Piperonyl butoxide elicits a robust transcriptional response in adult Drosophila melanogaster.

While much attention has been devoted to understanding the transcriptional changes underlying resistance to insecticides, comparatively little is known about the transcriptional response of naive insects to agrochemicals. In this study, we analyze the transcriptomic response of an insecticide susceptible strain of Drosophila melanogaster to nine agrochemicals using a robust method that goes beyond classical replication standards. Our findings demonstrate that exposure to piperonyl butoxide (PBO), but not to eight other compounds, elicits a robust transcriptional response in a wild-type strain of Drosophila melanogaster. PBO exposure leads to the upregulation of a subset of Cyps, GSTs, UGTs and EcKls. This response is both time and concentration-dependent, suggesting that the degree of inhibition of P450 activity correlates with the magnitude of the transcriptional response. Furthermore, the upregulation of these enzymes is excluded from reproductive organs. Additionally, different sets of genes are regulated in the digestive/secretory tract and the carcass. Our results suggest that P450s play a role in metabolizing yet unidentified endogenous compounds and are involved in an as-yet-unknown physiological regulatory feedback loop.

Development of new LSM-83177 analogues as anti-tumor agents against colorectal cancer targeting p53-MDM2 interaction.

LSM-83177, a phenoxy acetic acid derivative, is a small molecule reported for its promising anti-tumor properties. Via inhibiting the interaction between MDM2 and p53, LSM-83177 can elevate the active p53 levels within cells, thereby promoting apoptosis and inhibiting tumor growth. Also, LSM-83177 has been shown to inhibit GST activity in colorectal cancer HT29 cells. In the current work, novel LSM-83177 hydrazone analogs 5a-f, 7a-b, 10a-e, and 13a-b have been designed according to the structure features of LSM-83177 and their binding mode in the active site of MDM2. The anti-cancer activity of the newly synthesized analogs is evaluated against the HT29 cell line. The most potent compounds, 7a and 10a, showed IC50 = 12.48 and 10.44 µg/ml, respectively, when compared with Cisplatin (IC50 = 11.32 µg/ml) as a reference drug. Compounds 7a and 10a were introduced for further inspection for p53-MDM2 protein-protein interaction, where they displayed IC50 values of 3.65 and 11.08 µg/ml, respectively. Furthermore, hydrazones 7a and 10a increased the p-53 expression levels by 3.22- and 4.25-fold, respectively; in addition, they effectively reduced the GST expression levels in HT29 cancer cells with 0.56- and 0.30-fold increments in comparison to the untreated control.

Association of Glutathione Transferase M1, T1, P1 and A1 Gene Polymorphism and Susceptibility to IgA Vasculitis.

Endothelial cell injury is a hallmark of IgA vasculitis (IgAV), possibly associated with various factors, including oxidative stress. Certain single nucleotide polymorphisms (SNPs) of glutathione S-transferases (GST) genes have been shown to increase susceptibility to oxidative stress. The objective of our study was to evaluate the gene polymorphisms of GSTM1, GSTT1, GSTP1, and GSTA1 in patients with IgAV. DNA was extracted from the blood of 124 children with IgAV and 168 age-matched healthy controls. A higher frequency of the GSTM1 null genotype was observed in patients with gastrointestinal (GI) system involvement compared to those without GI system involvement (51.5% vs. 28.6%, p = 0.011). Additionally, the GSTM1 null genotype was less prevalent (30.8% vs. 69.2%, p = 0.032), while the GSTP1 Val/Val genotype was significantly more prevalent in patients who developed urogenital complications (scrotal swelling) during the course of the disease (60% vs. 40%, p = 0.039). This study is the first to suggest an association between GSTM1 and GSTP1 polymorphisms and various phenotypes observed during the clinical course of IgAV in the pediatric population. However, it was performed on a national and likely single ethnic cohort, too small for definitive conclusions, so larger studies are needed to confirm this association.

Cr(VI) behaves differently than Cr(III) in the uptake, translocation and detoxification in rice roots.

