Expression Of Glutathione S-transferase Research Articles

4-Octyl itaconate alleviates dextran sulfate sodium-induced ulcerative colitis in mice via activating the KEAP1-NRF2 pathway.

Ulcerative colitis (UC) is a chronic idiopathic inflammatory bowel disease with a relapsing-remitting course. Although its etiology remains unknown, excessive oxidative stress in colon is a major intermediate factor that can promote the progression of UC. In the present study, we investigated the effect and the underlying mechanisms of 4-Octyl itaconate (OI) on dextran sulfate sodium (DSS)-induced UC in mice. Our work identified that OI alleviated the colitis by reducing the oxidative stress and the apoptosis in colon tissue, then increasing the tight junction proteins expression and in turn enhancing the intestinal barrier function, thereby creating less severe inflammatory responses. Moreover, our results demonstrated that OI reduced the Kelch-like ECH-associated protein 1 (KEAP1) expression and subsequent upregulated nuclear factor E2-related factor (NRF2) expression and its nuclear translocation which in turn induced the expression of glutathione S-transferase (GST) and NAD(P)H: quinone oxidoreductase 1 (NQO1). In addition, ML385, a NRF2 antagonist, can inhibit the protective effects of OI on UC, indicating that the role of OI in this colitis model could be dependent on the activation of KEAP1-NRF2 pathway. Notably, OI co-administration significantly enhanced the therapeutic effects of mesalazine or 1400W on UC. Collectively, itaconate may have a great potential for use in the treatment of IBD.

A glutathione S-transferase from Thinopyrum ponticum confers Fhb7 resistance to Fusarium head blight in wheat.

Fusarium head blight (FHB), mainly incited by Fusarium graminearum Schwabe, has caused great losses in grain yield and quality of wheat globally. Fhb7, a major gene from 7E chromosome of Thinopyrum ponticum, confers broad resistance to multiple Fusarium species in wheat, and has recently been cloned and identified as encoding a glutathione S-transferase (GST). However, some recent reports raised doubt about if GST is the causal gene of Fhb7. To resolve the discrepancy and validate the gene function of GST in wheat, we phenotyped Fhb7 near-isogenic lines (Jimai22-Fhb7 vs Jimai22) and GST over-expressed lines for FHB resistance. Jimai22-Fhb7 showed significantly higher FHB resistance with a lower percentage of symptomatic spikelets (PSS), Fusarium-damaged kernel (FDK) and Deoxynivalenol (DON) content than susceptible Jimai22 in three experiments. All the positive GST transgenic lines driven by either the maize ubiquitin promoter (MubiP) or its native promoter (NP) with high gene expression in the wheat cultivar 'Fielder' showed high FHB resistance. Only one MubiP-driven transgenic line showed low GST expression and similar susceptibility as Fielder, suggesting high GST expression confers Fhb7 resistance to FHB. Knockout of GST in Jimai22-Fhb7 line using CRISPR-Cas9-based gene-editing showed significantly higher FHB susceptibility compared with the non-edited control plants. Therefore, we confirmed GST as the causal gene of Fhb7 for FHB resistance. Considering its major effect on FHB resistance, pyramiding Fhb7 with other QTLs has a great potential to create highly FHB-resistant wheat cultivars.

Role of glutathione S-transferases in the mode of action of herbicides that inhibit amino acid synthesis in Amaranthus palmeri

