Identification, characterization, and crystal structure of the Omega class glutathione transferases

Regulation of Glutathione S-Transferase Omega 1 Mediated by Cysteine Residues Sensing the Redox Environment

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

Rattus norvegicus Glutathione Transferase Omega 1 Localization in Oral Tissues and Interactions with Food Phytochemicals

Glutathione transferases are xenobiotic-metabolizing enzymes with both glutathione-conjugation and ligandin roles. GSTs are present in chemosensory tissues and fluids of the nasal/oral cavities where they protect tissues from exogenous compounds, including food molecules. In the present study, we explored the presence of the omega-class glutathione transferase (GSTO1) in the rat oral cavity. Using immunohistochemistry, GSTO1 expression was found in taste bud cells of the tongue epithelium and buccal cells of the oral epithelium. Buccal and lingual extracts exhibited thiol-transferase activity (4.9 ± 0.1 and 1.8 ± 0.1 μM/s/mg, respectively). A slight reduction from 4.9 ± 0.1 to 4.2 ± 0.1 μM/s/mg (p < 0.05; Student's t test) was observed in the buccal extract with 100 μM GSTO1-IN-1, a specific inhibitor of GSTO1. RnGSTO1 exhibited the usual activities of omega GSTs, i.e., thiol-transferase (catalytic efficiency of 8.9 × 104 M-1·s-1), and phenacyl-glutathione reductase (catalytic efficiency of 8.9 × 105 M-1·s-1) activities, similar to human GSTO1. RnGSTO1 interacts with food phytochemicals, including bitter compounds such as luteolin (Ki = 3.3 ± 1.9 μM). Crystal structure analysis suggests that luteolin most probably binds to RnGSTO1 ligandin site. Our results suggest that GSTO1 could interact with food phytochemicals in the oral cavity.

Mycobacterium tuberculosis-dependent monocyte expression quantitative trait loci, cytokine production, and TB pathogenesis

Introduction

The heterogeneity of outcomes after Mycobacterium tuberculosis (Mtb) exposure is a conundrum associated with millennia of host-pathogen co-evolution. We hypothesized that human myeloid cells contain genetically encoded, Mtb-specific responses that regulate critical steps in tuberculosis (TB) pathogenesis.

Methods

We mapped genome-wide expression quantitative trait loci (eQTLs) in Mtb-infected monocytes with RNAseq from 80 Ugandan household contacts of pulmonary TB cases to identify monocyte-specific, Mtb-dependent eQTLs and their association with cytokine expression and clinical resistance to tuberculin skin test (TST) and interferon-γ release assay (IGRA) conversion.

Results

cis-eQTLs (n=1,567) were identified in Mtb-infected monocytes (FDR<0.01), including 29 eQTLs in 16 genes which were Mtb-dependent (significant for Mtb:genotype interaction [FDR<0.1], but not classified as eQTL in uninfected condition [FDR≥0.01]). A subset of eQTLs were associated with Mtb-induced cytokine expression (n=8) and/or clinical resistance to TST/IGRA conversion (n=1). Expression of BMP6, an Mtb-dependent eQTL gene, was associated with IFNB1 induction in Mtb-infected and DNA ligand-induced cells. Network and enrichment analyses identified fatty acid metabolism as a pathway associated with eQTL genes.

Discussion

These findings suggest that monocyte genes contain Mtb-dependent eQTLs, including a subset associated with cytokine expression and/or clinical resistance to TST/IGRA conversion, providing insight into immunogenetic pathways regulating susceptibility to Mtb infection and TB pathogenesis.

A dominance of Mu class glutathione transferases within the equine tapeworm Anoplocephala perfoliata

The most common equine tapeworm, Anoplocephala perfoliata, has often been neglected amongst molecular investigations and has been faced with limited treatment options. However, the recent release of a transcriptome dataset has now provided opportunities for in-depth analysis of A. perfoliata protein expression. Here, global, and sub-proteomic approaches were utilized to provide a comprehensive characterization of the A. perfoliata soluble glutathione transferases (GST) (ApGST). Utilizing both bioinformatics and gel-based proteomics, GeLC and 2D-SDS PAGE, the A. perfoliata ‘GST-ome’ was observed to be dominated with Mu class GST representatives. In addition, both Sigma and Omega class GSTs were identified, albeit to a lesser extent and absent from affinity chromatography approaches. Moreover, 51 ApGSTs were localized across somatic (47 GSTs), extracellular vesicles (EVs) (Whole: 1 GST, Surface: 2 GSTs) and EV depleted excretory secretory product (ESP) (9 GSTs) proteomes. In related helminths, GSTs have shown promise as novel anthelmintic or vaccine targets for improved helminth control. Thus, provides potential targets for understanding A. perfoliata novel infection mechanisms, host–parasite relationships and anthelmintic treatments.

Exploring Omega-3's Impact on the Expression of Bone-Related Genes in Meagre (Argyrosomus regius)

Dietary supplementation with Omega-3 fatty acids seems to promote skeletal health. Therefore, their consumption at imbalanced or excessive levels has offered less beneficial or even prejudicial effects. Fish produced in aquaculture regimes are prone to develop abnormal skeletons. Although larval cultures are usually fed with diets supplemented with Omega-3 Long Chain Polyunsaturated fatty acids (LC-PUFAs), the lack of knowledge about the optimal requirements for fatty acids or about their impact on mechanisms that regulate skeletal development has impeded the design of diets that could improve bone formation during larval stages when the majority of skeletal anomalies appear. In this study, Argyrosomus regius larvae were fed different levels of Omega-3s (2.6% and 3.6% DW on diet) compared to a commercial diet. At 28 days after hatching (DAH), their transcriptomes were analyzed to study the modulation exerted in gene expression dynamics during larval development and identify impacted genes that can contribute to skeletal formation. Mainly, both levels of supplementation modulated bone-cell proliferation, the synthesis of bone components such as the extracellular matrix, and molecules involved in the interaction and signaling between bone components or in important cellular processes. The 2.6% level impacted several genes related to cartilage development, denoting a special impact on endochondral ossification, delaying this process. However, the 3.6% level seemed to accelerate this process by enhancing skeletal development. These results offered important insights into the impact of dietary Omega-3 LC-PUFAs on genes involved in the main molecular mechanism and cellular processes involved in skeletal development.

Epigenetic regulation in lung cancer

Lung cancer is indeed a major cause of cancer-related deaths worldwide. The development of tumors involves a complex interplay of genetic, epigenetic, and environmental factors. Epigenetic mechanisms, including DNA methylation (DNAm), histone modifications, and microRNA expression, play a crucial role in this process. Changes in DNAm patterns can lead to the silencing of important genes involved in cellular functions, contributing to the development and progression of lung cancer. MicroRNAs and exosomes have also emerged as reliable biomarkers for lung cancer. They can provide valuable information about early diagnosis and treatment assessment. In particular, abnormal hypermethylation of gene promoters and its effects on tumorigenesis, as well as its roles in the Wnt signaling pathway, have been extensively studied. Epigenetic drugs have shown promise in the treatment of lung cancer. These drugs target the aberrant epigenetic modifications that are involved in the development and progression of the disease. Several factors have been identified as drug targets in non-small cell lung cancer. Recently, combination therapy has been discussed as a successful strategy for overcoming drug resistance. Overall, understanding the role of epigenetic mechanisms and their targeting through drugs is an important area of research in lung cancer treatment.

Glutathione and peroxisome redox homeostasis

Despite intensive research on peroxisome biochemistry, the role of glutathione in peroxisomal redox homeostasis has remained a matter of speculation for many years, and only recently has this issue started to be experimentally addressed. Here, we summarize and compare data from several organisms on the peroxisome-glutathione topic. It is clear from this comparison that the repertoire of glutathione-utilizing enzymes in peroxisomes of different organisms varies widely. In addition, the available data suggest that the kinetic connectivity between the cytosolic and peroxisomal pools of glutathione may also be different in different organisms, with some possessing a peroxisomal membrane that is promptly permeable to glutathione whereas in others this may not be the case. However, regardless of the differences, the picture that emerges from all these data is that glutathione is a crucial component of the antioxidative system that operates inside peroxisomes in all organisms.

