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Every year, unfavorable environmental factors significantly affect crop productivity and threaten food security. Plants are sessile; they cannot move to escape unfavorable environmental conditions, and therefore, they activate a variety of defense pathways. Among them are processes regulated by stress‐associated proteins (SAPs). SAPs have a specific zinc finger domain (A20) at the N‐terminus and either AN1 or C2H2 at the C‐terminus. SAP proteins are involved in many biological processes and in response to various abiotic or biotic constraints. Most SAPs play a role in conferring transgenic stress resistance and are stress‐inducible. The emerging field of SAPs in abiotic or biotic stress response regulation has attracted the attention of researchers. Although SAPs interact with various proteins to perform their functions, the exact mechanisms of these interactions remain incompletely understood. This review aims to provide a comprehensive understanding of SAPs, covering their diversity, structure, expression, and subcellular localization. SAPs play a pivotal role in enabling crosstalk between abiotic and biotic stress signaling pathways, making them essential for developing stress‐tolerant crops without yield penalties. Collectively, understanding the complex regulation of SAPs in stress responses can contribute to enhancing tolerance against various environmental stresses through several techniques such as transgenesis, classical breeding, or gene editing. [ABSTRACT FROM AUTHOR]

During land plant evolution, the number of genes encoding for components of the thiol redox regulatory network and the generator systems of reactive oxygen species (ROS) expanded, tentatively indicating that they have a role in tailored environmental acclimatization. This hypothesis has been validated both experimentally and theoretically during the last few decades. Recent developments of dynamic redox-sensitive GFP (roGFP)-based in vivo sensors for H2O2 and the redox potential of the glutathione pool have paved the way for dissecting the kinetics changes that occur in these crucial parameters in response to environmental stressors. The versatile cellular redox sensory and response regulatory system monitors alterations in redox metabolism and controls the activity of redox target proteins, and thereby affects most, if not all, cellular processes ranging from transcription to translation and metabolism. This review uses examples to describe the role of the redox- and ROS-dependent regulatory network in realising the appropriate responses to diverse environmental stresses. The selected case studies concern different environmental challenges, namely excess excitation energy, the heavy metal cadmium and the metalloid arsenic, nitrogen or phosphate shortages as examples for nutrient deficiency, wounding, and nematode infestation. Each challenge affects the redox-regulatory and ROS network, but our present state of knowledge also points toward pressing questions that remain open in relation to the translation of redox regulation to environmental acclimatization. [ABSTRACT FROM AUTHOR]

Photosynthesis is the foundation of life on Earth. However, if not well regulated, it can also generate excessive reactive oxygen species (ROS), which can cause photodamage. Regulation of photosynthesis is highly dynamic, responding to both environmental and metabolic cues, and occurs at many levels, from light capture to energy storage and metabolic processes. One general mechanism of regulation involves the reversible oxidation and reduction of protein thiol groups, which can affect the activity of enzymes and the stability of proteins. Such redox regulation has been well studied in stromal enzymes, but more recently, evidence has emerged of redox control of thylakoid lumenal enzymes. This review/hypothesis paper summarizes the latest research and discusses several open questions and challenges to achieving effective redox control in the lumen, focusing on the distinct environments and regulatory components of the thylakoid lumen, including the need to transport electrons across the thylakoid membrane, the effects of pH changes by the proton motive force (pmf) in the stromal and lumenal compartments, and the observed differences in redox states. These constraints suggest that activated oxygen species are likely to be major regulatory contributors to lumenal thiol redox regulation, with key components and processes yet to be discovered. [ABSTRACT FROM AUTHOR]

Cysteine thiols are susceptible to various oxidative posttranslational modifications (PTMs) due to their high chemical reactivity. Thiol‐based PTMs play a crucial role in regulating protein functions and are key contributors to cellular redox signaling. Although reversible thiol‐based PTMs, such as disulfide bond formation, S‐nitrosylation, and S‐glutathionylation, have been extensively studied for their roles in redox regulation, thiol sulfinic acid (–SO2H) modification is often perceived as irreversible and of marginal significance in redox signaling. Here, we revisit this narrow perspective and shed light on the redox regulatory roles of –SO2H in plant stress signaling. We provide an overview of protein sulfinylation in plants, delving into the roles of hydrogen peroxide‐mediated and plant cysteine oxidase‐catalyzed formation of –SO2H, highlighting the involvement of –SO2H in specific regulatory signaling pathways. Additionally, we compile the existing knowledge of the –SO2H reducing enzyme, sulfiredoxin, offering insights into its molecular mechanisms and biological relevance. We further summarize current proteomic techniques for detecting –SO2H and furnish a list of experimentally validated cysteine –SO2H sites across various species, discussing their functional consequences. This review aims to spark new insights and discussions that lead to further investigations into the functional significance of protein –SO2H‐based redox signaling in plants. Summary statement: This review expands upon the conventional understanding of cysteine thiol sulfinic acid modification and provides an updated overview of its redox‐dependent regulatory functions in the context of plant stress signaling pathways. [ABSTRACT FROM AUTHOR]

Thioredoxins (TRXs) are central to redox regulation, modulating enzyme activities to adapt metabolism to environmental changes. Previous research emphasized mitochondrial and microsomal TRX o1 and h2 influence on mitochondrial metabolism, including photorespiration and the tricarboxylic acid (TCA) cycle. Our study aimed to compare TRX‐based regulation circuits towards environmental cues mainly affecting photorespiration. Metabolite snapshots, phenotypes and CO2 assimilation were compared among single and multiple TRX mutants in the wild‐type and the glycine decarboxylase T‐protein knockdown (gldt1) background. Our analyses provided evidence for additive negative effects of combined TRX o1 and h2 deficiency on growth and photosynthesis. Especially metabolite accumulation patterns suggest a shared regulation mechanism mainly on mitochondrial dihydrolipoamide dehydrogenase (mtLPD1)‐dependent pathways. Quantification of pyridine nucleotides, in conjunction with 13C‐labelling approaches, and biochemical analysis of recombinant mtLPD1 supported this. It also revealed mtLPD1 inhibition by NADH, pointing at an additional measure to fine‐tune it's activity. Collectively, we propose that lack of TRX o1 and h2 perturbs the mitochondrial redox state, which impacts on other pathways through shifts in the NADH/NAD+ ratio via mtLPD1. This regulation module might represent a node for simultaneous adjustments of photorespiration, the TCA cycle and branched chain amino acid degradation under fluctuating environmental conditions. Summary statement: Thioredoxins o1 and h2 concertedly adapt the performance of mtLPD1‐dependent pathways towards short‐ and long‐term environmental changes. Simultaneous adjustments of mitochondrial pathway fluxes are achieved through fine tuning of mtLPD1 activity via redox regulation and subcellular NADH/NAD+ ratios. [ABSTRACT FROM AUTHOR]

