Abstract
Abstract: :
Purpose: To characterize changes in nuclear gene expression induced by mitochondrial (MT) dysfunction in retinal pigment epithelial cells. Methods: ARPE19 cells were depleted of mitochondrial DNA by passaging cells in 50 nM ethidium bromide. Changes in nuclear gene expression were determined by Northern analysis of cytoplasmic mRNA. Probes for hybridization were obtained by RT-PCR amplification of reverse transcribed cytoplasmic mRNA using primer pairs for approximately 30 selected nuclear genes. Relative hybridization of radiolabeled probes was quantified using phosphor imaging and ImageQuaNT software. Results: ARPE19 cells that had become MT-DNA minus exhibited a decreased growth rate, increased lactic acidosis and an inability to grow in the absence of pyruvate and uridine when compared to untreated controls. Changes in nuclear gene expression included induction of the glucose transporter GLUT1 gene, induction of the stress genes HSF1 and PPARgamma, and a decreased expression of the CAT (catalase) gene. Conclusion: The results indicate that the RPE cell compensates for disruptions in mitochondrial energy metabolism by changes in nuclear gene expression. This approach should be useful in explaining changes in phenotypes brought on by mitochondrial gene dysfunction due to aging or from mutations or deletions in RPE mitochondrial DNA such as those seen in Kearns-Sayre syndrome and some forms of Retinitis Pigmentosa.
Keywords: 417 gene/expression • 567 retinal pigment epithelium • 309 aging