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Suzuki T, Abe S, Yamaguchi M, Baba A, Hori T, Shiraishi H, Ito T. Effects of cocaine administration on receptor binding and subunits mRNA of GABA(A)-benzodiazepine receptor complexes. Synapse 2000; 38:198-215. [PMID: 11018794 DOI: 10.1002/1098-2396(200011)38:2<198::aid-syn11>3.0.co;2-k] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effects of intermittent intraperitoneal (i.p.) administration of cocaine (20 mg/kg) on GABA(A)-benzodiazepine (BZD) receptors labeled by t-[(35)S]butylbicyclophosphorothionate (TBPS), and on several types of mRNA subunits were investigated in rat brain by in vitro quantitative receptor autoradiography and in situ hybridization. Phosphor screen imaging with high sensitivity and a wide linear range of response was utilized for imaging analysis. There was a significant decrease in the level of alpha 1, alpha 6, beta 2, beta 3, and gamma 2 subunits mRNA, with no alteration of [(35)S]TBPS binding in any regions in the brain of rats at 1 h following a single injection of cocaine. In chronically treated animals, the mean scores of stereotyped behavior were increased with the number of injections. The level of beta 3 subunit mRNA was decreased in the cortices and caudate putamen, at 24 h after a final injection of chronic administrations for 14 days. In the withdrawal from cocaine, the frontal cortex and hippocampal complexes showed a significant increase in [(35)S]TBPS binding and alpha1 and beta 3 subunit mRNA in the rats 1 week after a cessation of chronic administration of cocaine. These findings suggest that the disruption of GABA(A)-BZD receptor formation is closely involved in the development of cocaine-related behavioral disturbances. Further studies on the physiological functions on GABA(A)-BZD receptor complex will be necessary for an explanation of the precise mechanisms underlying the acute effects, development of hypersensitization, and withdrawal state of cocaine.
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Affiliation(s)
- T Suzuki
- Department of Psychiatry, Institute of Clinical Medicine, University of Tsukuba, Tennodai, Tsukuba, Japan.
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Collins S, Quarmby VE, French FS, Lefkowitz RJ, Caron MG. Regulation of the beta 2-adrenergic receptor and its mRNA in the rat ventral prostate by testosterone. FEBS Lett 1988; 233:173-6. [PMID: 2838324 DOI: 10.1016/0014-5793(88)81378-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
To investigate the regulation of beta 2AR expression in rat ventral prostate the effects of castration and testosterone replacement on the beta 2AR were studied by ligand binding and Northern blot analysis. Orchidectomy depressed beta 2AR number by 50% within 4 days and testosterone administration to 4-day castrates produced a rapid and complete recovery of beta 2AR number within 24 h. In contrast to receptor number, beta 2AR mRNA levels did not change relative to total RNA following castration. However, during the testosterone replacement period beta 2AR mRNA levels rose transiently, reaching a maximum (3.5-fold) between 8 and 12 h, and this increase in mRNA preceded the recovery in beta 2AR number in the membrane. Regulation of beta 2AR gene expression by testosterone in the ventral prostate is thus complex and probably involves both transcriptional and post-transcriptional components.
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Affiliation(s)
- S Collins
- Department of Medicine (Cardiology), Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710
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Büchler W, Walter U, Jastorff B, Lohmann SM. Catalytic subunit of cAMP-dependent protein kinase is essential for cAMP-mediated mammalian gene expression. FEBS Lett 1988; 228:27-32. [PMID: 2830134 DOI: 10.1016/0014-5793(88)80577-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cyclic AMP-stimulated mRNA levels in cultured rat hepatocytes were inhibited by three different inhibitors of cAMP-dependent protein kinase activity: (i) Rp-cAMPS, a cAMP analog with a sulfur substitution at the equatorial oxygen of the cyclic monophosphate; (ii) H8, an isoquinoline sulfonamide derivative; and (iii) PKI, a 20-amino acid synthetic peptide of the Walsh protein kinase inhibitor. These inhibitors specifically blocked the cAMP-stimulated increase in mRNA for tyrosine aminotransferase and phosphoenolpyruvate carboxykinase; they had no effect on the level of albumin mRNA which is not cAMP regulated. These results provide functional evidence that kinase activity involving protein phosphorylation is required in cAMP-mediated gene expression in mammalian cells.
