G-site residue S67 is involved in the fungicide-degrading activity of a tau class glutathione S-transferase from Carica papaya.

Thiram is a toxic fungicide extensively used for the management of pathogens in fruits. Although it is known that thiram degrades in plant tissues, the key enzymes involved in this process remain unexplored. In this study, we report that a tau class glutathione S-transferase (GST) from Carica papaya can degrade thiram. This enzyme was easily obtained by heterologous expression in Escherichia coli, showed low promiscuity toward other thiuram disulfides, and catalyzed thiram degradation under physiological reaction conditions. Site-directed mutagenesis indicated that G-site residue S67 shows a key influence for the enzymatic activity toward thiram, while mutation of residue S13, which reduced the GSH oxidase activity, did not significantly affect the thiram-degrading activity. The formation of dimethyl dithiocarbamate, which was subsequently converted into carbon disulfide, and dimethyl dithiocarbamoylsulfenic acid as the thiram degradation products suggested that thiram undergoes an alkaline hydrolysis that involves the rupture of the disulfide bond. Application of the GST selective inhibitor 4-chloro-7-nitro-2,1,3-benzoxadiazole reduced papaya peel thiram-degrading activity by 95%, indicating that this is the main degradation route of thiram in papaya. GST from Carica papaya also catalyzed the degradation of the fungicides chlorothalonil and thiabendazole, with residue S67 showing again a key influence for the enzymatic activity. These results fill an important knowledge gap in understanding the catalytic promiscuity of plant GSTs and reveal new insights into the fate and degradation products of thiram in fruits.

Redox biomarkers in asymptomatic latent human tuberculosis: a comparison with active disease.

BACKGROUND: The latent TB infection (LTBI) is an asymptomatic infection caused by Mycobacterium tuberculosis (M.bt). Previous studies have shown a host-protective role for Heme oxygenase-1 (HO-1) during Mtb infection and an important involvement of Glutathione peroxidase-4 (Gpx4) in the necrotic pathology of the disease. Furthermore, increasing evidence suggested a crucial role for Glutathione in the granulomatous response to M. tb infection, with altered GSH levels associated to decreased host resistance. The aim of this study was to provide additional tools for discriminating the pathologic TB state and the asymptomatic infection. METHODS: We analyzed the gene expression of HO-1 and Gpx4 enzymes in blood of subjects with LTBI, active TB and healthy controls, and we also measured blood levels of the reduced (GSH) and oxidized (GSSG) forms of glutathione, together with the evaluation of GCL expression, the gene responsible for the GSH de novo synthesis. RESULTS: Our findings highlight a shift of glutathione homeostasis towards a more reducing conditions in LTBI, and a different modulation of GSH-dependent genes and HO-1 expression respect to active TB. CONCLUSION: This study can provide useful tools to understand the redox background that address the infection toward the asymptomatic or active disease.

Electroacupuncture suppresses neuronal ferroptosis to relieve chronic neuropathic pain.

Growing evidence supports the analgesic efficacy of electroacupuncture (EA) in managing chronic neuropathic pain (NP) in both patients and NP models induced by peripheral nerve injury. However, the underlying mechanisms remain incompletely understood. Ferroptosis, a novel form of programmed cell death, has been found to be activated during NP development, while EA has shown potential in promoting neurological recovery following acute cerebral injury by targeting ferroptosis. In this study, to investigate the detailed mechanism underlying EA intervention on NP, male Sprague-Dawley rats with chronic constriction injury (CCI)-induced NP model received EA treatment at acupoints ST36 and GV20 for 14 days. Results demonstrated that EA effectively attenuated CCI-induced pain hypersensitivity and mitigated neuron damage and loss in the spinal cord of NP rats. Moreover, EA reversed the oxidative stress-mediated spinal ferroptosis phenotype by upregulating reduced expression of xCT, glutathione peroxidase 4 (GPX4), ferritin heavy chain (FTH1) and superoxide dismutase (SOD) levels, and downregulating increased expression of acyl-CoA synthetase long-chain family member 4 (ACSL4), malondialdehyde levels and iron overload. Furthermore, EA increased the immunofluorescence co-staining of GPX4 in neurons cells of the spinal cord of CCI rats. Mechanistic analysis unveiled that the inhibition of antioxidant pathway of Nrf2 signalling via its specific inhibitor, ML385, significantly countered EA's protective effect against neuronal ferroptosis in NP rats while marginally diminishing its analgesic effect. These findings suggest that EA treatment at acupoints ST36 and GV20 may protect against NP by inhibiting neuronal ferroptosis in the spinal cord, partially through the activation of Nrf2 signalling.

