γ-Glutamylcysteine synthetase: mRNA stabilization and independent subunit transcription by 4-hydroxy-2-nonenal

1998 ◽  
Vol 275 (5) ◽  
pp. L861-L869 ◽  
Author(s):  
Rui-Ming Liu ◽  
Lin Gao ◽  
Jinah Choi ◽  
Henry Jay Forman
Keyword(s):  
De Novo ◽  
Mrna Level ◽  
Protein Synthesis Inhibitor ◽  
Lipid Peroxidation Product ◽  
Synthesis Inhibitor ◽  
Mrna Stabilization ◽  
Subunit Mrna ◽  
Mrna Content ◽  
Glutamylcysteine Synthetase ◽  
The Stability

γ-Glutamylcysteine synthetase (GCS), the rate-limiting enzyme in de novo glutathione (GSH) synthesis, is composed of one catalytic (heavy) and one regulatory (light) subunit. Although both subunits are increased at the mRNA level by oxidants, it is not clear whether they are regulated through the same mechanism. 4-Hydroxy-2-nonenal (4HNE), a lipid peroxidation product, may act as a mediator for the induction of gene expression by oxidants. In the present study, 4HNE was used to study the mechanism of induction of the two GCS subunits in rat lung epithelial L2 cells. 4HNE increased both the transcription rates and the stability of mRNA for both GCS subunits, resulting in an increased mRNA content for both subunits. Both GCS subunit proteins and enzymatic activities also increased. Emetine, a protein synthesis inhibitor, blocked the increase in GCS light subunit mRNA but not the increase in GCS heavy subunit mRNA. This suggested that although 4HNE increased transcription and stabilization of both GCS subunit mRNAs, the signaling pathways involved in the induction of the two GCS subunits differed.

Mechanisms of regulation of G11α protein by dexamethasone in osteoblastic UMR 106–01 cells

2002 ◽  
Vol 282 (1) ◽  
pp. E24-E30 ◽  
Author(s):  
Ricky Cheung ◽  
Jane Mitchell
Keyword(s):  
De Novo ◽  
Mrna Level ◽  
Time Lag ◽  
Regulatory Protein ◽  
Protein Synthesis Inhibitor ◽  
Osteosarcoma Cell ◽  
Dependent Manner ◽  
Synthesis Inhibitor ◽  
Glucocorticoid Treatment ◽  
Umr 106

We have previously demonstrated that glucocorticoids increased Gq/11α protein expression and phospholipase C activity in the rat osteosarcoma cell line UMR 106–01. In this study, we demonstrated that G11α is the primary Gq-subtype family member expressed in UMR cells. Dexamethasone treatment increased the expression of G11α protein in both a time- and a dose-dependent manner. Glucocorticoid treatment significantly increased the half-life of G11α protein from 20.3 to 63 h. Steady-state G11α mRNA level was also increased by glucocorticoid treatment by ∼70%. This change was not the result of changes in RNA stability but rather the result of increased transcription, because the glucocorticoid-mediated upregulation of G11α mRNA was blocked by the transcription inhibitor actinomycin D. The dexamethasone induction of G11α mRNA occurred after a time lag of 12–24 h and was blocked by the protein synthesis inhibitor cycloheximide. These results suggest that the dexamethasone-induced rise in G11α protein results primarily from changes in the degradation rate of the protein, whereas changes in G11α mRNA play a smaller role and require de novo synthesis of regulatory protein(s).

Effects of nonsulfur and sulfur amino acids on the regulation of hepatic enzymes of cysteine metabolism

1999 ◽  
Vol 277 (1) ◽  
pp. E144-E153 ◽  
Author(s):  
Deborah L. Bella ◽  
Christine Hahn ◽  
Martha H. Stipanuk
Keyword(s):  
Amino Acids ◽  
Specific Activity ◽  
Mrna Level ◽  
Basal Diet ◽  
Cysteine Dioxygenase ◽  
Sulfur Amino Acids ◽  
Subunit Mrna ◽  
Cysteine Metabolism ◽  
Glutamylcysteine Synthetase

