Specific aquaporins facilitate the diffusion of hydrogen peroxide across membranes

Cadmium exposure induced light/dark- and time-dependent redox changes at subcellular level in Arabidopsis plants

Cadmium (Cd) is one of the most toxic heavy metals for plants and humans. Reactive oxygen species (ROS) are some of the primary signaling molecules produced after Cd treatment in plants but the contribution of different organelles and specific cell types, together with the impact of light is unknown. We used Arabidopsis lines expressing GRX1-roGFP2 (glutaredoxin1-roGFP) targeted to different cell compartments and analysed changes in redox state over 24 h light/dark cycle in Cd-treated leaf discs. We imaged redox state changes in peroxisomes and chloroplasts in leaf tissue. Chloroplasts and peroxisomes were the most affected organelles in the dark and blocking the photosynthetic electron transport chain (pETC) by DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) promotes higher Cd-dependent oxidation in all organelles. Peroxisomes underwent the most rapid changes in redox state in response to Cd and DCMU and silencing chloroplastic NTRC (NADPH thioredoxin reductase C) considerably increases peroxisome oxidation. Total NAD(P)H and cytosolic NADH decreased during exposure to Cd, while Ca+2 content in chloroplasts and cytosol increased in the dark period. Our results demonstrate a Cd-, time- and light-dependent increase of oxidation of all organelles analysed, that could be in part triggered by disturbances in pETC and photorespiration, the decrease of NAD(P)H availability, and differential antioxidants expression at subcellular level.

Inhibition of aquaporin-9 ameliorates severe acute pancreatitis and associated lung injury by NLRP3 and Nrf2/HO-1 pathways

Inflammation, apoptosis and oxidative stress play crucial roles in the deterioration of severe acute pancreatitis-associated acute respiratory distress syndrome (SAP-ARDS). Unfortunately, despite a high mortality rate of 45 %[1], there are limited treatment options available for ARDS outside of last resort options such as mechanical ventilation and extracorporeal support strategies[2]. This study investigated the potential therapeutic role and mechanisms of AQP9 inhibitor RG100204 in two animal models of severe acute pancreatitis, inducing acute respiratory distress syndrome: 1) a sodium-taurocholate induced rat model, and 2) and Cerulein and lipopolysaccharide induced mouse model. RG100204 treatment led to a profound reduction in inflammatory cytokine expression in pancreatic, and lung tissue, in both models. In addition, infiltration of CD68 + and CD11b + cells into these tissues were reduced in RG100204 treated SAP animals, and edema and SAP associated tissue damage were improved. Moreover, we demonstrate that RG100204 reduced apoptosis in the lungs of rat SAP animals, and reduces NF-κB signaling, NLRP3, expression, while profoundly increasing the Nrf2-dependent anti oxidative stress response. We conclude that AQP9 inhibition is a promising strategy for the treatment of pancreatitis and its systemic complications, such as ARDS.

Unlocking peak performance: The role of Nrf2 in enhancing exercise outcomes and training adaptation in humans

Since the discovery of the nuclear factor erythroid-derived 2-like 2 (Nrf2) transcription factor thirty years ago, it has been shown that it regulates more than 250 genes involved in a multitude of biological processes, including redox balance, mitochondrial biogenesis, metabolism, detoxification, cytoprotection, inflammation, immunity, autophagy, cell differentiation, and xenobiotic metabolism. In skeletal muscle, Nrf2 signalling is primarily activated in response to perturbation of redox balance by reactive oxygen species or electrophiles. Initial investigations into human skeletal muscle Nrf2 responses to exercise, dating back roughly a decade, have consistently indicated that exercise-induced ROS production stimulates Nrf2 signalling. Notably, recent studies employing Nrf2 knockout mice have revealed impaired skeletal muscle contractile function characterised by reduced force output and increased fatigue susceptibility compared to wild-type counterparts. These deficiencies partially stem from diminished basal mitochondrial respiratory capacity and an impaired capacity to upregulate specific mitochondrial proteins in response to training, findings corroborated by inducible muscle-specific Nrf2 knockout models. In humans, baseline Nrf2 expression in skeletal muscle correlates with maximal oxygen uptake and high-intensity exercise performance. This manuscript delves into the mechanisms underpinning Nrf2 signalling in response to acute exercise in human skeletal muscle, highlighting the involvement of ROS, antioxidants and Keap1/Nrf2 signalling in exercise performance. Furthermore, it explores Nrf2's role in mediating adaptations to chronic exercise and its impact on overall exercise performance. Additionally, the influence of diet and certain supplements on basal Nrf2 expression and its role in modulating acute and chronic exercise responses are briefly addressed.

Exploring the puzzle of reactive oxygen species acting on root hair cells

Reactive oxygen species (ROS) are essential signaling molecules that enable cells to respond rapidly to a range of stimuli. The ability of plants to recognize various stressors, incorporate a variety of environmental inputs, and initiate stress-response networks depends on ROS. Plants develop resilience and defensive systems as a result of these processes. Root hairs are central components of root biology since they increase the surface area of the root, anchor it in the soil, increase its ability to absorb water and nutrients, and foster interactions between microorganisms. In this review, we specifically focused on root hair cells and we highlighted the identification of ROS receptors, important new regulatory hubs that connect ROS production, transport, and signaling in the context of two hormonal pathways (auxin and ethylene) and under low temperature environmental input related to nutrients. As ROS play a crucial role in regulating cell elongation rates, root hairs are rapidly gaining traction as a very valuable single plant cell model for investigating ROS homeostasis and signaling. These promising findings might soon facilitate the development of plants and roots that are more resilient to environmental stressors.

Functionality of Reactive Oxygen Species (ROS) in Plants: Toxicity and Control in Poaceae Crops Exposed to Abiotic Stress

Agriculture and changing environmental conditions are closely related, as weather changes could adversely affect living organisms or regions of crop cultivation. Changing environmental conditions trigger different abiotic stresses, which ultimately cause the accumulation of reactive oxygen species (ROS) in plants. Common ROS production sites are the chloroplast, endoplasmic reticulum, plasma membrane, mitochondria, peroxisomes, etc. The imbalance in ROS production and ROS detoxification in plant cells leads to oxidative damage to biomolecules such as lipids, nucleic acids, and proteins. At low concentrations, ROS initiates signaling events related to development and adaptations to abiotic stress in plants by inducing signal transduction pathways. In plants, a stress signal is perceived by various receptors that induce a signal transduction pathway that activates numerous signaling networks, which disrupt gene expression, impair the diversity of kinase/phosphatase signaling cascades that manage the stress response in the plant, and result in changes in physiological responses under various stresses. ROS production also regulates ABA-dependent and ABA-independent pathways to mitigate drought stress. This review focuses on the common subcellular location of manufacturing, complex signaling mechanisms, and networks of ROS, with an emphasis on cellular effects and enzymatic and non-enzymatic antioxidant scavenging mechanisms of ROS in Poaceae crops against drought stress and how the manipulation of ROS regulates stress tolerance in plants. Understanding ROS systems in plants could help to create innovative strategies to evolve paths of cell protection against the negative effects of excessive ROS in attempts to improve crop productivity in adverse environments.

Rational design of ROS generation nanosystems to regulate innate immunity of macrophages, dendrtical and natural killing cells for immunotherapy

Innate immunity serves as the first line of host defense in the body against pathogenic infections or malignant diseases. Reactive oxygen species (ROS), as vital signaling mediators, can efficiently elicit innate immune responses to oxidative-related stress or damage. In the era of nanomedicine, various immunostimulatory nanosystems have been extensively designed and synthesized to elicit immune responses for the immunotherapy of cancer or infectious diseases. In this review, we emphasize that ROS derived from nanosystems regulates innate immune cells to potentiate immunotherapeutic efficacy, such as primarily dendritic cells, macrophages, or natural killer cells. Meanwhile, we also summarize the pathway of ROS generation triggered by exogenous nanosystems in innate immune cells of DCs, macrophages, and NK cells.

Insights into crucial molecules and protein channels involved in pig sperm cryopreservation

Cryopreservation is the most efficient procedure for long-term preservation of mammalian sperm; however, its use is not currently dominant for boar sperm before its use for artificial insemination. In fact, freezing and thawing have an extensive detrimental effect on sperm function and lead to impaired fertility. The present work summarises the basis of the structural and functional impact of cryopreservation on pig sperm that have been extensively studied in recent decades, as well as the molecular alterations in sperm that are related to this damage. The wide variety of mechanisms underlying the consequences of alterations in expression levels and structural modifications of sperm proteins with diverse functions is detailed. Moreover, the use of cryotolerance biomarkers as predictors of the potential resilience of a sperm sample to the cryopreservation process is also discussed. Regarding the proteins that have been identified to be relevant during the cryopreservation process, they are classified according to the functions they carry out in sperm, including antioxidant function, plasma membrane protection, sperm motility regulation, chromatin structure, metabolism and mitochondrial function, heat-shock response, premature capacitation and sperm-oocyte binding and fusion. Special reference is made to the relevance of sperm membrane channels, as their function is crucial for boar sperm to withstand osmotic shock during cryopreservation. Finally, potential aims for future research on cryodamage and cryotolerance are proposed, which might be crucial to minimise the side-effects of cryopreservation and to make it a more advantageous strategy for boar sperm preservation.