Induction of stearoyl-CoA desaturase confers cell density-dependent ferroptosis resistance in melanoma.

Ferroptosis is a form of regulated cell death that is induced by inhibiting glutathione peroxidase 4 (GPX4), which eliminates lipid peroxidation. Ferroptosis induction is influenced by the cell environment. However, the cellular states altering ferroptosis susceptibility remain largely unknown. We found that melanoma cell lines became resistant to ferroptosis as cell density increased. Comparative transcriptome and metabolome analyses revealed that cell density-dependent ferroptosis resistance was coupled with a shift toward a lipogenic phenotype accompanied by strong induction of stearoyl-CoA desaturase (SCD). Database analysis of gene dependency across hundreds of cancer cell lines uncovered a negative correlation between GPX4 and SCD dependency. Importantly, SCD inhibition, either pharmacologically or through genetic knockout, sensitized melanoma cells to GPX4 inhibition, thereby attenuating ferroptosis resistance in cells at high density. Our findings indicate that transition to an SCD-inducing, lipogenic cell state produces density-dependent resistance to ferroptosis, which may provide a therapeutic strategy against melanoma.

Reactive nitrogen species act as the enhancers of glutathione pool in embryonic axes of apple seeds subjected to accelerated ageing.

MAIN CONCLUSION: Reactive nitrogen species mitigate the deteriorative effect of accelerated seed ageing by affecting the glutathione concentration and activities of GR and GPX-like. The treatment of apple (Malus domestica Borkh.) embryos isolated from accelerated aged seeds with nitric oxide-derived compounds increases their vigour and is linked to the alleviation of the negative effect of excessive oxidation processes. Reduced form of glutathione (GSH) is involved in the maintenance of redox potential. Glutathione peroxidase-like (GPX-like) uses GSH and converts it to oxidised form (GSSG), while glutathione reductase (GR) reduces GSSG into GSH. The aim of this work was to investigate the impact of the short-time NOx treatment of embryos isolated from apple seeds subjected to accelerated ageing on glutathione-related parameters. Apple seeds were subjected to accelerated ageing for 7, 14 or 21 days. Isolated embryos were shortly treated with NOx and cultured for 48 h. During ageing, in the axes of apple embryos, GSH and GSSG levels as well as half-cell reduction potential remained stable, while GR and GPX-like activities decreased. However, the positive effect of NOx in the vigour preservation of embryos isolated from prolonged aged seeds is linked to the increased total glutathione pool, and above all, higher GSH content. Moreover, NOx increased the level of transcripts encoding GPX-like and stimulated enzymatic activity. The obtained results indicate that high seed vigour related to the mode of action of NO and its derivatives is closely linked to the maintenance of higher GSH levels.

Nanomedicine-mediated recovery of antioxidant glutathione peroxidase activity after oxidative-stress cellular damage: Insights for neurological long COVID.

