Localization of 28-kDa peroxiredoxin in rat epithelial tissues and its antioxidant properties

Peroxiredoxins are a novel family of antioxidant proteins that specifically prevent enzymes from metal-catalyzed oxidation. The localization of a memb er of the mono-cystein subfamily of peroxiredoxins, the 28-kDa protein, in different rat tissues and its antioxidant properties were investigated. By immunoblotting, the 28-kDa peroxiredoxin was found to be most highly concen trated in olfactory epithelium and present in all tissues tested (skin, lun g, trachea, kidney, womb, and brain). Immunostaining with rabbit polyclonal antibody raised against the 28-kDa peroxiredoxin revealed the particularly high level of the 28-kDa peroxiredoxin immunoreactivity in air-contacting areas (apical regions and mucus Of the olfactory and respiratory epithelium and skin epidermis), which are continually exposed to numerous air-borne r eactive oxygen species. In the apical regions of the olfactory and respirat ory epithelium. the 28kDa-peroxiredoxin immunogold labeling outlined microv illi and cilia and was mainly located in sustentacular cells and in respira tory and goblet cells, as electronmicroscopic analysis revealed. In skin ep idermis, the 28-kDa peroxiredoxin immunoreactivity was confined to the gran ular layer and specifically concentrated in sebaceous glands of hair follic le. In situ hybridization with P-33-labeled antisense RNA probe revealed th e expression of the 28-kDa peroxiredoxin mRNA in tissues with a high level of the 28-kDa peroxiredoxin immunoreactivity. Immunodepletion of the 28-kDa peroxiredoxin profoundry decreased the antioxidant activity of the olfacto ry tissue extract.