Peroxiredoxins: guardians against oxidative stress and modulators of peroxide signaling

Peroxiredoxin 6 (Prx6) of Penaeus vannamei and effect of phenanthrene on Prx6 and glutathione peroxidase 4 expression, glutathione-dependent peroxidase activity and lipid peroxidation

Polycyclic aromatic hydrocarbons (PAHs), such as phenanthrene (PHE), are common pollutants found in coastal areas where shrimp farming is developed. Even though PAHs can have adverse effects on physiology, shrimp can detoxify and metabolize toxic compounds and neutralize the reactive oxygen species (ROS) produced during this process. This requires the activation of multiple antioxidant enzymes, including peroxiredoxin 6 (Prx6). Prx6 uses glutathione (GSH) to reduce phospholipid hydroperoxides, a function shared with GSH peroxidase 4 (GPx4). Prx6 has been scarcely studied in crustaceans exposed to pollutants. Herein, we report a novel Prx6 from the shrimp Penaeus vannamei that is abundantly expressed in gills and hepatopancreas. To elucidate the involvement of Prx6 in response to PAHs, we analyzed its expression in the hepatopancreas of shrimp sub-lethally exposed to PHE (3.3 μg/L) and acetone (control) for 24, 48, 72, and 96 h, along with GPx4 expression, GSH-dependent peroxidase activity, and lipid peroxidation (indicated by TBARS). We found that GPx4 expression is not affected by PHE, but Prx6 expression and peroxidase activity decreased during the trial. This might contribute to the rise of TBARS found at 48 h of exposure. However, maintaining GPx4 expression could aid to minimize lipid damage during longer periods of exposure to PHE.

Improvement of succinate production from methane by combining rational engineering and laboratory evolution in Methylomonas sp. DH-1

Recently, methane has been considered a next-generation carbon feedstock due to its abundance and it is main component of shale gas and biogas. Methylomonas sp. DH-1 has been evaluated as a promising industrial bio-catalyst candidate. Succinate is considered one of the top building block chemicals in the agricultural, food, and pharmaceutical industries. In this study, succinate production by Methylomonas sp. DH-1 was improved by combining adaptive laboratory evolution (ALE) technology with genetic engineering in the chromosome of Methylomonas sp. DH-1, such as deletion of bypass pathway genes (succinate dehydrogenase and succinate semialdehyde dehydrogenase) or overexpression of genes related with succinate production (citrate synthase, pyruvate carboxylase and phosphoenolpyruvate carboxylase). Through ALE, the maximum consumption rate of substrate gases (methane and oxygen) and the duration maintaining high substrate gas consumption rates was enhanced compared to those of the parental strain. Based on the improved methane consumption, cell growth (OD600) increased more than twice, and the succinate titer increased by ~ 48% from 218 to 323 mg/L. To prevent unwanted succinate consumption, the succinate semialdehyde dehydrogenase gene was deleted from the genome. The first enzyme of TCA cycle (citrate synthase) was overexpressed. Pyruvate carboxylase and phosphoenolpyruvate carboxylase, which produce oxaloacetate, a substrate for citrate synthase, were also overproduced by a newly identified strong promoter. The new strong promoter was screened from RNA sequencing data. When these modifications were combined in one strain, the maximum titer (702 mg/L) was successfully improved by more than three times. This study demonstrates that successful enhancement of succinic acid production can be achieved in methanotrophs through additional genetic engineering following adaptive laboratory evolution.

Role of MTH1 in oxidative stress and therapeutic targeting of cancer

Cancer cells maintain high levels of reactive oxygen species (ROS) to drive their growth, but ROS can trigger cell death through oxidative stress and DNA damage. To survive enhanced ROS levels, cancer cells activate their antioxidant defenses. One such defense is MTH1, an enzyme that prevents the incorporation of oxidized nucleotides into DNA, thus preventing DNA damage and allowing cancer to proliferate. MTH1 levels are often elevated in many cancers, and thus, inhibiting MTH1 is an attractive strategy for suppressing tumor growth and metastasis. Targeted MTH1 inhibition can induce DNA damage in cancer cells, exploiting their vulnerability to oxidative stress and selectively targeting them for destruction. Targeting MTH1 is promising for cancer treatment because normal cells have lower ROS levels and are less dependent on these pathways, making the approach both effective and specific to cancer. This review aims to investigate the potential of MTH1 as a therapeutic target, especially in cancer treatment, offering detailed insights into its structure, function, and role in disease progression. We also discussed various MTH1 inhibitors that have been developed to selectively induce oxidative damage in cancer cells, though their effectiveness varies. In addition, this review provide deeper mechanistic insights into the role of MTH1 in cancer prevention and oxidative stress management in various diseases.

PDE9A Inhibition Improves Coronary Microvascular Rarefaction and Left Ventricular Diastolic Dysfunction in the ZSF1 Rat Model of HFpEF

OBJECTIVE

Heart failure with preserved ejection fraction (HFpEF) commonly arises from comorbid diseases, such as hypertension, obesity, and diabetes mellitus. Selective inhibition of phosphodiesterase 9A (PDE9A) has emerged as a potential therapeutic approach for treating cardiometabolic diseases. Coronary microvascular disease (CMD) is one of the key mechanisms contributing to the development of left ventricular (LV) diastolic dysfunction in HFpEF. Our study aimed to investigate the mechanisms by which PDE9A inhibition could ameliorate CMD and improve LV diastolic function in HFpEF.

METHODS AND RESULTS

The obese diabetic Zucker fatty/spontaneously hypertensive heart failure F1 hybrid (ZSF1) rat model of HFpEF was employed in which it was found that a progressively developing coronary microvascular rarefaction is associated with LV diastolic dysfunction when compared to lean, nondiabetic hypertensive controls. Obese ZSF1 rats had an increased cardiac expression of PDE9A. Treatment of obese ZSF1 rats with the selective PDE9A inhibitor, PF04447943 (3 mg/kg/day, oral gavage for 2 weeks), improved coronary microvascular rarefaction and LV diastolic dysfunction, which was accompanied by reduced levels of oxidative and nitrosative stress markers, hydrogen peroxide, and 3-nitrotyrosine. Liquid chromatography-mass spectrometry (LC-MS) proteomic analysis identified peroxiredoxins (PRDX) as downregulated antioxidants in the heart of obese ZSF1 rats, whereas Western immunoblots showed that the protein level of PRDX5 was significantly increased by the PF04447943 treatment.

CONCLUSIONS

Thus, in the ZSF1 rat model of human HFpEF, PDE9A inhibition improves coronary vascular rarefaction and LV diastolic dysfunction, demonstrating the usefulness of PDE9A inhibitors in ameliorating CMD and LV diastolic dysfunction through augmenting PRDX-dependent antioxidant mechanisms.

Chitosan biomineralized with ions-doped nano-hydroxyapatite tunes osteoblasts metabolism and DNA damage

Hydroxyapatite (HA) is a bioceramic material widely used as a bone biomimetic substitute and can be synthesized by biomineralization, according to which HA nanoparticles are formed on a polymer template. Nevertheless, little is known about the effect of ion doping and biomineralization on cell metabolism, oxidative stress, and DNA damage. In the present contribution, we report on synthesizing and characterizing biomineralized chitosan as a polymer template with HA nanoparticles doped with magnesium (MgHA) and iron ions (FeHA). The physical-chemical and morphological characterization confirmed the successful synthesis of low crystalline ions-doped HA nanoparticles on the chitosan template, whereas the biochemical activity of the resulting nanoparticles towards human osteoblasts-like cells (MG63 and HOBIT) was investigated considering their effect on cell metabolism, proliferation, colony formation, redox status, and DNA damage extent. Data obtained suggest that particles enhance cell metabolism but partially limit cell proliferation. The redox status of cells was measured suggesting a slight increase in Reactive Oxygen Species production with chitosan biomineralized with iron-doped HA, whereas no effect with magnesium-doped HA and no effect of all formulations on the oxidation level of Peroxiredoxin. On the other hand, DNA damage was investigated by COMET assay, and expression and foci γH2AX. These latter tests indicated that HA-based nanoparticles promote DNA damage which is enhanced by chitosan thus suggesting that chitosan favors the nanoparticles' internalization by cells and modulates their biological activity. The potential DNA damage should be considered - and potentially exploited for instance in anticancer treatment - when HA-based particles are used to devise biomaterials.

Characterization of thioredoxin-thioredoxin reductase system in Filifactor alocis

INTRODUCTION

Filifactor alocis is a newly appreciated member of the periodontal community with a strong periodontal disease correlation. Little is known about the survival mechanisms by which F. alocis copes with oxidative stress and establishes the infection within the local inflammatory microenvironment of the periodontal pocket. The aim of this study is to investigate if F. alocis putative peroxiredoxin/AhpC protein FA768 may constitute an alkyl hydroperoxide reductase system utilizing putative thioredoxin reductase protein FA608, and putative thioredoxin/glutaredoxin homolog FA1411/FA455.

