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E Kubo, DP Singh, S Shumiya, Y Takamura, Y Akagi; Negative Regulation of LEDGF and Antioxidant Protein (AOP2) and Elevated Expression of TGF-ß During the Progression of Cataract in Shumiya Cataract Rat, a Hereditary Cataract Model . Invest. Ophthalmol. Vis. Sci. 2002;43(13):850.
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Purpose:Shumiya cataract rat (SCR), a hereditary cataract model, develops a cataract at 11 postnatal weeks (Shumiya S., Lab Anim Sci, 1997). Environmental and physiological factors such as UV, H2O2 and biokines, are known to induce cataract. Evidences support the view that the oxidative stress is major factor in inducing cataract and role of antioxidant is predominant to postpone cataract. We reported LEDGF dependent expression of AOP2 and its antioxidant potential in the protection of lens epithelial cells (LECs) (Fatma et al., J. Biol. Chem. 2001) implies that AOP2 may prevent the progression of age-related cataract. We investigated the LEDGF dependent regulation of AOP2 and their expression level as a function in cataractogenesis in SCR. We also studied the correlation of expression of TGF-ß, an inducer of cataractogenesis, and AOP2 in SCR. Methods:Western analysis and semi quantitative RT-PCR were used to assess the protein and mRNA levels of AOP2, LEDGF and TGF--ß in lenses of 11 and 13 week-old SCR. Localization of AOP2 were ascertained with immunohistochemistry using AOP2 specific antibodies. Effect of TGF-ß, and counter effect of AOP2 on LECs were monitored; LECs were cultured with variable concentration TGF-ß in 0.2% of BSA-DMEM for variable time with or without AOP2. Similarly, cells were also exposed to H2O2 to monitor antioxidant potency of AOP2. Live and dead cells assay was done with LIVE/DEAD Viability/Cytotoxicity Kit and DAPI staining was done. Results:Cataractous lenses of 11 and 13 week-old SCR showed the down regulation of AOP2 and LEDGF protein and mRNA levels. Level of AOP2 protein was diminished ∼10 times in cataractous lenses than control ones. Similarly, LEDGF protein was also found at reduced level. In contrast, TGF-ß mRNA and protein levels were elevated significantly. Moreover, Cells over expressing AOP2 could survive under oxidative stress, suggesting its antioxidant property. Conclusion:. Down regulation of AOP2 and up-regulation of TGF-ß may cause the cataract in SCR. Elevated level of AOP2 may be induced by LEDGF and prevent the cell death and the lens opacity against oxidative stress. SCR may be used as model for age-related cataract to understand AOP2's role to postpone cataract and to verify its implication as potential molecule to prevent cataractogenesis.
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