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Takahashi M, Yamaguchi H, Nakanishi H, Shioiri T, Nishizawa NK, Mori S. Cloning two genes for nicotianamine aminotransferase, a critical enzyme in iron acquisition (Strategy II) in graminaceous plants. PLANT PHYSIOLOGY 1999; 121:947-56. [PMID: 10557244 PMCID: PMC59459 DOI: 10.1104/pp.121.3.947] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/1999] [Accepted: 07/22/1999] [Indexed: 05/18/2023]
Abstract
Nicotianamine aminotransferase (NAAT), the key enzyme involved in the biosynthesis of mugineic acid family phytosiderophores (MAs), catalyzes the amino transfer of nicotianamine (NA). MAs are found only in graminaceous plants, although NA has been detected in every plant so far investigated. Therefore, this amino transfer reaction is the first step in the unique biosynthesis of MAs that has evolved in graminaceous plants. NAAT activity is dramatically induced by Fe deficiency and suppressed by Fe resupply. Based on the protein sequence of NAAT purified from Fe-deficient barley (Hordeum vulgare) roots, two distinct cDNA clones encoding NAAT, naat-A and naat-B, were identified. Their deduced amino acid sequences were homologous to several aminotransferases, and shared consensus sequences for the pyridoxal phosphate-binding site lysine residue and its surrounding residues. The expression of both naat-A and naat-B is increased in Fe-deficient barley roots, while naat-B has a low level of constitutive expression in Fe-sufficient barley roots. No detectable mRNA from either naat-A or naat-B was present in the leaves of either Fe-deficient or Fe-sufficient barley. One genomic clone with a tandem array of naat-B and naat-A in this order was identified. naat-B and naat-A each have six introns at the same locations. The isolation of NAAT genes will pave the way to understanding the mechanism of the response to Fe in graminaceous plants, and may lead to the development of cultivars tolerant to Fe deficiency that can grow in calcareous soils.
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Affiliation(s)
- M Takahashi
- Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, 332-0012 Saitama, Japan
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2
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Christoffels VM, Grange T, Kaestner KH, Cole TJ, Darlington GJ, Croniger CM, Lamers WH. Glucocorticoid receptor, C/EBP, HNF3, and protein kinase A coordinately activate the glucocorticoid response unit of the carbamoylphosphate synthetase I gene. Mol Cell Biol 1998; 18:6305-15. [PMID: 9774647 PMCID: PMC109217 DOI: 10.1128/mcb.18.11.6305] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A single far-upstream enhancer is sufficient to confer hepatocyte-specific, glucocorticoid- and cyclic AMP-inducible periportal expression to the carbamoylphosphate synthetase I (CPS) gene. To identify the mechanism of hormone-dependent activation, the composition and function of the enhancer have been analyzed. DNase I protection and gel mobility shift assays revealed the presence of a cyclic AMP response element, a glucocorticoid response element (GRE), and several sites for the liver-enriched transcription factor families HNF3 and C/EBP. The in vivo relevance of the transcription factors interacting with the enhancer in the regulation of CPS expression in the liver was assessed by the analysis of knockout mice. A strong reduction of CPS mRNA levels was observed in glucocorticoid receptor- and C/EBPalpha-deficient mice, whereas the CPS mRNA was normally expressed in C/EBPbeta knockout mice and in HNF3alpha and -gamma double-knockout mice. (The role of HNFbeta could not be assessed, because the corresponding knockout mice die at embryonic day 10). In hepatoma cells, most of the activity of the enhancer is contained within a 103-bp fragment, which depends for its activity on the simultaneous occupation of the GRE, HNF3, and C/EBP sites, thus meeting the requirement of a glucocorticoid response unit. In fibroblast-like CHO cells, on the other hand, the GRE in the CPS enhancer does not cooperate with the C/EBP and HNF3 elements in transactivation of the CPS promoter. In both hepatoma and CHO cells, stimulation of expression by cyclic AMP depends mainly on the integrity of the glucocorticoid pathway, demonstrating cross talk between this pathway and the cyclic AMP (protein kinase A) pathway.