Aquaporins in colorectal cancer: exploring their role in tumorigenesis, metastasis, and drug response

Aquaporins (AQPs) are small, integral proteins facilitating water transport across plasma cell membranes in response to osmotic gradients. This family has 13 unique members (AQP0-12), which can also transport glycerol, urea, gases, and other salute small molecules. AQPs play a crucial role in the regulation of different cellular processes, including metabolism, migration, immunity, barrier function, and angiogenesis. These proteins are found to aberrantly overexpress in various cancers, including colorectal cancer (CRC). Growing evidence has explored AQPs as a potential diagnostic biomarker and therapeutic target in different cancers. However, there is no comprehensive review compiling the available information on the crucial role of AQPs in the context of colorectal cancer. This review highlights the significance of AQPs as the biomarker and regulator of tumor cells metabolism. In addition, the proliferation, angiogenesis, and metastasis of tumor cells related to AQPs expression as well as function are discussed. Understanding the AQPs prominent role in chemotherapy resistance is of great importance clinically.

The impact of phospholipids with high transition temperature to enhance redox-sensitive liposomal doxorubicin efficacy in colon carcinoma model

In this study, we have developed a redox-sensitive (RS) liposomal doxorubicin formulation by incorporating 10,10'-diselanediylbis decanoic acid (DDA) organoselenium compound as the RS moiety. Hence, several RS liposomal formulations were prepared by using DOPE, HSPC, DDA, mPEG2000-DSPE, and cholesterol. In situ drug loading using a pH gradient and citrate complex yielded high drug to lipid ratio and encapsulation efficiency (100%) for RS liposomes. Liposomal formulations were characterized in terms of size, surface charge and morphology, drug loading, release properties, cell uptake and cytotoxicity, as well as therapeutic efficacy in BALB/c mice bearing C26 tumor cells. The formulations showed an average particle size of 200 nm with narrow size distributions (PDI < 0.3), and negative surface charges varying from -6 mV to -18.6 mV. Our study confirms that the presence of the DDA compound in liposomes is highly sensitive to hydrogen peroxide at 0.1% w/v, resulting in a significant burst release of up to 40%. The in vivo therapeutic efficacy study in BALB/c mice bearing C26 colon carcinoma confirmed the promising function of RS liposomes in the tumor microenvironment which led to a prolonged median survival time (MST). The addition of hydrogenated soy phosphatidylcholine (HSPC) with a high transition temperature (Tm: 52-53.5°C) extended the MST of our 3-component formulation of F14 (DOPE/HSPC/DDA) to 60 days in comparison to Caelyx (PEGylated liposomal Dox), which is not RS-sensitive (39 days). Overall, HSPC liposomes bearing RS-sensitive moiety enhanced therapeutic efficacy against colon cancer in vitro and in vivo. This achievement unequivocally underscores the criticality of high-TM phospholipids, particularly HSPC, in significantly enhancing liposome stability within the bloodstream. In addition, RS liposomes enable the on-demand release of drugs, leveraging the redox environment of tumor cells, thereby augmenting the efficacy of the formulation.

Intricate balance of dually-localized catalase modulates infectivity of Leptomonas seymouri (Kinetoplastea: Trypanosomatidae)

Nearly all aerobic organisms are equipped with catalases, powerful enzymes scavenging hydrogen peroxide and facilitating defense against harmful reactive oxygen species. In trypanosomatids, this enzyme was not present in the common ancestor, yet it had been independently acquired by different lineages of monoxenous trypanosomatids from different bacteria at least three times. This observation posited an obvious question: why was catalase so "sought after" if many trypanosomatid groups do just fine without it? In this work, we analyzed subcellular localization and function of catalase in Leptomonas seymouri. We demonstrated that this enzyme is present in the cytoplasm and a subset of glycosomes, and that its cytoplasmic retention is H2O2-dependent. The ablation of catalase in this parasite is not detrimental in vivo, while its overexpression resulted in a substantially higher parasite load in the experimental infection of Dysdercus peruvianus. We propose that the capacity of studied flagellates to modulate the catalase activity in the midgut of its insect host facilitates their development and protects them from oxidative damage at elevated temperatures.

Effect of hypoxia on aquaporins and hepatobiliary transport systems in human hepatic cells

OBJECTIVES

Hepatic ischemia and hypoxia are accompanied by reduced bile flow, biliary sludge and cholestasis. Hepatobiliary transport systems, nuclear receptors and aquaporins were studied after hypoxia and reoxygenation in human hepatic cells.

METHODS

Expression of Aquaporin 8 (AQP8), Aquaporin 9 (AQP9), Pregnane X receptor (PXR), Farnesoid X receptor (FXR), Organic anion transporting polypeptide 1 (OATP1), and the Multidrug resistance-associated protein 4 (MRP4) were investigated in induced pluripotent stem cells (iPSCs) derived hepatic cells and the immortalized hepatic line HepG2. HepG2 was subjected to combined oxygen and glucose deprivation for 4 h followed by reoxygenation.

RESULTS

Expression of AQP8 and AQP9 increased during differentiation in iPSC-derived hepatic cells. Hypoxia did not alter mRNA levels of AQP8, but reoxygenation caused a marked increase in AQP8 mRNA expression. While expression of OATP1 had a transient increase during reoxygenation, MRP4 showed a delayed downregulation. Knock-down of FXR did not alter the expression of AQP8, AQP9, MRP4, or OATP1. Post-hypoxic protein levels of AQP8 were reduced after 68 h of reoxygenation compared to normoxic controls.

CONCLUSIONS

Post-transcriptional mechanisms rather than reduced transcription cause reduction in AQP8 protein concentration after hypoxia-reoxygenation in hepatic cells. Expression patterns differed between hepatobiliary transport systems during hypoxia and reoxygenation.

IMPACT

Expression of AQP8 and AQP9 increased during differentiation in induced pluripotent stem cells. Expression of hepatobiliary transporters varies during hypoxia and reoxygenation. Post-hypoxic protein levels of AQP8 were reduced after 68 h of reoxygenation. Post-transcriptional mechanisms rather than reduced transcription cause reduction in AQP8 protein concentration after hypoxia-reoxygenation in hepatic cells. Hypoxia and reoxygenation may affect aquaporins in hepatic cells and potentially affect bile composition.

Trace metals in the teleost fish gill: biological roles, uptake regulation, and detoxification mechanisms

In fish, the gill plays a vital role in regulating the absorption of trace metals and is also highly susceptible to metal toxicity. Trace metals such as iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn) are involved in various catalytic activities and molecular binding within the gill, thereby supporting a range of physiological processes in this organ. While beneficial at normal levels, these metals can become toxic when present in excess. Conversely, nonessential metals like cadmium (Cd) and lead (Pb) can gain entry into gill cells through similar metal transport pathways, potentially interfering with various cellular processes. The transepithelial transport of these metals across the gill epithelium is governed by a variety of metal transport and metal binding proteins. These include the Cu transporter 1 (CTR1), divalent metal transporter 1 (DMT1), and members of the Zrt-/Irt-like protein (ZIP) and zinc transport (ZnT) families. Additionally, some of these metals can compete with major ions (e.g., calcium, sodium) for absorption sites in the gill. This complex crosstalk suggests an interdependent mechanism that balances metal uptake to meet physiological needs while preventing excessive accumulation. In this article, I review the roles of trace metals in proteins/enzymes that support the different functions in the gill of teleost fish. I also discuss current understanding of the pathways involved in regulating the branchial uptake of metals and their influence on ionic regulation, and the potential detoxification mechanisms in the gill. Finally, I summarize knowledge gaps and potential areas for further investigation.

