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Overexpression of cellular glutathione peroxidase does not affect expression of plasma glutathione peroxidase or phospholipid hydroperoxide glutathione peroxidase in mice offered diets adequate or deficient in selenium.

Selenium-dependent cellular glutathione peroxidase (GPX1) overexpressing [GPX1(+)] mice were derived by microinjecting a 5.3-kb cloned entire mouse GPX1 genomic DNA into fertilized eggs. The objective of this study was to determine the effect of GPX1 overexpression and dietary selenium on the expression of selenoperoxidases and the status of lipid peroxidation of these transgenic animals. An experiment with a 2 x 2 factorial arrangement of treatments with 15 GPX1(+) and 15 control mice (2 mo old) was conducted for 8 wk. Ten mice of each group (half males and females) were fed a Se-deficient, Torula yeast basal diet (0.02 mg Se/kg, no supplemental vitamin E) and five mice (three males and two females) were fed the basal diet supplemented with 0.51 mg Se/kg as Na2SeO3. The GPX1(+) mice had greater GPX1 activities (one- to sixfold, P < 0.0001) than the control mice at both levels of dietary selenium in all tissues except for liver, in which such difference (100%, P < 0.05) was observed only in Se-deficient mice. The GPX1 mRNA level in kidney and in lung of the Se-deficient GPX1(+) mice was 81% and 7.5-fold greater (P < 0.003) than the respective control level. Overexpression of GPX1 did not alter phospholipid hydroperoxide glutathione peroxidase (GPX4) activities and mRNA levels or glutathione S-transferase (GST) activities in most of the tissues, plasma glutathione peroxidase (GPX3) activity or plasma Se concentrations. No differences in lipid peroxidation in kidney, lung or intestine were observed between the Se-deficient GPX1(+) and control mice. In conclusion, the overexpression of the GPX1 gene in these mice was tissue specific and did not affect the expression of GPX3, GPX4 or GST and plasma Se levels; dietary Se appeared to affect the GPX1 overexpression at its mRNA level.

Animals↗

Changes in glutathione, glutathione reductase and glutathione-S-transferase as a function of cell concentration and age.

The activities of glutathione-S-transferase (GST) and glutathione reductase (GSR) in mouse lymphocytes as a function of cell concentration and age were determined. Lymphocytes from 2-, 9- and 24-month-old mice were isolated and the activity of GST was determined spectrophotometrically using 1-chloro-2,4-dinitrobenzene as the substrate. Lymphocyte concentrations of 0.44, 0.75 and 0.55 X 10(6) cells/ml were found to be optimal for assaying GST in 2-, 9- and 24-month-old mice, respectively. Determination of GSR activity was based on NADPH reduction of oxidized glutathione and cell concentrations of 0.29, 0.30 and 0.22 X 10(6) cells/ml were chosen for assaying the enzyme activity for the three age groups, respectively. Glutathione levels and GSR activity of mice lymphocytes were higher in 2- and 24-month-old mice as compared to 9-month-old animals. However, GST activity of mouse lymphocytes was low in 2- and 9-month-old mice and increased significantly in 24-month-old animals.

Aging↗

Abiotic stress alters transcript profiles and activity of glutathione S-transferase, glutathione peroxidase, and glutathione reductase in Euphorbia esula.

Glutathione S-transferase (GST), glutathione peroxidase (GPX), and glutathione reductase (GR) are enzymes that utilize glutathione to play an important role in plant defense mechanisms. In leafy spurge (Euphorbia esula L.), transcript and activity profiles for these enzymes are differentially influenced in tissue exposed to xenobiotic (diclofop-methyl) and environmental stress (cold and drought). Five different EeGST cDNA (including phi, tau, theta, and zeta class GSTs), one EeGPX cDNA, and one EeGR cDNA showed differential expression patterns in leafy spurge plants exposed to diclofop-methyl-, cold- and drought-stress. Tissue treated with diclofop-methyl also had increased GST, GPX and GR activities that were preceded or paralleled by increased gene expression. Transcript profiles resulting from drought-stressed plants were similar to transcript profiles from diclofop-methyl-treated plants but not cold-stressed plants. GPX activity in leafy spurge protein extracts was not bound to either S-hexylglutathione- or glutathione-agarose columns but instead co-migrated with fractions of GST activity that also were not bound by affinity chromatography. Fractions of GST proteins that were bound to S-hexylglutathione revealed that increased GST activity in diclofop-methyl-treated tissue could be identified as phi- and tau-type GSTs.

