Redox Targets Research Articles

Unresolved questions in the regulation of skeletal muscle insulin action by reactive oxygen species.

Reactive oxygen species (ROS) are well-established signaling molecules implicated in a wide range of cellular processes, including both oxidative stress and intracellular redox signaling. In the context of insulin action within its target tissues, ROS have been reported to exert both positive and negative regulatory effects. However, the precise molecular mechanisms underlying this duality remain unclear. This Review examines the complex role of ROS in insulin action, with a particular focus on skeletal muscle. We aim to address three critical aspects: (a) the proposed intracellular pro-oxidative redox shift elicited by insulin, (b) the evidence supporting that redox-sensitive cysteine modifications impact insulin signaling and action, and (c) cellular mechanisms underlying how ROS can paradoxically act as both enhancers and inhibitors of insulin action. This Review underscores the urgent need for more systematic research to identify specific reactive species, redox targets, and the physiological significance of redox signaling in maintaining insulin action and metabolic health, with a particular emphasis on human skeletal muscle.

Time-resolved HT-SAXS discovers allosteric chemotypes for redox target AIF.

Time-resolved HT-SAXS discovers allosteric chemotypes for redox target AIF.

The centrality of redox regulation and sensing of reactive oxygen species in abiotic and biotic stress acclimatization.

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.

Thioredoxin (Trx): A redox target and modulator of cellular senescence and aging-related diseases

Thioredoxin (Trx) is a compact redox-regulatory protein that modulates cellular redox state by reducing oxidized proteins. Trx exhibits dual functionality as an antioxidant and a cofactor for diverse enzymes and transcription factors, thereby exerting influence over their activity and function. Trx has emerged as a pivotal biomarker for various diseases, particularly those associated with oxidative stress, inflammation, and aging. Recent clinical investigations have underscored the significance of Trx in disease diagnosis, treatment, and mechanistic elucidation. Despite its paramount importance, the intricate interplay between Trx and cellular senescence—a condition characterized by irreversible growth arrest induced by multiple aging stimuli—remains inadequately understood. In this review, our objective is to present a comprehensive and up-to-date overview of the structure and function of Trx, its involvement in redox signaling pathways and cellular senescence, its association with aging and age-related diseases, as well as its potential as a therapeutic target. Our review aims to elucidate the novel and extensive role of Trx in senescence while highlighting its implications for aging and age-related diseases.

Redox pathways in melanoma.

Cases of melanoma are doubling every 12 years, and in stages III and IV, the disease is associated with high mortality rates concomitant with unresectable metastases and therapeutic drug resistance. Despite some advances in treatment success, there is a marked need to understand more about the pathology of the disease. The present review provides an overview of how melanoma cells use and modulate redox pathways to facilitate thiol homeostasis and melanin biosynthesis and describes plausible redox targets that may improve therapeutic approaches in managing malignant disease and metastasis. Melanotic melanoma has some unique characteristics. Making melanin requires a considerable dedication of cellular energy resources and utilizes glutathione and glutathione transferases in certain steps in the biosynthetic pathway. Melanin is an antioxidant but is also functionally important in hematopoiesis and influential in various aspects of host immune responses, giving it unique characteristics. Together with other redox traits that are specific to melanoma, a discussion of possible therapeutic approaches is also provided.

Redox-mediated activation of ATG3 promotes ATG8 lipidation and autophagy progression in Chlamydomonas reinhardtii.

Autophagy is one of the main degradative pathways used by eukaryotic organisms to eliminate useless or damaged intracellular material to maintain cellular homeostasis under stress conditions. Mounting evidence indicates a strong interplay between the generation of reactive oxygen species and the activation of autophagy. Although a tight redox regulation of autophagy has been shown in several organisms, including microalgae, the molecular mechanisms underlying this control remain poorly understood. In this study, we have performed an in-depth in vitro and in vivo redox characterization of ATG3, an E2-activating enzyme involved in ATG8 lipidation and autophagosome formation, from 2 evolutionary distant unicellular model organisms: the green microalga Chlamydomonas (Chlamydomonas reinhardtii) and the budding yeast Saccharomyces cerevisiae. Our results indicated that ATG3 activity from both organisms is subjected to redox regulation since these proteins require reducing equivalents to transfer ATG8 to the phospholipid phosphatidylethanolamine. We established the catalytic Cys of ATG3 as a redox target in algal and yeast proteins and showed that the oxidoreductase thioredoxin efficiently reduces ATG3. Moreover, in vivo studies revealed that the redox state of ATG3 from Chlamydomonas undergoes profound changes under autophagy-activating stress conditions, such as the absence of photoprotective carotenoids, the inhibition of fatty acid synthesis, or high light irradiance. Thus, our results indicate that the redox-mediated activation of ATG3 regulates ATG8 lipidation under oxidative stress conditions in this model microalga.

