S-glutathionylation: from redox regulation of protein functions to human diseases

p63 affects distinct metabolic pathways during keratinocyte senescence, evaluated by metabolomic profile and gene expression analysis

Unraveling the molecular nature of skin aging and keratinocyte senescence represents a challenging research project in epithelial biology. In this regard, depletion of p63, a p53 family transcription factor prominently expressed in human and mouse epidermis, accelerates both aging and the onset of senescence markers in vivo animal models as well as in ex vivo keratinocytes. Nonetheless, the biochemical link between p63 action and senescence phenotype remains largely unexplored. In the present study, through ultrahigh performance liquid chromatography-tandem mass spectroscopy (UPLC-MS/MS) and gas chromatography/mass spectrometry (GC/MS) metabolomic analysis, we uncover interesting pathways linking replicative senescence to metabolic alterations during p63 silencing in human keratinocytes. Integration of our metabolomic profiling data with targeted transcriptomic investigation empowered us to demonstrate that absence of p63 and senescence share similar modulation profiles of oxidative stress markers, pentose phosphate pathway metabolites and lyso-glycerophospholipids, the latter due to enhanced phospholipases gene expression profile often under p63 direct/indirect gene control. Additional biochemical features identified in deranged keratinocytes include a relevant increase in lipids production, glucose and pyruvate levels as confirmed by upregulation of gene expression of key lipid synthesis and glycolytic enzymes, which, together with improved vitamins uptake, characterize senescence phenotype. Silencing of p63 in keratinocytes instead, translates into a blunted flux of metabolites through both glycolysis and the Krebs cycle, likely due to a p63-dependent reduction of hexokinase 2 and citrate synthase gene expression. Our findings highlight the potential role of p63 in counteracting keratinocyte senescence also through fine regulation of metabolite levels and relevant biochemical pathways. We believe that our research might contribute significantly to the discovery of new implications of p63 in keratinocyte senescence and related diseases.

Post-Translational Modifications to Cysteine Residues in Plant Proteins and Their Impact on the Regulation of Metabolism and Signal Transduction

Cys is one of the least abundant amino acids in proteins. However, it is often highly conserved and is usually found in important structural and functional regions of proteins. Its unique chemical properties allow it to undergo several post-translational modifications, many of which are mediated by reactive oxygen, nitrogen, sulfur, or carbonyl species. Thus, in addition to their role in catalysis, protein stability, and metal binding, Cys residues are crucial for the redox regulation of metabolism and signal transduction. In this review, we discuss Cys post-translational modifications (PTMs) and their role in plant metabolism and signal transduction. These modifications include the oxidation of the thiol group (S-sulfenylation, S-sulfinylation and S-sulfonylation), the formation of disulfide bridges, S-glutathionylation, persulfidation, S-cyanylation S-nitrosation, S-carbonylation, S-acylation, prenylation, CoAlation, and the formation of thiohemiacetal. For each of these PTMs, we discuss the origin of the modifier, the mechanisms involved in PTM, and their reversibility. Examples of the involvement of Cys PTMs in the modulation of protein structure, function, stability, and localization are presented to highlight their importance in the regulation of plant metabolic and signaling pathways.

Cysteine post-translational modifications regulate protein interactions of caveolin-3

Caveolae are small flask-shaped invaginations of the surface membrane which are proposed to recruit and co-localize signaling molecules. The distinctive caveolar shape is achieved by the oligomeric structural protein caveolin, of which three isoforms exist. Aside from the finding that caveolin-3 is specifically expressed in muscle, functional differences between the caveolin isoforms have not been rigorously investigated. Caveolin-3 is relatively cysteine-rich compared to caveolins 1 and 2, so we investigated its cysteine post-translational modifications. We find that caveolin-3 is palmitoylated at 6 cysteines and becomes glutathiolated following redox stress. We map the caveolin-3 palmitoylation sites to a cluster of cysteines in its C terminal membrane domain, and the glutathiolation site to an N terminal cysteine close to the region of caveolin-3 proposed to engage in protein interactions. Glutathiolation abolishes caveolin-3 interaction with heterotrimeric G protein alpha subunits. Our results indicate that a caveolin-3 oligomer contains up to 66 palmitates, compared to up to 33 for caveolin-1. The additional palmitoylation sites in caveolin-3 therefore provide a mechanistic basis by which caveolae in smooth and striated muscle can possess unique phospholipid and protein cargoes. These unique adaptations of the muscle-specific caveolin isoform have important implications for caveolar assembly and signaling.

Glutathionyl Hemoglobin and Its Emerging Role as a Clinical Biomarker of Chronic Oxidative Stress

Hemoglobin is one of the proteins that are more susceptible to S-glutathionylation and the levels of its modified form, glutathionyl hemoglobin (HbSSG), increase in several human pathological conditions. The scope of the present review is to provide knowledge about how hemoglobin is subjected to S-glutathionylation and how this modification affects its functionality. The different diseases that showed increased levels of HbSSG and the methods used for its quantification in clinical investigations will be also outlined. Since there is a growing need for precise and reliable methods for markers of oxidative stress in human blood, this review highlights how HbSSG is emerging more and more as a good indicator of severe oxidative stress but also as a key pathogenic factor in several diseases.

Bacillus subtilis YtpP and Thioredoxin A Are New Players in the Coenzyme-A-Mediated Defense Mechanism against Cellular Stress

Coenzyme A (CoA) is an important cellular metabolite that is critical for metabolic processes and the regulation of gene expression. Recent discovery of the antioxidant function of CoA has highlighted its protective role that leads to the formation of a mixed disulfide bond with protein cysteines, which is termed protein CoAlation. To date, more than 2000 CoAlated bacterial and mammalian proteins have been identified in cellular responses to oxidative stress, with the majority being involved in metabolic pathways (60%). Studies have shown that protein CoAlation is a widespread post-translational modification which modulates the activity and conformation of the modified proteins. The induction of protein CoAlation by oxidative stress was found to be rapidly reversed after the removal of oxidizing agents from the medium of cultured cells. In this study, we developed an enzyme-linked immunosorbent assay (ELISA)-based deCoAlation assay to detect deCoAlation activity from Bacillus subtilis and Bacillus megaterium lysates. We then used a combination of ELISA-based assay and purification strategies to show that deCoAlation is an enzyme-driven mechanism. Using mass-spectrometry and deCoAlation assays, we identified B. subtilis YtpP (thioredoxin-like protein) and thioredoxin A (TrxA) as enzymes that can remove CoA from different substrates. With mutagenesis studies, we identified YtpP and TrxA catalytic cysteine residues and proposed a possible deCoAlation mechanism for CoAlated methionine sulfoxide reducatse A (MsrA) and peroxiredoxin 5 (PRDX5) proteins, which results in the release of both CoA and the reduced form of MsrA or PRDX5. Overall, this paper reveals the deCoAlation activity of YtpP and TrxA and opens doors to future studies on the CoA-mediated redox regulation of CoAlated proteins under various cellular stress conditions.

Glutathione-Related Enzymes and Proteins: A Review

The tripeptide glutathione is found in all eukaryotic cells, and due to the compartmentalization of biochemical processes, its synthesis takes place exclusively in the cytosol. At the same time, its functions depend on its transport to/from organelles and interorgan transport, in which the liver plays a central role. Glutathione is determined as a marker of the redox state in many diseases, aging processes, and cell death resulting from its properties and reactivity. It also uses other enzymes and proteins, which enables it to engage and regulate various cell functions. This paper approximates the role of these systems in redox and detoxification reactions such as conjugation reactions of glutathione-S-transferases, glyoxylases, reduction of peroxides through thiol peroxidases (glutathione peroxidases, peroxiredoxins) and thiol-disulfide exchange reactions catalyzed by glutaredoxins.