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Affiliation(s)
- W Büchler
- Labor für Klinische Biochemie, Medizinische Universitätsklinik, Würzburg, FRG
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Aouani A, Hovsépian S, Fayet G. cAMP dependent and independent regulation of thyroglobulin synthesis by two clones of the OVNIS 6H thyroid cell line. Mol Cell Endocrinol 1987; 52:151-60. [PMID: 3040495 DOI: 10.1016/0303-7207(87)90108-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The hormonal regulation of thyroglobulin synthesis has been studied using two independent clones of the OVNIS 6H cell line. Insulin, hydrocortisone and TSH were able to stimulate thyroglobulin synthesis, whereas transferrin, somatostatin and glycyl-histidyl-lysine were without effect. Insulin stimulated thyroglobulin synthesis without affecting cAMP production. Hydrocortisone, when combined with insulin was a stimulator too; this stimulation was not accompanied by an increase in cAMP. TSH alone was unable to stimulate either cAMP or thyroglobulin synthesis. The stimulatory effect of TSH on thyroglobulin synthesis took place only when combined with insulin or insulin plus hydrocortisone, and was mediated by cAMP. Consequently, insulin and hydrocortisone stimulated thyroglobulin synthesis by cAMP-independent mechanisms, whereas TSH acted via the cAMP system. Forskolin mimicked TSH effects on cAMP and thyroglobulin synthesis. Calf serum inhibited cAMP and thyroglobulin production. Optimal cAMP and thyroglobulin synthesis as well as TSH responsiveness were obtained in serum-free medium supplemented with 5 micrograms/ml insulin, 100 nM hydrocortisone and 1 mU/ml TSH.
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Morris SM, Moncman CL, Rand KD, Dizikes GJ, Cederbaum SD, O'Brien WE. Regulation of mRNA levels for five urea cycle enzymes in rat liver by diet, cyclic AMP, and glucocorticoids. Arch Biochem Biophys 1987; 256:343-53. [PMID: 3038025 DOI: 10.1016/0003-9861(87)90455-3] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Adaptive changes in levels of urea cycle enzymes are largely coordinate in both direction and magnitude. In order to determine the extent to which these adaptive responses reflect coordinate regulatory events at the pretranslational level, measurements of hybridizable mRNA levels for all five urea cycle enzymes were carried out for rats subjected to various dietary regimens and hormone treatments. Changes in relative abundance of the mRNAs in rats with varying dietary protein intakes are comparable to reported changes in enzyme activities, indicating that the major response to diet occurs at the pretranslational level for all five enzymes and that this response is largely coordinate. In contrast to the dietary changes, variable responses of mRNA levels were observed following intraperitoneal injections of dibutyryl cAMP and dexamethasone. mRNAs for only three urea cycle enzymes increased in response to dexamethasone. Levels of all five mRNAs increased severalfold in response to dibutyryl cAMP at both 1 and 5 h after injection, except for ornithine transcarbamylase mRNA which showed a response at 1 h but no response at 5 h. Combined effects of dexamethasone and dibutyryl cAMP were additive for only two urea cycle enzyme mRNAs, suggesting independent regulatory pathways for these two hormones. Transcription run-on assays revealed that transcription of at least two of the urea cycle enzyme genes--carbamylphosphate synthetase I and argininosuccinate synthetase--is stimulated approximately four- to fivefold by dibutyryl cAMP within 30 min. The varied hormonal responses indicate that regulatory mechanisms for modulating enzyme concentration are not identical for each of the enzymes in the pathway.
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Exton JH. Mechanisms of hormonal regulation of hepatic glucose metabolism. DIABETES/METABOLISM REVIEWS 1987; 3:163-83. [PMID: 3032541 DOI: 10.1002/dmr.5610030108] [Citation(s) in RCA: 116] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Acute hormonal regulation of liver carbohydrate metabolism mainly involves changes in the cytosolic levels of cAMP and Ca2+. Epinephrine, acting through beta 2-adrenergic receptors, and glucagon activate adenylate cyclase in the liver plasma membrane through a mechanism involving a guanine nucleotide-binding protein that is stimulatory to the enzyme. The resulting accumulation of cAMP leads to activation of cAMP-dependent protein kinase, which, in turn, phosphorylates many intracellular enzymes involved in the regulation of glycogen metabolism, gluconeogenesis, and glycolysis. These are (1) phosphorylase b kinase, which is activated and, in turn, phosphorylates and activates phosphorylase, the rate-limiting enzyme for glycogen breakdown; (2) glycogen synthase, which is inactivated and is rate-controlling for glycogen synthesis; (3) pyruvate kinase, which is inactivated and is an important regulatory enzyme for glycolysis; and (4) the 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase bifunctional enzyme, phosphorylation of which leads to decreased formation of fructose 2,6-P2, which is an activator of 6-phosphofructo-1-kinase and an inhibitor of fructose 1,6-bisphosphatase, both of which are important regulatory enzymes for glycolysis and gluconeogenesis. In addition to rapid effects of glucagon and beta-adrenergic agonists to increase hepatic glucose output by stimulating glycogenolysis and gluconeogenesis and inhibiting glycogen synthesis and glycolysis, these agents produce longer-term stimulatory effects on gluconeogenesis through altered synthesis of certain enzymes of gluconeogenesis/glycolysis and amino acid metabolism. For example, P-enolpyruvate carboxykinase is induced through an effect