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PMID:15642323

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Citation

Reddy, VN, Kasahara, E, Hiraoka, M, Lin, LR and Ho, YS (2004) Effects of variation in superoxide dismutases (SOD) on oxidative stress and apoptosis in lens epithelium. Exp. Eye Res. 79:859-68

Abstract

Among the critical antioxidant enzymes that protect the cells against oxidative stress are superoxide dismutases: CuZnSOD (Sod1) and MnSOD (Sod2). The latter is also implicated in apoptosis. To determine the importance of these enzymes in protection against reactive oxygen species (ROS) in the lens, we analysed DNA strand breaks in lens epithelium from transgenic and knockout (Sod1) mice following exposure to H2O2 in organ culture. Since Sod2 knockouts do not survive, comparison was made of lenses of partially-deficient (heterozygote) for Sod2 and the wild-type controls which have twice the enzyme level. Antioxidant potential of Sod2 was also studied in human lens epithelial cells (SRA01/04) in which the enzyme was up- and down-regulated by transfection with plasmids containing sense and antisense human cDNA for MnSOD. DNA strand breaks in the epithelium of Sod1 knockouts and Sod2 heterozygotes were much greater than in the corresponding wild-type or in transgenic mice over-expressing the enzymes when the lenses were exposed to H2O2. The functional role of Sod2 in apoptosis was examined in cultured human lens epithelial cells. Cells with higher enzyme levels were more resistant to the cytotoxic effects of H2O2, O2- and UV-B radiation. Furthermore, Sod2-deficient cells showed dramatic mitochondrial damage, cytochrome C leakage, caspase 3 activation and increased apoptotic cell death when they were challenged with O2-. Thus, mitochondrial enzyme (Sod2) deficiency plays an important role in the initiation of apoptosis in the lens epithelium.

Links

PubMed Online version:10.1016/j.exer.2004.04.005

Keywords

Animals; Apoptosis/physiology; Caspase 3; Caspases/metabolism; Cells, Cultured; DNA Damage; Epithelial Cells/cytology; Epithelial Cells/enzymology; Gene Expression Regulation, Enzymologic/physiology; Hydrogen Peroxide/pharmacology; Lens Capsule, Crystalline/cytology; Lens Capsule, Crystalline/enzymology; Lens Capsule, Crystalline/physiology; Mice; Mice, Knockout; Mice, Transgenic; Oxidative Stress/physiology; Reactive Oxygen Species/metabolism; Superoxide Dismutase/genetics; Superoxide Dismutase/metabolism; Superoxide Dismutase/physiology

Significance

Annotations

Gene product Qualifier GO ID GO term name Evidence Code with/from Aspect Notes Status


See also

References

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