Journal Article↗

Glutathione peroxidase, glutathione S-transferase and glutathione reductase activities in normal and neoplastic human breast tissue.

Glutathione peroxidase (GSH-Px), glutathione S-transferase (GSH-Tr) and glutathione reductase (GSSG-Rx) activities have been determined in normal and neoplastic human breast tissues. Large interindividual variations in the activities of all enzymes tested were found in both tumor and non-tumor specimens. In general a significant increase in the activities of the 3 enzymes was found in tumors, whereas in fibroadenoma they were as high as in healthy tissues. When a comparison was made between normal and neoplastic tissues of the same individual, GSH-Tr and GSSG-Rx activities were found to be higher in 15 and 11 cases, respectively, out of 17. GSG-Px activity was higher in all cases. From measurement of GSG-Px activity with both H202 and cumene hydroperoxide, it was deduced that human breast contains only the selenium-dependent form.

Adenofibroma↗

Changes of reduced glutathion, glutathion reductase, and glutathione peroxidase after radiation in guinea pigs.

In this series of experiments the protective action of reduced glutathion due to ionizing radiation has been studied. In the experimental group 18 guinea pigs were exposed to successive radiations of 150 rad 3 or 4 days apart. Total dose given amounted to 750 rad which is the LD50 for guinea pigs. Blood samples were taken 30 min after each exposure. The control series were sham radiated but otherwise treated identically. The cells of the removed blood samples were separated by centrifugation and were subjected to the reduced glutathion stability test. GSSGR, GPer, and LDH enzyme activities were also measured of which the latter served as a marked enzyme. It was found that LDH did not show any alteration after radiation. The reduced glutathion stability test showed a consistent but minor reduction (P greater than 0.05), in the experimental group. GSSGR enzyme activity on the other hand was reduced significantly (from 176.48 +/- 11.32 to 41.34 +/- 1.17 IU/ml of packed erythrocytes, P less than 0.001) in the same group. GPer activity showed a consistent but minor elevation during the early phase of the experimental group. It was later increased significantly beginning after 600 rad total radiation on the fourth session (P less than 0.050).

Animals↗

Glutathione peroxidase, glutathione-S-transferase, catalase, xanthine oxidase, Cu-Zn superoxide dismutase activities, total glutathione, nitric oxide, and malondialdehyde levels in erythrocytes of patients with small cell and non-small cell lung cancer.

Lung cancer is a common pathology with high mortality due to late diagnosis. Glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST), catalase (CAT), xanthine oxidase (XO), Cu-Zn superoxide dismutase (Cu-Zn SOD) activities, total glutathione (TGSH), nitric oxide (NO*), and malondialdehyde (MDA) levels were investigated in erythrocytes of patients with non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC), and healthy control group. We aimed to investigate serum GSH, GSH-dependent enzymes activities (GSH-Px and GST), XO, CAT, Cu-Zn SOD activity, and NO*, and MDA levels in patients with NSCLC and with SCLC and correlate with the cancer stage. Erythrocyte MDA, NO*, TGSH levels and erythrocyte SOD, CAT and XO activities were significantly higher in patients with NSCLC and SCLC than in controls. Slightly increased erythrocyte GSH-Px and GST activities were not significantly different from the controls. Erythrocyte MDA level positively correlated with erythrocyte NO* levels in patients with early stage (I+II) in NSCLC groups. Erythrocyte MDA level positively correlated with erythrocyte XO activity in patients with advanced stage (III+IV) in NSCLC groups. However, no other correlation could be found among the parameters in healthy controls and patients with NSCLC and with SCLC. Results obtained in this study indicate significant changes in antioxidant defence system in NSCLC and SCLC patients, which may lead to enhanced action of oxygen radical, resulting in lipid peroxidation.