Mycobacterium tuberculosis-dependent Monocyte Expression Quantitative Trait Loci and Tuberculosis Pathogenesis

The heterogeneity of outcomes after Mycobacterium tuberculosis (Mtb) exposure is a conundrum associated with millennia of host-pathogen co-evolution. We hypothesized that human myeloid cells contain genetically encoded, Mtb-specific responses that regulate critical steps in tuberculosis (TB) pathogenesis. We mapped genome-wide expression quantitative trait loci (eQTLs) in Mtb-infected monocytes with RNAseq from 80 Ugandan household contacts of pulmonary TB cases to identify monocyte-specific, Mtb-dependent eQTLs and their association with cytokine expression and clinical resistance to tuberculin skin test (TST) and interferon-γ release assay (IGRA) conversion. cis-eQTLs (n=1,567) were identified in Mtb-infected monocytes (FDR<0.01), including 29 eQTLs in 16 genes which were Mtb-dependent (significant for Mtb:genotype interaction [FDR<0.1], but not classified as eQTL in media condition [FDR≥0.01]). A subset of eQTLs were associated with Mtb-induced cytokine expression (n=8) and/or clinical resistance to TST/IGRA conversion (n=1). Expression of BMP6, an Mtb-dependent eQTL gene, was associated with IFNB1 induction in Mtb-infected and DNA ligand-induced cells. Network and enrichment analyses identified fatty acid metabolism as a pathway associated with eQTL genes. These findings suggest that monocyte genes contain Mtb-dependent eQTLs, including a subset associated with cytokine expression and/or clinical resistance to TST/IGRA conversion, providing insight into immunogenetic pathways regulating susceptibility to Mtb infection and TB pathogenesis.

Inhibition of glutathione S-transferase omega 1-catalyzed protein deglutathionylation suppresses adipocyte differentiation

Glutathione S-transferase omega 1 (GstO1) is closely associated with various human diseases, including obesity and diabetes, but its functional mechanism is not fully understood. In the present study, we found that the GstO1-specific inhibitor C1-27 effectively suppressed the adipocyte differentiation of 3T3-L1 preadipocytes. GstO1 expression was immediately upregulated upon the induction of adipocyte differentiation, and barely altered by C1-27. However, C1-27 significantly decreased the stability of GstO1. Moreover, GstO1 catalyzed the deglutathionylation of cellular proteins during the early phase of adipocyte differentiation, and C1-27 inhibited this activity. These results demonstrate that GstO1 is involved in adipocyte differentiation by catalyzing the deglutathionylation of proteins critical for the early phase of adipocyte differentiation. [BMB Reports 2023; 56(8): 457-462].

Chemistry and biology of enzymes in protein glutathionylation

Protein S-glutathionylation is emerging as a central oxidation that regulates redox signaling and biological processes linked to diseases. In recent years, the field of protein S-glutathionylation has expanded by developing biochemical tools for the identification and functional analyses of S-glutathionylation, investigating knockout mouse models, and developing and evaluating chemical inhibitors for enzymes involved in glutathionylation. This review will highlight recent studies of two enzymes, glutathione transferase omega 1 (GSTO1) and glutaredoxin 1 (Grx1), especially introducing their glutathionylation substrates associated with inflammation, cancer, and neurodegeneration and showcasing the advancement of their chemical inhibitors. Lastly, we will feature protein substrates and chemical inducers of LanC-like protein (LanCL), the first enzyme in protein C-glutathionylation.

The Polymorphisms in GSTO Genes (GSTO1 rs4925, GSTO2 rs156697, and GSTO2 rs2297235) Affect the Risk for Testicular Germ Cell Tumor Development: A Pilot Study

Members of the omega class of glutathione transferases (GSTs), GSTO1, and GSTO2, catalyze a range of reduction reactions as a part of the antioxidant defense system. Polymorphisms of genes encoding antioxidant proteins and the resultant altered redox profile have already been associated with the increased risk for testicular germ cell cancer (GCT) development. The aim of this pilot study was to assess the individual, combined, haplotype, and cumulative effect of GSTO1rs4925, GSTO2rs156697, and GSTO2rs2297235 polymorphisms with the risk for testicular GCT development, in 88 patients and 96 matched controls, through logistic regression models. We found that carriers of the GSTO1*C/A*C/C genotype exhibited an increased risk for testicular GCT development. Significant association with increased risk of testicular GCT was observed in carriers of GSTO2rs2297235*A/G*G/G genotype, and in carriers of combined GSTO2rs156697*A/G*G/G and GSTO2rs2297235*A/G*G/G genotypes. Haplotype H7 (GSTO1rs4925*C/GSTO2rs2297235*G/GSTO2rs156697*G) exhibited higher risk of testicular GCT, however, without significant association (p > 0.05). Finally, 51% of testicular GCT patients were the carriers of all three risk-associated genotypes, with 2.5-fold increased cumulative risk. In conclusion, the results of this pilot study suggest that GSTO polymorphisms might affect the protective antioxidant activity of GSTO isoenzymes, therefore predisposing susceptible individuals toward higher risk for testicular GCT development.

Identification of Omega-class glutathione transferases in helminths of the Taeniidae family

Glutathione transferase enzymes (GSTs) are believed to be a major detoxification system in helminth parasites and have been associated with immunomodulation of the host response. Echinococcus granulosus sensu lato (s.l.) is a cestode parasite known to express at least five different GSTs, but no Omega-class enzymes have been reported in this parasite or in any other cestode. Herein we report the identification of a new member of the GST superfamily in E. granulosus s.l., which is phylogenetically related to the Omega-class: EgrGSTO. Through mass spectrometry, we showed that the 237 amino acids protein EgrGSTO is expressed by the parasite. Moreover, we identified homologues of EgrGSTO in other eight members of the Taeniidae family, including E. canadensis, E. multilocularis, E. oligarthrus, Hydatigera taeniaeformis, Taenia asiatica, T. multiceps, T. saginata and T. solium. A manual sequence inspection and rational modification yielded eight Taeniidae's GSTO sequences, each one encoding for a 237 aa polypeptide showing 80.2% overall identity. To the best of our knowledge, this is the first description of genes encoding for Omega-class GSTs in worms belonging to the Taeniidae family -that at least in E. granulosus s.l. is expressed as a protein- suggesting the gene encodes for a functional protein.

Alpha-class glutathione S-transferases involved in the detoxification of aflatoxin B1 in ducklings

The objective of this study was to identify the key glutathione S-transferase (GST) isozymes involved in the detoxification of Aflatoxin B₁ (AFB₁) in ducks' primary hepatocytes. The full-length cDNA encoding the 10 GST isozymes (GST, GST3, GSTM3, MGST1, MGST2, MGST3, GSTK1, GSTT1, GSTO1 and GSTZ1) were isolated/synthesized from ducks' liver and cloned into the pcDNA3.1(+) vector. The results showed that pcDNA3.1(+)-GSTs plasmids were successfully transferred into the ducks' primary hepatocytes and the mRNA of the 10 GST isozymes were overexpressed by 1.9-3274.7 times. Compared to the control, 75 μg/L (IC₃₀) or 150 μg/L (IC₅₀) AFB₁ treatment reduced the cell viability by 30.0-50.0% and increased the LDH activity by 19.8-58.2% in the ducks' primary hepatocytes. Notably, the AFB₁-induced changes in cell viability and LDH activity were mitigated by overexpression of GST and GST3. Compared to the cells treated with AFB₁, exo-AFB₁-8,9-epoxide (AFBO)-GSH, as the major detoxified product of AFB₁, was increased in the cells overexpression of GST and GST3. Moreover, the sequences, phylogenetic and domain analysis revealed that the GST and GST3 were orthologous to Meleagris gallopavo GSTA3 and GSTA4. In conclusion, this study found that the ducks' GST and GST3 were orthologous to Meleagris gallopavo GSTA3 and GSTA4, which were involved in the detoxification of AFB₁ in ducks' primary hepatocytes.

