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Guo XY, Fang YJ, Wu LY. Early Diet Dilution with 40% Rice Hull Induces Lower Body Fat and Lipid Metabolic Programming in Peking Ducks. Korean J Food Sci Anim Resour 2013. [DOI: 10.5851/kosfa.2013.33.3.341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Rosebrough RW, Russell BA, McMurtry JP. Studies on doses of methimazole (MMI) and its administration regimen on broiler metabolism. Comp Biochem Physiol A Mol Integr Physiol 2006; 143:35-41. [PMID: 16337159 DOI: 10.1016/j.cbpa.2005.10.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Revised: 10/11/2005] [Accepted: 10/12/2005] [Indexed: 11/20/2022]
Abstract
We designed three experiments to determine both the optimal dose of and time on experiment for methimazole (MMI; 1-methyl-2-mercaptimidazole). Our goals were to determine if chicken growth was related to thyroid hormone levels and if intermediary metabolism changed along with changes in thyroid hormone levels. Initiating MMI at one week of age decreased (P<0.01) plasma thyroid levels and growth in four-week old birds. In contrast, initiating MMI at two and three weeks of age decreased (P<0.05) hormone levels without affecting growth as severely. Although initiating MMI at two weeks of age depressed (P<0.05) plasma thyroid hormones at four weeks, there was little change in vitro lipogenesis at four weeks. Again, initiating MMI at one week of age decreased body weight, plasma thyroid hormones and in vitro lipogenesis at four weeks of age. In addition, this treatment also decreased (P<0.05) malic enzyme activity at this same age period. The second experiment showed that MMI, initiated at 14 days, had no significant effect on 28-day body weight and again decreased both plasma T(3) and T(4) but T(3) replacement increased plasma T(3) in both 14-28-day treatment groups. All body weights were similar at 30 days, however. Lastly, diets containing graded levels of MMI decreased thyroid hormones and body weight (0>0.25>0.5>1 g MMI/kg). In contrast, only the two higher levels (0.5 and 1 g MMI/kg) decreased in vitro lipogenesis. Growth depression, caused by MMI feeding, can occur without changes in lipid metabolism. The length of MMI administration may be as important as dose level in obtaining effects (growth, thyroid hormone depression and inhibition of lipogenesis).
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Affiliation(s)
- R W Rosebrough
- Growth Biology Laboratory, Animal and Natural Resources Institute, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705, USA.
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Abstract
Seven-day-old chickens were fed diets containing 18% crude protein + 0 or 1g methimazole/kg to produce either euthyroid or hypothyroid groups of birds at 28 days of age. These two groups were then offered diets containing either 0 or 1mg triiodothyronine (T(3))/kg diet. Birds were sampled at 0, 2, 5, and 8 days following the onset of the T(3) treatment. Measurements taken at these intervals included in vitro hepatic lipogenesis (IVL), growth and feed consumption, hepatic enzyme activities (malic enzyme, ME; isocitrate dehydrogenase, ICD; and aspartate amino transferase, AAT), plasma hormones (T(3); thyroxine, T(4); insulin like growth factors I, IGF-I; and insulin like growth factors II, IGF-II) and metabolites (glucose; fatty acids, NEFA; triglyerides; uric acid). Hypothyroidism decreased IVL and ME at 28 days of age; however, T(3) supplementation for 2 days restored both IVL and ME. Paradoxically, continuing T(3) replenishment for an additional 3-6 days decreased IVL without affecting ME activity. In contrast, supplemental T(3) decreased IVL in euthyroid birds, regardless of the dosing interval, but had no effect on ME activity. Methimazole decreased plasma T(3), T(4), uric acid, and IGF-I, but did not affect IGF-II at 28 days. Giving T(3) to birds previously on methimazole increased plasma IGF-I as did feeding a control diet. Supplemental T(3) increased NEFA in both euthyroid and hypothyroid birds, but only for a short period following the initiation of supplementation (2 days post-supplementation). These data may help to explain some of the apparent reported dichotomies in lipid metabolism elicited by changes in the thyroid state of animals. In addition, most metabolic changes in response to feeding T(3) occurred within 2-5 days, suggesting that changes in intermediary metabolism preceded morphological changes. In conclusion, the thyroid state of the animal will determine responses to exogenous T(3).