Acetolactate synthase inhibitors (ALS inhibitors) and glyphosate are two classes of herbicides that act by inhibiting an enzyme in the biosynthetic pathway of branched-chain or aromatic amino acids, respectively. Besides amino acid synthesis inhibition, both herbicides trigger similar physiological effects in plants. The main aim of this study was to evaluate the role of glutathione metabolism, with special emphasis on glutathione S-transferases (GSTs), in the mode of action of glyphosate and ALS inhibitors in Amaranthus palmeri. For that purpose, plants belonging to a glyphosate-sensitive (GLS) and a glyphosate-resistant (GLR) population were treated with different doses of glyphosate, and plants belonging to an ALS-inhibitor sensitive (AIS) and an ALS-inhibitor resistant (AIR) population were treated with different doses of the ALS inhibitor nicosulfuron. Glutathione-related contents, GST activity, and related gene expressions (glutamate-cysteine ligase, glutathione reductase, Phi GST and Tau GST) were analysed in leaves. According to the results of the analytical determinations, there were virtually no basal differences between GLS and GLR plants or between AIS and AIR plants. Glutathione synthesis and turnover did not follow a clear pattern in response to herbicides, but GST activity and gene expression (especially Phi GSTs) increased with both herbicides in treated sensitive plants, possibly related to the rocketing H2O2 accumulation. As GSTs offered the clearest results, these were further investigated with a multiple resistant (MR) population, compressing target-site resistance to both glyphosate and the ALS inhibitor pyrithiobac. As in single-resistant plants, measured parameters in the MR population were unaffected by herbicides, meaning that the increase in GST activity and expression occurs due to herbicide interactions with the target enzymes.

Glutathione S-transferase activity facilitates rice tolerance to the barnyard grass root exudate DIMBOA

BackgroundIn paddy fields, the noxious weed barnyard grass secretes 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) to interfere with rice growth. Rice is unable to synthesize DIMBOA. Rice cultivars with high or low levels of allelopathy may respond differently to DIMBOA.ResultsIn this study, we found that low concentrations of DIMBOA (≤ 0.06 mM) promoted seedling growth in allelopathic rice PI312777, while DIMBOA (≤ 0.08 mM) had no significant influence on the nonallelopathic rice Lemont. DIMBOA treatment caused changes in the expression of a large number of glutathione S-transferase (GST) proteins, which resulting in enrichment of the glutathione metabolic pathway. This pathway facilitates plant detoxification of heterologous substances. The basal levels of GST activity in Lemont were significantly higher than those in PI312777, while GST activity in PI312777 was slightly induced by increasing DIMBOA concentrations. Overexpression of GST genes (Os09g0367700 and Os01g0949800) in these two cultivars enhanced rice resistance to DIMBOA.ConclusionsTaken together, our results indicated that different rice accessions with different levels of allelopathy have variable tolerance to DIMBOA. Lemont had higher GST activity, which helped it tolerate DIMBOA, while PI312777 had lower GST activity that was more inducible. The enhancement of GST expression facilitates rice tolerance to DIMBOA toxins from barnyard grass root exudates.

Investigation of the effect of isoxazole derivatives on glutathione-dependent enzymes associated with cancer

Globally, cancer is currently the second-most common cause of death. As such, it is a crucial problem that affects society's well-being all around the world. Chemotherapy is the most commonly used treatment for cancer. It is a technique that uses drugs to kill cancerous cells or the cancerous organism itself. Chemotherapy has been used to treat metastatic cancer for the past 50 years, with varying degrees of effectiveness. One of the main problems with many chemotherapeutic drugs is that they might damage healthy cells and organs. These drugs frequently have a low therapeutic index, a restricted ability to selectively target cancerous cells, and a high propensity to develop drug resistance after extended use. Furthermore, a rise in the expression of glutathione reductase (GR; EC 1.8.1.7) and glutathione S-transferase (GST; EC 2.5.1.18) can be seen with time. Extensive study on proteins and their functions in the development of cancer cells has been conducted in recent years. Glutathione-S-transferases (GSTs) are a superfamily of enzymes that play a critical role in the detoxification of cells by protecting them against reactive electrophiles such as chemotherapeutic drugs and reactive oxygen species. Glutathione reductase (GR), on the other hand, is an essential antioxidant enzyme that supports cellular protection against oxidative stress. In addition to its antioxidant role, GR has become a target for the synthesis of antimalarial and anticancer medications. In the current investigation, affinity chromatography was used to purificate the GST and GR enzymes from human erythrocytes. Through the calculation of IC50 and KI values for these derivatives, the effects of isoxazole derivatives on these purified enzymes were examined, with an emphasis on identifying the forms of inhibition.

