Figure 4.

Intercalators preferentially affect Pol I transcription. (A) HCC116 p53^−/− cells were treated with drug for 30 min or left untreated as indicated. The following concentrations were used: Actinomycin D (ActD): 3 µM; ethidium bromide (EB): 40 µM; proflavine (Pro): 2 µM; CX5461: 5 µM 1 mM 5EU was added to cells and incubation was continued for another hour. Cells were fixed and then permeabilized. Nascent RNA (red, middle panel) was detected using Click-IT^® Cell Reaction Buffer Kit (ThermoFisher) supplemented with Cy5 Azide (Sigma-Aldrich). Nucleolar DNA (blue, left panel) was stained with Hoechst 33342. Merged images are shown (right panel). Images were acquired with a Leica TCS SP5 confocal microscope equipped with an × 63 oil-filled objective. (B) Box-and-whisker plots of quantification of 5EU incorporation into nascent RNA per cell obtained from experiment shown in (A). AU stands for arbitrary units. The median values are shown as horizontal lines.