To determine the role of nonsulfur vs. sulfur amino acids in regulation of cysteine metabolism, rats were fed a basal diet or diets supplemented with a mixture of nonsulfur amino acids (AA), sulfur amino acids (SAA), or both for 3 wk. Hepatic cysteine-sulfinate decarboxylase (CSDC), cysteine dioxygenase (CDO), and γ-glutamylcysteine synthetase (GCS) activity, concentration, and mRNA abundance were measured. Supplementation with AA alone had no effect on any of these measures. Supplementation of the basal diet with SAA, with or without AA, resulted in a higher CDO concentration (32–45 times basal), a lower CSDC mRNA level (49–64% of basal), and a lower GCS-heavy subunit mRNA level (70–76%). The presence of excess SAA and AA together resulted in an additional type of regulation: a lower specific activity of all three enzymes was observed in rats fed diets with an excess of AA and SAA. Both SAA and AA played a role in regulation of these three enzymes of cysteine metabolism, but SAA had the dominant effects, and effects of AA were not observed in the absence of SAA.

scholarly journals Quinones increase γ-glutamyl transpeptidase expression by multiple mechanisms in rat lung epithelial cells

1998 ◽  
Vol 274 (3) ◽  
pp. L330-L336 ◽  
Author(s):  
Rui-Ming Liu ◽  
Michael Ming Shi ◽  
Cecilia Giulivi ◽  
Henry Jay Forman
Keyword(s):  
Specific Activity ◽  
Lung Epithelial Cells ◽  
Secondary Response ◽  
Protein Synthesis Inhibitor ◽  
Rat Lung ◽  
Synthesis Inhibitor ◽  
Lung Epithelial ◽  
Mrna Content ◽  
Gsh Metabolism ◽  
Glutamyl Transpeptidase

γ-Glutamyl transpeptidase (GGT) plays an important role in glutathione (GSH) metabolism. GGT expression is increased in oxidant-challenged cells; however, the signaling mechanisms involved are uncertain. The present study used 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), a redox cycling quinone that continuously produced H2O2in rat lung epithelial L2 cells. It was found that DMNQ increased GGT mRNA content by increasing transcription, as measured by nuclear run-on. This was accompanied by increased GGT specific activity. Cycloheximide, a protein synthesis inhibitor, blocked neither the increased GGT mRNA content nor the increased GGT transcription rate caused by DMNQ, suggesting that increased GGT transcription was a direct rather than secondary response. Previous data from this laboratory (R.-M. Liu, H. Hu, T. W. Robison, and H. J. Forman. Am. J. Respir. Cell Mol. Biol.14: 186–191, 1996) showed that tert-butylhydroquinone (TBHQ) increased GGT mRNA content by increasing its stability. TBHQ differs markedly from DMNQ in terms of its conjugation with GSH and H2O2generation. Together, the data suggest that quinones upregulate GGT through multiple mechanisms, increased transcription and posttranscriptional modulation, which are apparently mediated through generation of reactive oxygen species and GSH conjugate formation, respectively.

Determinants of kinin release in isolated rat hindquarters

1998 ◽  
Vol 274 (1) ◽  
pp. R120-R125 ◽  
Author(s):  
Tohru Sakakibara ◽  
Thomas H. Hintze ◽  
Alberto Nasjletti
Keyword(s):  
Protein Synthesis ◽  
Trypsin Inhibitor ◽  
De Novo ◽  
Soybean Trypsin Inhibitor ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Bicarbonate Buffer ◽  
Kallikrein Inhibitor ◽  
Isolated Rat

We studied the determinants of kinin release into the venous effluent of rat hindquarters perfused with Krebs bicarbonate buffer. Kinin release in preparations perfused with control media (14.6 ± 2.5–20.7 ± 6.7 pg/15 min) was surpassed by that in preparations perfused with media containing kininase inhibitors (243 ± 53 to 276 ± 78 pg/15 min). Kinin release increased when purified kininogen (from 242 ± 43 to 3,365 ± 725 pg/15 min) or kallikrein (from 270 ± 49 to 30,649 ± 8,040 pg/15 min) was added to the perfusate. Conversely, kinin release fell when the kallikrein inhibitor aprotinin (from 272 ± 58 to 122 ± 27 pg/15 min) or soybean trypsin inhibitor (from 273 ± 52 to 195 ± 25 pg/15 min) was added. Both basal and kininogen-induced kinin release were attenuated in preparations perfused with media containing cycloheximide, a protein synthesis inhibitor, but kallikrein-induced kinin release was not. These data suggest that kinin release from perfused rat hindquarters reflects the activity of both the kinin-degrading and kinin-generating pathways and that the latter is sustained by a kallikrein manufactured de novo and by preexistent kininogen(s).

scholarly journals Natural and environmental oestrogens induce TGFB1 synthesis in oviduct cells