Plants are sessile organisms that are often subjected to a multitude of environmental stresses, with the occurrence of these events being further intensified by global climate change. Crop species therefore require specific adaptations to tolerate climatic variability for sustainable food production. Plant stress results in excess accumulation of reactive oxygen species leading to oxidative stress and loss of cellular redox balance in the plant cells. Moreover, enhancement of cellular oxidation as well as oxidative signals has been recently recognized as crucial players in plant growth regulation under stress conditions. Multiple roles of redox regulation in crop production have been well documented, and major emphasis has focused on key redox-regulated proteins and non-protein molecules, such as NAD(P)H, glutathione, peroxiredoxins, glutaredoxins, ascorbate, thioredoxins and reduced ferredoxin. These have been widely implicated in the regulation of (epi)genetic factors modulating growth and health of crop plants, with an agricultural context. In this regard, priming with the employment of chemical and biological agents has emerged as a fascinating approach to improve plant tolerance against various abiotic and biotic stressors. Priming in plants is a physiological process, where prior exposure to specific stressors induces a state of heightened alertness, enabling a more rapid and effective defense response upon subsequent encounters with similar challenges. Priming is reported to play a crucial role in the modulation of cellular redox homeostasis, maximizing crop productivity under stress conditions and thus achieving yield security. By taking this into consideration, the present review is an up-to-date critical evaluation of promising plant priming technologies and their role in the regulation of redox components toward enhanced plant adaptations to extreme unfavorable environmental conditions. The challenges and opportunities of plant priming are discussed, with an aim of encouraging future research in this field toward effective application of priming in stress management in crops including horticultural species. [ABSTRACT FROM AUTHOR]

Formidable and often seemingly insurmountable conceptual, technical, and methodological challenges hamper the measurement of oxidative stress in humans. For instance, fraught and flawed methods, such as the thiobarbituric acid reactive substances assay kits for lipid peroxidation, rate-limit progress. To advance translational redox research, we present ten comprehensive "cheat codes" for measuring oxidative stress in humans. The cheat codes include analytical approaches to assess reactive oxygen species, antioxidants, oxidative damage, and redox regulation. They provide essential conceptual, technical, and methodological information inclusive of curated "do" and "don't" guidelines. Given the biochemical complexity of oxidative stress, we present a research question-grounded decision tree guide for selecting the most appropriate cheat code(s) to implement in a prospective human experiment. Worked examples demonstrate the benefits of the decision tree-based cheat code selection tool. The ten cheat codes define an invaluable resource for measuring oxidative stress in humans. [ABSTRACT FROM AUTHOR]

Disrupted in Schizophrenia 1 (DISC1) is a scaffold protein implicated in major mental illnesses including schizophrenia, with a significant negative impact on social life. To investigate if DISC1 affects social interactions in Drosophila melanogaster, we created transgenic flies with second or third chromosome insertions of the human full-length DISC1 (hflDISC1) gene fused to a UAS promotor (UAS-hflDISC1). Initial characterization of the insertion lines showed unexpected endogenous expression of the DISC1 protein that led to various behavioral and neurochemical phenotypes. Social interaction network (SIN) analysis showed altered social dynamics and organizational structures. This was in agreement with the altered levels of the locomotor activity of individual flies monitored for 24 h. Together with a decreased ability to climb vertical surfaces, the observed phenotypes indicate altered motor functions that could be due to a change in the function of the motor neurons and/or central brain. The changes in social behavior and motor function suggest that the inserted hflDISC1 gene influences nervous system functioning that parallels symptoms of DISC1-related mental diseases in humans. Furthermore, neurochemical analyses of transgenic lines revealed increased levels of hydrogen peroxide and decreased levels of glutathione, indicating an impact of DISC1 on the dynamics of redox regulation, similar to that reported in transgenic mammals. Future studies are needed to address the localization of DISC1 expression and to address how the redox parameter changes correlate with the observed behavioral changes.

Abstract SbtB is a PII-like protein that regulates the carbon-concentrating mechanism (CCM) in cyanobacteria. SbtB proteins can bind many adenyl nucleotides and possess a characteristic C-terminal redox sensitive loop (R-loop) that forms a disulfide bridge in response to the diurnal state of the cell. SbtBs also possess an ATPase/ADPase activity that is modulated by the redox-state of the R-loop. To investigate the R-loop in the cyanobacterium Synechocystis sp. PCC 6803, site-specific mutants, unable to form the hairpin and permanently in the reduced state, and a R-loop truncation mutant, were characterized under different inorganic carbon (Ci) and light regimes. Growth under diurnal rhythm showed a role of the R-loop as sensor for acclimation to changing light conditions. The redox-state of the R-loop was found to impact the binding of the adenyl-nucleotides to SbtB, its membrane association and thereby the CCM regulation, while these phenotypes disappeared after truncation of the R-loop. Collectively, our data imply that the redox-sensitive R-loop provides an additional regulatory layer to SbtB, linking the CO2-related signaling activity of SbtB with the redox state of cells, mainly reporting the actual light conditions. This regulation not only coordinates CCM activity in the diurnal rhythm but also affects the primary carbon metabolism.

Reactive oxygen species (ROS) play a crucial role in orchestrating a myriad of physiological processes within living systems. With the advent of materdicine, an array of nanomaterials has been intricately engineered to influence the redox equilibrium in biological milieus, thereby pioneering a distinctive therapeutic paradigm predicated on ROS‐centric biochemistry. Among these, two‐dimensional carbides, nitrides, and carbonitrides, collectively known as MXenes, stand out due to their multi‐valent and multi‐elemental compositions, large surface area, high conductivity, and pronounced local surface plasmon resonance effects, positioning them as prominent contributors in ROS modulation. This review aims to provide an overview of the advancements in harnessing MXenes for catalytic redox reactions in various biological applications, including tumor, anti‐infective, and anti‐inflammatory therapies. The emphasis lies on elucidating the therapeutic mechanism of MXenes, involving both pro‐oxidation and anti‐oxidation processes, underscoring the redox‐related therapeutic applications facilitated by self‐catalysis, photo‐excitation, and sono‐excitation properties of MXenes. Furthermore, this review highlights the existing challenges and outlines future development trends in leveraging MXenes for ROS‐involving disease treatments, marking a significant step towards the integration of these nanomaterials into clinical practice. [ABSTRACT FROM AUTHOR]

Reactive oxygen species and auxin play important roles in plant growth and development, and their signal transduction and regulatory mechanisms have always been an important field of plant science research. The classic pathway TIR1/AFB-Aux/IAA-ARF mediates nucleic auxin signaling through transcriptional regulation. However, how auxin signal is relayed from cytoplasm to nucleus is still unclear. Recently, Prof Li Chao's team from East China Normal University discovered that redox signals are involved in the auxin-regulated root hairing process. The auxin receptor protein TIR1/AFB2 undergoes Oxi-PTMs before migrating to the nucleus, which determines the initiation of the auxin transcriptional signal for root hair development, and this step is controlled by the upstream FER/LG1-RAC/ROP-RBOHC module. The results of this research have discovered the crosstalk mechanism between auxin and redox signals, and provide a paradigm for regulating biological processes through protein Oxi-PTMs. [ABSTRACT FROM AUTHOR]

Glutathione S-transferase omega 1 (GstO1) catalyzes deglutathionylation and plays an important role in the protein glutathionylation cycle in cells. GstO1 contains four conserved cysteine residues (C32, C90, C191, C236) found to be mutated in patients with associated diseases. In this study, we investigated the effects of cysteine mutations on the structure and function of GstO1 under different redox conditions. Wild-type GstO1 (WT) was highly sensitive to hydrogen peroxide (H2O2), which caused precipitation and denaturation at a physiological temperature. However, glutathione efficiently inhibited the H2O2-induced denaturation of GstO1. Cysteine mutants C32A and C236A exhibited redox-dependent stabilities and enzyme activities significantly different from those of WT. These results indicate that C32 and C236 play critical roles in GstO1 regulation by sensing redox environments and explain the pathological effect of cysteine mutations found in patients with associated diseases. [ABSTRACT FROM AUTHOR]