Redox Targets for Phosphine–Boranes

Understanding the complex mechanisms underlying redox-mediated biological processes is a fundamental pillar of cellular biology. We describe the identification and quantification of disulfide formation and reduction in response to phosphine–borane complexes. We illustrate the specific cysteine reduction effects of the novel phosphine–borane complex bis(3-propionic acid methyl ester) phenylphosphine–borane complex (PB1) on cultured 661W cells. A total of 1073 unique protein fragments from 628 unique proteins were identified and quantified, of which 13 were found to be statistically significant in comparison to control cells. Among the 13 identified proteins were Notch1, HDAC1, UBA1, USP7, and subunits L4 and L7 of the 60S ribosomal subunit, all of which are involved in redox or cell death-associated pathways. Leveraging the ability of tandem mass tagging mass spectrometry to provide quantitative data in an exploratory manner provides insight into the effect PB1 and other phosphine–borane compounds may have on the cysteine redoxome.

Organic Redox Targeting Flow Battery Utilizing a Hydrophilic Polymer and Its In-Operando Characterization via State-of-Charge Monitoring of The Redox Mediator.

The hydrophilic poly(2,2,6,6-tetramethylpiperdinyloxy-4-yl-methacrylamide) (PTMAm) was utilized as redox target material in an aqueous organic redox targeting flow battery (RTFB). This polymer is processed into granules, which contain a conductive agent and an alginate binder. By this, a hydrophilic, yet water-insoluble redox target can be obtained. The target was combined with the redox mediator molecule N,N,N-trimethyl-2-oxo-2-[(2,2,6,6-tetramethylpiperidin-4-yloxyl)amino]ethan-1-ammonium chloride (TEMPOAmide), that has been reported earlier as flow battery active material. This target/mediator combination has been characterized electrochemically and flow battery testing has been done. Furthermore, in-operando characterization of the redox target via electrolyte state-of-charge (SOC) monitoring has been performed for the first time. The approach provides estimates for the redox target's SOC changes during cycling. In addition, a figure of merit - the "redox targetivity" - is proposed, which provides insights into the efficiency of the targeting reaction and supports the future optimization of materials, cell designs, and operational parameters for RTFBs.

Role of Oxidative Stress in Ocular Diseases: A Balancing Act.

Redox homeostasis is a delicate balancing act of maintaining appropriate levels of antioxidant defense mechanisms and reactive oxidizing oxygen and nitrogen species. Any disruption of this balance leads to oxidative stress, which is a key pathogenic factor in several ocular diseases. In this review, we present the current evidence for oxidative stress and mitochondrial dysfunction in conditions affecting both the anterior segment (e.g., dry eye disease, keratoconus, cataract) and posterior segment (age-related macular degeneration, proliferative vitreoretinopathy, diabetic retinopathy, glaucoma) of the human eye. We posit that further development of therapeutic interventions to promote pro-regenerative responses and maintenance of the redox balance may delay or prevent the progression of these major ocular pathologies. Continued efforts in this field will not only yield a better understanding of the molecular mechanisms underlying the pathogenesis of ocular diseases but also enable the identification of novel druggable redox targets and antioxidant therapies.

Understanding molecular and electrochemical charge transfer: theory and computations.

Electron, proton, and proton-coupled electron transfer (PCET) are crucial elementary processes in chemistry, electrochemistry, and biology. We provide here a gentle overview of retrospective and currently developing theoretical formalisms of chemical, electrochemical and biological molecular charge transfer processes, with examples of how to bridge electron, proton, and PCET theory with experimental data. We offer first a theoretical minimum of molecular electron, proton, and PCET processes in homogeneous solution and at electrochemical interfaces. We illustrate next the use of the theory both for simple electron transfer processes, and for processes that involve molecular reorganization beyond the simplest harmonic approximation, with dissociative electron transfer and inclusion of all charge transfer parameters. A core example is the electrochemical reduction of the S2O82- anion. This is followed by discussion of core elements of proton and PCET processes and the electrochemical dihydrogen evolution reaction on different metal, semiconductor, and semimetal (say graphene) electrode surfaces. Other further focus is on stochastic chemical rate theory, and how this concept can rationalize highly non-traditional behaviour of charge transfer processes in mixed solvents. As a second major area we address ("long-range") chemical and electrochemical electron transfer through molecular frameworks using notions of superexchange and hopping. Single-molecule and single-entity electrochemistry are based on electrochemical scanning probe microscopies. (In operando) scanning tunnelling microscopy (STM) and atomic force microscopy (AFM) are particularly emphasized, with theoretical notions and new molecular electrochemical phenomena in the confined tunnelling gap. Single-molecule surface structure and electron transfer dynamics are illustrated by self-assembled thiol molecular monolayers and by more complex redox target molecules. This discussion also extends single-molecule electrochemistry to bioelectrochemistry of complex redox metalloproteins and metalloenzymes. Our third major area involves computational overviews of molecular and electronic structure of the electrochemical interface, with new computational challenges. These relate to solvent dynamics in bulk and confined space (say carbon nanostructures), electrocatalysis, metallic and semiconductor nanoparticles, d-band metals, carbon nanostructures, spin catalysis and "spintronics", and "hot" electrons. Further perspectives relate to metal-organic frameworks, chiral surfaces, and spintronics.