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Affiliation(s)
- R W Rosebrough
- Growth Biology Laboratory, Animal and Natural Resources Institute, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705, USA.
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Bee G. Dietary conjugated linoleic acid consumption during pregnancy and lactation influences growth and tissue composition in weaned pigs. J Nutr 2000; 130:2981-9. [PMID: 11110857 DOI: 10.1093/jn/130.12.2981] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We evaluated the effects of conjugated linoleic acid (CLA) on growth performance, tissue fatty acid composition and ex vivo lipogenic enzyme activity in piglets (n = 40) reared on sows fed diets supplemented with CLA or linoleic acid (LA). Weaned offspring of both sow groups were offered either a CLA- or LA-enriched starter diet for 35 d. The starter diets were formulated to contain 2 g CLA (containing 58.9 g CLA/100 g total fatty acids) or LA per 100 g feed. All piglets were slaughtered at 70 d of age and tissue samples of the back fat, omental fat and longissimus dorsi were collected. Irrespective of the dietary fat supplied in the starter period, piglets reared on the CLA sows had greater final body and warm carcass weights (P: < 0.01), and greater feed intake (P: = 0.02) than piglets reared on the LA sows. The dietary effect on the fatty acid composition was similar for the adipose and muscle tissues. Compared with the LA-enriched diets, CLA increased the level of total saturated fatty acids (P: < 0.05), whereas that of monounsaturated fatty acids was decreased (P: < 0.05). Dietary CLA increased glucose-6-phosphate dehydrogenase (P: < 0.01) and malic enzyme activities (P: < 0.06) in the fat tissues, but did not affect fatty acid synthase activity. The shift toward a higher deposition of saturated fatty acids and a lower deposition of monounsaturated fatty acids is the result of down-regulation of Delta9-desaturase activity that was induced by CLA rather than an altered rate of de novo synthesis.
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Affiliation(s)
- G Bee
- Swiss Federal Station for Animal Production, Posieux, 1725 Switzerland
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Rosebrough RW, McMurtry JP. Supplemental triiodothyronine, feeding regimens, and metabolic responses by the broiler chicken. Domest Anim Endocrinol 2000; 19:15-24. [PMID: 10962195 DOI: 10.1016/s0739-7240(00)00060-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There are conflicting results concerning the role of the thyroid hormones in lipid metabolism. The experiments in this report were designed to examine the role of T(3) in modifying responses obtained by shifting birds from moderate to low protein diets. Birds were grown from 7 to 28 d on a diet containing 18% protein. At this time, birds were switched to a diet containing 12% protein +/- T(3) The switch was accomplished either immediately or after a 24 hr fast. Measurements taken included in vitro lipogenesis (IVL), hepatic enzyme activities and plasma metabolites and thyroid hormones. Simply switching to birds to the low protein diet increased IVL, but rates were similar for three days following the switch. Feeding T(3) in this same regimen resulted in lower, but again, constant rates of IVL. In contrast, although switching protein levels after a 24 hr fast increased IVL, the rate after two days of refeeding was nearly double that following one day. This accentuated response was somewhat attenuated by including T(3) in the diet. Neither fasting nor refeeding altered plasma T(3) relative to ad libitum values. Supplemental dietary T(3) increased plasma T(3) and results were not affected by feeding regimens. Plasma T(4) was greatest in birds fasted for 24 hr and least in birds fed T(3) suggesting that feeding regimens may regulate the conversion of T(4) to T(3) It is suggested from this study that some of the effects of alterations in dietary feeding regimens can be modulated by T(3)
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Affiliation(s)
- R W Rosebrough
- Growth Biology Laboratory, Livestock and Poultry Science Institute, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705, USA.