at the level of transcription mediated by cAMP-dependent protein kinase. Tyrosine amino-transferase, serine dehydratase, tryptophan oxygenase, and glucokinase are also regulated by cAMP, in part at the level of specific messenger RNA synthesis. The sympathetic nervous system and its neurohumoral agonists epinephrine and norepinephrine also rapidly alter hepatic glycogen metabolism and gluconeogenesis acting through alpha 1-adrenergic receptors. The primary response to these agonists is the phosphodiesterase-mediated breakdown of the plasma membrane polyphosphoinositide phosphatidylinositol 4,5-P2 to inositol 1,4,5-P3 and 1,2-diacylglycerol. This involves a guanine nucleotide-binding protein that is different from those involved in the regulation of adenylate cyclase. Inositol 1,4,5-P3 acts as an intracellular messenger for Ca2+ mobilization by releasing Ca2+ from the endoplasmic reticulum.(ABSTRACT TRUNCATED AT 400 WORDS)
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Stanfeld J, Jones J, Laster L, Davidovitch Z. Biochemical aspects of orthodontic tooth movement. I. Cyclic nucleotide and prostaglandin concentrations in tissues surrounding orthodontically treated teeth in vivo. Am J Orthod Dentofacial Orthop 1986; 90:139-48. [PMID: 3017094 DOI: 10.1016/0889-5406(86)90046-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The objective of this study was to extract and assay cyclic nucleotides and prostaglandins from tissues surrounding orthodontically treated canines in cats. Seven groups of three to five female cats were treated by 80 g tipping force to one maxillary canine for 0 to 28 days. Tissue samples were removed from sites of compression and tension around treated teeth, and from the corresponding control sites. Cyclic nucleotides and prostaglandins were simultaneously extracted by a solvent system at 0 to -5 degrees C. A portion of the aqueous fraction was used for cAMP assay by a binding protein method; cGMP was purified by column chromatography and measured by radioimmunoassay. The solvent fraction was dried, reconstituted with assay buffer, and each of the prostaglandins measured by radioimmunoassay. Analysis of variance showed no significant differences between summary control and treated sites at each of the time periods studied. However, when interactions at secondary and tertiary levels were considered (such as tension and compression, position [apical-gingival sites] of tissue sample, and jaws), significant differences were found in PGE, cAMP, and PGF2 alpha values. These results demonstrate that alterations in the levels of each of these substances in tissues surrounding teeth may be brought about by long-term applications of orthodontic force in vivo. The method of tissue sampling, however, does not permit measurement of the levels of these substances in target cells alone, thus diluting the acute response that may have occurred in these cells.
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Ball KL, Speake BK, Robinson DS. Effects of adrenaline on the turnover of lipoprotein lipase in rat adipose tissue. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 877:399-405. [PMID: 3015219 DOI: 10.1016/0005-2760(86)90205-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The mechanisms by which adrenaline brings about a reduction in the lipoprotein lipase activity of adipose tissue in vitro were investigated. The incorporation of [3H]leucine into lipoprotein lipase was measured during 1-h pulse incubations of rat epididymal fat bodies that had been preincubated for 4 h in the presence of glucose, insulin and dexamethasone. When adrenaline was added to the incubation medium at the start of the pulse, the incorporation of [3H]leucine was markedly reduced, suggesting that the rate of the enzyme's synthesis had decreased. On the other hand, the degradation of lipoprotein lipase, as measured by the loss of 3H-labelled enzyme protein during pulse-chase incubations of the epididymal fat bodies, was found to be significantly increased by the addition of adrenaline to the incubation medium at the start of the chase period. It is concluded that adrenaline is able both to inhibit the synthesis of lipoprotein lipase and to stimulate its degradation.
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Seetharam S, Sussman NL, Komoda T, Alpers DH. The mechanism of elevated alkaline phosphatase activity after bile duct ligation in the rat. Hepatology 1986; 6:374-80. [PMID: 3710426 DOI: 10.1002/hep.1840060307] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Alkaline phosphatase activity in the liver and intestine increases after bile duct ligation, reportedly by increased enzyme synthesis. To ascertain the mechanism of this increased synthesis in the absence of a cDNA clone encoding the enzyme, we have estimated the concentration of liver and intestinal alkaline phosphatase mRNA by translational analysis. Monospecific antiserum to rat placental alkaline phosphatase was raised. The resulting antiserum precipitated two peptides of 53 and 56 kd after translation of liver poly(A) + RNA. The precipitation of both peptides was blocked by the single 64 kd placental alkaline phosphatase. Processing of the cell-free products by microsomal membranes produced peptides of 62 and 64 kd. Antiserum to rat intestinal alkaline phosphatase also identified two peptides as products of intestinal RNA translation. After bile duct ligation, we confirmed a transient 2-fold increase in alkaline phosphatase activity in the intestine and a more constant 7-fold increase in the liver. However, the alkaline phosphatase mRNA concentration remained unchanged in both organs. We conclude that increased alkaline phosphatase synthesis after bile duct ligation results from an enhanced rate of translation of mRNA.