Intranasal administration of polysulfide prevents neurodegeneration in spinal cord and rescues mice from delayed paraplegia after spinal cord ischemia

BACKGROUND

Delayed paraplegia is a devastating complication of thoracoabdominal aortic surgery. Hydrogen sulfide (H₂S) was reported to be protective in a mouse model of spinal cord ischemia and the beneficial effect of H₂S has been attributed to polysulfides. The objective of this study was to investigate the effects of polysulfides on delayed paraplegia after spinal cord ischemia.

METHODS AND RESULTS

Spinal cord ischemia was induced in male and female C57BL/6J mice by clamping the aortic arch and the left subclavian artery. Glutathione trisulfide (GSSSG), glutathione (GSH), glutathione disulfide (GSSG), or vehicle alone was administered intranasally at 0, 8, 23, and 32 h after surgery. All mice treated with vehicle alone developed paraplegia within 48 h after surgery. GSSSG, but not GSH or GSSG, prevented paraplegia in 8 of 11 male mice (73%) and 6 of 8 female mice (75%). Intranasal administration of ³⁴S-labeled GSSSG rapidly increased ³⁴S-labeled sulfane sulfur species in the lumbar spinal cord. In mice treated with intranasal GSSSG, there were increased sulfane sulfur levels, and decreased neurodegeneration, microglia activation, and caspase-3 activation in the lumbar spinal cord. In vitro studies using murine primary cortical neurons showed that GSSSG increased intracellular levels of sulfane sulfur. GSSSG, but not GSH or GSSG, dose-dependently improved cell viability after oxygen and glucose deprivation/reoxygenation (OGD/R). Pantethine trisulfide (PTN-SSS) also increased intracellular sulfane sulfur and improved cell viability after OGD/R. Intranasal administration of PTN-SSS, but not pantethine, prevented paraplegia in 6 of 9 male mice (66%).

CONCLUSIONS

Intranasal administration of polysulfides rescued mice from delayed paraplegia after transient spinal cord ischemia. The neuroprotective effects of GSSSG were associated with increased levels of polysulfides and sulfane sulfur in the lumbar spinal cord. Targeted delivery of sulfane sulfur by polysulfides may prove to be a novel approach to the treatment of neurodegenerative diseases.

Antioxidant Defense and Pseudoexfoliation Syndrome: An Updated Review

Oxidative stress (OS) affects the anterior ocular tissues, rendering them susceptible to several eye diseases. On the other hand, protection of the eye from harmful factors is achieved by unique defense mechanisms, including enzymatic and non-enzymatic antioxidants. The imbalance between oxidants and antioxidants could be the cause of pseudoexfoliation syndrome (PEXS), a condition of defective extracellular matrix (ECM) remodeling. A systematic English-language literature review was conducted from May 2022 to June 2022. The main antioxidant enzymes protecting the eye from reactive oxygen species (ROS) are superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), which catalyze the reduction of specific types of ROS. Similarly, non-enzymatic antioxidants such as vitamins A, E and C, carotenoids and glutathione (GSH) are involved in removing ROS from the cells. PEXS is a genetic disease, however, environmental and dietary factors also influence its development. Additionally, many OS products disrupting the ECM remodeling process and modifying the antioxidative defense status could lead to PEXS. This review discusses the antioxidative defense of the eye in association with PEXS, and the intricate link between OS and PEXS. Understanding the pathways of PEXS evolution, and developing new methods to reduce OS, are crucial to control and treat this disease. However, further studies are required to elucidate the molecular pathogenesis of PEXS.

Ackee (Blighia sapida K.D. Koenig) Leaves and Arils Methanolic Extracts Ameliorate CdCl2-Induced Oxidative Stress Biomarkers in Drosophila melanogaster

Different ethnomedical benefits have been documented on different parts of Ackee (Blighia sapida); however, their roles in ameliorating oxidative damages are not well established. CdCl2 inhibitory effects on some oxidative-stress biomarkers and ameliorative potentials of Ackee leaves (AL) and arils (AS) methanolic extracts were studied using Drosophila melanogaster as a model. One to 3-day-old D. melanogaster flies were orally exposed to different concentrations of CdCl2 in their diet for 7 days. The fly's survival profile and negative geotaxis assays were subsequently analysed. Methanolic extracts of AL and AS treatments showed negative geotaxis behaviour, and extracts were able to ameliorate the effect of Cd2+ on catalase and GST activities and increase total thiol and GSH levels, while it reduced the H2O2 generation (p ≤ 0.05) when compared to the control. Furthermore, Cd2+ exhibited noncompetitive and uncompetitive enzyme inhibition on catalase and GST activities, respectively, which may have resulted in the formation of Enzyme-substrate-Cd2+ transition complexes, thus inhibiting the conversion of substrate to product. This study, thus, suggests that the Cd2+ mechanism of toxicity was associated with oxidative damage, as evidenced by the alteration in the oxidative stress-antioxidant imbalance, and that the AL and AS extracts possess essential phytochemicals that could alleviate possibly deleterious oxidative damage effects of environmental pollutants such as CdCl2. Thus, Ackee plant parts possess essential phytonutrients which could serve as valuable resources in heavy metal toxicity management.

Enduring Reactive Oxygen Species Emission Causes Aberrant Protein S-Glutathionylation Transitioning Human Aortic Valve Cells from a Sclerotic to a Stenotic Phenotype

Aims: During calcific aortic valve stenosis (CAVS) progression, oxidative stress and endothelial dysfunction mark the initial pathogenic steps with a parallel dysregulation of the antioxidant systems. Here, we tested whether oxidation-induced protein S-glutathionylation (P-SSG) accounts for a phenotypic switch in human aortic valvular tissue, eventually leading to calcium deposition. Next, we tested whether countering this reactive oxygen species (ROS) surge would prevent these perturbations. Results: We employed state-of-the-art technologies, such as electron paramagnetic resonance (EPR), liquid chromatography-tandem mass spectrometry, imaging flow-cytometry, and live-cell imaging on human excised aortic valves and primary valve endothelial cells (VECs). We observed that a net rise in EPR-detected ROS emission marked the transition from fibrotic to calcific in human CAVS specimens, coupled to a progressive increment in P-SSG deposition. In human VECs (hVECs), treatment with 2-acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylthiocarbonylamino)phenylthiocarbamoylsulfanyl]propionic acid triggered highly oxidizing conditions prompting P-SSG accumulation, damaging mitochondria, and inducing endothelial nitric oxide synthase uncoupling. All the events conjured up in morphing these cells from their native endothelial phenotype into a damaged calcification-inducing one. As proof of principle, the use of the antioxidant N-acetyl-L-cysteine prevented these alterations. Innovation: Borne as a compensatory system to face excessive oxidative burden, with time, P-SSG contributes to the morphing of hVECs from their innate phenotype into a damaged one, paving the way to calcium deposition. Conclusion: Our data suggest that, in the human aortic valve, unremitted ROS emission along with a P-SSG build-up occurs and accounts, at least in part, for the morphological/functional changes leading to CAVS. Antioxid. Redox Signal. 37, 1051-1071.