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Xie Z, Li H, Liu L, Kahn BB, Najjar SM, Shah W. Metabolic regulation of Na(+)/P(i)-cotransporter-1 gene expression in H4IIE cells. Am J Physiol Endocrinol Metab 2000; 278:E648-55. [PMID: 10751198 DOI: 10.1152/ajpendo.2000.278.4.e648] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We showed that the rat Na(+)/P(i) cotransporter-1 (RNaPi-1) gene was regulated by insulin and glucose in rat hepatocytes. The aim of this work was to elucidate signaling pathways of insulin-mediated metabolic regulation of the RNaPi-1 gene in H4IIE cells. Insulin increased RNaPi-1 mRNA abundance in the presence of glucose and decreased RNaPi-1 mRNA in the absence of glucose, clearly establishing an involvement of metabolic signals for insulin-induced upregulation of the RNaPi-1 gene. Pyruvate and insulin increased RNaPi-1 expression but downregulated L-pyruvate kinase, indicating the existence of gene-specific metabolic signals. Although fructose, glycerol, and lactate could support insulin-induced upregulation of the RNaPi-1 gene, compounds entering metabolism beyond pyruvate oxidation, such as acetate and citrate, could not, suggesting that RNaPi-1-specific metabolic signals are generated at or above pyruvate oxidation. Wortmannin, LY-294002, and rapamycin abolished the insulin effect on the RNaPi-1 gene, whereas expression of dominant negative Asn(17) Ras and mitogen-activating protein kinase (MAPK) kinase (MEK) inhibitor PD-98059 exhibited no effect. Thus we herein propose that metabolic regulation of RNaPi-1 expression by insulin is mediated through the phosphatidylinositol 3-kinase/p70 ribosomal S6 kinase pathways, but not the Ras/MAPK pathway.
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Affiliation(s)
- Z Xie
- Department of Pharmacology, Medical College of Ohio, Toledo, Ohio 43614-5804, USA.
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Gibala MJ, Saltin B. PDH activation by dichloroacetate reduces TCA cycle intermediates at rest but not during exercise in humans. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:E33-8. [PMID: 10409125 DOI: 10.1152/ajpendo.1999.277.1.e33] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that dichloroacetate (DCA), which stimulates the pyruvate dehydrogenase complex (PDH), would attenuate the increase in muscle tricarboxylic acid cycle intermediates (TCAI) during exercise by increasing the oxidative disposal of pyruvate and attenuating the flux through anaplerotic pathways. Six subjects were infused with either saline (Con) or DCA (100 mg/kg body mass) and then performed a moderate leg kicking exercise for 15 min, followed immediately by intense exercise until exhaustion (Exh; approximately 4 min). Resting active fraction of PDH (PDH(a)) was markedly increased (P </= 0.05) after DCA vs. Con (2.65 +/- 0.27 vs. 0.64 +/- 0.07 mmol. min(-1). kg wet wt(-1)); however, there were no differences between trials after 1 or 15 min of exercise or at Exh. The sum of five measured TCAI (SigmaTCAI; approximately 90% of total TCAI pool) was lower (P </= 0.05) after DCA vs. Con at rest (0. 78 +/- 0.11 vs. 1.52 +/- 0.23 mmol/kg dry wt, respectively). However, the net increase in muscle TCAI during the first minute of exercise was higher (P </= 0.05) in the DCA trial vs. Con (3.05 +/- 0.45 vs. 2.44 +/- 0.55 mmol. min(-1). kg dry wt(-1), respectively), and consequently, the SigmaTCAI was not different between trials during exercise. We conclude that DCA reduced TCAI pool size at rest by increasing the flux through PDH and diverting pyruvate away from anaplerotic pathways. The reason for the similar absolute increase in TCAI during exercise is not clear but may be related to 1) an initial mismatch between glycolytic flux and PDH flux that provided sufficient pyruvate for anaplerosis in both trials; or 2) a transient inhibition of PDH flux during the DCA trial due to an elevated resting acetyl-CoA-to-CoASH ratio, which augmented the anaplerotic flux of carbon during the rest-to-work transition.