Omega-Class Glutathione Transferases Protect DNA from Oxidative Stress in Pathogenic Helminth Reproductive Cells

Pathogenic helminths have evolved mechanisms to preserve reproductive function while surviving long-term in the host via robust protective responses. A protective role of antioxidant enzymes in preventing DNA degradation has long been proposed, but little evidence has been provided. Here, we show that omega-class glutathione transferases (GSTOs) are critical for maintaining viability by protecting the reproductive cell DNA of the carcinogenic liver fluke, Clonorchis sinensis. Clonorchis sinensis GSTO (CsGSTO) activities modified by changes in the GSH/GSSG and NADPH/NADP+ molar ratios suppressed the overproduction of reactive oxygen species. CsGSTO1 and CsGSTO2 catalyzed deglutathionylation under physiologic and low-stress conditions (GSH/GSSG ratio of 23:1 or higher) but promoted glutathionylation under high-stress conditions (GSH/GSSG ratio of 3:1 or lower). Gliotoxin-induced functional disruption of CsGSTOs in living C. sinensis reduced the GSH/GSSG molar ratio and increased the production of protein glutathionylation (PSSG) under physiologic and low-stress conditions, indicating that suppression of GSTO function did not affect deglutathionylation. However, the perturbation of CsGSTOs decreased the GSH/GSSG ratio but also reduced PSSG production under high oxidative stress, demonstrating that glutathionylation was impeded. In response to oxidative stimuli, C. sinensis decreased GSTO-specific dehydroascorbate reductase and thiol transferase activities and the GSH/GSSG ratio, while it increased the NADPH/NADP+ ratio and PSSG. CsGSTOs utilized GSH to regulate GSH/GSSG and NADPH/NADP+ recycling and triggered a redox signal leading to nuclear translocation. Nuclear-imported CsGSTOs were modified by glutathionylation to prevent DNA damage. Antibodies specific to CsGSTOs dose-dependently inhibited this process. Disruption of CsGSTOs or the depletion of GSH caused glutathionylation defects, leading to DNA degradation. Our results demonstrate that CsGSTOs and the GSH system play a previously unappreciated role in protecting DNA from oxidative stress.

Glutathione-Related Enzymes and Proteins: A Review

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

The Upregulation of GSTO2 is Associated with Colon Cancer Progression and a Poor Prognosis

Colorectal cancer is the second-leading cause of cancer-related mortality in the United States. Glutathione S-transferase can affect the development of cancer. Glutathione S-transferase omega 2, a member of the GST family, plays an important role in many tumors. However, the role of Glutathione S-transferase omega 2 in the development of colon cancer remains unclear. Herein, our study aimed to investigate the exact role of Glutathione S-transferase omega 2 in colon cancer. We used RNA sequencing data from The Cancer Genome Atlas and the Genotype-Tissue Expression database to analyze Glutathione S-transferase omega 2 expressions. Then, we explore the protein information of Glutathione S-transferase omega 2 in the Human Protein Atlas, GeneCards, and String database. In addition, western blot and immunohistochemistry were performed to evaluate the protein levels of Glutathione S-transferase omega 2 in colon cancer tissues. We acquire data from the Gene Expression Omnibus and The Cancer Genome Atlas databases. Also, we performed relevant prognostic analyses of these data. In addition, we performed a statistical analysis of the clinical data from The Cancer Genome Atlas database and the expression level of Glutathione S-transferase omega 2. Then, we performed Cox regression analysis and found independent risk factors for prognosis in patients with colon cancer. The Kyoto Encyclopedia of Genes and Genomes and Gene Ontology enrichment analyses were used to explore the potential biological functions of Glutathione S-transferase omega 2. The infiltration of colon cancer-immune cells was evaluated by the CIBERSORT method. RNA silencing was performed using siRNA constructs in HCT-116 and HT-29 cell lines. Cell Counting Kit-8 and EdU assays were performed to determine cell proliferation. Transwell experiments and scratch tests were used to determine cell migration. As for the mRNA and protein expression levels of cells, we used quantitative real-time PCR and western blot to detect them. Our research shows that Glutathione S-transferase omega 2 is overexpressed in colon cancer patients, and this overexpression is associated with a poor prognosis. The high expression of Glutathione S-transferase omega 2 is significantly correlated stage with stage, M, and N classification progression in colon cancer by statistical analysis. Univariate and multivariate Cox regression analyses showed that Glutathione S-transferase omega 2 was an independent risk factor for poor prognosis in colon cancer. In addition, we also found that Glutathione S-transferase omega 2 expression levels can affect the immune microenvironment of colon cancer cells. Gene silencing of Glutathione S-transferase omega 2 in HT-29 and HCT-116 cells significantly inhibited tumor growth and migration. In summary, we found that Glutathione S-transferase omega 2 can be used as a molecular indicator of colon cancer prognosis. In vitro, gene silencing of Glutathione S-transferase omega 2 inhibited colon cancer cells' growth and migration.

Differential susceptibility to arsenic in glutathione S-transferase omega 2 (GST-O2)-targeted freshwater water flea Daphnia magna mutants

To examine the role of glutathione S-transferase omega class (GST-O2) genes in the biotransformation and detoxification in Daphnia magna, various responses such as in vivo endpoints, arsenic speciation, enzymatic activities, and gene expression pathways related to arsenic metabolism were investigated in wild-type (WT) and GST-O2-mutant-type (MT) fleas produced by CRISPR/Cas9. Sensitivity to arsenic in MT fleas was higher than in WT fleas. Also, the reduction rate of arsenate (As^V) to arsenite (As^III) in the MT group was significantly lower and led to accumulation of higher arsenic concentrations, resulting in decreased protection against arsenic toxicity. Relative mRNA expression of other GST genes in the GST-O2-targeted MT group generally increased but the enzymatic activity of GST decreased compared with the WT group. Oxidative stress on arsenic exposure was more strongly induced in the MT group compared with the WT group, resulting in a decrease in the ability to defend against toxicity in GST-O2-targeted mutant D. magna. Our results suggest that GST-O2 plays an important role in arsenic biotransformation and detoxification functions in D. magna.

A metazoan-specific C-terminal motif in EXC-4 and Gα-Rho/Rac signaling regulate cell outgrowth during tubulogenesis in C. elegans

Chloride intracellular channels (CLICs) are conserved proteins for which the cellular and molecular functions remain mysterious. An important insight into CLIC function came from the discovery that Caenorhabditis elegans EXC-4/CLIC regulates morphogenesis of the excretory canal (ExCa) cell, a single-cell tube. Subsequent work showed that mammalian CLICs regulate vascular development and angiogenesis, and human CLIC1 can rescue exc-4 mutants, suggesting conserved function in biological tube formation (tubulogenesis) and maintenance. However, the cell behaviors and signaling pathways regulated by EXC-4/CLICs during tubulogenesis in vivo remain largely unknown. We report a new exc-4 mutation, affecting a C-terminal residue conserved in virtually all metazoan CLICs, that reveals a specific role for EXC-4 in ExCa outgrowth. Cell culture studies suggest a function for CLICs in heterotrimeric G protein (Gα/β/γ)-Rho/Rac signaling, and Rho-family GTPases are common regulators of cell outgrowth. Using our new exc-4 mutant, we describe a previously unknown function for Gα-encoding genes (gpa-12/Gα12/13, gpa-7/Gαi, egl-30/Gαq and gsa-1/Gαs), ced-10/Rac and mig-2/RhoG in EXC-4-mediated ExCa outgrowth. Our results demonstrate that EXC-4/CLICs are primordial players in Gα-Rho/Rac-signaling, a pathway that is crucial for tubulogenesis in C. elegans and in vascular development.

