Abstract
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 II 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 kappaB (NFkappaB) induced by extracellularly added H2O2 or tumor necrosis factor-alpha 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-alpha by regulating the intracellular concentration of H2O2.
Highlights
Mammalian Peroxiredoxin Isoforms Can Reduce Hydrogen Peroxide Generated in Response to Growth Factors and Tumor Necrosis Factor-␣*
We showed that the mammalian Prx enzymes are capable of reducing H2O2 produced in cells stimulated with growth factors and of inhibiting nuclear factor B (NFB) activation induced by H2O2 or tumor necrosis factor-␣ (TNF-␣), indicating that they function as peroxidases inside cells and possibly serve as components of the signaling cascades by growth factors and TNF-␣ in which H2O2 acts as an intracellular messenger
Peroxidase Activity of Mammalian Prx Proteins—We have previously shown that yeast thioredoxin peroxidase (TPx) reduces peroxides with the use of electrons provided by the Trx system (Trx, Trx Reductase (TR), and NADPH) [5]
Summary
Vol 273, No 11, Issue of March 13, pp. 6297–6302, 1998 Printed in U.S.A. Mammalian Peroxiredoxin Isoforms Can Reduce Hydrogen Peroxide Generated in Response to Growth Factors and Tumor Necrosis Factor-␣*. Were identified without reference to peroxidase activity but rather in association with a variety of diverse cellular functions including proliferation, differentiation, and immune response [12,13,14,15,16,17,18,19,20,21,22,23,24] Whether any of these mammalian Prx proteins possess peroxidase activity and, if so, the identity of the immediate electron donors both remain unknown. We showed that the mammalian Prx enzymes are capable of reducing H2O2 produced in cells stimulated with growth factors and of inhibiting NFB activation induced by H2O2 or tumor necrosis factor-␣ (TNF-␣), indicating that they function as peroxidases inside cells and possibly serve as components of the signaling cascades by growth factors and TNF-␣ in which H2O2 acts as an intracellular messenger
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