Fig. 4: HspBP1 knockdown results in decreased DSB repair and increased chromosomal instability.

A Immunoblot analysis of HspBP1 from a stable knockdown of HspBP1 using two different shRNAs in U2OS cells. B Control or HspBP1-depleted U2OS cells were either untreated (UT) or treated with 5 Gy of IR. At the indicated time points, cells were harvested for comet tail formation assays under neural conditions. Representative images and quantification of unrepaired DSBs are shown and data are presented as mean ± SD (n = 3), **P < 0.01, two-tailed Student’s t-test. C A schematic diagram of the fluorescence-based assay for measuring levels of HR-mediated DSB repair. D The efficiency of HR repair was measured by FACS analysis in DR-GFP-U2OS cells transfected with indicated combinations of siRNA. Levels of endogenous HspBP1 and BRCA1 were analyzed by western blotting and data are shown as mean ± SD (n = 3). **P < 0.01. ns, not significant, two-tailed Student’s t-test. E Control and HspBP1 knockdown U2OS cells were treated with 2 Gy of IR and chromosome aberrations were measured using metaphase chromosome spreads. Representative images and quantification of chromosome breaks are shown. P values between the indicated samples were calculated using a Mann-Whitney test. ns not significant. F Array CGH profiles of GM00637 cells transfected with control shRNA versus HspBP1 shRNA. Chromosomal regions above or below the dotted line indicate amplifications or deletions of genomic regions, respectively.