Mammalian peroxiredoxin isoforms can reduce hydrogen peroxide generatedin response to growth factors and tumor necrosis factor-α

Mammalian tissues express three immunologically distinct peroxiredoxin (Prx) proteins (Prx I, II, and III), which are the products of distinct genes. With the use of recombinant proteins Prx I, II, and III, all have now been shown to possess peroxidase activity and to rely on Trx as a source of reducing equivalents for the reduction of H₂O₂. Prx I and H are cytosolic proteins, whereas Prx III is localized in mitochondria. Transient overexpression of Prx I or II in cultured cells showed that they were able to eliminate the intracellular H₂O₂ generated in response to growth factors. Moreover, the activation of nuclear factor κB (NFκB) induced by extracellularly added H₂O₂ or tumor necrosis factor-α was blocked by overproduction of Prx II. These results suggest that, together with glutathione peroxidase and catalase, Prx enzymes likely play an important role in eliminating peroxides generated during metabolism. In addition, Prx I and II might participate in the signaling cascades of growth factors and tumor necrosis factor-α by regulating the intracellular concentration of H₂O₂.