Nox4 promotes endothelial differentiation through chromatin remodeling

RationaleNox4 is a constitutively active NADPH oxidase that constantly produces low levels of H2O2. Thereby, Nox4 contributes to cell homeostasis and long-term processes, such as differentiation. The high expression of Nox4 seen in endothelial cells contrasts with the low abundance of Nox4 in stem cells, which are accordingly characterized by low levels of H2O2. We hypothesize that Nox4 is a major contributor to endothelial differentiation, is induced during the process of differentiation, and facilitates homeostasis of the resulting endothelial cells. ObjectiveTo determine the role of No×4 in differentiation of murine inducible pluripotent stem cells (miPSC) into endothelial cells (ECs). Methods and resultsmiPSC, generated from mouse embryonic wildtype (WT) and Nox4−/− fibroblasts, were differentiated into endothelial cells (miPSC-EC) by stimulation with BMP4 and VEGF. During this process, Nox4 expression increased and knockout of Nox4 prolonged the abundance of pluripotency markers, while expression of endothelial markers was delayed in differentiating Nox4-depleted iPSCs. Eventually, angiogenic capacity of iPSC-ECs is reduced in Nox4 deficient cells, indicating that an absence of Nox4 diminishes stability of the reached phenotype. As an underlying mechanism, we identified JmjD3 as a redox target of Nox4. iPSC-ECs lacking Nox4 display a lower nuclear abundance of the histone demethylase JmjD3, resulting in an increased triple methylation of histone 3 (H3K27me3), which serves as a repressive mark for several genes involved in differentiation. ConclusionsNox4 promotes differentiation of miPSCs into ECs by oxidation of JmjD3 and subsequent demethylation of H3K27me3, which forced endothelial differentiation and stability.

Magnetic mesoporous silica nanoparticles mediated redox and pH dual-responsive target drug delivery for combined magnetothermal therapy and chemotherapy

A combination of multiple therapies is conducive to the treatment efficacy of cancer. Chemotherapy combined with magnetothermal therapy provides an outstanding synergy for cancer treatment. In this study, magnetic mesoporous silica nanoparticles (MMSN) were developed as a multipurpose nanoplatform for doxorubicin (DOX) delivery and magnetothermal treatment of cancer simultaneously. The MMSN were composed of Fe3O4 and mesoporous silica as core and shell. The folic acid (FA) linked chitosan (CS) was conjugated at the outlets of MMSN (MMSN-SS-FA) using disulfide bonds to avert the premature release of the drug in mesopores of MMSN, target folate receptor-overexpressed cancer cells and increase the safety and physiological stability of MMSN. The temperature of the MMSN suspension could be elevated from 37 °C to 45 °C at the concentration of 1 mg/mL under an alternating magnetic field (AMF), which exceeded the tumor ablating temperature. The in vitro drug release proved that the DOX/MMSN-SS-FA displayed the redox/pH/AMF multiple-responsive release. The cellular uptake results indicated that the MMSN-SS-FA could target folate receptor-overexpressed HeLa cells. The DOX/MSNS-SS-FA with AMF had the highest cytotoxicity at the equivalent drug concentration towards HeLa cells with a combination index (CI) of 0.276, demonstrating the synergistic treatment effect of chemotherapy and magnetic-thermal therapy. Meanwhile, the DOX/MMSN-SS-FA+AMF showed the strongest tumor inhibitory effect of 84 % on tumor growth. Therefore, the constructed MMSN-SS-FA with good biocompatibility and biosafety can act as multifunctional nano-platforms for tumor treatment.

All-Organic Redox Targeting with a Single Redox Moiety: Combining Organic Radical Batteries and Organic Redox Flow Batteries.