METHODS

FA768, FA608, FA1411 and FA455 proteins from F. alocis were expressed and purified from Escherichia coli. Insulin and 5,5-dithio-bis-2-nitrobenzoic acid (DTNB) reduction assays were performed to determine if purified FA1411 and FA455 proteins could be a substrate for FA608. The peroxidase activity of FA768 was examined by measuring its ability to reduce hydrogen peroxide (H2O2) with FA608 and FA1411/FA455 provided as the reducing systems. Further, the hydroperoxide substrate specificity of FA768 was analyzed by monitoring the NADPH oxidation in the presence of different peroxides, including H2O2, cumyl hydroperoxide (CHP), and tert-butyl hydroperoxide (t-BHP).

RESULTS

In this study, we have demonstrated the existence of a functioning thioredoxin-dependent alkyl hydroperoxide system in F. alocis. This system is comprised of a thioredoxin reductase (FA608), a thioredoxin/glutaredoxin homolog (FA1411/FA455), and a typical 2-cysteine peroxiredoxin/AhpC (FA768). FA608, together with FA1411/FA455, can function as a thioredoxin reductase system to reduce insulin, DTNB, and FA768. FA455 is a glutaredoxin-like protein with thioredoxin functions in F. alocis. Both the FA768/FA608/FA1411 and FA768/FA608/FA455 reductase systems were NADPH-dependent and exhibited specificity for broad hydroperoxide substrates H2O2, CHP, and t-BHP.

CONCLUSIONS

This is the first study of a thioredoxin dependent alkyl hydroperoxide system from a periodontal pathogen. This system is proposed to protect F. alocis against oxidative stress due to the likely absence of a catalase or an additional peroxiredoxin homolog.

Effect of peroxiredoxin 1 or peroxiredoxin 2 knockout on the thiol proteome of Jurkat cells

Peroxiredoxins are important regulators of cellular peroxide metabolism. As antioxidants, they restrict oxidation of other cell proteins, but as signaling molecules they can act as sensors and promote thiol protein oxidation via a redox relay mechanism. The presence of peroxiredoxins could therefore influence other thiol proteins, even in cells experiencing endogenous redox activity. To investigate this for the two cytoplasmic peroxiredoxins, Prdx1 and Prdx2, we have compared the thiol proteome of wildtype Jurkat cells with cells in which either one was knocked out. Using mass spectrometry and isotope tagging, approximately 10,000 common CysSH-containing peptides were detected for each WT/KO comparison. Knockout of Prdx1 or Prdx2 resulted in a change in redox state of a small selection of Cys residues, with less than 100 giving more than a 2-fold difference. Strikingly, a large proportion of these, including those that showed the greatest change, were common to both KOs. Some Cys residues showed more oxidation in the knockouts, whereas others showed less. The candidate proteins have diverse functions and have not been known to be oxidant sensitive. No differences were seen in redox state of Cys residues of other Prdxs and oxidant sensitive proteins. A change in expression in Prdx2 knockout cells was indicated for seven cytoskeletal or regulatory thiol proteins, three of which were tested and validated by western blotting. Little firm evidence was found for thiol redox changes dependent on either Prdx that could be attributed to oxidation via a relay mechanism.

Vitamin C in the Management of Thyroid Cancer: A Highway to New Treatment?

Thyroid cancer (TC) is the most common endocrine malignancy, with an increased global incidence in recent decades, despite a substantially unchanged survival. While TC has an excellent overall prognosis, some types of TC are associated with worse patient outcomes, depending on the genetic setting. Furthermore, oxidative stress is related to more aggressive features of TC. Vitamin C, an essential nutrient provided with food or as a dietary supplement, is a well-known antioxidant and a scavenger of reactive oxygen species; however, at high doses, it can induce pro-oxidant effects, acting through multiple biological mechanisms that play a crucial role in killing cancer cells. Although experimental data and, less consistently, clinical studies, suggest the possibility of antineoplastic effects of vitamin C at pharmacological doses, the antitumor efficacy of this nutrient in TC remains at least partly unexplored. Therefore, this review discusses the current state of knowledge on the role of vitamin C, alone or in combination with other conventional therapies, in the management of TC, the mechanisms underlying this association, and the perspectives that may emerge in TC treatment strategies, and, also, in light of the development of novel functional foods useful to this extent, by implementing novel sensory analysis strategies.

Loss of function in protein Z (PROZ) is associated with increased risk of ischemic stroke in the UK Biobank

BACKGROUND

The vitamin K-dependent coagulation factor protein Z (PZ), encoded by the PROZ gene, is canonically considered to have anticoagulant effects through negative regulation of factor Xa. Paradoxically, higher circulating PZ concentrations have repeatedly been associated with an elevated risk of acute ischemic stroke.

OBJECTIVES

We performed a large-scale genetic association study to examine the relationship between germline genetic variants in PROZ and the risk of ischemic stroke.

METHODS

Using whole-exome sequencing and clinical data for 416 711 participants in the UK Biobank (UKB), we identified individuals with rare (minor allele frequency ≤0.1%) putatively function-altering variants in PROZ. Using Firth's logistic regression and controlling for known stroke risk factors, we evaluated the association between variant carrier status and noncardioembolic ischemic stroke (NCEIS). Additionally, we evaluated differences in the plasma levels of 1472 proteins between PROZ variant carriers and noncarriers in a subset of 48 893 UKB participants.

RESULTS

After accounting for missing data, qualifying variants in PROZ were identified in 414 UKB participants (99.0% heterozygous). Variant carriers had a significantly increased risk of NCEIS (odds ratio, 2.34; 95% CI, 1.15-4.13; P = .02) but not of venous thromboembolism, myocardial infarction, or peripheral artery disease. Plasma proteomics analysis revealed that PROZ variant carriers had significantly elevated levels of 2 proteins related to the response to cerebral ischemia, peroxiredoxins 1 and 6 (PRDX1: fold change, 1.83; P = 1.3 × 10-5; PRDX6: fold change, 1.78; P = 9.6 × 10-10).

CONCLUSION

Lifelong exposure to decreased PZ levels confers a significantly increased risk of NCEIS, consistent with the role of PZ as an anticoagulant factor.

Prebiotic stachyose inhibits PRDX5 activity and castration-resistant prostate cancer development

Stachyose (STA) is a prebiotic with poor oral bioavailability. In this study, we developed stachyose caproate (C6-STA), as a novel STA derivative, to demonstrate its high adsorption rate via oral administration. Pharmacokinetic analysis reveals that after absorption, the STA derived from C6-STA reaches its highest peak in the blood, liver, and kidney at 20 min, 30 min, and 12-24 h, with approximate levels of 1200 μg/mL, 0.14 μg/mL, and 0.2-0.3 μg/mL, respectively. In addition, the accumulation of STA in prostate tissues of mice with castration-resistant prostate cancer (CRPC) (1.75 μg/mg) is 10-fold higher than that in normal prostate tissues (0.14 μg/mg). The analysis also reveals that C6-STA has t1/2 of 12.8 h and Tmax of 0.25 h, indicating that it has the potential to be used as a promising drug in clinical practice. The toxicological evaluation shows no obvious side effects of C6-STA in mice administered with a 0.2 g/kg intragastric dose. Pharmacodynamic analysis and mechanism investigation of C6-STA show its ability to inhibit peroxiredoxin 5 (PRDX5) enzyme activity, disrupt PRDX5-nuclear factor erythroid 2-related factor 2 (NRF2) interaction, and decrease NAD(P)H quinone dehydrogenase 1 (NQO1) levels. NQO1 decrease further causes the accumulation of quinone radicals, which ultimately leads to the apoptosis of LNCaP cell-derived drug-tolerant persister (DTP) cells and slows CRPC progression. Our study discovered the anti-tumor activity of stachyose and shows that prebiotics have biological functions in vivo besides in the gut. Further investigation of C6-STA, especially in CRPC patients, is warranted.

Treatment of Acute and Long-COVID, Diabetes, Myocardial Infarction, and Alzheimer's Disease: The Potential Role of a Novel Nano-Compound-The Transdermal Glutathione-Cyclodextrin Complex

Oxidative stress (OS) occurs from excessive reactive oxygen species or a deficiency of antioxidants-primarily endogenous glutathione (GSH). There are many illnesses, from acute and post-COVID-19, diabetes, myocardial infarction to Alzheimer's disease, that are associated with OS. These dissimilar illnesses are, in order, viral infections, metabolic disorders, ischemic events, and neurodegenerative disorders. Evidence is presented that in many illnesses, (1) OS is an early initiator and significant promotor of their progressive pathophysiologic processes, (2) early reduction of OS may prevent later serious and irreversible complications, (3) GSH deficiency is associated with OS, (4) GSH can likely reduce OS and restore adaptive physiology, (5) effective administration of GSH can be accomplished with a novel nano-product, the GSH/cyclodextrin (GC) complex. OS is an overlooked pathological process of many illnesses. Significantly, with the GSH/cyclodextrin (GC) complex, therapeutic administration of GSH is now available to reduce OS. Finally, rigorous prospective studies are needed to confirm the efficacy of this therapeutic approach.