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Affiliation(s)
- V M Christoffels
- Department of Anatomy and Embryology, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
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3
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Heiman AS, Ko DH, Chen M, Lee HJ. New steroidal anti-inflammatory antedrugs: methyl 3,20-dioxo-9 alpha-fluoro-11 beta,17 alpha,21-trihydroxy-1,4-pregnadiene-16 alpha-carboxylate and methyl 21-acetyloxy-3,20-dioxo-11 beta, 17 alpha-dihydroxy-9 alpha-fluoro-1,4-pregnadiene-16 alpha-carboxylate. Steroids 1997; 62:491-9. [PMID: 9185298 DOI: 10.1016/s0039-128x(97)00020-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Focused efforts have been made to increase local-to-systemic activity ratios of potent anti-inflammatory steroids for local and/or topical applications. The approach taken in the present investigation is based upon the concept of "antedrug," defined as a locally active compound that exerts its action at the application site but rapidly undergoes a predictable biotransformation to an inactive metabolite that is readily excreted upon entry into the systemic circulation. In continuing efforts to synthesize potent, anti-inflammatory steroids without systemic glucocorticoid activities, 9 alpha-fluoro-methyl 11 beta, 17 alpha, 21-trihydroxy-3,20-dioxo-pregna-1,4-diene-16 alpha-carboxylate (FP16CM) and its 21-acetate derivative (FP16CMAc) have been synthesized and screened. Novel antedrugs were evaluated for antiinflammatory activity in the acute croton oil-induced ear edema bioassay, adverse systemic effects in the 5-day croton oil model, receptor binding, and concomitant L-tyrosine-2-oxoglutarate aminotransferase (EC 2.6.1.5) (TAT) enzyme induction in HTC cells in culture. Following a single topical application in the croton oil-induced ear edema bioassay, treatment with all compounds resulted in dose-dependent inhibition of edema. From these dose-response profiles, the following ID50 values (nmol resulting in a 50% reduction of edema) were calculated: 817, 540, 266, and 67 for hydrocortisone (HC), prednisolone (P), FP16CM, and FP16CMAc, respectively. Calculated relative potencies, setting HC = 1.0, were P, 1.5; FP16CM, 3.1, and FP16CMAc, 12.2. Results of the 5-day rat croton oil ear edema bioassay indicated that, in contrast to the parent compound P, the novel steroidal antedrugs did not significantly alter body weight gain, thymus weights, or plasma corticosterone levels. Relative binding potencies for cytosolic HTC glucocorticoid receptors were 1.0, 20.1, 5.4, and 2.5 for HC, P, FP16CM, and FP16CMAc, respectively. As predicted by the antedrug concept, FP16CM and FP16CMAc were very weak agonists for induction of TAT in HTC cells. Collectively, results of these investigations suggest that modification of P, which included addition of the 9-fluoro and 16-methoxycarbonyl group alone or in conjunction with a 21-acetoxy moiety, increase topical anti-inflammatory activity without significant adverse systemic effects. These new antedrugs may be useful as anti-inflammatory steroids for local applications.
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Affiliation(s)
- A S Heiman
- Center for Anti-Inflammatory Research, Florida A & M University, College of Pharmacy and Pharmaceutical Sciences, Tallahassee 32307, USA
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Galigniana MD, Vicent GP, Burton G, Lantos CP. Features of the shuttle pair 11 beta-hydroxyprogesterone-11-ketoprogesterone. Steroids 1997; 62:358-64. [PMID: 9090796 DOI: 10.1016/s0039-128x(96)00244-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
11 beta-hydroxyprogesterone (HOP) and 11-ketoprogesterone (KP) are reversible components of a shuttle pair whose interconversion in rat liver is catalyzed by isoform-1 of 11 beta-hydroxysteroid dehydrogenase. Kidneys also produce this interconversion. The present study was carried out to investigate the shuttle pair and its components in the rat. As in corticosterone/11-dehydrocorticosterone, oxidation is more effective at an alkaline pH, while reduction prevails at a neutral pH. Moreover, both reactions are inhibited by the detergent 3-[(3-cholamido propyl)-dimethylammonio]-1-propane-sulphonate (CHAPS). However, at variance with the 11-ketosteroids cortisone (E) and 11-dehydrocorticosterone (A) thought to be "inactive," KP has slight direct Na(+)-retaining properties, and it, as well as HOP, induces glucocorticoids (11 beta-hydroxycorticoids) to retain sodium. 11-ketoprogesterone exhibits 17 times better affinity for native type 1 mineralocorticoid receptor than HOP and a 3-fold affinity for partially purified (transcortin free) mineralocorticoid receptor. However, KP, in contrast to HOP, binds only weakly to transcortin, not at all to glucocorticoid receptor, and requires reduction at C11 for tyrosine aminotransferase (TAT) induction.
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Affiliation(s)
- M D Galigniana
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
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Heiman AS, Tonner LE. The acute effect of lead acetate on glucocorticoid regulation of tyrosine aminotransferase in hepatoma cells. Toxicology 1995; 100:57-68. [PMID: 7624883 DOI: 10.1016/0300-483x(95)03061-j] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Specific cellular sites of action of the environmental pollutant, lead, have not been completely defined. The present investigations were conducted to test the hypothesis that lead exposure perturbs glucocorticoid-mediated effects in hormonal target tissues. The cell culture model chosen for these investigations was the effects of lead on glucocorticoid-regulated tyrosine aminotransferase (TAT) specific activity in the H4-II-C3 hepatoma cells. Cells were treated with 300 nM-10 microM lead acetate for 24 or 48 h in absence or presence of the inducing agent, dexamethasone. Lead dose-dependently inhibited TAT specific activity up to 52% and 61% following 24 and 48 h lead treatments, respectively. These treatment times and concentrations of lead acetate did not significantly alter total cell numbers, [3H]thymidine incorporation or trypan blue exclusion. Glucocorticoid receptor-binding studies yielded a Kd = 8.3 nM and a Bmax = 290 fmol/mg protein in untreated cells versus a Kd = 9.2 nM and Bmax = 262 fmol/mg protein in cells exposed to 10 microM lead acetate for 48 h. Treatment with lead did not significantly perturb uptake of the inducing glucocorticoids or initial cytosolic receptor-binding events. To sustain induced levels of TAT, glucocorticoid must be continuously present. Following steroid withdrawal, enzyme de-induction was significantly altered in lead-treated cells. At 6 h following dexamethasone withdrawal, TAT levels had decreased to 51% of maximum in sodium acetate-treated cells. This was significantly reduced to 33% of maximum in lead acetate-treated cells. Lead treatment of HTC cells was also shown to ameliorate PMA amplification of dexamethasone-induced TAT activity. Taken together, these results suggest that acute exposure of cells to lead may inhibit processes involved in glucocorticoid-mediated enzyme induction within the hormonal target cell. Results suggest that lead may be acting to increase the turnover of TAT by actions at the transcription, translation and/or posttranslational level. Lead may also be affecting PKC-mediated phosphorylations in the glucocorticoid-TAT signal transduction system.
