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K. G. Shadrach, J. G. Hollyfield, V. L. Bonilha; Age-Related Changes in the Cytoskeleton of the Retinal Pigment Epithelium. Invest. Ophthalmol. Vis. Sci. 2010;51(13):477.
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An intimate interaction between the apical microvilli of the retinal pigment epithelium (RPE) and the outer segments of the retinal photoreceptors is essential for vision. Age-related changes in the retina accompany visual impairment in the elderly. As the RPE ages it displays a number of key changes that are notable at the ultrastructural level. The precise molecular mechanisms underlying these changes are not well understood. In the present study the age-related changes in ezrin and other cytoskeletal proteins present in the RPE apical microvilli were investigated in rats.
The eyes of F344BN 3-4 month old (young adult), 18 month-old (intermediate) and 24-25 month old (aged) rats were analyzed. Fortransmission and scanning electron microscopy eyes were fixed in 2.5% glutaraldehyde. For tissue immunohistology eyes were fixed in 4% paraformaldehyde and processed for cryosectioning. Cryosections were probed with several antibodies specific to proteins previously localized to the RPE apical surface such as ezrin, EBP50, and neuroglycan C.
Electron microscopy revealed a decrease in RPE apical microvilli density of in aged rats. The labeling in cryosections of the RPE apical surface with ezrin and EBP50 was reduced while neuroglycan C staining did not significantly change during aging. In addition, overall ezrin content in RPE lysates were similar in young and old animals.
RPE apical microvilli decreased in density in aging rats. However, total levels of ezrin in RPE lysates did not significantly decrease in aged RPE cells. Additional experiments will analyze the role of posttranslational modifications and protein associations of ezrin during RPE aging.
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