Nanomedicine for treating post-viral infectious disease syndrome is at an emerging stage. Despite promising results from preclinical studies on conventional antioxidants, their clinical translation as a therapy for treating post-COVID conditions remains challenging. The limitations are due to their low bioavailability, instability, limited transport to the target tissues, and short half-life, requiring frequent and high doses. Activating the immune system during coronavirus (SARS-CoV-2) infection can lead to increased production of reactive oxygen species (ROS), depleted antioxidant reserve, and finally, oxidative stress and neuroinflammation. To tackle this problem, we developed an antioxidant nanotherapy based on lipid (vesicular and cubosomal types) nanoparticles (LNPs) co-encapsulating ginkgolide B and quercetin. The antioxidant-loaded nanocarriers were prepared by a self-assembly method via hydration of a lyophilized mixed thin lipid film. We evaluated the LNPs in a new in vitro model for studying neuronal dysfunction caused by oxidative stress in coronavirus infection. We examined the key downstream signaling pathways that are triggered in response to potassium persulfate (KPS) causing oxidative stress-mediated neurotoxicity. Treatment of neuronally-derived cells (SH-SY5Y) with KPS (50 mM) for 30 min markedly increased mitochondrial dysfunction while depleting the levels of both glutathione peroxidase (GSH-Px) and tyrosine hydroxylase (TH). This led to the sequential activation of apoptotic and necrotic cell death processes, which corroborates with the crucial implication of the two proteins (GSH-Px and TH) in the long-COVID syndrome. Nanomedicine-mediated treatment with ginkgolide B-loaded cubosomes and vesicular LNPs showed minimal cytotoxicity and completely attenuated the KPS-induced cell death process, decreasing apoptosis from 32.6% (KPS) to 19.0% (MO-GB), 12.8% (MO-GB-Quer), 14.8% (DMPC-PEG-GB), and 23.6% (DMPC-PEG-GB-Quer) via free radical scavenging and replenished GSH-Px levels. These findings indicated that GB-LNPs-based nanomedicines may protect against KPS-induced apoptosis by regulating intracellular redox homeostasis.

Clinical and Prognostic Significance of Glutathione Peroxidase 2 in Lung Adenocarcinoma.

BACKGROUND: Glutathione peroxidase 2 (GPX2) is an antioxidant enzyme with an important role in tumor progression in various cancers. However, the clinical significance of GPX2 in lung adenocarcinoma has not been clarified. METHODS: Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to analyze GPX2 mRNA expression. Then, we conducted immunohistochemistry (IHC) to assess GPX2 expression in specimens acquired from 351 patients with lung adenocarcinoma who underwent surgery at Kyushu University from 2003 to 2012. We investigated the association between GPX2 expression and clinicopathological characteristics and further analyzed the prognostic relevance. RESULTS: qRT-PCR revealed that GPX2 mRNA expression was notably higher in tumor cells than in normal tissues. IHC revealed that high GPX2 expression (n = 175, 49.9%) was significantly correlated with male sex, smoking, advanced pathological stage, and the presence of pleural, lymphatic, and vascular invasion. Patients with high GPX2 expression exhibited significantly shorter recurrence-free survival (RFS) and overall survival. Multivariate analysis identified high GPX2 expression as an independent prognostic factor of RFS. CONCLUSIONS: GPX2 expression was significantly associated with pathological malignancy. It is conceivable that high GPX2 expression reflects tumor malignancy. Therefore, high GPX2 expression is a significant prognostic factor of poor prognosis for completely resected lung adenocarcinoma.

Hypermethylation of the glutathione peroxidase 4 gene promoter is associated with the occurrence of immune tolerance phase in chronic hepatitis B.

