Fig. 5

NADP⁺ suppresses the PARylation-dependent early DNA damage response. a Doxycycline-induced NADK suppresses the recruitment of the PARylation-dependent DNA damage response. Twenty-four hours after induction, the recruitment kinetics of XRCC1, CHFR, PNKP, NBS1, BARD1, and LIG4 were examined with live cell imaging. The relative intensity on the laser stripes were quantified and summarized at the right panel (mean ± SD, from 15 cells at each time point in each experiment). The highest intensity on the laser stripes was calculated as 100% in each cell, and the kinetics of the recruitment were plotted. Three independent experiments were performed. Bars: 10 μM. b High level of NADP⁺ impairs DNA damage repair. The cells were treated with methyl methanesulfonate (10 mM, 30 min). The kinetics of double-strand break and single-strand break repair was examined by neutral and alkaline comet assays, respectively. Representative comet tails at different time points are shown. The tail moments were summarized from at least 50 cells at each time point in each experiment, and three independent experiments were performed. NT non-treated. **p < 0.01. Data were analyzed using two-tailed unpaired Student’s t tests