Interferon Type I; D010750:Phosphoproteins; D017471:Receptors, Interferon; D012097:Repressor Proteins; D014157:Transcription Factors; D008156:Luciferases