Reproduction ◽  
2018 ◽  
Vol 155 (3) ◽  
pp. 233-244 ◽  
Author(s):  
Barbara P S Cometti ◽  
Raghvendra K Dubey ◽  
Bruno Imthurn ◽  
Marinella Rosselli
Keyword(s):  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
De Novo ◽  
Embryo Implantation ◽  
Early Embryo ◽  
Biochanin A ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Paracrine Factors ◽  
Aryl Hydrocarbon

Autocrine/paracrine factors generated in response to 17β-oestradiol (E2), within the oviduct, facilitate early embryo development for implantation. Since transforming growth factor beta 1 (TGFB1) plays a key role in embryo implantation, regulation of its synthesis by E2 may be of biological/pathophysiological relevance. Here, we investigated whether oviduct cells synthesize TGFB1 and whether E2 and environmental oestrogens (EOEs; xenoestrogens and phytoestrogens) modulate its synthesis. Under basal conditions, bovine oviduct cells (OCs; oviduct epithelial cells and oviduct fibroblasts; 1:1 ratio) synthesized TGFB1. E2 concentration-dependent induced TGFB1 levels in OCs and these effects were mimicked by some, but not all EOEs (genistein, biochanin A and 4-hydroxy-2′,4′,6′-trichlorobiphenyl, 4-hydroxy-2′,4′,6′-dichlorobiphenyl); moreover, EOEs enhanced (P < 0.05) the stimulatory effects of E2 on TGFB1 synthesis. The OCs expressed oestrogen receptors alpha and beta and aryl hydrocarbon; moreover, co-treatment with ER antagonist ICI182780 blocked the stimulatory effects of E2 and EOEs on TGFB1 synthesis. Treatment with non-permeable E2-BSA failed to induce TGFB1, thereby ruling out the involvement of membrane ERs. Cycloheximide (protein synthesis inhibitor) blocked E2-induced TGFB1 synthesis providing evidence forde novosynthesis. The stimulatory effects of E2 and EOEs, were inhibited (P < 0.05) by MAPK inhibitor (PD98059), whereas intracellular-Ca2+chelator (BAPTA-AM) and adenylyl cyclase inhibitor (SQ22536) abrogated the effects of E2, but not EOEs, suggesting that post-ER effects of E2 and EOEs involve different pathways. Our results provide the first evidence that in OCs, E2 and EOEs stimulate TGFB1 synthesis via an ER-dependent pathway. Exposure of the oviduct to EOEs may result in continuous/sustained induction of TGFB1 levels in a non-cyclic fashion and may induce deleterious effects on reproduction.

scholarly journals Social Fear Memory Requires Two Stages of Protein Synthesis in Mice

2020 ◽  
Vol 21 (15) ◽  
pp. 5537
Author(s):  
Johannes Kornhuber ◽  
Iulia Zoicas
Keyword(s):  
Protein Synthesis ◽  
Temporal Dynamics ◽  
De Novo ◽  
Fear Memory ◽  
Protein Synthesis Inhibitor ◽  
Dependent Manner ◽  
Synthesis Inhibitor ◽  
Systemic Injection ◽  
Social Fear ◽  
Two Stages

It is well known that long-term consolidation of newly acquired information, including information related to social fear, require de novo protein synthesis. However, the temporal dynamics of protein synthesis during the consolidation of social fear memories is unclear. To address this question, mice received a single systemic injection with the protein synthesis inhibitor, anisomycin, at different time-points before or after social fear conditioning (SFC), and memory was assessed 24 h later. We showed that anisomycin impaired the consolidation of social fear memories in a time-point-dependent manner. Mice that received anisomycin 20 min before, immediately after, 6 h, or 8 h after SFC showed reduced expression of social fear, indicating impaired social fear memory, whereas anisomycin caused no effects when administered 4 h after SFC. These results suggest that consolidation of social fear memories requires two stages of protein synthesis: (1) an initial stage starting during or immediately after SFC, and (2) a second stage starting around 6 h after SFC and lasting for at least 5 h.

scholarly journals Differential regulation of γ-glutamylcysteine synthetase heavy and light subunit gene expression

1997 ◽  
Vol 326 (1) ◽  
pp. 167-172 ◽  
Author(s):  
Jiaxin CAI ◽  
Zong-Zhi HUANG ◽  
Shelly C. LU
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Steady State ◽  
Mrna Level ◽  
Rat Hepatocytes ◽  
Mrna Levels ◽  
Subunit Gene ◽  
Subunit Mrna ◽  
Glutamylcysteine Synthetase ◽  
Steady State Mrna Level

