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Jared Iacovelli, Glenn C Rowe, Zoltan Arany, Magali Saint-Geniez; PGC-1 alpha regulates human RPE oxidative metabolism and anti-oxidant capacity. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1740.
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Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly population of industrialized countries. AMD is thought to occur, at least in part, from oxidative damage to the retinal pigment epithelium (RPE). Thus, enhancement of the anti-oxidant response of RPE is an attractive treatment for AMD. The transcriptional co-activator, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC1α), is powerful mediator of mitochondrial biogenesis, oxidative metabolism, and the cellular anti-oxidant response. This study examines the ability of PGC1α to modulate oxidative metabolism of human RPE (ARPE-19) and protect them from oxidative damage.
ARPE-19 were maintained in standard culture conditions. To induce oxidative stress, confluent ARPE-19 were cultured in serum-free media overnight and treated with hydrogen peroxide. Oxidative stress and reactive oxygen species (ROS) were measured by CM-H2DCFDA fluorescence. Cell death was analyzed by LDH release. Gene expression of PGC-1α and selected oxidative metabolism and anti-oxidant enzymes was analyzed by qPCR. PGC-1α expression was increased using adenoviral delivery. Mitochondrial respiration and fatty acid oxidation was monitored using the Seahorse extracellular flux analyzer.
Over-expression of PGC1α in ARPE-19 significantly increased (p<0.01) all phases of mitochondrial respiration and fatty acid oxidation in the presence of palmitate (p<0.05). This increase corresponded with at least a 3-fold increase (p<0.05) in gene expression of oxidative phosphorylation subunits including COX5B, NDUFB5, and ATP5O. Over-expression of PGC1α also induced significant increases (p<0.05) in anti-oxidant gene expression including CAT, GPX1, PRDX3, SOD1, SOD2, and TXN2. Treatment of confluent ARPE-19 with H2O2 increased ROS in a dose- and time-dependent manner. 18-hr treatment of ARPE-19 with 1 mM H2O2 caused 40% cytotoxicity which was dramatically reduced to 10% by PGC1α overexpression.
PGC1α is a powerful regulator of oxidative metabolism and the antioxidant response in human RPE. Modulation of its expression can reduce oxidant mediated cell death and may be a useful tool to reduce oxidative damage to RPE in vivo.
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