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From the Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana.
PURPOSE. To measure changes in nuclear gene expression resulting from mitochondrial dysfunction in retinal pigment epithelial cells.
METHODS. ARPE-19 retinal pigment epithelial cells were depleted of their mitochondrial (mt)DNA by passaging in a low concentration of ethidium bromide. Loss of mitochondrial DNA was determined by uridine auxotrophy and quantitative real-time polymerase chain reaction of isolated DNA. Loss of mitochondrial membrane potential was estimated by uptake of JC-1. Changes in nuclear gene expression were determined by quantitative real-time reverse transcriptionpolymerase chain reaction of isolated total RNA from ethidium-bromidetreated and untreated cells. Morphologic and phenotypic changes were determined by phase-contrast microscopy, sensitivity to the oxidant tert-butyl hydroperoxide (tBH), and invasion assay.
RESULTS. ARPE-19 cells became auxotrophic for growth on uridine after eight passages in 50 ng/mL ethidium bromide. Quantitative PCR revealed almost complete loss of mitochondrial DNA (
0 cells). Uptake of JC-1 was reduced in the
0 cells, indicating reduction of mitochondrial membrane potential. Quantitative RT-PCR measured increased expression of genes coding for drusen components, lipid transport, extracellular matrix components, and responses to inflammation in the
0 cells. The
0 cells also exhibited an increased sensitivity to killing by tBH and increased migration and invasion through solubulized basement membranecoated tissue culture inserts.
CONCLUSIONS. ARPE-19 cells respond to loss of mitochondrial function by changes in nuclear gene expression that resemble changes observed in age-related macular degeneration. The results lead to the hypothesis that loss of mitochondrial function with age and resultant changes in nuclear gene expression may explain some of the changes in the macula that are associated with the known clinical manifestations of age-related macular degeneration.
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