Figure 5.

p300 and CBP function redundantly in NER. (A) OSU-2 cells were transfected with 50 nM of either control siRNA, p300 siRNA, CBP siRNA or both p300 and CBP siRNA for 48 h. The expression of p300 and CBP was detected using western blotting. (B) The siRNA transfected OSU-2 cells were UV irradiated at 10 J/m² and further cultured for various time periods. The genomic DNA was isolated and subjected to ISB analysis to detect the amount of CPD with anti-CPD antibody (B). (C) The intensity of each band was quantified by scanning images and processing with Alphaimager-2000 software. The relative percentage of remaining CPD at different time points is an average of three independent repeats. (n = 3, bar: SD). (D) The siRNA transfected OSU-2 cells were UV irradiated at 40 J/m² through a 5 -µm micropore filter and further cultured for 30 min. Cells were fixed, permeabilized and double stained with mouse anti-DDB2 and rabbit anti-CPD antibodies as described in ‘Materials and Methods’ section. The relative intensity of DDB2 focus was calculated by analyzing 100 foci and normalized to that of CPD (n = 100, bar: SD).