The Role of Hydrogen Peroxide and Peroxiredoxins throughout the Cell Cycle

Kaempferol as an Alternative Cryosupplement for Bovine Spermatozoa: Cytoprotective and Membrane-Stabilizing Effects

Kaempferol (KAE) is a natural flavonoid with powerful reactive oxygen species (ROS) scavenging properties and beneficial effects on ex vivo sperm functionality. In this paper, we studied the ability of KAE to prevent or ameliorate structural, functional or oxidative damage to frozen-thawed bovine spermatozoa. The analysis focused on conventional sperm quality characteristics prior to or following thermoresistance tests, namely the oxidative profile of semen alongside sperm capacitation patterns, and the levels of key proteins involved in capacitation signaling. Semen samples obtained from 30 stud bulls were frozen in the presence of 12.5, 25 or 50 μM KAE and compared to native ejaculates (negative control-CtrlN) as well as semen samples cryopreserved in the absence of KAE (positive control-CtrlC). A significant post-thermoresistance test maintenance of the sperm motility (p < 0.001), membrane (p < 0.001) and acrosome integrity (p < 0.001), mitochondrial activity (p < 0.001) and DNA integrity (p < 0.001) was observed following supplementation with all KAE doses in comparison to CtrlC. Experimental groups supplemented with all KAE doses presented a significantly lower proportion of prematurely capacitated spermatozoa (p < 0.001) when compared with CtrlC. A significant decrease in the levels of the superoxide radical was recorded following administration of 12.5 (p < 0.05) and 25 μM KAE (p < 0.01). At the same time, supplementation with 25 μM KAE in the cryopreservation medium led to a significant stabilization of the activity of Mg2+-ATPase (p < 0.05) and Na+/K+-ATPase (p < 0.0001) in comparison to CtrlC. Western blot analysis revealed that supplementation with 25 μM KAE in the cryopreservation medium prevented the loss of the protein kinase A (PKA) and protein kinase C (PKC), which are intricately involved in the process of sperm activation. In conclusion, we may speculate that KAE is particularly efficient in the protection of sperm metabolism during the cryopreservation process through its ability to promote energy synthesis while quenching excessive ROS and to protect enzymes involved in the process of sperm capacitation and hyperactivation. These properties may provide supplementary protection to spermatozoa undergoing the freeze-thaw process.

Effect of Ginger Root Extract on Intestinal Oxidative Status and Mucosal Morphometrics in Broiler Chickens

This study was designed to assess the effect of ginger root extract (GRE) supplementation on the oxidative status and intestinal mucosal development in broiler chickens for 6 weeks. Day-old chicks (Ross 708 strain, n = 432) were distributed into six treatments with six replicate of twelve birds each: Negative CON (basal), MX (basal diet + bacitracin methylene disalicylate (BMD) 0.055 g/kg diet), GRE-1 (basal diet + 0.375% GRE), GRE-2 (basal diet + 0.75% GRE), GRE-3 (basal diet + 1.5% GRE), GRE-4 (basal diet + 3% GRE). Growth indices, goblets cell count, mucin (MUC2) in ileum tissue, antioxidant (SOD, CAT, and GPX) in ileum and liver, biological antioxidant potential (BAP), and reactive oxygen metabolite level in blood and intestinal villi measurement were determined. Body weight (BW) was highest (p < 0.05) in all groups except GRE-4, body weight gain (BWG) was best in GRE-1, while FCR was least in all groups except GRE-4. Optimum MUC2 gene expression, SOD, CAT, blood antioxidants, and intestinal morphometric values were observed in GRE-3. The inclusion of ginger root extract up to 1.5% improved growth and reduced oxidative stress while enhancing mucosal development in broiler chicks.

Reactive Oxygen Species (ROS)-Assisted Nano-Therapeutics Surface-Decorated with Epidermal Growth Factor Fragments for Enhanced Wound Healing

In this study, stimuli-responsive liberation of an epidermal growth factor fragment (EGFfr) is accomplished using nanofibrous meshes to improve wound healing effects. Electrospun nanofibers are fragmented by mechanical milling, followed by aminolysis to fabricate powdered nanofibrils (NFs). EGFfrs are covalently immobilized on NFs via thioketal linkers (EGFfr@TK@NF) for reactive oxygen species (ROS)-dependent liberation. EGFfr@TK@NF exhibits ROS-responsive liberation of EGFfr from the matrix at hydrogen peroxide (H2 O2 ) concentrations of 0-250 mm. Released EGFfr is confirmed to enhance the migration of HaCaT cell monolayers, and keratinocytic gene expression levels are significantly enhanced when H2 O2 is added to obtain the released fraction of NFs. An in vivo study on the dorsal wounds of mice reveals that EGFfr-immobilized NFs improve the expression levels of keratin1, 5, and 14 for 2 weeks when H2 O2 is added to the wound sites, suggesting that the wounded skin is re-epithelized with the original epidermis. Thus, EGFfrs-immobilized NFs are anticipated to be potential nanotherapeutics for wound treatment in combination with the conventional disinfection process with H2 O2 .

