• Archives of Pharmacal Research
• /
• v.27 no.7
• /
• pp.757-762
• /
• 2004

The protective adaptive response to electrophiles and reactive oxygen species is mediated by the induction of phase II detoxifying genes including glutathione S-transferases (GSTs). NF-E2-related factor-2 (Nrf2) phosphorylation by protein kinase C (PKC) is a critical event for its nuclear translocation in response to oxidative stress. Previously, we have shown that peroxynitrite plays a role in activation of Nrf2 and Nrf2 binding to the antioxidant response element (ARE) via the pathway of phosphatidylinositol 3-kinase (PI3-kinase) and that nitric oxide synthase in hepatocytes is required for GSTA2 induction. In view of the importance of PKC and Pl3-kinase in Nrf2-mediated GST induction, we investigated the role of these kinases in peroxynitrite formation for GSTA2 induction by oxidative stress and determined the relationship between PKC and PI3-kinase. Although PKC activation by phorbol 12-myristate-13-acetate (PMA) did not increase the extents of constitutive and inducible GSTA2 expression, either PKC depletion by PMA or PKC inhibition by staurosporine significantly inhibited GSTA2 induction by tert-butylhydroquinone (t-SHa) a prooxidant chemical. Therefore, the basal PKC activity is req- uisite for GSTA2 induction. 3-Morpholinosydnonimine (SIN-1), which decomposes and yields peroxynitrite, induced GSTA2, which was not inhibited by PKC depletion, but slightly enhanced by PKC activation, suggesting that PKC promotes peroxynitrite formation for Nrf2-mediated GSTA2 induction. Treatment of cells with S-nitroso-N-acetyl-penicillamine (SNAP), an exogenous NO donor, in combination with t-BHQ may produce peroxynitrite. GSTA2 induction by SNAP ＋ t-BHQ was not decreased by PKC depletion, but rather enhanced by PKC activation, showing that the activity of PKC might be required for peroxynitrite formation. LY294002 a P13-kinase inhibitor blocked GSTA2 induction by t-BHQ, which was reversed by PMA-induced PKC activation. These results provide evidence that PKC may playa role in formation of peroxynitrite that activates Nrf2 for GSTA2 induction and that PKC may serve an activator for GSTA2 induction downstream of PI3-kinase.

• Parasites, Hosts and Diseases
• /
• v.62 no.2
• /
• pp.205-216
• /
• 2024

Sigma-class glutathione transferase (GST) proteins with dual GST and prostaglandin synthase (PGS) activities play a crucial role in the establishment of Clonorchis sinensis infection. Herein, we analyzed the structural and enzymatic properties of sigma-class GST (CsGST-σ) proteins to obtain insight into their antioxidant and immunomodulatory functions in comparison with mu-class GST (CsGST-µ) proteins. CsGST-σ proteins conserved characteristic structures, which had been described in mammalian hematopoietic prostaglandin D₂ synthases. Recombinant forms of these CsGST-σ and CsGST-µ proteins expressed in Escherichia coli exhibited considerable degrees of GST and PGS activities with substantially different specific activities. All recombinant proteins displayed higher affinities toward prostaglandin H₂ (PGS substrate; average K_m of 30.7 and 3.0 ㎛ for prostaglandin D₂ [PGDS] and E₂ synthase [PGES], respectively) than those toward CDNB (GST substrate; average K_m of 1,205.1 ㎛). Furthermore, the catalytic efficiency (K_cat/K_m) of the PGDS/PGES activity was higher than that of GST activity (average K_cat/K_m of 3.1, 0.7, and 7.0×10^-3 s^-1㎛^-1 for PGDS, PGES, and GST, respectively). Our data strongly suggest that the C. sinensis sigma- and mu-class GST proteins are deeply involved in regulating host immune responses by generating PGD₂ and PGE₂ in addition to their roles in general detoxification.

