Fig. 5.

BH domains are required for Bcl2 suppression of mtAPE1 activity, mtDNA repair and enhancement of mtDNA mutations. a. Expression levels of Bcl2 and APE1 in H1299 cells expressing WT or each Bcl2 deletion mutant were analyzed by Western blot. HEX-labeled 26-mer AP site mimetic oligonucleotides (substrate) were incubated with mitochondrial extract isolated from H1299 cells expressing WT or each Bcl2 deletion mutant. APE1 endonuclease activity (cleavage of substrate) was analyzed by Typhoon 9410 imager system as described in “Methods”. b and c. H1299 cells expressing WT or each of the Bcl2 deletion mutants were treated with 100 μM H₂O₂ (b) and 200 μM NNK (c) for 60 min. Cells were then washed three times and incubated in fresh culture medium for the indicated times. mtDNA damage or mtDNA mutation was analyzed as described in “Methods”. Quantification data are mean ± SD from three independent experiments