Alterations in the lenticular protein profile in experimental selenite-induced cataractogenesis and prevention by ellagic acid

Background Accumulating evidence suggests that oxidative stress underlies age-related formation of cataract, and that antioxidants retard cataractogenesis. This study aimed to evaluate whether ellagic acid, a natural polyphenol with antioxidant properties, prevents alterations in the lenticular protein profile in an experimental model of selenite cataract. Methods Alterations in lenticular protein were determined by two-dimensional electrophoresis (2DE) and image analysis. Eluted áA-crystallin spots were analyzed by mass spectrometry. Western blot analysis was also performed to confirm the differential expression of certain crystallins and cytoskeletal proteins. Results In cataractous lenses, 2DE and image analysis revealed approximately 45 and 60 prominent spots in soluble and insoluble protein fractions respectively. Analysis of the pI and molecular weight of protein spots revealed differences in the expression of crystallin proteins in soluble and insoluble fractions. Western blot analysis confirmed changes in the expression of áA- and âB1- crystallins in both soluble and insoluble protein fractions, while mass spectrometry confirmed the degradation of áAcrystallin in selenite cataractous lenses. Western blot analysis also confirmed the occurrence of altered expression of certain cytoskeletal proteins in insoluble fractions. However, the lenticular protein profile in lenses from selenite-challenged, ellagic acid-treated rats was essentially similar to that noted in lenses from normal rats. Conclusions The present study confirms the importance of structural and cytoskeletal proteins in the maintenance of lenticular transparency; the results also suggest that ellagic acid prevents lenticular protein alterations induced by selenite in an experimental setting.