Agar plate-based activity assay for easy and fast screening of recombinant Pichia pastoris expressing unspecific peroxygenases

Unspecific peroxygenases (UPOs) are promising biocatalysts that catalyze oxyfunctionalization reactions without the need for costly cofactors. Pichia pastoris (reclassified as Komagataella phaffii) is considered an attractive host for heterologous expression of UPOs. However, integration of UPO-expression cassettes into the genome via a single cross-over yields recombinant Pichia transformants with different UPO gene copy numbers resulting in different expression levels. Selection of the most productive Pichia transformants by a commonly used screening in liquid medium in 96-well plates is laborious and lasts up to 5 days. In this work, we developed a simple two-step agar plate-based assay to screen P. pastoris transformants for UPO activity with less effort, within shorter time, and without automated screening devices. After cell growth and protein expression on agar plates supplemented with methanol and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), an additional top agar layer supplemented with ABTS and peroxide is added. UPO activity is visualized within 15 min by formation of green zones around UPO-secreting P. pastoris transformants. The assay was validated with two UPOs, AbrUPO from Aspergillus brasiliensis and evolved PaDa-I from Agrocybe aegerita. The assay results were confirmed in a quantitative 96-deep well plate screening in liquid medium.

Influence of tomato processing by-product extract as dietary supplementation on growth performance, carcass characteristics and antioxidant status of growing rabbits under high ambient temperature

This study evaluated the effects of dietary supplementation of tomato processing by-product extract (TPBE) on growth performance, carcass characteristics and antioxidant status of growing rabbits under high ambient temperature. A total of eighty weaned New Zealand White (NZW) male rabbits (6-weeks-old; initial body weight, 730.28 ± 36.05 g) were randomly assigned to 4 groups. The first group was the control without supplementation; while the other groups were fed diets supplemented with 100, 200 and 250 mg TPBE/kg. The results showed that TPBE contained 211.85 mg/100g as total phenols and total flavones of 303.36 mg/100g. Rabbits fed a 250 mg TPBE-supplemented diet showed the heaviest body weight, the lowest feed intake and the best feed conversion ratio. TPBE diets reduced mortality percentage. Dietary supplementation of 250 mg TPBE had the highest dressing percentage. Plasma total protein, globulin, catalase and glutathione peroxidase of rabbits fed diets supplemented with 200 and 250 mg TPBE were high. Plasma total cholesterol, triglycerides, plasma hydrogen peroxide and malondialdehyde concentrations were decreased with dietary levels of TPBE. Rabbits fed 250 mg TPBE had higher T-AOC than the other groups. TPBE supplemented diets improved net revenue and economic efficiency. Conclusively, TPBE is containing appreciable content of polyphenols and flavonoids and the dietary supplementation of TPBE (250 mg/kg diet) had a positive impact on growth performance, reducing mortality and enhancing the antioxidant status of rabbits reared under high ambient temperature.

Dynamics of redox signaling in aging via autophagy, inflammation, and senescence

Review paper attempts to explain the dynamic aspects of redox signaling in aging through autophagy, inflammation, and senescence. It begins with ROS source in the cell, then states redox signaling in autophagy, and regulation of autophagy in aging. Next, we discuss inflammation and redox signaling with various pathways involved: NOX pathway, ROS production via TNF-α, IL-1β, xanthine oxidase pathway, COX pathway, and myeloperoxidase pathway. Also, we emphasize oxidative damage as an aging marker and the contribution of pathophysiological factors to aging. In senescence-associated secretory phenotypes, we link ROS with senescence, aging disorders. Relevant crosstalk between autophagy, inflammation, and senescence using a balanced ROS level might reduce age-related disorders. Transducing the context-dependent signal communication among these three processes at high spatiotemporal resolution demands other tools like multi-omics aging biomarkers, artificial intelligence, machine learning, and deep learning. The bewildering advancement of technology in the above areas might progress age-related disorders diagnostics with precision and accuracy.

Pitfalls of Mitochondrial Redox Signaling Research

Redox signaling from mitochondria (mt) to the cytosol and plasma membrane (PM) has been scarcely reported, such as in the case of hypoxic cell adaptation or (2-oxo-) 2-keto-isocaproate (KIC) β-like-oxidation stimulating insulin secretion in pancreatic β-cells. Mutual redox state influence between mitochondrial major compartments, the matrix and the intracristal space, and the cytosol is therefore derived theoretically in this article to predict possible conditions, when mt-to-cytosol and mt-to-PM signals may occur, as well as conditions in which the cytosolic redox signaling is not overwhelmed by the mitochondrial antioxidant capacity. Possible peroxiredoxin 3 participation in mt-to-cytosol redox signaling is discussed, as well as another specific case, whereby mitochondrial superoxide release is diminished, whereas the matrix MnSOD is activated. As a result, the enhanced conversion to H2O2 allows H2O2 diffusion into the cytosol, where it could be a predominant component of the H2O2 release. In both of these ways, mt-to-cytosol and mt-to-PM signals may be realized. Finally, the use of redox-sensitive probes is discussed, which disturb redox equilibria, and hence add a surplus redox-buffering to the compartment, where they are localized. Specifically, when attempts to quantify net H2O2 fluxes are to be made, this should be taken into account.

Nano and Technological Frontiers as a Sustainable Platform for Postharvest Preservation of Berry Fruits

Berries are highly perishable and susceptible to spoilage, resulting in significant food and economic losses. The use of chemicals in traditional postharvest protection techniques can harm both human health and the environment. Consequently, there is an increasing interest in creating environmentally friendly solutions for postharvest protection. This article discusses various approaches, including the use of "green" chemical compounds such as ozone and peracetic acid, biocontrol agents, physical treatments, and modern technologies such as the use of nanostructures and molecular tools. The potential of these alternatives is evaluated in terms of their effect on microbial growth, nutritional value, and physicochemical and sensorial properties of the berries. Moreover, the development of nanotechnology, molecular biology, and artificial intelligence offers a wide range of opportunities to develop formulations using nanostructures, improving the functionality of the coatings by enhancing their physicochemical and antimicrobial properties and providing protection to bioactive compounds. Some challenges remain for their implementation into the food industry such as scale-up and regulatory policies. However, the use of sustainable postharvest protection methods can help to reduce the negative impacts of chemical treatments and improve the availability of safe and quality berries.