Phytochelatin-Mediated Cultivar-Dependent Cd Accumulations of Lactuca sativa and Implication for Cd Pollution-Safe Cultivars Screening.

Cd pollution-safe cultivar (Cd-PSC) is a feasible strategy to minimize Cd contamination in leafy vegetables. The shoot Cd concentrations of 23 Lactuca sativa cultivars under Cd stress ranged from 0.124 to 2.155 mg·kg-1 with a maximum cultivar difference of 8 folds. Typical Cd-PSC C16 (L) and high-Cd-accumulating cultivar C13 (H) were screened to investigate the mechanisms of Cd accumulations in L. sativa through determining Cd concentrations, Cd subcellular distributions, phytochelatin profiles, and phytochelatin biosynthesis-related genes' expressions. Higher Cd distribution in a heat stable fraction in C13 (H) indicated that the high Cd accumulation trait of C13 (H) mainly depended on the Cd-phytochelatin complexes. Root phytochelatin concentrations were significantly elevated in C13 (H) (5.83 folds) than in C16 (L) (2.69 folds) (p < 0.05) under Cd stress. Significantly downregulated expressions of glutathione S-transferase rather than the regulation of phytochelatin synthesis genes in the root of C13 (H) might be responsible for sufficient glutathione supply for phytochelatins synthesis. These findings suggested that phytochelatin elevation in C13 (H) would favor the Cd root to shoot transportation, which provides new insights into the phytochelatin-related cultivar-dependent Cd accumulating characteristic in L. sativa.

Female-specific pancreatic cancer survival from CT imaging of visceral fat implicates glutathione metabolism in solid tumors

To identify if body composition, assessed with preoperative CT-based visceral fat ratio quantification as well as tumor metabolic gene expression, predicts sex-dependent overall survival (OS) in patients with pancreatic ductal adenocarcinoma (PDAC). This was a retrospective analysis of preoperative CT in 98 male and 107 female patients with PDAC. Relative visceral fat (rVFA; visceral fat normalized to total fat) was measured automatically using software and corrected manually. Median and optimized rVFA thresholds were determined according to published methods. Kaplan Meier and log-rank tests were used to estimate OS. Multivariate models were developed to identify interactions between sex, rVFA, and OS. Unsupervised gene expression analysis of PDAC tumors from The Cancer Genome Atlas (TCGA) was performed to identify metabolic pathways with similar survival patterns to rVFA. Optimized preoperative rVFA threshold of 38.9% predicted significantly different OS in females with a median OS of 15 months (above threshold) vs 24 months (below threshold; p=0.004). No significant threshold was identified in males. This female-specific significance was independent of age, stage, and presence of chronic pancreatitis (p=0.02). Tumor gene expression analysis identified female-specific stratification from a five-gene signature of glutathione S-transferases. This was observed for PDAC as well as clear cell renal carcinoma and glioblastoma. CT-based assessments of visceral fat can predict pancreatic cancer OS in females. Glutathione S-transferase expression in tumors predicts female-specific OS in a similar fashion.

Rapid discovery of a novel “green” and natural GST inhibitor for sensitizing hepatocellular carcinoma to Cisplatin by visual screening strategy

Over-expression of glutathione S-transferase (GST) can promote Cisplatin resistance in hepatocellular carcinoma (HCC) treatment. Hence, inhibiting GST is an attractive strategy to improve Cisplatin sensitivity in HCC therapy. Although several synthesized GST inhibitors have been developed, the side effects and narrow spectrum for anticancer seriously limit their clinical application. Considering the abundance of natural compounds with anticancer activity, this study developed a rapid fluorescence technique to screen “green” natural GST inhibitors with high specificity. The fluorescence assay demonstrated that schisanlactone B (hereafter abbreviated as C1) isolated from Xue tong significantly down-regulated GST levels in Cisplatin-resistant HCC cells in vitro and in vivo. Importantly, C1 can selectively kill HCC cells from normal liver cells, effectively improving the therapeutic effect of Cisplatin on HCC mice by down-regulating GST expression. Considering the high GST levels in HCC patients, this compound demonstrated the high potential for sensitizing HCC therapy in clinical practice by down-regulating GST levels.