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Affiliation(s)
- M J Gibala
- Copenhagen Muscle Research Center, Rigshospitalet, DK-2200 Copenhagen N, Denmark.
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Konrad SD, Cook SL, Goh YK, French MA, Clandinin MT. Use of deuterium oxide to measure de novo fatty acid synthesis in normal subjects consuming different dietary fatty acid composition1. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1393:143-52. [PMID: 9714781 DOI: 10.1016/s0005-2760(98)00061-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effect of dietary linoleic (C18:2n-6) and palmitic acids (C16:0) on rate of hepatic de novo fatty acid synthesis was assessed in normal subjects. The diet was formulated to provide combinations of high and low levels of C18:2n-6 and C16:0. After 21 days of diet treatment, plasma triacylglycerol level and incorporation of deuterium into the plasma very low density lipoprotein triacylglycerol (VLDL-TG) pool over 24 hours was measured. Plasma triacylglycerol levels were within the normal range. Increasing dietary intake of linoleic acid decreased plasma triacylglycerol level when subjects consumed a low level of dietary palmitic acid. The relative and net amount of de novo synthesized fatty acid in the plasma VLDL-TG pool was not influenced by the diet treatments. A relationship between plasma triacylglycerol level and rate of hepatic de novo fatty acid synthesis was observed.
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Affiliation(s)
- S D Konrad
- Nutrition and Metabolism Research Group, University of Alberta, Edmonton, Alberta T6G 2P5, Canada
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Hillgartner FB, Charron T. Glucose stimulates transcription of fatty acid synthase and malic enzyme in avian hepatocytes. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:E493-501. [PMID: 9530133 DOI: 10.1152/ajpendo.1998.274.3.e493] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Transcription of fatty acid synthase (FAS) and malic enzyme (ME) in avian liver is low during starvation or feeding a low-carbohydrate, high-fat diet and high during feeding a high-carbohydrate, low-fat diet. The role of glucose in the nutritional control of FAS and ME was investigated by determining the effects of this metabolic fuel on expression of FAS and ME in primary cultures of chick embryo hepatocytes. In the presence of triiodothyronine, glucose (25 mM) stimulated an increase in the activity and mRNA abundance of FAS and ME. These effects required the phosphorylation of glucose to glucose 6-phosphate but not further metabolism downstream of the aldolase step of the glycolytic pathway. Xylitol mimicked the effects of glucose on FAS and ME expression, suggesting that an intermediate of the pentose phosphate pathway may be involved in mediating this response. The effects of glucose on the mRNA abundance of FAS and ME were accompanied by similar changes in transcription of FAS and ME. These data support the hypothesis that glucose plays a role in mediating the effects of nutritional manipulation on transcription of FAS and ME in liver.