The volumetric capacities and the lifetime of organic redox flow batteries (RFBs) are strongly dependent on the concentrations of the redox-active molecules in the electrolyte. Single-molecule redox targeting represents an efficient approach toward realizing viable organic RFBs with low to moderate electrolyte concentrations. For the first time, an all-organic Nernstian potential-driven redox targeting system is investigated that directly combines a single-electrode material from organic radical batteries (ORBs) with a single redox couple of an aqueous, organic RFB, which are based on the same redox moiety. Namely, poly(TEMPO-methacrylate) (PTMA) is utilized as the redox target ("solid booster") and N,N,N-2,2,6,6-heptamethylpiperidinyloxy-4-ammonium chloride (TMATEMPO) is applied as the sole redox mediator to demonstrate the redox targeting mechanisms between the storage materials of both battery types. The formal potentials of both molecules are investigated, and the targeting mechanism is verified by cyclic voltammetry and state-of-charge measurements. Finally, battery cycling experiments demonstrate that 78-90% of the theoretical capacity of the ORB electrode material can be addressed when this material is present as the redox target in the electrolyte tank of an operating, aqueous organic RFB.

A novel tin based hydroxamic acid complex induces apoptosis through redox imbalance and targets Stat3/JNK1/MMP axis to overcome drug resistance in cancer

Undesired toxicity and emergence of multidrug resistance (MDR) are the major impediments to the successful application of organotin-based compounds against cancer. Since oxalyl-bis(N-phenyl)hydroxamic acid (OBPHA) exerts significant efficacy against cancer, we believe that derivatives of OBPHA including organotin molecule can show a promising effect against cancer. Herein, we have selected three previously characterized OBPHA derivatives viz., succinyl-bis(N-phenyl)hydroxamic acid (SBPHA), diphenyl-tin succinyl-bis(N-phenyl)hydroxamic acid (Sn-SBPHA), malonyl-bis(N-phenyl)hydroxamic acid (MBPHA) and evaluated their antiproliferative efficacy against both drug-resistant (CEM/ADR5000; EAC/Dox) and sensitive (CCRF-CEM; HeLa; EAC/S) cancers. Data revealed that Sn-SBPHA selectively targets drug-resistant and sensitive cancers without inducing any significant toxicity to normal cells (Chang Liver). Moreover, shortening of the backbone of SBPHA enhances the efficacy of the newly formed molecule MBPHA by targeting only drug-sensitive cancers. Sn-SBPHA induces caspase3-dependent apoptosis through redox-imbalance in both drug-resistant and sensitive cancer. Sn-SBPHA also reduced the activation and expression of both MMP2 and MMP9 without altering the expression status of TIMP1 and TIMP2 in drug-resistant cancer. In addition, Sn-SBPHA reduced the activation of both STAT3 and JNK1, the transcriptional modulator of MMPs, in a redox-dependent manner in CEM/ADR5000 cells. Thus, Sn-SBPHA targets MMPs by modulating STAT3 and JNK1 in a redox-dependent manner. However, MBPHA and SBPHA fail to target drug resistance and both drug-resistant and sensitive cancer respectively. Furthermore, Sn-SBPHA significantly increases the lifespan of doxorubicin-resistant and sensitive Ehrlich Ascites Carcinoma-bearing mice without inducing any significant systemic toxicity. Therefore, Sn-SBPHA has the therapeutic potential to target and overcome MDR in cancer.

Cardiovascular Risk Stratification Based on Oxidative Stress for Early Detection of Pathology.

Aims: Current cardiovascular (CV) risk prediction algorithms are able to quantify the individual risk of CV disease. However, CV risk in young adults is underestimated due to the high dependency of age in biomarker-based algorithms. Because oxidative stress is associated with CV disease, we sought to examine CV risk stratification in young adults based on oxidative stress to approach the discovery of new markers for early detection of pathology. Results: Young adults were stratified into (i) healthy controls, (ii) subjects with CV risk factors, and (iii) patients with a reported CV event. Plasma samples were analyzed using FASILOX, a novel approach to interrogate the dynamic thiol redox proteome. We also analyzed irreversible oxidation by targeted searches using the Uniprot database. Irreversible oxidation of cysteine (Cys) residues was greater in patients with reported CV events than in healthy subjects. These results also indicate that oxidation is progressive. Moreover, we found that glutathione reductase and glutaredoxin 1 proteins are differentially expressed between groups and are proteins involved in antioxidant response, which is in line with the impaired redox homeostasis in CV disease. Innovation: This study, for the first time, describes the oxidative stress (reversible and irreversible Cys oxidation) implication in human plasma according to CV risk stratification. Conclusion: The identification of redox targets and the quantification of protein and oxidative changes might help to better understand the role of oxidative stress in CV disease, and aid stratification for CV events beyond traditional prognostic and diagnostic markers. Antioxid. Redox Signal. 35, 602-617.

