Fig. 1
MRE11 and EXO1 mediate extended nascent strand degradation in HU-treated BRCA1- and BRCA2-deficient cancer cells. a Schematic of the single-molecule DNA fiber tract analysis and representative DNA fiber images of PEO4 and PEO1 cells treated with HU (4 mM) for 120 min. IdU, red; CldU, green. Scale bar, 50 μm. b Size distribution of IdU tract length in BRCA2-deficient U2OS (left) and PEO1 (right) cells in the presence and absence of HU. Cells were transfected with control siRNA or EXO1 siRNA before IdU and CldU labeling. Mirin (50 μM) was added concomitantly with HU treatment, as indicated. Out of 3 repeats; n ≥ 250 tracts scored for each data set. Bars represent the median. Statistics: Mann–Whitney; ****P < 0.0001. c Size distribution of IdU tract length in BRCA1-deficient U2OS (left) and UWB1 (right) cells in the presence and absence of HU. Cells were transfected with control siRNA or EXO1 siRNA before IdU and CldU labeling. Mirin (50 μM) was added concomitantly with HU treatment, as indicated. Out of 2 repeats; n ≥ 250 tracts scored for each data set. Bars represent the median. Statistics: Mann–Whitney; **P < 0.01; ****P < 0.0001