Plants accumulate high concentrations of ascorbate, commonly in their leaves, as a redox buffer. While ascorbate levels have increased during plant evolution, the mechanisms behind this phenomenon are unclear. Moreover, has the increase in ascorbate concentration been achieved without imposing any detrimental effects on the plants? In this review, we focus on potential transitions in two regulatory mechanisms related to ascorbate biosynthesis and the availability of cellular dehydroascorbate (DHA) during plant evolution. The first transition might be that the trigger for the transcriptional induction of VTC2 , which encodes the rate-limiting enzyme in ascorbate biosynthesis, has shifted from oxidative stress (in green algae) to light/photosynthesis (in land plants), probably enabling the continuous accumulation of ascorbate under illumination. This could serve as a preventive system against the unpredictable occurrence of oxidative stress. The second transition might be that DHA-degrading enzymes, which protect cells from the highly reactive DHA in green algae and mosses, have been lost in ferns or flowering plants. Instead, flowering plants may have increased glutathione concentrations to reinforce the DHA reduction capacity, possibly allowing ascorbate accumulation and avoiding the toxicity of DHA. These potential transitions may have contributed to strategies for plants' safe and effective accumulation of ascorbate. [ABSTRACT FROM AUTHOR]

Thioredoxin (Trx) is a small redox mediator protein involved in the regulation of various chloroplast functions by modulating the redox state of Trx target proteins in ever-changing light environments. Using reducing equivalents produced by the photosynthetic electron transport chain, Trx reduces the disulfide bonds on target proteins and generally turns on their activities. While the details of the protein-reduction mechanism by Trx have been well investigated, the oxidation mechanism that counteracts it has long been unclear. We have recently demonstrated that Trx-like proteins such as Trx-like2 and atypical Cys His-rich Trx (ACHT) can function as protein oxidation factors in chloroplasts. Our latest study on transgenic Arabidopsis plants indicated that the ACHT isoform ACHT2 is involved in regulating the thermal dissipation of light energy. To understand the role of ACHT2 in vivo, we characterized phenotypic changes specifically caused by ACHT2 overexpression in Arabidopsis. ACHT2-overexpressing plants showed growth defects, especially under high light conditions. This growth phenotype was accompanied with the impaired reductive activation of Calvin–Benson cycle enzymes, enhanced thermal dissipation of light energy, and decreased photosystem II activity. Overall, ACHT2 overexpression promoted protein oxidation that led to the inadequate activation of Calvin–Benson cycle enzymes in light and consequently induced negative feedback control of the photosynthetic electron transport chain. This study highlights the importance of the balance between protein reduction and oxidation in chloroplasts for optimal photosynthetic performance and plant growth. [ABSTRACT FROM AUTHOR]

In chronic inflammatory conditions and diseases accompanied by inflammation, the main indication range of systemically administered ozone, one basic mechanism of action has emerged following the low-dose ozone concept: Interference in the diverse biological redox equilibria, and its regulation at low concentrations. the very special role of the glutathione balance and its recovery. It starts with the oxidation of GSH (active form of glutathione) by "ozone peroxides", and after a considerable number of regulatory processes and mechanisms, finally leads to the regulation of the glutathione balance GSH ⇋ GSSG itself, the most important intracellular antioxidant system. Typically, the upregulation of GSH is demonstrated here in aging processes, in rheumatoid arthritis, the protection of liver intoxication and in post COVID patients. From this perspective, the redox bioregulator ozone and its fundamental reactions are reconsidered in this article. [ABSTRACT FROM AUTHOR]

Various chloroplast proteins are activated/deactivated during the light/dark cycle via the redox regulation system. Although the photosynthetic electron transport chain provides reducing power to redox-sensitive proteins via the ferredoxin (Fd)/thioredoxin (Trx) pathway for their enzymatic activity control, how the redox states of individual proteins are linked to electron transport efficiency remains uncharacterized. Here we addressed this subject with a focus on the photosynthetic induction phase. We used Arabidopsis plants, in which the amount of Fd–Trx reductase (FTR), a core component in the Fd/Trx pathway, was genetically altered. Several chloroplast proteins showed different redox shift responses toward low- and high-light treatments. The light-dependent reduction of Calvin–Benson cycle enzymes fructose 1,6-bisphosphatase (FBPase) and sedoheptulose 1,7-bisphosphatase (SBPase) was partially impaired in the FTR-knockdown ftrb mutant. Simultaneous analyses of chlorophyll fluorescence and P700 absorbance change indicated that the induction of the electron transport reactions was delayed in the ftrb mutant. FTR overexpression also mildly affected the reduction patterns of FBPase and SBPase under high-light conditions, which were accompanied by the modification of electron transport properties. Accordingly, the redox states of FBPase and SBPase were linearly correlated with electron transport rates. In contrast, ATP synthase was highly reduced even when electron transport reactions were not fully induced. Furthermore, the redox response of proton gradient regulation 5-like photosynthetic phenotype1 (PGRL1; a protein involved in cyclic electron transport) did not correlate with electron transport rates. Our results provide insights into the working dynamics of the redox regulation system and their differential associations with photosynthetic electron transport efficiency. [ABSTRACT FROM AUTHOR]

Fruit ripening is controlled by internal factors such as hormones and genetic regulators, as well as external environmental factors. However, the impact of redox regulation on fruit ripening remains elusive. Here, we explored the effects of L-cysteine hydrochloride (LCH), an antioxidant, on tomato fruit ripening and elucidated the underlying mechanism. The application of LCH effectively delayed tomato fruit ripening, leading to the suppression of carotenoid and lycopene biosynthesis and chlorophyll degradation, and a delayed respiration peak. Moreover, LCH-treated fruit exhibited reduced hydrogen peroxide (H2O2) accumulation and increased activities of superoxide dismutase (SOD), catalase (CAT), and monodehydroascorbate reductase (MDHAR), compared with control fruit. Furthermore, transcriptome analysis revealed that a substantial number of genes related to ethylene biosynthesis (ACS2, ACS4, ACO1, ACO3), carotenoid biosynthesis (PSY, PDS, ZDS, CRTISO), cell wall degradation (PG1/2, PL, TBG4, XTH4), and ripening-related regulators (RIN, NOR, AP2a, DML2) were downregulated by LCH, resulting in delayed ripening. These findings suggest that the application of LCH delays the ripening of harvested tomato fruit by modulating the redox balance and suppressing the expression of ripening-related genes. [ABSTRACT FROM AUTHOR]

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase (PRK) are two enzymes of the Calvin Benson cycle that stand out for some peculiar properties they have in common: (i) they both use the products of light reactions for catalysis (NADPH for GAPDH, ATP for PRK), (ii) they are both light-regulated through thioredoxins and (iii) they are both involved in the formation of regulatory supramolecular complexes in the dark or low photosynthetic conditions, with or without the regulatory protein CP12. In the complexes, enzymes are transiently inactivated but ready to recover full activity after complex dissociation. Fully active GAPDH and PRK are in large excess for the functioning of the Calvin-Benson cycle, but they can limit the cycle upon complex formation. Complex dissociation contributes to photosynthetic induction. CP12 also controls PRK concentration in model photosynthetic organisms like Arabidopsis thaliana and Chlamydomonas reinhardtii. The review combines in vivo and in vitro data into an integrated physiological view of the role of GAPDH and PRK dark complexes in the regulation of photosynthesis. • Calvin-Benson cycle regulation involves the formation of protein complexes in the dark or low light conditions. • GAPDH and PRK change their activity while changing their oligomerization state. • GAPDH and PRK activities are regulated at multiple levels in a light-dependent manner. • Thioredoxin redox state and metabolites coordinate the activation of PRK and GAPDH. • While activated GAPDH and PRK are in large excess for the Calvin-Benson cycle, complexed forms may limit RuBP regeneration. [ABSTRACT FROM AUTHOR]