Excessive accumulation of chromium (Cr) causes severe damage to both physiological and biochemical processes and consequently growth repression in plants. Hexavalent chromium [Cr(VI)]-elicited alterations in plants have been widely elucidated at either physiological or molecular level, whereas little is known about trivalent chromium [Cr(III)]. Here, we found that both Cr(III) and Cr(VI) significantly inhibited root growth in rice plants. However, rice plants under Cr(VI) showed significantly less inhibition in root growth than those under Cr(III) at low levels, which might be attributed to the different hormetic effects of Cr(III) and Cr(VI) on rice plants. It was unexpected that Cr(III) could be actively taken up by rice roots similarly to Cr(VI); whereas they exhibited different kinetic uptake patterns. Furthermore, root-to-shoot Cr translocation under Cr(VI) was much lower than that under Cr(III). These results indicate that the uptake, translocation, and toxicity of Cr(III) differed greatly from those of Cr(VI). Transcriptome profiling of rice roots revealed that a series of gene families involved in detoxification, including ATP-binding cassette (ABC) transporters, multidrug and toxic compound extrusion proteins (MATEs), and Tau class glutathione S-transferases (GSTUs), were significantly associated with Cr accumulation and detoxification in rice roots. In addition, much more members of these gene families were upregulated by Cr(VI) compared to Cr(III), suggesting their vital roles in Cr uptake, translocation, and detoxification, especially under Cr(VI) stress. Further comparison of gstu9 and gstu10/50 mutants with their wild type confirmed that GSTUs play complex roles in the intracellular Cr transport and redox homeostasis during Cr(III) or Cr(VI) stress. Taken together, our findings provides new insights into the differential behaviors of Cr(III) and Cr(VI) in rice roots, as well as new candidate genes such as OsABCs and OsGSTUs, to further elucidate the mechanisms of the uptake, translocation, and detoxification of Cr(III) and Cr(VI).

Polymorphic Loci of Xenobiotic Biotransformation Genes in Accumulated Mercury Pollution Liquidators and in Workers with Chronic Mercury Vapors Exposure.

The allele and genotype frequencies of the polymorphic loci CYP1A1 (rs1048943), GSTP1 (rs1695 and rs1138272), GSTM1, and GSTT1 genes were studied in 517 men: in 389 accumulated mercury pollution liquidators (207 firefighters of the Ministry of the Russian Federation for Civil Defence, Emergencies and Elimination of Consequences of Natural Disasters and 182 employees of the Federal Environmental Operator) and 128 former workers (82 patients in the delayed period of chronic mercury intoxication and 46 individuals contacted with mercury and had no chronic mercury intoxication). We found differences in the frequencies of AA and AG genotypes in groups of former workers (χ2=6.96, p=0.008) for the polymorphic locus rs1048943, while the AG-CYP1A1 genotype was characterized by a 5.5-fold decrease in the odds ratio for the development of chronic mercury intoxication (OR=0.18, p=0.0041). An unfavorable combination of genotypes of the studied polymorphic loci increases the risk of undesirable health effects.

Effects of compound Anoectochilus roxburghii (Wall.) Lindl. oral liquid on relative metabolic enzymes and various biochemical indices in Wistar rats with isoniazid-induced liver injury.

Isoniazid (INH) is the first-line anti-tuberculosis drug in clinical practice, and its main adverse effect is drug-induced liver injury (DILI). This study aimed to investigate the hepatoprotective effect of Compound Anoectochilus roxburghii (Wall.) Lindl. Oral Liquid (CAROL) and to provide a new strategy for the search of potential drugs against INH-induced liver injury in Wistar rats. Animal experiment was based on INH (100 mg/kg) induced liver injury to explore the intervention effects of CAROL at doses of 1.35, 2.70, and 5.40 mL/kg. LC-QTOF-MS/MS was used to identify hepatoprotective components in CAROL and its' exposed components in rat serum. The hepatoprotective effect of CAROL was evaluated by pathological observation of rat liver tissue and changes in levels of biochemical indices and cytokines in serum or liver tissue. Of the 58 hepatoprotective components identified, 15 were detected in the serum of rats with liver-injured treated by high-dose CAROL. Results of animal experiments showed that the levels of various biochemical indexes and cytokines were significantly reversed with CAROL intervention. In particular, the expression level of cytokeratin-18 and high-mobility group box 1, as specific and sensitive indicators of DILI, was significantly reduced in the serum of rats with CAROL intervention compared with the INH model group. The same reversal was observed in the levels of TBIL, ALP, ALT, and AST in serum, as well as in the levels of TNF-α, IL-6, SOD, and MDA in liver tissue. For INH-metabolizing enzymes, an evident expression inhibition was observed in N-acetyltransferase 2 and glutathione S-transferases with CAROL intervention, which may be the key to controlling INH hepatotoxicity. CAROL has a favorable hepatoprotective effect on INH-induced liver injury. This study takes the first step in studying the hepatoprotective mechanism of CAROL against INH hepatotoxicity and provides reference for wider clinical applications.

