Inhibition Of Glutathione S-transferase Research Articles

A glutathione S-transferase and a cytochrome P450 may confer cyhalofop-butyl resistance in Leptochloa chinensis (L.) Nees

BackgroundLeptochloa chinensis (L.) Nees is a troublesome weed across China in rice fields, and a suspected L. chinensis resistant population (R) that has survived the recommended field dose of cyhalofop-butyl was collected in a rice field of Hunan Province, China. In this study, we aimed to determine the acetyl-CoA carboxylase-inhibiting herbicide resistance profile of this R population and to investigate its mechanisms of resistance to cyhalofop-butyl. ResultsCompared with the susceptible population (S), the R population was confirmed to be 18.9-, 3.2-, 4.1-, 3.6- and 5.8- fold resistant to the APP herbicides cyhalofop-butyl, haloxyfop-P-methyl, clodinafop-propargyl, metamifop and fenoxaprop-P-ethyl, respectively. ACCase gene sequencing analysis revealed no known resistance mutations for TSR in the R population. Pretreatment with the glutathione S-transferase (GST) inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) and cytochrome P450 (CYP450) inhibitor malathion reversed resistance to cyhalofop-butyl. The GST gene GSTU1 and CYP450 gene CYP707A5 were constitutively upregulated in the R population according to RNA-seq analysis and RT-qPCR verification. The molecular docking results indicated a good affinity of the active site for five APP herbicides with GSTU1 and CYP707A5. ConclusionThis study shows that the GSTU1 and CYP707A5 genes expressed highly in the R population may be responsible for cyhalofop-butyl resistance in L. chinensis.

Overexpression of Glutathione S-Transferases in Human Diseases: Drug Targets and Therapeutic Implications.

Glutathione S-transferases (GSTs) are a major class of phase II metabolic enzymes. Besides their essential role in detoxification, GSTs also exert diverse biological activities in the occurrence and development of various diseases. In the past few decades, much research interest has been paid to exploring the mechanisms of GST overexpression in tumor drug resistance. Correspondingly, many GST inhibitors have been developed and applied, solely or in combination with chemotherapeutic drugs, for the treatment of multi-drug resistant tumors. Moreover, novel roles of GSTs in other diseases, such as pulmonary fibrosis and neurodegenerative diseases, have been recognized in recent years, although the exact regulatory mechanisms remain to be elucidated. This review, firstly summarizes the roles of GSTs and their overexpression in the above-mentioned diseases with emphasis on the modulation of cell signaling pathways and protein functions. Secondly, specific GST inhibitors currently in pre-clinical development and in clinical stages are inventoried. Lastly, applications of GST inhibitors in targeting cell signaling pathways and intracellular biological processes are discussed, and the potential for disease treatment is prospected. Taken together, this review is expected to provide new insights into the interconnection between GST overexpression and human diseases, which may assist future drug discovery targeting GSTs.

Feedback enhanced tumor targeting delivery of albumin-based nanomedicine to amplify photodynamic therapy by regulating AMPK signaling and inhibiting GSTs

Oxidative therapies receive a limited antitumor efficiency due to the insufficient reactive oxygen species (ROS) levels at focal sites and the evolvement of antioxidant defense systems. Herein, we develop an albumin-based nanomedicine to co-deliver chlorin e6 (Ce6) and COH-SR4 (CS), which can simultaneously enhance the yield and lethality of intracellular ROS for amplified photodynamic therapy (PDT). In which, CS acts as both an activator of AMP-activated protein kinase (AMPK) and an inhibitor of glutathione S-transferases (GSTs). Benefiting from it, the prepared HSA-Ce6@COH-SR4 (HCCS) enables positive feedback uptake by promoting AMPK phosphorylation, leading to rapid and extensive tumor accumulation of drugs. As a result, HCCS obviously increases the ROS production to elevate intracellular oxidative stress. Furthermore, HCCS can inhibit GSTs to disturb the antioxidant defense system of tumor cells, intensifying the oxidative damage of ROS. Ultimately, the PDT of HCCS is significantly strengthened by improving the ROS yield and lethality, which greatly declines the proliferation of breast cancer in vivo. This study may open a window in the development of drug co-delivery system for enhanced oxidative therapy of tumors.

