Fig. 6.

IRF1 is required for the induction of Mda5 in macrophages. a In vivo binding of IRF1 to the Mda5 promoter was analyzed by ChIP assays. Macrophages were treated for 3 h with IFN-α or LPS (n = 4). b BMDMs were transfected with either an siRNA directed against Irf1 or a control siRNA against GFP. Twenty-four hours after transfection, the cells were stimulated for 3 h with IFN-α or LPS and Irf1 expression was determined by qPCR (n = 4). c BMDMs transfected with siRNA against Irf1 or GFP were treated for 3 h with IFN-α or LPS before Mda5 expression was determined by RT-PCR (n = 4). d Similar experiment to that in (c), but using electroporated poly(I:C) as the activator (n = 4). e RAW 264.7 macrophage cell line transfected with siRNA against Irf1 or GFP were treated for 3 h with IFN-α or LPS before Mda5 expression was determined by RT-PCR (n = 4). f Schematic representation of the induction of Mda5 by LPS or IFN-α. Each experiment was performed in triplicate, and the results are shown as the mean ± SD. **p < 0.01, ***p < 0.001, and p < 0.0001 in relation to each stimulated sample compared to controls in each experiment. Data were analyzed using the unpaired Student's t test.