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Affiliation(s)
- A S Heiman
- College of Pharmacy and Pharmaceutical Sciences, Florida A & M University, Tallahassee 32307, USA
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Coleman WB, Smith GJ, Grisham JW. Development of dexamethasone-inducible tyrosine aminotransferase activity in WB-F344 rat liver epithelial stemlike cells cultured in the presence of sodium butyrate. J Cell Physiol 1994; 161:463-9. [PMID: 7962128 DOI: 10.1002/jcp.1041610309] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Sodium butyrate acts as a differentiation-promoting agent for a wide variety of cell types, including some tumor cell lines. In this study, we examined the effects of sodium butyrate (SB) on the functional differentiation of cultured WB-F344 rat liver epithelial stemlike cells. Treatment of WB-F344 cells with 3.75 mM SB resulted in an inhibition of cellular proliferation, alterations to normal cellular morphology (increased cell size and decreased nuclear/cytoplasmic ratio), and significant increases in cellular protein synthesis. The SB-mediated changes in cell morphology, proliferative status, and protein catabolism were accompanied by development of dexamethasone-inducible tyrosine aminotransferase (TAT) enzyme activity. Culture of WB-F344 cells in growth medium containing SB and dexamethasone (DEX; 1 x 10(-6) M) resulted in greater than sevenfold increase in the basal TAT activity compared with control cultures. An additional sixfold increase in TAT activity was observed when cells cultured in medium containing SB and DEX were exposed to 1 x 10(-7) M DEX during the last 24 hours of culture. The DEX-inducible TAT activity developed by SB-treated WB-F344 cells responded to the modulating effects of insulin and L-tyrosine in a manner that closely resembled that reported for cultured hepatocytes and hepatoma cell lines. These studies show that treatment of WB-F344 rat liver epithelial stemlike cells with the differentiation-promoting agent SB in vitro leads to expression of the differentiation-specific hepatocyte enzyme TAT.
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Affiliation(s)
- W B Coleman
- Department of Pathology, School of Medicine, University of North Carolina, Chapel Hill 27599
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Yoshino M, Mori S, Nakatsuka M, Shibata Y. Acclimatization to hypoxia modulates the tryptophan 2,3-dioxygenase activity in rats exposed to simulated high altitude. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1991; 99:571-3. [PMID: 1769205 DOI: 10.1016/0305-0491(91)90339-f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. Exposure of rats to an 8000 m altitude increased the hepatic tryptophan 2,3-dioxygenase (EC 1.13.1.12) activity. 2. Acclimatization to hypoxia by a repeated exposure to an altitude of 5000 m induced a marked decrease in liver tryptophan dioxygenase activity after the rats were subjected to an 8000 m altitude, but a pre-exposure to 4000 m altitude showed no effect on the enzyme activity. 3. Plasma tryptophan was rapidly decreased by exposure to 8000 m altitude to the same extent in the acclimatized and non-acclimatized rats. 4. Plasma tryptophan may be utilized as the substrate for tryptophan dioxygenase in liver of the non-acclimatized rats under highly hypoxic conditions; however, acclimatized rats can reserve tryptophan as the substrate for the alternative metabolism other than the degradation pathway in liver.
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Affiliation(s)
- M Yoshino
- Department of Genetics, Institute for Developmental Research, Aichi Prefectural Colony, Japan
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8
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Meyer R, McMorris FA. The synergistic interaction of hydrocortisone and dibutyryl cyclic AMP during enzyme induction in hybrids between rat C6 glioma cells and FU5AH hepatoma cells. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 886:143-51. [PMID: 2869787 DOI: 10.1016/0167-4889(86)90220-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The hormone-responsive enzymes tyrosine aminotransferase and glycerol-3-phosphate dehydrogenase were studied with respect to current models of the mechanism of glucocorticoid/cAMP interaction during the induction of enzyme activity in responsive cell hybrids between rat C6 glioma cells and rat FU5AH hepatoma cells. The results of experiments involving protein and mRNA synthesis inhibitors, sequential addition of inducers, and the assay of cyclic-AMP-dependent protein kinase could not be adequately explained by any one model of inducer interaction. Comparison of the hybrid clones revealed the presence of factors that may modify induction but that are not essential for synergistic induction.