γ-Glutamylcysteine synthetase (GCS) is the rate-limiting enzyme in the biosynthesis of glutathione and is composed of a heavy and a light subunit. Although the heavy subunit is enzymically active alone, the light subunit plays an important regulatory role by making the holoenzyme function more efficiently. In the current study we examined whether conditions which are known to influence gene expression of the heavy subunit also influence that of the light subunit, and the mechanisms involved. Treatment of cultured rat hepatocytes with hormones such as insulin and hydrocortisone, or plating hepatocytes under low cell density increased the steady-state mRNA level of the heavy subunit only. Treatment with diethyl maleate (DEM), buthionine sulphoximine (BSO) and t-butylhydroquinone (TBH) increased the steady state mRNA level and gene transcription rates of both subunits. These treatments share in common their ability to induce oxidative stress and activate nuclear factor κB (NF-κB). Treatment with protease inhibitors 7-amino-1-chloro-3-tosylamido-2-heptanone (TLCK) or L-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK) had no influence on the basal NF-κB and GCS subunit mRNA levels, but blocked the activation of NF-κB by DEM, BSO and TBH, and the increase in GCS heavy subunit mRNA level by BSO and TBH. On the other hand, the DEM-, BSO- and TBH-induced increase in GCS light-subunit mRNA level was unaffected by TLCK and TPCK. Thus only the heavy subunit is hormonally regulated and growth sensitive, whereas both subunits are regulated by oxidative stress. Signalling through NF-κB is involved only in the oxidative-stress-mediated changes in the heavy subunit gene expression.

scholarly journals Signal transduction for chemotaxis and haptotaxis by matrix molecules in tumor cells.

1990 ◽  
Vol 110 (4) ◽  
pp. 1427-1438 ◽  
Author(s):  
S Aznavoorian ◽  
M L Stracke ◽  
H Krutzsch ◽  
E Schiffmann ◽  
L A Liotta
Keyword(s):  
Protein Synthesis ◽  
Matrix Protein ◽  
Type Iv Collagen ◽  
De Novo ◽  
Protein Synthesis Inhibitor ◽  
Dependent Manner ◽  
Recognition Sequence ◽  
Synthesis Inhibitor ◽  
Concentration Dependent Manner ◽  
Type Iv

Transduction of signals initiating motility by extracellular matrix (ECM) molecules differed depending on the type of matrix molecule and whether the ligand was in solution or bound to a substratum. Laminin, fibronectin, and type IV collagen stimulated both chemotaxis and haptotaxis of the A2058 human melanoma cell line. Peak chemotactic responses were reached at 50-200 nM for laminin, 50-100 nM for fibronectin, and 200-370 nM for type IV collagen. Checkerboard analysis of each attractant in solution demonstrated a predominantly directional (chemotactic) response, with a minor chemokinetic component. The cells also migrated in a concentration-dependent manner to insoluble step gradients of substratum-bound attractant (haptotaxis). The haptotactic responses reached maximal levels at coating concentrations of 20 nM for laminin and type IV collagen, and from 30 to 45 nM for fibronectin. Pretreatment of cells with the protein synthesis inhibitor, cycloheximide (5 micrograms/ml), resulted in a 5-30% inhibition of both chemotactic and haptotactic responses to each matrix protein, indicating that de novo protein synthesis was not required for a significant motility response. Pretreatment of cells with 50-500 micrograms/ml of synthetic peptides containing the fibronectin cell-recognition sequence GRGDS resulted in a concentration-dependent inhibition of fibronectin-mediated chemotaxis and haptotaxis (70-80% inhibition compared to control motility); negative control peptide GRGES had only a minimal effect. Neither GRGDS nor GRGES significantly inhibited motility to laminin or type IV collagen. Therefore, these results support a role for the RGD-directed integrin receptor in both types of motility response to fibronectin. After pretreatment with pertussis toxin (PT), chemotactic responses to laminin, fibronectin, and type IV collagen were distinctly different. Chemotaxis to laminin was intermediate in sensitivity; chemotaxis to fibronectin was completely insensitive; and chemotaxis to type IV collagen was profoundly inhibited by PT. In marked contrast to the inhibition of chemotaxis, the hepatotactic responses to all three ligands were unaffected by any of the tested concentrations of PT. High concentrations of cholera toxin (CT; 10 micrograms/ml) or the cAMP analogue, 8-Br-cAMP (0.5 mM), did not significantly affect chemotactic or haptotactic motility to any of the attractant proteins, ruling out the involvement of cAMP in the biochemical pathway initiating motility in these cells. The sensitivity of chemotaxis induced by laminin and type IV collagen, but not fibronectin, to PT indicates the involvement of a PT-sensitive G protein in transduction of the signals initiating motility to soluble laminin and type IV collagen.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of Cerophyl growth medium on exocytosis in Tetrahymena thermophila