BACKGROUND: Hepatitis B virus (HBV) infection is a public health problem that seriously threatens human health. This study aimed to investigate the clinical significance of glutathione peroxidase 4(GPX4) in the occurrence and development of chronic hepatitis B (CHB). METHODS: A total of 169 participants including 137 patients with CHB and 32 healthy controls (HCs) were recruited. We detected the expression of GPX4 and stimulator of interferon genes (STING) in peripheral blood mononuclear cells (PBMCs) by real-time quantitative polymerase chain reaction (RT-qPCR). The methylation level of GPX4 gene promoter in PBMCs was detected by TaqMan probe-based quantitative methylation-specific PCR (MethyLight). Enzyme-linked immunosorbent assay (ELISA) was performed to detect the serum levels of GPX4, IFN-ß, oxidative stress (OS) related molecules, and pro-inflammatory cytokines. RESULTS: The expression levels of GPX4 in PBMCs and serum of CHB patients were lower than those of HCs, but the methylation levels of GPX4 promoter were higher than those of HCs, especially in patients at the immune tolerance phase. STING mRNA expression levels in PBMCs and serum IFN-ß levels of patients at the immune activation phase and reactivation phase of CHB were higher than those at other clinical phases of CHB and HCs. GPX4 mRNA expression level and methylation level in PBMCs from patients with CHB had a certain correlation with STING and IFN-ß expression levels. In addition, the methylation level of the GPX4 promoter in PBMCs from patients with CHB was correlated with molecules associated with OS and inflammation. CONCLUSIONS: GPX4 may play an important role in the pathogenesis and immune tolerance of CHB, which may provide new ideas for the functional cure of CHB.

Unveiling the protective role of sevoflurane in video-assisted thoracoscopic surgery associated-acute lung injury: Inhibition of ferroptosis.

Acute lung injury (ALI) frequently occurs after video-assisted thoracoscopic surgery (VATS). Ferroptosis is implicated in several lung diseases. Therefore, the disparate effects and underlying mechanisms of the two commonly used anesthetics (sevoflurane (Sev) and propofol) on VATS-induced ALI need to be clarified. In the present study, enrolled patients were randomly allocated to receive Sev (group S) or propofol anesthesia (group P). Intraoperative oxygenation, morphology of the lung tissue, expression of ZO-1, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), superoxide dismutase (SOD), glutathione (GSH), Fe2+, glutathione peroxidase 4 (GPX4), and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/nuclear factor erythroid-2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway in the lung tissue as well as the expression of TNF-α and IL-6 in plasma were measured. Postoperative complications were recorded. Of the 85 initially screened patients scheduled for VATS, 62 were enrolled in either group S (n = 32) or P (n = 30). Compared with propofol, Sev substantially (1) improved intraoperative oxygenation; (2) relieved histopathological lung injury; (3) increased ZO-1 protein expression; (4) decreased the levels of TNF-α and IL-6 in both the lung tissue and plasma; (5) increased the contents of GSH and SOD but decreased Fe2+ concentration; (6) upregulated the protein expression of p-AKT, Nrf2, HO-1, and GPX4. No significant differences in the occurrence of postoperative outcomes were observed between both groups. In summary, Sev treatment, in comparison to propofol anesthesia, may suppress local lung and systemic inflammatory responses by activating the PI3K/Akt/Nrf2/HO-1 pathway and inhibiting ferroptosis. This cascade of effects contributes to the maintenance of pulmonary epithelial barrier permeability, alleviation of pulmonary injury, and enhancement of intraoperative oxygenation in patients undergoing VATS.

Lysine acetyltransferase KAT2A modulates ferroptosis during colorectal cancer development.

BACKGROUND: Histone modifications, especially the lysine acetylation, have drawn increasing attention in cancer research area. The aim of this research is to explore the molecular mechanisms underlying the regulation of lysine acetyltransferase 2 A (KAT2A) on colorectal cancer (CRC). METHODS: Clinical samples were collected from patients with CRC. The expression and correlation between KAT2A and ferroptosis suppressor SLC7A11 and glutathione peroxidase 4 (GPX4) were measured by qPCR and Pearson correlation analysis. NCP cells were transfected with KAT2A overexpression vectors or siRNAs. The proliferation of cells was measured by CCK-8 and colony formation assay. Cell migration and invasion was analyzed by Transwell. The accumulation of lipid peroxidation, ferrous iron, and malondialdehyde (MDA) were analyzed to determine cell ferroptosis. The expression of cell metastasis biomarkers was measured by western blotting assay. Interaction between KAT2A with GPX4 gene was measured by chromatin immunoprecipitation (ChIP). RESULTS: The KAT2A, GPX4, and SLC7A11 expression was notably elevated in tumor tissues compared with the paired non-tumor tissues from CRC patients. The expression of KAT2A showed positive correlation with GPX4 and SLC7A11. Overexpression of KAT2A recovered the cell proliferation, migration, and invasion of CRC cells that suppressed by ferroptosis inducer erastin, along with deceased levels of ROS, iron, Fe2+, and MDA. Overexpression of KAT2A suppressed E-cadherin level and increased N-cadherin, Snail, and Vimentin expression in CRC cells. KAT2A interacted with GPX4 promoter region. CONCLUSIONS: In conclusion, our findings demonstrated that KAT2A modulates the histone acetylation of GPX4 to regulate proliferation, metastasis, and ferroptosis of CRC cells.

