Fig 8.

Early 53BP1 recruitment to DNA damage sites requires PARP1, BAL1, and BBAP. (A) Recruitment of PARP1 and 53BP1 to laser-induced breaks in control or PJ-34-treated cells. Images were obtained at baseline (0) and 10 to 30 min following laser microirradiation. (B) PARP1 and 53BP1 recruitment to laser-induced breaks in control cells or cells depleted of PARP1, BAL1, or BBAP (via siRNA) (20 min following laser microirradiation). (C to F) Kinetics of 53BP1 and γH2AX focus formation following γ-irradiation of control or PJ-34-treated cells (C and D) or control siRNA or BAL1 siRNA-treated cells (E and F). Cells were treated with PJ-34 or vehicle alone (C and D) or control siRNA or BAL1 siRNA (E and F), subjected to low-dose (100-cGy) irradiation, and analyzed for 53BP1 and γH2AX foci at baseline and 1 to 60 min thereafter (C and E). Shown are the percentages of cells with ≥10 foci per nucleus at each time point and condition. Error bars represent the SD of the means for 3 independently stained slides for each time point and condition. At the earliest time points following irradiation (0 to 4 min), the development of repair foci (percentage of cells with ≥10 foci per nucleus) was compared in control and PJ-34-treated cells and control siRNA and BAL siRNA-treated cells with an ANOVA.