Effects of Social Isolation on the Development of Anxiety and Depression-Like Behavior in Model Experiments in Animals

This review describes the role of social isolation in the development of anxiety and depression-like behavior in rodents. The duration of social isolation, age from onset of social isolation, sex, species, and strain of animals, the nature of the model used, and other factors have been shown to have influences. The molecular-cellular mechanisms of development of anxiety and depression-like behavior under the influence of social isolation and the roles of the HHAS, oxidative and nitrosative stress, neuroinflammation, BDNF, neurogenesis, synaptic plasticity, as well as monoamines in these mechanisms are discussed. This review presents data on sex differences in the effects of social isolation, along with the effects of interactions with other types of stress, and the roles of an enriched environment and other factors in ameliorating the negative sequelae of social isolation.

Galectin-3 S-glutathionylation regulates its effect on adipocyte insulin signaling

Protein-S-glutathionylation promotes redox signaling in physiological and oxidative distress conditions. Galectin-3 (Gal-3) promotes insulin resistance by down-regulating adipocyte insulin signaling, however, its S-glutathionylation and significance is not known. In this context, we report reversible S-glutathionylation of Gal-3. Site-directed mutagenesis established Gal-3 Cys187 as the putative S-glutathionylation site. Glutathionylated Gal-3 prevents Gal-3(WT)-Insulin Receptor interaction and facilitates insulin-induced murine adipocyte p-IRS1(tyr895) and p-AKT(ser473) signaling and glucose uptake in a Gal-3 Cys187 glutathionylation dependent manner in murine adipocytes, as assessed by Western blotting and 2-NBDG uptake assay respectively. Pre-glutathionylated Gal-3 at Cys187 resisted irreversible oxidation by H₂O₂. M2 macrophages showed enhanced Gal-3 S-glutathionylation when compared to M1 phenotype. Serum and stromal vascular fraction (SVF) isolated from control mice showed increased Gal-3 S-glutathionylation as compared to db/db mice. A significant increase in Gal-3 S-glutathionylation was observed in metformin-treated db/db mice when compared to db/db mice alone. Similar to murine, enhanced Gal-3 S-glutathionylation is observed in primary human monocyte derived M2 macrophages when compared to the M1 macrophage phenotype and Gal-3 regulates primary human adipocyte insulin signaling in a glutathionylation dependent manner. Collectively, we identified Gal-3 S-glutathionylation as a protective phenomenon, which relieves its inhibitory effect on adipocyte insulin signaling.

Cysteine trisulfide oxidizes protein thiols and induces electrophilic stress in human cells

The cellular effects of hydrogen sulfide (H₂S) signaling may be partially mediated by the formation of alkyl persulfides from thiols, such as glutathione and protein cysteine residues. Persulfides are potent nucleophiles and reductants and therefore potentially an important endogenous antioxidant or protein post-translational modification. To directly study the cellular effects of persulfides, cysteine trisulfide (Cys-S₃) has been proposed as an in situ persulfide donor, as it reacts with cellular thiols to generate cysteine persulfide (Cys-S-S^-). Numerous pathways sense and respond to electrophilic cellular stressors to inhibit cellular proliferation and induce apoptosis, however the effect of Cys-S₃ on the cellular stress response has not been addressed. Here we show that Cys-S₃ inhibited cellular metabolism and proliferation and rapidly induced cellular- and ER-stress mechanisms, which were coupled to widespread protein-thiol oxidation. Cys-S₃ reacted with Na₂S to generate cysteine persulfide, which protected human cell lines from ER-stress. However this method of producing cysteine persulfide contains excess sulfide, which interferes with the direct analysis of persulfide donation. We conclude that cysteine trisulfide is a thiol oxidant that induces cellular stress and decreased proliferation.

Glutathione Metabolism in Plants under Stress: Beyond Reactive Oxygen Species Detoxification

Glutathione is an essential metabolite for plant life best known for its role in the control of reactive oxygen species (ROS). Glutathione is also involved in the detoxification of methylglyoxal (MG) which, much like ROS, is produced at low levels by aerobic metabolism under normal conditions. While several physiological processes depend on ROS and MG, a variety of stresses can dramatically increase their concentration leading to potentially deleterious effects. In this review, we examine the structure and the stress regulation of the pathways involved in glutathione synthesis and degradation. We provide a synthesis of the current knowledge on the glutathione-dependent glyoxalase pathway responsible for MG detoxification. We present recent developments on the organization of the glyoxalase pathway in which alternative splicing generate a number of isoforms targeted to various subcellular compartments. Stress regulation of enzymes involved in MG detoxification occurs at multiple levels. A growing number of studies show that oxidative stress promotes the covalent modification of proteins by glutathione. This post-translational modification is called S-glutathionylation. It affects the function of several target proteins and is relevant to stress adaptation. We address this regulatory function in an analysis of the enzymes and pathways targeted by S-glutathionylation.

Glutathione in the Brain

Glutathione (GSH) is the most abundant non-protein thiol, and plays crucial roles in the antioxidant defense system and the maintenance of redox homeostasis in neurons. GSH depletion in the brain is a common finding in patients with neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease, and can cause neurodegeneration prior to disease onset. Excitatory amino acid carrier 1 (EAAC1), a sodium-dependent glutamate/cysteine transporter that is selectively present in neurons, plays a central role in the regulation of neuronal GSH production. The expression of EAAC1 is posttranslationally controlled by the glutamate transporter-associated protein 3–18 (GTRAP3-18) or miR-96-5p in neurons. The regulatory mechanism of neuronal GSH production mediated by EAAC1 may be a new target in therapeutic strategies for these neurodegenerative diseases. This review describes the regulatory mechanism of neuronal GSH production and its potential therapeutic application in the treatment of neurodegenerative diseases.

Function and Regulation of Chloroplast Peroxiredoxin IIE

Peroxiredoxins (PRX) are thiol peroxidases that are highly conserved throughout all biological kingdoms. Increasing evidence suggests that their high reactivity toward peroxides has a function not only in antioxidant defense but in particular in redox regulation of the cell. Peroxiredoxin IIE (PRX-IIE) is one of three PRX types found in plastids and has previously been linked to pathogen defense and protection from protein nitration. However, its posttranslational regulation and its function in the chloroplast protein network remained to be explored. Using recombinant protein, it was shown that the peroxidatic Cys121 is subjected to multiple posttranslational modifications, namely disulfide formation, S-nitrosation, S-glutathionylation, and hyperoxidation. Slightly oxidized glutathione fostered S-glutathionylation and inhibited activity in vitro. Immobilized recombinant PRX-IIE allowed trapping and subsequent identification of interaction partners by mass spectrometry. Interaction with the 14-3-3 υ protein was confirmed in vitro and was shown to be stimulated under oxidizing conditions. Interactions did not depend on phosphorylation as revealed by testing phospho-mimicry variants of PRX-IIE. Based on these data it is proposed that 14-3-3υ guides PRX‑IIE to certain target proteins, possibly for redox regulation. These findings together with the other identified potential interaction partners of type II PRXs localized to plastids, mitochondria, and cytosol provide a new perspective on the redox regulatory network of the cell.