Identification and Characterization of the Glutathione S-Transferase Gene Family in Blueberry (Vaccinium corymbosum) and Their Potential Roles in Anthocyanin Intracellular Transportation.

The glutathione S-transferases (GSTs, EC 2.5.1.18) constitute a versatile enzyme family with pivotal roles in plant stress responses and detoxification processes. Recent discoveries attributed the additional function of facilitating anthocyanin intracellular transportation in plants to GSTs. Our study identified 178 VcGST genes from 12 distinct subfamilies in the blueberry genome. An uneven distribution was observed among these genes across blueberry's chromosomes. Members within the same subfamily displayed homogeneity in gene structure and conserved protein motifs, whereas marked divergence was noted among subfamilies. Functional annotations revealed that VcGSTs were significantly enriched in several gene ontology and KEGG pathway categories. Promoter regions of VcGST genes predominantly contain light-responsive, MYB-binding, and stress-responsive elements. The majority of VcGST genes are subject to purifying selection, with whole-genome duplication or segmental duplication serving as key processes that drive the expansion of the VcGST gene family. Notably, during the ripening of the blueberry fruit, 100 VcGST genes were highly expressed, and the expression patterns of 24 of these genes demonstrated a strong correlation with the dynamic content of fruit anthocyanins. Further analysis identified VcGSTF8, VcGSTF20, and VcGSTF22 as prime candidates of VcGST genes involved in the anthocyanin intracellular transport. This study provides a reference for the exploration of anthocyanin intracellular transport mechanisms and paves the way for investigating the spectrum of GST functions in blueberries.

Target-site and non-target-site resistance mechanisms confer mesosulfuron-methyl resistance in Alopecurus aequalis.

BACKGROUND: Shortawn foxtail (Alopecurus aequalis Sobol.) is a noxious weed in China. The resistance of A. aequalis developed rapidly due to the long-term application of acetolactate synthase (ALS)-inhibiting herbicides. Here, a suspected mesosulfuron-methyl-resistant A. aequalis population, Aa-R, was collected from a wheat field in China. RESULTS: A dose‒response test showed that the Aa-R population has evolved a high level of resistance to mesosulfuron-methyl, and its growth was suppressed by imazamox, pyroxsulam and bispyribac-sodium. ALS gene sequence analysis revealed that a known resistance-related mutation (Pro-197-Thr) was present in the Aa-R population. Moreover, ALS gene overexpression was detected in the Aa-R population. The mesosulfuron-methyl resistance could be reversed by cytochrome P450 monooxygenase (CYP450) and glutathione S-transferase (GST) inhibitors. In addition, enhanced metabolism of mesosulfuron-methyl was detected in the Aa-R population compared with the susceptible population. NADPH-cytochrome P450 reductase and GST activities were strongly inducible in the Aa-R population. One CYP450 gene, CYP74A2, and one GST gene, GST4, were constitutively upregulated in the Aa-R population. Molecular docking results showed the binding affinity of CYP74A2 and GST4 for the tested ALS-inhibiting herbicides, respectively. CONCLUSION: This study confirmed that target-site resistance and non-target-site resistance involving CYP450 and GST were the main mechanisms involved in resistance in the mesosulfuron-methyl-resistant A. aequalis population.

GSTM1 and GSTP1 Polymorphisms Affect Outcome in Colorectal Adenocarcinoma.

