Proteomics Analysis of Cellular Response to Oxidative Stress

TLDR

Peroxiredoxins are enzymes that detoxify peroxides and are regenerated by cellular thiols such as thioredoxin. The study used tandem mass spectrometry to show that oxidative stress weakly oxidizes the active‑site cysteine of peroxiredoxins to cysteic acid, inactivating the enzyme. Proteomic analysis revealed that oxidative stress induces widespread oxidation of peroxiredoxins, producing an acidic, inactivated form that acts as a peroxide sink and whose oxidized/native balance may modulate TNFα‑induced apoptosis in Leydig cells.

Abstract

The proteomics analysis reported here shows that a major cellular response to oxidative stress is the modification of several peroxiredoxins. An acidic form of the peroxiredoxins appeared to be systematically increased under oxidative stress conditions. Peroxiredoxins are enzymes catalyzing the destruction of peroxides. In doing so, a reactive cysteine in the peroxiredoxin active site is weakly oxidized (disulfide or sulfenic acid) by the destroyed peroxides. Cellular thiols (<i>e.g.</i> thioredoxin) are used to regenerate the peroxiredoxins to their active state. Tandem mass spectrometry was carried out to characterize the modified form of the protein produced <i>in vivo</i> by oxidative stress. The cysteine present in the active site was shown to be oxidized into cysteic acid, leading to an inactivated form of peroxiredoxin. This strongly suggested that peroxiredoxins behave as a dam upon oxidative stress, being both important peroxide-destroying enzymes and peroxide targets. Results obtained in a primary culture of Leydig cells challenged with tumor necrosis factor α suggested that this oxidized/native balance of peroxiredoxin 2 may play an active role in resistance or susceptibility to tumor necrosis factor α-induced apoptosis.