Role of oxidative stress in the dysfunction of the placental endothelial nitric oxide synthase in preeclampsia

Preeclampsia (PE) is a multifactorial pregnancy disease, characterized by new-onset gestational hypertension with (or without) proteinuria or end-organ failure, exclusively observed in humans. It is a leading cause of maternal morbidity affecting 3–7% of pregnant women worldwide. PE pathophysiology could result from abnormal placentation due to a defective trophoblastic invasion and an impaired remodeling of uterine spiral arteries, leading to a poor adaptation of utero-placental circulation. This would be associated with hypoxia/reoxygenation phenomena, oxygen gradient fluctuations, altered antioxidant capacity, oxidative stress, and reduced nitric oxide (NO) bioavailability. This results in part from the reaction of NO with the radical anion superoxide (O₂^•−), which produces peroxynitrite ONOO^-, a powerful pro-oxidant and inflammatory agent. Another mechanism is the progressive inhibition of the placental endothelial nitric oxide synthase (eNOS) by oxidative stress, which results in eNOS uncoupling via several events such as a depletion of the eNOS substrate L-arginine due to increased arginase activity, an oxidation of the eNOS cofactor tetrahydrobiopterin (BH4), or eNOS post-translational modifications (for instance by S-glutathionylation). The uncoupling of eNOS triggers a switch of its activity from a NO-producing enzyme to a NADPH oxidase-like system generating O₂^•−, thereby potentiating ROS production and oxidative stress. Moreover, in PE placentas, eNOS could be post-translationally modified by lipid peroxidation-derived aldehydes such as 4-oxononenal (ONE) a highly bioreactive agent, able to inhibit eNOS activity and NO production. This review summarizes the dysfunction of placental eNOS evoked by oxidative stress and lipid peroxidation products, and the potential consequences on PE pathogenesis.

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Physiological ROS production is enhanced during pregnancy.

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eNOS is one of the main target of oxidative stress in PE placenta.

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eNOS is S-glutathionylated in PE placentas.

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eNOS is modified by lipid oxidation products in PE placentas.

[Mechanism of glutathione production in neurons]

Glutathione (GSH) is a tripeptide consisting of glutamate, cysteine, and glycine that acts as an important neuroprotective molecule in the central nervous system. In neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease, GSH levels in the brain would be decreased before the onset, and GSH dysregulation is considered to be involved in the development of these neurodegenerative diseases. Cysteine uptake into neurons is the rate-limiting step for GSH synthesis. Excitatory amino acid carrier 1 (EAAC1), which is a glutamate/cysteine cotransporter, is responsible for the neuronal cysteine uptake, and EAAC1 dysfunction reduces GSH levels in the brain and has a significant influence on the process of neurodegeneration. Since miR-96-5p, which is one of microRNAs, suppresses EAAC1 expression, it is conceivable that miR-96-5p inhibitor suppresses the onset or slows the progression of neurodegenerative diseases by increasing EAAC1 levels leading to promoting neuronal GSH production.

Comparative proteomic analysis identifies biomarkers for renal aging

Proteomics have long been applied into characterization of molecular signatures in aging. Due to different methods and instrumentations employed for proteomic analysis, inter-dataset validation needs to be performed to identify potential biomarkers for aging. In this study, we used comparative proteomics analysis to profile age-associated changes in proteome and glutathionylome in mouse kidneys. We identified 108 proteins that were differentially expressed in young and aged mouse kidneys in three different datasets; from these, 27 proteins were identified as potential renal aging biomarkers, including phosphoenolpyruvate carboxykinase (Pck1), CD5 antigen-like protein (Cd5l), aldehyde dehydrogenase 1 (Aldh1a1), and uromodulin. Our results also showed that peroxisomal proteins were significantly downregulated in aged mice, whereas IgGs were upregulated, suggesting that peroxisome deterioration might be a hallmark for renal aging. Glutathionylome analysis demonstrated that downregulation of catalase and glutaredoxin-1 (Glrx1) significantly increased protein glutathionylation in aged mice. In addition, nicotinamide mononucleotide (NMN) administration significantly increased the number of peroxisomes in aged mouse kidneys, indicating that NMN enhanced peroxisome biogenesis, and suggesting that it might be beneficial to reduce kidney injuries. Together, our data identify novel potential biomarkers for renal aging, and provide a valuable resource for understanding the age-associated changes in kidneys.

Behaviour of carbonyl groups in several clinical conditions: Analysis of our survey

Protein carbonylation is a marker of oxidative protein damage, that is likely involved in the pathogenesis of several diseases. The aim of this study was to evaluate the protein carbonyl (PC) groups in different clinical conditions. It included different groups of subjects: 81 trained subjects; 23 subjects with mild essential hypertension; 31 middle-aged subjects with metabolic syndrome (MS); 106 subjects with MS not selected for age (subdivided into two subgroups, with and without diabetes mellitus); 91 obese adults subdivided in two subgroups (BMI 30-35 Kg/m2 and BMI > 35 kg/m2); 48 subjects with obstructive sleep apnea syndrome (OSAS) subdivided in accordance with the apnea/hypopnea index (AHI); 27 subjects with chronic kidney disease (CKD) on conservative therapy; 31 subjects with CKD on haemodialysis treatment; and 50 subjects with juvenile myocardial infarction. PC groups were reduced in trained subjects in comparison with sedentary controls, while no variation was observed in mild essential hypertension. PC groups were increased in MS subjects and in adult obese subjects. In MS subjects the PC groups were not influenced by the presence of diabetes mellitus and in adult obese subjects were not influenced by the obesity degree. In OSAS subjects only those with AHI > 30 showed an increase of PC groups. PC groups increased in CKD subjects undergoing conservative treatment and haemodialysis therapy. In dialyzed subjects, after a standard dialysis session, there was a marked increase in PC groups. In juvenile myocardial infarction PC groups were higher than in controls; there was no difference between STEMI and NSTEMI and their concentration was unaffected by the number of cardiovascular risk factors or stenosed coronary vessels.

Pterostilbene improves cardiac function in a rat model of right heart failure through modulation of calcium handling proteins and oxidative stress

This study explored the effect of pterostilbene (PTS) complexed with hydroxypropyl-β-cyclodextrin (HPβCD) on right heart function, glutathione and glutaredoxin systems, and the expression of redox-sensitive proteins involved with regulation calcium levels in the experimental model of pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). After 7 days of PAH induction, rats received daily doses of the PTS:HPβCD complex (corresponding to 25, 50, or 100 mg·kg^-1 of PTS) or vehicle (control group, CTR0) (an aqueous solution containing HPβCD; CTR0 and MCT0 (MCT group that did not receive PTS treatment)) via oral administration for 2 weeks. The results showed that the PTS:HPβCD complex increased the content of reduced glutathione and the activity of glutathione-S-transferase and glutaredoxin in the right ventricle (RV) of MCT-treated rats in a dose-dependent manner. Additionally, at higher doses, it also prevented the reduction of stroke volume and cardiac output, prevented myocardial performance index (MPI) increase, reduced lipoperoxidation, reduced total phospholamban, and increased the expression of sarcoplasmic reticulum calcium ATPase in the RV of MCT-treated rats. These results demonstrate that the PTS:HPβCD complex has a dose-dependent antioxidant mechanism that results in improved cardiac function in experimental right heart failure. Our results open a field of possibilities to PTS administration as new therapeutic approach to conventional therapy for right ventricular dysfunction. Novelty Pterostilbene complexed with hydroxypropyl-β-cyclodextrin could be a new therapeutic approach. Pterostilbene complexed with hydroxypropyl-β-cyclodextrin reestablishes redox homeostasis through glutathione metabolism modulation, leading to an improved MPI in pulmonary arterial hypertension-provoked right heart failure.