Antioxidant enzyme Prdx1 inhibits osteoclastogenesis via suppressing ROS and NFATc1 signaling pathways

Bone is a dynamic organ which continuously undergoes remodeling throughout one's lifetime. Cellular production of reactive oxygen species (ROS) is essential for regulating bone homeostasis. Osteoclasts, multinucleated giant cells differentiated from macrophage lineage, are responsible for osteolytic bone conditions which are closely linked to ROS signaling pathways. In this study, an anti-ROS enzyme, peroxiredoxin 1 (Prdx1) was found to be expressed both in bone marrow macrophages and osteoclasts. Recombinant Prdx1 protein was found to dose-dependently inhibit ROS production and osteoclast differentiation. Mechanistically, Prdx1 protein also attenuated NFATc1 activation as well as the expression of C-Fos, V-ATPase-d2, Cathepsin K, and Integrin αV. Collectively, Prdx1 is a negative regulator on osteoclast formation via inhibiting RANKL-mediated ROS activity, thus suggesting its potential application for treating osteoclast related disorders.

Sex-dependent regulation of retinal pigment epithelium and retinal function by Pgc-1α

Age-related macular degeneration (AMD) is a major cause of blindness that affects people over 60. While aging is the prominent factor in AMD, studies have reported a higher prevalence of AMD in women compared to age-matched men. Higher levels of the innate immune response's effector proteins complement factor B and factor I were also found in females compared to males in intermediate AMD. However, the mechanisms underlying these differences remain elusive. Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) is a key regulator of mitochondrial biogenesis and metabolic pathways. Previously, we showed that Pgc-1α repression and high-fat diet induce drastic AMD-like phenotypes in mice. Our recent data revealed that Pgc-1α repression alone can also induce retinal pigment epithelium (RPE) and retinal dysfunction in mice, and its inhibition in vitro results in lipid droplet accumulation in human RPE. Whether sex is a contributing factor in these phenotypes remains to be elucidated. Using electroretinography, we demonstrate that sex could influence RPE function during aging independent of Pgc-1α in wild-type (WT) mice. We further show that Pgc-1α repression exacerbates RPE and retinal dysfunction in females compared to aged-match male mice. Gene expression analyses revealed that Pgc-1α differentially regulates genes related to antioxidant enzymes and mitochondrial dynamics in males and females. RPE flat mounts immunolabeled with TOMM20 and DRP1 indicated a sex-dependent role for Pgc-1α in regulating mitochondrial fission. Analyses of mitochondrial network morphology suggested sex-dependent effects of Pgc-1α repression on mitochondrial dynamics. Together, our study demonstrates that inhibition of Pgc-1α induces a sex-dependent decline in RPE and retinal function in mice. These observations on the sex-dependent regulation of RPE and retinal function could offer novel insights into targeted therapeutic approaches for age-related RPE and retinal degeneration.

Cellular oxidants and the proteostasis network: balance between activation and destruction

Loss of protein homeostasis (proteostasis) is a common hallmark of aging and age-associated diseases. Considered as the guardian of proteostasis, the proteostasis network (PN) acts to preserve the functionality of proteins during their lifetime. However, its activity declines with age, leading to disease manifestation. While reactive oxygen species (ROS) were traditionally considered culprits in this process, recent research challenges this view. While harmful at high concentrations, moderate ROS levels protect the cell against age-mediated onset of proteotoxicity by activating molecular chaperones, stress response pathways, and autophagy. This review explores the nuanced roles of ROS in proteostasis and discusses the most recent findings regarding the redox regulation of the PN and its potential in extending healthspan and delaying age-related pathologies.

HPLC with chiral stationary phase for separation and kinetics study of aspartic acid epimerization in Peroxiredoxin 2 active site peptide

Amino acid epimerization, a process of converting L-amino acids to D-amino acids, will lead to modification in the protein structure and, subsequently, its biological function. This modification causes no change in protein m/z and may be overlooked during protein analysis. Aspartic Acid Epimerization (AAE) is faster than other amino acids and could be accelerated by free radicals and peroxides. In this work, a novel and site-specific HPLC method using a chiral stationary phase for determining the AAE in the active site model peptide (AP) of Peroxiredoxin 2 has been developed and validated. The developed method showed good linearity (1 - 200 μg/mL) and recoveries of the limit of quantification (LOQ), low, medium, and high concentrations were between 85% and 115%. The Kinetics of AAE in AP were studied using the developed method, and the results showed that when ascorbic acid and Cu2+ coexisted, the AP epimerized rapidly. The AAE extent increased with time and was positively correlated with hydrogen peroxide generation.

Characterization of a Novel Oxidative Stress Responsive Transcription Regulator in Mycobacterium bovis

The antioxidant defense is critical for the survival of intracellular pathogens such as Mycobacterium tuberculosis complex (MTBC) species, including Mycobacterium bovis, which are often exposed to an oxidative environment caused by reactive oxygen species (ROS) in hosts. However, the signaling pathway in mycobacteria for sensing and responding to oxidative stress remains largely unclear. In this study, we characterize a TetR-type transcription regulator BCG_3893c, designated AotM, as a novel redox sensor in Mycobacterium bovis that increases mycobacterial tolerance to oxidative stress. AotM is required for the growth of M. bovis in the presence of 1 mM hydrogen peroxide. Loss of the aotM gene leads to altered transcriptional profiles with 352 genes significantly up-regulated and 25 genes significantly down-regulated. AotM recognizes a 14-bp palindrome sequence motif and negatively regulates the expression of a FAD-dependent oxidoreductase encoded by bcg_3892c. Overexpression of BCG_3892c increases intracellular ROS production and reduces the growth of M. bovis. In summary, we propose that AotM enhances the mycobacterial resistance against oxidative stress probably by inhibiting intracellular ROS production. Our findings reveal a novel underlying regulatory mechanism behind mycobacterial oxidative stress adaptation.

Is oxidative stress - antioxidants imbalance the physiopathogenic core in pediatric obesity?

Despite the early recognition of obesity as an epidemic with global implications, research on its pathogenesis and therapeutic approach is still on the rise. The literature of the 21st century records an excess weight found in up to 1/3 of children. Both the determining factors and its systemic effects are multiple and variable. Regarding its involvement in the potentiation of cardio-vascular, pulmonary, digestive, metabolic, neuro-psychic or even dermatological diseases, the information is already broadly outlined. The connection between the underlying disease and the associated comorbidities seems to be partially attributable to oxidative stress. In addition to these, and in the light of the recent COVID-19 pandemic, the role played by oxidative stress in the induction, maintenance and potentiation of chronic inflammation among overweight children and adolescents becomes a topic of interest again. Thus, this review's purpose is to update general data on obesity, with an emphasis on the physiopathological mechanisms that underlie it and involve oxidative stress. At the same time, we briefly present the latest principles of pathology diagnosis and management. Among these, we will mainly emphasize the impact played by endogenous and exogenous antioxidants in the evolutionary course of pediatric obesity. In order to achieve our objectives, we will refer to the most recent studies published in the specialized literature.

Mitochondria in Retinal Ganglion Cells: Unraveling the Metabolic Nexus and Oxidative Stress

This review explored the role of mitochondria in retinal ganglion cells (RGCs), which are essential for visual processing. Mitochondrial dysfunction is a key factor in the pathogenesis of various vision-related disorders, including glaucoma, hereditary optic neuropathy, and age-related macular degeneration. This review highlighted the critical role of mitochondria in RGCs, which provide metabolic support, regulate cellular health, and respond to cellular stress while also producing reactive oxygen species (ROS) that can damage cellular components. Maintaining mitochondrial function is essential for meeting RGCs' high metabolic demands and ensuring redox homeostasis, which is crucial for their proper function and visual health. Oxidative stress, exacerbated by factors like elevated intraocular pressure and environmental factors, contributes to diseases such as glaucoma and age-related vision loss by triggering cellular damage pathways. Strategies targeting mitochondrial function or bolstering antioxidant defenses include mitochondrial-based therapies, gene therapies, and mitochondrial transplantation. These advances can offer potential strategies for addressing mitochondrial dysfunction in the retina, with implications that extend beyond ocular diseases.

