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Lookup NU author(s): Dr Kathryn White, Dr Vanessa Hogan, Dr Philip Nichols, Emeritus Professor Doug Turnbull
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PURPOSE. To examine retinal ganglion cell (RGC) and axonal abnormalities in an ENU-induced mutant mouse carrying a protein-truncating nonsense mutation in OPA1. Mutations in the OPA1 gene cause autosomal dominant optic atrophy (ADOA) in which loss of RGCs followed by myelin degeneration in the optic nerve leads to progressive decrease in visual acuity. METHODS. Ultrastructure of the optic nerve was examined in heterozygous mutants and wild-type littermate controls at 6, 9, and 24 months using electron microscopy. The RGC layer was examined at 6 and 24 months. RESULTS. There was an increase in the number of autophagosomes in the RGC layer in heterozygous mutants compared with wild type at 24 months. Signs of optic nerve degeneration were seen as early as 9 months in Opa1(+/-) mice, with more severe degeneration by 24 months. By 24 months, degeneration of axons was also seen in control mice. Numbers of opaque mitochondria in the Opa1(+/-) mice increased at 6 and 24 months, possibly representing an increase in the density of cristae to fulfill the energy requirements of the axon. In addition, mitochondria with vesiculation of the inner membranes, similar to the mutant mitochondria described in a mouse model of Charcot-Marie-Tooth type 2A, were observed. CONCLUSIONS. Mutations in OPA1 cause pathologic changes to optic nerve axons that are similar to, but occur earlier than, age-related degeneration. Increased autophagy is likely to result from an increase in abnormal mitochondria and could be one mechanism contributing to RGC loss and subsequent optic atrophy seen in ADOA. (Invest Ophthalmol Vis Sci. 2009; 50: 2567-2571) DOI:10.1167/iovs.08-2913
Author(s): White KE, Davies VJ, Hogan VE, Piechota MJ, Nichols PP, Turnbull DM, Votruba M
Publication type: Article
Publication status: Published
Journal: Investigative Ophthalmology & Visual Science
Year: 2009
Volume: 50
Issue: 6
Pages: 2567-2571
ISSN (print): 0146-0404
ISSN (electronic): 1552-5783
Publisher: Association for Research in Vision and Ophthalmology
URL: http://dx.doi.org/10.1167/iovs.08-2913
DOI: 10.1167/iovs.08-2913
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