Possible Mechanisms of Resistance Development to Photodynamic Therapy (PDT) In Vulvar Cancer Cells

Photodynamic therapy (PDT) is a low-invasive treatment method that can be used to treat VIN patients. A photosensitizer (PS) applied to a patient is activated with use of the appropriate wavelength of light, which in an oxygen environment leads to the formation of a reactive oxygen species (ROS) that destroys the tumor. However, cells can protect themselves against these cytotoxic products by increasing their antioxidant mechanisms and repair capacity. Changes in the cytoskeleton may also influence resistance to PDT. Our results revealed that PDT-resistant cells changed the amount of ROS. Cells resistant to PDT A-431 exhibited a decreased ROS level and showed higher viability after oxidizing agent treatment. Resistant Cal-39 cells exhibited a decreased O₂^- level but increased other ROS. This provides protection from PDT but not from other oxidizing agents. Moreover, PDT leads to alterations in the cytoskeleton that may result in an epithelial-mesenchymal transition (EMT) or increased adhesion. Both EMT and cell adhesion may activate signaling pathways involved in survival. This means that resistance to PDT in vulvar cancer may be at least in part a result of changes in ROS level and alterations in the cytoskeleton.

Comparative analysis of detoxification-related gene superfamilies across five hemipteran species

Background

Hemiptera is one of the most speciose orders of insects, and the most speciose considering Hemimetabola. Through their evolutive history, hemipterans with different feeding habits have adapted to deal with different chemical challenges. Three major gene families are involved in xenobiotic detoxification in insects: the cytochromes P450 (CYPs), carboxyl/cholinesterases (CCEs), and glutathione transferases (GSTs). Here we perform a comparative analysis on the complement of these gene superfamilies across five hemipteran species; four heteropterans (the pentatomid plant feeders Nezara viridula and Halyomorpha halys; the hematophagous Cimex lectularius, Cimicidae, and Rhodnius prolixus, Reduviidae), and one Auchenorrhyncha plant feeder (Nilaparvata lugens).

Results

Our results point to an expansion of several enzyme families associated with xenobiotic detoxification in heteropterans with respect to other species and the existence of a dynamic evolution pattern including CYP3 clan, hormone and pheromone processing class in the CCE superfamily, and sigma class in GST superfamily. Other detoxification-related families are reduced in the hemipteran species analyzed here: reduction or even absence of epsilon class and reduced delta class in GST superfamily; absence of mitochondrial CYP12 family; absence of CYP9 family in CYP3 clan; and reduction or even absence of some dietary/detoxification groups of CCEs. Interestingly, the most polyphagous species analyzed here (H. halys) is also the one that presents the largest repertoire of detoxification enzymes. Gene cluster analysis suggests that this could be due to gene duplication events.

Conclusions

The evolutionary analysis performed here reveals characteristics that are both common and particular for heteropterans. The composition and organization of detoxification-related gene families could shed light on evolutionary forces that shaped their divergence. These families are important for both the detoxification of diet products and for conferring tolerance or resistance to synthetic insecticides. Furthermore, we present the first comprehensive analysis of detoxification gene superfamilies in N. viridula, an understudied species in spite of its economic relevance as a crop pest. The information obtained is of interest for basic insect science as well as for the control of harmful species and the management of insecticide resistance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08974-y.

In Vivo Glutathione S-Transferases Superfamily Proteome Analysis: An Insight into Aedes albopictus Mosquitoes upon Acute Xenobiotic Challenges

In this study, the induction of glutathione S-transferase (GST) enzymatic activities in Aedes albopictus under 24 h of xenobiotic challenges was investigated. From LCMS analysis, 23 GST isoforms were identified under Delta, Epsilon, Sigma, Zeta, Omega, and Iota classes, together with one GSTX1-1 isoform, in both treated and untreated samples. Using STRING 11.5, the functional enrichment network of Gene Ontology (GO) analysis, the identified peptides were found to be involved in the glutathione metabolic biological process (GO:0006749, p-value: 1.93 × 10−29), and the molecular functions involved are due to glutathione transferase (GO:0016848, p-value: 2.92 × 10−8) aside from carbon-halide lyase activity (GO:004364, p-value: 1.21 × 10−31). The Protein-Protein Interaction (PPI) network (STRING 11.5) showed significant interactions within the GST superfamily and some of the GST classes interacted with other proteins among the input domain of the identified peptides (p-value < 1.0 × 10−16). In TMT labeling for the quantification of peptide abundance, isoforms from Delta (GSTD1-2, GSTD1-3, GSTD1-4) and Epsilon (GSTE3-1, GSTE4-2) were found to be overexpressed (between 1.5-fold and 2-fold changes). In the PPI analysis, 12 common enriched pathways of Kyoto Encyclopedia of Genes and Genomes (KEGG) were found to be intercorrelated with the identified GSTs at PPI enrichment p-value < 1.0 × 10−16. Overall, this study indicates that distinct GST enzymes, which were identified up to their specific protein isoforms, are involved in the metabolic mechanisms underlying xenobiotic stress.

Molecular changes in oysters Crassostrea gigas (Thunberg, 1793) from aquaculture areas of Santa Catarina Island bays (Florianópolis, Brazil) reveal anthropogenic effects

Anthropogenic activities in coastal regions cause risks to the environmental and human health. Due to the carcinogenic and mutagenic potential, polycyclic aromatic hydrocarbons (PAH) are considered priority for monitoring. Most of the Brazilian production of Crassostrea gigas oysters are placed in the Bays of Santa Catarina Island. The aim of this study was to evaluate molecular responses (phase I and II of biotransformation and antioxidant defense) of C. gigas from six oyster farming areas potentially contaminated by sanitary sewage in Florianópolis Metropolitan (SC, Brazil): Santo Antônio de Lisboa, Sambaqui, Serraria, Caieira, Tapera, Imaruim. We evaluated the transcript levels of CYP1A1-like, CYP2-like, CYP2AU2-like, CYP356A1, GSTA1A-like, GSTO.4A-like, SULT-like, SOD-like and CAT-like by qRT-PCR. Only oysters from Caieira showed levels of thermotolerant coliforms allowed by the law. Chemicals analyses in soft tissues of oysters showed low to average levels of PAH in all monitored areas. Enhanced transcript levels of phase I (CYP1A1-like, CYP3564A1-like, CYP2-like and CYP2AU2-like) were observed in oysters from Serraria and Imaruí, suggesting higher biotransformation activity in these farming areas. Regarding phase II of biotransformation, GSTO.4A-like was up-regulated in oysters from Imaruí compared to Caieira and Santo Antônio de Lisboa. An upregulation of SOD-like and CAT-like were observed in oysters from Imaruí and Serraria, suggesting that oysters from these sites are facing higher prooxidant conditions compared to other areas. By integrating the biological and chemical data it is suggested that human-derived contaminants are affecting the oyster metabolism in some farming areas.

Biochemical and Structural Characterization of Chi-Class Glutathione Transferases: A Snapshot on the Glutathione Transferase Encoded by sll0067 Gene in the Cyanobacterium Synechocystis sp. Strain PCC 6803

Glutathione transferases (GSTs) constitute a widespread superfamily of enzymes notably involved in detoxification processes and/or in specialized metabolism. In the cyanobacterium Synechocsytis sp. PCC 6803, SynGSTC1, a chi-class GST (GSTC), is thought to participate in the detoxification process of methylglyoxal, a toxic by-product of cellular metabolism. A comparative genomic analysis showed that GSTCs were present in all orders of cyanobacteria with the exception of the basal order Gloeobacterales. These enzymes were also detected in some marine and freshwater noncyanobacterial bacteria, probably as a result of horizontal gene transfer events. GSTCs were shorter of about 30 residues compared to most cytosolic GSTs and had a well-conserved SRAS motif in the active site (¹⁰SRAS¹³ in SynGSTC1). The crystal structure of SynGSTC1 in complex with glutathione adopted the canonical GST fold with a very open active site because the α4 and α5 helices were exceptionally short. A transferred multipolar electron-density analysis allowed a fine description of the solved structure. Unexpectedly, Ser10 did not have an electrostatic influence on glutathione as usually observed in serinyl-GSTs. The S10A variant was only slightly less efficient than the wild-type and molecular dynamics simulations suggested that S10 was a stabilizer of the protein backbone rather than an anchor site for glutathione.

