title: Differential regulation of Tetraodon nigroviridis Mx gene promoter activity by constitutively-active forms of STAT1, STAT2, and IRF9.
abstract: Induction of interferons (IFNs) produces an innate immune response through activation of the JAK-STAT signaling pathway. Type I IFN signaling activates downstream gene expression through the IFN-stimulated gene factor 3 (ISGF3) complex, while type II IFN (IFN-γ) signaling is mediated through active STAT1 protein. The IFN target gene Mx is involved in the defense against viral infection. However, the mechanism by which Tetraodon (pufferfish) Mx is regulated by IFN signaling has not been identified. In this study, we describe the cloning and expression of Tetraodon STAT1, STAT2, and IFN regulatory factor 9 (IRF9). By combining constitutively-active STAT1 (STAT1-JH1) and STAT2 (STA2-JH1) fusion proteins with IRF9, we demonstrate that a constitutively-active ISGF3 complex increases the transcriptional activity of the Tetraodon Mx promoter via direct binding to two IFN-stimulated response element (ISRE) sites. In addition, a constitutively-active TnIRF9-S2C containing a fusion of the C-terminal region of STAT2 and IRF9 also activated the Mx promoter through binding to the ISRE sites. Furthermore, constitutively-active STAT1-JH1 elevates Mx promoter activity through two IFN gamma-activated sequence (GAS) elements. The Mx promoter is also activated by constitutively-active TnIRF9-S2C and STAT1-JH1 protein, as determined using an in vivo luciferase assay. We conclude that the Tetraodon Mx gene is activated via Type I (IFN-1) and Type II (IFN-γ) signaling. These results provide mechanistic insights into the role of IFN signaling in teleosts, and the in vivo luciferase assay may be suitable as a tool for studying induction and regulation by IFNs in teleost fish.
authors.affiliation: Department of Biochemistry, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan. Electronic address: chcheng@tmu.edu.tw.
authors.forename: Chia-Hsiung
authors.initials: CH
authors.lastname: Cheng
authors.affiliation: Department of Biochemistry, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan.
authors.forename: Chih-Ming
authors.initials: CM
authors.lastname: Chou
authors.affiliation: The Center of Translational Medicine, Taipei Medical University, Taipei 110, Taiwan.
authors.forename: Cheng-Ying
authors.initials: CY
authors.lastname: Chu
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Gen-Der
authors.initials: GD
authors.lastname: Chen
authors.affiliation: Institute of Fisheries Sciences, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Huang-Wei
authors.initials: HW
authors.lastname: Lien
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Pung-Pung
authors.initials: PP
authors.lastname: Hwang
authors.affiliation: Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Mau-Sun
authors.initials: MS
authors.lastname: Chang
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan. Electronic address: cjibc@gate.sinica.edu.tw.
authors.forename: Chang-Jen
authors.initials: CJ
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005786:Gene Expression Regulation / Q000502:physiology*; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D064547:Myxovirus Resistance Proteins / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D050794:STAT1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D050795:STAT2 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D023721:Tetraodontiformes / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D064547:Myxovirus Resistance Proteins; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor
keywords: IRF9; Interferon; Mx; STAT1; STAT2