Figure 1

Doxycycline inhibits mitochondrial translation. (a) De novo mitochondrial protein synthesis of fibroblasts (Fibs), A549 and A549 ρ° cells treated with vehicle (−) or doxycycline (+). After 5 days of treatment, cultures were pulse-labelled with [³⁵S]-methionine in the presence of emetine. Protein samples were subjected to gel electrophoresis. The gel was stained with Coomassie brilliant blue followed by autoradiography to reveal the labelled mitochondrial translation products, indicated on the left. The migration of protein standards is indicated in the centre. (b) Mean MTCO2 + MTCO3 labelling signals in vehicle (Veh) and doxycycline (DC)-treated cells relative to the mean value of vehicle-treated A549 cells (n = 4). (c) Western blot images of samples from fibroblasts and A549 cells treated with doxycycline over a 5-day period and from untreated A549 ρ° cells. To facilitate quantification, serial dilutions of untreated cells, harvested at t = 0, were also applied. Blots were probed with antibodies against the indicated proteins. Migration of protein standards is indicated on the right. Full-size blots are presented in Supplementary Fig. S11. (d) Mean amounts of the indicated proteins in the treated cells over a 5-day period and of untreated A549 ρ° cells, relative to the amount in the cells at t = 0 (n = 3). Error bars indicate standard deviations. Asterisks denote statistically significant differences (p < 0.05).