Abstract
Purpose :
The RPE is a multifunctional epithelial cell providing critical support to the retina and choroid. RPE dysfunction is a feature of age-related ocular diseases such as age-related macular degeneration (AMD), a leading cause of vision loss in the elderly. Studying RPE biology during aging and when stressed are central to identifying potential signaling pathways that may be involved in age-related ocular diseases. Previously, with the development of nuclear receptor atlases of RPE and choroidal endothelial cells, we identified ERRs as candidate receptors of interest that may regulate cell homeostasis, in light of reports that they play a role in lipid and cell metabolism in systemic and neurodegenerative diseases including Alzheimer's disease and atherosclerosis. Herein we set out to identify ERR-based mechanisms in the posterior pole during aging.
Methods :
RNA was extracted from RPE/choroid of mouse eyes (age 1, 12 and 18 months; n≥5/cohort), RPE/choroid of human donors and human primary RPE cultures (n≥4; young cohort: 24-52 yrs old; old cohort: 71-93 yrs old). Expression of ERRs (α, β, and γ) and their target genes (NDUFB5, ACADM and PDK4) were measured by qPCR (n≥3 biological and technical replicates). The metabolic capacity of young versus old RPE, following ERR activation and knockdown, in human primary RPE cell cultures was measured using Seahorse extracellular flux assays. Err expression was evaluated in the laser-induced choroidal neovascularization (CNV) mouse model (n=4/cohort; age 23-28 months). Statistical methods for data analysis included two-tailed Student’s t-test and two-way ANOVA. Values were considered statistically significant at p < 0.05.
Results :
ERRs are expressed in the neural retina, RPE and choroid. The expression of all three ERR isoforms increase with age in mouse and human RPE and choroid. Expression of Errs, its target genes and proliferator-activated receptor gamma coactivator 1-alpha and -beta (Ppargc1a and Ppargc1b) also decrease in the neovascular choroid. Treatment of primary human RPE cells with an ERR-activating ligand increases mitochondrial respiration.
Conclusions :
There is an age-dependent increase in ERR expression in the RPE and choroid, yet a decrease during neovascularization. ERR activation may play a role in regulating energy metabolism. Ongoing studies are exploring the link between ERRs and immune regulation.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.