Fig. 1: Short-term CR enhances DNA repair by NHEJ.

a NHEJ reporter cassette integrated in ROSA26 locus. GFP gene is interrupted by an intron containing a “killer” exon that disrupts GFP ORF when spliced in. DSBs are induced by I-SceI endonuclease that cuts on both sides of the “killer” exon generating non-compatible DNA ends. The cuts release the killer exon and NHEJ repair restores the functional GFP gene. b Body weight of ad libitum fed mice on precision pellet diet feeding. Mice were fed with at least 50 kcal/day and food pellets were placed on the cage floor. c Body weight of the mice on 40% CR. Mice were fed 8.4 kcal/day. d NHEJ efficiency is enhanced in CR mice. NHEJ efficiency was analyzed 4 weeks after the start of CR in young adult male mice, five mice per group. Primary cells were isolated from skin, lung, kidney, and brain of the mice, and immediately transfected with the plasmids encoding I-SceI enzyme and DsRed. Representative FACS traces are shown in Supplementary Fig. 1a. e–g DNA-PK is elevated in the skin, and SIRT6 is elevated in the brain of CR mice. e Western blot. f, g Quantification of the Western blot in e. Error bars show s.d., n ≥ 3 mice in each group. Significance was calculated using two-tailed t-test. *p < 0.05; ***p < 0.001.