A dual-acting aldose reductase inhibitor impedes oxidative and carbonyl stress in tissues of fructose- and streptozotocin-induced rats: comparison with antioxidant stobadine

Inhibiting aldose reductase (ALR2, AR) as well as maintaining a concomitant antioxidant (AO) activity via dual-acting agents may be a rational approach to prevent cellular glucotoxicity and at least delay the progression of diabetes mellitus (DM). This study was aimed at evaluating the dual-acting AR inhibitor (ARI) cemtirestat (CMTI) on tissue oxidative stress (OS) and carbonyl stress (CS) biomarkers in rats exposed to fructose alone (F) or fructose plus streptozotocin (D; type-2 diabetic). D and F rats were either untreated or treated daily with low- or high-dose CMTI, ARI drug epalrestat (EPA) or antioxidant stobadine (STB) for 14 weeks. Malondialdehyde (MDA), glutathione S-transferase (GST), nitric oxide synthase (NOS), and catalase (CAT) were increased in the sciatic nerve of F and D. These increases were attenuated by low doses of CMTI and STB in D, but exacerbated by low-dose EPA and high-dose CMTI in F. STB and CMTI and to a lesser extent EPA improved MDA, protein-carbonyl, GST and CAT in the hearts and lungs of F and D. CMTI and STB were more effective than EPA in improving the increased MDA and protein-carbonyl levels in the kidneys of F and especially D. CMTI ameliorated renal GST inhibition in D. In the lungs, hearts, and kidneys of F and D, the GSH to GSSG ratio decreased and caspase-3 activity increased, but partially resolved with treatments. In conclusion, CMTI with ARI/AO activity may be advantageous in overcoming OS, CS, and their undesirable consequences, with low dose efficacy and limited toxicity, compared to ARI or antioxidant alone.

Eleusine indica Cytochrome P450 and Glutathione S-Transferase Are Linked to High-Level Resistance to Glufosinate.

Eleusine indica has become a global nuisance weed and has evolved resistance to glufosinate. The involvement of target-site resistance (TSR) in glufosinate resistance in E. indica has been elucidated, while the role of nontarget-site resistance (NTSR) remains unclear. Here, we identified a glufosinate-resistant (R) population that is highly resistant to glufosinate, with a resistance index of 13.5-fold. Molecular analysis indicated that the resistance mechanism of this R population does not involve TSR. In addition, pretreatment with two known metabolic enzyme inhibitors, the cytochrome P450 (CYP450) inhibitor malathion and the glutathione S-transferase (GST) inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl), increased the sensitivity of the R population to glufosinate. The results of subsequent RNA sequencing (RNA-seq) and quantitative real-time PCR (RT-qPCR) suggested that the constitutive overexpression of a GST gene (GSTU3) and three CYP450 genes (CYP94s and CYP71) may play an important role in glufosinate resistance. This study provides new insights into the resistance mechanism of E. indica.

Arylcoumarin and novel biscoumarin derivatives as potent inhibitors of human glutathione S-transferase

A series of arylcoumarin derivatives and two novel biscoumarin derivatives were investigated for their human recombinant glutathione S-transferase P1-1 (GSTP1-1) enzyme inhibitory activities for the first time. 4-(3,4-Dihydroxyphenyl)-6,7-dihydroxycoumarin (compound 24) was observed to be the most active coumarin derivative (IC50: 0.14 µM). The inhibition was found to be time-dependent and irreversible. Hypothetical binding modes of the ten most active compounds were calculated by molecular docking. Ligand efficiency indices (LEI) were estimated to better understand the binding performance of the coumarin derivatives. Extensive structure-activity relationship studies showed that hydroxy substitution on both the coumarin and the aryl ring enhanced the biological activity and the position of hydroxy group on the coumarin ring is critical for the binding pose and the activity. Top three ligands were subjected to molecular dynamics simulations and MM/PBSA for further investigation. Binding mode of compound 24 suggested that its high inhibitory activity might be attributed to its position between Tyr7 and the cofactor, glutathione (GS-DNB). Exhibiting favorable druglikeness profiles and pharmacokinetics based on ADME studies, compound 5 and 24 can be considered as potential drug leads in future studies for further development. Communicated by Ramaswamy H. Sarma

Busulfan induces steatosis in HepaRG cells but not in primary human hepatocytes: Possible explanations and implication for the prediction of drug-induced liver injury.