ER-GUARD: an evolutionarily conserved antioxidant defense system at ER membranes

Oxidative protein folding in the endoplasmic reticulum (ER) is essential for all eukaryotic cells yet generates hydrogen peroxide (H2O2), a reactive oxygen species (ROS). The ER-transmembrane protein that provides reducing equivalents to ER and guards the cytosol for antioxidant defense remains unidentified. Here we combine AlphaFold2-based and functional reporter screens in C. elegans to identify a previously uncharacterized and evolutionarily conserved protein ERGU-1 that fulfills these roles. Deleting C. elegans ERGU-1 causes excessive H2O2 and transcriptional gene up-regulation through SKN-1, homolog of mammalian antioxidant master regulator NRF2. ERGU-1 deficiency also impairs organismal reproduction and behaviors. Both C. elegans and human ERGU-1 proteins localize to ER membranes and form network reticulum structures. We name this system ER-GUARD, Endoplasmic Reticulum Guardian Aegis of Redox Defense. Human and Drosophila homologs of ERGU-1 can rescue C. elegans mutant phenotypes, demonstrating evolutionarily ancient and conserved functions. Together, our results reveal an ER-membrane-specific protein machinery and defense-net system ER-GUARD for peroxide detoxification and suggest a previously unknown but conserved pathway for antioxidant defense in animal cells.

Peroxiporins in Triple-Negative Breast Cancer: Biomarker Potential and Therapeutic Perspectives

Triple-negative breast cancer (TNBC) remains one of the most challenging subtypes since it is initially characterized by the absence of specific biomarkers and corresponding targeted therapies. Advances in methodology, translational informatics, genomics, and proteomics have significantly contributed to the identification of therapeutic targets. The development of innovative treatments, such as antibody-drug conjugates and immune checkpoint inhibitors, alongside chemotherapy, has now become the standard of care. However, the quest for biomarkers defining therapy outcomes is still ongoing. Peroxiporins, which comprise a subgroup of aquaporins, which are membrane pores facilitating the transport of water, glycerol, and hydrogen peroxide, have emerged as potential biomarkers for therapy response. Research on peroxiporins reveals their involvement beyond traditional channeling activities, which is also reflected in their cellular localization and roles in cellular signaling pathways. This research on peroxiporins provides fresh insights into the mechanisms of therapy resistance in tumors, offering potential avenues for predicting treatment outcomes and tailoring successful TNBC therapies.

Reactivity of Zinc Fingers in Oxidizing Environments: Insight from Molecular Models Through Activation Strain Analysis

The reactivity of Zn2+ tetrahedral complexes with H2O2 was investigated in silico, as a first step in their disruption process. The substrates were chosen to represent the cores of three different zinc finger protein motifs, i. e., a Zn2+ ion coordinated to four cysteines (CCCC), to three cysteines and one histidine (CCCH), and to two cysteines and two histidines (CCHH). The cysteine and histidine ligands were further simplified to methyl thiolate and imidazole, respectively. H2O2 was chosen as an oxidizing agent due to its biological role as a metabolic product and species involved in signaling processes. The mechanism of oxidation of a coordinated cysteinate to sulfenate-κS and the trends for the different substrates were rationalized through activation strain analysis and energy decomposition analysis in the framework of scalar relativistic Density Functional Theory (DFT) calculations at ZORA-M06/TZ2P ae // ZORA-BLYP-D3(BJ)/TZ2P. CCCC is oxidized most easily, an outcome explained considering both electrostatic and orbital interactions. The isomerization to sulfenate-κO was attempted to assess whether this step may affect the ligand dissociation; however, it was found to introduce a kinetic barrier without improving the energetics of the dissociation. Lastly, ligand exchange with free thiolates and selenolates was investigated as a trigger for ligand dissociation, possibly leading to metal ejection; molecular docking simulations also support this hypothesis.

Aquaporins: a vital nexus in H2O2-gasotransmitter signaling

Land plants have evolved with a complex mechanism of water uptake facilitated by the activity of aquaporins under normal and challenging environments. However, we lack a clear understanding of its interactions with reactive oxygen species, particularly hydrogen peroxide (H2O2) and the gasotransmitters nitric oxide (NO) and hydrogen sulfide (H2S), under oxidative stress. Here, we assess the crosstalk of aquaporin function, H2O2 homeostasis, and NO-H2S signaling in plants and provide a computational prediction of cysteine-based oxidative post-translational modifications (oxiPTMs) in plant aquaporins. We propose that aquaporin activity could be regulated by three major oxiPTMs, S-nitrosation, S-sulfenylation, and persulfidation, mediated by NO, H2O2, and H2S, respectively. Therefore, aquaporins might be key players in the gasotransmitter-mediated long-distance oxidative stress signals in plant cells.

Biomimetic Vesicles with Designer Phospholipids Can Sense Environmental Redox Cues

Cell-like materials that sense environmental cues can serve as next-generation biosensors and help advance the understanding of intercellular communication. Currently, bottom-up engineering of protocell models from molecular building blocks remains a grand challenge chemists face. Herein, we describe giant unilamellar vesicles (GUVs) with biomimetic lipid membranes capable of sensing environmental redox cues. The GUVs employ activity-based sensing through designer phospholipids that are fluorescently activated in response to specific reductive (hydrogen sulfide) or oxidative (hydrogen peroxide) conditions. These synthetic phospholipids are derived from 1,2-dipalmitoyl-rac-glycero-3-phosphocholine and they possess a headgroup with heterocyclic aromatic motifs. Despite their structural deviation from the phosphocholine headgroup, the designer phospholipids (0.5-1.0 mol %) mixed with natural lipids can vesiculate, and the resulting GUVs (7-20 μm in diameter) remain intact over the course of redox sensing. All-atom molecular dynamics simulations gave insight into how these lipids are positioned within the hydrophobic core of the membrane bilayer and at the membrane-water interface. This work provides a purely chemical method to investigate potential redox signaling and opens up new design opportunities for soft materials that mimic protocells.

AQP3 and AQP5 Modulation in Response to Prolonged Oxidative Stress in Breast Cancer Cell Lines

Aquaporins are membrane pores regulating the transport of water, glycerol, and other small molecules across membranes. Among 13 human aquaporins, six have been shown to transport H2O2 and are therefore called peroxiporins. Peroxiporins are implicated in cancer development and progression, partly due to their involvement in H2O2 transport. Oxidative stress is linked to breast cancer development but is also a mechanism of action for conventional chemotherapy. The aim of this study is to investigate the effects of prolonged oxidative stress on Aquaporin 3 (AQP3), Aquaporin 5 (AQP5), and signaling pathways in breast cancer cell lines of different malignancies alongside a non-tumorigenic breast cell line. The prolonged oxidative stress caused responses in viability only in the cancer cell lines, while it affected cell migration in the MCF7 cell line. Changes in the localization of NRF2, a transcription factor involved in oxidative stress response, were observed only in the cancer cell lines, and no effects were recorded on its downstream target proteins. Moreover, the prolonged oxidative stress caused changes in AQP3 and AQP5 expression only in the cancer cell lines, in contrast to their non-malignant counterparts. These results suggest peroxiporins are potential therapeutic targets in cancer treatment. However, further research is needed to elucidate their role in the modulation of therapy response, highlighting the importance of research on this topic.

Advancing Sustainable Malting Practices: Aquaporins as Potential Breeding Targets for Improved Water Uptake during Controlled Germination of Barley (Hordeum vulgare L.)

The conversion of raw barley (Hordeum vulgare L.) to malt requires a process of controlled germination, where the grain is submerged in water to raise the moisture content to >40%. The transmembrane proteins, aquaporins, influence water uptake during the initial stage of controlled germination, yet little is known of their involvement in malting. With the current focus on sustainability, understanding the mechanisms of water uptake and usage during the initial stages of malting has become vital in improving efficient malting practices. In this study, we used quantitative proteomics analysis of two malting barley genotypes demonstrating differing water-uptake phenotypes in the initial stages of malting. Our study quantified 19 transmembrane proteins from nine families, including seven distinct aquaporin isoforms, including the plasma intrinsic proteins (PIPs) PIP1;1, PIP2;1, and PIP2;4 and the tonoplast intrinsic proteins (TIPs) TIP1;1, TIP2;3, TIP3;1, and TIP3;2. Our findings suggest that the presence of TIP1;1, TIP3;1, and TIP3;2 in the mature barley grain proteome is essential for facilitating water uptake, influencing cell turgor and the formation of large central lytic vacuoles aiding storage reserve hydrolysis and endosperm modification efficiency. This study proposes that TIP3s mediate water uptake in malting barley grain, offering potential breeding targets for improving sustainable malting practices.

TIP aquaporins in Cyperus esculentus: genome-wide identification, expression profiles, subcellular localizations, and interaction patterns

BACKGROUND

Tonoplast intrinsic proteins (TIPs), which typically mediate water transport across vacuolar membranes, play an essential role in plant growth, development, and stress responses. However, their characterization in tigernut (Cyperus esculentus L.), an oil-bearing tuber plant of the Cyperaceae family, is still in the infancy.

