Figure 2.

In colon cells, TNF-α lowers mitochondrial ATP production, and depletion of mtDNA (ρ⁰ cells) leads to shortened mitochondrial network. A) Specific ATP synthase activity in HT29 cells treated with TNF-α (6 h; ratio of ATP synthase activity and amount of enzyme; n = 3). *P < 0.05, compared to control (con), Student’s t test. B) ATP levels in colonic HCT116 con treated with TNF-α (1–24 h) normalized to total protein (n = 4). *P < 0.05, compared to con, ANOVA. C) Total DNA from HCT116 con and ρ⁰ cells was amplified by PCR with primers specific for mitochondrial DNA (mtDNA, D-Loop) and nuclear DNA (nDNA, 18S gene), followed by separation on agarose gel. D) In HCT116 con and ρ⁰ cells, specific oligomycin-sensitive ATP synthase activity was assessed [oligomycin-sensitive ATP synthase activity normalized to amount of enzyme (n = 3)]. *P < 0.05, compared to con, Student’s t test. E) Confocal 3-D images of HCT116 con and ρ⁰ cell immunofluorescently stained for mitochondrial protein TOM20 (Alexa Fluor 488; representative image of 3 independent experiments, 35 slices, 0.16 µm per slice, 5-µm grid).