Antioxidant Effects of Argan Oil and Olive Oil against Iron-Induced Oxidative Stress: In Vivo and In Vitro Approaches

Recently, the study of the protective powers of medicinal plants has become the focus of several studies. Attention has been focused on the identification of new molecules with antioxidant and chelating properties to counter reactive oxygen species (ROS) involved as key elements in several pathologies. Considerable attention is given to argan oil (AO) and olive oil (OO) due to their particular composition and preventive properties. Our study aimed to determine the content of AO and OO on phenolic compounds, chlorophylls, and carotenoid pigments and their antioxidant potential by FRAP and DPPH tests. Thus, several metallic elements can induce oxidative stress, as a consequence of the formation of ROS. Iron is one of these metal ions, which participates in the generation of free radicals, especially OH from H2O2 via the Fenton reaction, initiating oxidative stress. To study the antioxidant potential of AO and OO, we evaluated their preventives effects against oxidative stress induced by ferrous sulfate (FeSO4) in the protozoan Tetrahymena pyriformis and mice. Then, we evaluated the activities of the enzymatic (superoxide dismutase (SOD), glutathione peroxidase (GPx)) and metabolite markers (lipid peroxidation (MDA) and glutathione (GSH)) of the antioxidant balance. The results of the antioxidant compounds show that both oils contain phenolic compounds and pigments. Moreover, AO and OO exhibit antioxidant potential across FRAP and DPPH assays. On the other hand, the results in Tetrahymena pyriformis and mice show a variation in the level of iron-changed SOD and GPx activities and MDA and GSH levels. By contrast, treating Tetrahymena pyriformis and mice with argan and olive oils shows significant prevention in the SOD and GPx activities. These results reveal that the iron-changed ROS imbalance can be counteracted by AO and OO, which is probably related to their composition, especially their high content of polyphenols, sterols, and tocopherols, which is underlined by their antioxidant activities.

Debaryomyces hansenii supplementation in low fish meal diets promotes growth, modulates microbiota and enhances intestinal condition in juvenile marine fish

BACKGROUND

The development of a sustainable business model with social acceptance, makes necessary to develop new strategies to guarantee the growth, health, and well-being of farmed animals. Debaryomyces hansenii is a yeast species that can be used as a probiotic in aquaculture due to its capacity to i) promote cell proliferation and differentiation, ii) have immunostimulatory effects, iii) modulate gut microbiota, and/or iv) enhance the digestive function. To provide inside into the effects of D. hansenii on juveniles of gilthead seabream (Sparus aurata) condition, we integrated the evaluation of the main key performance indicators coupled with the integrative analysis of the intestine condition, through histological and microbiota state, and its transcriptomic profiling.

RESULTS

After 70 days of a nutritional trial in which a diet with low levels of fishmeal (7%) was supplemented with 1.1% of D. hansenii (17.2 × 10⁵ CFU), an increase of ca. 12% in somatic growth was observed together with an improvement in feed conversion in fish fed a yeast-supplemented diet. In terms of intestinal condition, this probiotic modulated gut microbiota without affecting the intestine cell organization, whereas an increase in the staining intensity of mucins rich in carboxylated and weakly sulphated glycoconjugates coupled with changes in the affinity for certain lectins were noted in goblet cells. Changes in microbiota were characterized by the reduction in abundance of several groups of Proteobacteria, especially those characterized as opportunistic groups. The microarrays-based transcriptomic analysis found 232 differential expressed genes in the anterior-mid intestine of S. aurata, that were mostly related to metabolic, antioxidant, immune, and symbiotic processes.

CONCLUSIONS

Dietary administration of D. hansenii enhanced somatic growth and improved feed efficiency parameters, results that were coupled to an improvement of intestinal condition as histochemical and transcriptomic tools indicated. This probiotic yeast stimulated host-microbiota interactions without altering the intestinal cell organization nor generating dysbiosis, which demonstrated its safety as a feed additive. At the transcriptomic level, D. hansenii promoted metabolic pathways, mainly protein-related, sphingolipid, and thymidylate pathways, in addition to enhance antioxidant-related intestinal mechanisms, and to regulate sentinel immune processes, potentiating the defensive capacity meanwhile maintaining the homeostatic status of the intestine.

Oxygen-releasing biomaterials for chronic wounds breathing: From theoretical mechanism to application prospect

Chronic wounds have always been considered as "gordian knots" in medicine, in which hypoxia plays a key role in blocking healing. To address this challenge, although tissue reoxygenation therapy based on hyperbaric oxygen therapy (HBOT) has been performed clinically for several years, the bench to bedside still urges the evolution of oxygen-loading and -releasing strategies with explicit benefits and consistent outcome. The combination of various oxygen carriers with biomaterials has gained momentum as an emerging therapeutic strategy in this field, exhibiting considerable application potential. This review gives an overview of the essential relationship between hypoxia and delayed wound healing. Further, detailed characteristics, preparation methods and applications of various oxygen-releasing biomaterials (ORBMs) will be elaborated, including hemoglobin, perfluorocarbon, peroxide, and oxygen-generating microorganisms, those biomaterials are applied to load, release or generate a vast of oxygen to relieve the hypoxemia and bring the subsequent cascade effect. The pioneering papers regarding to the ORBMs practice are presented and trends toward hybrid and more precise manipulation are summarized.