Oxidative Stress in Pulmonary Fibrosis

Oxidative stress has been linked to various disease states as well as physiological aging. The lungs are uniquely exposed to a highly oxidizing environment and have evolved several mechanisms to attenuate oxidative stress. Idiopathic pulmonary fibrosis (IPF) is a progressive age-related disorder that leads to architectural remodeling, impaired gas exchange, respiratory failure, and death. In this article, we discuss cellular sources of oxidant production, and antioxidant defenses, both enzymatic and nonenzymatic. We outline the current understanding of the pathogenesis of IPF and how oxidative stress contributes to fibrosis. Further, we link oxidative stress to the biology of aging that involves DNA damage responses, loss of proteostasis, and mitochondrial dysfunction. We discuss the recent findings on the role of reactive oxygen species (ROS) in specific fibrotic processes such as macrophage polarization and immunosenescence, alveolar epithelial cell apoptosis and senescence, myofibroblast differentiation and senescence, and alterations in the acellular extracellular matrix. Finally, we provide an overview of the current preclinical studies and clinical trials targeting oxidative stress in fibrosis and potential new strategies for future therapeutic interventions. © 2020 American Physiological Society. Compr Physiol 10:509-547, 2020.

Hyaluronan-binding protein 1 (HABP1) overexpression triggers induction of senescence in fibroblasts cells

Hyaluronan-binding protein 1 (HABP1), a multi-compartmental, multi-functional protein has a wide range of functions, which can be attributed to its ability to associate with a variety of cellular ligands. Earlier we have reported that HABP1 overexpression in rat normal fibroblasts (F-HABP07) shows chronic generation of reactive oxygen species (ROS), induction of autophagy, and apoptosis. However, a significant proportion of cells remained viable after the majority went through apoptosis from 60 to 72 h. In this study, an attempt has been made to delineate the cellular events in the declined population of surviving cells. It has been elucidated here that, these cells at later time points of growth, that is, 72 and 84 h, not only appeared to shrink but also are devoid of autophagic vacuoles and displayed polyploidy. F-HABP07 cells exhibited an altered cytoskeletal structure from their parental cell line F111, assumed to be caused upon inhibition of actin polymerization and decrease in IQ motif-containing GTPase activating protein 1 (IQGAP1), a key protein associated with maintenance of cytoskeletal integrity. Enhanced expression and nuclear localization of AKT observed in F-HABP07 cells appears to be contributing toward the maintenance of high ROS levels in these cells and also potentially modulating the IQGAP1 activity. These observations, in fact have been considered to result in sustained DNA damage, which then leads to increased expression of p53 and activation of p21 and carry out the cellular events responsible for senescence. Subsequent assessment of the presence of positive β-gal staining and enhanced expression of p16^INK4a in F-HABP07, confirmed that HABP1 overexpressing fibroblasts undergo senescence.

Immunoprecipitation methods to identify S-glutathionylation in target proteins

S-glutathionylation is a reversible post-translational modification of proteins that generate a mixed disulfide between glutathione to thiolate anion of cysteine residues in target proteins. In the last ten years, S-glutathionylation has been extensively studied since it represents the cellular response to oxidative stress, in physiological as well as pathological conditions. This modification may be a protective mechanism from irreversible oxidative damage and, on the other hand, may modulate protein folding and function. Due to the importance of S-glutathionylation in cellular redox signaling, various methods have been developed to identify S-gluthationylated proteins. Herein, we describe two easy methods to recognized S-glutathionylation of a target protein after oxidative stress in cellular extracts based on different immunoprecipitation procedures. The immunoprecipitation assay allows the capture of one glutathionylated protein using a specific antibody that binds to the target protein. The presence of S-glutathionylation in the immunoprecipitated protein is identified using anti-glutathione antibody. The second type of approach is based on the detection of the glutathionylated protein with biotin/streptavidin technique. After different steps of protection of non-oxidized thiolic groups and reduction of S-glutathionylated groups, the newly-formed protein free-thiols are labeled with biotin-GSH. The modified protein can be isolate with streptavidin-beads and recognized using an antibody against target protein. •S-glutathionylation is a reversible post-translational modification of proteins that recently has been emerged as important signaling in the redox regulation of protein function.•Both methods to identify glutathionylated proteins are economic, easy and do not require particular equipment.•The setups of both methods guarantee high reproducibility.

Role of Glutathionylation in Infection and Inflammation

Glutathionylation, that is, the formation of mixed disulfides between protein cysteines and glutathione (GSH) cysteines, is a reversible post-translational modification catalyzed by different cellular oxidoreductases, by which the redox state of the cell modulates protein function. So far, most studies on the identification of glutathionylated proteins have focused on cellular proteins, including proteins involved in host response to infection, but there is a growing number of reports showing that microbial proteins also undergo glutathionylation, with modification of their characteristics and functions. In the present review, we highlight the signaling role of GSH through glutathionylation, particularly focusing on microbial (viral and bacterial) glutathionylated proteins (GSSPs) and host GSSPs involved in the immune/inflammatory response to infection; moreover, we discuss the biological role of the process in microbial infections and related host responses.

Metabolic adaptation of short-living growth hormone transgenic mice to methionine restriction and supplementation

Extension of mammalian health and life span has been achieved using various dietary interventions. We previously reported that restricting dietary methionine (MET) content extends life span only when growth hormone signaling is intact (no life span increase in GH deficiency or GH resistance). To understand the metabolic responses of altered dietary MET in the context of accelerated aging (high GH), the current study evaluated MET and related pathways in short-living GH transgenic (GH Tg) and wild-type mice following 8 weeks of restricted (0.16%), low (0.43%), or enriched (1.3%) MET consumption. Liver MET metabolic enzymes were suppressed in GH Tg compared to diet-matched wild-type mice. MET metabolite levels were differentially affected by GH status and diet. SAM:SAH ratios were markedly higher in GH Tg mice. Glutathione levels were lower in both genotypes consuming 0.16% MET but reduced in GH Tg mice when compared to wild type. Tissue thioredoxin and glutaredoxin were impacted by diet and GH status. The responsiveness to the different MET diets is reflected across many metabolic pathways indicating the importance of GH signaling in the ability to discriminate dietary amino acid levels and alter metabolism and life span.

Alzheimer's Pathogenesis, Metal-Mediated Redox Stress, and Potential Nanotheranostics

Alzheimer's disease (AD) characterized by insoluble amyloid-β (Aβ) deposits, neurofibrillary tangles (NFTs), and neuronal demise. The influence of environmental and genetic factors on AD progression remains elusive, however evidence suggests biometal dyshomeostasis elicits neuronal death, neuroinflammation, and accumulated oxidative damages in AD brain. As such, three pathways have been identified that result from abnormal biometal accumulation and increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in AD brain parenchyma: (1) the damage caused by direct oxidation of cellular components such as DNA and proteins; (2) the oligomerization of Aβ and NFTs, and (3) the promotion of apoptosis through NF-κB signaling pathway. Finally, given recent developments in nanotechnology, we have briefly reviewed potential nanotheranostic agents as potential AD theranostics.