Adult↗

Glutathione peroxidase, glutathione reductase, Cu-Zn superoxide dismutase activities, glutathione, nitric oxide, and malondialdehyde concentrations in serum of patients with chronic lymphocytic leukemia.

BACKGROUND: Chronic lymphocytic leukemia (CLL) is a rare neoplasm that comprises a substantial proportion of all leukemias in middle-aged persons and is the most common type among elderly persons. The major causes are not known nor is there a detailed understanding about how the elusive origin(s) may relate to clinical expression, basic biological mechanisms, or pathogenesis. METHODS: Glutathione peroxidase (GSH-Px), glutathione reductase (GRD), Cu-Zn superoxide dismutase (Cu-Zn SOD) activities, glutathione (GSH), nitric oxide (NO(*), and malondialdehyde (MDA) concentrations were measured in serum of patients with CLL and a healthy control group. RESULTS: Serum GSH-Px, Cu-Zn SOD activities, GSH concentration were lower in patients with CLL while serum NO(*) and MDA concentrations were higher in these patients compared with the control group. Serum GRD activity was not statistically significant in patients with CLL compared with the control. However, there was no statistically significant difference in the parameters on the basis of stages in these patients. Serum GSH concentration negatively correlated with serum MDA (r=30.63, p<0.05) and NO(*) concentrations (r=0.72, p<0.05) in patients with advanced stage (III+IV). However, no other correlation could be found among the parameters in healthy controls and patients with CLL CONCLUSIONS: There is significant changes in antioxidant defense system in CLL cases, which may lead to enhanced action of oxygen radical, resulting in lipid peroxidation.

Adult↗

Cellular balance of glutathione levels through the expression of gamma-glutamylcysteine synthetase and glutathione thiol transferase genes in human hepatic cells resistant to a glutathione poison.

Buthionine sulfoximine (BSO) is a synthetic amino acid that irreversibly inhibits glutathione biosynthesis and deranges reduced glutathione (GSH) metabolism in liver cells. We isolated two BSO-resistant lines, HLE/BSO2-1 and HLE/BSO2-2, from human hepatic HLE/WT cells. Cellular levels of the Pi class glutathione thiol transferase (GSTP1) were 3-fold lower in BSO-resistant lines than in HLE/WT cells. By contrast, gamma-glutamylcysteine synthetase (GCS) heavy subunit (GCSh) mRNA levels were markedly decreased in HLE/BSO2-1 and HLE/BSO2-2 as compared with HLE/WT. The expression of a dominant-negative mutant of c-Jun inhibited the GCSh promoter activity in HLE/WT, but not in HLE/BSO2-1. Cellular levels of AP-1, however, were not decreased in either BSO-resistant cell line. Transfection of GCSh promoter of various lengths driven reporter constructs showed no sequence-specific increase in the promoter activities in HLE/BSO2-1. However, transfection of GSTP1 cDNA into HLE/BSO2-1 and HLE/BSO2-2 restored the levels of GCSh mRNA and the GCSh promoter activity to those of HLE/WT. Sequences between -315 and -241 bp of the 5' region contained an AP-1 site responsible for the enhanced GCSh promoter activity in GSTP1 transfectants of HLE/BSO2-1. In vivo footprint analysis showed a specific protection of the AP-1 site on GCSh promoter in GSTP1 transfected HLE/BSO2-1. GSH homeostasis thus appears to be maintained by an interaction between GSTP1 and GCS in human hepatic cells resistant to the GSH poison.

Buthionine Sulfoximine↗

Effect of storage temperature on the activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione S-transferase in rat liver and kidney homogenates.