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9
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Sistare FD, Haynes RC. Acute stimulation by glucocorticoids of gluconeogenesis from lactate/pyruvate in isolated hepatocytes from normal and adrenalectomized rats. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)38941-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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10
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Rohner-Jeanrenaud F, Jeanrenaud B. Oversecretion of glucagon by pancreases of ventromedial hypothalamic-lesioned rats: a re-evaluation of a controversial topic. Diabetologia 1984; 27:535-9. [PMID: 6510598 DOI: 10.1007/bf00290391] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Glucagon secretion by perfused pancreases of control and ventromedial hypothalamic-lesioned rats was studied in response to a mixture of 20 different amino-acids used at physiological or pharmacological concentrations, and under experimental conditions near to or different from physiological situations. When experimental conditions are too extreme (lack of glucose with 5 or 15 mmol/l final amino-acid concentration), there was no difference of glucagon secretion between pancreases of control and ventromedial hypothalamic-lesioned animals. However, when experimental conditions are as close as possible to those prevailing in vivo (presence of 5 mmol/l glucose with 2.5 or 5 mmol/l amino-acid concentration), pancreases from ventromedial hypothalamic-lesioned rats clearly oversecrete glucagon when compared with control rats (with 2.5 mmol/l amino-acid: controls: 7.9, ventromedialhypothalamic-lesioned: 17.1 ng/20 min, p less than 0.05; with 5 mmol/l amino-acid: controls: 12.6, ventromedialhypothalamic-lesioned: 31.0 ng/20 min, p less than 0.025). Upon extrapolating these results to a situation in vivo, this study indicates that ventromedial hypothalamic-lesioned rats secrete more glucagon than controls in response to physiological stimuli, at least at the level of the portal vein. This could explain why the lesioned rats, known to be hyperinsulinaemic, are nevertheless normoglycaemic and have increased plasma urea levels.
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11
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Induction of cytochrome P-450 by glucocorticoids in rat liver. II. Evidence that glucocorticoids regulate induction of cytochrome P-450 by a nonclassical receptor mechanism. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43508-3] [Citation(s) in RCA: 132] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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12
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Groenewald JV, Terblanche SE, Oelofsen W. Tyrosine aminotransferase: characteristics and properties. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1984; 16:1-18. [PMID: 6141963 DOI: 10.1016/0020-711x(84)90045-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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13
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Strinden ST, Stellwagen RH. Possible involvement of cGMP in the control of tyrosine aminotransferase degradation in rat hepatocytes. J Cell Physiol 1983; 117:69-75. [PMID: 6137488 DOI: 10.1002/jcp.1041170111] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Addition of theophylline to primary cultures of rat hepatocytes in which tyrosine aminotransferase had been preinduced with dexamethasone caused a further increase in specific activity of the enzyme. This increase was due in part to a reduction in the rate of tyrosine aminotransferase degradation that began about 2 hr after theophylline was added. The level of cGMP also increased with a similar time lag following the addition of theophylline. The concentration of theophylline which produced the above effects (1 mM) did not alter the rate of general protein degradation in hepatocytes. Addition of 8-bromo-cGMP (0.5 mM) resulted in an immediate reduction in the rate of tyrosine aminotransferase degradation and in an increase in the activity of the enzyme. Treating hepatocytes with MnCl2 (0.9 mM) caused an elevation of cGMP and a concomitant slowing of tyrosine aminotransferase degradation without changing the level of cAMP significantly. These results suggest an inverse relationship between the level of cGMP and the rate of tyrosine aminotransferase degradation in hepatocytes.
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Crettaz M, Kahn CR, Fehlmann M. Glucagon regulation of amino acid transport in hepatocytes: effect of cell enucleation. J Cell Physiol 1983; 115:186-90. [PMID: 6302105 DOI: 10.1002/jcp.1041150213] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Glucagon and cAMP analogs stimulate amino acid transport in freshly isolated hepatocytes by inducing the synthesis of new transport proteins. The role of the cell nucleus in the glucagon regulation of amino acid transport has been studied in rat hepatocytes enucleated by centrifugation through a discontinuous Ficoll gradient in the presence of cytochalasin B. Enucleated hepatocytes take up alpha-aminoisobutyric acid (AIB) through a Na+-dependent transport component with kinetic properties similar to those found in intact hepatocytes. Cytoplasts prepared from glucagon-stimulated cells retain the increase AIB transport induced by the hormone in the intact cells. The direct addition of glucagon to cytoplasts has no effect on AIB transport, in spite of the fact that the cytoplasts exhibit a higher capacity to bind glucagon than their nucleated counterparts. These data indicate that the nucleus is required for the glucagon stimulation of amino acid transport in isolated hepatocytes.
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Gómez-Lechón MJ, García MD, Castell JV. Effect of glucocorticoids on the expression of gamma-glutamyltransferase and tyrosine aminotransferase in serum-free-cultured hepatocytes. HOPPE-SEYLER'S ZEITSCHRIFT FUR PHYSIOLOGISCHE CHEMIE 1983; 364:501-8. [PMID: 6135659 DOI: 10.1515/bchm2.1983.364.1.501] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Glucocorticoids exert a known beneficial effect on cultured hepatocytes when present in culture medium, maintaining their polygonal morphology and ultrastructural organization throughout the days of culture. Parallel to this excellent morphology, hepatocytes cultured in serum-free conditions, but with continuous presence of Dexamethasone, retained after a week the ability to express tyrosine aminotransferase when stimulated by glucagon and glucocorticoids. The rise of gamma-glutamyltransferase was blocked in cultures supplemented by Dexamethasone.