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.

Validation of biomarkers for neonicotinoid exposure in Folsomia candida under mutual exposure to diethyl maleate.

Neonicotinoid insecticides are harmful to non-target soil invertebrates, which are crucial for sustainable agriculture. Gene expression biomarkers could provide economic and high-throughput metrics of neonicotinoid exposure and toxicity to non-target invertebrates. Thereby, biomarkers can help guide remediation efforts or policy enforcement. Gene expression of Glutathione S-Transferase 3 (GST3) has previously been proposed as a biomarker for the neonicotinoid imidacloprid in the soil ecotoxicological model species Folsomia candida (Collembola). However, it remains unclear how reliably gene expression of neonicotinoid biomarkers, such as GST3, can indicate the exposure to the broader neonicotinoid family under putative GST enzymatic inhibition. In this work, we exposed springtails to two neonicotinoids, thiacloprid and imidacloprid, alongside diethyl maleate (DEM), a known GST metabolic inhibitor that imposes oxidative stress. First, we determined the influence of DEM on neonicotinoid toxicity to springtail fecundity. Second, we surveyed the gene expression of four biomarkers, including GST3, under mutual exposure to neonicotinoids and DEM. We observed no effect of DEM on springtail fecundity. Moreover, the expression of GST3 was only influenced by DEM under mutual exposure with thiacloprid but not with imidacloprid. The results indicate that GST3 is not a robust indicator of neonicotinoid exposure and that probable GST enzymatic inhibition mediates the toxicity of imidacloprid and thiacloprid differentially. Future research should investigate biomarker reliability under shifting metabolic conditions such as provided by DEM exposure.

Expression comparisons of defense-related genes in resistant and susceptible chickpea cultivars in response to Ascochyta rabiei

Ascochyta blight caused by Ascochyta rabiei is a destructive disease affecting chickpea crops worldwide. Numerous studies have sought to identify resistance genes involved in the defense response against Ascochyta blight, but the function of potential resistant genes across different chickpea genetic backgrounds remains poorly understood. This study evaluated the potential role of 16 genes involved in defense responses in partially resistant (ILC482) and susceptible (Sarı98) chickpea cultivars. The leaf samples were collected from 2-week-old seedlings at 6, 12, 24, 48, and 72 h post-inoculation (hpi) with A. rabiei and analyzed for differential expression of defense genes using qRT-PCR. Twelve out of 16 genes were differentially regulated between chickpea cultivars. The qRT-PCR analysis indicated that the expression of defense genes was significantly higher in the partially resistant cultivar than that in the susceptible cultivar. The time point of the highest upregulation ratio for defense genes was variable between the cultivars. The expression of glutathione S-transferase, serine/threonine-protein kinase, WRKY gene (CaWRKY16), and wall associated-receptor kinase genes reached maximum levels in the resistant cultivar at 6 hpi, while antimicrobial peptide precursor (SNAKIN2), polymorphic antigen membrane protein, ethylene receptor-like sequences (CaETR1), and two nucleotide-binding site-leucine-rich repeat genes showed the highest activity at 24 hpi. In particular, CaWRKY16, CaWRKY50, glutathione S-transferase, CaETR1, and wall-associated-receptor kinase genes provided valuable information for assessing chickpea cultivars with different resistance levels. The results indicated that the expression changes of these genes involved in defense pathways play a crucial role in enhanced resistance of chickpea plants against Ascochyta blight and, therefore could be potential candidate genes for future breeding studies.

Effect of hexavalent chromium exposure on the reproductive status and biomarker responses of female Geloina erosa.

