2-Cys peroxiredoxin function in intracellular signal transduction: therapeutic implications

Peroxiredoxin-2 represses NRAS-mutated melanoma cells invasion by modulating EMT markers

The second most common mutation in melanoma occurs in NRAS oncogene, being a more aggressive disease that has no effective approved treatment. Besides, cellular plasticity limits better outcomes of the advanced and therapy-resistant patients. Peroxiredoxins (PRDXs) control cellular processes through direct hydrogen peroxide oxidation or by redox-relaying processes. Here, we demonstrated that PRDX2 could act as a modulator of multiple EMT markers in NRAS-mutated melanomas. PRDX2 knockdown lead to phenotypic changes towards invasion in human reconstructed skin and the treatment with a PRDX mimetic (gliotoxin), decreased migration in PRDX2-deficient cells. We also confirmed the favorable clinical outcome of patients expressing PRDX2 in a large primary melanoma cohort. This study contributes to our knowledge about genes involved in phenotype switching and opens a new perspective for PRDX2 as a biomarker and target in NRAS-mutated melanomas.

Redox signaling and skeletal muscle adaptation during aerobic exercise

Redox regulation is a fundamental physiological phenomenon related to oxygen-dependent metabolism, and skeletal muscle is mainly regarded as a primary site for oxidative phosphorylation. Several studies have revealed the importance of reactive oxygen and nitrogen species (RONS) in the signaling process relating to muscle adaptation during exercise. To date, improving knowledge of redox signaling in modulating exercise adaptation has been the subject of comprehensive work and scientific inquiry. The primary aim of this review is to elucidate the molecular and biochemical pathways aligned to RONS as activators of skeletal muscle adaptation and to further identify the interconnecting mechanisms controlling redox balance. We also discuss the RONS-mediated pathways during the muscle adaptive process, including mitochondrial biogenesis, muscle remodeling, vascular angiogenesis, neuron regeneration, and the role of exogenous antioxidants.

Consumption of toxic benthic cyanobacteria by two common demersal fish: Growth, antioxidant and liver histopathology responses

Benthic freshwater cyanobacteria have the potential to produce toxins. Compared with more extensively studied plankton species, little is known about the impact of harmful benthic cyanobacteria on aquatic organisms. As demersal fish are usually in direct contact with benthic cyanobacteria, it is important to understand their interactive effects. This study investigated the physio-chemical responses of two demersal fish (Xenocypris davidi and Crucian carp) after exposure to benthic Oscillatoria (producing cylindrospermopsin, 2 × 106 cells/mL) for 7 days. Interestingly, benthic Oscillatoria had less adverse effects on X. davidi than C. carp. The two demersal fish effectively ingested Oscillatoria, but Oscillatoria cell sheathes could not be fully digested in C. carp intestines and led to growth inhibition. Oscillatoria consumption induced oxidative stress and triggered alterations in detoxification enzyme activities in the X. davidi liver. Superoxide dismutase (SOD) and glutathione reductase (GR) activities significantly increased in the C. carp liver, but catalase (CAT) and detoxification enzymes glutathione S-transferase (GST) and glutathione (GSH) activities were insignificantly changed. This suggested that C. carp may have a relatively weak detoxification capacity for toxic Oscillatoria. Oscillatoria ingestion led to more pronounced liver pathological changes in C. carp, including swelling, deformation, and loss of cytoskeleton structure. Simultaneously, fish consumption of Oscillatoria increased extracellular cylindrospermopsin concentration. These results provide valuable insights into the ecological risks associated with benthic cyanobacteria in aquatic ecosystems.

Modeling Melanoma Heterogeneity In Vitro: Redox, Resistance and Pigmentation Profiles

Microenvironment and transcriptional plasticity generate subpopulations within the tumor, and the use of BRAF inhibitors (BRAFis) contributes to the rise and selection of resistant clones. We stochastically isolated subpopulations (C1, C2, and C3) from naïve melanoma and found that the clones demonstrated distinct morphology, phenotypic, and functional profiles: C1 was less proliferative, more migratory and invasive, less sensitive to BRAFis, less dependent on OXPHOS, more sensitive to oxidative stress, and less pigmented; C2 was more proliferative, less migratory and invasive, more sensitive to BRAFis, less sensitive to oxidative stress, and more pigmented; and C3 was less proliferative, more migratory and invasive, less sensitive to BRAFis, more dependent on OXPHOS, more sensitive to oxidative stress, and more pigmented. Hydrogen peroxide plays a central role in oxidative stress and cell signaling, and PRDXs are one of its main consumers. The intrinsically resistant C1 and C3 clones had lower MITF, PGC-1α, and PRDX1 expression, while C1 had higher AXL and decreased pigmentation markers, linking PRDX1 to clonal heterogeneity and resistance. PRDX2 is depleted in acquired BRAFi-resistant cells and acts as a redox sensor. Our results illustrate that decreased pigmentation markers are related to therapy resistance and decreased antioxidant defense.

Cyclin-dependent Kinase 5 and Neurodegenerative Diseases

Neurodegenerative diseases are a group of diseases characterized by the progressive loss of neurons, including Alzheimer's disease, Parkinson's disease, and Amyotrophic lateral sclerosis. These diseases have a high incidence and mortality rate globally, placing a heavy burden on patients and their families. The pathogenesis of neurodegenerative diseases is complex, and there are no effective treatments at present. Cyclin-dependent kinase 5 is a proline-directed serine/threonine protein kinase that is closely related to the development and function of the nervous system. Under physiological conditions, it is involved in regulating the process of neuronal proliferation, differentiation, migration, and synaptic plasticity. Moreover, there is increasing evidence that cyclin-dependent kinase 5 also plays an important role in the pathogenesis of neurodegenerative diseases. In this review, we address the biological characteristics of cyclin-dependent kinase 5 and its role in neurodegenerative diseases. In particular, this review highlights the underlying mechanistic linkages between cyclin-dependent kinase 5 and mitochondrial dysfunction, oxidative stress and neuroinflammation in the context of neurodegeneration. Finally, we also summarize the currently available cyclin-dependent kinase 5 inhibitors and their prospects for the treatment of neurodegenerative diseases. Taken together, a better understanding of the molecular mechanisms of cyclin-dependent kinase 5 involved in neurodegenerative diseases can lead to the development of new strategies for the prevention and treatment of these devastating diseases.

Paracrine Signaling Mediated by the Cytosolic Tryparedoxin Peroxidase of Trypanosoma cruzi

Peroxiredoxins are abundant and ubiquitous proteins that participate in different cellular functions, such as oxidant detoxification, protein folding, and intracellular signaling. Under different cellular conditions, peroxiredoxins can be secreted by different parasites, promoting the induction of immune responses in hosts. In this work, we demonstrated that the cytosolic tryparedoxin peroxidase of Trypanosoma cruzi (cTXNPx) is secreted by epimastigotes and trypomastigotes associated with extracellular vesicles and also as a vesicle-free protein. By confocal microscopy, we show that cTXNPx can enter host cells by an active mechanism both through vesicles and as a recombinant protein. Transcriptomic analysis revealed that cTXNPx induces endoplasmic reticulum stress and interleukin-8 expression in epithelial cells. This analysis also suggested alterations in cholesterol metabolism in cTXNPx-treated cells, which was confirmed by immunofluorescence showing the accumulation of LDL and the induction of LDL receptors in both epithelial cells and macrophages. BrdU incorporation assays and qPCR showed that cTXNPx has a mitogenic, proliferative, and proinflammatory effect on these cells in a dose-dependent manner. Importantly, we also demonstrated that cTXNPx acts as a paracrine virulence factor, increasing the susceptibility to infection in cTXNPx-pretreated epithelial cells by approximately 40%. Although the results presented in this work are from in vitro studies and likely underestimate the complexity of parasite-host interactions, our work suggests a relevant role for this protein in establishing infection.

Negative pressure wound therapy promotes wound healing of diabetic foot ulcers by up-regulating PRDX2 in wound margin tissue

To understand the changes in the peroxiredoxin-2 (PRDX2) expression level in the wound margin tissue (T-PRDX2) of patients with diabetic foot ulcer (DFU) before and after negative pressure wound therapy (NPWT). Additionally, the study aimed to explore the association between PRDX2 expression and the treatment outcome of DFUs to provide a new theoretical basis for revealing the mechanism of NPWT promoting the healing of DFUs. Fifty-six type 2 diabetes patients with foot ulcers undergoing NPWT (the DFU group) and 28 patients with chronic lower limb skin ulcers with normal glucose tolerance undergoing NPWT (the skin ulcer control [SUC] group) were included in the study. T-PRDX2 was detected using Western blotting, and the superoxide dismutase (SOD) activity and the malondialdehyde (MDA) and glutathione (GSH) levels were detected using a biochemical method. In addition, in vitro experiments were conducted to determine the effect of PRDX2 expression on normal human dermal fibroblast (NHDF) proliferation, migration, and apoptosis. Before NPWT, the DFU group exhibited a significantly lower T-PRDX2 expression level compared with the SUC group. After one week of NPWT, the T-PRDX2 expression level, SOD activity, and GSH content in the wound margin tissues of the DFU and SUC groups significantly increased compared with the before NPWT levels. Conversely, the inflammatory indicators (white blood cell, neutrophil percentage, C-reactive protein, and procalcitonin) and MDA content were significantly lower than the before NPWT levels. The expression changes of T-PRDX2 before and after NPWT in the DFU and SUC groups were positively correlated with the 4-week wound healing rate. In vitro experiments demonstrated that PRDX2 could alleviate the oxidative stress in NHDFs, thereby promoting their proliferation and migration, while reducing cell apoptosis. NPWT promotes DFU healing by increasing T-PRDX2, and changes in the T-PRDX2 might be associated with the therapeutic effect of NPWT.