Anti-glutathione S-transferase omega 1-1 (GSTO1-1) antibodies are increased during acute and chronic inflammation in humans

Glutathione S-transferase omega-1 (GSTO1-1) is a cytosolic enzyme involved in the modulation of critical inflammatory pathways as well as in cancer progression. Auto-antibodies against GSTO1-1 were detected in the serum of patients with esophageal squamous cell carcinoma and were proposed as potential biomarkers in the early detection of the disease. Our findings show that anti-GSTO1-1 antibodies can be found in a variety of inflammatory diseases, including autoimmune rheumatoid arthritis, infectious SARS-CoV-2, and trichinellosis. Our findings strongly suggest that anti-GSTO1-1 antibodies may be a marker of tissue damage/inflammation rather than a specific tumor-associated biomarker.

Antioxidant Genetic Profile Modifies Probability of Developing Neurological Sequelae in Long-COVID

Understanding the sequelae of COVID-19 is of utmost importance. Neuroinflammation and disturbed redox homeostasis are suggested as prevailing underlying mechanisms in neurological sequelae propagation in long-COVID. We aimed to investigate whether variations in antioxidant genetic profile might be associated with neurological sequelae in long-COVID. Neurological examination and antioxidant genetic profile (SOD2, GPXs and GSTs) determination, as well as, genotype analysis of Nrf2 and ACE2, were conducted on 167 COVID-19 patients. Polymorphisms were determined by the appropriate PCR methods. Only polymorphisms in GSTP1AB and GSTO1 were independently associated with long-COVID manifestations. Indeed, individuals carrying GSTP1 Val or GSTO1 Asp allele exhibited lower odds of long-COVID myalgia development, both independently and in combination. Furthermore, the combined presence of GSTP1 Ile and GSTO1 Ala alleles exhibited cumulative risk regarding long-COVID myalgia in carriers of the combined GPX1 LeuLeu/GPX3 CC genotype. Moreover, individuals carrying combined GSTM1-null/GPX1LeuLeu genotype were more prone to developing long-COVID “brain fog”, while this probability further enlarged if the Nrf2 A allele was also present. The fact that certain genetic variants of antioxidant enzymes, independently or in combination, affect the probability of long-COVID manifestations, further emphasizes the involvement of genetic susceptibility when SARS-CoV-2 infection is initiated in the host cells, and also months after.

Gut Microbiota Metabolism of Azathioprine: A New Hallmark for Personalized Drug-Targeted Therapy of Chronic Inflammatory Bowel Disease

Despite the growing number of new drugs approved for the treatment of inflammatory bowel disease (IBD), the long-term clinical use of thiopurine therapy and the well-known properties of conventional drugs including azathioprine have made their place in IBD therapy extremely valuable. Despite the fact that thiopurine S-methyltransferase (TPMT) polymorphism has been recognized as a major cause of the interindividual variability in the azathioprine response, recent evidence suggests that there might be some yet unknown causes which complicate dosing strategies causing either failure of therapy or toxicity. Increasing evidence suggests that gut microbiota, with its ability to release microbial enzymes, affects the pharmacokinetics of numerous drugs and subsequently drastically alters clinical effectiveness. Azathioprine, as an orally administered drug which has a complex metabolic pathway, is the prime illustrative candidate for such microbial metabolism of drugs. Comprehensive databases on microbial drug-metabolizing enzymes have not yet been generated. This study provides insights into the current evidence on microbiota-mediated metabolism of azathioprine and systematically accumulates findings of bacteria that possess enzymes required for the azathioprine biotransformation. Additionally, it proposes concepts for the identification of gut bacteria species responsible for the metabolism of azathioprine that could aid in the prediction of dose-response effects, complementing pharmacogenetic approaches already applied in the optimization of thiopurine therapy of IBD. It would be of great importance to elucidate to what extent microbiota-mediated metabolism of azathioprine contributes to the drug outcomes in IBD patients which could facilitate the clinical implementation of novel tools for personalized thiopurine treatment of IBD.

Transcriptomic profile of the predatory mite Amblyseius swirskii (Acari: Phytoseiidae) on different host plants

Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) is a predatory mite, effective at controlling whiteflies and thrips in protected crops. However, on tomato its efficacy as a biocontrol agent is hindered, most probably by the plant trichomes and their exudates. Our aim was to characterize the response of A. swirskii to the tomato trichome exudates and identify three major detoxification gene sets in this species: cytochromes P450 (CYPs), glutathione S-transferases (GSTs) and carboxyl/cholinesterases (CCEs). Mites were exposed separately to tomato and pepper, a favourable host plant for A. swirskii, after which their transcriptional responses were analysed and compared. The de novo transcriptome assembly resulted in 71,336 unigenes with 66.1% of them annotated. Thirty-nine A. swirskii genes were differentially expressed after transfer on tomato leaves when compared to pepper leaves; some of the expressed genes were associated with the metabolism of tomato exudates. Our results illustrate that the detoxification gene sets CYPs, GSTs and CCEs are abundant in A. swirskii, but do not play a significant role when in contact with the tomato exudates.

GSTO1, GSTO2 and ACE2 Polymorphisms Modify Susceptibility to Developing COVID-19

Based on the close relationship between dysregulation of redox homeostasis and immune response in SARS-CoV-2 infection, we proposed a possible modifying role of ACE2 and glutathione transferase omega (GSTO) polymorphisms in the individual propensity towards the development of clinical manifestations in COVID-19. The distribution of polymorphisms in ACE2 (rs4646116), GSTO1 (rs4925) and GSTO2 (rs156697) were assessed in 255 COVID-19 patients and 236 matched healthy individuals, emphasizing their individual and haplotype effects on disease development and severity. Polymorphisms were determined by the appropriate qPCR method. The data obtained showed that individuals carrying variant GSTO1*AA and variant GSTO2*GG genotypes exhibit higher odds of COVID-19 development, contrary to ones carrying referent alleles (p = 0.044, p = 0.002, respectively). These findings are confirmed by haplotype analysis. Carriers of H2 haplotype, comprising GSTO1*A and GSTO2*G variant alleles were at 2-fold increased risk of COVID-19 development (p = 0.002). Although ACE2 (rs4646116) polymorphism did not exhibit a statistically significant effect on COVID-19 risk (p = 0.100), the risk of COVID-19 development gradually increased with the presence of each additional risk-associated genotype. Further studies are needed to clarify the specific roles of glutathione transferases omega in innate immune response and vitamin C homeostasis once the SARS-CoV-2 infection is initiated in the host cell.

The freshwater water flea Daphnia magna NIES strain genome as a resource for CRISPR/Cas9 gene targeting: The glutathione S-transferase omega 2 gene

The water flea Daphnia magna is a small freshwater planktonic animal in the Cladocera. In this study, we assembled the genome of the D. magna NIES strain, which is widely used for gene targeting but has no reported genome. We used the long-read sequenced data of the Oxford nanopore sequencing tool for assembly. Using 3,231 genetic markers, the draft genome of the D. magna NIES strain was built into ten linkage groups (LGs) with 483 unanchored contigs, comprising a genome size of 173.47 Mb. The N50 value of the genome was 12.54 Mb and the benchmarking universal single-copy ortholog value was 98.8%. Repeat elements in the D. magna NIES genome were 40.8%, which was larger than other Daphnia spp. In the D. magna NIES genome, 15,684 genes were functionally annotated. To assess the genome of the D. magna NIES strain for CRISPR/Cas9 gene targeting, we selected glutathione S-transferase omega 2 (GST-O2), which is an important gene for the biotransformation of arsenic in aquatic organisms, and targeted it with an efficient make-up (25.0%) of mutant lines. In addition, we measured reactive oxygen species and antioxidant enzymatic activity between wild type and a mutant of the GST-O2 targeted D. magna NIES strain in response to arsenic. In this study, we present the genome of the D. magna NIES strain using GST-O2 as an example of gene targeting, which will contribute to the construction of deletion mutants by CRISPR/Cas9 technology.