Probing Oxidant Effects on Superoxide Dismutase 1 Oligomeric States in Live Cells Using Single-Molecule Fluorescence Anisotropy

The protein Cu/Zn superoxide dismutase (SOD1) is known to function as a dimer, but its concentration in cells (∼50 μM) and the dimerization constant (K d of 500 μM) results suggest that it exists in a monomer-dimer equilibrium. It is unclear how the oligomeric state of SOD1 changes when cells are initially exposed to high levels of extracellular oxidative stress. To address this problem, we introduced the single-molecule fluorescence anisotropy (smFA) assay to explore SOD1 oligomeric states in live COS7 cells. smFA specifically probes the fluorescence polarization changes caused by molecular rotations where the fast-rotating molecules (either due to smaller hydrodynamic volume or less viscous environments) deteriorate the emission polarization and thus lower the anisotropy. After validating that smFA is effective in distinguishing monomeric and dimeric fluorescence proteins, we overexpressed SOD1 in live COS7 cells and investigated how its oligomeric state changes under basal, 2 h, and 24 h 100 μM H2O2 treatments. We found that treating cells with H2O2 promotes SOD1 dimerization and decreases cellular viscosity in 2 h. Interestingly, prolonged H2O2 treatments show similar results as the basal conditions, indicating that cells return to a steady state similar to the basal state after 24 h, despite the presence of H2O2. Our results demonstrate that SOD1 changes its oligomeric state equilibrium in response to extracellular oxidative stresses. smFA will open new opportunities to explore the relationship between the SOD1 oligomer state and its H2O2-based signaling and transcription regulation roles.

Epicatechin Prevents Cryocapacitation of Bovine Spermatozoa through Antioxidant Activity and Stabilization of Transmembrane Ion Channels

Epicatechin (EPC) is a flavonoid belonging to the family of catechins; it has been described as a powerful scavenger of a wide spectrum of reactive oxygen species (ROS) and a modulator of ex vivo sperm vitality. In this study, we assessed the potential protective abilities of EPC on cryopreserved bovine spermatozoa. We focused on conventional quality parameters, as well as the oxidative profile of spermatozoa alongside capacitation patterns, and expression profiles of proteins involved in the process of capacitation. Semen samples were cryopreserved in the presence of 25, 50 or 100 μmol/L EPC and compared to native semen (negative control) as well as ejaculates frozen in the absence of EPC (positive control). A dose-dependent improvement of conventional sperm quality parameters was observed following EPC administration, particularly in case of the sperm motility, membrane, acrosome and DNA integrity in comparison to the positive control. Experimental groups exposed to all EPC doses presented with a significantly lower proportion of capacitated spermatozoa as opposed to the positive control. While no significant effects of EPC were observed in cases of superoxide production, a significant decrease in the levels of hydrogen peroxide and hydroxyl radical were recorded particularly in the experimental groups supplemented with 50 and 100 μmol/L EPC. Western blot analysis revealed that supplementation of particularly 100 μmol/L EPC to the semen extender prevented the loss of the cation channel of sperm (CatSper) isoforms 1 and 2, sodium bicarbonate cotransporter (NBC) and protein kinase A (PKA), which play important roles in the process of sperm capacitation. In summary, we may hypothesize that EPC is particularly effective in the stabilization of the sperm membrane during the freeze-thaw process through its ability to quench ROS involved in damage to the membrane lipids and to prevent the loss of membrane channels crucial to initiate the process of sperm capacitation. These attributes of EPC provide an additional layer of protection to spermatozoa exposed to low temperatures, which may be translated into a higher post-thaw structural integrity and functional activity of male gametes.

Adsorption Kinetic Model Predicts and Improves Reliability of Electrochemical Serotonin Detection

Serotonin (5-HT) is a neurotransmitter involved in many biophysiological processes in the brain and in the gastrointestinal tract. Electrochemical methods are commonly used to quantify 5-HT, but their reliability may suffer due to the time-dependent nature of adsorption-limited 5-HT detection, as well as electrode fouling over repeated measurements. Mathematical characterization and modeling of adsorption-based electrochemical signal generation would improve reliability of 5-HT measurement. Here, a model was developed to track 5-HT electrode adsorption and resulting current output by combining Langmuir adsorption kinetic equations and adsorption-limited electrochemical equations. 5-HT adsorption binding parameters were experimentally determined at a carbon-nanotube coated Au electrode: K_D = 7 × 10^-7 M, k_on = 130 M^-1 s^-1, k_off = 9.1 × 10^-5 s^-1. A computational model of 5-HT adsorption was then constructed, which could effectively predict 5-HT fouling over 50 measurements (R² = 0.9947), as well as predict electrode responses over varying concentrations and measurement times. The model aided in optimizing the measurement of 5-HT secreted from a model enterochromaffin cell line-RIN14B-minimizing measurement time. The presented model simplified and improved the characterization of 5-HT detection at the selected electrode. This could be applied to many other adsorption-limited electrochemical analytes and electrode types, contributing to the improvement of application-specific modeling and optimization processes.