Unraveling the Peroxidase Activity in Peroxiredoxins: A Comprehensive Review of Mechanisms, Functions, and Biological Significance

Peroxiredoxins (Prxs) are members of the antioxidant enzymes necessary for every living object in the three domains of life and play critical roles in controlling peroxide levels in cells. This comprehensive literature review aims to elucidate the peroxidase activity of Prxs, examining their roles and significance for organisms across various taxa. Ironically, the primary role of the Prxs is the peroxidase activity, which comprises the reduction of hydrogen peroxide and other organic hydroperoxides and decreases the risk of oxidative damage in the cells. The above enzymatic activity occurs through the reversible oxidation-reduction catalyzed by cysteine residues in the active site by forming sulfenic acid and reduction by intracellular reductants. Structurally and functionally, Prxs function as dimers or decamers and show different catalytic patterns according to their subfamilies or cellular compartments. Compared to the mechanisms of the other two subgroups of Prxs, including 2-Cys Prxs and atypical Prxs, the 1-Cys Prxs have monomer-dimer switch folding coupled with catalytic activity. In addition to their peroxidase activity, which is widely known, Prxs are becoming acknowledged to be involved in other signaling processes, including redox signaling and apoptosis. This aversion to oxidative stress and regulation by the cellular redox state places them at the heart of adaptive cellular responses to changes in the environment or manifestations of diseases. In conclusion, based on the data obtained and on furthering the knowledge of Prxs' structure and function, these enzymes may be classified as a diverse yet essential family of proteins that can effectively protect cells from the adverse effects of oxidative stress due to peroxidase activity. This indicates secondary interactions, summarized as peroxide detoxification or regulatory signaling, and identifies their applicability in multiple biological pathways. Such knowledge is valuable for enhancing the general comprehension of essential cellular functions and disclosing further therapeutic approaches to the diseases caused by the increased production of reactive oxygen species.

Short-term dietary teprenone improved thermal tolerance and mitigated liver damage caused by heat stress in juvenile largemouth bass (Micropterus salmoides)

Heat stress seriously threatens fish survival and health, demanding immediate attention. Teprenone is a gastric mucosal protective agent that can induce heat shock protein expression. This research investigated the effects of teprenone on largemouth bass (Micropterus salmoides) subjected to heat stress. Juvenile fish were assigned to different groups: group C (control group, 0 mg teprenone/kg diet), T0, T200, T400, and T800 (0, 200, 400, and 800 mg teprenone/kg diet, respectively), which were fed for 3 days, followed by a day without the diet. All groups except group C were subjected to acute heat stress (from 24 °C to 35 °C at 1 °C per hour and then maintained at 35 °C for 3 h). The results were as follows: The critical thermal maxima were significantly higher in the T200, T400, and T800 groups compared with the T0 group (P < 0.05). Heat stress caused severe damage to the tissue morphology of the liver, while teprenone significantly reduced this injury (P < 0.05). Serum cortisol concentration decreased gradually as teprenone concentration increased, and the lowest concentration was observed in the T800 group (P < 0.05). Compared with the T0 group, the serum activities of aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase were significantly lower in the T200, T400, and T800 groups (P < 0.05). The liver activities of catalase, total superoxide dismutase, and peroxidase were significantly higher in the T200 group than in the T0 group (P < 0.05). Transcript levels of the heat shock proteins (hsp90, hsp70, hspa5, and hsf1) and caspase family (caspase3 and caspase9) in the liver of the T200 group were significantly higher than those of the T0 group (P < 0.05). Western blot results showed that HSP70 and HSPA5 in the liver were significantly upregulated in the T200 group compared with the T0 group (P < 0.05). In summary, dietary teprenone improved thermal tolerance, alleviated heat stress damage in the liver, enhanced antioxidant capacity, and upregulated heat shock proteins in juvenile largemouth bass. This study offers theoretical support for applying teprenone in aquaculture to reduce financial losses caused by abiotic factors.

How are hydrogen peroxide messages relayed to affect cell signalling?

H2O2 signals trigger adaptive responses affecting cell division, differentiation, migration, and survival. These signals are transduced by selective oxidation of cysteines on specific target proteins, with redox-sensitive cysteines now identified in many proteins, including both kinases and phosphatases. Assessing the contribution of these oxidation events to cell signalling presents several challenges including understanding how and when the selective oxidation of specific proteins takes place in vivo. In recent years, a combination of biochemical, structural, genetic, and computational approaches in fungi, plants, and animals have revealed different ways in which thiol peroxidases (peroxiredoxins) are bypassed or utilised in relaying these signals. Together, these mechanisms provide a conceptual framework for selectively oxidising proteins that will further advance understanding of how redox modifications contribute to health and disease.

PRDX6 augments selenium utilization to limit iron toxicity and ferroptosis

Ferroptosis is a form of regulated cell death induced by iron-dependent accumulation of lipid hydroperoxides. Selenoprotein glutathione peroxidase 4 (GPX4) suppresses ferroptosis by detoxifying lipid hydroperoxides via a catalytic selenocysteine (Sec) residue. Sec, the genetically encoded 21st amino acid, is biosynthesized from a reactive selenium donor on its cognate tRNA[Ser]Sec. It is thought that intracellular selenium must be delivered 'safely' and 'efficiently' by a carrier protein owing to its high reactivity and very low concentrations. Here, we identified peroxiredoxin 6 (PRDX6) as a novel selenoprotein synthesis factor. Loss of PRDX6 decreases the expression of selenoproteins and induces ferroptosis via a reduction in GPX4. Mechanistically, PRDX6 increases the efficiency of intracellular selenium utilization by transferring selenium between proteins within the selenocysteyl-tRNA[Ser]Sec synthesis machinery, leading to efficient synthesis of selenocysteyl-tRNA[Ser]Sec. These findings highlight previously unidentified selenium metabolic systems and provide new insights into ferroptosis.

Molecular variations to the proteome of zebrafish larvae induced by environmentally relevant copper concentrations

Contaminants are increasingly accumulating in aquatic environments and biota, with potential adverse effects on individual organisms, communities and ecosystems. However, studies that explore the molecular changes in fish caused by environmentally relevant concentrations of metals, such as copper (Cu), are limited. This study uses embryos of the model organism zebrafish (Danio rerio) to investigate effect of Cu on the proteome and amino acid (AA) composition of fish. Wild-type embryos at 24 h post-fertilisation were exposed to Cu (2 µg L-1 to 120 µg L-1) for 96 h and the number of healthy larvae were determined based on larvae that had hatched and did not display loss of equilibrium (LOE). The effect concentrations where Cu caused a 10 % (EC10) or 50 % (EC50) decrease in the number of healthy larvae were calculated as 3.7 µg L-1 and 10.9 µg L-1, respectively. Proteomics analysis of embryos exposed to the EC10 and EC50 concentrations of Cu revealed the proteome to differ more strongly after 48 h than 96 h, suggesting the acclimatisation of some larvae. Exposure to excess Cu caused differentially expressed proteins (DEPs) involved in oxidative stress, mitochondrial respiration, and neural transduction as well as the modulation of the AAs (Proline, Glycine and Alanine). This is the first study to suggest that LOE displayed by Cu-stressed fish may involve the disruption to GABAergic proteins and the calcium-dependent inhibitory neurotransmitter GABA. Moreover, this study highlights that proteomics and AA analysis can be used to identify potential biomarkers for environmental monitoring.

RNA-seq transcriptome and pathway analysis of the medicinal mushroom Lignosus tigris (Polyporaceae) offer insights into its bioactive compounds with anticancer and antioxidant potential

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal mushrooms belonging to the Lignosus spp., colloquially known as Tiger Milk mushrooms (TMMs), are used as traditional medicine by communities across various regions of China and Southeast Asia to enhance immunity and to treat various diseases. At present, three Lignosus species have been identified in Malaysia: L. rhinocerus, L. tigris, and L. cameronensis. Similarities in their macroscopic morphologies and the nearly indistinguishable appearance of their sclerotia often lead to interchangeability between them. Hence, substantiation of their traditional applications via identification of their individual bioactive properties is imperative in ensuring that they are safe for consumption. L. tigris was first identified in 2013. Thus far, studies on L. tigris cultivar sclerotia (Ligno TG-K) have shown that it possesses significant antioxidant activities and has greater antiproliferative action against selected cancer cells in vitro compared to its sister species, L. rhinocerus TM02®. Our previous genomics study also revealed significant genetic dissimilarities between them. Further omics investigations on Ligno TG-K hold immense potential in facilitating the identification of its bioactive compounds and their associated bioactivities.

AIM OF STUDY

The overall aim of this study was to investigate the gene expression profile of Ligno TG-K via de novo RNA-seq and pathway analysis. We also aimed to identify highly expressed genes encoding compounds that contribute to its cytotoxic and antioxidant properties, as well as perform a comparative transcriptomics analysis between Ligno TG-K and its sister species, L. rhinocerus TM02®.

