FIG 6.

ISG20 expression activates transcriptional pathways involving IRF3. (A) MEFs expressing eGFP, ISG20, and ExoII were induced and transfected with the luciferase driven by the IFN-β promoter (pβLUX) or the IRF3 responsive elements (PRDI/III) or the NF-κB element of the IFN-β promoter (PRDII) along with a SV40 promoter-driven Renilla plasmid. Firefly luciferase RLUs were normalized to Renilla RLUs, and induction data are given as percentages of untreated GFP cell results. (B) MEFs expressing GFP, ISG20, and ExoII mutant were induced and treated at 24 h with siIrf3 or siRNA scramble for an additional 48 h. Selected genes were assessed by qRT-PCR, and induction levels are given as fold changes from sham-treated GFP control results. (C) IFN levels were measured in the tet-off MEF cell culture supernatant before and after poly(I·C) lipid transfection. *, P < 0.05; **, P < 0.01; ***, P < 0.001. (A and C) ANOVA with Dunnett’s post hoc analysis (n = 6, 2 independent experiments). (B) Mann-Whitney test (n = 6, 2 independent experiments).