Phosphatase and tensin homolog (PTEN) is a tumor suppressor due to its ability to regulate cell survival, growth, and proliferation by downregulating the PI3K/AKT signaling pathway. In addition, PTEN plays an essential role in other physiological events associated with cell growth demands, such as ischemia-reperfusion, nerve injury, and immune responsiveness. Therefore, recently, PTEN inhibition has emerged as a potential therapeutic intervention in these situations. Increasing evidence demonstrates that reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), are produced and required for the signaling in many important cellular processes under such physiological conditions. ROS have been shown to oxidize PTEN at the cysteine residue of its active site, consequently inhibiting its function. Herein, we provide an overview of studies that highlight the role of the oxidative inhibition of PTEN in physiological processes. [ABSTRACT FROM AUTHOR]

Summary: C4 plants typically operate a CO2 concentration mechanism from mesophyll (M) cells into bundle sheath (BS) cells. NADH dehydrogenase‐like (NDH) complex is enriched in the BS cells of many NADP‐malic enzyme (ME) type C4 plants and is more abundant in C4 than in C3 plants, but to what extent it is involved in the CO2 concentration mechanism remains to be experimentally investigated.We created maize and rice mutants deficient in NDH function and then used a combination of transcriptomic, proteomic, and metabolomic approaches for comparative analysis.Considerable decreases in growth, photosynthetic activities, and levels of key photosynthetic proteins were observed in maize but not rice mutants. However, transcript abundance for many cyclic electron transport (CET) and Calvin–Benson cycle components, as well as BS‐specific C4 enzymes, was increased in maize mutants. Metabolite analysis of the maize ndh mutants revealed an increased NADPH : NADP ratio, as well as malate, ribulose 1,5‐bisphosphate (RuBP), fructose 1,6‐bisphosphate (FBP), and photorespiration intermediates.We suggest that by optimizing NADPH and malate levels and adjusting NADP‐ME activity, NDH functions to balance metabolic and redox states in the BS cells of maize (in addition to ATP supply), coordinating photosynthetic transcript abundance and protein content, thus directly regulating the carbon flow in the two‐celled C4 system of maize. [ABSTRACT FROM AUTHOR]

Diabetes can disrupt physiological wound healing, caused by decreased levels or impaired activity of angiogenic factors. This can contribute to chronic inflammation, poor formation of new blood vessels, and delayed re-epithelialization. The present study describes the preclinical application of medical gas plasma to treat a dermal, full-thickness ear wound in streptozotocin (STZ)-induced diabetic mice. Gas plasma-mediated effects occurred in both sexes but with gender-specific differences. Hyperspectral imaging demonstrated gas plasma therapy changing microcirculatory parameters, particularly oxygen saturation levels during wound healing, presumably due to the gas plasma's tissue delivery of reactive species and other bioactive components. In addition, gas plasma treatment significantly affected cell adhesion by regulating focal adhesion kinase and vinculin, which is important in maintaining skin barrier function by regulating syndecan expression and increasing re-epithelialization. An anticipated stimulation of blood vessel formation was detected via transcriptional and translational increase of angiogenic factors in gas plasma-exposed wound tissue. Moreover, gas plasma treatment significantly affected inflammation by modulating systemic growth factors and cytokine levels. The presented findings may help explain the mode of action of successful clinical plasma therapy of wounds of diabetic patients. [ABSTRACT FROM AUTHOR]

A study of two enzymes in the brain reveals new insights into how redox reactions regulate the activity of protein kinases.

Autoimmune diseases, such as rheumatoid arthritis (RA) and systemic lupus erythematous, are regulated by polymorphisms in genes contributing to the NOX2 complex. Mutations in both Ncf1 and Ncf4 affect development of arthritis in experimental models of RA, but the different regulatory pathways mediated by NOX2-derived reactive oxygen species (ROS) have not yet been clarified.Here we address the possibility that intracellular ROS, regulated by the NCF4 protein (earlier often denoted p40phox) which interacts with endosomal membranes, could play an important role in the oxidation of cysteine peptides in mononuclear phagocytic cells, thereby regulating antigen presentation and activation of arthritogenic T cells.To study the role of NCF4 we used mice with an amino acid replacing mutation (NCF4R58A), which is known to affect interaction with endosomal membranes, leading to decreased intracellular ROS production. To study the impact of NCF4 on T cell activation, we used the glucose phosphate isomerase peptide GPI325-339, which contains two cysteine residues (325-339c-c). Macrophages from mice with the NCF458A mutation efficiently presented the peptide when the two cysteines were intact and not crosslinked, leading to a strong arthritogenic T cell response. T cell priming occurred in the draining lymph nodes (LNs) within 8 days after immunization. Clodronate treatment, which depletes antigen-presenting mononuclear phagocytes, ameliorated arthritis severity, whereas treatment with FYT720, which traps activated T cells in LNs, prohibited arthritis.We conclude that NCF4-dependent intracellular ROS maintains cysteine peptides in an oxidized crosslinked state, which prevents presentation of peptides recognized by non-tolerized T cells and thereby protects against autoimmune arthritis.

Type I cGMP-dependent protein kinases (PKGIs) are important components of various signaling pathways and are canonically activated by nitric oxide- and natriuretic peptide-induced cGMP generation. However, some reports have shown that PKGIα can also be activated in vitro by oxidizing agents. Using in vitro kinase assays, here, we found that purified PKGIα stored in PBS with Flag peptide became oxidized and activated even in the absence of oxidizing agent; furthermore, once established, this activation could not be reversed by reduction with DTT. We demonstrate that activation was enhanced by addition of Cu2+ before storage, indicating it was driven by oxidation and mediated by trace metals present during storage. Previous reports suggested that PKGIα Cys43, Cys118, and Cys196 play key roles in oxidation-induced kinase activation; we show that activation was reduced by C118A or C196V mutations, although C43S PKGIα activation was not reduced. In contrast, under the same conditions, purified PKGIβ activity only slightly increased with storage. Using PKGIα/PKGIβ chimeras, we found that residues throughout the PKGIα-specific autoinhibitory loop were responsible for this activation. To explore whether oxidants activate PKGIα in H9c2 and C2C12 cells, we monitored vasodilator-stimulated phosphoprotein phosphorylation downstream of PKGIα. While we observed PKGIα Cys43 crosslinking in response to H2O2 (indicating an oxidizing environment in the cells), we were unable to detect increased vasodilator-stimulated phosphoprotein phosphorylation under these conditions. Taken together, we conclude that while PKGIα can be readily activated by oxidation in vitro, there is currently no direct evidence of oxidation-induced PKGIα activation in vivo.

The cytosolic iron-sulfur (Fe-S) cluster assembly (CIA) pathway delivers Fe-S clusters to nuclear and cytosolic Fe-S proteins involved in essential cellular functions. Although the delivery process is regulated by the availability of iron and oxygen, it remains unclear how CIA components orchestrate the cluster transfer under varying cellular environments. Here, we utilized a targeted proteomics assay for monitoring CIA factors and substrates to characterize the CIA machinery. We find that nucleotide-binding protein 1 (NUBP1/NBP35), cytosolic iron-sulfur assembly component 3 (CIAO3/NARFL), and CIA substrates associate with nucleotide-binding protein 2 (NUBP2/CFD1), a component of the CIA scaffold complex. NUBP2 also weakly associates with the CIA targeting complex (MMS19, CIAO1, and CIAO2B) indicating the possible existence of a higher order complex. Interactions between CIAO3 and the CIA scaffold complex are strengthened upon iron supplementation or low oxygen tension, while iron chelation and reactive oxygen species weaken CIAO3 interactions with CIA components. We further demonstrate that CIAO3 mutants defective in Fe-S cluster binding fail to integrate into the higher order complexes. However, these mutants exhibit stronger associations with CIA substrates under conditions in which the association with the CIA targeting complex is reduced suggesting that CIAO3 and CIA substrates may associate in complexes independently of the CIA targeting complex. Together, our data suggest that CIA components potentially form a metabolon whose assembly is regulated by environmental cues and requires Fe-S cluster incorporation in CIAO3. These findings provide additional evidence that the CIA pathway adapts to changes in cellular environment through complex reorganization.