Background and Objectives: Despite improvements in screening programs, a large number of patients with colorectal cancer (CRC) are diagnosed in an advanced disease stage. Previous investigations imply that glutathione transferases (GSTs) might be associated with the development and progression of CRC. Moreover, the detoxification mechanism of oxaliplatin, which represents the first line of treatment for advanced CRC, is mediated via certain GSTs. The aim of this study was to evaluate the significance of certain GST genetic variants on CRC prognosis and the efficacy of oxaliplatin-based treatment. Materials and Methods: This prospective study included 523 patients diagnosed with CRC in the period between 2014 and 2016, at the Digestive Surgery Clinic, University Clinical Center of Serbia, Belgrade. Patients were followed for a median of 43.47 ± 17.01 months (minimum 1-63 months). Additionally, 109 patients with advanced disease, after surgical treatment, received FOLFOX6 treatment as a first-line therapy between 2014 and 2020. The Kaplan-Meier method was used to analyze cumulative survival, and the Cox proportional hazard regression model was used to study the effects of different GST genotypes on overall survival. Results: Individuals with the GSTM1-null genotype and the GSTP1 IleVal+ValVal (variant) genotype had significantly shorter survival when compared to referent genotypes (GSTM1-active and GSTP1 IleIle) (log-rank: p = 0.001). Moreover, individuals with the GSTM1-null genotype who received 5-FU-based treatment had statistically significantly shorter survival when compared to individuals with the GSTM1-active genotype (log-rank: p = 0.05). Conclusions: Both GSTM1-null and GSTP1 IleVal+ValVal (variant) genotypes are associated with significantly shorter survival in CRC patients. What is more, the GSTM1-null genotype is associated with shorter survival in patients receiving FOLOFOX6 treatment.

Evaluation of the association between glutathione S-transferase polymorphisms and susceptibility to cutaneous melanoma: a systematic review and meta-analysis.

Introduction: Glutathione S-transferase (GST) enzymes play a crucial role in detoxification by catalysing the conjugation of many hydrophobic and electrophilic compounds with reduced glutathione. Polymorphisms in GST genes may influence the susceptibility to various cancers, including melanoma. Aim: We reported a systematic review and meta-analysis to evaluate the association between GST polymorphisms and susceptibility to cutaneous melanoma. Material and methods: A comprehensive search of four databases, namely PubMed, Scopus, Cochrane Library, and Web of Science, was conducted to gather pertinent studies up until 24 August 2023. No restrictions were imposed during the search. The analysis included 32 studies and was broken down into subgroups based on ethnicity, control source, control matching, quality score, and sample size. Results: The forest plot analyses on GSTM1, GSTT1, combined GSTM1/GSTT1, and GSTP1 polymorphisms in relation to melanoma risk showed no statistically significant differences between the case and control groups, except for the recessive model of GSTP1 polymorphism. The analysis revealed significant associations between GSTM1 polymorphisms and melanoma risk in Asians and in studies with a sample size of less than 200. For the combined GSTM1/GSTT1 polymorphisms, a significant association was found in hospital-based controls. Conclusions: While this study enhances our understanding of the genetic factors influencing melanoma risk, it also highlights the need for further research. The current evidence is not sufficient to confirm or reject the intervention effect. Future research should consider gene-gene and gene-environment interactions, which could offer a more comprehensive understanding of the complex biology of melanoma.

Genotoxicity in humans exposed to arsenic, lithium, and boron in drinking water in the Bolivian Andes-A cross sectional study.

Elevated concentrations of arsenic, lithium and boron in drinking water have already been reported in Bolivia. Arsenic is known to cause genotoxicity but that caused by lithium and boron is less well known. The aim of the present cross-sectional study was to evaluate potential genotoxic effects of exposure to arsenic, while considering exposure to lithium and boron and genetic susceptibility. Women (n = 230) were recruited in villages located around Lake Poopó. Exposure to arsenic was determined as the sum of concentrations of arsenic metabolites inorganic arsenic, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) in urine. Exposure to lithium and boron was determined based on their concentrations in urine. Genetic susceptibility was determined by GSTM1 (glutathione S-transferase-mu-1) and GSTT1 (glutathione S-transferase-theta-1) null genotypes and AS3MT (Arsenite Methyltransferase) rs3740393. Genotoxicity was measured in peripheral blood leukocytes using the comet assay. The geometric means of arsenic, lithium, and boron concentrations were 68, 897, and 3972 µg/L, respectively. GSTM1 and GSTT1 null carriers had more DNA strand breaks than gene carriers (p = .008, p = .005). We found no correlation between urinary arsenic and DNA strand breaks (rS = .03, p = .64), and only a weak non-significant positive association in the adjusted multivariate analysis (ß = .09 [-.03; .22], p = .14). Surprisingly, increasing concentrations of lithium in urine were negatively correlated with DNA strand breaks (rS = -.24, p = .0006), and the association persisted in multivariate analysis after adjusting for arsenic (ß = -.22 [-.36; -.08], p = .003). We found no association between boron and DNA strand breaks. The apparent protective effect of lithium merits further investigation.