MATERIALS AND METHODS

Total RNA from fresh 3-month-old cultivated L. tigris sclerotia (Ligno TG-K) was extracted and analyzed via de novo RNA sequencing. Expressed genes were analyzed using InterPro and NCBI-Nr databases for domain identification and homology search. Functional categorization based on gene functions and pathways was performed using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Clusters of Orthologous Genes (COG) databases. Selected genes were subsequently subjected to phylogenetic analysis.

RESULTS

Our transcriptomics analysis of Ligno TG-K revealed that 68.06% of its genes are expressed in the sclerotium; 80.38% of these were coding transcripts. Our analysis identified highly expressed transcripts encoding proteins with prospective medicinal properties. These included serine proteases (FPKM = 7356.68), deoxyribonucleases (FPKM = 3777.98), lectins (FPKM = 3690.87), and fungal immunomodulatory proteins (FPKM = 2337.84), all of which have known associations with anticancer activities. Transcripts linked to proteins with antioxidant activities, such as superoxide dismutase (FPKM = 1161.69) and catalase (FPKM = 1905.83), were also highly expressed. Results of our sequence alignments revealed that these genes and their orthologs can be found in other mushrooms. They exhibit significant sequence similarities, suggesting possible parallels in their anticancer and antioxidant bioactivities.

CONCLUSION

This study is the first to provide a reference transcriptome profile of genes expressed in the sclerotia of L. tigris. The current study also presents distinct COG profiles of highly expressed genes in Ligno TG-K and L. rhinocerus TM02®, highlighting that any distinctions uncovered may be attributed to their interspecies variations and inherent characteristics that are unique to each species. Our findings suggest that Ligno TG-K contains bioactive compounds with prospective medicinal properties that warrant further investigations.

CLASSIFICATION

Systems biology and omics.

Exploring Therapeutic Potential of Catalase: Strategies in Disease Prevention and Management

The antioxidant defense mechanisms play a critical role in mitigating the deleterious effects of reactive oxygen species (ROS). Catalase stands out as a paramount enzymatic antioxidant. It efficiently catalyzes the decomposition of hydrogen peroxide (H2O2) into water and oxygen, a potentially harmful byproduct of cellular metabolism. This reaction detoxifies H2O2 and prevents oxidative damage. Catalase has been extensively studied as a therapeutic antioxidant. Its applications range from direct supplementation in conditions characterized by oxidative stress to gene therapy approaches to enhance endogenous catalase activity. The enzyme's stability, bioavailability, and the specificity of its delivery to target tissues are significant hurdles. Furthermore, studies employing conventional catalase formulations often face issues related to enzyme purity, activity, and longevity in the biological milieu. Addressing these challenges necessitates rigorous scientific inquiry and well-designed clinical trials. Such trials must be underpinned by sound experimental designs, incorporating advanced catalase formulations or novel delivery systems that can overcome existing limitations. Enhancing catalase's stability, specificity, and longevity in vivo could unlock its full therapeutic potential. It is necessary to understand the role of catalase in disease-specific contexts, paving the way for precision antioxidant therapy that could significantly impact the treatment of diseases associated with oxidative stress.

Secretome profiling reveals acute changes in oxidative stress, brain homeostasis, and coagulation following short-duration spaceflight

As spaceflight becomes more common with commercial crews, blood-based measures of crew health can guide both astronaut biomedicine and countermeasures. By profiling plasma proteins, metabolites, and extracellular vesicles/particles (EVPs) from the SpaceX Inspiration4 crew, we generated "spaceflight secretome profiles," which showed significant differences in coagulation, oxidative stress, and brain-enriched proteins. While >93% of differentially abundant proteins (DAPs) in vesicles and metabolites recovered within six months, the majority (73%) of plasma DAPs were still perturbed post-flight. Moreover, these proteomic alterations correlated better with peripheral blood mononuclear cells than whole blood, suggesting that immune cells contribute more DAPs than erythrocytes. Finally, to discern possible mechanisms leading to brain-enriched protein detection and blood-brain barrier (BBB) disruption, we examined protein changes in dissected brains of spaceflight mice, which showed increases in PECAM-1, a marker of BBB integrity. These data highlight how even short-duration spaceflight can disrupt human and murine physiology and identify spaceflight biomarkers that can guide countermeasure development.

Recent Progress in Anti-Tumor Nanodrugs Based on Tumor Microenvironment Redox Regulation

The growth state of tumor cells is strictly affected by the specific abnormal redox status of the tumor microenvironment (TME). Moreover, redox reactions at the biological level are also central and fundamental to essential energy metabolism reactions in tumors. Accordingly, anti-tumor nanodrugs targeting the disruption of this abnormal redox homeostasis have become one of the hot spots in the field of nanodrugs research due to the effectiveness of TME modulation and anti-tumor efficiency mediated by redox interference. This review discusses the latest research results of nanodrugs in anti-tumor therapy, which regulate the levels of oxidants or reductants in TME through a variety of therapeutic strategies, ultimately breaking the original "stable" redox state of the TME and promoting tumor cell death. With the gradual deepening of study on the redox state of TME and the vigorous development of nanomaterials, it is expected that more anti-tumor nano drugs based on tumor redox microenvironment regulation will be designed and even applied clinically.

Salinity decline promotes growth and harmful blooms of a toxic alga by diverting carbon flow

Global climate change intensifies the water cycle and makes freshest waters become fresher and vice-versa. But how this change impacts phytoplankton in coastal, particularly harmful algal blooms (HABs), remains poorly understood. Here, we monitored a coastal bay for a decade and found a significant correlation between salinity decline and the increase of Karenia mikimotoi blooms. To examine the physiological linkage between salinity decreases and K. mikimotoi blooms, we compare chemical, physiological and multi-omic profiles of this species in laboratory cultures under high (33) and low (25) salinities. Under low salinity, photosynthetic efficiency and capacity as well as growth rate and cellular protein content were significantly higher than that under high salinity. More strikingly, the omics data show that low salinity activated the glyoxylate shunt to bypass the decarboxylation reaction in the tricarboxylic acid cycle, hence redirecting carbon from CO2 release to biosynthesis. Furthermore, the enhanced glyoxylate cycle could promote hydrogen peroxide metabolism, consistent with the detected decrease in reactive oxygen species. These findings suggest that salinity declines can reprogram metabolism to enhance cell proliferation, thus promoting bloom formation in HAB species like K. mikimotoi, which has important ecological implications for future climate-driven salinity declines in the coastal ocean with respect to HAB outbreaks.

Genetic Mutations and Mitochondrial Redox Signaling as Modulating Factors in Hypertrophic Cardiomyopathy: A Scoping Review

Hypertrophic cardiomyopathy (HCM) is a heart condition characterized by cellular and metabolic dysfunction, with mitochondrial dysfunction playing a crucial role. Although the direct relationship between genetic mutations and mitochondrial dysfunction remains unclear, targeting mitochondrial dysfunction presents promising opportunities for treatment, as there are currently no effective treatments available for HCM. This review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Extension for Scoping Reviews guidelines. Searches were conducted in databases such as PubMed, Embase, and Scopus up to September 2023 using "MESH terms". Bibliographic references from pertinent articles were also included. Hypertrophic cardiomyopathy (HCM) is influenced by ionic homeostasis, cardiac tissue remodeling, metabolic balance, genetic mutations, reactive oxygen species regulation, and mitochondrial dysfunction. The latter is a common factor regardless of the cause and is linked to intracellular calcium handling, energetic and oxidative stress, and HCM-induced hypertrophy. Hypertrophic cardiomyopathy treatments focus on symptom management and complication prevention. Targeted therapeutic approaches, such as improving mitochondrial bioenergetics, are being explored. This includes coenzyme Q and elamipretide therapies and metabolic strategies like therapeutic ketosis. Understanding the biomolecular, genetic, and mitochondrial mechanisms underlying HCM is crucial for developing new therapeutic modalities.

Protein Tyrosine Phosphatase regulation by Reactive Oxygen Species

Protein Tyrosine Phosphatases (PTPs) help to maintain the balance of protein phosphorylation signals that drive cell division, proliferation, and differentiation. These enzymes are also well-suited to redox-dependent signaling and oxidative stress response due to their cysteine-based catalytic mechanism, which requires a deprotonated thiol group at the active site. This review focuses on PTP structural characteristics, active site chemical properties, and vulnerability to change by reactive oxygen species (ROS). PTPs can be oxidized and inactivated by H2O2 through three non-exclusive mechanisms. These pathways are dependent on the coordinated actions of other H2O2-sensitive proteins, such as peroxidases like Peroxiredoxins (Prx) and Thioredoxins (Trx). PTPs undergo reversible oxidation by converting their active site cysteine from thiol to sulfenic acid. This sulfenic acid can then react with adjacent cysteines to form disulfide bonds or with nearby amides to form sulfenyl-amide linkages. Further oxidation of the sulfenic acid form to the sulfonic or sulfinic acid forms causes irreversible deactivation. Understanding the structural changes involved in both reversible and irreversible PTP oxidation can help with their chemical manipulation for therapeutic intervention. Nonetheless, more information remains unidentified than is presently known about the precise dynamics of proteins participating in oxidation events, as well as the specific oxidation states that can be targeted for PTPs. This review summarizes current information on PTP-specific oxidation patterns and explains how ROS-mediated signal transmission interacts with phosphorylation-based signaling machinery controlled by growth factor receptors and PTPs.