New insights into the roles of peroxiredoxins in cancer

Oxidative stress is one of the hallmarks of cancer. Tumorigenesis and progression are accompanied by elevated reactive oxygen species (ROS) levels and adaptive elevation of antioxidant expression levels. Peroxiredoxins (PRDXs) are among the most important antioxidants and are widely distributed in a variety of cancers. PRDXs are involved in the regulation of a variety of tumor cell phenotypes, such as invasion, migration, epithelial-mesenchymal transition (EMT) and stemness. PRDXs are also associated with tumor cell resistance to cell death, such as apoptosis and ferroptosis. In addition, PRDXs are involved in the transduction of hypoxic signals in the TME and in the regulation of the function of other cellular components of the TME, such as cancer-associated fibroblasts (CAFs), natural killer (NK) cells and macrophages. This implies that PRDXs are promising targets for cancer treatment. Of course, further studies are needed to realize the clinical application of targeting PRDXs. In this review, we highlight the role of PRDXs in cancer, summarizing the basic features of PRDXs, their association with tumorigenesis, their expression and function in cancer, and their relationship with cancer therapeutic resistance.

Peroxiredoxin 2: An Important Element of the Antioxidant Defense of the Erythrocyte

Peroxiredoxin 2 (Prdx2) is the third most abundant erythrocyte protein. It was known previously as calpromotin since its binding to the membrane stimulates the calcium-dependent potassium channel. Prdx2 is present mostly in cytosol in the form of non-covalent dimers but may associate into doughnut-like decamers and other oligomers. Prdx2 reacts rapidly with hydrogen peroxide (k > 10⁷ M^-1 s^-1). It is the main erythrocyte antioxidant that removes hydrogen peroxide formed endogenously by hemoglobin autoxidation. Prdx2 also reduces other peroxides including lipid, urate, amino acid, and protein hydroperoxides and peroxynitrite. Oxidized Prdx2 can be reduced at the expense of thioredoxin but also of other thiols, especially glutathione. Further reactions of Prdx2 with oxidants lead to hyperoxidation (formation of sulfinyl or sulfonyl derivatives of the peroxidative cysteine). The sulfinyl derivative can be reduced by sulfiredoxin. Circadian oscillations in the level of hyperoxidation of erythrocyte Prdx2 were reported. The protein can be subject to post-translational modifications; some of them, such as phosphorylation, nitration, and acetylation, increase its activity. Prdx2 can also act as a chaperone for hemoglobin and erythrocyte membrane proteins, especially during the maturation of erythrocyte precursors. The extent of Prdx2 oxidation is increased in various diseases and can be an index of oxidative stress.

Pathophysiological Impact of the MEK5/ERK5 Pathway in Oxidative Stress

Oxidative stress regulates many physiological and pathological processes. Indeed, a low increase in the basal level of reactive oxygen species (ROS) is essential for various cellular functions, including signal transduction, gene expression, cell survival or death, as well as antioxidant capacity. However, if the amount of generated ROS overcomes the antioxidant capacity, excessive ROS results in cellular dysfunctions as a consequence of damage to cellular components, including DNA, lipids and proteins, and may eventually lead to cell death or carcinogenesis. Both in vitro and in vivo investigations have shown that activation of the mitogen-activated protein kinase kinase 5/extracellular signal-regulated kinase 5 (MEK5/ERK5) pathway is frequently involved in oxidative stress-elicited effects. In particular, accumulating evidence identified a prominent role of this pathway in the anti-oxidative response. In this respect, activation of krüppel-like factor 2/4 and nuclear factor erythroid 2-related factor 2 emerged among the most frequent events in ERK5-mediated response to oxidative stress. This review summarizes what is known about the role of the MEK5/ERK5 pathway in the response to oxidative stress in pathophysiological contexts within the cardiovascular, respiratory, lymphohematopoietic, urinary and central nervous systems. The possible beneficial or detrimental effects exerted by the MEK5/ERK5 pathway in the above systems are also discussed.

Regulation of peroxiredoxin-3 gene expression under basal and hyperglycemic conditions: Key roles for transcription factors Sp1, CREB and NF-κB

Peroxiredoxin-3 (Prx-3), a thioredoxin-dependent peroxidase located exclusively in the mitochondrial matrix, catalyses peroxides/peroxinitrites. Altered levels of Prx-3 is associated with diabetic cardiomyopathy (DCM). However, molecular mechanisms of Prx-3 gene regulation remain partially understood. We undertook a systemic analysis of the Prx-3 gene to identify the key motifs and transcriptional regulatory molecules. Transfection of promoter-reporter constructs in the cultured cells identified -191/+20 bp domain as the core promoter region. Stringent in silico analysis of this core promoter revealed putative binding sites for specificity protein 1 (Sp1), cAMP response element-binding protein (CREB) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Interestingly, while co-transfection of the -191/+20 bp construct with Sp1/CREB plasmid diminished Prx3 promoter-reporter activity, mRNA and protein levels, co-transfection with NF-κB expression plasmid augmented the same. Consistently, inhibition of Sp1/CREB/NF-κB expression reversed the promoter-reporter activity, mRNA and protein levels of Prx-3, thereby confirming their regulatory effects. ChIP assays provided evidence for interactions of Sp1/CREB/NF-κB with the Prx-3 promoter. H9c2 cells treated with high glucose as well as streptozotocin (STZ)-treated diabetic rats showed time-dependent reduction in promoter activity, endogenous transcript and protein levels of Prx-3. Augmentation of Sp1/CREB protein levels and their strong binding with Prx-3 promoter are responsible for diminished Prx-3 levels under hyperglycemia. The activation/increase in the NF-κB expression under hyperglycemia was not sufficient to restore the reduction of endogenous Prx-3 levels owing to its weak binding affinity. Taken together, this study elucidates the previously unknown roles of Sp1/CREB/NF-κB in regulating Prx-3 gene expression under hyperglycemic condition.

The effect of ingestion of red dragon fruit extract on levels of malondialdehyde and superoxide dismutase after strenuous exercise in rats (Rattus norvegicus)

Background: Prolonged activation of skeletal muscles causes a decrease in the production of fatigue. Exercise with strenuous intensity causes an increase in Reactive Oxygen Species (ROS). An increase in free radicals causes oxidative stress resulting in damage to cell function to mitochondrial dysfunction, and fatigue. This study aimed to determine the antioxidant potential of red dragon fruit (RDF) to delay fatigue due to oxidative stress, which improves cell function in mitochondria.

Methods: 25 male rats (Rattus norvegicus) aged three months were divided into five groups: Group K1 was N.A. (No Activity) but drinking and eating; Group K2 performed strenuous exercise without RDF treatment; Groups 3, 4, and 5 (P1, P2 and P3, respectively) performed strenuous exercise and were treated with 75 mg kg ^-1.bw, 150 mg kg ^-1.bw, and 300 mg kg ^-1.bw of RDF extract, respectively. The exercise for the rats involved intense swimming for 20 minutes  a day three time a week for fouweeks.  Malondialdehyde (MDA) dan SOD was measured with the ELISA and histopathology for muscle soleus and lung tissue.

Results: Strenuous exercise followed by RDF extract ingestion was compared for fatigue in terms of duration and time; before (24.55±1.38 minute) and after (95.31±7.82 minute) and led to a significant difference of 39% (p<0.01). The study also compared MDA before and after RDF extract ingestion in the K2 vs. the P1 group (p<0.05). At the same time, P2 differed more significantly (p<0.01). This indicated a spread of free radicals and featured histopathological damage of muscle cells. However, ingestion of RDF extract leads to improvement of soleus muscle cells; thus, repairs cell function, delaying fatigue.

Conclusion: This study confirmed that strenuous exercise, which causes an increase in ROS, intensifies free radicals with RDF extract ingestion and declines oxidative stress, repairing cell function and delaying fatigue.

