Peroxiredoxin V, an atypical thioredoxin peroxidase, is widely expressed in mammalian tissues. In addition, Prdx V is localized in mitochondria, peroxisome, cytosol, and nucleus. Prdx V has been reported to protect a wide range of cellular environments as antioxidant enzyme, and its dysfunctions may be implicated in several diseases, such as cancer, inflammation, and neurodegenerative disease. Identification and relative quantification of proteins affected by Prdx V may help identify novel signaling mechanisms that are important for oxidative stress response. However, the role of Prdx V in the modulation of hypoxia‐related cellular response is not studied yet. In order to examine the function of endogenous Prdx V in hypoxic condition in vivo, we generated a transgenic mouse model with Prdx V siRNA expression controlled by U6 promoter. Of many tissues, the knockdown of Prdx V expression was displayed in kidney, lung, and liver, but not spleen and skin. We conducted on the basis of nano‐UPLC‐MSE proteomic study to identify the Prdx V‐affected protein networks in hypoxic kidneys. In this study, we identified protein networks associated with oxidative stress, fatty acid metabolism, and mitochondrial dysfunction. Our results indicated that Prdx V affected to regulation of kidney homeostasis under hypoxia stress.

Red blood cells (RBCs) have been studied as models for infectious diseases, various symptoms of anemia, hemolysis, and erythrocyte aging. Although do not directly affect RBCs, other diseases may cause RBC physiological alterations that could be advanced for diagnostic aim or to convince better understanding of a certain pathological pattern. In this study, comparative RBC proteomics between healthy and abnormal conditions involve to promote aging related‐biomarker discovery. Peroxiredoxin II (Prdx II; a typical 2‐Cys Prdx) has been originally isolated from erythrocytes, and its structure and peroxidase activity have been adequately studied. Mice absent to Prdx II proteins had heinz bodies in their peripheral blood, and morphologically aged cells were detected in the dense RBC fractions, which contained markedly higher levels of reactive oxygen species (ROS). In addition, a labeling experiment with the thiol‐modifying reagent biotinylated iodoacetamide (BIAM) in Prdx II‒/‒ mice revealed that a variety of RBC proteins were highly oxidized. To identify oxidation‐sensitive proteins in Prdx II‒/‒ mice, we performed RBC comparative proteome analysis by nano‐UPLC‐MSE shotgun proteomics with relative protein quantitative analysis. We found oxidation‐sensitive 18 membrane and 41 cytosol proteins from 32 and 85 peptides containing cysteine oxidation, and analyzed comparative expression pattern in healthy RBCs of Prdx II+/+ mice (W1), healthy RBCs of Prdx II‒/‒ mice (K1), and abnormal RBCs of Prdx II‒/‒ mice (K2). These proteins belonged to cellular functions related with RBC lifespan maintain, such as cytoskeleton, stress‐induced proteins, amino acid/nucleic acid metabolic enzymes, signal transduction, and molecular transporters. Furthermore, protein networks among identified oxidation sensitive proteins were analyzed to associate with aging consequence. Consequently, we expected that RBC proteome may provide clues to understand redox‐imbalanced diseases.

Peroxiredoxin II (Prdx II; a typical 2‐Cys Prdx) has been originally isolated from erythrocytes, and its structure and peroxidase activity have been adequately studied. Mice absent to Prdx II proteins had heinz bodies in their peripheral blood, and morphologically abnormal cells were detected in the dense red blood cell (RBC) fractions, which contained markedly higher levels of reactive oxygen species (ROS). In this study, a labeling experiment with the thiol‐modifying reagent biotinylated iodoacetamide (BIAM) in Prdx I‒/‒ mice revealed that a variety of RBC proteins were highly oxidized. To identify oxidation‐sensitive proteins in Prdx II‒/‒ mice, we performed RBC comparative proteome analysis in membrane and cytosolic fractions by nano‐UPLC‐MSE shotgun proteomics. We found oxidation‐sensitive 54 proteins from 61 peptides containing cysteine oxidation, and analyzed comparative expression pattern in healthy RBCs of Prdx II+/+ mice, healthy RBCs of Prdx II‒/‒ mice, and abnormal RBCs of Prdx II‒/‒ mice. These proteins belonged to cellular functions related with RBC lifespan maintain, such as cytoskeleton, stress‐induced proteins, metabolic enzymes, signal transduction, and transporters. Furthermore, protein networks among identified oxidation sensitive proteins were analyzed to associate with various diseases. Consequently, we expected that RBC proteome may provide clues to understand redox‐imbalanced diseases.

(‐)‐Epigallocatechin 3‐gallate (EGCG) is a potent antioxidant polyphenol in green tea that acts as an anticancer agent via both direct and indirect pathways. Although the relationship between EGCG’s anticancer effects and its antioxidant activity is not fully understood, it is known that EGCG stimulates production of reactive oxygen species (ROS), which induce oxidative stress leading to cell death. In IM9 multiple myeloma cells, EGCG acted in a dose‐ and time‐dependent manner to induce apoptotic cell death. Among the antioxidant enzymes expressed in IM9 cells, levels of peroxiredoxin (Prdx) V were selectively and significantly reduced by EGCG. Moreover, the ROS scavenger NAC completely inhibited EGCG‐induced apoptosis and PrdxV reduction, while overexpression of PrdxV, but not a PrdxVC48S mutant, protected IM9 cells from EGCG‐induced apoptosis. EGCG‐induced reductions in cell viability and PrdxV levels were also observed in primary CD138+ multiple myeloma cells from patients. These results suggest that PrdxV is a key target via which EGCG mediates its anticancer effects.