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Affiliation(s)
- F B Hillgartner
- Department of Biochemistry, School of Medicine, West Virginia University, Morgantown 26506, USA
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Argaud D, Kirby TL, Newgard CB, Lange AJ. Stimulation of glucose-6-phosphatase gene expression by glucose and fructose-2,6-bisphosphate. J Biol Chem 1997; 272:12854-61. [PMID: 9139747 DOI: 10.1074/jbc.272.19.12854] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Glucose-6-phosphatase, a key enzyme in the homeostatic regulation of blood glucose concentration, catalyzes the terminal step in gluconeogenesis and glycogenolysis. Glucose, the product of the glucose-6-phosphatase reaction, dramatically increases the level of glucose-6-phosphatase mRNA transcripts in primary hepatocytes (20-fold), and the maximum response is obtained at a glucose concentration as low as 11 mM. Glucose specifically increases glucose-6-phosphatase mRNA and L-type pyruvate kinase mRNA. In the rat hepatoma-derived cell line, Fao, glucose increases the glucose-6-phosphatase mRNA only modestly (3-fold). In the presence of high glucose concentrations, overexpression of glucokinase in Fao cells via recombinant adenovirus vectors increases lactate production to the level found in primary hepatocytes and increases glucose-6-phosphatase gene expression by 21-fold. Similar overexpression of hexokinase I in Fao cells with high levels of glucose does not increase lactate production nor does it change the response of glucose-6-phosphatase mRNA to glucose. Glucokinase overexpression in Fao cells blunts the previously reported inhibitory effect of insulin on glucose-6-phosphatase gene expression in these cells. Raising the cellular concentration of fructose-2,6-bisphosphate, a potent effector of the direction of carbon flux through the gluconeogenic and glycolytic pathways, also stimulated glucose-6-phosphatase gene expression in Fao cells. Increasing the fructose-2,6-bisphosphate concentration over a 15-fold range (12 +/- 1 to 187 +/- 17 pmol/plate) via an adenoviral vector overexpression system, led to a 6-fold increase (0.32 +/- 0. 03 to 2.2 +/- 0.33 arbitrary units of mRNA) in glucose-6-phosphatase gene expression with a concomitant increase in glycolysis and a decrease in gluconeogenesis. Also, the effects of fructose-2, 6-bisphosphate concentrations on fructose-1,6-bisphosphatase gene expression were stimulatory, leading to a 5-6-fold increase in mRNA level over a 15-fold range in fructose-2,6-bisphosphate level. Liver pyruvate kinase and phosphoenolpyruvate carboxykinase mRNA were unchanged by the manipulation of fructose-2,6-bisphosphate level.
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Affiliation(s)
- D Argaud
- Department of Biochemistry, Medical School, University of Minnesota, Minneapolis, Minnesota 55455-0347, USA
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Abstract
Diets high in simple carbohydrates and low in fats lead in the mammalian liver to induction of a set of enzymes involved in lipogenesis. This induction occurs, in part, through transcriptional mechanisms that lead to elevated levels of the mRNA for these enzymes. For most of the lipogenic enzymes, an increase in glucose metabolism is required to trigger the transcriptional response. The intracellular mediator of this signaling pathway is unknown, although evidence suggests either glucose-6-phosphate or xylulose-5-phosphate. Studies to map the regulatory sequences of lipogenic enzyme genes involved in the transcriptional response have been performed for the L-type pyruvate kinase, S14, and acetyl-coenzyme A carboxylase genes. These studies have identified the DNA sequences necessary to link the signal generated by carbohydrate metabolism to specific nuclear transcription factors.
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Affiliation(s)
- H C Towle
- Department of Biochemistry and the Institute of Human Genetics, University of Minnesota, Minneapolis 55455, USA
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Affiliation(s)
- H C Towle
- Department of Biochemistry, University of Minnesota Medical School, Minneapolis 55455, USA
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Shih HM, Liu Z, Towle HC. Two CACGTG motifs with proper spacing dictate the carbohydrate regulation of hepatic gene transcription. J Biol Chem 1995; 270:21991-7. [PMID: 7665621 DOI: 10.1074/jbc.270.37.21991] [Citation(s) in RCA: 173] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Regulatory sequences involved in the transcriptional induction of the rat S14 gene in response to increased glucose metabolism in the hepatocyte were investigated and compared with those of the liver-type pyruvate kinase (L-PK) gene. The carbohydrate response element (ChoRE) of the S14 gene was found to consist of two motifs related to the consensus binding site for the c-myc family of transcription factors, CACGTG. These two motifs are separated by five base pairs, a similar arrangement to that found in the L-PK ChoRE. In its natural context, the S14 ChoRE requires a novel accessory factor to support the full response glucose. This factor, as well as the factor hepatic nuclear factor-4, are both capable of binding to the L-PK gene to enhance its carbohydrate regulation. The need for an accessory factor for supporting the glucose response can be overcome in two ways. First, multimers of the ChoREs of either the L-PK or S14 genes can function independently to support the glucose response. Second, mutations in the S14 ChoRE that create a perfect match to the consensus CACGTG motif at each locus no longer require an accessory factor site. The spacing of the two CACGTG motifs, but not the nature of the bases within the spacer, are critical for control. These observations suggest that a carbohydrate responsive factor binds to both motifs in a highly specific spatial orientation to confer the response to increased carbohydrate metabolism.