Free Radicals and Oxidative Stress: Signaling Mechanisms, Redox Basis for Human Diseases, and Cell Cycle Regulation

Free radicals contain one or more unpaired electrons in their valence shell, thus making them unstable, short-lived, and highly reactive species. Excessive generation of these free radicals ultimately leads to oxidative stress causing oxidation and damage to significant macromolecules in the living system and essentially disrupting signal transduction pathways and antioxidants equilibrium. At lower concentrations, ROS serves as "second messengers," influencing many physiological processes in the cell. However, higher concentrations beyond cell capacity cause oxidative stress, contributing to human pathologies such as diabetes, cancer, Parkinson's disease, cardiovascular diseases, cataract, asthma, hypertension, atherosclerosis, arthritis, and Alzheimer's disease. Signaling pathways such as NF-κB, MAPKs, PI3K/Akt/ mTOR, and Keap1-Nrf2- ARE modulate the detrimental effects of oxidative stress by increasing the expression of cellular antioxidant defenses, phase II detoxification enzymes, and decreased production of ROS. Free radicals such as H2O2 are indeed needed for the advancement of the cell cycle as these molecules influence DNA, proteins, and enzymes in the cell cycle pathway. In the course of cell cycle progression, the cellular redox environment becomes more oxidized, moving from the G1 phase, becoming higher in G2/M and moderate in the S phase. Signals in the form of an increase in cellular pro-oxidant levels are required, and these signals are often terminated by a rise in the amount of antioxidants and MnSOD with a decrease in the level of cyclin D1 proteins. Therefore, understanding the mechanism of cell cycle redox regulation will help in the therapy of many diseases.

In vitro effects of combustion generated carbon dots on cellular parameters in healthy and cancerous breast cells

Carbon nanomaterials are an inventive class of materials with wide applications in state-of-the-art bioimaging and therapeutics. They allow a broad range of tunable and integrated advantages of structural flexibility, chemical and thermal stability, upright electrical conductivity, and the option of scale-up and mass production. In the context of nanomedicine, carbon nanomaterials have been used extensively to mitigate the serious side effects of conventional chemotherapy and also to enable early cancer diagnostics, given their wide range of tunable properties. A class of carbon nanomaterials, called carbon dots (CDs) are small carbon-based nanoparticles and have been a valued discovery due to their photoluminescence, low photobleaching, and high surface area to mass ratio. The process of producing these CDs had so far been a high energy demanding process involving wet chemistry for purification. A one-step tunable production of luminescent CDs from fuel rich combustion reactors was recently presented by our group. In this paper, we explore the effects of these yellow luminescent combustion-generated CDs in MCF7 adenocarcinoma and MCF10a normal breast epithelial cells. We observed that these CDs, also at nontoxic doses, can affect basic cellular functions, such as cell cycle and proliferation; induce substantial changes on the physical parameters of the plasma membrane; and change the overall appearance of a cell in terms of morphology.

PUFA-Derived N-Acylethanolamide Probes Identify Peroxiredoxins and Small GTPases as Molecular Targets in LPS-Stimulated RAW264.7 Macrophages

We studied the mechanistic and biological origins of anti-inflammatory poly-unsaturated fatty acid-derived N-acylethanolamines using synthetic bifunctional chemical probes of docosahexaenoyl ethanolamide (DHEA) and arachidonoyl ethanolamide (AEA) in RAW264.7 macrophages stimulated with 1.0 μg mL^-1 lipopolysaccharide. Using a photoreactive diazirine, probes were covalently attached to their target proteins, which were further studied by introducing a fluorescent probe or biotin-based affinity purification. Fluorescence confocal microscopy showed DHEA and AEA probes localized in cytosol, specifically in structures that point toward the endoplasmic reticulum and in membrane vesicles. Affinity purification followed by proteomic analysis revealed peroxiredoxin-1 (Prdx1) as the most significant binding interactor of both DHEA and AEA probes. In addition, Prdx4, endosomal related proteins, small GTPase signaling proteins, and prostaglandin synthase 2 (Ptgs2, also known as cyclooxygenase 2 or COX-2) were identified. Lastly, confocal fluorescence microscopy revealed the colocalization of Ptgs2 and Rac1 with DHEA and AEA probes. These data identified new molecular targets suggesting that DHEA and AEA may be involved in reactive oxidation species regulation, cell migration, cytoskeletal remodeling, and endosomal trafficking and support endocytosis as an uptake mechanism.

Antioxidant Activity of Ruthenium Cyclopentadienyl Complexes Bearing Succinimidato and Phthalimidato Ligands

In these studies, we investigated the antioxidant activity of three ruthenium cyclopentadienyl complexes bearing different imidato ligands: (η⁵-cyclopentadienyl)Ru(CO)₂-N-methoxysuccinimidato (1), (η⁵-cyclopentadienyl)Ru(CO)₂-N-ethoxysuccinimidato (2), and (η⁵-cyclopentadienyl)Ru(CO)₂-N-phthalimidato (3). We studied the effects of ruthenium complexes 1–3 at a low concentration of 50 µM on the viability and the cell cycle of peripheral blood mononuclear cells (PBMCs) and HL-60 leukemic cells exposed to oxidative stress induced by hydrogen peroxide (H₂O₂). Moreover, we examined the influence of these complexes on DNA oxidative damage, the level of reactive oxygen species (ROS), and superoxide dismutase (SOD) activity. We have observed that ruthenium complexes 1–3 increase the viability of both normal and cancer cells decreased by H₂O₂ and also alter the HL-60 cell cycle arrested by H₂O₂ in the sub-G1 phase. In addition, we have shown that ruthenium complexes reduce the levels of ROS and oxidative DNA damage in both cell types. They also restore SOD activity reduced by H₂O₂. Our results indicate that ruthenium complexes 1–3 bearing succinimidato and phthalimidato ligands have antioxidant activity without cytotoxic effect at low concentrations. For this reason, the ruthenium complexes studied by us should be considered interesting molecules with clinical potential that require further detailed research.