The behavior of the catalytic activities of the enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase and glutathione reductase was tested in rat liver and kidney homogenates stored at 4, -20 and -70 degrees C and in corresponding tissue samples stored at -70 degrees C. The stabilities of enzymes were different for various enzymes and were dependent on the organ (liver, kidney) and the storage temperature. The storage temperature of -70 degrees C guaranteed the best stability and the five enzymes investigated were sufficiently stable in preserved tissue samples or in homogenates prepared with conventional mannit/sucrose homogenization solution. Under such conditions, these enzymes were stable over at least 4 or 1 weeks, respectively.

Animals↗

Glutathione, glutathione S-transferase and glutathione reductase in human erythrocytes and lymphocytes as a function of sex.

We review the role of glutathione (GSH) and its metabolizing enzymes, glutathione S-transferase (GST) and glutathione reductase (GSR) in drug metabolism and in the elimination of foreign compounds. Levels of GSH and the activity of these enzymes may be greatly influenced by drugs and other substances in the body. We therefore determined GSH levels and the activities of GST and GSR in human erythrocytes and lymphocytes in males and females in three age groups. There was no significant difference between males and females in the three age groups in respect of GSH levels and GST and GSR activities. GSH levels in erythrocytes were higher than those in lymphocytes when expressed per mg protein, but lower than those in lymphocytes when expressed per 10(6) cells. The activities of both GST and GSR were found to be higher in lymphocytes than in erythrocytes.

Adolescent↗

Glutathione, glutathione reductase and glutathione S-transferase activities in erythrocytes and lymphocytes in chronic renal disease.

Erythrocyte and lymphocyte reduced glutathione (GSH) levels, and glutathione reductase (GR) and glutathione S-transferase (GST) activities have been investigated in uremic patients pre- and post-dialysis and normal subjects of the same age span. GSH levels and GST activities in erythrocytes and lymphocytes and GR activity in lymphocytes from uremic patients were higher as compared to the corresponding controls. Dialysis resulted in a 17% decrease in GSH levels in erythrocytes. Hemodialysis did not significantly alter erythrocyte GST and GR activities. Hemodialysis produced a 50% decrease in lymphocyte GST activity and a 32% decrease in lymphocyte GR activity. Elevated levels of GSH and increased activities of GST and GR in blood cells of uremic patients may be associated with a compensatory protective mechanism against accumulating toxic wastes in uremic plasma.

Adult↗

Glutathione metabolism of the erythrocyte. The enzymic cleavage of glutathione-haemoglobin preparations by glutathione reductase.

A complex of haemoglobin and GSH was prepared by incubating haemoglobin with GSH and acetylphenylhydrazine. GSH could be released from the crude preparation by incubation with NADPH. However, when the haemoglobin preparation was separated from glutathione reductase by DEAE-Sephadex chromatography, NADPH no longer released GSH. Rather, the addition of a combination of either partially purified human erythrocyte or crystalline glutathione reductase and NADPH was required to release GSH from the haemoglobin-GSH complex. This complex is commonly believed to represent a mixed disulphide of GSH and the cysteine-beta-93 thiol group. This interpretation was supported by the finding that prior alkylation of available haemoglobin thiol groups prevented the formation of the complex. By using haemoglobin-[(35)S]GSH complex as a substrate, it was shown that GSH itself released the radioactivity from the complex only very slowly. In contrast, the release of [(35)S]GSH was very rapid in the presence of NADPH and glutathione reductase. This suggests that the cleavage of the haemoglobin-GSH complex is not mediated by GSH with cyclic reduction of GSSG formed, but rather proceeds enzymically through glutathione reductase.

Alkylation↗

Vitamin E, ascorbate, glutathione, glutathione disulfide, and enzymes of glutathione metabolism in cultures of chick astrocytes and neurons: evidence that astrocytes play an important role in antioxidative processes in the brain.