1985 ◽  
Vol 78 (1) ◽  
pp. 23-48
Author(s):  
D.M. Pesciotta ◽  
B.H. Satir
Keyword(s):  
Cell Division ◽  
De Novo ◽  
Tetrahymena Thermophila ◽  
Freeze Fracture ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Particle Array ◽  
Proteose Peptone ◽  
Section Electron ◽  
Cell Changes

Culturing the ciliate Tetrahymena thermophila in Cerophyl has provided an opportunity for studying the assembly and/or synthesis of the intramembrane particle array, the rosette, which marks the site of exocytosis in these cells. Cultures grown in this medium cease cell division after only 12h and enter ‘stationary phase’ earlier (12h of growth) relative to growth in standard medium (proteose peptone). In addition, the cell changes from the normally observed pear-shaped body to a thinner more ellipsoid form. Despite the initial similarities to starving cells, several differences are observed in the Cerophyl-grown cells. One is that cell size remains constant for at least 72h in contrast to starved cells. Secondly, in spite of this block in cell division, results from freeze-fracture replicas of the cell membrane of these cells show that they continue to assemble rosettes, the number of which increases approximately six times, from 0.34 rosette/microgram2 to 2.1 rosettes/microgram2. Addition of the protein synthesis inhibitor, cycloheximide (6h exposure), during growth in Cerophyl shows that 70% of rosettes can be assembled, despite the blockage of translation, by using pre-existing component(s) from a pool. The remaining 30% must involve de novo synthesis of one or more components; this percentage can be increased with longer exposure to the drug. Thirdly, an apparent increase in the number of mucocysts is observed by thin-section electron microscopy. At first (12–24h) only docked mucocysts seem to accumulate in the cell. However, by 36h a considerable increase seems to have taken place, particularly in the number of mucocysts located in the cytoplasm. In the cycloheximide-treated cells this increase in mucocysts begins to be blocked after 6h of exposure to the drug. These observations are in agreement with the results obtained from the freeze-fracture data on the concomitant increase in number of rosettes. This system therefore offers the first possibility of exploring the biosynthesis of these components.

gamma-Glutamylcysteine synthetase and GSH increase in quinone-induced oxidative stress in BPAEC

1994 ◽  
Vol 267 (4) ◽  
pp. L414-L421 ◽  
Author(s):  
M. M. Shi ◽  
T. Iwamoto ◽  
H. J. Forman
Keyword(s):  
Oxidative Stress ◽  
Adaptive Response ◽  
Actinomycin D ◽  
De Novo ◽  
Reduced Form ◽  
Continuous Exposure ◽  
Total Glutathione ◽  
Mrna Content ◽  
Glutamylcysteine Synthetase ◽  
Rate Limiting

Glutathione (GSH), an important physiological antioxidant, is synthesized de novo by the sequential reactions of gamma-glutamylcysteine synthetase (gamma GCS) and GSH synthetase. In the present studies, incubation with the quinones 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) and menadione (MQ), which generate superoxide and hydrogen peroxide, was used to investigate GSH synthesis in bovine pulmonary artery endothelial cells under oxidative stress. MQ can also cause initial depletion of GSH through conjugation, whereas DMNQ cannot. during continuous exposure to DMNQ (5 or 10 microM), elevation of GSH by DMNQ started after 6 h, almost doubled after 24 h, and remained at this level to 48 h. The elevation of GSH by DMNQ was mostly in the reduced form, and the ratio of reduced to oxidized glutathione remained unchanged for the first 24 h. Treatment with MQ (25 or 50 microM) for 30 min caused a significant decrease in GSH and total glutathione. After changing the medium to remove any residual MQ, GSH content doubled during the next 12 h. The enzymatic activity of gamma GCS, the rate-limiting enzyme of GSH biosynthesis, increased twofold after 12 h of exposure of cells to either 5 microM DMNQ or 50 microM MQ. Both DMNQ and MQ treatment caused concentration- and time-dependent increases in gamma GCS-mRNA expression. The elevation of gamma GCS-mRNA content by DMNQ for 12 h was completely blocked by coincubation with 0.05 microgram/ml actinomycin D but not 0.5 microgram/ml cycloheximide, suggesting the elevation of gamma GCS-mRNA content occurred through increased transcription. Our results suggest that increased de novo GSH synthesis, mediated by an elevation in gamma GCS, constitutes an adaptive response to oxidative stress.

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