Augmented expression of peroxiredoxin VI in rat lung and kidney after birth implies an antioxidative role

A family of proteins with thioredoxin (TRx)-dependent peroxidase activity, referred to as peroxiredoxins (PRx), has been identified in many species. The sixth member of this family, PRxVI, contains only one conserved cysteine residue, while other members contain additional cysteines. We have isolated a cDNA for rat PRxVI and constructed a large scale baculovirus system to produce the recombinant protein. The protein was purified by a simple two-step procedure utilizing ion-exchange and gel-filtration chromatography. The purified PRxVI exhibited a low level of glutathione-dependent peroxidase but not TRx-dependent activity. PRxVI expression was the highest in lung, followed by brain, kidney, heart, testis, etc. as judged by Northern and Western blot analyses using a rabbit antibody to the purified PRxVI. Immunohistochemical analyses showed strong staining in the epithelium of the bronchus and bronchioles in lung and in the epithelial cells of kidney tubules. In addition, Sertoli cells in testis and islet of Langerhans cells in pancreas were strongly stained. The developmental changes of PRxVI expression in lung and kidney were low in the prenatal stage but induced postnatally. Moreover, intraperitoneal administration of chloroform induced PRxVI mRNA in kidney. When the distribution and the induced expression of PRxVI under conditions of oxidative stress are considered, a physiological role of it as an antioxidative enzyme is indicated.