Characterization of peroxiredoxin from Neocaridina denticulata sinensis and its antioxidant and DNA protection activity analysis

Peroxiredoxin (Prx) is an antioxidant protein that widely exists in various organisms. To further investigate the role of Prx in the antioxidant and immune responses of Neocaridina denticulata sinensis, the full-length cDNA sequence of a Prx gene (Nd-Prx) from N. denticulata sinensis was obtained. The open reading frame (ORF) of Nd-Prx is 597 bp and encodes 198 amino acids. Amino acid similarity alignment showed that Nd-Prx contained a conserved sequence region "FYPLDFTFVCPTEI". qRT-PCR assay showed that Nd-Prx was expressed in all tested tissues and its expression was highest in the ovary. Nd-Prx was most highly expressed at 36 h after copper stimulation. Nd-Prx expression levels in hepatopancreas were significantly upregulated after Vibrio parahaemolyticus challenge (P < 0.05). In addition, the recombinant Nd-Prx was prepared and its enzyme activity was most stable at 70 °C with pH of 6.0. The antioxidant activity and DNA protection of recombinant Nd-Prx was also demonstrated. In summary, this study investigated the role of Prx in antioxidant and immune responses of N. denticulata sinensis, which might provide a foundation for further exploring Prx in immune system of crustaceans and for the application in disease control.

Curcuminoids as Modulators of EMT in Invasive Cancers: A Review of Molecular Targets With the Contribution of Malignant Mesothelioma Studies

Curcuminoids, which include natural acyclic diarylheptanoids and the synthetic analogs of curcumin, have considerable potential for fighting against all the characteristics of invasive cancers. The epithelial-to-mesenchymal transition (EMT) is a fundamental process for embryonic morphogenesis, however, the last decade has confirmed it orchestrates many features of cancer invasiveness, such as tumor cell stemness, metabolic rewiring, and drug resistance. A wealth of studies has revealed EMT in cancer is in fact driven by an increasing number of parameters, and thus understanding its complexity has now become a cornerstone for defining future therapeutic strategies dealing with cancer progression and metastasis. A specificity of curcuminoids is their ability to target multiple molecular targets, modulate several signaling pathways, modify tumor microenvironments and enhance the host’s immune response. Although the effects of curcumin on these various parameters have been the subject of many reviews, the role of curcuminoids against EMT in the context of cancer have never been reviewed so far. This review first provides an updated overview of all EMT drivers, including signaling pathways, transcription factors, non-coding RNAs (ncRNAs) and tumor microenvironment components, with a special focus on the most recent findings. Secondly, for each of these drivers the effects of curcumin/curcuminoids on specific molecular targets are analyzed. Finally, we address some common findings observed between data reported in the literature and the results of investigations we conducted on experimental malignant mesothelioma, a model of invasive cancer representing a useful tool for studies on EMT and cancer.

Effects of copper pyrithione (CuPT) on apoptosis, ROS production, and gene expression in hemocytes of white shrimp Litopenaeus vannamei

Copper pyrithione (CuPT) is used globally to prevent biofouling. However, it poses certain risks to aquatic ecosystems. To understand the effects of CuPT on Litopenaeus vannamei after exposure to different concentrations of CuPT (0, 64, and 128 μg/L), the apoptotic cell ratio, production of reactive oxygen species (ROS), and gene expression in the hemocytes were studied at 0, 3, 12, 24, and 48 h. The results revealed that ROS production was induced significantly at 3-48 h only in the 128 μg/L groups. The apoptotic cell ratio was increased significantly at 12 and 24 h in the 64 μg/L groups, and at 3-48 h in the 128 μg/L groups. Meanwhile, CuPT exposure changed gene expression in hemocytes at different levels. In the 64 μg/L groups, the expression of Mn-superoxide dismutase (MnSOD) was induced at 12 h, glutathione peroxidase (GPx) was induced at 24 and 48 h, caspase-3 induced at 24 h, metallothionein (MT) and HSP70 were increased at 3 h. In the 128 μg/L groups, MnSOD was increased at 3 h and then decreased at 12-48 h, GPx was up-regulated at 3, 24 h and then decreased at 48 h, caspase-3 was increased at 24 h, MT was increased at 3-48 h, HSP60 and HSP70 were up-regulated at 3-12 h. These results indicated that CuPT induced ROS production and the expression of caspase-3 in hemocytes, then caused hemocyte apoptosis. Expression levels of MnSOD, GPx, MT, HSP60, and HSP70 were up-regulated to protect the hemocyte against CuPT stress.

Characterization and functional analysis of peroxiredoxin 4 gene in the Neocaridina denticulata sinensis

Peroxiredoxin (Prx) is an antioxidant protein family, which widely exists in organisms and plays an important role in innate immunity. In this study, the full-length cDNA of a Prx gene (NdPrx) was obtained from Neocaridina denticulata sinensis, which contains a 735 bp open reading frame (ORF) and encodes a polypeptide of 244 amino acids. It is inferred that the molecular weight of the encoded amino acid is 27261.20 Da and the theoretical isoelectric point is 6.16. Phylogenetic analysis shows that NdPrx and Prx4 have high homology, so it was named NdPrx4. Multiple alignment analysis showed that the amino acid sequence of NdPrx4 had high homology with Prx4 of other species, and the similarity with Homarus americanus was the highest, 92.86%. Quantitative real-time PCR analysis showed that NdPrx4 was expressed in various tissues of N. denticulata sinensis, and the expression in ovary was the highest. It was speculated that NdPrx4 may be related to maternal immune function. Under the stimulation of Cu²⁺, the expression of NdPrx4 reached the peak at 36 h, and showed a downward trend until 72 h, indicating that NdPrx4 may play an important role in the stress response of N. denticulata sinensis. Then, NdPrx4 was recombinantly expressed in E. coli, and its enzymatic characteristics of rNdPrx4 were detected. The result showed that the activity of rNdPrx4 was the highest at pH 5.0 and 55 °C. It was found that Mn²⁺ and Ca²⁺ can inhibit the activity of rNdPrx4, and Zn²⁺ increases the activity of rNdPrx4.

Comparative Transcriptome Analysis of Two Populations of Dastarcus helophoroides (Fairmaire) under High Temperature Stress

The differentially expressed genes (DEGs), key genes and metabolic pathways of the parasitic beetle, Dastarcus helophoroides (Fairmaire), were compared between the fiftieth commercially reared population and the first natural population to reveal the adaptive mechanism in response to high temperature stress. The high-throughput sequencing technique was employed for transcriptome sequencing of two populations of D. helophoroides. In total, 47,763 non-redundant transcripts with the average length of 989.31 bp and the N50 of 1607 bp were obtained. Under high temperature stress, 1108 DEGs were found in the commercial population; while there were 3946 DEGs in the natural population, which were higher than those in the commercial population (3.56 times). High temperature stress of D. helophoroides promoted the expression of heat shock proteins (HSPs) and metabolism-related genes in both populations, but metabolism synthesis and hydrolysis of natural population was much higher, allowing them to produce more resistant substances (such as HSPs, superoxide dismutase (SOD), peroxiredoxin (Prx), etc.). Therefore, HSPs may play a major role in the high temperature adaptation of a commercial population, while the natural population probably respond to heat stress with more resistant substances (such as HSPs, SOD, Prx, etc.). These results provide a reference to select and domesticate a specific ecotype with stronger adaptability to the high temperature weather in the forest and further improve the efficiency of D. helophoroides as a bio-control factor.

Can thiol-based redox systems be utilized as parts for synthetic biology applications?

OBJECTIVES

Synthetic biology has emerged from molecular biology and engineering approaches and aims to develop novel, biologically-inspired systems for industrial and basic research applications ranging from biocomputing to drug production. Surprisingly, redoxin (thioredoxin, glutaredoxin, peroxiredoxin) and other thiol-based redox systems have not been widely utilized in many of these synthetic biology applications.

METHODS

We reviewed thiol-based redox systems and the development of synthetic biology applications that have used thiol-dependent parts.

RESULTS

The development of circuits to facilitate cytoplasmic disulfide bonding, biocomputing and the treatment of intestinal bowel disease are amongst the applications that have used thiol-based parts. We propose that genetically encoded redox sensors, thiol-based biomaterials and intracellular hydrogen peroxide generators may also be valuable components for synthetic biology applications.

DISCUSSION

Thiol-based systems play multiple roles in cellular redox metabolism, antioxidant defense and signaling and could therefore offer a vast and diverse portfolio of components, parts and devices for synthetic biology applications. However, factors limiting the adoption of redoxin systems for synthetic biology applications include the orthogonality of thiol-based components, limitations in the methods to characterize thiol-based systems and an incomplete understanding of the design principles of these systems.

The effect of ingestion of red dragon fruit extract on levels of malondialdehyde and superoxide dismutase after strenuous exercise in rats ( Rattus norvegicus)

Background: Prolonged activation of skeletal muscles causes a decrease in the production of fatigue. Exercise with strenuous intensity causes an increase in Reactive Oxygen Species (ROS). An increase in free radicals causes oxidative stress resulting in damage to cell function to mitochondrial dysfunction, and fatigue. This study aimed to determine the antioxidant potential of red dragon fruit (RDF) to delay fatigue due to oxidative stress, which improves cell function in mitochondria. Methods: 25 male rats (Rattus norvegicus) aged three months were divided into five groups: Group K1 was N.A. (No Activity) but drinking and eating; Group K2 performed strenuous exercise without RDF treatment; Groups 3, 4, and 5 (P1, P2 and P3, respectively) performed strenuous exercise and were treated with 75 mg kg -1.bw, 150 mg kg -1.bw, and 300 mg kg -1.bw of RDF extract, respectively. The exercise for the rats involved intense swimming for 20 minutes  a day three time a week for fouweeks.  Malondialdehyde (MDA) dan SOD was measured with the ELISA and histopathology for muscle soleus and lung tissue. Results: Strenuous exercise followed by RDF extract ingestion was compared for fatigue in terms of duration and time; before (24.55±1.38 minute) and after (95.31±7.82 minute) and led to a significant difference of 39% (p<0.01). The study also compared MDA before and after RDF extract ingestion in the K2 vs. the P1 group (p<0.05). At the same time, P2 differed more significantly (p<0.01). This indicated a spread of free radicals and featured histopathological damage of muscle cells. However, ingestion of RDF extract leads to improvement of soleus muscle cells; thus, repairs cell function, delaying fatigue. Conclusion: This study confirmed that strenuous exercise, which causes an increase in ROS, intensifies free radicals with RDF extract ingestion and declines oxidative stress, repairing cell function and delaying fatigue.