Hexavalent chromium (Cr (VI)) is widely distributed in the marine environment of Hainan Province, China and poses a potential threat to its mangrove ecosystems. However, the mechanisms underlying Cr-induced stress and reproductive toxicity in clams remain largely unknown. In this study, the clams, Geloina erosa, were exposed to 4.34, 8.69, 17.38 and 34.76 mg/L Cr (VI) for 24, 48 and 72 h. The gonad-somatic index (GSI) was determined and histological alterations of the ovaries were quantified by light microscopy. The micronucleus test was performed which quantifies the genotoxic presence of small cytoplasmic bodies in eukaryotic cells. Enzymatic assays for catalase (CAT), glutathione reductase (GR), and malondialdehyde (MDA) activities were done. Quantitative real-time PCR (qRT-PCR) was used to quantify the expression of glutathione-S-transferase (GST), heat shock protein 70 (HSP70) and vitellogenin (Vtg) in ovaries of G. erosa. The results showed that the micronucleus frequency was significantly increased when clams were exposed to Cr (VI). Cr (VI) exposure induced the accumulation of MDA and affected CAT and GR enzyme activities. The high Cr (VI) concentration of 34.76 mg/L significantly increased the levels of GR activity, GST expression and HSP70 expression and inhibited Vtg expression and CAT activity. MDA content was significantly increased after 72 h at the high Cr (VI) exposure (34.76 mg/L). Therefore, Cr (VI) exposure may be toxic to the development of ovaries of G. erosa.

Ecological effects and molecular mechanisms of single and coexisting PFOS and Cu exposure on submerged macrophytes and periphytic biofilms in aquatic environments

Perfluorooctane sulfonate (PFOS) is an accumulative emerging persistent organic pollutant that coexists with copper (Cu) in aquatic environments and is a severe threat to human health. PFOS has genotoxicity, male reproductive toxicity, neurotoxicity, developmental toxicity and endocrine disrupting effects, and is considered to be a kind of environmental pollutant with systemic multi-organ toxicity. However, the combined effects of PFOS and Cu on aquatic organisms have not been analyzed previously. In this study, we investigate the response of Vallisneria Natans (V. natans) and biofilms to single and combined treatments of PFOS and Cu at environmental concentrations (1.0, 10.0, and 100.0 μg·L−1). Results indicate that single and combined treatment triggered the reactive oxygen species (ROS) metabolism with increased activities of GSH, MDA, CAT, TSOD and an antagonistic joint toxicity. Meanwhile, transcriptomic analyses showed that the peroxidase (PER), 9 glutaredoxin (GRX), and 39 glutathione S-transferase (GST) expression of genes related to ROS detoxification was up-regulated. In addition, single and combined exposure induced the up-regulation of the transport channel genes which encode aquaporins, rapid-type anion channels, and copper-exporting P-type ATPase transporters, promoting the uptake of PFOS and Cu in V. natans, Enhancing detoxification and mitigating the effects of Cu and PFOS exposure. Moreover, PFOS and Cu changed the structural characteristics of extracellular polysaccharides in biofilms, synthesizing large amounts of β-D-glucopyranose PS, α-D-glucopyranose PS. And the community diversity and species evenness changed, with Rhizobiaceae, Chloroplast, and Weeksellaceae being the dominant phylum. This study provides insights into the molecular mechanism of joint toxicity of PFOS and Cu by Transcriptomics and PCR analysis on the submerged macrophyte and their periphyton biofilms.

Nomilin and its analogue obacunone alleviate NASH and hepatic fibrosis in mice via enhancing antioxidant and anti-inflammation capacity.