Phanerochaete chrysosporium as a model organism to assess the toxicity of municipal landfill leachate from Elazığ, Turkey

In order to evaluate the potential ecological risk and the toxic effect of landfill leachate (LL), Phanerochaete chrysosporium was exposed to LL and their biochemical response was observed by using antioxidant parameters. Phanerochaete chrysosporium, ME 446, was kept at 4 °C after being sub-cultured at 28 °C on Sabouraud Dextrose Agar (SDA). Superoxide dismutase (SOD), catalase (CAT) activities, and malaondialdehyde (MDA) and glutathione (GSH) levels of P. chrysosporium exposed to different dilution rates of leachate (1/10 and 1/20) for 24 and 96 h were analyzed by using the ELISA method. The physiochemical parameters such as pH, conductivity, total dissolved solids (TDS), dissolved oxygen (DO), chemical oxygen demand (COD) of leachate, and reference water were analyzed by using the YSI Professional Plus handheld multiparameter meter. In this study, SOD activities were decreased in the application groups compared with the Control Group at the 24th and 96th hours. CAT activities and GSH levels increased in the application groups compared with the Control Group at the 24th hour but decreased at the 96th hours. MDA levels increased in all of the application groups when compared with the Control Group for both 24 and 96 h. Different concentration of LL induces oxidative stress in P. chrysosporium, increased CAT activity and MDA levels, and decreased SOD activity and GSH levels.

Glutathione-related substances maintain cardiomyocyte contractile function in hypoxic conditions

Severe hypoxia leads to decline in cardiac contractility and induces arrhythmic events in part due to oxidative damage to cardiomyocyte proteins including ion transporters. This results in compromised handling of Ca2+ ions that trigger heart contractile machinery. Here, we demonstrate that thiol-containing compounds such as N-acetylcysteine (NAC), glutathione ethyl ester (et-GSH), oxidized tetraethylglutathione (tet-GSSG), oxidized glutathione (GSSG) and S-nitrosoglutathione (GSNO) are capable of reducing negative effects of hypoxia on isolated rat cardiomyocytes. Preincubation of cardiomyocytes with 0.1 mM GSNO, 0.5 mM et-GSH, GSSG, tet-GSSG or with 10 mM NAC allows cells 5-times longer tolerate the hypoxic conditions and elicit regular Ca2+ transients in response to electric pacing. The shape of Ca2+ transients generated in the presence of GSNO, et-GSH and NAC was similar to that observed in normoxic control cardiomyocytes. The leader compound, GSNO, accelerated by 34% the recovery of normal contractile function of isolated rat heart subjected to ischemia-reperfusion. GSNO increased glutathionylation of Na,K-ATPase alpha-2 subunit, the principal ion-transporter of cardiac myocyte sarcolemma, which prevents irreversible oxidation of Na,K-ATPase and regulates its function to support normal Ca2+ ion handling in hypoxic cardiomyocytes. Altogether, GSNO appears effective cardioprotector in hypoxic conditions worth further studies toward its cardiovascular application.

Glycolysis-Derived Compounds From Astrocytes That Modulate Synaptic Communication

Based on the concept of the tripartite synapse, we have reviewed the role of glucose-derived compounds in glycolytic pathways in astroglial cells. Glucose provides energy and substrate replenishment for brain activity, such as glutamate and lipid synthesis. In addition, glucose metabolism in the astroglial cytoplasm results in products such as lactate, methylglyoxal, and glutathione, which modulate receptors and channels in neurons. Glucose has four potential destinations in neural cells, and it is possible to propose a crossroads in “X” that can be used to describe these four destinations. Glucose-6P can be used either for glycogen synthesis or the pentose phosphate pathway on the left and right arms of the X, respectively. Fructose-6P continues through the glycolysis pathway until pyruvate is formed but can also act as the initial compound in the hexosamine pathway, representing the left and right legs of the X, respectively. We describe each glucose destination and its regulation, indicating the products of these pathways and how they can affect synaptic communication. Extracellular L-lactate, either generated from glucose or from glycogen, binds to HCAR1, a specific receptor that is abundantly localized in perivascular and post-synaptic membranes and regulates synaptic plasticity. Methylglyoxal, a product of a deviation of glycolysis, and its derivative D-lactate are also released by astrocytes and bind to GABA_A receptors and HCAR1, respectively. Glutathione, in addition to its antioxidant role, also binds to ionotropic glutamate receptors in the synaptic cleft. Finally, we examined the hexosamine pathway and evaluated the effect of GlcNAc-modification on key proteins that regulate the other glucose destinations.

KRIT1 Loss-Of-Function Associated with Cerebral Cavernous Malformation Disease Leads to Enhanced S-Glutathionylation of Distinct Structural and Regulatory Proteins

Loss-of-function mutations in the KRIT1 gene are associated with the pathogenesis of cerebral cavernous malformations (CCMs), a major cerebrovascular disease still awaiting therapies. Accumulating evidence demonstrates that KRIT1 plays an important role in major redox-sensitive mechanisms, including transcriptional pathways and autophagy, which play major roles in cellular homeostasis and defense against oxidative stress, raising the possibility that KRIT1 loss has pleiotropic effects on multiple redox-sensitive systems. Using previously established cellular models, we found that KRIT1 loss-of-function affects the glutathione (GSH) redox system, causing a significant decrease in total GSH levels and increase in oxidized glutathione disulfide (GSSG), with a consequent deficit in the GSH/GSSG redox ratio and GSH-mediated antioxidant capacity. Redox proteomic analyses showed that these effects are associated with increased S-glutathionylation of distinct proteins involved in adaptive responses to oxidative stress, including redox-sensitive chaperonins, metabolic enzymes, and cytoskeletal proteins, suggesting a novel molecular signature of KRIT1 loss-of-function. Besides providing further insights into the emerging pleiotropic functions of KRIT1, these findings point definitively to KRIT1 as a major player in redox biology, shedding new light on the mechanistic relationship between KRIT1 loss-of-function and enhanced cell sensitivity to oxidative stress, which may eventually lead to cellular dysfunctions and CCM disease pathogenesis.

Characterization of residue-specific glutathionylation of CSF proteins in multiple sclerosis - A MS-based approach

Reduction of a disulfide linkage between cysteine residues in proteins, a standard step in the preanalytical preparation of samples in conventional proteomics approach, presents a challenge to characterize S-glutathionylation of proteins. S-glutathionylation of proteins has been reported in medical conditions associated with high oxidative stress. In the present study, we attempted to characterize glutathionylation of CSF proteins in patients with multiple sclerosis which is associated with high oxidative stress. Using the nano-LC/ESI-MS platform, we adopted a modified proteomics approach and a targeted database search to investigate glutathionylation at the residue level of CSF proteins. Compared to patients with Intracranial hypertension, the following CSF proteins: Extracellular Superoxide dismutase (ECSOD) at Cys195, α1-antitrypsin (A1AT) at Cys232, Phospholipid transfer protein (PLTP) at Cys318, Alpha-2-HS-glycoprotein at Cys340, Ectonucleotide pyrophosphate (ENPP-2) at Cys773, Gelsolin at Cys304, Interleukin-18 (IL-18) at Cys38 and Ig heavy chain V III region POM at Cys22 were found to be glutathionylated in patients with multiple sclerosis during a relapse. ECSOD, A1AT, and PLTP were observed to be glutathionylated at the functionally important cysteine residues. In conclusion, in the present study using a modified proteomics approach we have identified and characterized glutathionylation of CSF proteins in patients with multiple sclerosis.