Hyperoxidation of Peroxiredoxins and Effects on Physiology of Drosophila

The catalytic activity of peroxiredoxins (Prx) is determined by the conserved peroxidatic cysteine (Cys_P), which reacts with peroxides to form sulfenic acid (Cys-SOH). Under conditions of oxidative stress, Cys_P is oxidized to catalytically inactive sulfinic (Cys-SO₂) and sulfonic (Cys-SO₃) forms. The Cys-SO₂ form can be reduced in a reaction catalyzed by sulfiredoxin (Srx). To explore the physiological significance of peroxiredoxin overoxidation, we investigated daily variations in the oxidation state of 2-Cys peroxiredoxins in flies of different ages, or under conditions when the pro-oxidative load is high. We found no statistically significant changes in the 2-Cys Prxs monomer:dimer ratio, which indirectly reflects changes in the Prx catalytic activity. However, we found daily variations in Prx-SO_2/3 that were more pronounced in older flies as well as in flies lacking Srx. Unexpectedly, the srx mutant flies did not exhibit a diminished survivorship under normal or oxidative stress conditions. Moreover, the srx mutant was characterized by a higher physiological activity. In conclusion, catalytically inactive forms of Prx-SO_2/3 serve not only as a marker of cellular oxidative burden, but may also play a role in an adaptive response, leading to a positive effect on the physiology of Drosophila melanogaster.

Targeting Nrf2-Mediated Oxidative Stress Response Signaling Pathways as New Therapeutic Strategy for Pituitary Adenomas

Oxidative stress and oxidative damage are the common pathophysiological characteristics in pituitary adenomas (PAs), which have been confirmed with many omics studies in PA tissues and cell/animal experimental studies. Nuclear factor erythroid 2 p45-related factor 2 (Nrf2), the core of oxidative stress response, is an oxidative stress sensor. Nrf2 is synthesized and regulated by multiple factors, including Keap1, ERK1/2, ERK5, JNK1/2, p38 MAPK, PKC, PI3K/AKT, and ER stress, in the cytoplasm. Under the oxidative stress status, Nrf2 quickly translocates from cytoplasm into the nucleus and binds to antioxidant response element /electrophile responsive element to initiate the expressions of antioxidant genes, phases I and II metabolizing enzymes, phase III detoxifying genes, chaperone/stress response genes, and ubiquitination/proteasomal degradation proteins. Many Nrf2 or Keap1 inhibitors have been reported as potential anticancer agents for different cancers. However, Nrf2 inhibitors have not been studied as potential anticancer agents for PAs. We recommend the emphasis on in-depth studies of Nrf2 signaling and potential therapeutic agents targeting Nrf2 signaling pathways as new therapeutic strategies for PAs. Also, the use of Nrf2 inhibitors targeting Nrf2 signaling in combination with ERK inhibitors plus p38 activators or JNK activators targeting MAPK signaling pathways, or drugs targeting mitochondrial dysfunction pathway might produce better anti-tumor effects on PAs. This perspective article reviews the advances in oxidative stress and Nrf2-mediated oxidative stress response signaling pathways in pituitary tumorigenesis, and the potential of targeting Nrf2 signaling pathways as a new therapeutic strategy for PAs.

Involvement of peroxiredoxin 2 in cumulus expansion and oocyte maturation in mice

Peroxiredoxin 2 (Prdx2), an antioxidant enzyme, is expressed in the ovary during the ovulatory process. The aim of the present study was to examine the physiological role of Prdx2 during ovulation using Prdx2-knockout mice and mouse cumulus-oocyte complex (COC) from WT mice. Two days of treatment of immature mice (21-23 days old) with equine chorionic gonadotrophin and followed by treatment with human chorionic gonadotrophin greatly impaired cumulus expansion and oocyte maturation in Prdx2-knockout but not wild-type mice. Treatment of COCs in culture with conoidin A (50µM), a 2-cys Prdx inhibitor, abolished epiregulin (EPI)-induced cumulus expansion. Conoidin A treatment also inhibited EPI-stimulated signal molecules, including signal transducer and activator of transcription-3, AKT and mitogen-activated protein kinase 1/2. Conoidin A treatment also reduced the gene expression of EPI-stimulated expansion-inducing factors (hyaluronan synthase 2 (Has2), pentraxin 3 (Ptx3), TNF-α induced protein 6 (Tnfaip6) and prostaglandin-endoperoxide synthase 2 (Ptgs2)) and oocyte-derived factors (growth differentiation factor 9 (Gdf9) and bone morphogenetic protein 15 (Bmp15)). Furthermore, conoidin A inhibited EPI-induced oocyte maturation and the activity of connexins 43 and 37. Together, these results demonstrate that Prdx2 plays a role in regulating cumulus expansion and oocyte maturation during the ovulatory process in mice, probably by modulating epidermal growth factor receptor signalling.

An Integrated and Multibiomarker approach to delineate oxidative stress status of Bellamya bengalensis under the interactions of elevated temperature and chlorpyrifos contamination

Synergistic effects of warming on bioconcentration and receptiveness of pollutants are still poorly unravelled in conjunction with cellular and molecular responses. The present study addressed the impact of an environmental relevant dose of chlorpyrifos (organophosphate pesticide), under control (25 °C) and elevated levels of temperature (30 °C, 35 °C) in Bellamya bengalensis, a freshwater gastropod for 60 days across various endpoints. Multiple levels of biomarkers were measured: growth conditions (organ to flesh weight ratio, condition index), oxidative stress status (SOD, CAT, GST, LPO) and DNA damage (Comet assay-3^rd, 30^th and 60^th days only) after acute (24, 48 and 72 h) and long-term exposures (10^th, 20^th, 30^th, 40^th, 50^th and 60^th days). An integrated biomarker response (IBR) strategy was adapted to amalgamate results generated from various biomarkers to assess organism's vulnerability to pesticide pollution and how it may shift with warming climate. Significant changes were observed in growth conditions under longer exposure periods. Acute as well as long-term exposures enhanced the antioxidant and detoxification enzyme activity. DNA damage was extensive under longer exposure to stress howbeit was also significantly escalated under acute severe warming. Antioxidant and detoxification mechanisms fell short in counteracting cellular level damage. The IBR results indicated long-term acclimation of B. bengalensis to elevated temperatures and pesticide contamination lead to an improved tolerance level howbeit, acute stress was more detrimental. This study provided evidence for the efficiency of employing an integrated biomarker approach for B. bengalensis in future bio-monitoring studies.

Peroxiredoxin 3 Has Important Roles on Arsenic Trioxide Induced Apoptosis in Human Acute Promyelocytic Leukemia Cell Line via Hyperoxidation of Mitochondrial Specific Reactive Oxygen Species

NB4 cell, the human acute promyelocytic leukemia (APL) cell line, was treated with various concentrations of arsenic trioxide (ATO) to induce apoptosis, measured by staining with 7-amino-actinomycin D (7-AAD) by flow cytometry. 2', 7'-dichlorodihydro-fluorescein-diacetate (DCF-DA) and MitoSOXTM Red mitochondrial superoxide indicator were used to detect intracellular and mitochondrial reactive oxygen species (ROS). The steady-state level of SO2 (Cysteine sulfinic acid, Cys-SO2H) form for peroxiredoxin 3 (PRX3) was measured by a western blot. To evaluate the effect of sulfiredoxin 1 depletion, NB4 cells were transfected with small interfering RNA and analyzed for their influence on ROS, redox enzymes, and apoptosis. The mitochondrial ROS of NB4 cells significantly increased after ATO treatment. NB4 cell apoptosis after ATO treatment increased in a time-dependent manner. Increased SO2 form and dimeric PRX3 were observed as a hyperoxidation reaction in NB4 cells post-ATO treatment, in concordance with mitochondrial ROS accumulation. Sulfiredoxin 1 expression is downregulated by small interfering RNA transfection, which potentiated mitochondrial ROS generation and cell growth arrest in ATO-treated NB4 cells. Our results indicate that ATO-induced ROS generation in APL cell mitochondria is attributable to PRX3 hyperoxidation as well as dimerized PRX3 accumulation, subsequently triggering apoptosis. The downregulation of sulfiredoxin 1 could amplify apoptosis in ATO-treated APL cells.