GSH, GSSG, vitamin E, and ascorbate were measured in 14-day cultures of chick astrocytes and neurons and compared with levels in the forebrains of chick embryos of comparable age. Activities of enzymes involved in GSH metabolism were also measured. These included gamma-glutamylcysteine synthetase, GSH synthetase, gamma-glutamyl cyclotransferase, gamma-glutamyltranspeptidase, glutathione transferase (GST), GSH peroxidase, and GSSG reductase. The concentration of lipid-soluble vitamin E in the cultured neurons was found to be comparable with that in the forebrain. On the other hand, the concentration of vitamin E in the astrocytes was significantly greater in the cultured astrocytes than in the neurons, suggesting that the astrocytes are able to accumulate exogenous vitamin E more extensively than neurons. The concentrations of major fatty acids were higher in the cell membranes of cultured neurons than those in the astrocytes. Ascorbate was not detected in cultured cells although the chick forebrains contained appreciable levels of this antioxidant. GSH, total glutathione (i.e., GSH and GSSG), and GST activity were much higher in cultured astrocytes than in neurons. gamma-Glutamylcysteine synthetase activity was higher in the cultured astrocytes than in the cultured neurons. GSH reductase and GSH peroxidase activities were roughly comparable in cultured astrocytes and neurons. The high levels of GSH and GST in cultured astrocytes appears to reflect the situation in vivo. The data suggest that astrocytes are resistant to reactive oxygen species (and potentially toxic xenobiotics) and may play a protective role in the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Picomole analysis of glutathione, glutathione disulfide, glutathione S-sulfonate, and cysteine S-sulfonate by high-performance liquid chromatography.

A method for simultaneous detection of picomole quantities of glutathione (GSH), glutathione disulfide (GSSG), glutathione S-sulfonate (GSSO3H), and cysteine S-sulfonate (CYSSO3H) by high-performance liquid chromatography has been developed. Compounds are separated by anion-exchange chromatography using a citric acid buffer system, and then derivatized postcolumn using o-phthalaldehyde with 2-mercaptoethanol, heated to 70 degrees C, and detected by fluorescence. The compounds elute with retention times of 12.5 min for GSH, 27.5 min for CYSSO3H, 29.8 min for GSSG, and 33.0 minutes for GSSO3H, with detection limits of 10, 200, 10, and 50 pmol, respectively. Recoveries are 103% for GSH, 102% for GSSG, 100% for CYSSO3H, and 96% for GSSO3H. Determination of target compounds in cells is described.

Animals↗

Purification and physical characterization of glutathione S-transferase K. Differential use of S-hexylglutathione and glutathione affinity matrices to isolate a novel glutathione S-transferase from rat liver.

A novel hepatic enzyme, glutathione S-transferase K, is described that, unlike previously characterized transferases, possesses little affinity for S-hexylglutathione-Sepharose 6B but can be isolated because it binds to a glutathione affinity matrix. A purification scheme for this new enzyme was devised, with the use of DEAE-cellulose, S-hexylglutathione-Sepharose 6B, glutathione-Sepharose 6B and hydroxyapatite chromatography. The final hydroxyapatite step results in the elution of three chromatographically interconvertible forms, K1, K2 and K3. The purified protein has an isoelectric point of 6.1 and comprises subunits that are designated Yk (Mr 25,000); during sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, it migrates marginally faster than the Ya subunit but slower than the pulmonary Yf monomer (Mr 24,500). Transferase K displays catalytic, immunochemical and physical properties that are distinct from those of other liver transferases. Tryptic peptide maps suggest that transferase K is a homodimer, or comprises closely homologous subunits. The tryptic fingerprints also demonstrate that, although transferase K is structurally separate from previously described hepatic forms, a limited sequence homology exists between the Yk, Ya and Yc polypeptides. These structural data are in accord with the immunochemical results presented in the accompanying paper [Hayes & Mantle (1986) Biochem. J. 233, 779-788].

Amino Acids↗

Glutathione oxidation by hypochlorous acid in endothelial cells produces glutathione sulfonamide as a major product but not glutathione disulfide.

