title: Differential regulation of interferon regulatory factor (IRF)-7 and IRF-9 gene expression in the central nervous system during viral infection.
abstract: Interferon regulatory factors (IRFs) are a family of transcription factors involved in the regulation of the interferons (IFNs) and other genes that may have an essential role in antiviral defense in the central nervous system, although this is currently not well defined. Therefore, we examined the regulation of IRF gene expression in the brain during viral infection. Several IRF genes (IRF-2, -3, -5, -7, and -9) were expressed at low levels in the brain of uninfected mice. Following intracranial infection with lymphocytic choriomeningitis virus (LCMV), expression of the IRF-7 and IRF-9 genes increased significantly by day 2. IRF-7 and IRF-9 gene expression in the brain was widespread at sites of LCMV infection, with the highest levels in infiltrating mononuclear cells, microglia/macrophages, and neurons. IRF-7 and IRF-9 gene expression was increased in LCMV-infected brain from IFN-gamma knockout (KO) but not IFN-alpha/betaR KO animals. In the brain, spleen, and liver or cultured glial and spleen cells, IRF-7 but not IRF-9 gene expression increased with delayed kinetics in the absence of STAT1 but not STAT2 following LCMV infection or IFN-alpha treatment, respectively. The stimulation of IRF-7 gene expression by IFN-alpha in glial cell culture was prevented by cycloheximide. Thus, (i) many of the IRF genes were expressed constitutively in the mouse brain; (ii) the IRF-7 and IRF-9 genes were upregulated during viral infection, a process dependent on IFN-alpha/beta but not IFN-gamma; and (iii) IRF-7 but not IRF-9 gene expression can be stimulated in a STAT1-independent but STAT2-dependent fashion via unidentified indirect pathways coupled to the activation of the IFN-alpha/beta receptor.
authors.affiliation: School of Molecular and Microbial Biosciences, G08 Maze Crescent, University of Sydney, New South Wales 2006, Australia.
authors.forename: Shalina S
authors.initials: SS
authors.lastname: Ousman
authors.forename: Jianping
authors.initials: J
authors.lastname: Wang
authors.forename: Iain L
authors.initials: IL
authors.lastname: Campbell
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D050839:Interferon Regulatory Factor-7; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D007372:Interferons / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D008216:Lymphocytic Choriomeningitis / Q000276:immunology* / Q000821:virology; D008217:Lymphocytic choriomeningitis virus / Q000472:pathogenicity*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D017628:Microglia / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D050839:Interferon Regulatory Factor-7; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; C494235:Irf7 protein, mouse; C494228:Isgf3g protein, mouse; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; C494080:Stat1 protein, mouse; C494085:Stat2 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D007372:Interferons