FIG. 7.

Suppression of FEN1 interferes with efficient repair of oxidative damage in mtDNA. (A) FEN1 was knocked down in HeLa cells by using siRNA. C, controls; Lipo, cells treated with Lipofectamine 2000; Neg., negative control siRNA; F. siRNA, FEN1-specific siRNA. (B and C) DNA damage and repair were assayed by long-range QPCR generating an 8.9-kb product from mtDNA and a 13.5-kb product from the β-globin gene for nuclear DNA. These were normalized to the total DNA in the sample for the nuclear product or a 221-bp PCR product for the mtDNA signal. (B) Damage was induced by various doses of H₂O₂ for 30 min. (C) Repair of mtDNA and nuclear DNA was monitored by QPCR after 30 min of 1.5 mM H₂O₂ treatment. NT, cells not treated with H₂O₂. Results shown are averages of three independent siRNA transfections; error bars represent standard deviations.