title: Expression regulation of zebrafish interferon regulatory factor 9 by promoter analysis.
abstract: We previously showed that a fish interferon (IFN) regulatory factor 9 (IRF9) homologue, crucian carp Carassius auratus IRF9, displays constitutively nuclear localization and involvement in fish IFN-dependent JAK-STAT signaling; however, little is known about the expression regulation of fish IRF9. Here, we characterized the expression of zebrafish IRF9 by promoter analysis. Zebrafish IRF9 gene promoter contained several putative transcription factor binding sites, including one ISRE (IFN-stimulated response element), one GAS (IFN gamma activation sequence) and three GATEs (IFNγ activated transcriptional element, GATE1/2/3). Further sequence analyses revealed that GAS and GATE motifs existed in all promoters of IRF9 from mammals and fishes. Luciferase assays confirmed that zebrafish IRF9 promoter could be activated by zebrafish IFNφs and zebrafish IFNγ2, as well as transcription factors IRF3, IRF7, and combination of IRF9 and STAT2. Treatment of recombinant crucian carp IFN protein or overexpression of zebrafish IFNγ2 both led to significant increase in crucian carp IRF9 mRNA and protein in cultured fish cells. Comparison of IFN-stimulated promoter activity revealed much more significant induction of zebrafish IRF9 by zebrafish IFNγ2 than by zebrafish IFNφs. Mutation analyses showed that the putative GAS and GATE3 contributed to zebrafish IFNγ2-triggered IRF9 expression, whereas the putative ISRE and the other two GATEs were not functional for induction of zebrafish IRF9. These results together indicated that the expression property of IRF9 might be conserved from fish to mammals and that some not yet identified mechanisms could exist in IRF9 gene transcription regulation in response to IFNs.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Department of Bioengineering & Environmental Science, Changsha University, Changsha 410003, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Shi
authors.forename: Yi-Bing
authors.initials: YB
authors.lastname: Zhang
authors.forename: Jian-She
authors.initials: JS
authors.lastname: Zhang
authors.forename: Jian-Fang
authors.initials: JF
authors.lastname: Gui
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002347:Carps / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit / Q000235:genetics* / Q000378:metabolism; D007371:Interferon-gamma / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics; D015027:Zebrafish / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014157:Transcription Factors; D007371:Interferon-gamma
keywords: Expression regulation; GAS; GATE; IFN; IFN stimulated gene; IRF; IRSE; ISG; ISGF3; Interferon regulatory factor 9; Interferon-gamma activated transcriptional element (GATE); Interferon-gamma activation sequence (GAS); Interferon-stimulated response element (ISRE); Jak; Janus kinase; Stat; Zebrafish; interferon; interferon regulatory factor; interferon stimulated response element; interferon-gamma activation sequence; interferon-gamma-activated transcriptional element; interferon-stimulated gene factor 3; signal transducer and activator of transcription