• Journal of Yeungnam Medical Science
• /
• v.12 no.1
• /
• pp.32-47
• /
• 1995

Glutathione(GSH) has a very important role in detoxification of cells and is closely related to antitumor drug-resistance of cancer cells. In order to evaluate the importance of glutathione metabolism in the drug-resistant cancer cells, the concentration of celluar GSH and activities of ${\gamma}$-glutamylcysteine synthetase(GCS), ${\gamma}$-glutamyl transpeptidase (GGT) and glutathione S-transferases(GST) in the adriamycin, vincristine, or cisplatin resistant L1210 (L1210AdR, L1210VcR, or L1210Cis) sublines were measured. Expression and amplification of GCS, GGT, and GST-${\pi}$ genes were also observed in the parent Ll210 and the drug-resistant Ll210 sublines. The concentration of GSH was increased 5.34 fold in L1210Cis, 2.83 fold in L1210VcR, and 1.78 fold in L1210AdR, compared to L1210. The activities of GCS and GGT were increased in drug-resistant L1210 sublines. The GST activity was increased in L1210VcR and L1210Cis but decreased in L1210AdR compared to Ll210. Expression of GCS, GGT, and GST-${\pi}$ genes were increased in the resistant L1210 sublines compare to the parent L1210 in northern blot analyses. Overexpression of GCS, GGT, and GST-${\pi}$ were observed in the resistant sublines, and the increases of the concentration of glutathione and the activities of GCS and GGT in the resistant sublines may be involved in a part of the drug-resistance in the resistant sublines.

• Asian-Australasian Journal of Animal Sciences
• /
• v.24 no.12
• /
• pp.1681-1689
• /
• 2011

The beneficial effects of tea catechins (TCs) are related not only to their antioxidant potential but also to the improvement of animal meat quality. In this study, we assessed the effects of dietary TC supplementation on plasma biochemical parameters, hormone responses, and glutathione redox status in goats. Forty Liuyang goats were randomly divided into four equal groups (10 animals/group) that were assigned to four experimental diets with TC supplementation at 4 levels (0, 2,000, 3,000 or 4,000 mg TC/kg DM feed). After a 60-day feeding trial, all goats were slaughtered and sampled. Dietary TC treatment had no significant effect on blood biochemical parameters, however, low-density lipoprotein cholesterol (p<0.001), triglyceride (p<0.01), plasma urea nitrogen (p<0.01), and glucose (p<0.001) decreased and total protein (p<0.01) and albumin (p<0.05) increased with the feeding time extension, and day 20 was the turning point for most of changes. Interactions were found in glutathione (p<0.001) and the ratio of reduced and oxidized glutathione (p<0.05) in whole blood between treatment and feeding time. Oxidized glutathione in blood was reduced (p<0.05) by 2,000 mg TC/kg feed supplementation, and a similar result was observed in longissimus dorsi muscle. Though plasma glutathione peroxidase (p<0.01) and glutathione reductase (p<0.05) activities were affected by treatment and feeding time interactions, and glutathione S-transferases activity increased with feeding day extension, no changed values appeared in longissimus dorsi muscle. In conclusion, dietary TC supplementation affected the concentrations of some blood metabolites and accelerated GSH depletion in the blood of goats. In terms of less high-density lipoprotein cholesterol, the highest insulin and IGF-I concentrations, the highest ratio of reduced and oxidized glutathione in plasma, the dosage of 2,000 mg TC/kg feed might be desirable for growing goats to prevent glutathione depletion and keep normal physiological metabolism.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.1
• /
• pp.69-73
• /
• 2012

Cancer is a complex disease and the genetic susceptibility to it could be an outcome of the inherited difference in the capacity of xenobiotic metabolizing enzymes. Glutathione-S-transferases (GSTs) are phase II metabolizing enzymes whose various genotypes have been associated with increased risk of different types of cancer. Null mutations caused by the deletion of the entire gene result in the absence of the enzymatic activity and increase in the risk of developing cancer including chronic myeloid leukaemia (CML). In the present case-control study we evaluated the effect of null mutations in GSTM1 and GSTT1 genes on the risk of developing CML. The study included 75 CML patients (43 males and 32 females; age (mean ${\pm}$ S.D) $42.3{\pm}13.4$ years) and unrelated non-malignant controls (76 male and 48 females; age (mean ${\pm}$ S.D) $41.5{\pm}12.9$). The distribution of GSTM1 and GSTT1 genotypes in CML patients and controls was assessed by multiplex-PCR method. Logistic regression was used to assess the relationship between GSTM1 and GSTT1 genotypes and risk of CML. Chi-square test was used to evaluate the trend in modulating the risk to CML by one or more potential high risk genotype. Although GSTM1 null genotype frequency was higher in CML patients (41%) than in the controls (35%), it did not reached a statistical significance (OD = 1.32, 95% CI: 0.73-2.40; P value = 0.4295). The frequency of GSTT1 null genotypes was higher in the CML patients (36%) than in the controls (21%) and the difference was found to be statistically significant (OD = 2.12, 95% CI: 1.12-4.02; P value = 0.0308). This suggests that the presence of GSTT1genotype may have protective role against the CML. We found a statistically significant (OD = 3.09, 95% CI: 1.122-8.528; P value = 0.0472) interaction between the GSTM1 and GSTT1 null genotypes and thus individuals carrying null genotypes of both GSTM1 and GSTT1 genes are at elevated risk of CML.

