PURPOSE: Mutations in the optic atrophy 1 gene (OPA1) have been reported in 
patients with autosomal dominant optic atrophy (ADOA). OPA1 plays important 
roles in mitochondrial dynamics and cell apoptosis. The link between OPA1 
mutations and changes in bioenergetics is still not fully resolved. The aim of 
this study was to investigate the effects of OPA1 mutations on the mitochondrial 
tubular network and bioenergetics.
METHODS: We established lymphoblastoid cell lines from four ADOA families 
harboring different OPA1 mutations, unaffected relatives (internal control cell 
lines), and unrelated normal controls (normal control cell lines). OPA1 splice 
variants and mRNA were analyzed by reverse transcription-PCR and quantitative 
real-time PCR. Protein isoforms were examined by Western blotting. The 
mitochondrial network was visualized by confocal microscopy. Mitochondrial 
bioenergetics were assessed using a Seahorse XF24 flux analyzer. Mitochondrial 
membrane potential and oxidative damage were analyzed by flow cytometry.
RESULTS: OPA1 mutant cell lines showed significant decreases in OPA1 mRNA and 
protein expression, mitochondrial membrane potential, and ATP synthesis. A 
marked deficiency of the long isoform of OPA1 was observed in cells with OPA1 
mutations in the middle domain and GTPase effector domain. Confocal microscopy 
revealed increased mitochondrial fragmentation in OPA1 mutant cells. OPA1 mutant 
cells also displayed reduced oxygen consumption and underwent glycolysis to 
produce ATP. Moreover, OPA1 mutations caused the accumulation of oxidative 
damage.
CONCLUSIONS: Our experiments demonstrated that OPA1 mutations induced 
mitochondrial fragmentation, uncoupled mitochondrial respiration, and elicited 
dysfunctional bioenergetics. However, there were no significant differences 
among the various OPA1 mutations.