Targeting redox regulation to treat substance use disorder using N‐acetylcysteine

Substance use disorder (SUD) is a chronic relapsing disorder characterized by transitioning from acute drug reward to compulsive drug use. Despite the heavy personal and societal burden of SUDs, current treatments are limited and unsatisfactory. For this reason, a deeper understanding of the mechanisms underlying addiction is required. Altered redox status, primarily due to drug-induced increases in dopamine metabolism, is a unifying feature of abused substances. In recent years, knowledge of the effects of oxidative stress in the nervous system has evolved from strictly neurotoxic to include a more nuanced role in redox-sensitive signaling. More specifically, S-glutathionylation, a redox-sensitive post-translational modification, has been suggested to influence the response to drugs of abuse. In this review we will examine the evidence for redox-mediating drugs as therapeutic tools focusing on N-acetylcysteine as a treatment for cocaine addiction. We will conclude by suggesting future research directions that may further advance this field.

Exposure to ambient particulate matter induces oxidative stress in lung and aorta in a size- and time-dependent manner in rats

Exposure to particulate matter (PM) has been implicated in oxidative stress (OxS) and inflammation as underlying mechanisms of lung damage and cardiovascular alterations. PM is a chemical mixture that can be subdivided according to their aerodynamic size into coarse (CP), fine (FP), and ultrafine (UFP) particulates. We investigated, in a rat model, the induction of OxS (protein oxidation and antioxidant response), carcinogen-DNA adduct formation, and inflammatory mediators in lung in response to different airborne particulate fractions, CP, FP, and UFP, after an acute and subchronic exposure. In addition, OxS was evaluated in the aorta to assess the effects beyond the lungs. Exposure to CP, FP, and UFP induced time- and size-dependent lung protein oxidation and DNA adduct formation. After acute and subchronic exposure, nuclear factor erythroid-2 (Nrf2) activation was observed in the lung, by electrophoretic mobility shift assay, and the induction of mRNA antioxidant enzymes in the FP and UFP groups, but not in the CP. Cytokine concentration of interleukin 1β, interleukin 6, and macrophage inflammatory protein-2 was significantly increased in bronchoalveolar lavage fluid after acute exposure to FP and UFP. Activation of Nrf2 and expression of mRNA antioxidant enzymes were observed only after the subchronic exposure to FP and UFP in the aorta. Our results indicate that FP and UFP were mainly accountable for the oxidant toxic effects in the lung; OxS is spread from the lung to the cardiovascular system. We conclude that the biological mechanisms associated with transient OxS and inflammation are particle size and time-dependent exposure resulting in acute lung injury, which later reaches the vascular system.

Post-Translational Oxidative Modifications of Mitochondrial Complex I (NADH: Ubiquinone Oxidoreductase): Implications for Pathogenesis and Therapeutics in Human Diseases

Mitochondrial complex I (NADH: ubiquinone oxidoreductase; CI) is central to the electron transport chain (ETC), oxidative phosphorylation, and ATP production in eukaryotes. CI is a multi-subunit complex with a complicated yet organized structure that optimally connects electron transfer with proton translocation and forms higher-order supercomplexes with other ETC complexes. Efforts to understand the molecular genetics, expression profile of subunits, and structure-function relationship of CI have increased over the years due to the direct role of the complex in human diseases. Although mutations in the nuclear and mitochondrial genes of CI and altered expression of subunits could potentially lower CI activity leading to mitochondrial dysfunction in many diseases, oxidative post-translational modifications (PTMs) have emerged as an important mechanism contributing to altered CI activity. These mainly include reversible and irreversible cysteine modifications, tyrosine nitration, carbonylation, and tryptophan oxidation that are generated following exposure to reactive oxygen species/reactive nitrogen species. Interestingly, oxidative PTMs could contribute either to CI damage, mitochondrial dysfunction, and ensuing cell death or a response mechanism with potential cytoprotective effects. This has also emerged as a promising field for structural biologists since analysis of PTMs could assist in understanding the structure-function relationship of the complex and correlate electron transfer mechanism with energy production. However, analysis of PTMs of CI and their contribution to CI function are incomplete in many physiological and pathological conditions. This review aims to highlight the role of oxidative PTMs in modulating CI activity with implications toward pathobiology of CNS diseases and novel therapeutics.

Glycolysis promotes caspase-3 activation in lipid rafts in T cells

Resting T cells undergo a rapid metabolic shift to glycolysis upon activation in the presence of interleukin (IL)-2, in contrast to oxidative mitochondrial respiration with IL-15. Paralleling these different metabolic states are striking differences in susceptibility to restimulation-induced cell death (RICD); glycolytic effector T cells are highly sensitive to RICD, whereas non-glycolytic T cells are resistant. It is unclear whether the metabolic state of a T cell is linked to its susceptibility to RICD. Our findings reveal that IL-2-driven glycolysis promotes caspase-3 activity and increases sensitivity to RICD. Neither caspase-7, caspase-8, nor caspase-9 activity is affected by these metabolic differences. Inhibition of glycolysis with 2-deoxyglucose reduces caspase-3 activity as well as sensitivity to RICD. By contrast, IL-15-driven oxidative phosphorylation actively inhibits caspase-3 activity through its glutathionylation. We further observe active caspase-3 in the lipid rafts of glycolytic but not non-glycolytic T cells, suggesting a proximity-induced model of self-activation. Finally, we observe that effector T cells during influenza infection manifest higher levels of active caspase-3 than naive T cells. Collectively, our findings demonstrate that glycolysis drives caspase-3 activity and susceptibility to cell death in effector T cells independently of upstream caspases. Linking metabolism, caspase-3 activity, and cell death provides an intrinsic mechanism for T cells to limit the duration of effector function.

Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function

BACKGROUND/OBJECTIVES

Glutathione (GSH) is the most abundant endogenous antioxidant and a critical regulator of oxidative stress. Maintenance of optimal tissues for GSH levels may be an important strategy for the prevention of oxidative stress-related diseases. We investigated if oral administration of liposomal GSH is effective at enhancing GSH levels in vivo.

SUBJECTS/METHODS

A 1-month pilot clinical study of oral liposomal GSH administration at two doses (500 and 1000 mg of GSH per day) was conducted in healthy adults. GSH levels in whole blood, erythrocytes, plasma and peripheral blood mononuclear cells (PBMCs) were assessed in 12 subjects at the baseline and after 1, 2 and 4 weeks of GSH administration.

RESULTS

GSH levels were elevated after 1 week with maximum increases of 40% in whole blood, 25% in erythrocytes, 28% in plasma and 100% in PBMCs occurring after 2 weeks (P<0.05). GSH increases were accompanied by reductions in oxidative stress biomarkers, including decreases of 35% in plasma 8-isoprostane and 20% in oxidized:reduced GSH ratios (P<0.05). Enhancements in immune function markers were observed with liposomal GSH administration including Natural killer (NK) cell cytotoxicity, which was elevated by up to 400% by 2 weeks (P<0.05), and lymphocyte proliferation, which was elevated by up to 60% after 2 weeks (P<0.05). Overall, there were no differences observed between dose groups, but statistical power was limited due to the small sample size in this study.

CONCLUSIONS

Collectively, these preliminary findings support the effectiveness of daily liposomal GSH administration at elevating stores of GSH and impacting the immune function and levels of oxidative stress.

