Figure 4.

Altered Mitochondrial Function in Fibroblasts Carrying p.Arg217His

(A and B) Quantification of mitochondrial membrane potential (MMP) with JC-1. (A) Compared with control fibroblasts, fibroblasts from individuals 1 and 4 (cultured under standard conditions) showed no abnormality of the MMP. (B) However, after treatment with 25 μM H₂O₂ for 18 min, the JC-1 signal ratio was higher in the probands’ cells than in control cells (^∗∗p value < 0.005).

(C) Measurement of ATP content in the mitochondrial matrix. ATP-dependent firefly luciferase was fused to a COX8 targeting signal and thereby localized to this compartment after transient overexpression. Cytoplasmically targeted Renilla luciferase was transfected as a control. Compared with control cells, the fibroblasts from the affected individuals showed a decrease in firefly luminescence (^∗∗∗p value < 0.00001). All experiments were performed at least three times.

Error bars represent SEM.