Figure 2.

BRCA1/BCLAF1 Mediates Resistance to DNA Damage and Is Required for Efficient DNA Repair and Maintenance of Genomic Stability

(A and B) Clonogenic survival assays demonstrating that depletion of BRCA1 or BCLAF1 (two independent siRNAs) induces sensitivity to ionizing radiation (IR) and etoposide in (MCF7) cells. Mean surviving fraction of three independent experiments is plotted ± SEM.

(C) Representative immunofluorescent staining of γ-H2AX marked DNA damage in untreated 293T cells depleted of either BRCA1 or BCLAF1 and 1 and 24 hr following 2Gy IR.

(D) Quantification of three independent experiments described above (≥200 cells were scored/experiment). Mean fraction of cells containing ≥5 γ-H2AX foci is plotted ± SEM. Significant differences in the fraction of cells containing ≥5 γ-H2AX foci were assessed using Student’s two-tailed t test and are indicated by ^∗∗∗p < 0.001.

(E) Representative metaphase spreads of control (siCtrl) and BRCA1- or BCLAF1-depleted 293T cells either untreated or 24 hr following 2Gy IR. FISH-mediated whole chromosome painting (chromosome 1, green; chromosome 2, red) was used to identify complex chromosome aberrations.

(F) Quantification of total chromosome aberrations in control, BRCA1, and BCLAF1 depleted 293T and MCF7 cells 24 hr after mock irradiation or irradiation with 2 Gy IR. Graphs represent the mean number of chromosome aberrations/metaphase from three independent experiments ± SEM (≥200 metaphases scored/experiment). See also Figure S2.