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Affiliation(s)
- H M Shih
- Department of Biochemistry, Medical School, University of Minnesota, Minneapolis 55455, USA
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Tomita Y, Abraham S, Noda C, Ichihara A. Pyruvate stimulates hormonal induction of lipogenic enzymes in primary cultured rat hepatocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1170:253-7. [PMID: 8218343 DOI: 10.1016/0005-2760(93)90007-v] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Hormonal inductions of lipogenic enzyme activities (fatty acid synthetase, malic enzyme (ME), glucose-6-phosphate dehydrogenase (G6PD) and ATP-citrate lyase) were studied in primary cultured rat hepatocytes. Insulin, triiodothyronine and dexamethasone markedly stimulated the inductions of the enzymes (particularly G6PD and ME) in the presence of pyruvate. Lactate also induced their activities. The activities of these enzymes in the presence of appropriate hormone combinations and a substrate amount of pyruvate were as high as, or higher than those in the liver of rats on high-carbohydrate, low-fat diet. The aldolase and glucokinase activities induced by these hormones were not enhanced by the addition of pyruvate. The induction by pyruvate was inhibited by actinomycin D or cycloheximide. The ATP content of rat hepatocytes was maintained without increase during culture with pyruvate for 6 days. These results indicate that the additions of pyruvate, or its metabolites to cultures of isolated hepatocytes have specific effects on the inductions of certain hepatic enzymes, possibly acting at the level of transcription. Their effects are similar to those of feeding a high-carbohydrate, low-fat diet to intact animals.
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Affiliation(s)
- Y Tomita
- Institute for Enzyme Research, University of Tokushima, Japan
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Schwartz H, Strait K, Oppenheimer J. Molecular Mechanisms of Thyroid Hormone Action: A Physiologic Perspective. Clin Lab Med 1993. [DOI: 10.1016/s0272-2712(18)30425-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Molero C, Benito M, Lorenzo M. Regulation of malic enzyme gene expression by nutrients, hormones, and growth factors in fetal hepatocyte primary cultures. J Cell Physiol 1993; 155:197-203. [PMID: 8468366 DOI: 10.1002/jcp.1041550125] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The culture of fetal hepatocytes for 64 h in medium supplemented with 5 mM glucose, T3, insulin, and dexamethasone resulted in the coordinate precocious expression of malic enzyme mRNA, protein, and specific activity. T3 was the main inducer; meanwhile, insulin exerted a small synergistic effect when added with T3. Dexamethasone had a potentiation effect on the T3 response of malic enzyme mRNA expression regardless of the presence of insulin. This effect of dexamethasone on T3 response of malic enzyme mRNA expression was time (64 h) and glucose dependent. Glucagon, and to a greater degree dibutyryl-cAMP, repressed malic enzyme mRNA as well as protein expression by T3 and dexamethasone, in the absence of insulin. Glucose and other carbon sources such as lactate-pyruvate or dihydroxyacetone induced the abundance of malic enzyme mRNA in the absence of hormones. Insulin and T3 produced a high accumulation of malic enzyme mRNA in lactate-pyruvate medium, this effect being decreased by dexamethasone. EGF suppressed the induction produced by T3 and dexamethasone on malic enzyme mRNA, while the expression of beta-actin mRNA remained essentially unmodified.
