FIG. 8.

CBP recruitment is independent of IRF3 binding to muIFN-β. A) Equal amounts of genomic DNA from L929wt330, L929mut90, and L929mut122 noninfected (0 h) or NDV-infected (collected at 6 and 8 after infection) cells were immunoprecipitated with antibodies directed against IRF-3 and YY1. The corresponding immunoprecipitated DNA was amplified with primers specific for the integrated IFN-β promoter. B) Intensity of the band amplified from anti-IRF3-immunoprecipitated DNA corresponding to the integrated wt330, mut90, and mut122 promoters, respectively, 0, 6, and 8 h after NDV infection was quantified using a PhosphorImager. Results correspond to the averages of two independent amplification reactions. C) (Left panel) Zero (−) or 5 μg (+) of total nuclear extracts prepared from NDV-infected L929 cells was incubated with labeled probe 90 or mut90 in the presence of 1.5 μg of unlabeled sonicated poly(dI/dC) and subjected to gel retardation. When indicated, a 50-fold excess of unlabeled probe 32GT or 32 was added to the reaction mixture. (Right panel) Five micrograms (+) of total nuclear extracts prepared from NDV-infected L929 cells was incubated with labeled probe 90, in the absence of poly(dI/dC), and subjected to gel retardation. When indicated, 2 μg of anti-CBP, anti-IRF3, or total rabbit IgG was added to the reaction mixture. Arrows indicate the most retarded complex, behaving as a YY1-DNA binding complex.