Characterization of the Neospora caninum peroxiredoxin: a novel peroxidase and antioxidant enzyme

Neospora caninum, an apicomplexan parasite, is the etiological agent of neosporosis, a disease that leads to neurological symptoms in dogs and abortion in cattle. Vaccine or drug treatments for neosporosis remain to be determined. Therefore, it is of undeniable relevance to investigate new molecules involved in the parasite's successful survival within the host cell. The aim of this study was to characterize the N. caninum peroxiredoxin (NcPrx), an enzyme involved in the redox system of the parasite. The NcPrx amino acid sequence showed high identity and similarity compared to homologues representatives of Apicomplexa phylum. The recombinant NcPrx (rNcPrx) was cloned and expressed in Escherichia coli (BL21) with the predicted molecular weight (22 kDa), and the identity of monomer and dimer forms of rNcPrx was confirmed by mass spectrometry. Native and recombinant NcPrx were detected by ELISA and western blot, using the polyclonal anti-rNcPrx serum. Multiphoton analysis showed that NcPrx is localized in tachyzoite cytosol. H₂O₂ treatment increased the rNcPrx dimerization in vitro, and associated with the in silico data, we suggest that NcPrx belongs to typical 2-Cys Prx group (AhpC/Prx1 family). rNcPrx also increased the H₂O₂ clearance and protected plasmidial DNA under oxidative conditions. Finally, H₂O₂ increased the NcPrx dimerization in intracellular and extracellular tachyzoites suggesting that it is enrolled in H₂O₂ clearance and sensing in N. caninum.

Essential Protective Role of Catalytically Active Antibodies (Abzymes) with Redox Antioxidant Functions in Animals and Humans

During the life of aerobic organisms, the oxygen resulting from numerous reactions is converted into reactive oxygen species (ROS). Many ROS are dangerous due to their high reactivity; they are strong oxidants, and react with various cell components, leading to their damage. To protect against ROS overproduction, enzymatic and non-enzymatic systems are evolved in aerobic cells. Several known non-enzymatic antioxidants have a relatively low specific antioxidant activity. Superoxide dismutases, catalase, glutathione peroxidase, glutathione S-transferase, thioredoxin, and the peroxiredoxin families are the most important enzyme antioxidants. Artificial antibodies catalyzing redox reactions using different approaches have been created. During the past several decades, it has been shown that the blood and various biological fluids of humans and animals contain natural antibodies that catalyze different redox reactions, such as classical enzymes. This review, for the first time, summarizes data on existing non-enzymatic antioxidants, canonical enzymes, and artificial or natural antibodies (abzymes) with redox functions. Comparing abzymes with superoxide dismutase, catalase, peroxide-dependent peroxidase, and H₂O₂-independent oxidoreductase activities with the same activities as classical enzymes was carried out. The features of abzymes with the redox activities are described, including their exceptional diversity in the optimal pH values, dependency and independence on various metal ions, and the reaction rate constants for healthy donors and patients with different autoimmune diseases. The entire body of evidence indicates that abzymes with redox antioxidant activities existing in the blood for a long time compared to enzymes are an essential part of the protection system of humans and animals from oxidative stress.

Molecular Characterization of a New Tetrodotoxin-Binding Protein, Peroxiredoxin-1, from Takifugu bimaculatus

Pufferfish are considered a culinary delicacy but require careful preparation to avoid ingestion of the highly toxic tetrodotoxin (TTX), which accumulates in certain tissues. In this study, the tissue distribution of peroxiredoxin-1 from Takifugu bimaculatus was investigated. The peroxiredoxin-1 protein was obtained by in vitro recombinant expression and purification. The recombinant protein had a strong ability to scavenge hydroxyl radicals, protect superhelical DNA plasmids from oxidative damage, and protect L929 cells from H₂O₂ toxicity through in vitro antioxidant activity. In addition, we verified its ability to bind to tetrodotoxin using surface plasmon resonance techniques. Further, recombinant proteins were found to facilitate the entry of tetrodotoxin into cells. Through these analyses, we identified, for the first time, peroxiredoxin-1 protein from Takifugu bimaculatus as a potential novel tetrodotoxin-binding protein. Our findings provide a basis for further exploration of the application of peroxiredoxin-1 protein and the molecular mechanisms of tetrodotoxin enrichment in pufferfish.