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Affiliation(s)
- C Molero
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
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Foufelle F, Gouhot B, Pégorier J, Perdereau D, Girard J, Ferré P. Glucose stimulation of lipogenic enzyme gene expression in cultured white adipose tissue. A role for glucose 6-phosphate. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)36717-1] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Shih H, Towle H. Definition of the carbohydrate response element of the rat S14 gene. Evidence for a common factor required for carbohydrate regulation of hepatic genes. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42198-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Mann DJ, Bailey E. Pre-translational control of hepatic malic enzyme expression during the development of the rat. Biochem J 1991; 279 ( Pt 2):407-12. [PMID: 1953638 PMCID: PMC1151619 DOI: 10.1042/bj2790407] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The expression of hepatic cytosolic malic enzyme in the developing rat has been studied by molecular-biological techniques. Malic enzyme mRNA was barely detectable throughout the neonatal period, but increased to significant levels immediately before weaning. Northern-blot analysis demonstrated that the two major malic enzyme mRNA species displayed non-co-ordinate control during development, with the 2.0 kb form accumulating to a greater extent than the 3.1 kb form. A novel 1.6 kb mRNA species was found to predominate in foetal samples. Tri-iodothyronine treatment of neonatal rats caused premature induction of all three malic enzyme mRNA species. Dietary studies also showed precocious induction of the mRNA with diets high in carbohydrate, but not with those high in fat.
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Affiliation(s)
- D J Mann
- Department of Molecular Biology and Biotechnology, University of Sheffield, U.K
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Matzen LE, Kristensen SR, Kvetny J. Triiodothyronine (T3)-associated upregulation and downregulation of nuclear T3 binding in the human fibroblast cell (MRC-5)--stimulation of malic enzyme, glucose-6-phosphate-dehydrogenase, and 6-phosphogluconate-dehydrogenase by insulin, but not by T3. Metabolism 1991; 40:657-63. [PMID: 1870419 DOI: 10.1016/0026-0495(91)90080-g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The specific nuclear binding of triiodothyronine (T3) (NBT3) and the activity of malic enzyme (ME), glucose-6-phosphate-dehydrogenase (G6PD), and 6-phosphogluconate-dehydrogenase (6PGD) were studied in the human fibroblast cell (MRC-5). The overall apparent binding affinity (Ka) was 2.7 x 10(9) L.mol-1 estimated from kinetic studies of nuclear T3 binding, and 2.5 x 10(9) L.mol-1 estimated from equilibrium studies. The scatchard plots were curvilinear and composed of a high-affinity binding site with Ka1 3.4 +/- 0.7 x 10(9) L.mol-1 and maximal binding capacity (MBC) MBC1 57.0 +/- 11.9 fmol/mg DNA and a low-affinity binding site with Ka2 2.9 +/- 1.1 x 10(8) L.mol-1 and MBC2 124.7 +/- 22.1 fmol/mg DNA (n = 6). Incubation of cells with 6 nmol/L T3 for 20 hours reduced NBT3 to 62.2% +/- 15.7% (P less than .01, n = 11). The Ka estimated from kinetic studies was reduced to 6.7 x 10(7) L.mol-1, and the scatchard plots were linear, with Ka 4.5 +/- 1.6 x 10(8) L.mol-1 and MBC 137.0 +/- 44.6 fmol/mg DNA (n = 3) of the same magnitude as the low-affinity binding site in cells incubated without T3 (NS). The reduction in NBT3 was reversible and maximal at T3 concentrations saturating the high-affinity binding site and more than 58% of the total nuclear binding sites. The MRC-5 cell cytosol contained ME, G6PD, and 6PGD activities.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L E Matzen
- Department of Clinical Chemistry, Odense University Hospital, Denmark
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22
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Jump DB, Bell A, Santiago V. Thyroid hormone and dietary carbohydrate interact to regulate rat liver S14 gene transcription and chromatin structure. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39792-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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23
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Abstract