Reactive oxygen species (ROS) play a key role in a variety of biological processes, such as the perception of abiotic stress, the integration of different environmental signals, and the activation of stress response networks. Salt stress could induce an increased ROS accumulation in plants, disrupting intracellular redox homeostasis, leading to post-translational modifications (PTMs) of specific proteins, and eventually causing adaptive changes in metabolism. Here, we performed an iodoTMT-based proteomic approach to identify the sulfenylated proteins in B. napus root responsing to salt stress. Totally, 1 348 sulfenylated sites in 751 proteins were identified and these proteins were widely existed in different cell compartments and processes. Our study revealed that proteins with changed abundance and sulfenylation level in B. napus root under salt stress were mainly enriched in the biological processes of ion binding, glycolysis, ATP binding, and oxidative stress response. This study displays a landscape of sulfenylated proteins response to salt stress in B. napus root and provides some theoretical support for further understanding of the molecular mechanisms of redox regulation under salt stress in plants.

Formidable and often seemingly insurmountable conceptual, technical, and methodological challenges hamper the measurement of oxidative stress in humans. For instance, fraught and flawed methods, such as the thiobarbituric acid reactive substances assay kits for lipid peroxidation, rate-limit progress. To advance translational redox research, we present ten comprehensive “cheat codes” for measuring oxidative stress in humans. The cheat codes include analytical approaches to assess reactive oxygen species, antioxidants, oxidative damage, and redox regulation. They provide essential conceptual, technical, and methodological information inclusive of curated “do” and “don’t” guidelines. Given the biochemical complexity of oxidative stress, we present a research question-grounded decision tree guide for selecting the most appropriate cheat code(s) to implement in a prospective human experiment. Worked examples demonstrate the benefits of the decision tree-based cheat code selection tool. The ten cheat codes define an invaluable resource for measuring oxidative stress in humans.

Intracellular calcium signaling is involved in regulating the key functional mechanisms of the nervous system. The control of neuronal excitability and plasticity by calcium ions underlies the mechanisms of higher nervous activity, and the mechanisms of this control are of particular interest to researchers. A family of highly specialized neuronal proteins described in recent decades can translate the information contained in calcium signals into the regulation of channels, enzymes, receptors, and transcription factors. Neuronal calcium sensor-1 (NCS-1) is the most common member of the family, which is intensely expressed in central nervous system (CNS) cells; and controls several vital processes, such as neuronal growth and survival, reception, neurotransmission, and synaptic plasticity. In addition to calcium ions, NCS-1 can bind the so-called mobile, or signaling intracellular zinc, an increased concentration of which is a characteristic feature of cells in oxidative stress. Zinc coordination under these conditions stimulates NCS-1 oxidation to form a disulfide dimer (dNCS-1) with altered functional properties. A combined effect of mobile zinc and an increased redox potential of the medium can thus induce aberrant NCS-1 activity, including signals that promote survival of neuronal cells or induce their apoptosis and, consequently, the development of neurodegenerative processes. The review details the localization, expression regulation, structure, and molecular properties of NCS-1 and considers the current data on its signaling activity in health and disease, including zinc-dependent redox regulation cascades. [ABSTRACT FROM AUTHOR]

The present work compares the transcriptome data sets of post-imbibitional dehydration stress-raised seedlings of two contrasting indigenous aromatic rice cultivars (Oryza sativa L., Cultivars Jamainadu and Badshabhog) for unfolding genetic regulation of dehydration stress. The result of RNA-seq analysis in Illumina platform in general revealed significant cultivar-specific expression of genes under dehydration stress that substantiate the data of redox metabolic fingerprints (assessed in terms of differential efficacy of ascorbate–glutathione pathway, ROS–antioxidant interaction dynamics and sensitive biomarkers of oxidative stress). Both the cultivars showed a diverse global transcriptomic response under water-deficit condition. Transcripts selected for heatmap generation with proper annotation revealed genes that are significantly expressed and mainly involved in redox functions, signaling, membrane trafficking, replication, protein synthesis, etc. Gene ontology (GO) analysis proposed that dehydration stress in the drought-tolerant cultivar Badshabhog was attributable to the enhanced expression of genes associated with carbon dioxide-concentrating mechanism, peroxysomal biogenesis, protein modification, protein synthesis, mitochondrial electron transport chain functioning, intercellular protein transport, histone demethylation associated with developmental process, regulation of apoptosis, etc. The redox genes that got significantly over-expressed in the IARC Badshabhog vis-à-vis Jamainadu include l-ascorbate oxidase/peroxidase, monothiol glutaredoxin-S1, thioredoxin-like protein AAED1 (chloroplastic), thioredoxin-like protein CXXS1, NADH-dehydrogenase (ubiquinone)-1-beta subcomplex subunit 3-B, NADH-dehydrogenase subunit 6 and K, lipoxygenase 6 isoform-XI, etc. Overall, the results of the RNA-seq analysis led to the identification of cultivar-specific genes, with the cultivar Badshabhog exhibiting significantly greater molecular reprogramming for redox regulation and signaling necessary for combating dehydration stress. [ABSTRACT FROM AUTHOR]

Yield and aroma stability under drought in indigenous aromatic rice cultivars (IARCs), which needs significant attenuation of reduction of grain yield and quality through redox metabolic reprograming in contributory flag leaf was rarely studied and hence was the subject of present investigation. The redox landscaping of flag leaves of experimental IARCs done (Oryza sativa L., Cultivars Tulaipanji, Badshabhog, Jamainadu, and Sitabhog) during ensuing drought stress at grain-filling stage (65% of field capacity) and stress withdrawal (after 6 days) revealed tilt in the magnitude of redox homeostasis (assessed in terms of oxidation of DCFDA, accumulation of O2⋅−, H2O2, free radical scavenging property, non-protein thiol compounds, redox osmolytes, antioxidant pigments, and ROS-antioxidant interaction index), efficacy of RboH- ascorbate–glutathione/catalase pathway and sensitive biomarkers oxidative stress (accumulation of free carbonyl compounds, hydroperoxide, conjugated diene, and thiobarbituric acid reactive substances). The Cultivars capable of regulating ROS-antioxidant interaction dynamics at metabolic interface in flag leaf (Badshabhog and Tulaipanji) and able to prevent oxidative deterioration of flag leaf caused better restoration of aroma profile, 2-acetyl-1-pyrroline (2AP) content, agronomic characters, seed yield, and kernel quality than the others (Jamainadu and Sitabhog). Further, germplasm specific comparative assessment of metabolites shared by redox osmolyte proline and (2AP), exhibited metabolic cross talking toward regulation of dehydration induced oxidative stress and restoration of aroma production. Ability of maintenance of aromatic compounds, agronomic characters, seed yield, and kernel quality under drought stress through redox-regulatory acclimatory events of flag leaves in IARCs is suggested. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) sensing and signaling involves the reversible oxidation of particular thiols on particular proteins to modulate protein function in a dynamic manner. H2O2 can be generated from various intracellular sources, but their identities and relative contributions are often unknown. To identify endogenous "hotspots" of H2O2 generation on the scale of individual proteins and protein complexes, we generated a yeast library in which the H2O2 sensor HyPer7 was fused to the C-terminus of all protein-coding open reading frames (ORFs). We also generated a control library in which a redox-insensitive mutant of HyPer7 (SypHer7) was fused to all ORFs. Both libraries were screened side-by-side to identify proteins located within H2O2-generating environments. Screening under a variety of different metabolic conditions revealed dynamic changes in H2O2 availability highly specific to individual proteins and protein complexes. These findings suggest that intracellular H2O2 generation is much more localized and functionally differentiated than previously recognized. [ABSTRACT FROM AUTHOR]