Identification of the AccCDK1 gene in Apis cerana cerana and its relationship with the oxidative stress response

The cyclin-dependent kinase (CDK) protein family plays an important role in regulating life functions, such as the cell cycle and metabolism. This study reports the first cloning and functional analysis of A. cerana cerana CDK1 (AccCDK1). The distribution profile of AccCDK1 in different developmental periods and different tissues was determined. The experimental results showed that the distribution of AccCDK1 was tissue-specific. AccCDK1 distribution at the transcriptional and translational levels was affected by stress conditions induced by H₂O₂, UV, HgCl₂, CdCl₂, extreme temperatures (4 °C, 44 °C) and pesticides (avermectin, lambda-cyhalothrin, haloxyfop-R-methyl, and glyphosate), which resulted in changes in the expression levels. These results suggest that AccCDK1 may have an important part to play in honey bee resistance to stress. The expression of a recombinant AccCDK1 protein in vitro enhanced the antistress capacities of E. coli and yeast, which suggests that AccCDK1 is related to the stress response. When AccCDK1 was silenced, the expression of some antioxidant genes was downregulated, and the enzymatic potencies of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were reduced, which suggests that AccCDK1 takes part in the body's resistance to oxidative stress upon external stimulation by influencing relevant antioxidants. Notably, the survival rate of A. cerana cerana under high-temperature-induced stress decreased after AccCDK1 silencing, which verifies our results. In conclusion, we found that AccCDK1 played an indispensable function in resisting oxidative stress and maintaining normal cellular functions.

Age-associated decline of MondoA drives cellular senescence through impaired autophagy and mitochondrial homeostasis

Accumulation of senescent cells affects organismal aging and the prevalence of age-associated disease. Emerging evidence suggests that activation of autophagy protects against age-associated diseases and promotes longevity, but the roles and regulatory mechanisms of autophagy in cellular senescence are not well understood. Here, we identify the transcription factor, MondoA, as a regulator of cellular senescence, autophagy, and mitochondrial homeostasis. MondoA protects against cellular senescence by activating autophagy partly through the suppression of an autophagy-negative regulator, Rubicon. In addition, we identify peroxiredoxin 3 (Prdx3) as another downstream regulator of MondoA essential for mitochondrial homeostasis and autophagy. Rubicon and Prdx3 work independently to regulate senescence. Furthermore, we find that MondoA knockout mice have exacerbated senescence during ischemic acute kidney injury (AKI), and a decrease of MondoA in the nucleus is correlated with human aging and ischemic AKI. Our results suggest that decline of MondoA worsens senescence and age-associated disease.

Hydrogen peroxide signalling mediates fertilization and post-fertilization development in the red alga Bostrychia moritziana

Reactive oxygen species (ROS) signalling has a multitude of roles in cellular processes throughout biology. We hypothesized that red algal fertilization may offer an interesting model to study ROS-mediated signalling, as the stages of fertilization are complex and unique. We detected the localization of ROS production microscopically and monitored the expression of three homologues of NADPH oxidase in reproductive cells during fertilization. ROS were instantaneously produced by spermatia (sperm) when they attached to female trichogynes, diffused across the cell membrane in the form of H2O2, and triggered ROS generation in the carpogonium (egg) as well as carpogonial branch cells which are not in direct contact with spermatia. The expression of NADPH oxidase homologues, RESPIRATORY BURST OXIDASE HOMOLOGUES (BmRBOHs), began to be up-regulated in the female plant upon gamete binding, peaking during the fertilization process and descending back to their original level after fertilization. Pre-treatment with diphenylene iodonium or caffeine blocked gene expression as well as H2O2 production. Post-fertilization development was also inhibited when the redox state of the plants was perturbed with H2O2 at any time before or after the fertilization. Our results suggest that H2O2 acts as an auto-propagating signalling molecule, possibly through Ca2+ channel activation, and regulates gene expression in fertilization as well as post-fertilization development in red algae.

NADPH Oxidases (NOX): An Overview from Discovery, Molecular Mechanisms to Physiology and Pathology

The reactive oxygen species (ROS)-producing enzyme NADPH oxidase (NOX) was first identified in the membrane of phagocytic cells. For many years, its only known role was in immune defense, where its ROS production leads to the destruction of pathogens by the immune cells. NOX from phagocytes catalyzes, via one-electron trans-membrane transfer to molecular oxygen, the production of the superoxide anion. Over the years, six human homologs of the catalytic subunit of the phagocyte NADPH oxidase were found: NOX1, NOX3, NOX4, NOX5, DUOX1, and DUOX2. Together with the NOX2/gp91phox component present in the phagocyte NADPH oxidase assembly itself, the homologs are now referred to as the NOX family of NADPH oxidases. NOX are complex multidomain proteins with varying requirements for assembly with combinations of other proteins for activity. The recent structural insights acquired on both prokaryotic and eukaryotic NOX open new perspectives for the understanding of the molecular mechanisms inherent to NOX regulation and ROS production (superoxide or hydrogen peroxide). This new structural information will certainly inform new investigations of human disease. As specialized ROS producers, NOX enzymes participate in numerous crucial physiological processes, including host defense, the post-translational processing of proteins, cellular signaling, regulation of gene expression, and cell differentiation. These diversities of physiological context will be discussed in this review. We also discuss NOX misregulation, which can contribute to a wide range of severe pathologies, such as atherosclerosis, hypertension, diabetic nephropathy, lung fibrosis, cancer, or neurodegenerative diseases, giving this family of membrane proteins a strong therapeutic interest.

