Purchase this article with an account.
Shinsuke Shibata, Dhirendra P Singh, Naoko Shibata, Hiroshi Sasaki, Eri Kubo; Hyperglycemia- and Oxidative Stress-Induced Hyperoxidation of Prdx 6 during Lens Epithelial Cell Damage and Rat Lens Opacity in Vitro and in Vivo. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5723.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
We previously reported that peroxiredoxin 6 (Prdx6), a protein with GSH peroxidase and Ca2+-independent phospholipase A2 (iPLA2) activity, protects human and mouse lens epithelial cells (LECs) from H2O2- and/or hyperglycemia-induced injury and delays lens opacity. In this study, we investigated whether Prdx6 becomes hyperperoxidized after excessive oxidative stress produced by H2O2 or hyperglycemia and whether hyperperoxidation could account for damage to LECs and eye lenses.
The expression of the hyperoxidized form of Prdx6 was analyzed by western blotting and immunohistochemistry, using antibodies against Prdx6-SO3 and Prdx6, in streptozotosine (STZ)-induced diabetic cataract rats as well as in human LECs and rat lenses exposed to variable doses of UVB and H2O2 for different times. The lipid hydroperoxide status of LECs and lenses was monitored with a lipid hydroperoxide (LPO) assay kit. Reactive oxygen species (ROS) levels were quantified by H2DCFH-DA dye, and cell viability by MTS/TUNEL assays. The level of protein oxidation was measured by Oxy blot. The end-products of lipid peroxidation were analyzed immunohistochemically using anti-malondialdehyde (MDA) antibody.
Levels of lipid hydroperoxides, ROS and protein oxidation were time- and dose-dependently increased in H2O2- and glucose-treated LECs, resulting in a reduction in LEC viability and increased apoptosis. The level of Prdx6 hyperoxidation in these cells increased with increasing concentrations of H2O2 (>100 μM) and glucose, and as UVB radiation increased (> 6 KJ/m2), indicating that Prdx6 hyperperoxidation is correlated with H2O2- or glucose-induced toxicity. Hyperoxidized Prdx6 was predominately localized in the nucleus. Diabetic cataract lenses or lenses exposed to oxidative stress showed higher expression of hyperoxidized Prdx6, which was localized to the bow region of organ cultured lenses and STZ-induced diabetic cataractous lenses.
These results provide the first evidence showing that hyperoxidized Prdx6, generated in response to excessive oxidative stress, localizes to the nucleus and induces cell toxicity. Prdx6 may act as marker for increased oxidative stress in LECs and lenses.
This PDF is available to Subscribers Only