Type I IFN-induced expression of Usp25 is dependent on and the synthesis of IRF7 protein.
A, a model of type I IFN-triggered signaling (left). BMDCs were left untreated or treated with IFNα (20 units/ml) or IFNβ (100 ng/ml) in the presence or absence of cycloheximide (CHX) (100 μg/ml) for 12 h followed by qPCR analysis (right graphs). B, Irf3−/−Irf7−/− MEFs were reconstituted with the empty vector (Irf3−/−Irf7−/− + Vector), IRF3 (Irf3−/−Irf7−/− + FLAG-IRF3), or IRF7 (Irf3−/−Irf7−/− + FLAG-IRF7) through lentivirus-mediated gene transfer. Cells were left untreated or treated with IFNα (20 units/ml) for 12 h followed by qPCR analysis. C, MEFs were transfected with control, individual, or combined siRNAs targeting IRF3 or IRF7. Twenty-four hours later, cells were left untreated or treated with IFNα (20 units/ml) for 12 h followed by qPCR analysis. Data shown are representatives of two (A) or at least three independent experiments (B and C). *, p < 0.05; **, p < 0.01; ***, p < 0.001. Error bars represent S.D. Rel., relative.