Fig. 4.

Inhibition of ATP synthesis impairs HR-associated foci formation in G2 phase cells after IR. (A–C) BRCA1 and RPA foci formation were reduced, and RAD51 foci formation was significantly impaired under low ATP conditions. RPE cells were irradiated with 1 Gy IR. Recruitment of HR factors was analyzed 2 h after IR. To prevent the progression of S phase cells into the G2 phase during analysis, 3 μM APH was added immediately after IR. DMSO or 10 μM OM + 20 mM 2DG were added 2 h before IR. ATMi was added 30 min before IR. A boxplot was generated based on the results of a single experiment. Similar results were obtained in two independent experiments. Statistical analyses were performed for a single experiment. ^***P < 0.001. (D–F) Representative images of IR-induced BRCA1, RPA and RAD51 foci in G2 phase RPE cells 2 h after 1 Gy IR. Irradiated RPE cells were fixed and stained with (D) BRCA1 and CENPF (G2 phase markers), (E) RPA and CENPF and (F) RAD51 and CENPF. DNA was stained with DAPI. Scale bar, 10 μm.