RESULTS

In this study, a first genome-wide characterization of the TIP subfamily was conducted in tigernut, resulting in ten members representing five previously defined phylogenetic groups, i.e., TIP1-5. Although the gene amounts are equal to that present in two model plants Arabidopsis and rice, the group composition and/or evolution pattern were shown to be different. Except for CeTIP1;3 that has no counterpart in both Arabidopsis and rice, complex orthologous relationships of 1:1, 1:2, 1:3, 2:1, and 2:2 were observed. Expansion of the CeTIP subfamily was contributed by whole-genome duplication (WGD), transposed, and dispersed duplications. In contrast to the recent WGD-derivation of CeTIP3;1/-3;2, synteny analyses indicated that TIP4 and - 5 are old WGD repeats of TIP2, appearing sometime before monocot-eudicot divergence. Expression analysis revealed that CeTIP genes exhibit diverse expression profiles and are subjected to developmental and diurnal fluctuation regulation. Moreover, when transiently overexpressed in tobacco leaves, CeTIP1;1 was shown to locate in the vacuolar membrane and function in homo/heteromultimer, whereas CeTIP2;1 is located in the cell membrane and only function in heteromultimer. Interestingly, CeTIP1;1 could mediate the tonoplast-localization of CeTIP2;1 via protein interaction, implying complex regulatory patterns.

CONCLUSIONS

Our findings provide a global view of CeTIP genes, which provide valuable information for further functional analysis and genetic improvement through manipulating key members in tigernut.

AQP8 Modulates Mitochondrial H2O2 Transport to Influence Glioma Proliferation

BACKGROUND

Aquaporin-8 (AQP8) is involved in impacting glioma proliferation and can effect tumour growth by regulating Intracellular reactive oxygen species (ROS) signalling levels. In addition to transporting H2O2, AQP8 has been shown to affect ROS signaling, but evidence is lacking in gliomas. In this study, we aimed to investigate how AQP8 affects ROS signaling in gliomas.

MATERIALS AND METHODS

We constructed A172 and U251 cell lines with AQP8 knockdown and AQP8 rescue by CRISPR/Cas9 technology and overexpression of lentiviral vectors. We used CCK-8 and flow cytometry to test cell proliferation and cycle, immunofluorescence and Mito-Tracker CMXRos to observe the distribution of AQP8 expression in glioma cells, Amplex and DHE to study mitochondria release of H2O2, mitochondrial membrane potential (MMP) and NAD+/NADH ratio to assess mitochondrial function and protein blotting to detect p53 and p21 expression.

RESULT

We found that AQP8 co-localised with mitochondria and that knockdown of AQP8 inhibited the release of H2O2 from mitochondria and led to increased levels of ROS in mitochondria, thereby impairing mitochondrial function. We also discovered that AQP8 knockdown resulted in suppression of cell proliferation and was blocked at the G0/G1 phase with increased expression of mitochondrial ROS signalling-related p53/p21.

CONCLUSIONS

This finding provides further evidence for mechanistic studies of AQP8 as a prospective target for the treatment of gliomas.

Protective roles of peroxiporins AQP0 and AQP11 in human astrocyte and neuronal cell lines in response to oxidative and inflammatory stressors

In addition to aquaporin (AQP) classes AQP1, AQP4 and AQP9 known to be expressed in mammalian brain, our recent transcriptomic analyses identified AQP0 and AQP11 in human cortex and hippocampus at levels correlated with age and Alzheimer's disease (AD) status; however, protein localization remained unknown. Roles of AQP0 and AQP11 in transporting hydrogen peroxide (H2O2) in lens and kidney prompted our hypothesis that up-regulation in brain might similarly be protective. Established cell lines for astroglia (1321N1) and neurons (SHSY5Y, differentiated with retinoic acid) were used to monitor changes in transcript levels for human AQPs (AQP0 to AQP12) in response to inflammation (simulated with 10-100 ng/ml lipopolysaccharide [LPS], 24 h), and hypoxia (5 min N2, followed by 0 to 24 h normoxia). AQP transcripts up-regulated in both 1321N1 and SHSY5Y included AQP0, AQP1 and AQP11. Immunocytochemistry in 1321N1 cells confirmed protein expression for AQP0 and AQP11 in plasma membrane and endoplasmic reticulum; AQP11 increased 10-fold after LPS and AQP0 increased 0.3-fold. In SHSY5Y cells, AQP0 expression increased 0.2-fold after 24 h LPS; AQP11 showed no appreciable change. Proposed peroxiporin roles were tested using melondialdehyde (MDA) assays to quantify lipid peroxidation levels after brief H2O2. Boosting peroxiporin expression by LPS pretreatment lowered subsequent H2O2-induced MDA responses (∼50%) compared with controls; conversely small interfering RNA knockdown of AQP0 in 1321N1 increased lipid peroxidation (∼17%) after H2O2, with a similar trend for AQP11 siRNA. Interventions that increase native brain peroxiporin activity are promising as new approaches to mitigate damage caused by aging and neurodegeneration.

Ultra-fast genetically encoded sensor for precise real-time monitoring of physiological and pathophysiological peroxide dynamics

Hydrogen Peroxide (H2O2) is a central oxidant in redox biology due to its pleiotropic role in physiology and pathology. However, real-time monitoring of H2O2 in living cells and tissues remains a challenge. We address this gap with the development of an optogenetic hydRogen perOxide Sensor (oROS), leveraging the bacterial peroxide binding domain OxyR. Previously engineered OxyR-based fluorescent peroxide sensors lack the necessary sensitivity and response speed for effective real-time monitoring. By structurally redesigning the fusion of Escherichia coli (E. coli) ecOxyR with a circularly permutated green fluorescent protein (cpGFP), we created a novel, green-fluorescent peroxide sensor oROS-G. oROS-G exhibits high sensitivity and fast on-and-off kinetics, ideal for monitoring intracellular H2O2 dynamics. We successfully tracked real-time transient and steady-state H2O2 levels in diverse biological systems, including human stem cell-derived neurons and cardiomyocytes, primary neurons and astrocytes, and mouse brain ex vivo and in vivo. These applications demonstrate oROS's capabilities to monitor H2O2 as a secondary response to pharmacologically induced oxidative stress and when adapting to varying metabolic stress. We showcased the increased oxidative stress in astrocytes via Aβ-putriscine-MAOB axis, highlighting the sensor's relevance in validating neurodegenerative disease models. Lastly, we demonstrated acute opioid-induced generation of H2O2 signal in vivo which highlights redox-based mechanisms of GPCR regulation. oROS is a versatile tool, offering a window into the dynamic landscape of H2O2 signaling. This advancement paves the way for a deeper understanding of redox physiology, with significant implications for understanding diseases associated with oxidative stress, such as cancer, neurodegenerative, and cardiovascular diseases.

Quorum sensing signal autoinducer-2 promotes hydrogen peroxide degradation in water by Gram-positive bacteria

Hydrogen peroxide is widely used to remedy bacterial and parasitic infections, but its excessive use will cause severe damage to aquatic animals. Moreover, there is no safe, efficient and low-cost method to degrade residual hydrogen peroxide in water. Here we developed a hydrogen peroxide removal mechanism by which autoinducer-2 (AI-2), a quorum sensing signal molecule that can promote the hydrogen peroxide degradation by Gram-positive bacteria. Here, we investigated the promotion effect of AI-2 on hydrogen peroxide degradation by Deinococcus sp. Y35 and the response of the antioxidant system. We further sought to understand the key mechanism underlying the promotion effect of AI-2 on hydrogen peroxide degradation is that, AI-2 contributed to the resistance of strain Y35 to oxidative stress induced by hydrogen peroxide, and altered membrane permeability of strain Y35 that allowed more hydrogen peroxide to enter bacterial cells and be degraded. Additionally, AI-2 can also encourage multiple Gram-positive bacteria to degrade hydrogen peroxide. Accordingly, our study serves as a reference for the regulation mechanism of the signal molecule AI-2 and provides the development of new strategies for hydrogen peroxide degradation.