The antineoplastic drug busulfan can induce different hepatic lesions including cholestasis and sinusoidal obstruction syndrome. However, hepatic steatosis has never been reported in patients. This study aimed to determine whether busulfan could induce steatosis in primary human hepatocytes (PHH) and differentiated HepaRG cells. Neutral lipids were determined in PHH and HepaRG cells. Mechanistic investigations were performed in HepaRG cells by measuring metabolic fluxes linked to lipid homeostasis, reduced glutathione (GSH) levels, and expression of genes involved in lipid metabolism and endoplasmic reticulum (ER) stress. Analysis of two previous transcriptomic datasets was carried out. Busulfan induced lipid accumulation in HepaRG cells but not in six different batches of PHH. In HepaRG cells, busulfan impaired VLDL secretion, increased fatty acid uptake, and induced ER stress. Transcriptomic data analysis and decreased GSH levels suggested that busulfan-induced steatosis might be linked to the high expression of glutathione S-transferase (GST) isoenzyme A1, which is responsible for the formation of the hepatotoxic sulfonium cation conjugate. In keeping with this, the GST inhibitor ethacrynic acid and the chemical chaperone tauroursodeoxycholic acid alleviated busulfan-induced lipid accumulation in HepaRG cells supporting the role of the sulfonium cation conjugate and ER stress in steatosis. While the HepaRG cell line is an invaluable tool for pharmacotoxicological studies, it might not be always an appropriate model to predict and mechanistically investigate drug-induced liver injury. Hence, we recommend carrying out toxicological investigations in both HepaRG cells and PHH to avoid drawing wrong conclusions on the potential hepatotoxicity of drugs and other xenobiotics.

Can the Herbicide Dicamba Produce Oxidative Stress in the Native South American fish Jenynsia lineata at Environmentally Relevant Concentrations?

Dicamba (DIC) is one of the most applied auxin herbicides worldwide. Sublethal effects in the South American native fish Jenynsia lineata exposed to DIC concentrations close to environmental concentrations (0.03-30µg/L) during 48h were analysed thorough the evaluation of catalase (CAT), glutathione S-transferase (GST), superoxide dismutase (SOD) activities and malondialdehyde (MDA) and H2O2 levels for detecting potential oxidative stress. In gills MDA increased showing oxidative damage probably because of an inefficient antioxidant defense. This response evidenced the important role of gills as an organ of direct contact with waterborne contaminants. In addition, other changes in the biomarkers of oxidative stress were observed such as the inhibition of SOD activities in brain and the inhibition of GST in liver. These results show that short- term exposures to environmentally relevant concentrations of DIC could induce sublethal effects in native fish.

Phytochemical analysis and biological activity of Corchorus olitorius L.: Quantitative analysis of bioactive compounds by LC–MS/MS, antibacterial, enzyme inhibition, and cytotoxic activities

IntroductionCorchorus olitorius L. is a significant plant in folk medicine, therefore, research on phytochemistry with biological activity may reveal its potential use in drug development. Medicinal plants are valuable sources of drug materials as they include bioactive compounds known as secondary metabolites. Determination of bioactive compounds and biological activity of plants lead to understanding their potential in drug development. MethodsA quantitative analysis of the bioactive compounds in leaf, stem, and root extracts of C. olitorius L. was carried out with Liquid Chromatography-Mass Spectrometry (LC–MS/MS). Acetylcholinesterase (AChE) and Glutathione-S-Transferase (GST) enzyme inhibition and antibacterial effects were investigated using Mueller Hinton broth microdilution assay. The anticancer activity of C. olitorius leaves was evaluated by MTT assay using HDF, U87, Skov-3, and Caco-2 cell lines. ResultsIn the quantitative study, leaf extract exhibited the largest concentration of bioactive compounds, and cynarin (6.680 mg/g extract) and chlorogenic acid (5.605 mg/g extract) were the major products. The leaf, stem, and root extracts showed significant AChE and GST inhibition activity. The leaf extract displayed antibacterial activity against P. aeruginosa with the value of 2.2±0.1 (IC50, μg/ mL) in comparison to the standard (4.00±0.1 IC50, μg/ mL). The leaf extract displayed good antiproliferative activity against sk-ov-3 cell lines with values of 37.1% and 42.1% at 250 μg/mL and 500 μg/mL concentrations, respectively. ConclusionC. olitorius has the potential to be a drug agent against cancer and microbial-induced diseases due to its effective bioactive compound contents.