Loss of GSTO2 contributes to cell growth and mitochondria function via the p38 signaling in lung squamous cell carcinoma

Glutathione S-transferase omega 2 (GSTO2) lacks any appreciable GST activity, but it exhibits thioltransferase activity. The significance of GSTO2 in lung function has been reported; however, the precise expression and molecular function of GSTO2 in the lungs remain unclear. In the present study, we found that GSTO2 is expressed in airway basal cells, non-ciliated, columnar Clara cells, and type II alveolar cells, which have self-renewal capacity in the lungs. Contrastingly, no GSTO2 expression was observed in 94 lung squamous cell carcinoma (LSCC) samples. When human LSCC cell lines were treated with 5-aza-2'-deoxycytidine, a DNA-methyltransferase inhibitor, GSTO2 transcription was induced, suggesting that aberrant GSTO2 hypermethylation in LSCC is the cause of its downregulation. Forced GSTO2 expression in LSCC cell lines inhibited cell growth and colony formation in vitro. In a subcutaneous xenograft model, GSTO2-transfected cells formed smaller tumors in nude mice than mock-transfected cells. Upon intravenous injection into nude mice, the incidence of liver metastasis was lower in mice injected with GSTO2-transfected cells than in those injected with mock-transfected cells. In addition, GSTO2 induction suppressed the expression of β-catenin and the oxygen consumption rate, but it did not affect the extracellular acidification rate. Furthermore, GSTO2-transfected cells displayed lower mitochondrial membrane potential than mock-transfected cells. When GSTO2-transfected cells were treated with a p38 inhibitor, β-catenin expression and mitochondrial membrane potential were recovered. Our study indicated that the loss of GSTO2 via DNA hypermethylation contributes to the growth and progression of LSCC, probably by modulating cancer metabolism via the p38/β-catenin signaling pathway.

Proposed mechanism for monomethylarsonate reductase activity of human omega-class glutathione transferase GSTO1-1

Contamination of drinking water with toxic inorganic arsenic is a major public health issue. The mechanisms of enzymes and transporters in arsenic elimination are therefore of interest. The human omega-class glutathione transferases have been previously shown to possess monomethylarsonate (V) reductase activity. To further understanding of this activity, molecular dynamics of human GSTO1-1 bound to glutathione with a monomethylarsonate isostere were simulated to reveal putative monomethylarsonate binding sites on the enzyme. The major binding site is in the active site, adjacent to the glutathione binding site. Based on this and previously reported biochemical data, a reaction mechanism for this enzyme is proposed. Further insights were gained from comparison of the human omega-class GSTs to homologs from a range of animals.

GSTT1 null and rs156697 Polymorphism in GSTO2 Influence the Risk and Therapeutic Outcome of B-Acute Lymphoblastic Leukemia Patients

INTRODUCTION

Glutathione S-transferase (GST) gene deletion or polymorphic sequence variations lead to decreased enzyme activity that influences susceptibility and response to chemotherapy in acute lymphoblastic leukemia (ALL). This case-control study investigated the association of GST gene polymorphisms with the etiology and therapeutic outcome of B-ALL among Kashmiri population.

METHODS

A total of 300 individuals including 150 newly diagnosed B-ALL patients and an equal number of age and gender matched controls were genotyped for five GST gene polymorphisms by polymerase chain reaction-restriction fragment length polymorphism technique (PCR-RFLP) and multiplex PCR techniques.

RESULTS

Higher frequency of GSTT1 null, GSTO2-AG, and GSTO2-GG genotypes was observed in ALL cases compared to controls that associated significantly with ALL risk (GSTT1 null: OR = 2.93, p = 0.0001; GSTO2-AG: OR = 2.58, p = 0.01; GSTO2-GG: OR = 3.13, p = 0.01). GSTM1, GSTP1, and GSTO1 SNPs showed no significant association (p > 0.05). Combined genotype analysis revealed significant association of GSTT1 null/GSTM1 null (OR = 4.11, p = 0.011) and GSTT1 null/GSTP1-AG (OR = 4.93, p = 0.0003) with B-ALL susceptibility. Haplotype analysis of rs4925 and rs156697 revealed that carriers of CG haplotype had increased risk of B-ALL (p = 0.04). Kaplan-Meier plots revealed significantly inferior 3-year disease-free survival for GSTO2-GG carriers (p = 0.002). Multivariate analysis confirmed GSTO2-GG as an independent poor prognostic factor for DFS (HR = 4.5, p = 0.034). Among combined genotypes, only GSTT1 null/GSTP1-AG associated significantly with poorer DFS rates (p = 0.032).

CONCLUSION

This study demonstrated that GSTT1 null individually or in combination with GSTM1null and GSTP1-AG genotypes associated with increased B-ALL risk. Also, rs156697 variant genotypes (AG and GG) associated with B-ALL, whereas the GG genotype of rs156697 influenced the treatment outcome.

ASC deglutathionylation is a checkpoint for NLRP3 inflammasome activation

Activation of NLRP3 inflammasome is precisely controlled to avoid excessive activation. Although multiple molecules regulating NLRP3 inflammasome activation have been revealed, the checkpoints governing NLRP3 inflammasome activation remain elusive. Here, we show that activation of NLRP3 inflammasome is governed by GSTO1-promoted ASC deglutathionylation in macrophages. Glutathionylation of ASC inhibits ASC oligomerization and thus represses activation of NLRP3 inflammasome in macrophages, unless GSTO1 binds ASC and deglutathionylates ASC at ER, under control of mitochondrial ROS and triacylglyceride synthesis. In macrophages expressing ASCC171A, a mutant ASC without glutathionylation site, activation of NLRP3 inflammasome is GSTO1 independent, ROS independent, and signal 2 less dependent. Moreover, AscC171A mice exhibit NLRP3-dependent hyperinflammation in vivo. Our results demonstrate that glutathionylation of ASC represses NLRP3 inflammasome activation, and GSTO1-promoted ASC deglutathionylation at ER, under metabolic control, is a checkpoint for activating NLRP3 inflammasome.

Expression profile of a novel glutathione S-transferase gene in the marine polychaete Perinereis aibuhitensis in short-term responses to phenanthrene, fluoranthene, and benzo[α]pyrene

Polychaete worms can eliminate polycyclic aromatic hydrocarbons (PAHs) in environments through a mechanism that increases their water solubility. This detoxification starts with cytochrome P450 enzymes (CYPs) and then with glutathione S-transferases (GSTs). Here, a novel GST gene was identified and characterized from the widespread polychaete Perinereis aibuhitensis. The full-length cDNA of GST is 1544 bp and encodes 256 amino acids, belonging to the omega class. Gene expression patterns in P. aibuhitensis showed that its transcriptional level was positively correlated with the concentration of benzo[α]pyrene (0.5, 2, 4, and 8 μg/L) exposure but was negatively correlated with a PAH benzene ring after it was exposed to the same mass concentrations of fluoranthene (3.2 μg/L), phenanthrene (2.9 μg/L), and benzo[α]pyrene (4.0 μg/L) during the 14-day experimentation. These findings indicate that omega GST may play an important role in the phase II detoxification of PAHs in polychaete worms, and the persistence and bioavailability of PAHs may depend on benzene rings.

Omega-Class Glutathione Transferases of Carcinogenic Liver Fluke, Clonorchis sinensis, Modulate Apoptosis and Differentiation of Host Cholangiocytes

The small liver fluke Clonorchis sinensis causes hepatobiliary ductal infections in humans. Clonorchiasis is characterized histopathologically by ductal dysplasia, hyperplasia and metaplasia, which closely resembles cholangiocarcinoma (CCA). The disruption of programmed cell death is critical for malignant transformation, while molecular events underlying these phenomena have poorly been understood in clonorchiasis-related CCA tumorigenesis. We incorporated recombinant C. sinensis omega-class glutathione transferase (rCsGSTo) 1 or 2 into human intrahepatic biliary epithelial cells (HIBECs) and analyzed pathophysiological alterations of HIBECs upon the application of oxidative stress. rCsGSTos partially but significantly rescued HIBECs from cell death by inhibiting oxidative stress-induced apoptosis (p < 0.01). rCsGSTos modulated transcriptional levels of numerous genes. We analyzed 13 genes involved in programmed cell death (the upregulation of five antiapoptotic and two apoptotic genes, and the downregulation of one antiapoptotic and five apoptotic genes) and 11 genes associated with cell differentiation (the increase in seven and decrease in four genes) that showed significant modifications (p < 0.05). The induction profiles of the mRNA and proteins of these differentially regulated genes correlated well with each other, and mostly favored apoptotic suppression and/or cell differentiation. We detected increased active, phosphorylated forms of Src, PI3K/Akt, NF-κB p65, MKK3/6 and p38 MAPK, but not JNK and ERK1/2. CsGSTos were localized in the C. sinensis-infected rat cholangiocytes, where cytokeratin 19 was distributed. Our results demonstrated that CsGSTos excreted to the biliary lumen are internalized and accumulated in the host cholangiocytes. When cholangiocytes underwent oxidative stressful condition, CsGSTos appeared to be critically involved in both antiapoptotic process and the differentiation of host cholangiocytes through the regulation of target genes following the activation of responsible signal molecules.