Aquaporin-8 promotes human dermal fibroblasts to counteract hydrogen peroxide-induced oxidative damage: A novel target for management of skin aging

The skin is subjected to various external factors that contribute to aging including oxidative stress from hydrogen peroxide (H2O2). This study investigated the distribution of aquaporin-8 (AQP8), a protein that transports H2O2 across biological membranes, in skin cells, and its effects in mitigating H2O2-induced oxidative damage. Human dermal fibroblasts were treated with increasing concentrations of H2O2 to evaluate oxidative damage. Cell viability, reactive oxygen species (ROS) generation, and the expression of specific genes associated with skin aging (IL-10, FPR2, COL1A1, KRT19, and Aggrecan) were evaluated and AQP8 expression was assessed via quantitative polymerase chain reaction and western blotting. Small-interfering RNA was used to silence the AQP8 gene and evaluate its significance. The results show that H2O2 treatment reduces cell viability and increases ROS generation, leading to oxidative damage that affects the expression of target molecules. Interestingly, H2O2-treated cells exhibit high levels of AQP8 expression and gene silencing of AQP8 reverses high levels of ROS and low levels of COL1A1, KRT19, and Aggrecan expression in stressed cells, indicating that AQP8 plays a vital role in preventing oxidative damage and consequent aging. In conclusion, AQP8 is upregulated in human dermal fibroblasts during H2O2-induced oxidative stress and may help prevent oxidative damage and aging. These findings suggest that AQP8 could be a potential therapeutic target for skin aging. Further research is necessary to explore the feasibility of using AQP8 as a preventive or therapeutic strategy for maintaining skin health.

Structure-guided engineering of a fast genetically encoded sensor for real-time H2O2 monitoring

Hydrogen Peroxide (H2O2) is a central oxidant in redox biology due to its pleiotropic role in physiology and pathology. However, real-time monitoring of H2O2 in living cells and tissues remains a challenge. We address this gap with the development of an optogenetic hydRogen perOxide Sensor (oROS), leveraging the bacterial peroxide binding domain OxyR. Previously engineered OxyR-based fluorescent peroxide sensors lack the necessary sensitivity or response speed for effective real-time monitoring. By structurally redesigning the fusion of Escherichia coli (E. coli) ecOxyR with a circularly permutated green fluorescent protein (cpGFP), we created a novel, green-fluorescent peroxide sensor oROS-G. oROS-G exhibits high sensitivity and fast on-and-off kinetics, ideal for monitoring intracellular H2O2 dynamics. We successfully tracked real-time transient and steady-state H2O2 levels in diverse biological systems, including human stem cell-derived neurons and cardiomyocytes, primary neurons and astrocytes, and mouse neurons and astrocytes in ex vivo brain slices. These applications demonstrate oROS's capabilities to monitor H2O2 as a secondary response to pharmacologically induced oxidative stress, G-protein coupled receptor (GPCR)-induced cell signaling, and when adapting to varying metabolic stress. We showcased the increased oxidative stress in astrocytes via Aβ-putriscine-MAOB axis, highlighting the sensor's relevance in validating neurodegenerative disease models. oROS is a versatile tool, offering a window into the dynamic landscape of H2O2 signaling. This advancement paves the way for a deeper understanding of redox physiology, with significant implications for diseases associated with oxidative stress, such as cancer, neurodegenerative disorders, and cardiovascular diseases.

The architecture of redox microdomains: Cascading gradients and peroxiredoxins' redox-oligomeric coupling integrate redox signaling and antioxidant protection

In the cytosol of human cells under low oxidative loads, hydrogen peroxide is confined to microdomains around its supply sites, due to its fast consumption by peroxiredoxins. So are the sulfenic and disulfide forms of the 2-Cys peroxiredoxins, according to a previous theoretical analysis [Travasso et al., Redox Biology 15 (2017) 297]. Here, an extended reaction-diffusion model that for the first time considers the differential properties of human peroxiredoxins 1 and 2 and the thioredoxin redox cycle predicts important new aspects of the dynamics of redox microdomains. The peroxiredoxin 1 sulfenates and disulfides are more localized than the corresponding peroxiredoxin 2 forms, due to the former peroxiredoxin's faster resolution step. The thioredoxin disulfides are also localized. As the H2O2 supply rate (vsup) approaches and then surpasses the maximal rate of the thioredoxin/thioredoxin reductase system (V), these concentration gradients become shallower, and then vanish. At low vsup the peroxiredoxin concentration determines the H2O2 concentrations and gradient length scale, but as vsup approaches V, the thioredoxin reductase activity gains influence. A differential mobility of peroxiredoxin disulfide dimers vs. reduced decamers enhances the redox polarity of the cytosol: as vsup approaches V, reduced decamers are preferentially retained far from H2O2 sources, attenuating the local H2O2 buildup. Substantial total protein concentration gradients of both peroxiredoxins emerge under these conditions, and the concentration of reduced peroxiredoxin 1 far from the H2O2 sources even increases with vsup. Altogether, the properties of 2-Cys peroxiredoxins and thioredoxin are such that localized H2O2 supply induces a redox and functional polarization between source-proximal regions (redox microdomains) that facilitate peroxiredoxin-mediated signaling and distal regions that maximize antioxidant protection.

A new method to measure aquaporin-facilitated membrane diffusion of hydrogen peroxide and cations in plant suspension cells

Plant aquaporins (AQPs) facilitate the membrane diffusion of water and small solutes, including hydrogen peroxide (H2 O2 ) and, possibly, cations, essential signalling molecules in many physiological processes. While the determination of the channel activity generally depends on heterologous expression of AQPs in Xenopus oocytes or yeast cells, we established a genetic tool to determine whether they facilitate the diffusion of H2 O2 through the plasma membrane in living plant cells. We designed genetic constructs to co-express the fluorescent H2 O2 sensor HyPer and AQPs, with expression controlled by a heat shock-inducible promoter in Nicotiana tabacum BY-2 suspension cells. After induction of ZmPIP2;5 AQP expression, a HyPer signal was recorded when the cells were incubated with H2 O2 , suggesting that ZmPIP2;5 facilitates H2 O2 transmembrane diffusion; in contrast, the ZmPIP2;5W85A mutated protein was inactive as a water or H2 O2 channel. ZmPIP2;1, ZmPIP2;4 and AtPIP2;1 also facilitated H2 O2 diffusion. Incubation with abscisic acid and the elicitor flg22 peptide induced the intracellular H2 O2 accumulation in BY-2 cells expressing ZmPIP2;5. We also monitored cation channel activity of ZmPIP2;5 using a novel fluorescent photo-switchable Li+ sensor in BY-2 cells. BY-2 suspension cells engineered for inducible expression of AQPs as well as HyPer expression and the use of Li+ sensors constitute a powerful toolkit for evaluating the transport activity and the molecular determinants of PIPs in living plant cells.

Reactive oxygen species signaling in melatonin-mediated plant stress response

Reactive oxygen species (ROS) are crucial signaling molecules in plants that play multifarious roles in prompt response to environmental stimuli. Despite the classical thoughts that ROS are toxic when accumulate in excess, recent advances in plant ROS signaling biology reveal that ROS participate in biotic and abiotic stress perception, signal integration, and stress-response network activation, hence contributing to plant defense and stress tolerance. ROS production, scavenging and transport are fine-tuned by plant hormones and stress-response signaling pathways. Crucially, the emerging plant hormone melatonin attenuates excessive ROS accumulation under stress, whereas ROS signaling mediates melatonin-induced plant developmental response and stress tolerance. In particular, RESPIRATORY BURST OXIDASE HOMOLOG (RBOH) proteins responsible for apoplastic ROS generation act downstream of melatonin to mediate stress response. In this review, we discuss promising developments in plant ROS signaling and how ROS might mediate melatonin-induced plant resilience to environmental stress.

An Overview of Reactive Oxygen Species Damage Occurring during In Vitro Bovine Oocyte and Embryo Development and the Efficacy of Antioxidant Use to Limit These Adverse Effects

The in vitro production (IVP) of bovine embryos has gained popularity worldwide and in recent years and its use for producing embryos from genetically elite heifers and cows has surpassed the use of conventional superovulation-based embryo production schemes. There are, however, several issues with the IVP of embryos that remain unresolved. One limitation of special concern is the low efficiency of the IVP of embryos. Exposure to reactive oxygen species (ROS) is one reason why the production of embryos with IVP is diminished. These highly reactive molecules are generated in small amounts through normal cellular metabolism, but their abundances increase in embryo culture because of oocyte and embryo exposure to temperature fluctuations, light exposure, pH changes, atmospheric oxygen tension, suboptimal culture media formulations, and cryopreservation. When uncontrolled, ROS produce detrimental effects on the structure and function of genomic and mitochondrial DNA, alter DNA methylation, increase lipid membrane damage, and modify protein activity. Several intrinsic enzymatic pathways control ROS abundance and damage, and antioxidants react with and reduce the reactive potential of ROS. This review will focus on exploring the efficiency of supplementing several of these antioxidant molecules on oocyte maturation, sperm viability, fertilization, and embryo culture.

Salicylic acid alleviates the effects of cadmium and drought stress by regulating water status, ions, and antioxidant defense in Pterocarya fraxinifolia

Introduction

Pterocarya fraxinifolia (Poiret) Spach (Caucasian wingnut, Juglandaceae) is a relict tree species, and little is known about its tolerance to abiotic stress factors, including drought stress and heavy metal toxicity. In addition, salicylic acid (SA) has been shown to have a pivotal role in plant responses to biotic and abiotic stresses.

