Fig. 1

Bioenergetics assessment in MERRF cybrids. A Cell viability was evaluated growing cells for 24 h, 48 h and 72 h in galactose-medium and by performing SRB assay. Data are means ± SEM of four independent experiments (biological replicates). B OCR expressed as pmoles O₂/min, normalized for protein content, under basal conditions and after injection of oligomycin (O), carbonyl cianide 4-(trifluoromethoxy) phenylhydrazone (FCCP; F), rotenone (R) and antimycin A (AA). Data are expressed as means ± SEM of three independent experiments (biological replicates). C Basal, ATP-linked and maximal respiration. All values are means and SEM of three independent experiments (biological replicates). D Western blot of OXPHOS subunits; ACTIN was used as loading control. A representative blot of three independent experiments, analyzing three biological replicates, is shown for each protein. E Densitometry of OXPHOS subunits of three independent experiments (biological replicates). All data are means and SEM and are normalized to control cells. F Western blot of VDAC, TIM23 and TOM20; ACTIN was used as loading control. A representative blot of three independent experiments (biological replicates) is shown for each protein. G Densitometry of VDAC, TIM23 and TOM20 content. All data are means and SEM and are normalized to control cells. H mtDNA content evaluation by qPCR. All values are expressed as means and SEM of three biological replicates and are normalized to control cells. Statistical analyses were performed with ANOVA test (Tukey’s multiple comparisons test). *, ** and *** values significantly different from the control cells, p < 0.05, p < 0.01, p < 0.001 respectively; ^#, ^## and ^### values significantly different from the I-mutant, p < 0.05, p < 0.01, p < 0.001, respectively. Wt-C wild type cybrids, I-C intermediate heteroplasmy cybrids, H-C high heteroplasmy cybrids