Discovery, SAR Study of GST Inhibitors from a Novel Quinazolin-4(1H)-one Focused DNA-Encoded Library.

The DNA-encoded library (DEL) is a powerful hit-generation tool in drug discovery. This study describes a new DEL with a privileged scaffold quinazolin-4(3H)-one developed by a robust DNA-compatible multicomponent reaction and a series of novel glutathione S-transferase (GST) inhibitors that were identified through affinity-mediated DEL selection. A novel inhibitor 16 was subsequently verified with an inhibitory potency value of 1.55 ± 0.02 μM against SjGST and 2.02 ± 0.20 μM against hGSTM2. Further optimization was carried out via various structure-activity relationship studies. And especially, the co-crystal structure of the compound 16 with the SjGST was unveiled, which clearly demonstrated its binding mode was quite different from the known GSH-like compounds. This new type of probe is likely to play a different role compared with the GSH, which may provide new opportunities to discover more potent GST inhibitors.

Novel Mannich bases derived from 1,2,4-triazoles: Design, synthesis, characterization, and glutathione S-transferase inhibition properties investigations

The reaction of variously substituted 1,2,4-triazole derivatives with morpholine and formaldehyde represents an efficient and easy-to-set synthetic entry toward heterocyclic N-Mannich bases. For this purpose, the synthesized Schiff Bases (3a-g) were reacted with formaldehyde and morpholine, a secondary amine, to yield novel N-Mannich bases (6a-g). The structures of the compounds (6a-g) were determined structurally by employing 1H/13C-NMR, IR, and elemental analysis. The synthesized compounds were screened for in vitro biological activity, and the bioanalysis results showed that the newly synthesized compounds had different in vitro enzyme inhibition activities against Glutathione S-transferase (GST). Their Ki values were calculated in the 2.69 ± 0.421–21.58±6.809 µM range. Besides, their IC50 values were calculated in the 1.975–2.753 µM range. Also, the potential inhibitory effects of the synthesized compounds on glutathione S-transferase enzyme were evaluated by in silico method. The highest affinity values for inhibition of glutathione S-transferase enzyme were observed as 6c (−7.7 kcal/mol), 6 g (−7.4 kcal/mol), and 6b (−6.8 kcal/mol), respectively, and they gave better affinity values than standard Ethacrynic acid. Furthermore, the absorption distribution, metabolism, and excretion properties (ADME), molecular properties, toxicity estimation, and compounds' bioactivity scores were evaluated.

Nanosilica size-dependent toxicity in Ceriodaphnia reticulata (Cladocera)

Silica nanoparticles (SiNP) are the most produced nanomaterials due to their variety of applications. When released to environments, surface water bodies are their main final sink. SiNP toxicity is still inconclusive and may vary according to particle properties such as their size. We analyzed the size-related effects of SiNP (22 and 244 nm) on mortality, life history traits, and oxidative stress in the cladoceran Ceriodaphnia reticulata. The smaller SiNP (LC5072 h: 105.5 µg/ml) were more lethal than the larger ones (LC5072 h >500 µg/ml). The 22 nm-sized SiNP decreased the number of molts and neonates, increased superoxide dismutase and inhibited glutathione S-transferase activities, while larger SiNP did not exert substantial effects on the organisms at the tested concentrations. In conclusion, SiNP toxicity depended on their size, and this information should be considered for regulatory purposes and to the development of safe-by-design nanoproducts to ultimately guarantee the environment protection.