Structural and Functional Diversity of the Peroxiredoxin 6 Enzyme Family

Significance: Peroxiredoxins (Prdxs) with a single peroxidative cysteine (CP) in a conserved motif PXXX(T/S)XXCP within its thioredoxin fold, have been classified as the peroxiredoxin 6 (Prdx6 ) family. All Prdxs can reduce H2O2 and short chain hydroperoxides while Prdx6 in addition, can reduce phospholipid hydroperoxides (PLOOH) due to its ability to interact with peroxidized phospholipid substrate. The single CP of Prdx6 uses various external electron donors including glutathione thioredoxin, and ascorbic acid for resolution of its peroxidized state and, therefore, its peroxidase activity. Prdx6 proteins also exhibit Ca2+-independent phospholipase A2 (PLA2), lysophosphatidylcholine acyltransferase (LPCAT), and chaperone activities that depend on cellular localization and the oxidation and oligomerisation states of the protein. Thus, Prdx6 is a "moonlighting" enzyme. Recent Advance: Physiologically, Prdx6s have been reported to play an important role in protection against oxidative stress, repair of peroxidized cell membranes, mammalian lung surfactant turnover, activation of some NADPH oxidases, the regulation of seed germination in plants, as an indicator of cellular levels of reactive O2 species through Nrf-Klf9 activation, and possibly in male fertility, regulation of cell death through ferroptosis, cancer metastasis, and oxidative stress-related signalling pathways. Critical Issues: This review outlines Prdx6 enzyme unique structural features and explores its wide range of physiological functions. Yet, existing structural data falls short of fully revealing all of human Prdx6 multifunctional roles. Further endeavour is required to bridge this gap in its understanding. Although there are wide variations in both the structure and function of Prdx6 family members in various organisms, all Prdx6 proteins show the unique a long C-terminal extension that is also seen in Prdx1, but not in other Prdxs. Future Directions: As research data continues to accumulate, the potential for detailed insights into the role of C-terminal of Prdx6 in its oligomerisation and activities. There is a need for thorough exploration of structural characteristics of the various biological functions. Additionally, uncovering the interacting partners of Prdx6 and understanding its involvement in signalling pathways will significantly contribute to a more profound comprehension of its role.

The cytosolic hyperoxidation-sensitive and -robust Leishmania peroxiredoxins cPRX1 and cPRX2 are both dispensable for parasite infectivity

Typical two-cysteine peroxiredoxins (2-Cys-PRXs) are H2O2-metabolizing enzymes whose activity relies on two cysteine residues. Protists of the family Trypanosomatidae invariably express one cytosolic 2-Cys-PRX (cPRX1). However, the Leishmaniinae sub-family features an additional isoform (cPRX2), almost identical to cPRX1, except for the lack of an elongated C-terminus with a Tyr-Phe (YF) motif. Previously, cytosolic PRXs were considered vital components of the trypanosomatid antioxidant machinery. Here, we shed new light on the properties, functions and relevance of cPRXs from the human pathogen Leishmania infantum. We show first that LicPRX1 is sensitive to inactivation by hyperoxidation, mirroring other YF-containing PRXs participating in redox signaling. Using genetic fusion constructs with roGFP2, we establish that LicPRX1 and LicPRX2 can act as sensors for H2O2 and oxidize protein thiols with implications for signal transduction. Third, we show that while disrupting the LicPRX-encoding genes increases susceptibility of L. infantum promastigotes to external H2O2in vitro, both enzymes are dispensable for the parasites to endure the macrophage respiratory burst, differentiate into amastigotes and initiate in vivo infections. This study introduces a novel perspective on the functions of trypanosomatid cPRXs, exposing their dual roles as both peroxidases and redox sensors. Furthermore, the discovery that Leishmania can adapt to the absence of both enzymes has significant implications for our understanding of Leishmania infections and their treatment. Importantly, it questions the conventional notion that the oxidative response of macrophages during phagocytosis is a major barrier to infection and the suitability of cPRXs as drug targets for leishmaniasis.

Low-molecular-weight thiol transferases in redox regulation and antioxidant defence

Low-molecular-weight (LMW) thiols are produced in all living cells in different forms and concentrations. Glutathione (GSH), coenzyme A (CoA), bacillithiol (BSH), mycothiol (MSH), ergothioneine (ET) and trypanothione T(SH)2 are the main LMW thiols in eukaryotes and prokaryotes. LMW thiols serve as electron donors for thiol-dependent enzymes in redox-mediated metabolic and signaling processes, protect cellular macromolecules from oxidative and xenobiotic stress, and participate in the reduction of oxidative modifications. The level and function of LMW thiols, their oxidized disulfides and mixed disulfide conjugates in cells and tissues is tightly controlled by dedicated oxidoreductases, such as peroxiredoxins, glutaredoxins, disulfide reductases and LMW thiol transferases. This review provides the first summary of the current knowledge of structural and functional diversity of transferases for LMW thiols, including GSH, BSH, MSH and T(SH)2. Their role in maintaining redox homeostasis in single-cell and multicellular organisms is discussed, focusing in particular on the conjugation of specific thiols to exogenous and endogenous electrophiles, or oxidized protein substrates. Advances in the development of new research tools, analytical methodologies, and genetic models for the analysis of known LMW thiol transferases will expand our knowledge and understanding of their function in cell growth and survival under oxidative stress, nutrient deprivation, and during the detoxification of xenobiotics and harmful metabolites. The antioxidant function of CoA has been recently discovered and the breakthrough in defining the identity and functional characteristics of CoA S-transferase(s) is soon expected.

Antioxidant properties of α-amino acids: a density functional theory viewpoint

The antioxidant properties of 21 proteinogenic amino acids (AAs) and 3,4-dioxophenylanine (DOPA) have been studied in implicit water using density functional theory (DFT). All the calculations have been performed according to three oxidation mechanisms: (1) hydrogen-atom transfer (HAT); (2) single electron transfer followed by proton transfer (SET-PT); and (3) sequential proton-loss electron transfer (SPLET). As a result, five AAs with the highest antioxidant capacity have been established: DOPA, selenocysteine (Sec), tyrosine (Tyr), cysteine (Cys), and tryptophan (Trp). Also, global reactivity in terms of hardness/softness has been evaluated, as well as Fukui indices of local reactivity. Trp has been determined as the most reactive molecule, whereas selenium atom of Sec has been established as the most reactive atom. All the findings are in agreement with the recent literature on both experimental and theoretical studies of amino acids antioxidant activity. However, to the best of my knowledge, the calculations for one electron redox reactions of zwitterionic amino acids in implicit water have been performed for the first time.

Computational models as catalysts for investigating redoxin systems

Thioredoxin, glutaredoxin and peroxiredoxin systems play central roles in redox regulation, signaling and metabolism in cells. In these systems, reducing equivalents from NAD(P)H are transferred by coupled thiol-disulfide exchange reactions to redoxins which then reduce a wide array of targets. However, the characterization of redoxin activity has been unclear, with redoxins regarded as enzymes in some studies and redox metabolites in others. Consequently, redoxin activities have been quantified by enzyme kinetic parameters in vitro, and redox potentials or redox ratios within cells. By analyzing all the reactions within these systems, computational models showed that many kinetic properties attributed to redoxins were due to system-level effects. Models of cellular redoxin networks have also been used to estimate intracellular hydrogen peroxide levels, analyze redox signaling and couple omic and kinetic data to understand the regulation of these networks in disease. Computational modeling has emerged as a powerful complementary tool to traditional redoxin enzyme kinetic and cellular assays that integrates data from a number of sources into a single quantitative framework to accelerate the analysis of redoxin systems.

Temporal coordination of the transcription factor response to H2O2 stress

Oxidative stress from excess H2O2 activates transcription factors that restore redox balance and repair oxidative damage. Although many transcription factors are activated by H2O2, it is unclear whether they are activated at the same H2O2 concentration, or time. Dose-dependent activation is likely as oxidative stress is not a singular state and exhibits dose-dependent outcomes including cell-cycle arrest and cell death. Here, we show that transcription factor activation is both dose-dependent and coordinated over time. Low levels of H2O2 activate p53, NRF2 and JUN. Yet under high H2O2, these transcription factors are repressed, and FOXO1, NF-κB, and NFAT1 are activated. Time-lapse imaging revealed that the order in which these two groups of transcription factors are activated depends on whether H2O2 is administered acutely by bolus addition, or continuously through the glucose oxidase enzyme. Finally, we provide evidence that 2-Cys peroxiredoxins control which group of transcription factors are activated.