Methods

The current study is focused on evaluating the impact of foliar application of SA in mediating Caucasian wingnut physiological and biochemical responses, including growth, relative water content (RWC), osmotic potential (Ψs), quantum yield (Fv/Fm), electrolyte leakage, lipid peroxidation, hydrogen peroxide, and antioxidant enzymes, to cadmium (Cd; 100 µM) and drought stress, as well as their interaction. Moreover, the antioxidant activity (e.g., ascorbate peroxidase, catalase, glutathione reductase, peroxidase, and superoxide dismutase activities) of the stressed trees was investigated. The study was conducted on 6-month-old seedlings under controlled environmental conditions in a greenhouse for 3 weeks.

Results and discussion

Leaf length, RWC, Ψs, and Fv/Fm were decreased under all treatments, although the effect of drought stress was the most pronounced. An efficient antioxidant defense mechanism was detected in Caucasian wingnut. Moreover, SA-treated Caucasian wingnut plants had lower lipid peroxidation, as one of the indicators of oxidative stress, when compared to non-SA-treated groups, suggesting the tolerance of this plant to Cd stress, drought stress, and their combination. Cadmium and drought stress also changed the ion concentrations in Caucasian wingnut, causing excessive accumulation of Cd in leaves. These results highlight the beneficial function of SA in reducing the negative effects of Cd and drought stress on Caucasian wingnut plants.

Melatonin enhances captopril mediated cardioprotective effects and improves mitochondrial dynamics in male Wistar rats with chronic heart failure

Mitochondrial dysfunction is a recent emerging research scope that proved to be involved in many cardiovascular diseases culminating in chronic heart failure (CHF), which remains one of the primary causes of morbidity and mortality. This study investigated the added cardio-protective effects of exogenous melatonin administration to conventional captopril therapy in isoproterenol (ISO) exposed rats with CHF. Five groups of Wistar rats were recruited; (I): Control group, (II): (ISO group), (III): (ISO + captopril group), (IV): (ISO + melatonin group) and (V): (ISO + melatonin/captopril group). Cardiac function parameters and some oxidant, inflammatory and fibrotic markers were investigated. Moreover; mRNA expression of mitochondrial mitophagy [parkin & PTEN induced kinase 1 (PINK1)], biogenesis [Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)], fusion [mitofusin 2 (Mfn2)] and fission [dynamin-related protein 1 (DRP-1)] parameters in rat's myocardium were evaluated. Rats' myocardium was histo-pathologically and immunohistochemically evaluated for Beclin1 and Sirt3 expression. The present study revealed that captopril and melatonin ameliorated cardiac injury, oxidative stress biomarkers, and pro-inflammatory cytokines in ISO-exposed rats. These protective effects could be attributed to mitochondrial dynamic proteins control (i.e. enhanced the mRNA expression of parkin, PINK1, PGC-1α and Mfn2, while reduced DRP-1 mRNA expression). Also, Beclin1 and Sirt3 cardiac immunoreactivity were improved. Combined captopril and melatonin therapy showed a better response than either agent alone. Melatonin enhanced myocardial mitochondrial dynamics and Sirt3 expression in CHF rats and may represent a promising upcoming therapy added to conventional heart failure treatment.

Calcium Signaling and the Response to Heat Shock in Crop Plants

Climate change and the increasing frequency of high temperature (HT) events are significant threats to global crop yields. To address this, a comprehensive understanding of how plants respond to heat shock (HS) is essential. Signaling pathways involving calcium (Ca2+), a versatile second messenger in plants, encode information through temporal and spatial variations in ion concentration. Ca2+ is detected by Ca2+-sensing effectors, including channels and binding proteins, which trigger specific cellular responses. At elevated temperatures, the cytosolic concentration of Ca2+ in plant cells increases rapidly, making Ca2+ signals the earliest response to HS. In this review, we discuss the crucial role of Ca2+ signaling in raising plant thermotolerance, and we explore its multifaceted contributions to various aspects of the plant HS response (HSR).

A Small-Molecule Approach to Bypass In Vitro Selection of New Aptamers: Designer Pre-Ligands Turn Baby Spinach into Sensors for Reactive Inorganic Targets

Fluorescent light-up aptamer (FLAP) systems are promising biosensing platforms that can be genetically encoded. Here, we describe how a single FLAP that works with specific organic ligands can detect multiple, structurally unique, non-fluorogenic, and reactive inorganic targets. We developed 4-O-functionalized benzylidene imidazolinones as pre-ligands with suppressed fluorescent binding interactions with the RNA aptamer Baby Spinach. Inorganic targets, hydrogen sulfide (H2S) or hydrogen peroxide (H2O2), can specifically convert these pre-ligands into the native benzylidene imidazolinones, and thus be detected with Baby Spinach. Adaptation of this approach to live cells opened a new opportunity for top-down construction of whole-cell sensors: Escherichia coli transformed with a Baby Spinach-encoding plasmid and incubated with pre-ligands generated fluorescence in response to exogenous H2S or H2O2. Our approach eliminates the requirement of in vitro selection of a new aptamer sequence for molecular target detection, allows for the detection of short-lived targets, thereby advancing FLAP systems beyond their current capabilities. Leveraging the functional group reactivity of small molecules can lead to cell-based sensors for inorganic molecular targets, exploiting a new synergism between synthetic organic chemistry and synthetic biology.

Food Polyphenols as Preventive Medicine

Reactive oxygen species (ROS) are the initiators in foods and in the stomach of oxidized dietary lipids, proteins, and lipid-oxidation end-products (ALEs), inducing in humans the development of several chronic diseases and cancer. Epidemiological, human clinical and animal studies supported the role of dietary polyphenols and derivatives in prevention of development of such chronic diseases. There is much evidence that polyphenols/derivatives at the right timing and concentration, which is critical, acts mostly in the aerobic stomach and generally in the gastrointestinal tract as reducing agents, scavengers of free radicals, trappers of reactive carbonyls, modulators of enzyme activity, generators of beneficial gut microbiota and effectors of cellular signaling. In the blood system, at low concentration, they act as generators of electrophiles and low concentration of H2O2, acting mostly as cellular signaling, activating the PI3K/Akt-mediated Nrf2/eNOS pathways and inhibiting the inflammatory transcription factor NF-κB, inducing the cells, organs and organism for eustress, adaptation and surviving.

Intestinal polyphenol antioxidant activity involves redox signaling mechanisms facilitated by aquaporin activity

Ascertaining whether dietary polyphenols evoke an antioxidant or prooxidant activity, which translates to a functional role required to maintain intestinal cell homeostasis continues to be an active and controversial area of research for food chemists and biochemists alike. We have proposed that the paradoxical function of polyphenols to autoxidize to generate H2O2 is a required first step in the capacity of some plant phenolics to function as intracellular antioxidants. This is based on the fact that cell redox homeostasis is achieved by a balance between H2O2 formation and subsequent outcomes of antioxidant systems function. Maintaining optimal extracellular and intracellular H2O2 concentrations is required for cell survival, since low levels are important to upregulate endogenous antioxidant capacity; whereas, concentrations that go beyond homeostatic control typically result in an inflammatory response, growth arrest, or eventual cell death. Aquaporins (AQPs) are a family of water channel membrane proteins that facilitate cellular transportation of water and other small molecule-derived solutes, such as H2O2, in all organisms. In the intestine, AQPs act as gatekeepers to regulate intracellular uptake of H2O2, generated from extracellular polyphenol autoxidation, thus enabling an intracellular cell signaling responses to mitigate onset of oxidative stress and intestinal inflammation. In this review, we highlight the potential role of AQPs to control important underlying mechanisms that define downstream regulation of intestinal redox homeostasis, specifically. It has been established that polyphenols that undergo oxidation to the quinone form, resulting in subsequent adduction to a thiol group on Keap1-Nrf2 complex, trigger Nrf2 activation and a cascade of indirect intracellular antioxidant effects. Here, we propose a similar mechanism that involves H2O2 generated from specific dietary polyphenols with a predisposition to undergo autoxidation. The ultimate bioactivity is regulated and expressed by AQP membrane function and thus, by extension, represents expression of an intracellular antioxidant chemoprotection mechanism.

