Modeling aging and retinal degeneration with mitochondrial DNA mutation burden
John Sturgis1,2, Rupesh Singh1, Quinn R Caron1
1Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA.
Aging Cell
|August 30, 2024
Summary
Mitochondrial DNA (mtDNA) mutations accelerate retinal aging and degeneration. This study in a Polg mutator mouse model shows early retinal thinning and functional decline, indicating mtDNA damage contributes to age-related vision loss.
Area of Science:
- Ophthalmology
- Genetics
- Cell Biology
Background:
- Somatic mitochondrial DNA (mtDNA) mutations are linked to retinal degenerative diseases.
- The polymerase gamma (POLG) enzyme is crucial for mtDNA replication and repair.
Purpose of the Study:
- To investigate the impact of aging and accumulated mtDNA mutations on retinal function and structure.
- To utilize the Polg exonuclease-deficient (PolgD257A) mutator mouse model for studying age-related mitochondrial dysfunction.
Main Methods:
- Analysis of retinas from young and aged PolgD257A mutator mice and wild-type controls.
- In vivo and ex vivo assessments including Optical Coherence Tomography (OCT) and Electroretinography (ERG).
- Histological analysis using cell-specific markers and electron microscopy; assessment of oxidative stress and mitophagy markers.
Main Results:
- PolgD257A mice showed decreased retinal and photoreceptor thickness starting at 6 months.
- Significant reduction in ERG responses observed at 6 months in mutant mice.
- Alterations in retinal pigment epithelium (RPE) mitochondrial morphology noted by 3 months; accelerated autofluorescence granule accumulation in D257A RPE.
Conclusions:
- Accumulation of mtDNA mutations impairs mitochondrial function and accelerates retinal aging.
- mtDNA damage is a significant contributor to age-related retinal degeneration.
- The PolgD257A mouse model effectively recapitulates key aspects of age-related retinal dysfunction.
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