Immune, inflammatory, autophagic and DNA damage responses to long-term H2O2 exposure in different tissues of common carp (Cyprinus carpio)

Hydrogen peroxide (H₂O₂) is a stable reactive oxygen species (ROS) in aquatic environment, and high concentration of ambient H₂O₂ may directly or indirectly affect aquatic animal health. However, the response mechanism of fish to ambient H₂O₂ has not been well studied yet. Therefore, the aim of the study was to investigate the immune, inflammatory, autophagic and DNA damage responses to long-term H₂O₂ exposure in different tissues of common carp. The results showed that H₂O₂ exposure induced a significant immune response, with alterations in the levels of immune parameters including AKP, ACP, LZM, C3, HSP90 and HSP70 in different tissues. The inflammatory response evoked by H₂O₂ exposure was associated with the activations of TLRs and NF-κB (P65) in the majority of tested tissues. The autophagy process was significantly affected by H₂O₂ exposure, evidenced by the upregulations of the autophagy-related genes in liver, gills, muscle, intestines, heart and spleen and the downregulations in kidney. Meanwhile, the mRNA level of atm, a primary transducer of DNA damage response, was upregulated in liver, gills, intestines and spleen, and the DNA damage was evidenced by increased 8-OHdG level in intestines after H₂O₂ exposure. Moreover, cell cycle regulation-related genes, including cyclin A1, B and/or E1, highly expressed in all tested tissues except heart after H₂O₂ exposure. Interestingly, IBR analysis exhibited that immune, inflammatory, autophagic and DNA damage responses to H₂O₂ exposure were in a dose-dependent and tissue-specific manner. These data may contribute to understanding H₂O₂ toxicity for fish and assessing potential risk of H₂O₂ in aquatic environment.

Crosstalk between endoplasmic reticulum stress and oxidative stress: Focus on protein disulfide isomerase and endoplasmic reticulum oxidase 1

Cellular stress and inflammation, establishing as disease pathology, have reached great heights in the last few decades. Stress conditions such as hyperglycemia, hyperlipidemia and lipoproteins are known to disturb proteostasis resulting in the accumulation of unfolded or misfolded proteins, alteration in calcium homeostasis culminating in unfolded protein response. Protein disulfide isomerase and endoplasmic reticulum oxidase-1 are the key players in protein folding. The protein folding process assisted by endoplasmic reticulum oxidase-1 results in the production of reactive oxygen species in the lumen of the endoplasmic reticulum. Production of reactive oxygen species beyond the quenching capacity of the antioxidant systems perturbs ER homeostasis. Endoplasmic reticulum stress also induces the production of cytokines leading to inflammatory responses. This has been proven to be the major causative factor for various pathophysiological states compared to other cellular triggers in diseases, which further manifests to increased oxidative stress, mitochondrial dysfunction, and altered inflammatory responses, deleterious to cellular physiology and homeostasis. Numerous studies have drawn correlations between the progression of several diseases in association with endoplasmic reticulum stress, redox protein folding, oxidative stress and inflammatory responses. This review aims to provide an insight into the role of protein disulfide isomerase and endoplasmic reticulum oxidase-1 in endoplasmic reticulum stress, unfolded protein response, mitochondrial dysfunction, and inflammatory responses, which exacerbate the progression of various diseases.

Knockout of PRDX6 induces mitochondrial dysfunction and cell cycle arrest at G2/M in HepG2 hepatocarcinoma cells

Peroxiredoxin 6 (PRDX6) has been associated with tumor progression and cancer metastasis. Its acting on phospholipid hydroperoxides and its phospholipase-A2 activity are unique among the peroxiredoxin family and add complexity to its action mechanisms. As a first step towards the study of PRDX6 involvement in cancer, we have constructed a human hepatocarcinoma HepG2^PRDX6-/- cell line using the CRISPR/Cas9 technique and have characterized the cellular response to lack of PRDX6.

Applying quantitative global and redox proteomics, flow cytometry, in vivo extracellular flow analysis, Western blot and electron microscopy, we have detected diminished respiratory capacity, downregulation of mitochondrial proteins and altered mitochondrial morphology. Autophagic vesicles were abundant while the unfolded protein response (UPR), HIF1A and NRF2 transcription factors were not activated, despite increased levels of p62/SQSTM1 and reactive oxygen species (ROS). Insulin receptor (INSR), 3-phosphoinositide-dependent protein kinase 1 (PDPK1), uptake of glucose and hexokinase-2 (HK2) decreased markedly while nucleotide biosynthesis, lipogenesis and synthesis of long chain polyunsaturated fatty acids (LC-PUFA) increased. 254 Cys-peptides belonging to 202 proteins underwent significant redox changes. PRDX6 knockout had an antiproliferative effect due to cell cycle arrest at G2/M transition, without signs of apoptosis.

Loss of PLA2 may affect the levels of specific lipids altering lipid signaling pathways, while loss of peroxidase activity could induce redox changes at critical sensitive cysteine residues in key proteins. Oxidation of specific cysteines in Proliferating Cell Nuclear Antigen (PCNA) could interfere with entry into mitosis. The GSH/Glutaredoxin system was downregulated likely contributing to these redox changes. Altogether the data demonstrate that loss of PRDX6 slows down cell division and alters metabolism and mitochondrial function, so that cell survival depends on glycolysis to lactate for ATP production and on AMPK-independent autophagy to obtain building blocks for biosynthesis. PRDX6 is an important link in the chain of elements connecting redox homeostasis and proliferation.

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A CRISPR-Cas9 based PRDX6 KO human cell line is characterized for the first time.

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Loss of PRDX6 causes mitochondrial dysfunction, autophagy and slow growth rate.

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Glucose uptake and HK2 decrease; nucleotide biosynthesis and lipogenesis increase.

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Oxidation of PCNA Cys residues could be responsible for cell cycle arrest at G2/M.