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Widman LE, Chasin LA. Multihormonal induction of alpha 2u-globulin in an established rat hepatoma cell line. J Cell Physiol 1982; 112:316-26. [PMID: 6182149 DOI: 10.1002/jcp.1041120303] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A subclone of the FU5-5 rat hepatoma cell line has been isolated which is inducible more than several hundred fold for the 20,000 dalton form of the major rat urinary protein alpha 2u-globulin. The basal relative synthetic rate (RSR) in growth medium containing 10% fetal calf serum was less than 2 X 10(-6) of total protein synthesis. Both dexamethasone and insulin were necessary for induction, and yielded a maximum induced RSR of 4-8 X 10(-3). Triiodothyronine (T3), dihydrotestosterone (DHT), rat growth hormone (GH), and estrogen, all of which have been shown to influence the induction of alpha 2u-globulin in the intact rat, were without effect on the cell line. A factor present in fetal calf serum was also necessary for maximum induction, since dexamethasone plus insulin in serum-free medium raised the RSR to only 3 X 10(-5); exogenous T3, GH, and DHT could not substitute for this serum factor. The kinetics of induction by dexamethasone were slow, with a lag of approximately 48 hr followed by a period of increasing RSR for 6-20 days. Removal of dexamethasone from induced cells led to an exponential decline in the RSR (t 1/2 15 hr). The concentrations of dexamethasone and insulin that could yield half maximum induction were 5 X 10(-8)M and 3 X 10(-11)M, respectively. Higher concentrations of insulin, although still in physiological range (10(-9)M), inhibited induction. At yet higher insulin levels, beyond the physiological range, alpha 2u-globulin synthesis returned to maximum values. The lack of DHT, T3, and GH requirement for alpha 2u-globulin induction in this cell line may mean that a regulatory aberrancy has occurred in this transformed cell line, or, alternatively, that these hormones act indirectly in the intact animal. This cell line should prove useful for the study of the molecular events associated with alpha 2u-globulin induction and for genetic approaches to the problem of multihormonal regulation of gene expression.
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Abstract
Tyrosine aminotransferase induction has been studied in hepatocytes from untreated, partially and fully glucocorticoid-induced rats: enzyme activities were initially 12.9 +/- 1.7 (n = 16), 41.4 +/- 3.2 (n = 6) and 117.9 +/- 10.5 (n = 7) munits/mg protein, respectively. Untreated or fully induced hepatocytes maintain initial levels, whereas partially induced hepatocytes increase their tyrosine aminotransferase activity even in the presence of actinomycin D. Fully induced hepatocytes possess a normal protein synthetizing machinery and the mechanisms to degrade selectively tyrosine aminotransferase. The effect of progesterone treatment is consistent with these cells retaining a high dexamethasone level. Glucagon induces tyrosine aminotransferase via its second messenger, cyclic AMP. This induction decreases dramatically with in vivo glucocorticoid treatment. Time courses and effects of inhibitors are consistent with these in vivo and in vitro treatments being alternative methods of inducing tyrosine aminotransferase by the same basic pretranslational step.
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18
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Ho KK, Cake MH, Yeoh GC, Oliver IT. Insulin antagonism of glucocorticoid induction of tyrosine aminotransferase in cultured foetal hepatocytes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 118:137-42. [PMID: 6116599 DOI: 10.1111/j.1432-1033.1981.tb05496.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Whereas dexamethasone is unable to induce the premature formation of hepatic tyrosine aminotransferase when administered to foetal rats in utero, the steroid can induce the enzyme in foetal rat liver if the liver is first removed from the environment in utero and grown in culture. Dexamethasone produced a significant induction of the enzyme at a concentration of 0.1 nM in cultured foetal hepatocytes, but for optimal induction the cells were exposed to 10 nM for 15 h. Growing the hepatocytes in the presence of physiological concentrations of insulin had no effect on the enzyme activity in control cells. However, the induction of the enzyme by dexamethasone was markedly diminished in the presence of insulin. This effect of insulin is both time-dependent and dose-dependent with significant inhibition being obtained with 1 nM insulin. Growing foetal hepatocytes in the presence of insulin has no effect on either the cellular level of glucocorticoid receptor or on the stability of dexamethasone-receptor complexes to undergo nuclear translocation suggesting that insulin inhibits some event subsequent to translocation. The results are discussed in relation to the postnatal appearance of tyrosine aminotransferase and suggest that the marked decline in the plasma concentration of insulin, that is known to occur at birth, is a major contributor to the postnatal induction of the enzyme.
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19
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Evans MI, Hager LJ, McKnight GS. A somatomedin-like peptide hormone is required during the estrogen-mediated induction of ovalbumin gene transcription. Cell 1981; 25:187-93. [PMID: 7023694 DOI: 10.1016/0092-8674(81)90243-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Expression of the ovalbumin gene in chicken oviduct explant cultures requires the presence of a somatomedin-like peptide hormone in addition to estrogen. Insulin, proinsulin and multiplication-stimulating activity (MSA) are equally active substitutes for this peptide hormone, and maximal induction requires about 0.5 micrograms/ml; fetal calf serum can partially substitute for these factors. The equipotency of insulin and proinsulin indicates that insulin receptors are not involved, and the activity of MSA suggests that the active receptor is specific for somatomedins. The permissive effect of the peptide factor occurs within 1-2 hr and is required for the initiation of estrogen-mediated transcription on the ovalbumin gene. In contrast, transcription from the conalbumin gene is fully induced by estrogen in the presence or absence of peptide factors or serum, despite the fact that these two egg white genes are both transcribed in the same cells in response to the same steroid hormones. We suggest that the interaction of a somatomedin with its membrane-bound receptor generates an intracellular signal that interacts specifically with the ovalbumin gene.