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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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de Groot CJ, Zonneveld D, de Laaf RT, Dingemanse MA, Mooren PG, Moorman AF, Lamers WH, Charles R. Developmental and hormonal regulation of carbamoyl-phosphate synthase gene expression in rat liver: evidence for control mechanisms at different levels in the perinatal period. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 866:61-7. [PMID: 3947635 DOI: 10.1016/0167-4781(86)90101-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Carbamoyl-phosphate synthase gene expression is found to be primarily regulated by conditions that enhance hepatic glucocorticosteroid levels (hormone injections) and cyclic AMP levels (induction of diabetes). After birth, changes in the level of carbamoyl-phosphate synthase protein follow changes in the level of carbamoylphosphate synthase mRNA, suggesting a pretranslational control mechanism. In fetal rats, carbamoyl-phosphate synthase gene expression is regulated by the same factors as in adults. However, both the level to which carbamoyl-phosphate synthase mRNA can accumulate and the extent to which mRNA can be translated appear to be limited, indicating control mechanisms at the pretranslational and translational level. Finally, in the immediate postnatal period, a transient but pronounced decrease in the rate of degradation of carbamoyl-phosphate synthase protein may play a role in the accumulation of the enzyme.
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Schwartz DA, Rubin CS. Identification and differential expression of two forms of regulatory subunits (RII) of cAMP-dependent protein kinase II in Friend erythroleukemic cells. Differentiation and 8-bromo-cAMP elicit a large and selective increase in the rate of biosynthesis of only one type of RII. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)88970-0] [Citation(s) in RCA: 47] [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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Harper JF, Haddox MK, Johanson RA, Hanley RM, Steiner AL. Compartmentation of second messenger action: immunocytochemical and biochemical evidence. VITAMINS AND HORMONES 1985; 42:197-252. [PMID: 3006347 DOI: 10.1016/s0083-6729(08)60063-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Lewis EJ, Tank AW, Weiner N, Chikaraishi DM. Regulation of tyrosine hydroxylase mRNA by glucocorticoid and cyclic AMP in a rat pheochromocytoma cell line. Isolation of a cDNA clone for tyrosine hydroxylase mRNA. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)43909-3] [Citation(s) in RCA: 182] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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15
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Pretranslational control of tyrosine aminotransferase synthesis by 8-bromo-cyclic AMP in H-4 rat hepatoma cells. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)43990-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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van Wijk R, Loesberg L, Snoek GT. Variations in some molecular events during the early phases of the Reuber H35 cell cycle. IV-regulation of tyrosine aminotransferase. Biochimie 1983; 65:643-52. [PMID: 6143573 DOI: 10.1016/s0300-9084(84)80028-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Tyrosine aminotransferase activity increased during conversion of serum depleted quiescent Reuber H35 rat hepatoma cells into the proliferative state. Increased activity coincides with the actual increase of cells into S phase. The rate of tyrosine aminotransferase synthesis along the cell cycle was studied. The rate of enzyme synthesis fluctuated through the cell cycle but could not explain the increase of specific activity. Apparently enzyme activity is predominantly regulated by a post-translational event. Intracellular levels of cyclic AMP and cyclic GMP were measured at various times of G1 and S phases. In the early part of the cell cycle tyrosine aminotransferase decreased while intracellular levels of cyclic AMP increased. At later stages cyclic AMP rises concurrently with increased rates of enzyme synthesis. Induction of tyrosine aminotransferase by N6,O2'-dibutyryladenosine 3', 5'-monophosphate (Bt2cAMP) was studied. Inducibility by Bt2cAMP fluctuated through the cell cycle. Alternation of positive and negative control of tyrosine aminotransferase synthesis was observed. In early serum induced cells, Bt2cAMP increased enzyme activity without any increased rate of enzyme synthesis, on the contrary, a decreased rate of synthesis was observed. The data support the view that alternation of positive and negative control of tyrosine aminotransferase synthesis and temporary post-translational control of enzyme activity determine the enzyme level during the transition of quiescent hepatoma cells into proliferation.
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Mueckler MM, Merrill MJ, Pitot HC. Translational and pretranslational control of ornithine aminotransferase synthesis in rat liver. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32379-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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18
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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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Chrapkiewicz NB, Beale EG, Granner DK. Induction of the messenger ribonucleic acid coding for phosphoenolpyruvate carboxykinase in H4-II-E cells. Evidence for a nuclear effect of cyclic AMP. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(19)45398-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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