Translocation, enzymatic reduction and toxicity of dimethylarsenate in rice.

Dimethylarsenate [DMAs(V)] can be produced by some soil microorganisms through methylation of inorganic arsenic (As), especially in anoxic paddy soils. DMAs(V) is more phytotoxic than inorganic As and can cause the physiological disorder straighthead disease in rice. Rice cultivars vary widely in the resistance to DMAs(V), but the mechanism remains elusive. Here, we investigated the differences in DMAs(V) uptake, translocation, and reduction to dimethylarsenite [DMAs(III)], as well as the effects on the metabolome, between two rice cultivars Mars and Zhe733. We found that Mars was 11-times more resistant to DMAs(V) than Zhe733. Mars accumulated more DMAs(V) in the roots, whereas Zhe733 translocated more DMAs(V) to the shoots and reduced more DMAs(V) to DMAs(III). DMAs(III) was more toxic than DMAs(V). Using heterologous expression and in vitro enzyme assays, we showed that the glutathione-S-transferases OsGSTU17 and OsGSTU50 were able to reduce DMAs(V) to DMAs(III). The expression levels of OsGSTU17 and OsGSTU50 were higher in the shoot of Zhe733 compared to Mars. Metabolomic analysis in rice shoots showed that glutathione (GSH) metabolism was perturbed by DMAs(V) toxicity in Zhe733. Application of exogenous GSH significantly alleviated the toxicity of DMAs(V) in Zhe733. Taken together, the results suggest that Mars is more resistant to DMAs(V) than Zhe733 because of a lower root-to-shoot translocation and a smaller capacity to reduce DMAs(V) to DMAs(III).

Characterization of three glutathione S-transferases potentially associated with adaptation of the wheat blossom midge Sitodiplosis mosellana to host plant defense.

BACKGROUND: Insect glutathione S-transferases (GSTs), a multifunctional protein family, play a crucial role in detoxification of plant defensive compounds. However, they have been rarely investigated in Sitodiplosis mosellana, a destructive pest of wheat worldwide. In this study, we characterized for the first time a delta (SmGSTd1) and two epsilon GST genes (SmGSTe1 and SmGSTe2) and analyzed their expression patterns and functions associated with adaptation to host plant defense in this species. RESULTS: Expression of these SmGST genes greatly increased in S. mosellana larvae feeding on resistant wheat varieties Kenong1006, Shanmai139 and Jinmai47 which contain higher tannin and ferulic acid, the major defensive compounds of wheat against this pest, compared with those feeding on susceptible varieties Xinong822, Xinong88 and Xiaoyan22. Their expression was also tissue-specific, most predominant in larval midgut. Recombinant SmGSTs expressed in Escherichia coli could catalyze the conjugation of 1-chloro-2,4-dinitrobenzene, with activity peak at pH around 7.0 and temperature between 30 and 40 °C. Notably, they could metabolize tannin and ferulic acid, with the strongest metabolic ability by SmGSTe2 against two compounds, followed by SmGSTd1 on tannin, and SmGSTe1 on ferulic acid. CONCLUSION: The results suggest that these SmGSTs are important in metabolizing wheat defensive chemicals during feeding, which may be related to host plant adaptation of S. mosellana. Our study has provided information for future investigation and development of strategies such as host-induced gene silencing of insect-detoxifying genes for managing pest adaptation. © 2023 Society of Chemical Industry.

Exposure to nickel chloride induces epigenetic modification on detoxification enzyme glutathione S-transferase M2.