PRDX1 is a Tumor Suppressor for Nasopharyngeal Carcinoma by Inhibiting PI3K/AKT/TRAF1 Signaling

Background

Peroxiredoxin 1 (PRDX1) has been identified as a dual regulator of tumorigenesis. However, its expression, clinical significance, and biological function in nasopharyngeal carcinoma (NPC) remain unknown. This study aimed to explore the role and underlying mechanisms of PRDX1 in NPC.

Materials and Methods

The expression of PRDX1 in NPC tissues was evaluated by immunohistochemistry, and the relationships between the expression of PRDX1 and clinical features and prognosis of NPC patients were analyzed. The effects of PRDX1 on NPC cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition (EMT) were examined. A tumor-bearing model of nude mouse was established to verify the function of PRDX1 in vivo.

Results

PRDX1 expression level was negatively associated with recurrence and metastasis of NPC. PRDX1 knockdown promoted NPC cell proliferation, migration, invasion and EMT in vitro, and enhanced tumor growth in vivo, while PRDX1 overexpression had opposite effects. Furthermore, transcriptome analysis showed that PRDX1 inhibited the activation of PI3K/AKT/TRAF1 signaling in NPC cells.

Conclusion

PRDX1 inhibits NPC by inhibiting the activation of PI3K/AKT/TRAF1 signaling. PRDX1 is a tumor suppressor in human NPC and may be a prognostic biomarker for NPC patients.

Peri/Epicellular Thiol Oxidoreductases as Mediators of Extracellular Redox Signaling

Significance: Supracellular redox networks regulating cell-extracellular matrix (ECM) and organ system architecture merge with structural and functional (catalytic or allosteric) properties of disulfide bonds. This review addresses emerging evidence that exported thiol oxidoreductases (TORs), such as thioredoxin, protein disulfide isomerases (PDIs), quiescin sulfhydryl oxidases (QSOX)1, and peroxiredoxins, composing a peri/epicellular (pec)TOR pool, mediate relevant signaling. pecTOR functions depend mainly on kinetic and spatial regulation of thiol-disulfide exchange reactions governed by redox potentials, which are modulated by exported intracellular low-molecular-weight thiols, together conferring signal specificity. Recent Advances: pecTOR redox-modulates several targets including integrins, ECM proteins, surface molecules, and plasma components, although clear-cut documentation of direct effects is lacking in many cases. TOR catalytic pathways, displaying common patterns, culminate in substrate thiol reduction, oxidation, or isomerization. Peroxiredoxins act as redox/peroxide sensors, contrary to PDIs, which are likely substrate-targeted redox modulators. Emerging evidence suggests important pecTOR roles in patho(physio)logical processes, including blood coagulation, vascular remodeling, mechanosensing, endothelial function, immune responses, and inflammation. Critical Issues: Effects of pecPDIs supporting thrombosis/platelet activation have been well documented and reached the clinical arena. Roles of pecPDIA1 in vascular remodeling/mechanosensing are also emerging. Extracellular thioredoxin and pecPDIs redox-regulate immunoinflammation. Routes of TOR externalization remain elusive and appear to involve Golgi-independent routes. pecTORs are particularly accessible drug targets. Future Directions: Further understanding mechanisms of thiol redox reactions and developing assays for assessing pecTOR redox activities remain important research avenues. Also, addressing pecTORs as disease markers and achieving more efficient/specific drugs for pecTOR modulation are major perspectives for diagnostic/therapeutic improvements.

Effects of aerial exposure on oxidative stress, antioxidant and non-specific immune responses of juvenile sea cucumber Apostichopus japonicus under low temperature

Desiccation is a commonly stressful situation experienced by sea cucumber during transportation without/less water. The present study was conducted to investigate the effects of aerial exposure on the survival, oxidative damage, antioxidant capacity, immune-related response and gene expression of Apostichopus japonicus at different low temperatures. After acclimation, sea cucumbers were randomly divided into 3 groups, which were exposed to 5 °C, 10 °C and 15 °C in the closed laboratory condition, respectively. Each group has three parallel replicates. During the experiment, coelomic fluid and respiratory tree of A. japonicus were sampled at the time points of 0, 3, 6, 12, 24 and 48 h post-desiccation for further analysis. The results showed that the survival rates of sea cucumber significantly decreased as time prolonged, and those of 5 °C at 6-48 h of desiccation were significantly higher than 15 °C. Most oxidative damage parameters (e.g., O₂^- production, MDA, LPO and PC contents) significant increased after 6-12 h of desiccation. Antioxidant enzyme activities and T-AOC in coelomic fluid firstly increased and then decreased during aerial exposure, indicating that sea cucumber could adjust antioxidant defense to reduce the concentrations of ROS and MDA as a strategy for protecting organisms from oxidative damage in the early stage (0-6 h) of desiccation. The relative expression levels of Hsp90 and Hsp70 mRNA in respiratory tree of sea cucumber exhibited similar rise-fall trends with antioxidant parameters, while immune enzyme activities of ACP, AKP, LSZ and T-NOS, and gene expression of TLR, Rel and p105 all significantly decreased as time prolonged. Overall, low temperature postponed the process of ROS formation and the depression of antioxidant and non-specific immune responses of sea cucumber within a certain extent, which implied that it might play a positive role in improvement of desiccation tolerance. This study not only contribute to better understand the adaption mechanisms of A. japonicus to desiccation stress, but also provide valuable information for sea cucumber culture and transportation.

Peroxiredoxin 4 attenuates glutamate-induced neuronal cell death through inhibition of endoplasmic reticulum stress

High concentrations of glutamate induce neurotoxicity by eliciting reactive oxygen species (ROS) generation and intracellular Ca²⁺ influx. The disruption of Ca²⁺ homeostasis in the endoplasmic reticulum (ER) evokes ER stress, ultimately resulting in neuronal dysfunction. Additionally, glutamate participates in the development of neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Peroxiredoxins (Prxs) are members of a family of antioxidant enzymes that protect cells from neurotoxic factor-induced apoptosis by scavenging hydrogen peroxide (H₂O₂). Prx4 is located in the ER and controls the redox condition within the ER. The present study investigated the protective effects of Prx4 against glutamate-induced neurotoxicity linked to ER stress. HT22 cells in which Prx4 was either overexpressed or silenced were used to elucidate the protective role of Prx4 against glutamate toxicity. The expression of Prx4 in HT22 cells was significantly increased in response to glutamate treatment, while ROS scavengers and ER chemical chaperones reduced Prx4 levels. Moreover, Prx4 overexpression reduces glutamate-induced apoptosis of HT22 cells by inhibiting ROS formation, Ca²⁺ influx, and ER stress. Therefore, we conclude that Prx4 has protective effects against glutamate-induced HT22 cell damage. Collectively, these results suggest that Prx4 could contribute to the treatment of neuronal disorders.

Immune response to acute heat stress in the intestine of the red swamp crayfish, Procambarus clarkii

High temperature is an important environmental factor that affects the survival and immunity of aquatic animals. The intestine of crustaceans is their first line of defense, and the physiological homeostasis of this organ can be influenced by high temperature stress. The red swamp crayfish Procambarus clarkii is an important commercial aquaculture species in China, but little is known about its intestinal immune response to acute heat stress. In this study, we investigated the intestinal immune response of P. clarkii individuals that were assigned to the control (25 °C) and heat stress (35 °C) groups. Biochemical assays were conducted for the oxidative stress parameters ·O₂^- generation capacity, lipid peroxide content, and malondialdehyde content; the activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase; and the activities of the immunity-related enzymes alkaline phosphatase, acid phosphatase, and lysozyme. The relative expression level of the antioxidant genes heat shock protein 70 (hsp70), ferritin (fer), and metallothione (met) was examined by RT-PCR. Based on the data obtained, all the parameters tended to increase, peak and then decrease with time, and were significantly different between the two groups (P < 0.05). These findings reveal that acute heat stress adversely affects the antioxidant status and immune function in the P. clarkii intestine. They lay the groundwork for future studies on the effect of rising water temperatures on immune function and survival of this species.

Peroxiredoxin 5 deficiency exacerbates iron overload-induced neuronal death via ER-mediated mitochondrial fission in mouse hippocampus

Iron is an essential element for cellular functions, including those of neuronal cells. However, an imbalance of iron homeostasis, such as iron overload, has been observed in several neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease. Iron overload causes neuronal toxicity through mitochondrial fission, dysregulation of Ca²⁺, ER-stress, and ROS production. Nevertheless, the precise mechanisms between iron-induced oxidative stress and iron toxicity related to mitochondria and endoplasmic reticulum (ER) in vivo are not fully understood. Here, we demonstrate the role of peroxiredoxin 5 (Prx5) in iron overload-induced neurotoxicity using Prx5-deficient mice. Iron concentrations and ROS levels in mice fed a high iron diet were significantly higher in Prx5^−/− mice than wildtype (WT) mice. Prx5 deficiency also exacerbated ER-stress and ER-mediated mitochondrial fission via Ca²⁺/calcineurin-mediated dephosphorylation of Drp1 at Serine 637. Moreover, immunoreactive levels of cleaved caspase3 in the CA3 region of the hippocampus were higher in iron-loaded Prx5^−/− mice than WT mice. Furthermore, treatment with N-acetyl-cysteine, a reactive oxygen species (ROS) scavenger, attenuated iron overload-induced hippocampal damage by inhibiting ROS production, ER-stress, and mitochondrial fission in iron-loaded Prx5^−/− mice. Therefore, we suggest that iron overload-induced oxidative stress and ER-mediated mitochondrial fission may be essential for understanding iron-mediated neuronal cell death in the hippocampus and that Prx5 may be useful as a novel therapeutic target in the treatment of iron overload-mediated diseases and neurodegenerative diseases.