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21
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Marston FA, Dickson AJ, Pogson CI. Factors affecting induction of tyrosine aminotransferase in isolated rat liver cells. Mol Cell Biochem 1981; 34:59-64. [PMID: 6112664 DOI: 10.1007/bf02354853] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
1. The response of tyrosine aminotransferase activity in isolated liver cells has been studied under several conditions. 2. Activity is increased over a 5 h period by both glucagon and glucocorticoids in cells from adrenalectomized rats. The results do not support the view that glucagon action is dependent on preexposure of cells to steroid. 3. In cells from fed animals, significant stimulation is seen only when both glucagon and steroid are present together. 4. In cells from 48 h fasted rats steroid is effective, but glucagon is not significant so. 5. These anomalies are attributed to the differences in hormonal and nutritional status between the animals from which the cells are isolated.
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Hargrove JL, Volentine G, Granner DK. On the steroid requirement for induction of tyrosine aminotransferase by N6, O2'-dibutyryl cyclic AMP in hepatoma cells. JOURNAL OF STEROID BIOCHEMISTRY 1981; 14:101-8. [PMID: 6259447 DOI: 10.1016/0022-4731(81)90198-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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23
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Shinno H, Noda C, Tanaka K, Ichihara A. Induction of L-lysine-2-oxoglutarate reductase by glucagon and glucocorticoid in developing and adult rats: in vivo and in vitro studies. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 633:310-6. [PMID: 7011389 DOI: 10.1016/0304-4165(80)90190-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
L-Lysine-2-oxoglutarate reductase (EC 1.5.1.8, NADP) in the liver of adult rats increased 4-5 times when the animals were treated with alloxan. In diabetic rats injection of insulin or adrenalectomy prevented the increase in enzyme activity. The activity of the similar enzyme in kidney was not changed by these treatments. The enzyme activity in primary cultured adult rat hepatocytes was also induced by addition of dexamethasone and glucagon together, and glucagon could be replaced by dibutyryl cyclic AMP. Insulin inhibited the induction. The hormonal induction was also inhibited by actinomycin D and by cycloheximide. During development of rats, fetal liver showed very low activity, but the activity appeared on day 1 after birth and then increased rapidly, reaching the adult level by day 5. The activity of the kidney enzyme increased more slowly and reached adult level 1 month after birth. Intra-uterine injection of glucagon caused precocious induction of the liver enzyme in fetuses. These results indicate that the activity of L-lysine-2-oxoglutarate reductase in the adult liver and in part in neonatal liver also, in controlled by both glucagon and glucocorticoid.
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Chen CL, Feigelson P. Hormonal control of alpha 2u globulin synthesis and its mRNA in isolated hepatocytes. Ann N Y Acad Sci 1980; 349:28-45. [PMID: 6164324 DOI: 10.1111/j.1749-6632.1980.tb29512.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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25
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Gurr JA, Potter VR. The significance of differences between fresh cell suspensions and fresh or maintained monolayers. Ann N Y Acad Sci 1980; 349:57-66. [PMID: 6111977 DOI: 10.1111/j.1749-6632.1980.tb29514.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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26
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Nakamura T, Shinno H, Ichihara A. Insulin and glucagon as a new regulator system for tryptophan oxygenase activity demonstrated in primary cultured rat hepatocytes. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)43858-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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27
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Morrison MR, Pardue S, Prashad N, Croall DE, Brodeur R. Relative increase in polysomal mRNA for R1 cAMP-binding protein in neuroblastoma cells treated with 1,N6-dibutyryl-adenosine 3',-5'-phosphate. EUROPEAN JOURNAL OF BIOCHEMISTRY 1980; 106:463-72. [PMID: 6249578 DOI: 10.1111/j.1432-1033.1980.tb04593.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Polysomal RNAs were isolated from control neuroblastoma cells and those treated with 1,N6-dibutyrl-adenosine 3',5'-phosphate (Bt2cAMP) and translated in wheat germ lysates. Comparison of proteins synthesized in vitro on two-dimensional gel electrophoretograms showed that there was a specific induction in the synthesis of a protein, Mr 48000, by the polysomal RNAs from Bt2cAMP-treated cells. This protein was identified as the R1 cAMP-binding protein by its coelectrophoresis with unlabelled binding protein and by its specific retention on 8-(6-aminohexylamino)-adenosine 3',5'-phosphate linked to Sepharose. Quantification of the proteins synthesized in vitro with subsaturating inputs of polysomal RNAs showed that there was a 1.4--1.7-fold increase in the synthesis of the R1 cAMP-binding protein by polysomal RNAs isolated from Bt2cAMP-treated cells. There was a similar increase when purified polyadenylated mRNA populations were compared. showing there was no change in the ratio of adenylated to nonadenylated mRNAs in the induced mRNA population. There was no corresponding increase in the synthesis of the R2 cAMP-binding protein although the relative synthesis of several other proteins was also increased and the synthesis of actin and the alpha and beta-tubulin subunits was decreased. The increased levels of the R1 cAMP-binding protein found in Bt2cAMP-treated neuroblastoma cells are therefore partly caused by a specific accumulation of its mRNA on polysomes. The mRNA content of the cytoplasmic messenger ribonucleoprotein (mRNP) population of control cells was insufficient to account for this increase by a translocation of R1 mRNA from the mRNP to the polysome fraction in Bt2cAMP-treated cells. The increase in polysomal R1 mRNA is therefore caused by its increased transcription of post-transcriptional processing or its decreased rate of degradation in Bt2cAMP-treated cells. Although the R1 and R2 binding proteins have identical molecular weights and similar pI values, the specific induction of the mRNA for R1 cAMP-binding protein and the differential distribution of the R1 and R2 mRNAs between the polysomal and messenger ribonucleoprotein compartments show that these two cAMP-binding proteins are encoded by different mRNA populations.