SUMMARY: Diurnal dark to light transition causes profound physiological changes in plant metabolism. These changes require distinct modes of regulation as a unique feature of photosynthetic lifestyle. The activities of several key metabolic enzymes are regulated by light‐dependent post‐translational modifications (PTM) and have been studied at depth at the level of individual proteins. In contrast, a global picture of the light‐dependent PTMome dynamics is lacking, leaving the response of a large proportion of cellular function undefined. Here, we investigated the light‐dependent metabolome and proteome changes in Arabidopsis rosettes in a time resolved manner to dissect their kinetic interplay, focusing on phosphorylation, lysine acetylation, and cysteine‐based redox switches. Of over 24 000 PTM sites that were detected, more than 1700 were changed during the transition from dark to light. While the first changes, as measured 5 min after onset of illumination, occurred mainly in the chloroplasts, PTM changes at proteins in other compartments coincided with the full activation of the Calvin–Benson cycle and the synthesis of sugars at later timepoints. Our data reveal connections between metabolism and PTM‐based regulation throughout the cell. The comprehensive multiome profiling analysis provides unique insight into the extent by which photosynthesis reprograms global cell function and adds a powerful resource for the dissection of diverse cellular processes in the context of photosynthetic function. [ABSTRACT FROM AUTHOR]

The biomethane formation from 4 H2 + CO2 by pure cultures of two methanogens, Methanocaldococcus fervens and Methanobacterium thermophilum, has been studied. The goal of the study was to understand the regulation of the enzymatic steps associated with biomethane biosynthesis by H2, using metagenomic, pan-genomic, and transcriptomic approaches. Methanogenesis in the autotrophic methanogen M. fervens could be easily "switched off" and "switched on" by H2/CO2 within about an hour. In contrast, the heterotrophic methanogen M. thermophilum was practically insensitive to the addition of the H2/CO2 trigger although this methanogen also converted H2/CO2 to CH4. From practical points of view, the regulatory function of H2/CO2 suggests that in the power-to-gas (P2G) renewable excess electricity conversion and storage systems, the composition of the biomethane-generating methanogenic community is essential for sustainable operation. In addition to managing the specific hydrogenotrophic methanogenesis biochemistry, H2/CO2 affected several, apparently unrelated, metabolic pathways. The redox-regulated overall biochemistry and symbiotic relationships in the methanogenic communities should be explored in order to make the P2G technology more efficient. Key points : • Hydrogenotrophic methanogens may respond distinctly to H2/CO2 in bio-CH4 formation. • H2/CO2 can also activate metabolic routes, which are apparently unrelated to methanogenesis. • Sustainable conversion of the fluctuating renewable electricity to bio-CH4 is an option. [ABSTRACT FROM AUTHOR]

A functional product obtained from beet molasses vinasse (V) was supplemented to hypertensive rats (SHR) to assess its preventive effects against high blood pressure and endothelial dysfunction. Fifteen potential bioactive compounds (including phenolic acids, flavonoids and terpenoids, and glycosylated compounds) were identified and quantified in V by HPLC-MS. The most notable finding of the study was that the blood pressure values remained similar to those at the beginning of the study in the SHR+V group. At the same time, they increased progressively in the SHR control group, reaching a significant difference of 16% (p < 0.05) after 5 weeks of supplementation. Quantitative PCR and Western blot analyses of the aorta demonstrated that V ingestion by hypertensive rats led to decreased ACE mRNA levels and higher SOD2 and eNOS gene expression via promotion of Nrf2 transcriptional activity and down-regulation of the NF-κB pathway. These results are associated with an increased antioxidant, anti-inflammatory, and vasodilatory response. In conclusion, the intake of vinasse-derived products could mitigate hypertension and associated endothelial dysfunction. [ABSTRACT FROM AUTHOR]

Integration of reactive oxygen species (ROS)-mediated signal transduction pathways via redox sensors and the thiol-dependent signalling network is of increasing interest in cell biology for their implications in plant growth and productivity. Redox regulation is an important point of control in protein structure, interactions, cellular location, and function, with thioredoxins (TRXs) and glutaredoxins (GRXs) being key players in the maintenance of cellular redox homeostasis. The crosstalk between second messengers, ROS, thiol redox signalling, and redox homeostasis-related genes controls almost every aspect of plant development and stress response. We review the emerging roles of TRXs and GRXs in redox-regulated processes interacting with other cell signalling systems such as organellar retrograde communication and gene expression, especially in plants during their development and under stressful environments. This approach will cast light on the specific role of these proteins as redox signalling components, and their importance in different developmental processes during abiotic stress. [ABSTRACT FROM AUTHOR]

Yeast is a facultative anaerobe and uses diverse electron acceptors to maintain redox-regulated import of cysteine-rich precursors via the mitochondrial intermembrane space assembly (MIA) pathway. With the growing diversity of substrates utilizing the MIA pathway, understanding the capacity of the intermembrane space (IMS) to handle different types of stress is crucial. We used MS to identify additional proteins that interacted with the sulfhydryl oxidase Erv1 of the MIA pathway. Altered inheritance of mitochondria 32 (Aim32), a thioredoxin-like [2Fe-2S] ferredoxin protein, was identified as an Erv1-binding protein. Detailed localization studies showed that Aim32 resided in both the mitochondrial matrix and IMS. Aim32 interacted with additional proteins including redox protein Osm1 and protein import components Tim17, Tim23, and Tim22. Deletion of Aim32 or mutation of conserved cysteine residues that coordinate the Fe-S center in Aim32 resulted in an increased accumulation of proteins with aberrant disulfide linkages. In addition, the steady-state level of assembled TIM22, TIM23, and Oxa1 protein import complexes was decreased. Aim32 also bound to several mitochondrial proteins under nonreducing conditions, suggesting a function in maintaining the redox status of proteins by potentially targeting cysteine residues that may be sensitive to oxidation. Finally, Aim32 was essential for growth in conditions of stress such as elevated temperature and hydroxyurea, and under anaerobic conditions. These studies suggest that the Fe-S protein Aim32 has a potential role in general redox homeostasis in the matrix and IMS. Thus, Aim32 may be poised as a sensor or regulator in quality control for a broad range of mitochondrial proteins.

Glutathione S-transferase omega 1 (GstO1) catalyzes deglutathionylation and plays an important role in the protein glutathionylation cycle in cells. GstO1 contains four conserved cysteine residues (C32, C90, C191, C236) found to be mutated in patients with associated diseases. In this study, we investigated the effects of cysteine mutations on the structure and function of GstO1 under different redox conditions. Wild-type GstO1 (WT) was highly sensitive to hydrogen peroxide (H2O2), which caused precipitation and denaturation at a physiological temperature. However, glutathione efficiently inhibited the H2O2-induced denaturation of GstO1. Cysteine mutants C32A and C236A exhibited redox-dependent stabilities and enzyme activities significantly different from those of WT. These results indicate that C32 and C236 play critical roles in GstO1 regulation by sensing redox environments and explain the pathological effect of cysteine mutations found in patients with associated diseases.

