Effects of silencing BLAP75 on DNA damage induced by ionizing radiation

Objective: To study the biological effects of BLM-associated protein 75(BLAP75) in ionizing radiation(IR) induced DNA damage response(DDR). Methods: BLAP75 was silenced in cells by RNA interference. Single-cell gel electrophoresis was performed to quantify the DNA breaks. Also siRNA-resistant BLAP75 was expressed in BLAP75-silenced cells to rescue the phenotype. Western blot was used to examine the DDR phosphorylation upon IR. Results: IR induced more DNA breaks in BLAP75-silenced cells than in 293T control cells without siRNA transfection. After expression of BLAP75 in BLAP75-silenced cells, IR induced DNA breaks were similar to 293T control cells. In response to IR, the phosphorylation level of Chk2 was higher in the BLAP75-silenced cells than in the control cells. Conclusion: BLAP75 alleviates IR-induced DNA damage and possibly plays an important role in IR-induced damage response and repair. (authors)