Relationship between Serum Concentrations and Muscular Expressions of Selenoproteins on Selenium-Supplemented Insulin Resistance Mouse Model.

Previously, insulin resistance and hepatic oxidative stress with increased expressions of glutathione peroxidase (GPx) 1 and selenoprotein P (SelP) were induced in NSY mice, a diabetic mouse model, by administrating a high fat diet (HFD) and seleno-L-methionine (SeMet) for 12 weeks. In this study we developed an analysis method for serum selenoproteins using LC-tandem mass spectrometry (LC-MS/MS) and investigated the effects of supplementary selenium on serum concentrations of selenoproteins as well as protein expression in skeletal muscle as a major insulin target tissue under the same experimental condition. The glucose area under the curves for oral glucose tolerance and insulin tolerance tests indicated that the HFD induced insulin resistance, whereas the treatment of SeMet + HFD showed insignificant promotion compared with the HFD-induced insulin resistance. Although the expressions of GPx1 in gastrocnemius and soleus were not significantly induced by supplementary SeMet nor HFD administration, the expressions of SelP in both skeletal muscles were significantly induced by the treatment of SeMet + HFD. There were also significant increases in serum concentrations of SelP by supplementary SeMet + HFD administration, whereas GPx3 was augmented by supplementary SeMet only. These results indicated that the HFD intake under the sufficient selenium status augmented the blood secretion of SelP, which may participate in the reduction of insulin sensitivity in skeletal muscles as well as liver or adipose tissues, and it is a better indicator of deterioration than GPx3 as it is a major selenoprotein in serum.

Ellagic acid ameliorates arsenic-induced neuronal ferroptosis and cognitive impairment via Nrf2/GPX4 signaling pathway.

Arsenic, a neurotoxic metalloid, poses significant health risks. However, ellagic acid, renowned for its antioxidant properties, has shown potential in neuroprotection. This study aimed to investigate the neuroprotective effects of ellagic acid against arsenic-induced neuronal ferroptosis and cognitive impairment and elucidate the underlying mechanisms. Using an arsenic-exposed Wistar rat model and an arsenic-induced HT22 cells model, we assessed cognitive ability, measured serum and brain arsenic levels, and evaluated pathological damage through histological analysis and transmission electron microscopy. Additionally, we examined oxidative stress and iron ion levels using GSH, MDA, ROS and tissue iron biochemical kits, and analyzed the expression of ferroptosis-related markers using western blot and qRT-PCR. Our results revealed that arsenic exposure increased both serum and brain arsenic levels, resulting in hippocampal pathological damage and subsequent decline in learning and memory abilities. Arsenic-induced neuronal ferroptosis was mediated by the inhibition of the xCT/GSH/GPX4/Nrf2 signaling axis and disruption of iron metabolism. Notably, ellagic acid intervention effectively reduced serum and brain arsenic levels, ameliorated neuronal damage, and improved oxidative stress, ferroptosis, and cognitive impairment. These beneficial effects were associated with the activation of the Nrf2/Keap1 signaling pathway, upregulation of GPX4 expression, and enhanced iron ion excretion. In conclusion, ellagic acid demonstrates promising neuroprotective effects against arsenic-induced neurotoxicity by mitigating neuronal ferroptosis and cognitive impairment.