Assessment of Colocasia esculenta leaf extract as a natural alternative for Sitophilus zeamais control: Toxicological, biochemical, and mechanistic insights

The present study assessed the toxicological, biochemical, and mechanism of action of Colocasia esculenta leaf extract (CELE) on Wistar albino rat and on cholinergic, antioxidant, and antiinflammatory enzymes in Sitophilus zeamais. This was with a view to assessing the potential benefits and safety profile of CELE as a natural alternative for insect control. The bioactivity of the fraction was evaluated using insecticidal and repellent activities against colonies of Sitophilus zeamais to obtain a VLC-chromatographed fraction which was spectroscopically characterized and investigated for enzyme inhibition. The results revealed the ethyl acetate fraction (EAF) as the most potent one with LC50 6.198 μg/ml and 6.6 ± 0.5 repellency. The EAF had an LD50 > 5000 mg/kg but repeated dose >800 mg/kgbw po administration caused significant (p < 0.05) increase in liver and kidney function biomarkers accompanied with elevated atherogenic and coronary indices. Also, renal and hepatomorphological lesions increased in a dose–dependent manner. The High-Performance Liquid Chromatography analysis profiled 7 unknown compounds while the GC-qMS revealed 103 compounds in the CC6 fraction allowing for their identification, quantification, and providing insights into the biological activities and its potentials application. The CC6 fraction inhibited glutathione S-transferase (IC50 = 2265.260.60 mg/ml), superoxide dismutase (IC50 = 1485.300.78 mg/ml), catalase (IC50 = 574.471.57 mg/ml), acetyl cholinesterase (IC50 = 838.280.51 mg/ml), butyryl cholinesterase (IC50 = 1641.76 ± 1.14 mg/ml) and upregulated cyclooxygenase-2 (IC50 = 37.89 ± 0.15 mg/ml). Based on the result of the study, it could be inferred that the unidentified compounds present in the EAF exhibit strong insecticidal properties. The study concluded that the acute toxicity of the potent fraction showed no abnormal clinical toxic symptoms while a repeated dose of the extract in sub-acute studies showed a toxic effect that is dose-dependent. The mechanism of action of the purified fraction could be said to be by inhibition of cholinergic and antioxidant enzymes. However, the potent fraction also upregulated the activity of anti-inflammatory enzymes. Hence, regulated amount of CELE at a repeated dose <800 mg/kgbw could be considered for use as an anti-pest agent in Integrated Pest Management of Sitophilus zeamais.

Natural deep eutectic solvents (NADESs) assisted extraction of essential oil from Nardostachys jatamansi (D.Don) DC with insecticidal activities

Different Natural deep eutectic solvents (NADESs) combinations were employed as a cosolvent in the conventional hydro-distillation method for extracting essential oil (EO) from the roots of Nardostachys jatamansi (D.Don) DC. Subsequent enhancement in EO yield along with phytochemical variation was observed on implementing NADESs as an extraction media compared to conventional hydro-distillation method using water. Among different combinations, the highest yield (1.7% v/w) of EO was observed with NADES-5 (choline chloride: maleic acid; 2:1) as compared to the conventional method (0.9% v/w, lowest yield among all combinations). Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analysis of all extracted EOs led to the identification of 34 compounds accounting for 76.13–87.87% of the total area percentage. Principal component analysis (PCA) and clustered heatmaps were used for multivariate analysis showing discrimination of the constituents in different EOs. Valeranone (31.22–12.60%) and nerolidol (21.39–1.82%) were observed in all samples, whereas some molecules like bisabolol, α-cadinol, and nootkatone were specific to certain samples, showing variability in chemical composition. EOs were further examined for their insecticidal and enzyme inhibitory activity against Aphis craccivora Koch (Hemiptera: Aphididae) and Planococcus lilacinus Cockerell (Hemiptera: Pseudococcidae), which are major sucking pests of legumes, vegetables, fruit and plantation crops. Results showed that the EOs obtained with water, NADES-4 (choline chloride: lactic acid; 1:2), 1 (choline chloride: oxalic acid; 1:1), 3 (choline chloride: lactic acid; 1:1), and 6 (glycerol: lactic acid; 1:1) showed promising toxicity (LD50 =0.80–0.98 µL/insect) against A. craccivora. Similarly, EOs obtained with water, NADES-3 (choline chloride: lactic acid; 1:1), and 4 (choline chloride: lactic acid; 1:2) also showed toxicity (LD50 =0.90–1.19 µL/insect) against P. lilacinus, which may be attributed to the presence of high concentration of metabolites such as valeranone, β-patchoulene, nerolidol, α-cadinol and viridiflorol. Further, LD50 concentrations of EO from water showed significant inhibition of glutathione S-transferase (8.52 ± 3.91 and 11.83 ± 5.68 nmol/min/mL) and acetylcholinesterase (0.67 ± 0.04 and 0.75 ± 0.09 mU/mg) after 24 h in A. craccivora and P. lilacinus, respectively.

