Fig. 5.
Type-I interferon (IFN)-dependent induction of Clr-b is IRF9 dependent. a Primary mouse embryonic fibroblast cells derived from wild-type (WT), Ifnar1−/−,Irf3−/−Irf9−/−,Irf3-/−, and Irf9−/− mice were treated with 103 U/mL IFN-α4 for 24 h and analyzed for Clr-b cell surface expression by flow cytometry. The dotted line represents the secondary reagent alone; solid lines represent untreated cells; shaded histograms represent treated cells. b Mouse embryonic fibroblast cells as in a were transfected with luciferase reporter constructs and analyzed by dual luciferase reporter assay. The graphs show fold luciferase induction relative to Renilla and normalized to the pGL3 empty vector. Significance was determined by a 2-tailed t test on log-transformed values (n = 3–5 experiments). c Mouse embryonic fibroblast cells were transfected with overexpression vectors containing IRF3, IRF7, and/or IRF9 for 24 h and then left untreated or treated with 103 U/mL IFN-α4 for an additional 24 h before analysis of Clr-b expression by flow cytometry. Histograms are gated on GFP+ cells. Dotted lines represent the secondary reagent alone; solid lines represent untreated cells; shaded histograms represents IFN-treated cells. The results are representative of at least 4 independent experiments.