Antioxidant Enzymes and Male Fertility: Lessons from Knockout Models

Significance: Spermatozoa are very sensitive to high levels of reactive oxygen species (ROS) due to the limited antioxidant systems present in these terminal cells. However, tight regulation of ROS levels must be ensured to accomplish the unique goal of the spermatozoon, that is, the transfer of the paternal genome into the mature oocyte during the fertilization process. Thus, it is essential that the restricted antioxidant enzymatic systems are active for sperm function. Recent Advances: Oxidative stress is associated with low sperm quality. High levels of ROS in spermatozoa produce oxidation of lipids, proteins, and DNA that lead to lipid peroxidation, oxidation of essential structural proteins and enzymes, and mutations due to oxidation of DNA. Critical Issues: In this study, we described the available knockout mouse models that helped to better understand the role of different antioxidant enzymes in male fertility. We focused mainly on those studies that directly explore the effects of the lack of these enzymes in male fertility and included information when existing knockout mouse models produced for other purposes were used. Special attention was given in this review to the consequences of the absence of antioxidant enzymes on sperm quality and fertility of aging males from the knockout models. Future Directions: Further studies using novel mouse models lacking different antioxidants and their combinations are essential to understand the consequences of high levels of ROS in aging testes, epididymes, spermatozoa, and embryo development to produce a healthy baby.

The overexpression of peroxiredoxin-4 affects the progression of idiopathic pulmonary fibrosis

Background

Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) is life-threatening. Several serum biomarkers, such as Krebs von den Lungen-6 (KL-6) and surfactant protein D (SP-D), are clinically used for evaluating AE-IPF, but these biomarkers are not adequate for establishing an early and accurate diagnosis of AE-IPF. Recently, the protective roles of the members of the peroxiredoxin (PRDX) family have been reported in IPF; however, the role of PRDX4 in AE-IPF is unclear.

Methods

Serum levels of PRDX4 protein, KL-6, SP-D and lactate dehydrogenase (LDH) in 51 patients with stable IPF (S-IPF), 38 patients with AE-IPF and 15 healthy volunteers were retrospectively assessed using enzyme-linked immunosorbent assay. Moreover, as an animal model of pulmonary fibrosis, wild-type (WT) and PRDX4-transgenic (Tg) mice were intratracheally administered with bleomycin (BLM, 2 mg/kg), and fibrotic and inflammatory changes in lungs were evaluated 3 weeks after the intratracheal administration.

Results

Serum levels of PRDX4 protein, KL-6, SP-D and LDH in patients with S-IPF and AE-IPF were significantly higher than those in healthy volunteers, and those in AE-IPF patients were the highest among the three groups. Using receiver operating characteristic curves, area under the curve values of serum PRDX4 protein, KL-6, SP-D, and LDH for detecting AE-IPF were 0.873, 0.698, 0.675, and 0.906, respectively. BLM-treated Tg mice demonstrated aggravated histopathological findings and poor prognosis compared with BLM-treated WT mice. Moreover, PRDX4 expression was observed in alveolar macrophages and lung epithelial cells of BLM-treated Tg mice.

Conclusions

PRDX4 is associated with the aggravation of inflammatory changes and fibrosis in the pathogenesis of IPF, and serum PRDX4 may be useful in clinical practice of IPF patients.

The crystal structure of sulfiredoxin from Arabidopsis thaliana revealed a more robust antioxidant mechanism in plants

Typical 2-cysteine peroxiredoxins (2-Cys Prxs) are critical peroxidase sensors and could be deactivated by the hyperoxidation under oxidative stress. In plants, 2-Cys Prxs present at a high level in chloroplasts and are repaired by Sulfiredoxin. Whereas many studies have explored the mechanism of Sulfiredoxin from Homo sapiens (HsSrx), the molecular mechanism of Sulfiredoxin in plants with unique photosynthesis remains unclear. Here we report the crystal structure of Sulfiredoxin from Arabidopsis thaliana (AtSrx), which displayed a typical ParB/Srx fold with an ATP bound at a conservative nucleotide binding motif GCHR. Both the ADP binding pocket and the putative AtSrx-AtPrxA interaction surface of AtSrx are more positively charged comparing to HsSrx, suggesting a robust mechanism of AtSrx. These features illustrate the unique mechanisms of AtSrx, which are vital for figure out the strategies of plants to cope with oxidation stress.

Waterborne zinc induced lobe-dependent effect on oxidative stress and energy metabolism in hepatopancreas of Larimichthys crocea

The study aimed to compare differences in oxidative stress and energy metabolism between the left and right lobe of hepatopancreas in large yellow croaker Larimichthys crocea exposed to 0 (control), 20, and 100 μM Zn for 96 h. Tipical biomarkers were examined including the proportion of white hepatopancreas, lipid content, malondialdehyde (MDA) level, glutathione (GSH) content, activity levels of enzymes (Cu/Zn-superoxide dismutase, Cu/Zn-SOD; catalase, CAT; glutathione peroxidase, GPx; glutathione reductase, GR; mitochondrial ATP synthase, F-ATPase; malate dehydrogenase, MDH; succinate dehydrogenase, SDH; hepatic lipase, HTGL; lipoprotein lipase, LPL), mRNA levels of genes encoding these enzymes (sod1, cat, gpx1a, gr, atp5b, mdh, sdh, htgl, and lpl), and gene expression of signaling molecules the NF-E2-related nuclear factor 2 (nrf2) and Kelch-like ECH-associated protein 1 (keap1). A whitish color in the left lobe of hepatopancreas was observed in the control and Zn-exposed fish. Contrarily, the right lobe of hepatopancreas tended towards red with increasing Zn levels. The phenomenon was further confirmed by that lipid content was reduced in the right lobe and was not significantly affected in the left lobe by Zn. The right lobe showed higher energy consumption than the left lobe as reflected by the up-regulation of activity levels of HTGL, LPL, F-ATPase, MDH, and SDH. Lipid peroxidation declined by 20 μM Zn and was unchanged by 100 μM Zn in both lobes, which could be explained by increased activity levels of Cu/Zn-SOD and GPx. However, the magnitude of increase in Cu/Zn-SOD activity was greater in the right lobe than that in the left one. The difference in enzyme activity between two lobes may be involved in changes in mRNA levels of sod1, gr, atp5b, sdh, htgl, lpl, and nrf2, which was further confirmed by positive relationships between enzyme activity and gene expression. Our data also showed positive correlations between nrf2 expression and mRNA levels of its target genes, suggesting that Nrf2 was required for the protracted induction of these genes. Our results demonstrated the potential molecular mechanism of Zn-induced differences between lobes of hepatopancreas, suggesting that the sampling part of hepatopancreas should be considered with caution when assessing metal contamination.

Peroxiredoxin 5 Inhibits Glutamate-Induced Neuronal Cell Death through the Regulation of Calcineurin-Dependent Mitochondrial Dynamics in HT22 Cells

Glutamate is an essential neurotransmitter in the central nervous system (CNS). However, high glutamate concentrations can lead to neurodegenerative diseases. A hallmark of glutamate toxicity is high levels of reactive oxygen species (ROS), which can trigger Ca²⁺ influx and dynamin-related protein 1 (Drp1)-mediated mitochondrial fission. Peroxiredoxin 5 (Prx5) is a well-known cysteine-dependent peroxidase enzyme. However, the precise effects of Prx5 on glutamate toxicity are still unclear. In this study, we investigated the role of Prx5 in glutamate-induced neuronal cell death. We found that glutamate treatment induces endogenous Prx5 expression and Ca²⁺/calcineurin-dependent dephosphorylation of Drp1, resulting in mitochondrial fission and neuronal cell death. Our results indicate that Prx5 inhibits glutamate-induced mitochondrial fission through the regulation of Ca²⁺/calcineurin-dependent dephosphorylation of Drp1, and it does so by scavenging cytosolic and mitochondrial ROS. Therefore, we suggest that Ca²⁺/calcineurin-dependent mitochondrial dynamics are deeply associated with glutamate-induced neurotoxicity. Consequently, Prx5 may be used as a potential agent for developing therapies against glutamate-induced neurotoxicity and neurodegenerative diseases where it plays a key role.

Expression of thioredoxin 1 and peroxiredoxins in squamous cervical carcinoma and its predictive role in NACT

Background

This study aims to investigate the expression of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 in bulky cervical squamous carcinoma and its predictive role in cisplatin-based neoadjuvant chemotherapy.