Nickel (Ni) is a human carcinogen with genotoxic and epigenotoxic effects. Environmental and occupational exposure to Ni increases the risk of cancer and chronic inflammatory diseases. Our previous findings indicate that Ni alters gene expression through epigenetic regulation, specifically impacting E-cadherin and angiopoietin-like 4 (ANGPTL4), involved in epithelial-mesenchymal transition and migration. GST-M2, a member of the glutathione S-transferase (GST) enzyme family, plays a crucial role in cellular defense against oxidative damage and has been increasingly associated with cancer. GST-M2 overexpression inhibits lung cancer invasion and metastasis in vitro and in vivo. Hypermethylation of its promoter in cancer cells reduces gene expression, correlating with poor prognosis in non-small-cell lung cancer patients. The impact of Ni on GST-M2 remains unclear. We will investigate whether nickel exerts regulatory effects on GST-M2 through epigenetic modifications. Additionally, metformin, an antidiabetic drug, is being studied as a chemopreventive agent against nickel-induced damage. Our findings indicate that nickel chloride (NiCl2 ) exposure, both short-term and long-term, represses GST-M2 expression. However, the expression can be restored by demethylation agent 5-aza-2'-deoxycytidine and metformin. NiCl2 promotes hypermethylation of the GST-M2 promoter, as confirmed by methylation-specific PCR and bisulfite sequencing. Additionally, NiCl2 also influences histone acetylation, and metformin counteracts the suppressive effect of NiCl2 on histone H3 expression. Metformin reestablishes the binding of specificity protein 1 to the GST-M2 promoter, which is otherwise disrupted by NiCl2 . These findings elucidate the mechanism by which Ni reduces GST-M2 expression and transcriptional activity, potentially contributing to Ni-induced lung carcinogenesis.

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.

Decreased Klotho Expression Causes Accelerated Decline of Male Fecundity through Oxidative Injury in Murine Testis.

Oxidative stress is the etiology for 30-80% of male patients affected by infertility, which is a major health problem worldwide. Klotho protein is an aging suppressor that functions as a humoral factor modulating various cellular processes including antioxidation and anti-inflammation, and its dysregulation leads to human pathologies. Male mice lacking Klotho are sterile, and decreased Klotho levels in the serum are observed in men suffering from infertility with lower sperm counts. However, the mechanism by which Klotho maintains healthy male fertility remains unclear. Klotho haplodeficiency (Kl+/-) accelerates fertility reduction by impairing sperm quality and spermatogenesis in Kl+/- mice. Testicular proteomic analysis revealed that loss of Klotho predominantly disturbed oxidation and the glutathione-related pathway. We further focused on the glutathione-S-transferase (GST) family which counteracts oxidative stress in most cell types and closely relates with fertility. Several GST proteins, including GSTP1, GSTO2, and GSTK1, were significantly downregulated, which subsequently resulted in increased levels of the lipid peroxidation product 4-hydroxynonenal and apoptosis in murine testis with low or no expression of Klotho. Taken together, the loss of one Kl allele accelerates male fecundity loss because diminished antioxidant capability induces oxidative injury in mice. This is the first study that highlights a connection between Klotho and GST proteins.

OsGSTU17, a Tau Class Glutathione S-Transferase Gene, Positively Regulates Drought Stress Tolerance in Oryza sativa.

As a great threat to the normal growth of rice, drought not only restricts the growth of rice, but also affects its yield. Glutathione S-transferases (GSTs) have antioxidant and detoxification functions. In rice, GSTs can not only effectively cope with biological stress, but also play a defense role against abiotic stress. In this study, we selected OsGSTU17, a member gene that was induced by drought, to explore the role of GSTs and analyze their physiological mechanisms that are involved in rice drought tolerance. With the CRISPR/Cas9 knockout system techniques, we obtained two independent mutant lines of osgstu17. After 14 days of drought stress treatment, and then re-supply of the water for 10 days, the survival rate of the osgstu17 mutant lines was significantly reduced compared to the wild-type (WT). Similarly, with the 10% (w/v) PEG6000 hydroponics experiment at the seedling stage, we also found that compared with the WT, the shoot and root biomass of osgstu17 mutant lines decreased significantly. In addition, both the content of the MDA and H2O2, which are toxic to plants, increased in the osgtu17 mutant lines. On the other hand, chlorophyll and proline decreased by about 20%. The activity of catalase and superoxide dismutase, which react with peroxides, also decreased by about 20%. Under drought conditions, compared with the WT, the expressions of the drought stress-related genes OsNAC10, OsDREB2A, OsAP37, OsP5CS1, OsRAB16C, OsPOX1, OsCATA, and OsCATB in the osgtu17 mutant lines were significantly decreased. Finally, we concluded that knocking out OsGSTU17 significantly reduced the drought tolerance of rice; OsGSTU17 could be used as a candidate gene for rice drought-tolerant cultivation. However, the molecular mechanism of OsGSTU17 involved in rice drought resistance needs to be further studied.