Treatment of cells with hypochlorous acid (HOCl) at sublethal doses causes a concentration-dependent loss in reduced glutathione (GSH) levels. We have investigated the products of the reaction of HOCl with GSH in human umbilical vein endothelial cells. Despite a complete loss of GSH, there were only very small increases in intracellular and extracellular glutathione disulfide and glutathione sulfonic acid after exposure to HOCl. (35)S labeling of the GSH pool showed only a minimal increase in protein-bound GSH, suggesting that S-thiolation was not a major contributor to HOCl-mediated loss of GSH in endothelial cells. Rather, the products of the reaction were mostly exported from cells and included a peak that co-eluted with the cyclic sulfonamide that is a product of the reaction of GSH with reagent HOCl. Evidence of this species in endothelial cell supernatants after HOCl treatment was also obtained using electrospray mass spectrometry. In conclusion, exposure to HOCl causes the irreversible loss of cellular GSH with the formation of novel products that are rapidly exported from the cell, and resynthesis of GSH will be required to restore levels. The loss of GSH would alter the redox state of the cell and compromise its defenses against further oxidative stress.

Cells, Cultured↗

Normal bronchial epithelial cell expression of glutathione transferase P1, glutathione transferase M3, and glutathione peroxidase is low in subjects with bronchogenic carcinoma.

Normal bronchial epithelial cells (NBECs) are at risk for damage from inhaled and endogenous oxidative species and from epoxide metabolites of inhaled polycyclic aromatic hydrocarbons. Epidemiological and in vitro data suggest that interindividual variation in this risk may result from variation in NBEC expression of enzymes that inactivate reactive species by conjugating them to glutathione. Quantitative competitive reverse transcription-PCR was used to measure mRNA levels of glutathione transferases (GSTs) and glutathione peroxidases (GSHPxs) in primary NBECs from subjects with or without bronchogenic carcinoma. Mean expression levels (mRNA/10(3) beta-actin mRNA) in NBECs from 23 subjects without bronchogenic carcinoma compared to those from 11 subjects with bronchogenic carcinoma respectively (in parentheses) were: mGST (26.0, 6.11), GSTM3 (0.29, 0.09), combined GSTM1,2,4,5 (0.98, 0.60), GSTT1 (0.84, 0.76), GSTP1 (287, 110), GSHPx (140, 62.1), and GSHPxA (0.43, 0.34). Levels of GSTP1, GSTM3, and GSHPx were significantly (P < 0.05) lower in NBECs from subjects with bronchogenic carcinoma. Further, the gene expression index formed by multiplying the values for mGST x GSTM3 x GSHPx x GSHPxA x GSTP1 had a sensitivity (90%) and specificity (76%) for detecting NBECs from bronchogenic carcinoma subjects that was better than any individual gene. In cultured NBECs derived from eight individuals without bronchogenic carcinoma and incubated under identical conditions such that environmental effects were minimized, the mean level of expression and degree of interindividual variation for each gene evaluated was less than that observed in primary NBECs. Data from these studies support the hypotheses that (a) interindividual variation in risk for bronchogenic carcinoma results in part from interindividual variation in NBEC expression of antioxidant genes; (b) gene expression indices will better identify individuals at risk for bronchogenic carcinoma than individual gene expression values; and (c) both hereditary and environmental exposures contribute to the level of and interindividual variation in gene expression observed in primary NBECs. Many epidemiological studies have been designed to evaluate risk associated with polymorphisms or gene expression levels of putative susceptibility genes based on measurements in surrogate tissues, such as peripheral blood lymphocytes. Based on data presented here, it will be important to include the assessment of NBECs in future studies. Measurement of antioxidant gene expression in NBECs may identify the 5-10% of individuals at risk for bronchogenic carcinoma. Bronchoscopic sampling of NBECs from smokers and ex-smokers then will allow susceptible individuals to be entered into surveillance and/or chemoprevention studies.

Adolescent↗