Fig. 1: The m.3243 A > G mtDNA mutation causes mitochondrial dysfunction and oxidative stress.

a PCR-RFLP and ARMS-qPCR were used to quantify the mutation load for patient-derived fibroblasts (n = 3 independent biological samples) and A549 cybrid cells (n = 5 independent biological samples). b–d Cell respiratory capacity was measured using the Seahorse XFe96 extracellular flux analyser in patient fibroblasts (n = 6 culture wells) showing a major decrease in oxygen consumption under all conditions (b, p < 0.0001). Oxygen consumption dependent on ATP production (c, p < 0.0001)—the response to oligomycin—and extracellular acidification rate (ECAR) are plotted (d, p < 0.0001). e, f The expression of respiratory chain proteins and supercomplex assembly in patient fibroblasts were assessed using blue native gel electrophoresis (BNGE, e) and quantified (f, p < 0.0001), showing a major decrease in the assembly of all supercomplexes from the patient-derived cells (n = 3 independent experiments). g, h The mitochondrial membrane potential of fibroblasts was measured using TMRM with confocal microscopy (g) and quantified (h, p < 0.0001), showing a significant decrease in potential in patient-derived cells (n = 5 independent experiments). Scale bar = 50 μm. i ROS production rates of control and patient fibroblasts were measured using the reporters, DHE (p < 0.0001) and MitoSOX (p < 0.0001). Rates of ROS production were significantly increased in patient-derived cells (n = 6 independent biological samples). Source data are provided as a Source Data file. All data were represented as mean ± SD and data were analysed by one-way ANOVA with Tukey’s multiple comparisons test (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001).