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. Author manuscript; available in PMC: 2019 Aug 20.
Published in final edited form as: Free Radic Biol Med. 2018 Jun 5;124:149–162. doi: 10.1016/j.freeradbiomed.2018.05.094

Figure 1. Paraquat-induced mitochondrial DNA damage is inversely related to OGG1 expression.

Figure 1

A549 cells were treated with paraquat for 24 or 48 hr and subjected to formaldehyde fixation prior to immunofluorescence detection of 8-oxoguanine. (A) Graphical representation of the percent change in 8-oxoguanine intensity within the cytoplasm region following 24- and 48-hr treated cells with increasing concentrations of paraquat. Significance was determined using a 1-way ANOVA with a Dunnett’s posttest comparing treatment groups to an untreated control (* p<0.05, ** p<0.01, *** p<0.001, **** P<0.0001). B. Changes in 8-oxoguanine are depicted in sample images (Hoechst33342, overlaid blue; MitoTracker® orange, overlaid orange; 8-oxoG, overlaid red) from cells exposed to increasing concentrations of paraquat in panel B (line = 40 μm). (C/D) A549 cells were treated with 50 ng/mL ethidium bromide for 14 population doublings to generate A549rhoφ cells devoid of functional mitochondrial DNA. A549 and A549rhoφ cells were treated with paraquat for 24 hr, followed by staining for 8-oxoG. (C) Sample images of A549 cells from wells containing untreated cells and cells exposed to 3 mM paraquat for 24 hr (line = 40 μm). (D) Sample images like Panel C, but with A549rhoφ cells (line = 40 μm). (E) A549 cells were incubated with 5% v.v. Ogg1-BacMam for 48 hours prior to treatment with varying concentrations of paraquat for 24 hr. The cells were subjected to formaldehyde fixation for immunofluorescence detection of 8-oxoguanine and the percent change in 8-oxoguanine intensity within the mitochondria of the cells from varying concentrations of paraquat compared to control cells. (F) A549 cells were incubated with 100 nM Ogg1 siRNA containing Dharmafect® in serum-free conditions. Following 48-hr incubation, the medium was replaced to complete culture medium and the A549 cells were treated with varying concentrations of paraquat for 24 hr. The cells were stained and imaged for 8-oxoguanine. The figure represents the percent change in 8-oxoguanine intensity within the mitochondria of paraquat treated cells compared to media control.