Methods

Initially, the expression of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 protein was analyzed in 13 human cervical squamous cancer tissues and their paired adjacent non-cancerous tissues by western-blotting and immunohistochemistry. Then, correlation between the expression of thioredoxin 1, peroxiredoxin 1, peroxiredoxin 2 and responses to cisplatin-based neoadjuvant chemotherapy was analyzed in 35 paired tumor samples (pre- and post-chemotherapy) from bulky cervical squamous cancer patients by immunohistochemistry.

Results

A clinical response occurred in 48.6% (17/35) of patients, including 14.3% (5/35) with a complete response and 34.3% (12/35) with a partial response. The expression of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 was much higher in cervical squamous cancer tissues compared with paired adjacent non-cancerous tissues by western-blotting and immunohistochemistry. Additionally, the expression of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 was significantly up-regulated in post-chemotherapy tissues compared to pre-chemotherapy cervical cancer tissues. High levels of thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 were associated with a poor chemotherapy response in cervical squamous cancer patients.

Conclusions

Thioredoxin 1, peroxiredoxin 1 and peroxiredoxin 2 are frequently over-expressed in cervical squamous cancer. High expression levels of these proteins were related to a poor response to cisplatin-based neoadjuvant chemotherapy. The present study is the first report that thioredoxin peroxidase system may serve as a prediction of the responses to neoadjuvant chemotherapy in cervical squamous cancer.

Elucidation of the inhibition mechanism of sulfiredoxin using molecular modeling and development of its inhibitors

When intracellular reactive oxygen species (ROS) increase, cancer cells are more vulnerable to oxidative stress compared to normal cells; thus, the collapse of redox homeostasis can lead to selective death of cancer cells. Indeed, recent studies have shown that inhibition of sulfiredoxin (Srx), which participates in antioxidant mechanisms, induces ROS-mediated cancer cell death. In this paper, we describe how an Srx inhibitor, J14 (4-[[[4-[4-(2-chlor-ophenyl)-1-piperazinyl]-6-phenyl-2-pyrimidinyl]thio]methyl]-benzoic acid), interferes with the antioxidant activity of Srx at the molecular level. We searched for possible binding sites of Srx using a binding site prediction method and uncovered two possible inhibition mechanisms of Srx by J14. Using molecular dynamics simulations and binding free energy calculations, we confirmed that J14 binds to the ATP binding site; therefore, J14 acts as a competitive inhibitor of ATP, settling the question of the two mechanisms. Based on the inhibition mechanism revealed at the atomic level, we designed several derivatives of J14, which led to LMT-328 (4-(((4-(4-(2-Chlorophenyl)piperazin-1-yl)-6-(2,4-dihydroxy-5-isopropylphenyl)pyrimidin-2-yl)thio)methyl)benzoic acid), which is possibly an even more potent inhibitor than J14.

Peroxiredoxin II negatively regulates BMP2-induced osteoblast differentiation and bone formation via PP2A Cα-mediated Smad1/5/9 dephosphorylation

Peroxiredoxin II (Prx II), an antioxidant enzyme in the Prx family, reduces oxidative stress by decreasing the intracellular ROS levels. Osteoblast differentiation is promoted by bone morphogenetic protein 2 (BMP2), which upregulates the expression of osteoblast differentiation marker genes, through Smad1/5/9 phosphorylation. We found that Prx II expression was increased by a high dose of lipopolysaccharide (LPS) but was not increased by a low dose of LPS. Prx II itself caused a decrease in the osteogenic gene expression, alkaline phosphatase (ALP) activity, and Smad1/5/9 phosphorylation induced by BMP2. In addition, BMP2-induced osteogenic gene expression and ALP activity were higher in Prx II knockout (KO) cells than they were in wild-type (WT) cells. These inhibitory effects were mediated by protein phosphatase 2A Cα (PP2A Cα), which was increased and is known to induce the dephosphorylation of Smad1/5/9. The overexpression of Prx II increased the expression of PP2A Cα, and PP2A Cα was not expressed in Prx II KO cells. Moreover, PP2A Cα reduced the level of BMP2-induced osteogenic gene expression and Smad1/5/9 phosphorylation. LPS inhibited BMP2-induced Smad1/5/9 phosphorylation and the suppressed phosphorylation was restored by the PP2A inhibitor okadaic acid (OA). Bone phenotype analyses using microcomputed tomography (μCT) revealed that the Prx II KO mice had higher levels of bone mass than the levels of the WT mice. We hypothesize that Prx II has a negative role in osteoblast differentiation through the PP2A-dependent dephosphorylation of Smad1/5/9.

An antioxidant enzyme actively works to reduce bone synthesis under oxidative stress conditions in order to protect bone cells from damage and cell death. Bone is generated by cells called osteoblasts, which differentiate from stem cells. In osteoporosis and diabetes, excessive reactive oxygen species (ROS) within cells can disrupt osteoblast differentiation. South Korean researchers led by Eun-jung Kim at Kyungpook National University, Daegu, and Won-Gu Jang at Daegu University, Gyeongbuk, have shown that an antioxidant enzyme, peroxiredoxin II (PrxII), helps regulate bone formation under oxidative stress. The team generated PrxII-deficient mice and compared them with healthy normal mice. Under oxidative stress conditions, the mice had higher bone mass and higher expression of genes related to bone formation than the normal mice. PrxII limits osteoblast differentiation during elevated ROS by influencing associated protein activity and signalling pathways.

Peroxiredoxin 4 ameliorates amyloid beta oligomer-mediated apoptosis by inhibiting ER-stress in HT-22 hippocampal neuron cells

Alzheimer's disease (AD) is a neurodegenerative disorder caused by amyloid beta oligomers (AβO), which induce cell death by triggering oxidative stress and endoplasmic reticulum (ER) stress. Oxidative stress is regulated by antioxidant enzymes, including peroxiredoxins. Peroxiredoxins (Prx) are classified into six subtypes, based on their localization and cysteine residues, and protect cells by scavenging hydrogen peroxide (H₂O₂). Peroxiredoxin 4 (Prx4) is unique in being localized to the ER; however, whether Prx4 protects neuronal cells from AβO-induced toxicity remains unclear, although Prx4 expression is upregulated in AβO-induced oxidative stress and ER stress. In this study, we established HT-22 cells in which Prx4 was either overexpressed or silenced to investigate its role in AβO-induced toxicity. AβO-stimulation of HT-22 cells with overexpressed Prx4 caused decreases in both AβO-induced ROS and ER stress (followed by ER expansion). In contrast, AβO stimulation caused increases in both ROS and ER stress that were notably higher in HT-22 cells with silenced Prx4 expression than in HT-22 cells. Consequently, Prx4 overexpression decreased apoptotic cell death and ameliorated the AβO-induced increase in intracellular Ca²⁺. Therefore, we conclude that Prx4 has a protective effect against AβO-mediated oxidative stress, ER stress, and neuronal cell death. Furthermore, these results suggest that Prx4 may be a target for preventing AβO toxicity in AD. Graphical abstract .

Modulation of Hippocampal Antioxidant Defense System in Chronically Stressed Rats by Lithium

This study examined the effects of lithium on gene expression and activity of the antioxidant enzymes copper zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) in the hippocampus of chronically stressed rats. In addition, we examined the effects of lithium on anxiety behaviors, hippocampal concentrations of dopamine (DA) and malondialdehyde (MDA), protein levels of brain-derived neurotrophic factor (BDNF), tyrosine hydroxylase (TH), dopamine transporter (DAT), and catechol-O-methyltransferase (COMT), as well as activity of monoamine oxidase (MAO) in chronically stressed rats. The investigated parameters were quantified by real-time RT-PCR, Western blot analyses, and assays of enzyme activities. We found that lithium did not change gene expression of SOD1, CAT, GPx, and GR but decreased gene expression of SOD2 in chronically stressed rats. A very important result in this study was that lithium treatment decreased the enzyme activities of SOD1 and SOD2 but increased the enzyme activities of GPx and GR in stress condition, which indicates the control of redox balance. The reduced concentration of MDA confirms this. In addition, we found that lithium treatment decreased high protein levels of BDNF and DAT in chronically stressed rats to the level found in unstressed animals. Also, lithium treatment increased the expression of TH but decreased the enzyme activity of MAO B, which contributed to the increase of hippocampal concentration of DA in chronically stressed rats to the level of unstressed animals. Finally, lithium treatment in animals exposed to chronic stress increased the time spent in open arms. Lithium-induced modulation of hippocampal antioxidant status and attenuation of oxidative stress stabilized behavior in animals with high anxiety index. In addition, reduced oxidative stress was followed by the changes of both turnover of DA and levels of BDNF protein in chronically stressed rats treated with lithium. These findings may be important in preclinical research of the effects of lithium on oxidative stress level in pathological conditions.