Glutathione S-transferases and their implications in the lung diseases asthma and chronic obstructive pulmonary disease: Early life susceptibility?

Our lungs are exposed daily to airborne pollutants, particulate matter, pathogens as well as lung allergens and irritants. Exposure to these substances can lead to inflammatory responses and may induce endogenous oxidant production, which can cause chronic inflammation, tissue damage and remodeling. Notably, the development of asthma and Chronic Obstructive Pulmonary Disease (COPD) is linked to the aforementioned irritants. Some inhaled foreign chemical compounds are rapidly absorbed and processed by phase I and II enzyme systems critical in the detoxification of xenobiotics including the glutathione-conjugating enzymes Glutathione S-transferases (GSTs). GSTs, and in particular genetic variants of GSTs that alter their activities, have been found to be implicated in the susceptibility to and progression of these lung diseases. Beyond their roles in phase II metabolism, evidence suggests that GSTs are also important mediators of normal lung growth. Therefore, the contribution of GSTs to the development of lung diseases in adults may already start in utero, and continues through infancy, childhood, and adult life. GSTs are also known to scavenge oxidants and affect signaling pathways by protein-protein interaction. Moreover, GSTs regulate reversible oxidative post-translational modifications of proteins, known as protein S-glutathionylation. Therefore, GSTs display an array of functions that impact the pathogenesis of asthma and COPD.

In this review we will provide an overview of the specific functions of each class of mammalian cytosolic GSTs. This is followed by a comprehensive analysis of their expression profiles in the lung in healthy subjects, as well as alterations that have been described in (epithelial cells of) asthmatics and COPD patients. Particular emphasis is placed on the emerging evidence of the regulatory properties of GSTs beyond detoxification and their contribution to (un)healthy lungs throughout life. By providing a more thorough understanding, tailored therapeutic strategies can be designed to affect specific functions of particular GSTs.

Glutathione S-Transferases in Cancer

In humans, the glutathione S-transferases (GST) protein family is composed of seven members that present remarkable structural similarity and some degree of overlapping functionalities. GST proteins are crucial antioxidant enzymes that regulate stress-induced signaling pathways. Interestingly, overactive GST proteins are a frequent feature of many human cancers. Recent evidence has revealed that the biology of most GST proteins is complex and multifaceted and that these proteins actively participate in tumorigenic processes such as cell survival, cell proliferation, and drug resistance. Structural and pharmacological studies have identified various GST inhibitors, and these molecules have progressed to clinical trials for the treatment of cancer and other diseases. In this review, we discuss recent findings in GST protein biology and their roles in cancer development, their contribution in chemoresistance, and the development of GST inhibitors for cancer treatment.

Characterization of glutathione S-transferase enzymes in Dictyostelium discoideum suggests a functional role for the GSTA2 isozyme in cell proliferation and development

In this report, we extend our previous characterization of Dictyostelium discoideum glutathione S-transferase (DdGST) enzymes that are expressed in the eukaryotic model organism. Transcript profiling of gstA1-gstA5 (alpha class) genes in vegetative, log phase cells identified gstA2 and gstA3 with highest expression (6-7.5-fold, respectively) when compared to other gstA transcripts. Marked reductions in all gstA transcripts occurred under starvation conditions, with gstA2 and gstA3 exhibiting the largest decreases (-96% and -86.6%, respectively). When compared to their pre-starvation levels, there was also a 60 percent reduction in total GST activity. Glutathione (GSH) pull-down assay and mass spectroscopy detected three isozymes (DdGSTA1, DdGSTA2 and DdGSTA3) that were predominantly expressed in vegetative cells. Biochemical and kinetic comparisons between rDdGSTA2 and rDdGSTA3 shows higher activity of rDdGSTA2 to the CDNB (1-chloro-2,4-dinitrobenzene) substrate. RNAi-mediated knockdown of endogenous DdGSTA2 caused a 60 percent reduction in proliferation, delayed development, and altered morphogenesis of fruiting bodies, whereas overexpression of rDdGSTA2 enzyme had no effect. These findings corroborate previous studies that implicate a role for phase II GST enzymes in cell proliferation, homeostasis, and development in eukaryotic cells.

19-(Benzyloxy)-19-oxojolkinolide B (19-BJB), an ent-abietane diterpene diepoxide, inhibits the growth of bladder cancer T24 cells through DNA damage

Diterpenoids jolkinolide A and B, were first isolated from Euphorbia fischeriana. In our previous research, 19-(Benzyloxy)-19-oxojolkinolide B (19-BJB), a derivative of jolkinolides, was synthesized as a novel ent -abietane diterpene diepoxide. In this study, 19-BJB showed strong in vitro activity against bladder cancer cell lines. DNA damage which was observed through the interaction of 19-BJB with nucleotide chains and affected DNA repair resulted in the activation of checkpoint kinase 1 (Chk1) and checkpoint kinase 2 (Chk2) in bladder cancer cell lines. In vivo testing in nude mice also proved that 19-BJB revealed a potential inhibitory effect on tumor growth. Additionally, the 3D-QSAR models of jolkinolides were established. Briefly, we proved that 19-BJB could potentially be used as a drug to inhibit the growth of bladder tumor.

Changes in Glutathione Content in Liver Diseases: An Update

Glutathione (GSH), a tripeptide particularly concentrated in the liver, is the most important thiol reducing agent involved in the modulation of redox processes. It has also been demonstrated that GSH cannot be considered only as a mere free radical scavenger but that it takes part in the network governing the choice between survival, necrosis and apoptosis as well as in altering the function of signal transduction and transcription factor molecules. The purpose of the present review is to provide an overview on the molecular biology of the GSH system; therefore, GSH synthesis, metabolism and regulation will be reviewed. The multiple GSH functions will be described, as well as the importance of GSH compartmentalization into distinct subcellular pools and inter-organ transfer. Furthermore, we will highlight the close relationship existing between GSH content and the pathogenesis of liver disease, such as non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), chronic cholestatic injury, ischemia/reperfusion damage, hepatitis C virus (HCV), hepatitis B virus (HBV) and hepatocellular carcinoma. Finally, the potential therapeutic benefits of GSH and GSH-related medications, will be described for each liver disorder taken into account.

Airways glutathione S-transferase omega-1 and its A140D polymorphism are associated with severity of inflammation and respiratory dysfunction in cystic fibrosis

BACKGROUND

Glutathione S-transferase omega-1 (GSTO1-1) is a cytosolic enzyme that modulates the S-thiolation status of intracellular factors involved in cancer cell survival or in the inflammatory response. Studies focusing on chronic obstructive pulmonary disease (COPD) have demonstrated that GSTO1-1 is detectable in alveolar macrophages, airway epithelium and in the extracellular compartment, where its functions have not been completely understood. Moreover GSTO1-1 polymorphisms have been associated with an increased risk to develop COPD. Against this background, the aim of this study was to evaluate GSTO1-1 levels and its polymorphisms in cystic fibrosis (CF) patients.

METHODS

Clinical samples from a previous study published by our groups were analyzed for GSTO1-1 levels and polymorphisms. For comparison, a model of lung inflammation in CFTR-knock out mice was also used.