BackgroundUveal melanoma (UVM) is a rare cancer that shows sex difference in incidence and survival, with little previous report for the underlying mechanism.MethodsThis study used the SEER data (1974-2016) for an age-dependent analysis on sex difference in UVM, and further used the TCGA-UVM genomics dataset for analyzing the differential gene expression profiles in tumors from men and women.ResultsOur results demonstrate a sex difference in older age (≥40 years) but not in younger patients, with men exhibiting a higher incidence rate than women. However, younger women have shown a continuous increasing trend since 1974. Examining the 11 major oncogenes and tumor suppressors in UVM revealed that EIF1AX showed a significant sex difference in mRNA accumulation and copy number variation, with female tumors expressing higher levels of EIF1AX and exhibiting more variations in copy numbers. EIF1AX mRNA levels were significantly inversely correlated with EIF1AX copy numbers in female tumors only, but not in male tumors. Differential gene expression analysis at the whole genomic level identified a set of 92 protein-coding and 16 RNA-coding genes which exhibited differential expression in men and women (fold of change cutoff at 1.7, adjusted p value < 0.05, FDR < 0.05). Network analysis showed significant difference in immune response and in disulfide bond formation, with EGR1/EGR2 and PDIA2 genes as regulators for immune response and disulfide bond formation, respectively. The melanocortin pathway which is linked to both melanin synthesis and obesity seems to be altered with unclear significance, as the sex difference in POMC, DCT/TYRP2, and MRAP2 was observed but with no clear direction.ConclusionThis study reveals possible mechanisms for the sex difference in tumorigenesis of UVM which has potentials for better understanding and prevention of UVM.

During our whole lifespan, from conception to death, the epigenomes of all tissues and cell types of our body integrate signals from the environment. This includes signals derived from our diet and the uptake of macro- and micronutrients. In most cases, this leads only to transient changes, but some effects of this epigenome programming process are persistent and can even be transferred to the next generation. Both epigenetic programming and redox processes are affected by the individual choice of diet and other lifestyle decisions like physical activity. The nutrient-gene communication pathways have adapted during human evolution and are essential for maintaining health. However, when they are maladaptive, such as in long-term obesity, they significantly contribute to diseases like type 2 diabetes and cancer. The field of nutrigenomics investigates nutrition-related signal transduction pathways and their effect on gene expression involving interactions both with the genome and the epigenomes. Several of these diet-(epi)genome interactions and the involved signal transduction cascades are redox-regulated. Examples include the effects of the NAD+/NADH ratio, vitamin C levels and secondary metabolites of dietary molecules from plants on the acetylation and methylation state of the epigenome as well as on gene expression through redox-sensitive pathways via the transcription factors NFE2L2 and FOXO. In this review, we summarize and extend on these topics as well as those discussed in the articles of this Special Issue and take them into the context of redox biology.

In this mini-review, we discuss the role of NF-κB, a proinflammatory transcription factor, in the expression of genes involved in inflammation, proliferation, and apoptosis pathways, and link it with prognosis of various human cancers, particularly non-small cell lung cancer (NSCLC). We and others have shown that NF-κB activity can be impacted by post-translational S-glutathionylation through reversible formation of a mixed disulfide bond between its cysteine residues and glutathione (GSH). Clinical data analysis showed that high expression of NF-κB correlated with shorter overall survival (OS) in NSCLC patients, suggesting a tumor promotion function for NF-κB. Moreover, NF-κB expression was associated with tumor stage, lymph node metastasis, and 5-year OS in these patients. NF-κB was over-expressed in the cytoplasm of tumor tissue compared to adjacent normal tissues. S-glutathionylation of NF-κB caused negative regulation by interfering with DNA binding activities of NF-κB subunits. In response to oxidants, S-glutathionylation of NF-κB also correlated with enhanced lung inflammation. Thus, S-glutathionylation is an important contributor to NF-κB regulation and clinical results highlight the importance of NF-κB in NSCLC, where NF-κB levels are associated with unfavorable prognosis.

Cancer is a dysregulated cellular level pathological condition that results in tumor formation followed by metastasis. In the heterogeneous tumor architecture, cancer stem cells (CSCs) are essential to push forward the progression of tumors due to their strong pro-tumor properties such as stemness, self-renewal, plasticity, metastasis, and being poorly responsive to radiotherapy and chemotherapeutic agents. Cancer stem cells have the ability to withstand various stress pressures by modulating transcriptional and translational mechanisms, and adaptable metabolic changes. Owing to CSCs heterogeneity and plasticity, these cells display varied metabolic and redox profiles across different types of cancers. It has been established that there is a disparity in the levels of Reactive Oxygen Species (ROS) generated in CSCs vs Non-CSC and these differential levels are detected across different tumors. CSCs have unique metabolic demands and are known to change plasticity during metastasis by passing through the interchangeable epithelial and mesenchymal-like phenotypes. During the metastatic process, tumor cells undergo epithelial to mesenchymal transition (EMT) thus attaining invasive properties while leaving the primary tumor site, similarly during the course of circulation and extravasation at a distant organ, these cells regain their epithelial characteristics through Mesenchymal to Epithelial Transition (MET) to initiate micrometastasis. It has been evidenced that levels of Reactive Oxygen Species (ROS) and associated metabolic activities vary between the epithelial and mesenchymal states of CSCs. Similarly, the levels of oxidative and metabolic states were observed to get altered in CSCs post-drug treatments. As oxidative and metabolic changes guide the onset of autophagy in cells, its role in self-renewal, quiescence, proliferation and response to drug treatment is well established. This review will highlight the molecular mechanisms useful for expanding therapeutic strategies based on modulating redox regulation and autophagy activation to targets. Specifically, we will account for the mounting data that focus on the role of ROS generated by different metabolic pathways and autophagy regulation in eradicating stem-like cells hereafter referred to as cancer stem cells (CSCs). [ABSTRACT FROM AUTHOR]

The protozoan parasite Plasmodium falciparum is the causative pathogen of the most severe form of malaria, for which novel strategies for treatment are urgently required. The primary energy supply for intraerythrocytic stages of Plasmodium is the production of ATP via glycolysis. Due to the parasite's strong dependence on this pathway and the significant structural differences of its glycolytic enzymes compared to its human counterpart, glycolysis is considered a potential drug target. In this study, we provide the first three-dimensional protein structure of P. falciparum hexokinase (PfHK) containing novel information about the mechanisms of PfHK. We identified for the first time a Plasmodium-specific insertion that lines the active site. Moreover, we propose that this insertion plays a role in ATP binding. Residues of the insertion further seem to affect the tetrameric interface and therefore suggest a special way of communication among the different monomers. In addition, we confirmed that PfHK is targeted and affected by oxidative posttranslational modifications (oxPTMs). Both S-glutathionylation and S-nitrosation revealed an inhibitory effect on the enzymatic activity of PfHK. [ABSTRACT FROM AUTHOR]