Attenuating Spinal Cord Injury by Conditioned Medium from Bone Marrow Mesenchymal Stem Cells

Spinal cord injury (SCI) is a devastating neurological condition and might even result in death. However, current treatments are not sufficient to repair such damage. Bone marrow mesenchymal stem cells (BM-MSC) are ideal transplantable cells which have been shown to modulate the injury cascade of SCI mostly through paracrine effects. The present study investigates whether systemic administration of conditioned medium from MSCs (MSCcm) has the potential to be efficacious as an alternative to cell-based therapy for SCI. In neuron-glial cultures, MSC coculture effectively promoted neuronal connection and reduced oxygen glucose deprivation-induced cell damage. The protection was elicited even if neuron-glial culture was used to expose MSCcm, suggesting the effects possibly from released fractions of MSC. In vivo, intravenous administration of MSCcm to SCI rats significantly improved behavioral recovery from spinal cord injury, and there were increased densities of axons in the lesion site of MSCcm-treated rats compared to SCI rats. At early days postinjury, MSCcm treatment upregulated the protein levels of Olig 2 and HSP70 and also increased autophage-related proteins in the injured spinal cords. Together, these findings suggest that MSCcm treatment promotes spinal cord repair and functional recovery, possibly via activation of autophagy and enhancement of survival-related proteins.

Cancer-Associated Function of 2-Cys Peroxiredoxin Subtypes as a Survival Gatekeeper

Cancer cells are abnormal cells that do not comply with tissue homeostasis but undergo uncontrolled proliferation. Such abnormality is driven mostly by somatic mutations on oncogenes and tumor suppressors. Cancerous mutations show intra-tumoral heterogeneity across cancer types and eventually converge into the self-activation of proliferative signaling. While transient production of intracellular reactive oxygen species (ROS) is essential for cell signaling, its persistent production is cytotoxic. Thus, cancer cells require increased levels of intracellular ROS for continuous proliferation, but overexpress cellular peroxidase enzymes, such as 2-Cys peroxiredoxins, to maintain ROS homeostasis. However, suppression of 2-Cys peroxiredoxins has also been reported in some metastatic cancers. Hence, the cancer-associated functions of 2-Cys peroxiredoxins must be illuminated in the cellular context. In this review, we describe the distinctive signaling roles of 2-Cys peroxiredoxins beyond their intrinsic ROS-scavenging role in relation to cancer cell death and survival.

NADPH-dependent and -independent disulfide reductase systems

Over the past seven decades, research on autotrophic and heterotrophic model organisms has defined how the flow of electrons ("reducing power") from high-energy inorganic sources, through biological systems, to low-energy inorganic products like water, powers all of Life's processes. Universally, an initial major biological recipient of these electrons is nicotinamide adenine dinucleotide-phosphate, which thereby transits from an oxidized state (NADP+) to a reduced state (NADPH). A portion of this reducing power is then distributed via the cellular NADPH-dependent disulfide reductase systems as sequential reductions of disulfide bonds. Along the disulfide reduction pathways, some enzymes have active sites that use the selenium-containing amino acid, selenocysteine, in place of the common but less reactive sulfur-containing cysteine. In particular, the mammalian/metazoan thioredoxin systems are usually selenium-dependent as, across metazoan phyla, most thioredoxin reductases are selenoproteins. Among the roles of the NADPH-dependent disulfide reductase systems, the most universal is that they provide the reducing power for the production of DNA precursors by ribonucleotide reductase (RNR). Some studies, however, have uncovered examples of NADPH-independent disulfide reductase systems that can also support RNR. These systems are summarized here and their implications are discussed.

Peroxiredoxin II Regulates Cancer Stem Cells and Stemness-Associated Properties of Cancers

Cancer stem cells (CSCs) represent a sub-population of cancer cells with the ability to regulate stemness-associated properties which are specifically responsible for unlimited growth of cancers, generation of diverse cancer cells in differentiated state and resistance to existing chemotherapy and radiotherapy. Even though, current therapies destroy majority of cancer cells, it is believed to leave CSCs without eradicating which may be the conceptualization for chemoresistance and radio-resistance. Reactive oxygen species (ROS) maintain stem cells and regulate the stemness-associated properties of cancers. Beyond the maximum limit, ROS can damage cellular functions of cancers by subjecting them to oxidative stress. Thus, maintenance of ROS level plays an important role in cancers to regulate stemness-associated properties. Peroxiredoxin II (Prx II) is a member of peroxiredoxin antioxidant enzyme family which considers as a regulator of ROS in cellular environments by modulating redox status to maintain CSC phenotype and stemness properties. Prx II has cell type-dependent expression in various types of cancer cells and overexpression or silenced expression of Prx II in cancers is associated with stem cell phenotype and stemness-associated properties via activation or deactivation of various signaling pathways. In this review, we summarized available studies on Prx II expression in cancers and the mechanisms by which Prx II takes parts to regulate CSCs and stemness-associated properties. We further discussed the potential therapeutic effects of altering Prx II expression in cancers for better anticancer strategies by sensitizing cancer cells and stem cells to oxidative stress and inhibiting stemness-associated properties.

Molecular characterization of a typical 2-Cys thioredoxin peroxidase from the Asiatic rice borer Chilo suppressalis and its role in oxidative stress

In insects, thioredoxin peroxidase (TPX) plays an important role in protecting against oxidative damage. However, studies on the molecular characteristics of TPXs in the Asiatic rice borer, Chilo suppressalis, are limited. In this work, a cDNA sequence (CsTpx3) encoding a TPX was identified from C. suppressalis. The deduced CsTPX3 protein shares high sequence identity and two positionally conserved cysteines with orthologs from other insect species, and was classified as a typical 2-Cys TPX. CsTpx3 was expressed most highly during the fifth-instar larval stage, and transcripts were most abundant in the midgut. Recombinant CsTPX3 protein expressed in Escherichia coli displayed the expected peroxidase activity by removing H₂ O₂ . Furthermore, CsTPX3 protected DNA from oxidative damage, and E. coli cells overexpressing CsTPX3 exhibited long-term resistance to oxidative stress. Exposure to various oxidative stressors, such as cold (8°C), heat (35°C), bacteria (E. coli), and two insecticides (chlorpyrifos and lambda-cyhalothrin), significantly upregulated transcription of CsTpx3. However, exposure to abamectin had no such effect. Our results provide valuable information for future studies on the antioxidant mechanism in this insect species.

Peroxidase expression is decreased by palmitate in cultured podocytes but increased in podocytes of advanced diabetic nephropathy

High levels of serum free fatty acids (FFAs) are associated with lipotoxicity and type 2 diabetes. Palmitic acid (PA) is the predominant circulating saturated FFA. PA induces mitochondrial superoxide and hydrogen peroxide (H₂O ₂) generation in cultured podocytes. To elucidate the role of PA in antioxidant defense systems in diabetic nephropathy (DN), cultured podocytes were exposed to 250 μM PA for 1–24 hr, and protein expressions of catalase, peroxiredoxins (Prxs), and glutathione peroxidase (GPx) were examined by western blot analysis. PA induced an early transient increase in the Prx1, Prx2, and GPx1 levels in podocytes, but not catalase. Long‐term exposure of PA to podocytes significantly decreased the protein levels of Prx1, Prx2, GPx1, and catalase. Coincubation of PA‐treated cells with oleic acid, however, restored the expression of these proteins. In advanced human diabetic glomeruli, H₂O₂ generation was elevated as shown by increased fluorescence of dichlorofluorescein. Strong immunostaining for Prx1, Prx2, GPx1, and catalase was observed in the podocytes of advanced human DN, wherein transforming growth factor‐β1 staining was also positive. These results suggest that podocytes are susceptible to PA‐induced oxidative damage with impaired peroxidase activity and that peroxidases have futile antioxidant effects in the podocytes in the late stages of DN. Given this, PA‐induced podocyte injury via inadequate peroxidase response to H₂O₂ appears to play an important role in the pathogenesis of DN.

Peroxiredoxin 5 regulates adipogenesis-attenuating oxidative stress in obese mouse models induced by a high-fat diet

Elevated levels of reactive oxygen species (ROS) are a hallmark of obesity. Peroxiredoxin 5 (Prx5), which is a cysteine-dependent peroxidase enzyme, has an intensive ROS scavenging activity because it is located in the cytosol and mitochondria. Therefore, we focused on the role of Prx5 in regulating mitochondrial ROS and adipogenesis. We demonstrated that Prx5 expression was upregulated during adipogenesis and Prx5 overexpression suppressed adipogenesis by regulating cytosolic and mitochondrial ROS generation. Silencing Prx5 promoted preadipocytes to differentiate into adipocytes accumulating lipids by activating adipogenic protein expression. Prx5-deletion mice fed on a high-fat diet (HFD) exhibited significant increase in body weight, enormous fat pads, and adipocyte hypertrophy in comparison to wild type mice. Prx5 deletion also remarkably induced adipogenesis-related gene expression in white adipose tissue. These phenotypic changes in Prx5-deletion mice were accompanied with lipid metabolic disorders, such as excessive lipid accumulation in the liver, severe hepatic steatosis, and high levels of triglyceride in the serum. These results demonstrated that Prx5 deletion increased the susceptibility to HFD-induced obesity and several of its associated metabolic disorders. In conclusion, we suggest that Prx5 inhibits adipogenesis by modulating ROS generation and adipogenic gene expression, implying that Prx5 may serve as a potential strategy to prevent and treat obesity.