The presence of virulence factor genes downregulates uterine AQP3 and alters glutathione peroxidase activity and uterine histopathology in canine pyometra.

Present study was designed to evaluate the role of virulence factor genes (papG, cnf1 and hylA) in the pathogenesis of canine pyometra. Antimicrobial susceptibility test and detection of virulence genes were performed Escherichia coli (E. coli) detected in uterine swab samples. Animals were divided into two groups based on the presence (VF+, n:14) or absence (VF-, n:7) of the virulence factor genes papG, cnf1 and hylA. Blood and tissue glutathione peroxidase activity, uterine histopathologic analysis and AQP3, ESR1, PGR, OXTR gene expressions were determined in both groups. Statistical analyses were performed using Stata version 15.1. All E. coli isolates were susceptible to amikacin, whereas resistant to ampicillin, amoxicillin/clavulanic acid and lincomycin. None of the isolates were susceptible to cefotaxime. E. coli isolates had at least one virulence gene. The most prevalent gene was fimH (100%), followed by fyuA (95.8%), usp (83.3%), sfa (75%), cnf1 and hlyA (70.8%) genes. Blood GPx activity was greater in VF+ animals. On the other hand, uterine tissue GPx activity was lower in VF+ group compared to the control group. Expression levels of AQP3 were upregulated more than fivefold in VF-dogs compared to the control group. In addition, AQP3 expression levels were found approximately threefold higher in VF (-) than VF (+) group (p < .05). Varying degree of inflammation noted for all animals with pyometra, but the presence of bacteria noted only in VF+ animals. In conclusion, the presence of virulence factor genes does not play a role in the histopathological degree of inflammation, the presence of bacteria was found to vary. Serum GPx activity increased in VF+ animals. While the hormone receptor expressions were similar, AQP expression was upregulated in the absence of virulence factor genes.

Post-GWAS multiomic functional investigation of the TNIP1 locus in Alzheimer's disease highlights a potential role for GPX3.

INTRODUCTION: Recent genome-wide association studies (GWAS) have reported a genetic association with Alzheimer's disease (AD) at the TNIP1/GPX3 locus, but the mechanism is unclear. METHODS: We used cerebrospinal fluid (CSF) proteomics data to test (n = 137) and replicate (n = 446) the association of glutathione peroxidase 3 (GPX3) with CSF biomarkers (including amyloid and tau) and the GWAS-implicated variants (rs34294852 and rs871269). RESULTS: CSF GPX3 levels decreased with amyloid and tau positivity (analysis of variance P = 1.5 × 10-5) and higher CSF phosphorylated tau (p-tau) levels (P = 9.28 × 10-7). The rs34294852 minor allele was associated with decreased GPX3 (P = 0.041). The replication cohort found associations of GPX3 with amyloid and tau positivity (P = 2.56 × 10-6) and CSF p-tau levels (P = 4.38 × 10-9). DISCUSSION: These results suggest variants in the TNIP1 locus may affect the oxidative stress response in AD via altered GPX3 levels. HIGHLIGHTS: Cerebrospinal fluid (CSF) glutathione peroxidase 3 (GPX3) levels decreased with amyloid and tau positivity and higher CSF phosphorylated tau. The minor allele of rs34294852 was associated with lower CSF GPX3. levels when also controlling for amyloid and tau category. GPX3 transcript levels in the prefrontal cortex were lower in Alzheimer's disease than controls. rs34294852 is an expression quantitative trait locus for GPX3 in blood, neutrophils, and microglia.

Characterization of GPX Gene Family in Pepper (Capsicum annuum L.) under Abiotic Stress and ABA Treatment.