ROS: Important factor in plant stem cell fate regulation

Reactive oxygen species (ROS) are initially considered to be toxic byproducts of aerobic metabolic reactions. However, increasing evidence has shown that they have emerged as signaling molecules involved in several basic biological processes. Recent studies highlight the pivotal role of ROS in the maintenance of shoot and root stem cell niche. In this review, we discuss the impact of ROS distribution and their gradients on the stability of the stem cell niches (SCN) in shoot apical meristem (SAM) and root apical meristem (RAM) by determining the balance between stemness and differentiation. We also summarize several important transcription factors that are involved in the regulation of ROS balance in SAM and RAM, regulating key enzymes in ROS metabolism, especially SOD and peroxidase. ROS are also tightly interconnected with phytohormones in the control of the stem cell fate. Besides, ROS are also important regulators of the cell cycle in controlling the size of the stem cells. Understanding the regulation mechanisms of ROS production, polarization gradient distribution, homeostasis, and downstream signal transduction in cells will open exciting new perspectives for plant developmental biology.

The resolution of phagosomes

Phagocytosis is a fundamental immunobiological process responsible for the removal of harmful particulates. While the number of phagocytic events achieved by a single phagocyte can be remarkable, exceeding hundreds per day, the same phagocytic cells are relatively long-lived. It should therefore be obvious that phagocytic meals must be resolved in order to maintain the responsiveness of the phagocyte and to avoid storage defects. In this article, we discuss the mechanisms involved in the resolution process, including solute transport pathways and membrane traffic. We describe how products liberated in phagolysosomes support phagocyte metabolism and the immune response. We also speculate on mechanisms involved in the redistribution of phagosomal metabolites back to circulation. Finally, we highlight the pathologies owed to impaired phagosome resolution, which range from storage disorders to neurodegenerative diseases.

All-optical spatiotemporal mapping of ROS dynamics across mitochondrial microdomains in situ

Hydrogen peroxide (H2O2) functions as a second messenger to signal metabolic distress through highly compartmentalized production in mitochondria. The dynamics of reactive oxygen species (ROS) generation and diffusion between mitochondrial compartments and into the cytosol govern oxidative stress responses and pathology, though these processes remain poorly understood. Here, we couple the H2O2 biosensor, HyPer7, with optogenetic stimulation of the ROS-generating protein KillerRed targeted into multiple mitochondrial microdomains. Single mitochondrial photogeneration of H2O2 demonstrates the spatiotemporal dynamics of ROS diffusion and transient hyperfusion of mitochondria due to ROS. This transient hyperfusion phenotype required mitochondrial fusion but not fission machinery. Measurement of microdomain-specific H2O2 diffusion kinetics reveals directionally selective diffusion through mitochondrial microdomains. All-optical generation and detection of physiologically-relevant concentrations of H2O2 between mitochondrial compartments provide a map of mitochondrial H2O2 diffusion dynamics in situ as a framework to understand the role of ROS in health and disease.

Global transcriptome profiling reveals root- and leaf-specific responses of barley (Hordeum vulgare L.) to H2O2

In cereal crops, such as barley (Hordeum vulgare L.), the ability to appropriately respond to environmental cues is an important factor for yield stability and thus for agricultural production. Reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), are key components of signal transduction cascades involved in plant adaptation to changing environmental conditions. H2O2-mediated stress responses include the modulation of expression of stress-responsive genes required to cope with different abiotic and biotic stresses. Despite its importance, knowledge of the effects of H2O2 on the barley transcriptome is still scarce. In this study, we identified global transcriptomic changes induced after application of 10 mM H2O2 to five-day-old barley plants. In total, 1883 and 1001 differentially expressed genes (DEGs) were identified in roots and leaves, respectively. Most of these DEGs were organ-specific, with only 209 DEGs commonly regulated and 37 counter-regulated between both plant parts. A GO term analysis further confirmed that different processes were affected in roots and leaves. It revealed that DEGs in leaves mostly comprised genes associated with hormone signaling, response to H2O2 and abiotic stresses. This includes many transcriptions factors and small heat shock proteins. DEGs in roots mostly comprised genes linked to crucial aspects of H2O2 catabolism and oxidant detoxification, glutathione metabolism, as well as cell wall modulation. These categories include many peroxidases and glutathione transferases. As with leaves, the H2O2 response category in roots contains small heat shock proteins, however, mostly different members of this family were affected and they were all regulated in the opposite direction in the two plant parts. Validation of the expression of the selected commonly regulated DEGs by qRT-PCR was consistent with the RNA-seq data. The data obtained in this study provide an insight into the molecular mechanisms of oxidative stress responses in barley, which might also play a role upon other stresses that induce oxidative bursts.

Aquaporin water channels: roles beyond renal water handling

Aquaporin (AQP) water channels are pivotal to renal water handling and therefore in the regulation of body water homeostasis. However, beyond the kidney, AQPs facilitate water reabsorption and secretion in other cells and tissues, including sweat and salivary glands and the gastrointestinal tract. A growing body of evidence has also revealed that AQPs not only facilitate the transport of water but also the transport of several small molecules and gases such as glycerol, H2O2, ions and CO2. Moreover, AQPs are increasingly understood to contribute to various cellular processes, including cellular migration, adhesion and polarity, and to act upstream of several intracellular and intercellular signalling pathways to regulate processes such as cell proliferation, apoptosis and cell invasiveness. Of note, several AQPs are highly expressed in multiple cancers, where their expression can correlate with the spread of cancerous cells to lymph nodes and alter the response of cancers to conventional chemotherapeutics. These data suggest that AQPs have diverse roles in various homeostatic and physiological systems and may be exploited for prognostics and therapeutic interventions.

Evaluating the antioxidative defense response of selected indoor plants against benzene and formaldehyde

Volatile organic compounds (VOCs) such as formaldehyde and benzene are among the key contributors to indoor air pollution. The current situation of environmental pollution is alarming, especially indoor air pollution is becoming a challenge as affecting plants and humans. VOCs are known to adversely affect indoor plants by causing necrosis and chlorosis. In order to withstand these organic pollutants, plants are naturally equipped with an antioxidative defense system. The current research study aimed to evaluate the combined effect of formaldehyde and benzene on the antioxidative response of selected indoor C3 plants including Chlorophytum comosum, Dracaena mysore, and Ficus longifolia. After the combined application of different levels (0, 0; 2, 2; 2, 4; 4, 2; and 4, 4 ppm) of benzene and formaldehyde respectively, in an airtight glass chamber, the enzymatic and non-enzymatic antioxidants were analyzed. Analysis of total phenolics showed a significant increase (10.72 mg GAE/g) in F. longifolia; C. comosum (9.20 mg GAE/g); and D. mysore (8.74 mg GAE/g) compared to their respective controls as 3.76, 5.39, and 6.07 mg GAE/g. Total flavonoids (724 µg/g) were reported in control plants of F. longifolia which were increased to 1545.72 µg/g from 724 µg/g (in control) followed by 322.66 µg/g in D. mysore (control having 167.11 µg/g). Total carotenoid content also increased in D. mysore (0.67 mg/g) followed by C. comosum (0.63 mg/g) in response to increasing the combined dose compared to their control plants having 0.62 and 0.24 mg/g content. The highest proline content was exhibited by D. mysore (3.66 μg/g) as compared to its respective control plant (1.54 μg/g) under a 4 ppm dose of benzene and formaldehyde. A significant increase in enzymatic antioxidants including total antioxidants (87.89%), catalase (59.21 U/mg of protein), and guaiacol peroxidase (52.16 U/mg of protein) was observed in the D. mysore plant under a combined dose of benzene (2 ppm) and formaldehyde (4 ppm) with respect to their controls. Although experimental indoor plants have been reported to metabolize indoor pollutants, the current findings indicate that the combined application of benzene and formaldehyde is also affecting the physiology of indoor plants as well.

Salicylate and jasmonate intertwine in ROS-triggered chloroplast-to-nucleus retrograde signaling

Plants, being sessile, are frequently exposed to environmental perturbations, affecting their sustenance and survival. In response, distinct inherent mechanisms emerged during plant evolution to deal with environmental stresses. Among various organelles, chloroplast plays an indispensable role in plant cells. Besides providing the site for photosynthesis and biosynthesis of many important primary and secondary metabolites, including hormones, chloroplasts also act as environmental sensors. Any environmental perturbation directly influences the photosynthetic electron transport chain, leading to excess accumulation of reactive oxygen species (ROS), causing oxidative damages to biomolecules in the vicinity. To prevent excess ROS accumulation and the consequent oxidative damages, the chloroplast activates retrograde signaling (RS) pathways to reprogramme nuclear gene expression, defining plant's response to stress. Based on levels and site of ROS accumulation, distinct biomolecules are oxidized, generating specific derivatives that act as genuine signaling molecules, triggering specific RS pathways to instigate distinctive responses, including growth inhibition, acclimation, and programmed cell death. Though various RS pathways independently modulate nuclear gene expression, they also implicate the defense hormone salicylic acid (SA) and oxylipins, including 12-oxo-phytodienoic acid (OPDA) and jasmonic acid (JA), by promoting their biosynthesis and utilizing them for intra- and intercellular communications. Several studies reported the involvement of both hormones in individual RS pathways, but the precise dissection of their activation and participation in a given RS pathway remains an enigma. The present review describes the current understanding of how SA and JA intertwine in ROS-triggered RS pathways. We have also emphasized the future perspectives for elucidating stress specificity and spatiotemporal accumulation of respective hormones in a given RS pathway.

