Fig. 4
Assembly of Rad51 at damaged replication forks is compromised in the absence of PARP1 and PARP2. a DNA fibre analysis was performed in the indicated cells after MMS exposure and recovery for the times shown. The number of stalled forks (red-only tracts) was determined as a ratio of all red-labelled replication structures. These values were subsequently normalised to the equivalent ratio in the corresponding non-treated sample. Error bars represent the SEM from at least three independent experiments. Statistical significance from the normalised ratio of stalled forks in parental U2OS cells was determined using a two-tailed Student’s t-test (NS, not significant; * p < 0.05; ** p < 0.01; *** p < 0.001). b The indicated cell lines transfected with control or XRCC1 siRNA were treated with 1 μM EdU (Unt), or with 1 μM EdU and 0.5 mM MMS for 1 h before recovery in fresh media, and Rad51 foci quantified in EdU-positive cells. Times indicated show hours since addition of EdU and MMS. Error bars represent the SEM from three independent experiments. Statistical significance was determined as in a. c U2OS cells transfected with control or XRCC1 siRNA were treated as in b and Rad51 nuclear foci analysed in EdU-positive cells. Cells were fixed 12 h after addition of EdU and MMS. Error bars represent the SEM from three independent experiments. Statistical significance was determined as in a. d U2OS or parp1/2Δ cells, in the presence or absence of 50 μM B02 (Rad51i), were treated as in (3 C) and γ-H2AX foci quantified in EdU-positive cells. Times indicated show hours since addition of EdU and MMS. Error bars represent the SEM from three independent experiments. Statistical significance was determined as in a
