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Cody R Fisher, Mara Ebeling, Sandra Rocio Montezuma, Deb A Ferrington; A Mitochondrial Response to Oxidative Stress in RPE from AMD donors. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4892. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Age-related macular degeneration (AMD) is characterized by the death of the retinal pigment epithelium (RPE), likely a result of increased oxidative stress and mitochondrial dysfunction. In the highly oxidative environment of the retina, understanding why damaged mitochondria accumulate in the RPE with AMD is critical. The purpose of this study is to determine if RPE are unable to maintain a healthy population of mitochondria under oxidative stress, leading to the accumulation of mitochondrial damage observed with AMD.
Primary RPE cultures developed from donors without AMD (n=12) and with AMD (n=15) were treated with 300µM hydrogen peroxide for 6 or 24 hours. Genes and proteins involved in mitochondrial biogenesis (AMPK, PGC1α), maintenance (TFAM, VDAC), mitochondrial fusion/fission (FIS1, OPA1), and mitophagy (PINK1, PARKIN) were measured using qPCR and western blots. Data was analyzed using a 2-way ANOVA with Fisher’s LSD post-hoc.
Peroxide treatment induced similar responses in both healthy and AMD RPE. There was a sharp decline in AMPK mRNA at both 6 (p<0.001) and 24 hours (p<0.001), while VDAC (p=0.024) and FIS1 (p=0.002) increased at 6 hours post-peroxide. The active OPA1 (OPA1-L) protein content decreased and the inactive product (OPA1-S) increased after 6 (p=0.04) and 24 hours (p=0.027) peroxide treatment. When comparing disease state, FIS1 mRNA levels are higher in AMD donors relative to No AMD donors (p=0.014). Furthermore, we observed increased AMPK protein in AMD donors (p=0.028).
These results suggest peroxide treatment induces mitochondrial fission while inhibiting mitochondrial fusion and biogenesis. While both No AMD and AMD cells have similar response to peroxide, they differ in their expression of FIS1 and production of AMPK, suggesting possible defects in mitochondrial homeostasis.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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