Mechanisms of chondrocyte regulated cell death in osteoarthritis: Focus on ROS-triggered ferroptosis, parthanatos, and oxeiptosis

Osteoarthritis (OA) is a common chronic inflammatory degenerative disease. Since chondrocytes are the only type of cells in cartilage, their survival is critical for maintaining cartilage morphology. This review offers a comprehensive analysis of how reactive oxygen species (ROS), including superoxide anions, hydrogen peroxide, hydroxyl radicals, nitric oxide, and their derivatives, affect cartilage homeostasis and trigger several novel modes of regulated cell death, including ferroptosis, parthanatos, and oxeiptosis, which may play roles in chondrocyte death and OA development. Moreover, we discuss potential therapeutic strategies to alleviate OA by scavenging ROS and provide new insight into the research and treatment of the role of regulated cell death in OA.

Lipid Peroxidation-Related Redox Signaling in Osteosarcoma

Oxidative stress and lipid peroxidation play important roles in numerous physiological and pathological processes, while the bioactive products of lipid peroxidation, lipid hydroperoxides and reactive aldehydes, act as important mediators of redox signaling in normal and malignant cells. Many types of cancer, including osteosarcoma, express altered redox signaling pathways. Such redox signaling pathways protect cancer cells from the cytotoxic effects of oxidative stress, thus supporting malignant transformation, and eventually from cytotoxic anticancer therapies associated with oxidative stress. In this review, we aim to explore the status of lipid peroxidation in osteosarcoma and highlight the involvement of lipid peroxidation products in redox signaling pathways, including the involvement of lipid peroxidation in osteosarcoma therapies.

Redox Regulation of Phosphatase and Tensin Homolog by Bicarbonate and Hydrogen Peroxide: Implication of Peroxymonocarbonate in Cell Signaling

Phosphatase and tensin homolog (PTEN) is a negative regulator of the phosphoinositide 3-kinases/protein kinase B (PI3K/AKT) signaling pathway. Notably, its active site contains a cysteine residue that is susceptible to oxidation by hydrogen peroxide (H2O2). This oxidation inhibits the phosphatase function of PTEN, critically contributing to the activation of the PI3K/AKT pathway. Upon the stimulation of cell surface receptors, the activity of NADPH oxidase (NOX) generates a transient amount of H2O2, serving as a mediator in this pathway by oxidizing PTEN. The mechanism underlying this oxidation, occurring despite the presence of highly efficient and abundant cellular oxidant-protecting and reducing systems, continues to pose a perplexing conundrum. Here, we demonstrate that the presence of bicarbonate (HCO3-) promoted the rate of H2O2-mediated PTEN oxidation, probably through the formation of peroxymonocarbonate (HCO4-), and consequently potentiated the phosphorylation of AKT. Acetazolamide (ATZ), a carbonic anhydrase (CA) inhibitor, was shown to diminish the oxidation of PTEN. Thus, CA can also be considered as a modulator in this context. In essence, our findings consolidate the crucial role of HCO3- in the redox regulation of PTEN by H2O2, leading to the presumption that HCO4- is a signaling molecule during cellular physiological processes.

Proteomic analysis of the mucus of the photosynthetic sea slug Elysia crispata

Elysia crispata is a tropical sea slug that can retain intracellular functional chloroplasts from its algae prey, a mechanism termed kleptoplasty. This sea slug, like other gastropods, secretes mucus, a viscous secretion with multiple functions, including lubrication, protection, and locomotion. This study presents the first comprehensive analysis of the mucus proteome of the sea slug E. crispata using gel electrophoresis and HPLC-MS/MS. We identified 306 proteins in the mucus secretions of this animal, despite the limited entries for E. crispata in the Uniprot database. The functional annotation of the mucus proteome using Gene Ontology identified proteins involved in different functions such as hydrolase activity (molecular function), carbohydrate-derived metabolic processes (biological processes) and cytoskeletal organization (cell component). Moreover, a high proportion of proteins with enzymatic activity in the mucus of E. crispata suggests potential biotechnological applications including antimicrobial and antitumor activities. Putative antimicrobial properties are reinforced by the high abundance of hydrolases. This study also identified proteins common in mucus samples from various species, supporting a common mechanism of mucus in protecting cells and tissues while facilitating animal movement. SIGNIFICANCE: Marine species are increasingly drawing the interest of researchers for their role in discovering new bioactive compounds. The study "Proteomic Analysis of the Mucus of the Photosynthetic Sea Slug Elysia crispata" is a pioneering effort that uncovers the complex protein content in this fascinating sea slug's mucus. This detailed proteomic study has revealed proteins with potential use in biotechnology, particularly for antimicrobial and antitumor purposes. This research is a first step in exploring the possibilities within the mucus of Elysia crispata, suggesting the potential for new drug discoveries. These findings could be crucial in developing treatments for severe diseases, especially those caused by multidrug-resistant bacteria, and may lead to significant advances in medical research.

Mitochondrial perturbation in immune cells enhances cell-mediated innate immunity in Drosophila

BACKGROUND

Mitochondria participate in various cellular processes including energy metabolism, apoptosis, autophagy, production of reactive oxygen species, stress responses, inflammation and immunity. However, the role of mitochondrial metabolism in immune cells and tissues shaping the innate immune responses are not yet fully understood. We investigated the effects of tissue-specific mitochondrial perturbation on the immune responses at the organismal level. Genes for oxidative phosphorylation (OXPHOS) complexes cI-cV were knocked down in the fruit fly Drosophila melanogaster, targeting the two main immune tissues, the fat body and the immune cells (hemocytes).

RESULTS

While OXPHOS perturbation in the fat body was detrimental, hemocyte-specific perturbation led to an enhanced immunocompetence. This was accompanied by the formation of melanized hemocyte aggregates (melanotic nodules), a sign of activation of cell-mediated innate immunity. Furthermore, the hemocyte-specific OXPHOS perturbation induced immune activation of hemocytes, resulting in an infection-like hemocyte profile and an enhanced immune response against parasitoid wasp infection. In addition, OXPHOS perturbation in hemocytes resulted in mitochondrial membrane depolarization and upregulation of genes associated with the mitochondrial unfolded protein response.

CONCLUSIONS

Overall, we show that while the effects of mitochondrial perturbation on immune responses are highly tissue-specific, mild mitochondrial dysfunction can be beneficial in immune-challenged individuals and contributes to variation in infection outcomes among individuals.

Insights into the Multifaceted Roles of Thioredoxin-1 System: Exploring Knockout Murine Models

Redox balance is increasingly identified as a major player in cellular signaling. A fundamentally simple reaction of oxidation and reduction of cysteine residues in cellular proteins is the central concept in this complex regulatory mode of protein function. Oxidation of key cysteine residues occurs at the physiological levels of reactive oxygen species (ROS), but they are reduced by a supply of thiol antioxidant molecules including glutathione, glutaredoxin, and thioredoxin. While these molecules show complex compensatory roles in experimental conditions, transgenic animal models provide a comprehensive picture to pinpoint the role of each antioxidant. In this review, we have specifically focused on the available literature on thioredoxin-1 system transgenic models that include thioredoxin and thioredoxin reductase proteins. As the identification of thioredoxin protein targets is technically challenging, the true contribution of this system in maintaining cellular balance remains unidentified, including the role of this system in the brain.

Surface Chemistry of Biologically Active Reducible Oxide Nanozymes

Reducible metal oxide nanozymes (rNZs) are a subject of intense recent interest due to their catalytic nature, ease of synthesis, and complex surface character. Such materials contain surface sites which facilitate enzyme-mimetic reactions via substrate coordination and redox cycling. Further, these surface reactive sites are shown to be highly sensitive to stresses within the nanomaterial lattice, the physicochemical environment, and to processing conditions occurring as part of their syntheses. When administered in vivo, a complex protein corona binds to the surface, redefining its biological identity and subsequent interactions within the biological system. Catalytic activities of rNZs each deliver a differing impact on protein corona formation, its composition, and in turn, their recognition, and internalization by host cells. Improving the understanding of the precise principles that dominate rNZ surface-biomolecule adsorption raises the question of whether designer rNZs can be engineered to prevent corona formation, or indeed to produce "custom" protein coronas applied either in vitro, and preadministration, or formed immediately upon their exposure to body fluids. Here, fundamental surface chemistry processes and their implications in rNZ material performance are considered. In particular, material structures which inform component adsorption from the application environment, including substrates for enzyme-mimetic reactions are discussed.

