Figure 8. The C-NHEJ defect alone does not cause CG hypomethylation at satellite repeats.

(A and B) CG methylation (percent) at centromeric α-satellite (A) and pericentromeric satellite-2 repeats (B) in mutant cells. The methylation levels were measured by bisulfite sequencing (PCR products were cloned into TA vector and at least 10 clones were sequenced for each condition) at 2 and ≥4 months after the introduction of the mutation. Because the doubling time of the mutant cells was 25–30 hours (Figure 3A), 2 and ≥4 months roughly corresponded to 48–58 and ≥96–116 cell divisions, respectively. Restoration of the methylation levels in the “rescue” clones was evaluated at 6 weeks after the introduction of WT genes. Data are mean ± SEM. Statistical analysis was performed separately for the data obtained at 2 and ≥4 months and the data obtained after 6 weeks of WT restoration. For the former data sets, **P < 0.0007 (Mann-Whitney U test) was considered statistically significant at the 1% level after Bonferroni correction. For the latter data set, **P < 0.0004 (Mann-Whitney U test) was considered statistically significant at the 1% level after Bonferroni correction. The exact P values, which were significant (P < 0.05) before the correction, are shown for reference. See also Supplemental Figure 9.