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Bellemann P. Primary monolayer culture of liver parenchymal cells and kidney cortical tubules as a useful new model for biochemical pharmacology and experimental toxicology. Studies in vitro on hepatic membrane transport, induction of liver enzymes, and adaptive changes in renal cortical enzymes. Arch Toxicol 1980; 44:63-84. [PMID: 6104478 DOI: 10.1007/bf00303184] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Freshly isolated liver parenchymal cells were maintained in either short-term monolayer, suspension of long-term monolayer culture. Rapidly occurring processes through hepatocellular membrane, e.g., the enhanced amino acid transport and the concomitantly increased potassium influx following progressive starvation, were kinetically evaluated best in short-term monolayer culture. The inducibility of tyrosine aminotransferase by glucagon, dexamethasone, and a combination of both was compared in suspension and in monolayer culture. The induction of slowly inducible foreign compound-metabolizing enzymes, (e.g., ethoxycoumarin-O-dealkylase, p-nitroanisole-O-demethylase, and UDP-glucuronyltransferase) by phenobarbital, 3-methylcholanthrene, and dexamethasone were studied in long-term monolayer culture. The latter system was also used to maintain isolated kidney cortical tubules for the investigation of renal enzyme adaptation during progressive time in culture.
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Gurr JA, Potter VR. Independent induction of tyrosine aminotransferase activity by dexamethasone and glucagon in isolated rat liver parenchymal cells in suspension and in monolayer culture in serum-free media. Exp Cell Res 1980; 126:237-48. [PMID: 6102037 DOI: 10.1016/0014-4827(80)90490-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Karakash C, Rohner-Jeanrenaud F, Hustvedt BE, Jeanrenaud B. Nitrogen handling in adult hypothalamic obese rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1980; 238:E32-7. [PMID: 7356014 DOI: 10.1152/ajpendo.1980.238.1.e32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Several aspects of nitrogen metabolism have been studied in adult nonhyperphagic, hyperinsulinemic, ventromedial hypothalamus (VMH)-lesioned rats. Ten days postoperatively, VMH-lesioned rats had high plasma levels of urea and low plasma tyrosine, while plasma alanine, glutamine, total amino acid, and protein levels were unaltered. Urea production and excretion were increased in VMH-lesioned rats. Increased urea synthesis could not be attributed to enhanced peripheral release of amino acids. In vitro, measurements of hepatic amino acid uptake and liver protein synthesis did not reveal any disturbances of these processes in VMH-lesioned rats. However, hepatic transamination and lipogenesis from amino acids were increased following VMH-lesions. In addition to the hyperinsulinemia previously reported to occur in nonhyperphagic VMH-lesioned rats, this study showed an increased glucagon secretion from perfused pancreases of these animals. These data together suggest that the excess of the two hormones at the portal vein of VMH-lesioned rats would favor uptake and deamination of amino acids, their diversion to lipid synthesis and possibly other pathways, with consequent increase in urea production and reduced supply of amino acids to peripheral tissues available for nitrogen retention.
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Suleiman S, Vestling C. Hormonal effects on the biosynthesis of lactate dehydrogenase in rat hepatocytes. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(19)86565-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Coordinated modulation of albumin synthesis and mRNA levels in cultured hepatoma cells by hydrocortisone and cyclic AMP analogs. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(19)83528-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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34
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Mizushima Y, Ishikawa M. The role of glucocorticoids in the regulation of glucose-6-phosphatase activity in fetal rat liver. Biochem Pharmacol 1979; 28:2279-83. [PMID: 227405 DOI: 10.1016/0006-2952(79)90690-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Wangh LJ, Osborne JA, Hentschel CC, Tilly R. Parenchymal cells purified from Xenopus liver and maintained in primary culture synthesize vitellogenin in response to estradiol-17 beta and serum albumin in response to dexamethasone. Dev Biol 1979; 70:479-99. [PMID: 383554 DOI: 10.1016/0012-1606(79)90040-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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36
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Monder C, Coufalik AH. Stimulation of tyrosine aminotransferase of fetal rat liver by cortisol, 17,21-dihydroxy-pregn-4-en-3,20-dione (11-deoxycortisol) and 11-deoxycorticosterone: synergistic interactions with dibutyryl cyclic AMP. FEBS Lett 1979; 102:169-72. [PMID: 37121 DOI: 10.1016/0014-5793(79)80952-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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37
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Ernest MJ, Feigelson P. Multihormonal control of tyrosine aminotransferase in isolated liver cells. MONOGRAPHS ON ENDOCRINOLOGY 1979; 12:219-41. [PMID: 40115 DOI: 10.1007/978-3-642-81265-1_12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The regulation of tyrosine aminotransferase activity by glucocorticoids and cyclic AMP was investigated in isolated liver parenchymal cell suspensions. The induction and maintenance of elevated levels of tyrosine aminotransferase activity in liver cells were completely dependent upon the presence of both the synthetic glucocorticoid, dexamethasone, and glucagon of dibutyryl cyclic AMP. No induction was observed when any of these compounds were tested alone. Immunotitration experiments revealed that the 6- to 7-fold increase in tyrosine aminotransferase activity following the addition of dexamethasone and glucagon was accompanied by a parallel increase in the amount of immunologically reactive enzyme protein. Pulse-labeling experiments established that this increase in enzyme protein could be fully accounted for by a corresponding increase in rate of synthesis of tyrosine aminotransferase. Neither hormone had any effect on the rate of degradation of the enzyme. The increase in tyrosine aminotransferase synthesis evoked by the presence of both hormones was blocked by the addition of actinomycin D or cycloheximide to the medium, demonstrating that RNA and protein synthesis were required for the induction of enzyme activity. By varying the time and order of addition of the inducers and inhibitions, evidence was obtained that the hormones act sequentially. The steroid hormone acts first, presumably to increase the level of functional tyrosine aminotransferase mRNA or its precursor. The processing of this precursor to a translatable form or the specific translation of tyrosine aminotransferase mRNA is apparently dependent upon a specific cyclic AMP-controlled process. In vivo experiments demonstrated that both glucocorticoids and cyclic AMP increase the level of functional tyrosine aminotransferase mRNA in the liver. The actions of the steroid hormone and cyclic nucleotide were blocked by alpha amanitin, establishing the requirement for ongoing gene transcription. The protein synthesis inhibitors, cycloheximide, emetine, and puromycin, were as effective as cyclic AMP in increasing tyrosine aminotransferase mRNA activity. The action of these inhibitors is probably related to their ability to elevate hepatic intracellular cyclic AMP levels, thus mimicking cyclic AMP administration. Extension of these in vivo studies to isolated liver cells will provide a valuable system for investigating the regulation of gene expression by glucocorticoids and cyclic AMP.