STM studies of electron transfer through single molecules at electrode-electrolyte interfaces

Electrochemical scanning tunnelling microscopy (EC-STM) is one of the most important tools in modern interfacial electrochemistry. Over several decades it has proven its worth by providing in-situ atomic and molecular scale visualisations of electrode surfaces, but its value goes far beyond topographic imaging. This article discusses the use of EC-STM as a tool for quantitatively studying mechanisms of electron transfer (ET) at electrode-electrolyte interfaces. In combination with theoretical modelling, it has been revealing mechanistic details of charge transfer across molecules at electrochemical interfaces which are of broad interest to a wide range of electrochemists. This article discusses different ways in which the EC-STM can be deployed to monitor charge flow through single molecules and thereby analyse ET mechanisms. Mechanisms covered range from superexchange to 2-step hopping ones such as the Kuznetsov Ulstrup (KU) mechanism. Literature examples of a variety of redox and non-redox molecular targets are used to describe how measurements of single molecule conductance as a function of electrode potential can be used to analyse charge transfer through single molecules. The review finishes by highlighting some of the most recent work and new developments which will ensure that EC-STM will continue to be an important tool for studying ET mechanisms at electrode-electrolyte interfaces.

Novel and Converging Ways of NOX2 and SOD3 in Trafficking and Redox Signaling in Macrophages.

Macrophages and related tissue macrophage populations use the classical NADPH oxidase (NOX2) for the regulated production of superoxide and derived oxidants for pathogen combat and redox signaling. With an emphasis on macrophages, we discuss how sorting into secretory storage vesicles, agonist-responsive membrane trafficking, and segregation into sphingolipid and cholesterol-enriched microdomains (lipid rafts) determine the subcellular distribution and spatial organization of NOX2 and superoxide dismutase-3 (SOD3). We discuss how inflammatory activation of macrophages, in part through small GTPase Rab27A/B regulation of the secretory compartments, mediates the coalescence of these two proteins on the cell surface to deliver a focalized hydrogen peroxide output. In interplay with membrane-embedded oxidant transporters and redox sensitive target proteins, this arrangement allows for the autocrine and paracrine signaling, which govern macrophage activation states and transcriptional programs. By discussing examples of autocrine and paracrine redox signaling, we highlight why formation of spatiotemporal microenvironments where produced superoxide is rapidly converted to hydrogen peroxide and conveyed immediately to reach redox targets in proximal vicinity is required for efficient redox signaling. Finally, we discuss the recent discovery of macrophage-derived exosomes as vehicles of NOX2 holoenzyme export to other cells.

Peroxiredoxin-I Sustains Inflammation During Pancreatitis.

Peroxiredoxin-I Sustains Inflammation During Pancreatitis.

Discovery of new therapeutic redox targets for cardioprotection against ischemia/reperfusion injury and heart failure

Global epidemiological studies reported a shift from maternal/infectious communicable diseases to chronic non-communicable diseases and a major part is attributable to atherosclerosis and metabolic disorders. Accordingly, ischemic heart disease was identified as a leading risk factor for global mortality and morbidity with a prevalence of 128 million people. Almost 9 million premature deaths can be attributed to ischemic heart disease and subsequent acute myocardial infarction and heart failure, also representing a substantial socioeconomic burden. As evidenced by typical oxidative stress markers such as lipid peroxidation products or oxidized DNA/RNA bases, the formation of reactive oxygen species by various sources (NADPH oxidases, xanthine oxidase and mitochondrial resperatory chain) plays a central role for the severity of ischemia/reperfusion damage. The underlying mechanisms comprise direct oxidative damage but also adverse redox-regulation of kinase and calcium signaling, inflammation and cardiac remodeling among others. These processes and the role of reactive oxygen species are discussed in the present review. We also present and discuss potential targets for redox-based therapies that are either already established in the clinics (e.g. guanylyl cyclase activators and stimulators) or at least successfully tested in preclinical models of myocardial infarction and heart failure (mitochondria-targeted antioxidants). However, reactive oxygen species have not only detrimental effects but are also involved in essential cellular signaling and may even act protective as seen by ischemic pre- and post-conditioning or eustress – which makes redox therapy quite challenging.

MiR-320 is REDOX Sensitive and Targets Antioxidant Pathway During Myogenesis

miR-320 is REDOX Sensitive and Targets Antioxidant Pathway During Myogenesis