Functional analysis of an overexpressed glutathione S-transferase BdGSTd5 involved in malathion and malaoxon detoxification in Bactrocera dorsalis.

Glutathione S-transferases (GSTs) are one of the three detoxification enzyme families. The constitutive and inducible overexpression of GSTs genes plays an important role in insecticide resistance. Previous study showed that malathion resistance was polygenic, and elevated GSTs activity was one of the important factor participating in malathion resistance of Bactrocera dorsalis (Hendel), a serious economic pest worldwide. BdGSTd5 overexpression was inducible upon exposure to malathion. However, the involvement of BdGSTd5 in malathion resistance has not been clarified. In this study, we found that BdGSTd5 sequence harbored the conserved region of delta class GSTs, which were overexpressed in malathion resistant strain of B. dorsalis compared to malathion susceptible strain. The highest mRNA expression level of BdGSTd5 was found in 1-day-old adult, and the levels decreased with aging. The dsBdGSTd5 injection effectively silenced (73.4% reduction) the expression of BdGSTd5 and caused significant increase in susceptibility to malathion with a cumulative mortality increasing of 13.5% at 72 h post malathion treatment (p < 0.05). Cytotoxicity assay demonstrated that BdGSTd5 was capable of malathion detoxification. Molecular docking analysis further indicated the interactive potential of BdGSTd5 with malathion and its toxic oxide malaoxon. The recombinant BdGSTd5 exhibited glutathione-conjugating activity toward 1-chloro-2, 4-dinitrobenzene and malathion and malaoxon metabolic capacity with significant reduction (p < 0.05) of the peak areas by 90.0% and 73.1%, respectively. Taken together, the overexpressed BdGSTd5 contributes to malathion metabolism and resistance, which detoxify the malathion in B. dorsalis via directly depleting malathion and malaoxon.

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 flucarbazone­sodium), but was susceptible to pyrithiobac­sodium. 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.

Progonostic effect of GSTM1/GSTT1 polymorphism in determining cardiovascular diseases risk among type 2 diabetes patients in South Indian population.

BACKGROUND: Cardiovascular disease (CVD) is a significant complication of type 2 diabetes mellitus (T2DM), with oxidative stress playing a significant role. Glutathione S-transferase (GST) polymorphisms - GSTM1, GSTT1 - have been linked to CVD and T2DM. The role of GSTM1 and GSTT1 in CVD development among T2DM patients in the South Indian population is investigated in this study. MATERIALS AND METHODS: The volunteers were grouped as Group 1: control, Group 2: T2DM, Group 3: CVD, and Group 4: T2DM with CVD (n = 100 each). Blood glucose, lipid profile, plasma GST, MDA, and total antioxidants were measured. GSTM1 and GSTT1 were genotyped using PCR. RESULTS: GSTT1 plays a significant role in the development of T2DM and CVD [OR 2.96(1.64-5.33), < 0.001 and 3.05(1.67-5.58), < 0.001] while GSTM1 null genotype was not associated with disease development. Individuals with dual null GSTM1/GSTT1 genotype had the highest risk of developing CVD [3.70(1.50-9.11), 0.004]. Group 2 and 3 individuals showed higher lipid peroxidation and lower total antioxidant levels. Pathway analysis further indicated that GSTT1 significantly affects GST plasma levels. CONCLUSION: GSTT1 null genotype may be considered a contributing factor that increases the susceptibility and risk of CVD and T2DM in the South Indian population.