Dominant optic atrophy (DOA) arises from mutations in the OPA1 gene that promotes fusion of the inner mitochondrial membrane and plays a role in maintaining ATP levels. Patients display optic disc pallor, retinal ganglion cell (RGC) loss and bilaterally reduced vision. We report a randomized, placebo-controlled trial of idebenone at 2000 mg/kg/day in 56 Opa1 mutant mice (B6;C3-Opa1(Q285STOP)), with RGC dendropathy and visual loss, and 63 wildtype mice. We assessed cellular responses in the retina, brain and liver and RGC morphology, by diolistic labeling, Sholl analysis and quantification of dendritic morphometric features. Vision was assessed by optokinetic responses. ATP levels were raised by 0.57 nmol/mg (97.73%, p=0.035) in brain from idebenone-treated Opa1 mutant mice, but in the liver there was an 80.35% (p=0.011) increase in oxidative damage. NQO1 expression in Opa1 mutant mice was reduced in the brain (to 30.5%, p=0.002) but not in retina, and neither expression level was induced by idebenone. ON-center RGCs failed to show major recovery, other than improvements in secondary dendritic length (by 53.89%, p=0.052) and dendritic territory (by 2.22 × 10(4) μm(2) or 90.24%, p=0.074). An improvement in optokinetic response was observed (by 12.2 ± 3.2s, p=0.003), but this effect was not sustained over time. OFF-center RGCs from idebenone-treated wildtype mice showed shrinkage in total dendritic length by 2.40 mm (48.05%, p=0.025) and a 47.37% diminished Sholl profile (p=0.029). Visual function in wildtype idebenone-treated mice was impaired (2.9 fewer head turns than placebo, p=0.007). Idebenone appears largely ineffective in protecting Opa1 heterozygous RGCs from dendropathy. The detrimental effect of idebenone in wildtype mice has not been previously observed and raises some concerns.
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http://dx.doi.org/10.1016/j.neuroscience.2016.01.042 | DOI Listing |
Cells
January 2025
Jules Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
Dominant optic atrophy (DOA) is the most commonly inherited optic neuropathy. The majority of DOA is caused by mutations in the gene, which encodes a dynamin-related GTPase located to the mitochondrion. OPA1 has been shown to regulate mitochondrial dynamics and promote fusion.
View Article and Find Full Text PDFGenetics
December 2024
Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China.
Metaxins are a family of evolutionarily conserved proteins that reside on the mitochondria outer membrane (MOM) and participate in the protein import into the mitochondria. Metaxin-2 (Mtx2), a member of this family, has been identified as a key component in the machinery for mitochondrial transport in both C. elegans and human neurons.
View Article and Find Full Text PDFCell Death Dis
November 2024
Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
Optic atrophy protein 1 (OPA1) mediates inner mitochondrial membrane (IMM) fusion and cristae organization. Mutations in OPA1 cause autosomal dominant optic atrophy (ADOA), a leading cause of blindness. Cells from ADOA patients show impaired mitochondrial fusion, cristae structure, bioenergetic function, and mitochondrial DNA (mtDNA) integrity.
View Article and Find Full Text PDFSci Rep
October 2024
Institute of Human Genetics, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053, Regensburg, Germany.
Inherited retinal dystrophies (IRDs) and inherited optic neuropathies (IONs) are characterized by distinct genetic causes and molecular mechanisms that can lead to varying degrees of visual impairment. The discovery of pathogenic variants in numerous genes associated with these conditions has deepened our understanding of the molecular pathways that influence both vision and disease manifestation and may ultimately lead to novel therapeutic approaches. Over the past 18 years, our DNA diagnostics unit has been performing genetic testing on patients suspected of having IRD or ION, using state-of-the-art mutation detection technologies that are continuously updated.
View Article and Find Full Text PDFElife
August 2024
Brain Research Institute, Niigata University, Niigata, Japan.
Autosomal dominant optic atrophy (DOA) is a progressive form of blindness caused by degeneration of retinal ganglion cells and their axons, mainly caused by mutations in the OPA1 mitochondrial dynamin GTPase () gene. encodes a dynamin-like GTPase present in the mitochondrial inner membrane. When associated with OPA1 mutations, DOA can present not only ocular symptoms but also multi-organ symptoms (DOA plus).
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