Nonalcoholic steatohepatitis (NASH) and hepatic fibrosis are leading causes of cirrhosis with rising morbidity and mortality worldwide. Currently, there is no appropriate treatment for NASH and hepatic fibrosis. Many studies have shown that oxidative stress is a main factor inducing NASH. Nomilin (NML) and obacunone (OBA) are limonoid compounds naturally occurring in citrus fruits with various biological properties. However, whether OBA and NML have beneficial effects on NASH remains unclear. Here, we demonstrated that OBA and NML inhibited hepatic tissue necrosis, inflammatory infiltration and liver fibrosis progression in methionine and choline-deficient (MCD) diet, carbon tetrachloride (CCl4 )-treated and bile duct ligation (BDL) NASH and hepatic fibrosis mouse models. Mechanistic studies showed that NML and OBA enhanced anti-oxidative effects, including reduction of malondialdehyde (MDA) level, increase of catalase (CAT) activity and the gene expression of glutathione S-transferases (GSTs) and Nrf2-keap1 signaling. Additional, NML and OBA inhibited the expression of inflammatory gene interleukin 6 (Il-6), and regulated the bile acid metabolism genes Cyp3a11, Cyp7a1, multidrug resistance-associated protein 3 (Mrp3). Overall, these findings indicate that NML and OBA may alleviate NASH and liver fibrosis in mice via enhancing antioxidant and anti-inflammation capacity. Our study proposed that NML and OBA may be potential strategies for NASH treatment.

The mechanisms of metabolic resistance to pyrethroids and neonicotinoids fade away without selection pressure in the tarnished plant bug Lygus lineolaris.

Heavy selection pressure prompted the development of resistance in a serious cotton pest tarnished plant bug (TPB), Lygus Lineolaris in the mid-southern USA. Conversely, a laboratory resistant TPB strain lost its resistance to five pyrethroids and two neonicotinoids after 36 generations without exposure to any insecticide. It is worthwhile to examine why the resistance diminished in this population and determine whether the resistance fade away has practical value for insecticide resistance management in TPB populations. A field-collected resistant TPB population in July (Field-R1) exhibited 3.90-14.37-fold resistance to five pyrethroids and two neonicotinoids, while another field-collected TPB population in April (Field-R2) showed much lower levels of resistance (0.84-3.78-fold) due to the absence of selection pressure. Interestingly, after 36 generations without exposure to insecticide, the resistance levels in the same population (lab-R) significantly decreased to 0.80-2.09-fold. The use of detoxification enzyme inhibitors had synergistic effects on permethrin, bifenthrin and imidacloprid in resistant populations of L. lineolaris. The synergism was more pronounced in field-R2 than lab-S and lab-R TPB population. Moreover, esterase, GST, and P450 enzyme activities increased significantly by approximately 1.92-, 1.43-, and 1.44- fold in field-R1, respectively, and 1.38-fold increased P450 enzyme activities in field-R2 TPB population, compared to the lab susceptible (lab-S) TPB. In contrast, the three enzyme activities in the lab-R strain were not significantly elevated anymore relative to the lab-S population. Additionally, field-R1 TPB showed elevated expression levels of certain esterase, GST and P450 genes, respectively, while field-R2 TPB overexpressed only P450 genes. The elevation of these gene expression levels in lab-R expectedly diminished to levels close to those of the lab susceptible (lab-S) TPB populations. Our results indicated that the major mechanism of resistance in TPB populations was metabolic detoxification, and the resistance development was likely conferred by increased gene expressions of esterase, GST, and P450 genes, the fadeaway of the resistance may be caused by reversing the overexpression of esterase, GST and P450. Without pesticide selection, resistant gene (esterase, GST, P450s) frequencies declined, and detoxification enzyme activities returned to lab-S level, which resulted in the recovery of the susceptibility in the resistant TPB populations. Therefore, pest's self-purging of insecticide resistance becomes strategically desirable for managing resistance in pest populations. This article is protected by copyright. All rights reserved.