Target-site mutation and enhanced metabolism endow resistance to nicosulfuron in a Digitaria sanguinalis population

Digitaria sanguinalis is a competitive and annual grass weed that commonly infests crops across the world. In recent years, the control of D. sanguinalis by nicosulfuron has declined in Hebei Province, China. To determine the resistance mechanisms of D. sanguinalis to nicosulfuron, a population of D. sanguinalis where nicosulfuron had failed was collected from a maize field of Hebei Province, China. Whole-plant dose–response experiments demonstrated that the resistant population (HBMT-15) displayed 6.9-fold resistance to nicosulfuron compared with the susceptible population (HBMT-5). Addition of the glutathione S-transferase (GSTs) inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) significantly reduced the resistance level of the HBMT-15 population to nicosulfuron, and the GSTs activity of the HBMT-15 population was higher than the HBMT-5 population after nicosulfuron treatment. In vitro acetolactate synthase (ALS) enzyme experiments revealed that the nicosulfuron I50 value for the HBMT-15 population was 41 times higher than that of the HBMT-5 population. An Asp376 to Glu substitution in the ALS gene was identified in the HBMT-15 population. The HBMT-15 population had a moderate (2- to 4-fold) level of cross-resistance to three other ALS inhibitors (imazethapyr, pyroxsulam, and flucarbazone‑sodium), but was susceptible to pyrithiobac‑sodium. This study demonstrated that both an Asp376 to Glu substitution in the ALS gene and GSTs-involved metabolic resistance to ALS inhibitors coexisted in a D. sanguinalis population.

Evidences of metabolic alterations and cellular damage in different tissues of scallops Aequipecten tehuelchus exposed to cadmium

Scallops Aequipecten tehuelchus (Patagonia, Argentina) were exposed to 0, 2, 5 and 12 μg Cd/L for 7 and 14 days, causing in digestive gland a significant production of reactive oxygen and nitrogen species (RONS), induction of catalase (CAT) and glutathione S-transferase (GST) activities and metallothioneins (MT) synthesis. In gills, there was inhibition of GST and induction of CAT, MT and α-tocopherol (α-Toc). In muscle, a significant increment of MT was also registered and inhibition of CAT. Lipid peroxidation, measured as TBARS, was not promoted in any tissue. More significant effects were observed in digestive gland than in gills and muscle, evidencing the critical role of digestive gland in Cd accumulation and metabolisation. This research would evidence dose-dependent effects of Cd on MT, GST, CAT and α-Toc in the three organs assayed, as well as a time-dependent effect of Cd on the response of CAT, GST and TBARS in digestive gland.

Metabolic Exploration for Cyhalofop-Butyl Antagonism in Barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] Following Pretreatment of Malathion.

The present study investigated the effects of broad-spectrum metabolic inhibitors malathion (cytochrome P450 inhibitor) and/or 4-chloro-7-nitrobenzofurazan (NBD-Cl; glutathione S-transferase inhibitor) on the metabolism of cyhalofop-butyl (CyB) in barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] biotypes confirmed previously with multiple resistance to two herbicides CyB and florpyrauxifen-benzyl. The metabolic inhibitors were not effective at recovering the sensitivity of resistant barnyardgrass biotypes to CyB treated at the labeled rate (313 g ai ha-1). Rather, treatment with malathion followed by CyB caused antagonism, reducing the efficacy of CyB and promoting the growth of resistant biotypes. Pretreatment with malathion did not influence absorption/translocation of the applied form CyB and its conversion to the active herbicide form cyhalofop-acid (CyA), in both susceptible and resistant biotypes. In contrast, metabolism of the applied form (CyB) decreased 1.5 to 10.5 times by the malathion pretreatment. Taken together, the maintained CyA production against the reduced CyB metabolism could be the mechanism to account for the cause of CyB antagonism observed in barnyardgrass following malathion pretreatment. Additionally, the evolution of CyB resistance in barnyardgrass might be associated with reduced production of CyA in resistant biotypes, independent of activities of cytochrome P450 or GST enzymes.

