Fig. 4: Nanog-C and CD2 inhibits the activity of Rad51.

a Representative cell images of the comet assay. HeLa cells co-expressing Nanog-C and Rad51 were treated with CPT for 6 h. The cells transfected with mock vectors and the one expressing Nanog-C, respectively, were used as controls. The medium was changed to fresh CPT-free medium and allow cells to grow for additional 6 and 16 h, respectively. b Tail moments from a were calculated. c, d Similar experiments and analysis with a and b were performed to examine the rescue effect of Rad51 on CD2-prevented DSB repair. e HR reporter assay showing the effect of Nanog-C and CD2 on HR-mediated DNA damage repair. HR-Flex cell lines were transfected with the plasmids expressing I-SceI and Nanog fragments, respectively. After 48 h, the number of GFP-positive cells was analyzed by flow cytometry. f HR reporter assay showing C- and CD2-mediated inhibition of Rad51 activity in the HR repair signaling. HR-Flex cell lines were co-transfected with the plasmids expressing I-SceI, Nanog fragments and Rad51, respectively. Similar analysis was performed with e. g MTT assay assessed the cell viability under CPT treatment. 293 cells expressing GFP-tagged Nanog fragments were analysed 12 h after treatment with 1 μM CPT. The data are based on three independent repeats, and presented as mean ± SEM. ****p < 0.0001; ***p < 0.001; **p < 0.01; *p < 0.05 (Student’s t-test).