Abstract 73: Specific Activity of GSTs and Protein Expression of GSTT1, GSTP1 and CYP1A1 in Head and Neck Cancer

Abstract Purpose: Rising incidence of head and neck cancer have been observed in developing countries over last decade. It has been postulated that carcinogen detoxifying genes may be involved directly or indirectly in pathogenesis of head and neck cancer. Three genes (CYP1A1, GSTM1 and GSTP1) were studied for their association with head and neck cancer. Cytochrome P450 1A1 (CYP1A1) is phase I enzyme while glutathione S transferases (GSTs) constitute the phase II detoxification enzymes. Abnormal protein expression of CYP1A1 and GSTs lead to cancer initiation. Methods: The current case control study was designed to evaluate the possible associations of these enzymes with head and neck cancer. Serum GSTs activity was determined by using ELISA and CYP1A1, GSTT1, GSTP1 expression in tissue by immunohistochemistry with specific antibodies. Results: Mean serum GSTs specific activity was 7.7 (+11.5)U/L and control was 11.4 (+7.5)U/L. Significant decrease (P&amp;lt;0.05) in GSTs specific activity was observed in head and neck cancer patients compared to controls (P&amp;lt;0.001). Moreover, CYP1A1 and GSTT1 was down expressed whereas GSTP1 was over expressed in head and neck cancer tissues compared with adjacent normal control tissue. Conclusion: Conclusion: Decreased activity of GSTs, reduced expression of GSTs, CYP1A1, GSTT1 and increased expression of GSTP1 may contribute to head and neck cancer development in Pakistani population. Citation Format: Nosheen Masood, Azra Yasmin. Specific Activity of GSTs and Protein Expression of GSTT1, GSTP1 and CYP1A1 in Head and Neck Cancer [abstract]. In: Proceedings of the 11th Annual Symposium on Global Cancer Research; Closing the Research-to-Implementation Gap; 2023 Apr 4-6. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(6_Suppl):Abstract nr 73.

Receptor-Like Cytoplasmic Kinase STK Confers Salt Tolerance in Rice

BackgroundSoil salinization is a major abiotic environmental stress factor threatening crop production throughout the world. Salt stress drastically affects the growth, development, and grain yield of rice (Oryza sativa L.), and the improvement of rice tolerance to salt stress is a desirable approach for meeting increasing food demand. Receptor-like cytoplasmic kinases (RLCKs) play essential roles in plant growth, development and responses to environmental stresses. However, little is known about their functions in salt stress. Previous reports have demonstrated that overexpression of an RLCK gene SALT TOLERANCE KINASE (STK) enhances salt tolerance in rice, and that STK may regulate the expression of GST (Glutathione S-transferase) genes.ResultsThe expression of STK was rapidly induced by ABA. STK was highest expressed in the stem at the heading stage. STK was localized at the plasma membrane. Overexpression of STK in rice increased tolerance to salt stress and oxidative stress by increasing ROS scavenging ability and ABA sensitivity. In contrast, CRISPR/Cas9-mediated knockout of STK increased the sensitivity of rice to salt stress and oxidative stress. Transcriptome sequencing analysis suggested that STK increased the expression of GST genes (LOC_Os03g17480, LOC_Os10g38140 and LOC_Os10g38710) under salt stress. Reverse transcription quantitative PCR (RT-qPCR) suggested that four stress-related genes may be regulated by STK including OsABAR1, Os3BGlu6, OSBZ8 and OsSIK1.ConclusionsThese findings suggest that STK plays a positive regulatory role in salt stress tolerance by inducing antioxidant defense and associated with the ABA signaling pathway in rice.

Transcription Factor AhR Regulates Glutathione S-Transferases Conferring Resistance to lambda-Cyhalothrin in Cydia pomonella.