• Korean Journal of Clinical Laboratory Science
• /
• v.52 no.2
• /
• pp.136-142
• /
• 2020

The antimicrobial resistance rate in bacteria has increased over the last several decades. The transfer of antimicrobial resistant determinants on mobile genetic elements could cause the accelerated emergence and spread of multidrug resistant bacteria. This study investigated the aminoglycoside resistance determinants transferred by mobile genetic elements in a total of 33 aminoglycoside non-susceptible E. coli isolated from clinical specimens in Chungcheong province. 16S ribosomal RNA methyl-transferases (RMTases) and aminoglycoside-modifying enzyme (AME) genes were detected via PCR and DNA sequencing. The most common AME genes were aac(3')-II gene (54.5%), followed by aph(3')-Ia (18.2%) and aac(6')-Ib (15.2%). None of the evaluated RMTase genes were detected in the 33 isolates. Seventeen of the 18 isolates harboring aac(3')-II gene were resistant to gentamicin, and 16 of them were resistant to tobramycin. The 5 isolates harboring aac(6')-Ib gene were all resistant to tobramycin. In this study, we confirmed that one of the important mechanisms of aminoglycoside resistance in E. coli isolated from human is the acquisition of AME genes. Continuing investigations of antimicrobial resistant determinants in bacteria isolated from human may be required to prevent dissemination of antimicrobial resistant bacteria.

• The Korean Journal of Malacology
• /
• v.30 no.4
• /
• pp.399-408
• /
• 2014

Glutathione S-transferases (GSTs) are a superfamily of detoxification enzymes that primarily catalyze the nucleophilic addition of reduced glutathione to both endogenous and exogenous electrophiles. In this study, we isolated and characterized a full-length of alpha class GST cDNA from the abalone (Haliotis discus hannai). The abalone GST cDNA encodes a 223-amino acid polypeptide with a calculated molecular mass of 25.8 kDa and isoelectric point of 5.69. Multiple alignments and phylogenetic analysis with the deduced abalone GST protein revealed that it belongs to the alpha class GSTs and showed strong homology with disk abalone (Haliotis discus discus) putative alpha class GST. Abalone GST mRNA was ubiquitously detected in all tested tissues. GST mRNA expression was comparatively high in the mantle, gill, liver, and digestive duct, however, lowest in the hemocytes. Expression level of abalone GST mRNA in the mantle, gill, liver, and digestive duct was 182.7-fold, 114.8-fold, 4675.8-fold, 406.1-fold higher than in the hemocytes, respectively. Expression level of abalone GST mRNA in the liver was peaked at 6 h post-infection with Vibrio parahemolyticus and decreased at 12 h post-infection. While the expression level of abalone GST mRNA in the hemocytes was drastically increased at 3 h post-infection with Vibrio parahemolyticus. These results suggest that abalone GST is conserved through evolution and may play roles similar to its mammalian counterparts.

• Korean Journal of Head & Neck Oncology
• /
• v.18 no.2
• /
• pp.150-156
• /
• 2002

Objectives: Most of human cancers may result from exposure to environmental carcinogens, and individual effectiveness in the detoxification of these chemicals will influence susceptibility to malignant disease. Glutathione S-Transferases(GSTs) enzymes are involved in the detoxification of active metabolites of many carcinogens from tobacco smoke and may be important in modulating susceptibility to smoke-related cancer. The purpose of this study is to determine the polymorphism of GSTM1, GSTT1, and GSTP1 in control group and head and neck squamous cell carcinoma group of Korean, and to investigate the effect of GSTs polymorphism on the risk of head and neck cancer. Materials and Methods: A hospital-based case-control study was performed with a group of 133 control individual and 136 head and neck squamous cell carcinoma patients. The polymorphisms of GSTs were analysed using polymerase chain reaction in GSTM1 and GSTTl, and polymerase chain reaction-restriction fragment length polymorphism in GSTP1. Results: The relative risk (odds ratio) of GSTM(-) genotype was 1.14(95% CI, 0.70-1.85) compared to GSTM1(+). The odds ratio of GSTTl(-) genotype was 0.91(95% CI, 0.55-1.50). In old age($65$) group, the odds ratio of GSTT1(-) genotype was 5.2(95% CI, 1.53-17.89). The GSTP1 Val/Val genotype conferred a 1.7-fold risk(95% CI, 0.40-7.34) of head and neck cancer compared with GSTP1 Ile/Ile genotype. Among the combined genotypes of GSTs, GSTM1(-)/GSTT1(+)/GSTP1 Val/Val and GSTM1(-)/GSTTl(-)/GSTP1 Ile/Val genotypes conferred a 2.6-fold and 1.3-fold risk(95% CI, 0.24-14.15 and 0.43-3.14) compared with the GSTM1(+)/GSTTl(+)/GSTP1 Ile/Ile genotype, respectively. Conclusion: Polymorphism of GSTs might modulate susceptibility to head and neck cancer in Korean population. The genotype of GSTP1 Val/Val and combined genotypes of GSTM1(-)/GSTT1(+)/GSTP1 Val/Val, and GSTM1(-)/GSTT1(-)/GSTP1 Ile/Val might be important risk factors to determine the individual susceptibility to head and neck squamous cell carcinoma.