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Abstract
Mouse kidney beta-glucuronidase production is under multihormonal control. In normal mice, kidney glucuronidase is induced over 100-fold by testosterone. However, hypophysectomy reduces this induction to about 5% of normal. This loss in inducibility was in part restored by growth hormone. Simultaneous administration to hypophysectomized female mice of growth hormone and testosterone, but not of prolactin and testosterone, restored kidney glucuronidase concentration to half that found in testosterone-treated normal female mice. Growth hormone alone had no effect in hypophysectomized females nor did it enhance glucuronidase activity in testosterone-treated normal females. Radiolabeling experiments demonstrated that the enhancement by growth hormone of glucuronidase activity was accompanied by a corresponding increase in its rate of synthesis. Kidney hypertrophy and kidney glucuronidase production may be under common hormonal regulation. Testosterone or growth hormone treatment alone of hypophysectomized mice had little or no effect on either process, but combined treatment with the two hormones significantly enhanced both. The rate of synthesis of kidney glucuronidase is controlled by the Gur gene. Relative differences in kidney glucuronidase synthesis in mice of different Gur genotype were maintained in testosterone-treated hypophysectomized mice. This suggests that control of glucuronidase synthesis by the Gur locus is exerted by interaction with androgens rather than pituitary products.
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Glucocorticoid induction of alpha2u-globulin protein synthesis and its mRNA in rat hepatocytes in vitro. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)34453-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Failla ML, Cousins RJ. Zinc accumulation and metabolism in primary cultures of adult rat liver cells. Regulation by glucocorticoids. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 543:293-304. [PMID: 708788 DOI: 10.1016/0304-4165(78)90047-8] [Citation(s) in RCA: 138] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Adult rat liver parenchymal cells were isolated by the collagenase perfusion technique and cultured as a monolayer for up to 20 h. The quantity of zinc accumulated from the extracellular environment was significantly increased by adding physiological concentrations of certain glucocorticosteroids to the medium. The degree of stimulation was directly related to glucocorticoid potency. Sex steroids, certain peptide hormones and prostaglandins E2 and F2alpha did not influence zinc accumulation. Control cells exhibited a decline of zinc accumulation after 4 h in culture although uptake processes were still operative. When dexamethasone, the most potent glucocorticoid used, was present in the medium the cells accumulated zinc at a linear rate greater than that seen in control cells, for at least 20 h. The dexamethasone-induced stimulation of zinc accumulation was relatively specific since 45Ca, 14C-labelled amino acids and [35S]cystine accumulation was not influenced by the hormone. A lag of 4 h was observed before an effect of dexamethasone on zinc accumulation could be detected. Moreover, the hormone-stimulated phase of accumulation was blocked when the cells were simultaneously incubated with either actinomycin D or cycloheximide. The additional complement of zinc accumulated by the dexamethasone-treated cells was localized in the cytosol fraction. Gel filtration and ion-exchange chromatography confirmed that this additional cytosol zinc was bound to metallothionein. [35S]Cystine was incorporated into metallothionein in hormone-treated cells indicating that the protein was synthesized de novo during periods of enhanced zinc accumulation.
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DeLap L, Feigelson P. Effect of cycloheximide on the induction of tryptophan oxygenase mRNA by hydrocortisone in vivo. Biochem Biophys Res Commun 1978; 82:142-9. [PMID: 666903 DOI: 10.1016/0006-291x(78)90588-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Breen G, McGinnis J, de Vellis J. Modulation of the hydrocortisone induction of glycerol phosphate dehydrogenase by N6,O2'-dibutyryl cyclic AMP, norepinephrine, and isobutylmethylxanthine in rat brain cell cultures. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)40857-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Noguchi T, Diesterhaft M, Granner D. Dibutyryl cyclic AMP increases the amount of functional messenger RNA coding for tyrosine aminotransferase in rat liver. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)34869-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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45
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Ernest M, Feigelson P. Increase in hepatic tyrosine aminotransferase mRNA during enzyme induction by N6,O2'-dibutyryl cyclic AMP. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)38203-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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