Fig. 2

PARP1 was identified as BLM promoter-binding protein and negatively regulates BLM expression. A Schematic diagram illustrating the streptavidin-agarose pull-down assay used for pulling down BLM promoter-binding proteins in PC3 cells. B Venn diagram displaying the differential protein sets between BLM_Exp and Con samples. C Secondary MS of PARP1. D, E Fragments of the BLM promoter in luciferase reporter plasmids, which were detected by PCR. F Western blot analysis showing the efficiency of PARP1 knockdown using shRNA in PC3 cells. G Knockdown of PARP1 increased the activity of the pGL4.10-BLM+95 reporter plasmid, whereas overexpression of PARP1 reduced the activity of the same reporter plasmid in 293T cells. H ChIP-qPCR of BLM promoter was performed with PARP1, or control IgG antibody in PC3 cells. I, J BLM mRNA abundance, as well as PARP1 and BLM protein expression, were evaluated in PC3 cells with transient knockdown of PARP1 or overexpression of PARP1. K–M PC3 cells were treated with olaparib (45 μM) for 48 h, BLM promoter activity and mRNA abundance were measured by RT-qPCR and dual luciferase assay, respectively. BLM protein expression was detected by western blot analysis. Shown are the means ± SD from 3 experiments (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, and “ns” indicated no significant difference)