RESULTS

Our data document that soluble GSTO1-1 can be found in the airways of CF patients and correlates with inflammatory parameters such as neutrophilic elastase and the chemokine IL-8. A negative correlation was found between GSTO1-1 levels and the spirometric parameter FEV1 and the FEV1/FVC ratio. Additionally, the A140D polymorphism of GSTO1-1 was associated with lower levels of the antiinflammatory mediators PGE2 and 15(S)-HETE, and with lower values of the FEV1/FVC ratio in CF subjects with the homozygous CFTR ΔF508 mutation.

CONCLUSIONS

Our data suggest that extracellular GSTO1-1 and its polymorphysms could have a biological and clinical significance in CF. Pathophysiological functions of GSTOs are far from being completely understood, and more studies are required to understand the role(s) of extracellular GSTO1-1 in inflamed tissues.

Discovery of 6-(7-Nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol Derivatives as Glutathione Transferase Inhibitors with Favorable Selectivity and Tolerated Toxicity

Glutathione transferase (GST P1-1) is a potential target for anticancer drugs. In this work, a series of 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol (NBDHEX) derivatives as GST P1-1 inhibitors were designed, synthesized, and evaluated for their biological activity. Among the target compounds, 4n showed more selective inhibition toward GST P1-1 and GST M2-2, better water solubility, and more potent anticancer activities toward all the tested cancer cells (except for HOS) than its parent molecule. Detailed biological studies on the effect of 4n toward 143b cells revealed that 4n could arrest the cell cycle at the G2 phase and induced cell apoptosis in a dose-dependent manner. Like NBDHEX, 4n displayed good pharmacokinetic characteristics. An in vivo study on 143b xenograft models demonstrated that 4n could significantly reduce tumor growth in a dose-dependent manner, showing stronger antitumor activity than NBDHEX. Thus, 4n deserves to be further investigated as a potential antitumor agent for cancer therapy.

Molecular characterization, immune and xenobiotic responses of glutathione S-transferase omega 1 from the big-belly seahorse: Novel insights into antiviral defense

Glutathione S-transferases (GSTs) are important enzymes involved in phase II detoxification and function by conjugating with the thiol group of glutathione. In this study, we isolated an omega class GST from the big-belly seahorse (Hippocampus abdominalis; HaGSTO1) to study the putative xenobiotic responses and defense ability against viral and bacterial infections in this animal. The isolated HaGSTO1 gene, with a cording sequence of 720 bp, encodes a peptide of 239 amino acids. The predicted molecular mass and theoretical isoelectric point of HaGSTO1 was 27.47 kDa and 8.13, respectively. In-silico analysis of HaGSTO1 revealed a characteristic N-terminal thioredoxin-like domain and a C-terminal domain. Unlike other GSTs, the C-terminal of HaGSTO1 reached up to the N-terminal, and the N-terminal functional group was cysteine rather than tyrosine or serine, as observed in other GSTs. Phylogenetic analysis showed the evolutionary proximity of HaGSTO1 with other identified vertebrate and invertebrate GST orthologs. For the first time, we demonstrated the viral defense capability of HaGSTO1 against viral hemorrhagic septicemia virus (VHSV) infection. All six nucleoproteins of VHSV were significantly downregulated in HaGSTO1-overexpressing FHM cells at 24 h after infection compared with those in the control. Moreover, arsenic toxicity was significantly reduced in HaGSTO1-overexpressing FHM cells, and cell viability increased. Real-time polymerase chain reaction analysis showed that HaGSTO1 transcripts were highly expressed in the pouch and gill when compared with those in other tissues. Blood HaGSTO1 transcripts were significantly upregulated after Edwardsiella tarda, Streptococcus iniae, lipopolysaccharide, and polyinosinic:polycytidylic acid challenge experiments. Collectively, these findings suggest the involvement of HaGSTO1 in the host defense mechanism of seahorses.

Upregulated microRNA-423-5p promotes oxidative stress through targeting glutathione S-transferase mu 1 in asthenozoospermia

The dysregulation of microRNAs (miRNAs) plays an important role in asthenozoospermia. This study evaluated the sperm microRNA-423-5p (miR-423-5p) expression in asthenozoospermia and normozoospermia, exploring the role of miR-423-5p in asthenozoospermia. Eighty participants were divided into asthenozoospermic (AZS, n = 40) and normozoospermic (Norm, n = 40) groups. Fresh semen samples were collected and the sperm cells were separated. Quantitative Real-Time polymerase chain reaction was used to measure the sperm miR-423-5p level. Receiver operating characteristic curve (ROC) was employed to test the diagnostic performance of miR-423-5p in asthenospermia. Dual-reporter luciferase assay was adopted to confirm the target gene of miR-423-5p. The target gene level in asthenozoospermia and normozoospermia was measured, and the biological function of target gene in asthenozoospermia was evaluated. Results showed that the miR-423-5p expression level in the AZS group was higher than that in Norm group, which was positively correlated with the severity of asthenozoospermia. ROC analysis of miR-423-5p showed an area under curve (AUC) of 0.69 (95% confidence interval = 0.57-0.80, p <0 .01), with 80% sensitivity and 60% specificity. Glutathione S-transferase mu 1 (GSTM1) is a target gene of miR-423-5p, which significantly decreased in the AZS group. Compared with Norm group, glutathione S-transferase (GST) activity and total antioxidant capacity (TAC) level decreased, while malondialdehyde (MDA) level increased in the AZS group. Furthermore, GST activity and TAC level were negatively correlated with miR-423-5p expression, while MDA level was positively correlated with miR-423-5p expression. In conclusion, the sperm miR-423-5p level significantly was upregulated in asthenozoospermia. High-level miR-423-5p inhibited sperm motility through targeting GSTM1 to promote oxidative stress.

Diversity of Omega Glutathione Transferases in mushroom-forming fungi revealed by phylogenetic, transcriptomic, biochemical and structural approaches

The Omega class of glutathione transferases (GSTs) forms a distinct class within the cytosolic GST superfamily because most of them possess a catalytic cysteine residue. The human GST Omega 1 isoform was first characterized twenty years ago, but it took years of work to clarify the roles of the human isoforms. Concerning the kingdom of fungi, little is known about the cellular functions of Omega glutathione transferases (GSTOs), although they are widely represented in some of these organisms. In this study, we re-assess the phylogeny and the classification of GSTOs based on 240 genomes of mushroom-forming fungi (Agaricomycetes). We observe that the number of GSTOs is not only extended in the order of Polyporales but also in other orders such as Boletales. Our analysis leads to a new classification in which the fungal GSTOs are divided into two Types A and B. The catalytic residue of Type-A is either cysteine or serine, while that of Type-B is cysteine. The present study focuses on Trametes versicolor GSTO isoforms that possess a catalytic cysteine residue. Transcriptomic data show that Type-A GSTOs are constitutive enzymes while Type-B are inducible ones. The crystallographic analysis reveals substantial structural differences between the two types while they have similar biochemical profiles in the tested conditions. Additionally, these enzymes have the ability to bind antioxidant molecules such as wood polyphenols in two possible binding sites as observed from X-ray structures. The multiplication of GSTOs could allow fungal organisms to adapt more easily to new environments.

Responses of cytochrome P450, GST and MXR in the mussel Perna viridis to the exposure of Aureococcus anophagefferens

The brown tide formed by a microscopic alga called Aureococcus anophagefferens has a devastating effect on filter-feeding bivalves, however, the related toxic principle remains an open question. In this study, we found that A. anophagefferens cells could motivate detoxification associated genes including CYP450, GST, P-gp and MVP, and induce SOD activity in the mussel Perna viridis. D1-like and D2-like receptors were expressed at high level in the gills of P. viridis, however, D2-like receptor transcript was too low to detect in digestive gland. The exposure of A. anophagefferens did not lead to any significant alterations in the expression of D1-like and D2-like receptors in both gills and digestive gland. These findings suggested that A. anophagefferens exhibited cytotoxicity toward bivalves, but did not obviously disrupt the dopamine system at transcriptional level in the acute exposure. Further studies are warranted to explore the nature of toxic compounds in A. anophagefferens affected bivalves.