Enoxacin-Mediated DNA Damage Response

For most of the experiments, enoxacin (E3764, Sigma-Aldrich) was dissolved in 100% DMSO and added to the growth medium at the final concentration of 50 µM. Generally, cells were grown in the presence of 50 µM enoxacin for 48 hours, unless stated otherwise. Cells were exposed to 2 or 5 Gy of ionizing radiation with a high-voltage X-ray generator tube (Faxitron X-Ray Corporation). siRNAs for human TARBP2, PACT, TNRC6A, -B and -C, 53BP1, and GFP or non-targeting siRNAs as negative controls, were purchased from Dharmacon (Table S1) and transfected using Lipofectamine® RNAiMAX (Thermo-Fisher) at the final concentration of 20 nM. Cherry-LacR and I-SceI expressing plasmids^{33 (link)} were transfected with Lipofectamine® 2000 (Thermo-Fisher). I-SceI expression in I-HeLa111 was induced by administrating 1 µg ml⁻¹ doxycycline for 24 hours. To induce Trf2 knock-out, Trf2^F/F MEFs^{35 (link)} were incubated with 600 nM 4-hydroxytamoxifen (4OHT) for 48 hours.