Molecular mechanism of resistance to mesosulfuron-methyl in shortawn foxtail (Alopecurus aequalis) from China

AbstractShortawn foxtail (Alopecurus aequalis Sobol.) is an obligate wetland plant that is widely distributed throughout Europe, temperate Asia, and North America. In China, it is widespread in the middle and lower reaches of the Yangtze River as a noxious weed in winter cropping fields with a rice (Oryza sativa L.) rotation. The acetolactate synthase (ALS)-inhibiting herbicide mesosulfuron-methyl has been widely used to control annual grass and broadleaf weeds, including A. aequalis, in wheat (Triticum aestivum L.) fields, leading to the selection of herbicide-resistant weeds. In this study, an A. aequalis population, AHFT-4, that survived mesosulfuron-methyl at the field-recommended rate (9 g ai ha−1) was collected in Anhui Province. Single-dose testing confirmed that the suspected resistant AHFT-4 had evolved resistance to mesosulfuron-methyl. Target gene sequencing revealed a resistance mutation of Pro-197-Ala in ALS1 of the resistant plants, and a derived cleaved amplified polymorphic sequence marker was developed to specifically detect the mutation. A relative expression assay showed no significant difference in ALS expression between AHFT-4 and a susceptible population without or with mesosulfuron-methyl treatment. Whole-plant dose–response bioassays indicated that AHFT-4 had evolved broad-spectrum cross-resistance to ALS-inhibiting herbicides of all five chemical families tested, with GR50 resistance index (RI) values ranging from 21 to 206. However, it remained susceptible to the photosystem II inhibitor isoproturon. Pretreatment with the cytochrome P450 inhibitor malathion or the glutathione S-transferase inhibitor 4-chloro-7-nitrobenzoxadiazole had no significant effects on the resistance of AHFT-4 to mesosulfuron-methyl. To our knowledge, this study reports for the first time the ALS gene Pro-197-Ala substitution conferring broad-spectrum cross-resistance to ALS-inhibiting herbicides in A. aequalis.

The Multifaceted Role of Glutathione S-Transferases in Health and Disease.

In humans, the cytosolic glutathione S-transferase (GST) family of proteins is encoded by 16 genes presented in seven different classes. GSTs exhibit remarkable structural similarity with some overlapping functionalities. As a primary function, GSTs play a putative role in Phase II metabolism by protecting living cells against a wide variety of toxic molecules by conjugating them with the tripeptide glutathione. This conjugation reaction is extended to forming redox sensitive post-translational modifications on proteins: S-glutathionylation. Apart from these catalytic functions, specific GSTs are involved in the regulation of stress-induced signaling pathways that govern cell proliferation and apoptosis. Recently, studies on the effects of GST genetic polymorphisms on COVID-19 disease development revealed that the individuals with higher numbers of risk-associated genotypes showed higher risk of COVID-19 prevalence and severity. Furthermore, overexpression of GSTs in many tumors is frequently associated with drug resistance phenotypes. These functional properties make these proteins promising targets for therapeutics, and a number of GST inhibitors have progressed in clinical trials for the treatment of cancer and other diseases.

MRNA Sequencing Reveals Upregulation of Glutathione S-Transferase Genes during Acanthamoeba Encystation.

Some members of the genus Acanthamoeba are facultative pathogens typically with a biphasic lifestyle: trophozoites and cysts. Acanthamoeba is capable of infecting the cornea, resulting in Acanthamoeba keratitis. The cyst is one of the key components for the persistence of infection. Gene expression during Acanthamoeba encystation showed an upregulation of glutathione S-transferase (GST) genes and other closely related proteins. mRNA sequencing showed GST, and five genes with similar sequences were upregulated after 24 h of inducing encystation. GST overexpression was verified with qPCR using the HPRT and the cyst-specific protein 21 genes as controls. The GST inhibitor ethacrynic acid was found to decrease cell viability by 70%. These results indicate a role of GST in successful encystation, possibly by maintaining redox balance. GST and associated processes could be targets for potential treatments alongside regular therapies to reduce relapses of Acanthamoeba infection.