Peroxiredoxin 5 is a mammalian thioredoxin peroxidase ubiquitously expressed in tissues. Peroxiredoxin 5 can be intracellularly localized to mitochondria, peroxisomes, the cytosol, and, to a lesser extent, the nucleus. This remarkably wide subcellular distribution compared with the five other mammalian peroxiredoxins prompted us to further investigate the antioxidant protective function of peroxiredoxin 5 in mammalian cells according to its subcellular localization. Chinese hamster ovary cells overexpressing human peroxiredoxin 5 in the cytosol, in mitochondria, or in the nucleus were established by stable transfection. Cells overexpressing peroxiredoxin 5 were exposed for 1 h to low or acute oxidative stress with exogenously added hydrogen peroxide or tert-butylhydroperoxide. Cell protection conferred by peroxiredoxin 5 was evaluated by clonogenicity and lactate dehydrogenase assays. Overexpressing peroxiredoxin 5 in either the cytosolic, mitochondrial, or nuclear compartment significantly reduced cell death, with more effective protection with overexpression of peroxiredoxin 5 in mitochondria, confirming that this organelle is a major target of peroxides. Moreover, we evaluated, with the comet assay, nuclear DNA damage induced by hydrogen peroxide or tert-butylhydroperoxide. Overexpression of peroxiredoxin 5 in the nucleus significantly decreased DNA damage induced by both peroxides. In conclusion, the present study suggests that multiple subcellular targeting of peroxiredoxin 5 in mammalian cells can be implicated in antioxidant protective mechanisms under nonpathological conditions but also during acute oxidative stress caused by peroxides occurring in pathophysio logical situations. (C) 2003 Elsevier Inc. All rights reserved.