Aryl hydrocarbon receptor (AhR) enhances insect resistance to insecticides by regulating the detoxification network. Our previous studies have confirmed that overexpressions of cytochrome P450 monooxygenases (P450s) and glutathione S-transferases (GSTs) are involved in lambda-cyhalothrin resistance in Cydia pomonella. Here, we report that CpAhR regulates the expression of GST and P450 genes, thus conferring resistance. Expression patterns indicated that the expression of CpAhR was highly induced by lambda-cyhalothrin exposure and upregulated in a lambda-cyhalothrin-resistant population. RNA interference (RNAi) of CpAhR decreases the expression of key resistance-related genes (CpGSTe3, CpCYP9A121, and CpCYP9A122) and the activity of the GST enzyme, reducing the tolerance to lambda-cyhalothrin. Furthermore, β-naphthoflavone, a novel agonist of AhR, was first proven to be effective in increasing CpAhR expression and larval tolerance to lambda-cyhalothrin. These results demonstrate that CpAhR regulates the expression of key detoxifying genes and GST activity, resulting in the development of resistance to lambda-cyhalothrin in C. pomonella.

Transcriptomic and physiological properties reveal the tolerance mechanism to difenoconazole toxicity in wheat (Triticum aestivum L.)

Difenoconazole (DFZ) is a broad-spectrum fungicide widely applied in wheat production. However, excessive accumulation is linked to phytotoxicity. The effects of DFZ on plants and the response mechanisms to DFZ toxicity are poorly understood. Herein, the uptake, accumulation, and translocation of DFZ and induced changes in the morphology, physiology, and gene expression were investigated under hydroculture of roots treated with 50, 100, and 200 mg/L DFZ concentrations. Compared with the control, DEZ treatment upregulated the expression of genes encoding 4-coumarate-CoA ligase (4CL) and peroxidase (POD) involved in the lignin biosynthesis pathway and enhanced lignin biosynthesis. DFZ accumulated more in older leaves (cotyledons and lower true leaves), with 0.49–5.71 and 0.09–2.14 folds higher than levels in new upper leaves and roots, respectively. The excessive accumulation of DFZ in tissues was rapidly degraded, with a 15.7–69.3% reduction of DFZ content in roots and leaves from 3 DAT to 6 DAT. The genes expression and activity of glutathione S-transferase (GST) were increased. Furthermore, DFZ treatments upregulated genes encoding chalcone synthase (CHS), chalcone isomerase (CHI), and anthocyanidin synthase (ANS) involved in the flavonoid biosynthesis pathway and increased the amount of flavonoid and anthocyanins in leaves. This study provides new insights into the self-protective behaviors exhibited by wheat plants under DFZ stress. The mechanisms included hindering DFZ penetration from roots by enhancing lignin biosynthesis, accumulating more in old leaves, degrading by GST, and alleviating oxidative damage by increasing the content of flavonoids and anthocyanins in leaves.

Relation among Mercury, Selenium, and Biomarkers of Oxidative Stress in Northern Pike (Esox lucius).

Mercury (Hg) is a toxic environmental contaminant associated with oxidative stress in freshwater fish. A known antagonist to Hg, selenium (Se), may reduce the toxic effects of Hg. In this study, the relation among Se, methylmercury (MeHg), inorganic mercury (IHg), total mercury (THg), and the expression of biomarkers of oxidative stress and metal regulation in livers of northern pike were examined. Livers from northern pike were collected from 12 lakes in Isle Royale National Park, Pictured Rocks National Lakeshore, Sleeping Bear Dunes National Lakeshore, and Voyageurs National Park. The concentrations of MeHg, THg, and Se were measured in liver tissue, and the expression of superoxide dismutase (sod), catalase (cat), glutathione s-transferase (gst), and metallothionein (mt) was assessed. There was a positive relationship between the concentrations of THg and Se, with a Hg:Se molar ratio less than one in all livers examined. There was no significant relation between sod, cat, gst, or mt expression and Hg:Se molar ratios. cat and sod expression were significantly related to increases in percent MeHg, relative to THg; however, gst and mt expression were not significantly altered. This suggests that incorporating biomarkers containing Se may be a better indicator than non-selenium-containing proteins of assessing the long-term effect of Hg and the interactions between Hg and Se in the livers of fish, such as northern pike, especially when molar concentrations of Se are greater than Hg.