Plant glutathione peroxidases (GPXs) are important enzymes for removing reactive oxygen species in plant cells and are closely related to the stress resistance of plants. This study identified the GPX gene family members of pepper (Capsicum annuum L.), "CM333", at the whole-genome level to clarify their expression patterns and enzyme activity changes under abiotic stress and ABA treatment. The results showed that eight CaGPX genes were unevenly distributed across four chromosomes and one scaffold of the pepper genome, and their protein sequences had Cys residues typical of the plant GPX domains. The analysis of collinearity, phylogenetic tree, gene structure, and conserved motifs indicated that the CaGPX gene sequence is conserved, structurally similar, and more closely related to the sequence structure of Arabidopsis. Meanwhile, many cis elements involved in stress, hormones, development, and light response were found in the promoter region of the CaGPX gene. In addition, CaGPX1/4 and CaGPX6 were basically expressed in all tissues, and their expression levels were significantly upregulated under abiotic stress and ABA treatment. Subcellular localization showed that CaGPX1 and CaGPX4 are localized in chloroplasts. Additionally, the variations in glutathione peroxidase activity (GSH-Px) mostly agreed with the variations in gene expression. In summary, the CaGPXs gene may play an important role in the development of peppers and their response to abiotic stress and hormones.

Glutathione-Dependent Pathways in Cancer Cells.

The most abundant tripeptide-glutathione (GSH)-and the major GSH-related enzymes-glutathione peroxidases (GPxs) and glutathione S-transferases (GSTs)-are highly significant in the regulation of tumor cell viability, initiation of tumor development, its progression, and drug resistance. The high level of GSH synthesis in different cancer types depends not only on the increasing expression of the key enzymes of the γ-glutamyl cycle but also on the changes in transport velocity of its precursor amino acids. The ability of GPxs to reduce hydroperoxides is used for cellular viability, and each member of the GPx family has a different mechanism of action and site for maintaining redox balance. GSTs not only catalyze the conjugation of GSH to electrophilic substances and the reduction of organic hydroperoxides but also take part in the regulation of cellular signaling pathways. By catalyzing the S-glutathionylation of key target proteins, GSTs are involved in the regulation of major cellular processes, including metabolism (e.g., glycolysis and the PPP), signal transduction, transcription regulation, and the development of resistance to anticancer drugs. In this review, recent findings in GSH synthesis, the roles and functions of GPxs, and GST isoforms in cancer development are discussed, along with the search for GST and GPx inhibitors for cancer treatment.

Antioxidant Enzymes and Their Potential Use in Breast Cancer Treatment.

According to the World Health Organization (WHO), breast cancer (BC) is the deadliest and the most common type of cancer worldwide in women. Several factors associated with BC exert their effects by modulating the state of stress. They can induce genetic mutations or alterations in cell growth, encouraging neoplastic development and the production of reactive oxygen species (ROS). ROS are able to activate many signal transduction pathways, producing an inflammatory environment that leads to the suppression of programmed cell death and the promotion of tumor proliferation, angiogenesis, and metastasis; these effects promote the development and progression of malignant neoplasms. However, cells have both non-enzymatic and enzymatic antioxidant systems that protect them by neutralizing the harmful effects of ROS. In this sense, antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), thioredoxin reductase (TrxR), and peroxiredoxin (Prx) protect the body from diseases caused by oxidative damage. In this review, we will discuss mechanisms through which some enzymatic antioxidants inhibit or promote carcinogenesis, as well as the new therapeutic proposals developed to complement traditional treatments.

The Role of Glutathione in Age-Related Macular Degeneration (AMD).