Biochemical and cellular basis of oxidative stress: Implications for disease onset

Cellular oxidation-reduction (redox) systems, which encompass pro- and antioxidant molecules, are integral components of a plethora of essential cellular processes. Any dysregulation of these systems can cause molecular imbalances between the pro- and antioxidant moieties, leading to a state of oxidative stress. Long-lasting oxidative stress can manifest clinically as a variety of chronic illnesses including cancers, neurodegenerative disorders, cardiovascular disease, and metabolic diseases like diabetes. As such, this review investigates the impact of oxidative stress on the human body with emphasis on the underlying oxidants, mechanisms, and pathways. It also discusses the available antioxidant defense mechanisms. The cellular monitoring and regulatory systems that ensure a balanced oxidative cellular environment are detailed. We critically discuss the notion of oxidants as a double-edged sword, being signaling messengers at low physiological concentrations but causative agents of oxidative stress when overproduced. In this regard, the review also presents strategies employed by oxidants including redox signaling and activation of transcriptional programs such as those mediated by the Nrf2/Keap1 and NFk signaling. Likewise, redox molecular switches of peroxiredoxin and DJ-1 and the proteins they regulate are presented. The review concludes that a thorough comprehension of cellular redox systems is essential to develop the evolving field of redox medicine.

Aquaglyceroporins in Human Breast Cancer

Aquaporins are water channels that facilitate passive water transport across cellular membranes following an osmotic gradient and are essential in the regulation of body water homeostasis. Several aquaporins are overexpressed in breast cancer, and AQP1, AQP3 and AQP5 have been linked to spread to lymph nodes and poor prognosis. The subgroup aquaglyceroporins also facilitate the transport of glycerol and are thus involved in cellular metabolism. Transcriptomic analysis revealed that the three aquaglyceroporins, AQP3, AQP7 and AQP9, but not AQP10, are overexpressed in human breast cancer. It is, however, unknown if they are all expressed in the same cells or have a heterogeneous expression pattern. To investigate this, we employed immunohistochemical analysis of serial sections from human invasive ductal and lobular breast cancers. We found that AQP3, AQP7 and AQP9 are homogeneously expressed in almost all cells in both premalignant in situ lesions and invasive lesions. Thus, potential intervention strategies targeting cellular metabolism via the aquaglyceroporins should consider all three expressed aquaglyceroporins, namely AQP3, AQP7 and AQP9.

The Applications and Mechanisms of Superoxide Dismutase in Medicine, Food, and Cosmetics

Superoxide dismutase (SOD) is a class of enzymes that restrict the biological oxidant cluster enzyme system in the body, which can effectively respond to cellular oxidative stress, lipid metabolism, inflammation, and oxidation. Published studies have shown that SOD enzymes (SODs) could maintain a dynamic balance between the production and scavenging of biological oxidants in the body and prevent the toxic effects of free radicals, and have been shown to be effective in anti-tumor, anti-radiation, and anti-aging studies. This research summarizes the types, biological functions, and regulatory mechanisms of SODs, as well as their applications in medicine, food production, and cosmetic production. SODs have proven to be a useful tool in fighting disease, and mimetics and conjugates that report SODs have been developed successively to improve the effectiveness of SODs. There are still obstacles to solving the membrane permeability of SODs and the persistence of enzyme action, which is still a hot spot and difficulty in mining the effect of SODs and promoting their application in the future.

Aquaporin 5 in the eye: Expression, function, and roles in ocular diseases

As a water channel protein, aquaporin 5 (AQP5) is essential for the maintenance of the normal physiological functions of ocular tissues. This review provides an overview of the expression and function of AQP5 in the eye and discusses their role in related eye diseases. Although AQP5 plays a vital role in ocular functions, such as maintaining corneal and lens transparency, regulating water movement, and maintaining homeostasis, some of its functions in ocular tissues are still unclear. Based on the key role of AQP5 in eye function, this review suggests that in the future, eye diseases may be treated by regulating the expression of aquaporin.

Electrostatic Atomized Water Particles Induce Disease Resistance in Muskmelon (Cucumis melo L.) against Postharvest Fruit Rot Caused by Fusarium incarnatum

The postharvest quality of muskmelon can be affected by fruit rot caused by the fungus Fusarium incarnatum, resulting in loss of quality. The utilization of electrostatic atomized water particles (EAWPs) in agriculture applications has been shown to induce disease resistance in plants. Therefore, in this study, we determined the effect of electrostatic atomized water particles (EAWPs) on the disease resistance of muskmelon fruits against postharvest fruit rot caused by F. incarnatum. EAWPs were applied to muskmelon fruits for 0, 30, 60, and 90 min. EAWP-treated muskmelon fruits were inoculated with F. incarnatum, and disease progress was measured. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) of the chitinase (CmCHI) and β-1,3-glucanase (CmGLU) genes of Cucumis melo (muskmelon) was performed for EAWP-treated and -untreated muskmelon fruits. The activities of cell-wall-degrading enzymes (CWDEs), chitinase, and β-1,3-glucanase were also assayed in EAWP-treated and -untreated muskmelon fruits. The results showed that disease progress was limited by EAWP treatment for 30 min prior to pathogen inoculation. Muskmelon fruits treated with EAWPs for 30 min showed an upregulation of CWDE genes, CmCHI and CmGLU, as observed by qRT-PCR, leading to high chitinase and β-1,3-glucanase activities, as observed through enzyme assays. The results of SEM microscopy revealed that the effect of the crude enzymes of EAWP-treated muskmelon caused morphological changes in F. incarnatum mycelia. Furthermore, treatment with EAWPs preserved postharvest quality in muskmelon, including with regard to texture stiffness and total chlorophyll contents, compared to untreated muskmelon. These results demonstrate that the pretreatment of muskmelon with EAWPs suppresses the development of F. incarnatum in the early stage of infection by regulating gene expression of CWDEs and elevating the activities of CWDEs, while also maintaining postharvest muskmelon quality.

Anthocyanins and reactive oxygen species: a team of rivals regulating plant development?

Anthocyanins are a family of water-soluble vacuolar pigments present in almost all flowering plants. The chemistry, biosynthesis and functions of these flavonoids have been intensively studied, in part due to their benefit for human health. Given that they are efficient antioxidants, intense research has been devoted to studying their possible roles against damage caused by reactive oxygen species (ROS). However, the redox homeostasis established between antioxidants and ROS is important for plant growth and development. On the one hand, high levels of ROS can damage DNA, proteins, and lipids, on the other, they are also required for cell signaling, plant development and stress responses. Thus, a balance is needed in which antioxidants can remove excessive ROS, while not precluding ROS from triggering important cellular signaling cascades. In this article, we discuss how anthocyanins and ROS interact and how a deeper understanding of the balance between them could help improve plant productivity, nutritional value, and resistance to stress, while simultaneously maintaining proper cellular function and plant growth.

Quenching effect of cerium oxide nanoparticles on singlet oxygen: validation of the potential for reaction with multiple reactive oxygen species

Here we studied cerium oxide nanoparticles (nanoceria) as an agent for the future treatment of oxidative damage by validating and evaluating its scavenging activity towards reactive oxygen species (ROS) in vitro. Nanoceria has been shown to mimic the activities of superoxide dismutase and catalase, degrading superoxide (O2•-) and hydrogen peroxide (H2O2). We examined the antioxidative activity of nanoceria, focusing on its ability to quench singlet oxygen (1O2) in an aqueous solution. Electron paramagnetic resonance (EPR) was used to determine the rates of second-order reactions between nanoceria and three ROS (1O2, O2•-, and H2O2) in aqueous solution, and its antioxidative abilities were demonstrated. Nanoceria shows a wide range of ultraviolet-light absorption bands and thus 1O2 was produced directly in a nanoceria suspension using high-frequency ultrasound. The quenching or scavenging abilities of nanoceria for 1O2 and hypoxanthine-xanthine oxidase reaction-derived O2•- were examined by EPR spin-trapping methods, and the consumption of H2O2 was estimated by the EPR oximetry method. Our results indicated that nanoceria interact not only with two previously reported ROS but also with 1O2. Nanoceria were shown to degrade O2•- and H2O2, and their ability to quench 1O2 may be one mechanism by which they protect against oxidative damage such as inflammation.