Antioxidant Systems as Modulators of Ferroptosis: Focus on Transcription Factors

Ferroptosis is a type of programmed cell death that differs from apoptosis, autophagy, and necrosis and is related to several physio-pathological processes, including tumorigenesis, neurodegeneration, senescence, blood diseases, kidney disorders, and ischemia-reperfusion injuries. Ferroptosis is linked to iron accumulation, eliciting dysfunction of antioxidant systems, which favor the production of lipid peroxides, cell membrane damage, and ultimately, cell death. Thus, signaling pathways evoking ferroptosis are strongly associated with those protecting cells against iron excess and/or lipid-derived ROS. Here, we discuss the interaction between the metabolic pathways of ferroptosis and antioxidant systems, with a particular focus on transcription factors implicated in the regulation of ferroptosis, either as triggers of lipid peroxidation or as ferroptosis antioxidant defense pathways.

The Mayo Clinic Salivary Tissue-Organoid Biobanking: A Resource for Salivary Regeneration Research

The salivary gland (SG) is an essential organ that secretes saliva, which supports versatile oral function throughout life, and is maintained by elusive epithelial stem and progenitor cells (SGSPC). Unfortunately, aging, drugs, autoimmune disorders, and cancer treatments can lead to salivary dysfunction and associated health consequences. Despite many ongoing therapeutic efforts to mediate those conditions, investigating human SGSPC is challenging due to lack of standardized tissue collection, limited tissue access, and inadequate purification methods. Herein, we established a diverse and clinically annotated salivary regenerative biobanking at the Mayo Clinic, optimizing viable salivary cell isolation and clonal assays in both 2D and 3D-matrigel growth environments. Our analysis identified ductal epithelial cells in vitro enriched with SGSPC expressing the CD24/EpCAM/CD49f+ and PSMA- phenotype. We identified PSMA expression as a reliable SGSPC differentiation marker. Moreover, we identified progenitor cell types with shared phenotypes exhibiting three distinct clonal patterns of salivary differentiation in a 2D environment. Leveraging innovative label-free unbiased LC-MS/MS-based single-cell proteomics, we identified 819 proteins across 71 single cell proteome datasets from purified progenitor-enriched parotid gland (PG) and sub-mandibular gland (SMG) cultures. We identified distinctive co-expression of proteins, such as KRT1/5/13/14/15/17/23/76 and 79, exclusively observed in rare, scattered salivary ductal basal cells, indicating the potential de novo source of SGSPC. We also identified an entire class of peroxiredoxin peroxidases, enriched in PG than SMG, and attendant H2O2-dependent cell proliferation in vitro suggesting a potential role for PRDX-dependent floodgate oxidative signaling in salivary homeostasis. The distinctive clinical resources and research insights presented here offer a foundation for exploring personalized regenerative medicine.

ROS-induced translational regulation-through spatiotemporal differences in codon recognition-is a key driver of brown adipogenesis

The role of translational regulation in brown adipogenesis is relatively unknown. Localized translation of mRNAs encoding mitochondrial components enables swift mitochondrial responses, but whether this occurs during brown adipogenesis, which involves massive mitochondrial biogenesis, has not been explored. Here, we used ribosome profiling and RNA-Seq, coupled with cellular fractionation, to obtain spatiotemporal insights into translational regulation. During brown adipogenesis, a translation bias towards G/C-ending codons is triggered first in the mitochondrial vicinity by reactive oxygen species (ROS), which later spreads to the rest of the cell. This translation bias is induced through ROS modulating the activity of the tRNA modification enzyme, ELP3. Intriguingly, functionally relevant mRNAs, including those encoding ROS scavengers, benefit from this bias; in so doing, ROS-induced translation bias both fuels differentiation and concurrently minimizes oxidative damage. These ROS-induced changes could enable sustained mitochondrial biogenesis during brown adipogenesis, and explain in part, the molecular basis for ROS hormesis.

Use of Oleuropein and Hydroxytyrosol for Cancer Prevention and Treatment: Considerations about How Bioavailability and Metabolism Impact Their Adoption in Clinical Routine

The fact that the Mediterranean diet could represent a source of natural compounds with cancer-preventive and therapeutic activity has been the object of great interest, especially with regard to the mechanisms of action of polyphenols found in olive oil and olive leaves. Secoiridoid oleuropein (OLE) and its derivative hydroxytyrosol (3,4-dihydroxyphenylethanol, HT) have demonstrated anti-proliferative properties against a variety of tumors and hematological malignancies both in vivo and in vitro, with measurable effects on cellular redox status, metabolism, and transcriptional activity. With this review, we aim to summarize the most up-to-date information on the potential use of OLE and HT for cancer treatment, making important considerations about OLE and HT bioavailability, OLE- and HT-mediated effects on drug metabolism, and OLE and HT dual activity as both pro- and antioxidants, likely hampering their use in clinical routine. Also, we focus on the details available on the effects of nutritionally relevant concentrations of OLE and HT on cell viability, redox homeostasis, and inflammation in order to evaluate if both compounds could be considered cancer-preventive agents or new potential chemotherapy drugs whenever their only source is represented by diet.

Reactive Carbonyl Species and Protein Lipoxidation in Atherogenesis

Atherosclerosis is a multifactorial disease of medium and large arteries, characterized by the presence of lipid-rich plaques lining the intima over time. It is the main cause of cardiovascular diseases and death worldwide. Redox imbalance and lipid peroxidation could play key roles in atherosclerosis by promoting a bundle of responses, including endothelial activation, inflammation, and foam cell formation. The oxidation of polyunsaturated fatty acids generates various lipid oxidation products such as reactive carbonyl species (RCS), including 4-hydroxy alkenals, malondialdehyde, and acrolein. RCS covalently bind to nucleophilic groups of nucleic acids, phospholipids, and proteins, modifying their structure and activity and leading to their progressive dysfunction. Protein lipoxidation is the non-enzymatic post-translational modification of proteins by RCS. Low-density lipoprotein (LDL) oxidation and apolipoprotein B (apoB) modification by RCS play a major role in foam cell formation. Moreover, oxidized LDLs are a source of RCS, which form adducts on a huge number of proteins, depending on oxidative stress intensity, the nature of targets, and the availability of detoxifying systems. Many systems are affected by lipoxidation, including extracellular matrix components, membranes, cytoplasmic and cytoskeletal proteins, transcription factors, and other components. The mechanisms involved in lipoxidation-induced vascular dysfunction are not fully elucidated. In this review, we focus on protein lipoxidation during atherogenesis.

Monogenic Disorders of ROS Production and the Primary Anti-Oxidative Defense

Oxidative stress, characterized by an imbalance between the production of reactive oxygen species (ROS) and the cellular anti-oxidant defense mechanisms, plays a critical role in the pathogenesis of various human diseases. Redox metabolism, comprising a network of enzymes and genes, serves as a crucial regulator of ROS levels and maintains cellular homeostasis. This review provides an overview of the most important human genes encoding for proteins involved in ROS generation, ROS detoxification, and production of reduced nicotinamide adenine dinucleotide phosphate (NADPH), and the genetic disorders that lead to dysregulation of these vital processes. Insights gained from studies on inherited monogenic metabolic diseases provide valuable basic understanding of redox metabolism and signaling, and they also help to unravel the underlying pathomechanisms that contribute to prevalent chronic disorders like cardiovascular disease, neurodegeneration, and cancer.

The Tumor Suppressor SOCS1 Diminishes Tolerance to Oxidative Stress in Hepatocellular Carcinoma

SOCS1 is a tumor suppressor in hepatocellular carcinoma (HCC). Recently, we showed that a loss of SOCS1 in hepatocytes promotes NRF2 activation. Here, we investigated how SOCS1 expression in HCC cells affected oxidative stress response and modulated the cellular proteome. Murine Hepa1-6 cells expressing SOCS1 (Hepa-SOCS1) or control vector (Hepa-Vector) were treated with cisplatin or tert-butyl hydroperoxide (t-BHP). The induction of NRF2 and its target genes, oxidative stress, lipid peroxidation, cell survival and cellular proteome profiles were evaluated. NRF2 induction was significantly reduced in Hepa-SOCS1 cells. The gene and protein expression of NRF2 targets were differentially induced in Hepa-Vector cells but markedly suppressed in Hepa-SOCS1 cells. Hepa-SOCS1 cells displayed an increased induction of reactive oxygen species but reduced lipid peroxidation. Nonetheless, Hepa-SOCS1 cells treated with cisplatin or t-BHP showed reduced survival. GCLC, poorly induced in Hepa-SOCS1 cells, showed a strong positive correlation with NFE2L2 and an inverse correlation with SOCS1 in the TCGA-LIHC transcriptomic data. A proteomic analysis of Hepa-Vector and Hepa-SOCS1 cells revealed that SOCS1 differentially modulated many proteins involved in diverse molecular pathways, including mitochondrial ROS generation and ROS detoxification, through peroxiredoxin and thioredoxin systems. Our findings indicate that maintaining sensitivity to oxidative stress is an important tumor suppression mechanism of SOCS1 in HCC.