Age-related macular degeneration (AMD) is a chronic disease that usually develops in older people. Pathogenetic changes in this disease include anatomical and functional complexes. Harmful factors damage the retina and macula. These changes may lead to partial or total loss of vision. The disease can occur in two clinical forms: dry (the progression is slow and gentle) and exudative (wet-progression is acute and severe), which usually starts in the dry form; however, the coexistence of both forms is possible. The etiology of AMD is not fully understood, and the precise mechanisms of the development of this illness are still unknown. Extensive genetic studies have shown that AMD is a multi-factorial disease and that genetic determinants, along with external and internal environmental and metabolic-functional factors, are important risk factors. This article reviews the role of glutathione (GSH) enzymes engaged in maintaining the reduced form and polymorphism in glutathione S-transferase theta-1 (GSTT1) and glutathione S-transferase mu-1 (GSTM1) in the development of AMD. We only chose papers that confirmed the influence of the parameters on the development of AMD. Because GSH is the most important antioxidant in the eye, it is important to know the influence of the enzymes and genetic background to ensure an optimal level of glutathione concentration. Numerous studies have been conducted on how the glutathione system works till today. This paper presents the current state of knowledge about the changes in GSH, GST, GR, and GPx in AMD. GST studies clearly show increased activity in ill people, but for GPx, the results relating to activity are not so clear. Depending on the research, the results also suggest higher and lower GPx activity in patients with AMD. The analysis of polymorphisms in GST genes confirmed that mutations lead to weaker antioxidant barriers and may contribute to the development of AMD; unfortunately, a meta-analysis and some research did not confirm that connection. Unspecific results of many of the parameters that make up the glutathione system show many unknowns. It is so important to conduct further research to understand the exact mechanism of defense functions of glutathione against oxidative stress in the human eye.

Development of a Normal Porcine Cell Line Growing in a Heme-Supplemented, Serum-Free Condition for Cultured Meat.

A key element for the cost-effective development of cultured meat is a cell line culturable in serum-free conditions to reduce production costs. Heme supplementation in cultured meat mimics the original meat flavor and color. This study introduced a bacterial extract generated from Corynebacterium that was selected for high-heme expression by directed evolution. A normal porcine cell line, PK15, was used to apply the bacterial heme extract as a supplement. Consistent with prior research, we observed the cytotoxicity of PK15 to the heme extract at 10 mM or higher. However, after long-term exposure, PK15 adapted to tolerate up to 40 mM of heme. An RNA-seq analysis of these heme-adapted PK15 cells (PK15H) revealed a set of altered genes, mainly involved in cell proliferation, metabolism, and inflammation. We found that cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1), lactoperoxidase (LPO), and glutathione peroxidase 5 (GPX5) were upregulated in the PK15H heme dose dependently. When we reduced serum serially from 2% to serum free, we derived the PK15H subpopulation that was transiently maintained with 5-10 mM heme extract. Altogether, our study reports a porcine cell culturable in high-heme media that can be maintained in serum-free conditions and proposes a marker gene that plays a critical role in this adaptation process.

Curcumin mitigates ochratoxin A-induced oxidative stress and alters gene expression in broiler chicken liver and kidney.

The study aimed to evaluate the effect of curcumin (CURC) supplementation on broiler chickens exposed to ochratoxin A (OTA), by examining biochemical parameters and the expression of glutathione redox system genes and their regulation. OTA reduced glutathione content in the liver while increasing glutathione peroxidase activity. CURC showed no significant effects. Kidney parameters remained mostly unaffected. Gene expression analysis revealed OTA-induced upregulation of KEAP1, NRF2, AHR, GPx4 and GSR genes in the liver. CURC supplementation led to the upregulation of GPx4 and AHR genes with OTA+CURC treatment, resulting in the downregulation of GPx4, KEAP1, NRF2 and AHR genes compared to OTA treatment alone. In the kidney, GPx4 was downregulated, and NRF2 and AHR were upregulated as an effect of OTA, while CURC upregulated the NRF2 gene only. OTA+CURC treatment led to the downregulation of GPx4, GSS and AHR genes compared to the control and downregulation of NRF2 and AHR genes compared to OTA. The results suggested that CURC is partly effective against OTA-induced oxidative stress and that the effect of OTA and CURC on the antioxidant response is regulated through the KEAP1-NRF2-ARE and AHR pathways.