• Toxicological Research
• /
• v.14 no.3
• /
• pp.293-300
• /
• 1998

Previous studies have shown that the heterocycles including thiazoles are efficacious in inducing phase phase II metabolizing enzyme as well as certain cytochrome P450s and that the inductin of these matabolizing enzymes by the heterocyclic agents is highly associated with their hepatotoxicity. In the present study, the effects of benzylisothiazole (BIT), which has a isothiazole moiety, on the expression of microsomal epoxide hydrolase (mEH), major glutathione S-transerases and cytochrome P450s were studied in the rat liver in association with its hepatotoxicity. Treatment of rats with BIT(1.17 mmol/kg, 1~3d) resulted in substantial increases in the mEH. rGSTA2, rGSTA2, rGSTM1 and rGSTM2 mRNA levels, whereas rGSTA3 and rGSTA5 mRNA levels were increased to much lesser extents. A time-course study showed that the mRNA levels of mEH and rGSTs were greater at 24hr after treatment than those after 3 days of consecutive treatment. Relative changes in mEH and rGST mRNA levels were consistent with those in the proteins, as assessed by Western immunoblot analysis. Hepatic cytochrom P450 levels were monitored after BIT treatment under the assumption that metabolic activation of BIT may affect expression of the enzymes in conjunction with hepatotoxicity. Immunoblot analysis revealed that cytochrome P450 2B1/2 were 3-to 4-fold induced in rats teatd with BIT(1.17 mmol/kg/day.3days), whereas P450 1A2, 2C11 and 3A1/2 levels were decreased to 20~30% of those in unteatd rats. P450 2E1 was only slightly decreased by BIT. Thus, the levels of several cytochrome P450s were suppressed by BIT treatment. Rats treated with BIT at the dose of 1.17mmol/kg for 3 days exhibited extensive multifocal nodular necrosis with moderate to extensive diffuse liver cell degeneration. No notable toxicity was observed in the kidney. These results showed that BIT induces mEH and rGSTs in the liver with increases in the mRNA levels, whereas the agent significantly decreased major cytochrome P450s. The changes in the detoxifying enzymes might be associated with the necrotic liver after consecutive treatment.

• Journal of Bio-Environment Control
• /
• v.11 no.3
• /
• pp.139-143
• /
• 2002

Cotton Glutathione S-Transferase (GST: EC 2.5.1.18) was cloned and overexpressed in tobacco (Nicotiana tabacum) plants. Northern blot analysis confirmed the successful transformation of cotton gst gene in tobacco plant. Type I and Type ll transcript patterns were identified in transgenic tobacco plants and only Type I transcripts were discussed in this paper, The activity of GST in the type II transgenic plants was about 1.5-fold higher than those of the wild type and non-expresser by using 1-chloro-2,4-dinitrobenzene (CDNB) and reduced glutathione as the substrate. The expression of cotton GST in tobacco plants proved that Gh-5 could be translated into functional protein. Type II transgenic plants produced functional GST in the cells. The effects of cotton GST in the seedlings was evaluated by growing the control and transgenic seedlings at $15^{\circ}C$ in the growth chamber in the light. Overexpressors were grown well compared to the control plants (non-expressors). lo test far tolerance to salinity, seeds of Gh-5 overexpressors and the wild type Xanthi seedlings were grown at 0, 50, 100, 150, and 200 mM NaCl solution. Gh-5 transgenic seedlings showed higher growth rate over control seedlings on 50 and 100 mM NaCl solution. There was no difference in growth rate at 150 and 200mM NaCl concentration.