FIGURE 4.

Effect of LIG3 knockdown on mtDNA repair. A and B, WT and KD cells were treated with either 2 mm MMS (A) or 100 μm H₂O₂ (B) for 30 min at 37 °C in the humidified atmosphere of 5% CO₂. Total cellular DNA was extracted either immediately after the treatment (0 h) or after 6 h of recovery in fresh DMEM (6 h), digested with BamHI, and subjected to QSBA and QSBN. C, frequencies of SSB and DSB induced in mtDNA by MMS and H₂O₂ as measured immediately after treatment (0-h time point). D, % mtDNA degradation as determined by QSBN at the 6-h time point. Error bars, S.E., n = 4. C and D, two-tailed Student's t test assuming unequal variance, WT versus KD. ns, not significant; Mito, mitochondria; **, p < 0.01; ***, p < 0.001.