The antibody-linked oxi-state assay (ALISA) for quantifying target-specific cysteine oxidation can benefit specialist and non-specialist users. Specialists can benefit from time-efficient analysis and high-throughput target and/or sample n-plex capacities. The simple and accessible "off-the-shelf" nature of ALISA brings the benefits of oxidative damage assays to non-specialists studying redox-regulation. Until performance benchmarking establishes confidence in the "unseen" microplate results, ALISA is unlikely to be widely adopted. Here, we implemented pre-set pass/fail criteria to benchmark ALISA by robustly evaluating immunoassay performance in diverse biological contexts. ELISA-mode ALISA assays were accurate, reliable, and sensitive. For example, the average inter-assay CV for detecting 20%- and 40%-oxidised PRDX2 or GAPDH standards was 4.6% (range: 3.6–7.4%). ALISA displayed target-specificity. Immunodepleting the target decreased the signal by ∼75%. Single-antibody formatted ALISA failed to quantify the matrix-facing alpha subunit of the mitochondrial ATP synthase. However, RedoxiFluor quantified the alpha subunit displaying exceptional performance in the single-antibody format. ALISA discovered that (1) monocyte-to-macrophage differentiation amplified PRDX2-specific cysteine oxidation in THP-1 cells and (2) exercise increased GAPDH-specific cysteine oxidation in human erythrocytes. The "unseen" microplate data were "seen-to-be-believed" via orthogonal visually displayed immunoassays like the dimer method. Finally, we established target (n = 3) and sample (n = 100) n-plex capacities in ∼4 h with 50–70 min hands-on time. Our work showcases the potential of ALISA to advance our understanding of redox-regulation and oxidative stress. [Display omitted] • ALISA quantifies target-specific cysteine oxidation in a microplate. • ALISA is accurate, reliable, and sensitive. • ALISA generated new insights in diverse biological contexts. • The unseen microplate results were visually verified. • Specialists and non-specialists alike can benefit from ALISA. [ABSTRACT FROM AUTHOR]

Plants contain three NADPH‐thioredoxin reductases (NTR) located in the cytosol/mitochondria (NTRA/B) and the plastid (NTRC) with important metabolic functions. However, mutants deficient in all NTRs remained to be investigated. Here, we generated and characterised the triple Arabidopsis ntrabc mutant alongside with ntrc single and ntrab double mutants under different environmental conditions. Both ntrc and ntrabc mutants showed reduced growth and substantial metabolic alterations, especially in sink leaves and under high CO2 (HC), as compared to the wild type. However, ntrabc showed higher effective quantum yield of PSII under both constant and fluctuating light conditions, altered redox states of NADH/NAD+ and glutathione (GSH/GSSG) and lower potential quantum yield of PSII in sink leaves in ambient but not high CO2 concentrations, as compared to ntrc, suggesting a functional interaction between chloroplastic and extra‐chloroplastic NTRs in photosynthesis regulation depending on leaf development and environmental conditions. Our results unveil a previously unknown role of the NTR system in regulating sink leaf metabolism and plant acclimation to HC, while it is not affecting full plant development, indicating that the lack of the NTR system can be compensated, at least to some extent, by other redox mechanisms. Summary Statement: We unveil that NTRC is crucial for sink leaf metabolism and plant acclimation to high CO2. Although Arabidopsis plants lacking all NADPH‐thioredoxin reductases (NTRs) have severely reduced growth, they produced viable seeds, indicating that NTRs are not essential for plant development and compensated by other redox mechanisms. [ABSTRACT FROM AUTHOR]

This review provides an overview of molecular mechanisms of intracellular signal transduction involving free radicals. The structure and functions of enzymes that can produce superoxide anion-radical and hydrogen peroxide are considered in detail. The mechanisms of regulation of cell properties with the participation of specialized redox chains formed by a group of proteins interacting through electron transport processes are discussed. Genetically mediated mechanisms of regulation of cellular redox homeostasis are analyzed. Particular attention is paid to the issue concerning quantitative characterization of the network of interactions of oxidizing and reducing agents, which determines the species-specific and individual characteristics of redox homeostasis and the stress response of cells. [ABSTRACT FROM AUTHOR]

Plants contain three NADPH‐thioredoxin reductases (NTR) located in the cytosol/mitochondria (NTRA/B) and the plastid (NTRC) with important metabolic functions. However, mutants deficient in all NTRs remained to be investigated. Here, we generated and characterised the triple Arabidopsis ntrabc mutant alongside with ntrc single and ntrab double mutants under different environmental conditions. Both ntrc and ntrabc mutants showed reduced growth and substantial metabolic alterations, especially in sink leaves and under high CO2 (HC), as compared to the wild type. However, ntrabc showed higher effective quantum yield of PSII under both constant and fluctuating light conditions, altered redox states of NADH/NAD+ and glutathione (GSH/GSSG) and lower potential quantum yield of PSII in sink leaves in ambient but not high CO2 concentrations, as compared to ntrc, suggesting a functional interaction between chloroplastic and extra‐chloroplastic NTRs in photosynthesis regulation depending on leaf development and environmental conditions. Our results unveil a previously unknown role of the NTR system in regulating sink leaf metabolism and plant acclimation to HC, while it is not affecting full plant development, indicating that the lack of the NTR system can be compensated, at least to some extent, by other redox mechanisms. Summary Statement: We unveil that NTRC is crucial for sink leaf metabolism and plant acclimation to high CO2. Although Arabidopsis plants lacking all NADPH‐thioredoxin reductases (NTRs) have severely reduced growth, they produced viable seeds, indicating that NTRs are not essential for plant development and compensated by other redox mechanisms. [ABSTRACT FROM AUTHOR]

Autophagy is a catabolic pathway that functions as a degradative and recycling process to maintain cellular homeostasis in most eukaryotic cells, including photosynthetic organisms such as microalgae. This process involves the formation of double-membrane vesicles called autophagosomes, which engulf the material to be degraded and recycled in lytic compartments. Autophagy is mediated by a set of highly conserved autophagy-related (ATG) proteins that play a fundamental role in the formation of the autophagosome. The ATG8 ubiquitin-like system catalyzes the conjugation of ATG8 to the lipid phosphatidylethanolamine, an essential reaction in the autophagy process. Several studies identified the ATG8 system and other core ATG proteins in photosynthetic eukaryotes. However, how ATG8 lipidation is driven and regulated in these organisms is not fully understood yet. A detailed analysis of representative genomes from the entire microalgal lineage revealed a high conservation of ATG proteins in these organisms with the remarkable exception of red algae, which likely lost ATG genes before diversification. Here, we examine in silico the mechanisms and dynamic interactions between different components of the ATG8 lipidation system in plants and algae. Moreover, we also discuss the role of redox post-translational modifications in the regulation of ATG proteins and the activation of autophagy in these organisms by reactive oxygen species. [Display omitted] • The emergence of photosynthesis reshaped cellular metabolism but maintained major catabolic processes such as autophagy. • Autophagy plays an essential role to overcome nutrient starvation and oxidative stress in photosynthetic eukaryotes. • Thioester interactions are conserved in proteins from the ATG8 system among photosynthetic eukaryotes. • Mountain evidence indicates that ROS modulate autophagy although the underlying mechanisms remain largely unknown. [ABSTRACT FROM AUTHOR]

Thiol/disulfide-based redox regulation is a ubiquitous post-translational protein modification. In plant chloroplasts, this regulatory mechanism is tightly associated with the light-dependent activation of photosynthetic enzymes (e.g. Calvin–Benson cycle enzymes). A thioredoxin (Trx)-mediated pathway was discovered to transmit light signals as a reducing power about half a century ago; since then, it has been accepted as the basic machinery of chloroplast redox regulation. However, during the past two decades, it has been increasingly apparent that plants have acquired multiple Trx isoforms and Trx-like proteins in chloroplasts. Furthermore, proteomics-based analyses have identified various chloroplast enzymes as potential targets of redox regulation. These facts highlight the necessity to revisit the molecular basis and physiological importance of the redox regulation system in chloroplasts. Recent studies have revealed novel aspects of this system, including unprecedented redox-regulated processes in chloroplasts and the functional diversity of Trx family proteins. Of particular significance is the identification of protein-oxidizing pathways that turn off photosynthetic metabolism during light-to-dark transitions. In this review, we summarize current insights into the redox regulation network in chloroplasts. [ABSTRACT FROM AUTHOR]