ROS and glutathionylation balance cytoskeletal dynamics in neutrophil extracellular trap formation

Neutrophils can release their genomic DNA as extracellular traps (NETs), which ensnare bacteria and limit their replication. Stojkov et al. find that modulation of cytoskeletal dynamics by reactive oxygen species and glutathionylation controls the degranulation and release of mitochondrial DNA required for NET formation.

The antimicrobial defense activity of neutrophils partly depends on their ability to form neutrophil extracellular traps (NETs), but the underlying mechanism controlling NET formation remains unclear. We demonstrate that inhibiting cytoskeletal dynamics with pharmacological agents or by genetic manipulation prevents the degranulation of neutrophils and mitochondrial DNA release required for NET formation. Wiskott-Aldrich syndrome protein–deficient neutrophils are unable to polymerize actin and exhibit a block in both degranulation and DNA release. Similarly, neutrophils with a genetic defect in NADPH oxidase fail to induce either actin and tubulin polymerization or NET formation on activation. Moreover, neutrophils deficient in glutaredoxin 1 (Grx1), an enzyme required for deglutathionylation of actin and tubulin, are unable to polymerize either cytoskeletal network and fail to degranulate or release DNA. Collectively, cytoskeletal dynamics are achieved as a balance between reactive oxygen species–regulated effects on polymerization and glutathionylation on the one hand and the Grx1-mediated deglutathionylation that is required for NET formation on the other.

Proteomic Analyses of Cysteine Redox in High-Fat-Fed and Fasted Mouse Livers: Implications for Liver Metabolic Homeostasis

Intensive oxidative stress occurs during high-fat-diet-induced hepatic fat deposition, suggesting a critical role for redox signaling in liver metabolism. Intriguingly, evidence shows that fasting could also result in redox-profile changes largely through reduced oxidant or increased antioxidant levels. However, a comprehensive landscape of redox-modified hepatic substrates is lacking, thereby hindering our understanding of liver metabolic homeostasis. We employed a proteomic approach combining iodoacetyl tandem mass tag and nanoliquid chromatography tandem mass spectrometry to quantitatively probe the effects of high-fat feeding and fasting on in vivo redox-based cysteine modifications. Compared with control groups, ∼60% of cysteine residues exhibited downregulated oxidation ratios by fasting, whereas ∼94% of these ratios were upregulated by high-fat feeding. Importantly, in fasted livers, proteins exhibiting diminished cysteine oxidation were annotated in pathways associated with fatty acid metabolism, carbohydrate metabolism, insulin, peroxisome proliferator-activated receptors, and oxidative respiratory chain signaling, suggesting that fasting-induced redox changes targeted major metabolic pathways and consequently resulted in hepatic lipid accumulation.

Protein CoAlation: a redox-regulated protein modification by coenzyme A in mammalian cells

Coenzyme A (CoA) is an obligatory cofactor in all branches of life. CoA and its derivatives are involved in major metabolic pathways, allosteric interactions and the regulation of gene expression. Abnormal biosynthesis and homeostasis of CoA and its derivatives have been associated with various human pathologies, including cancer, diabetes and neurodegeneration. Using an anti-CoA monoclonal antibody and mass spectrometry, we identified a wide range of cellular proteins which are modified by covalent attachment of CoA to cysteine thiols (CoAlation). We show that protein CoAlation is a reversible post-translational modification that is induced in mammalian cells and tissues by oxidising agents and metabolic stress. Many key cellular enzymes were found to be CoAlated in vitro and in vivo in ways that modified their activities. Our study reveals that protein CoAlation is a widespread post-translational modification which may play an important role in redox regulation under physiological and pathophysiological conditions.

Mushrooms: A rich source of the antioxidants ergothioneine and glutathione

While mushrooms are the highest dietary source for the unique sulfur-containing antioxidant ergothioneine, little is known regarding levels of the major biological antioxidant glutathione. Thus, our objectives were to determine and compare levels of glutathione, as well as ergothioneine, in different species of mushrooms. Glutathione levels varied >20-fold (0.11-2.41mg/gdw) with some varieties having higher levels than reported for other foods. Ergothioneine levels also varied widely (0.15-7.27mg/gdw) and were highly correlated with those of glutathione (r=0.62, P<0.001). Both antioxidants were more concentrated in pileus than stipe tissues in selected mushrooms species. Agaricus bisporus harvested during the third cropping flush contained higher levels of ergothioneine and glutathione compared to the first flush, possibly as a response to increased oxidative stress. This study demonstrated that certain mushroom species are high in glutathione and ergothioneine and should be considered an excellent dietary source of these important antioxidants.

Mechanism of ROS scavenging and antioxidant signalling by redox metallic and fullerene nanomaterials: Potential implications in ROS associated degenerative disorders

BACKGROUND

The balance between oxidation and anti-oxidation is believed to be critical in maintaining healthy biological systems. However, our endogenous antioxidant defense systems are incomplete without exogenous antioxidants and, therefore, there is a continuous demand for exogenous antioxidants to prevent stress and ageing associated disorders. Nanotechnology has yielded enormous variety of nanomaterials (NMs) of which metallic and carbonic (mainly fullerenes) NMs, with redox property, have been found to be strong scavengers of ROS and antioxidants in preclinical in vitro and in vivo models.

SCOPE OF REVIEW

Redox activity of metal based NMs and membrane translocation time of fullerene NMs seem to be the major determinants in ROS scavenging potential exhibited by these NMs. A comprehensive knowledge about the effects of ROS scavenging NMs in cellular antioxidant signalling is largely lacking. This review compiles the mechanisms of ROS scavenging as well as antioxidant signalling of the aforementioned metallic and fullerene NMs.

MAJOR CONCLUSIONS

Direct interaction between NMs and proteins does greatly affect the corona/adsorption formation dynamics but such interaction does not provide the explanation behind diverse biological outcomes induced by NMs. Indirect interaction, however, that could occur via NMs uptake and dissolution, NMs ROS induction and ROS scavenging property, and NMs membrane translocation time seem to work as a central mode of interaction.

GENERAL SIGNIFICANCE

The usage of potential antioxidant NMs in biological systems would greatly impact the field of nanomedicine. ROS scavenging NMs hold great promise in the future treatment of ROS related degenerative disorders.

Glutaredoxins concomitant with optimal ROS activate AMPK through S-glutathionylation to improve glucose metabolism in type 2 diabetes

AMPK dysregulation contributes to the onset and development of type 2 diabetes (T2DM). AMPK is known to be activated by reactive oxygen species (ROS) and antioxidant interference. However the mechanism by which redox state mediates such contradictory result remains largely unknown. Here we used streptozotocin-high fat diet （STZ-HFD） induced-type 2 diabetic rats and cells lines (L02 and HEK 293) to explore the mechanism of redox-mediated AMPK activation. We show glutaredoxins (Grxs) concomitant with optimal ROS act as an essential mediator for AMPK activation. ROS level results in different mechanisms for AMPK activation. Under low ROS microenvironment, Grxs-mediated S-glutathionylation on AMPK-α catalytic subunit activates AMPK to improve glucose transportation and degradation while inhibiting glycogen synthesis and keeping redox balance. While, under high ROS microenvironment, AMPK is activated by an AMP-dependent mechanism, however sustained high level ROS also causes loss of AMPK protein. This finding provides evidence for a new approach to diabetes treatment by individual doses of ROS or antioxidant calibrated against the actual redox level in vivo. Moreover, the novel function of Grxs in promoting glucose metabolism may provide new target for T2DM treatment.