Dichloroacetate (DCA) exerts multiple effects on pathways of intermediary metabolism. It stimulates peripheral glucose utilization and inhibits gluconeogeneis, thereby reducing hyperglycemia in animals and humans with diabetes mellitus. It inhibits lipogenesis and cholesterolgenesis, thereby decreasing circulating lipid and lipoprotein levels in short-term studies in patients with acquired or hereditary disorders of lipoprotein metabolism. By stimulating the activity of pyruvate dehydrogenase, DCA facilitates oxidation of lactate and decreases morbidity in acquired and congenital forms of lactic acidosis. The drug improves cardiac output and left ventricular mechanical efficiency under conditions of myocardial ischemia or failure, probably by facilitating myocardial metabolism of carbohydrate and lactate as opposed to fat. DCA may also enhance regional lactate removal and restoration of brain function in experimental states of cerebral ischemia. DCA appears to inhibit its own metabolism, which may influence the duration of its pharmacologic actions and lead to toxicity. DCA can cause a reversible peripheral neuropathy that may be related to thiamine deficiency and may be ameliorated or prevented with thiamine supplementation. Other toxic effects of DCA may be species-specific and reflect marked interspecies variation in pharmacokinetics. Despite its potential toxicity and limited clinical experience, DCA and its derivatives may prove to be useful in probing regulatory aspects of intermediary metabolism and in the acute or chronic treatment of several metabolic disorders.
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Affiliation(s)
- P W Stacpoole
- Department of Medicine, University of Florida, College of Medicine, Gainesville 32610
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Jacoby DB, Zilz ND, Towle HC. Sequences within the 5′-flanking region of the S14 gene confer responsiveness to glucose in primary hepatocytes. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84612-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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25
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Fabregat I, Lorenzo M, Benito M. Precocious induction of malic enzyme by nutritional and hormonal factors in rat foetal hepatocyte primary cultures. Biochem Biophys Res Commun 1989; 161:1028-34. [PMID: 2662970 DOI: 10.1016/0006-291x(89)91346-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Rat foetal hepatocytes in primary cultures were used as a model for the study of malic enzyme gene expression. Carbohydrates and glycolytic metabolites produced the precocious induction of the malic enzyme in foetal hepatocytes cultured in the absence of serum and hormones. Palmitate prevented this induction. Insulin and triiodothyronine produced a significant increase in the malic enzyme specific activity in all the conditions studied. A synergistic effect between the two hormones is observed only when high concentrations of glucose are present. Glucagon prevents partially the induction produced by insulin plus triiodothyronine. Both carbohydrate and hormonal inductions of malic enzyme activity are related to parallel increases in its expression, and are prevented by protein synthesis inhibitors.
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Affiliation(s)
- I Fabregat
- Departamento de Bioquímica y Biología Molecular, Ciudad Universitaria, Madrid, Spain
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26
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Kim MH, Nakayama R, Manos P, Tomlinson JE, Choi E, Ng JD, Holten D. Regulation of apolipoprotein E synthesis and mRNA by diet and hormones. J Lipid Res 1989. [DOI: 10.1016/s0022-2275(20)38323-1] [Citation(s) in RCA: 14] [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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27
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Grunnet N, Vind C, Dich J. Maintenance of alcohol dehydrogenase activity in long-term culture of hepatocytes from female rat. Alcohol Clin Exp Res 1989; 13:25-8. [PMID: 2646972 DOI: 10.1111/j.1530-0277.1989.tb00278.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Conditions for maintaining the activity of alcohol dehydrogenase in cultures of hepatocytes isolated from female rats were studied. The activity of alcohol dehydrogenase in freshly isolated cells was 1.7 U/mg DNA. When cultured, the activity declined 20% after one day of culture, irrespective of the culture conditions. In a conventional medium with 5 mM glucose the activity after one week of culture was only 30% of that initially measured in culture. Addition of 25 mM glucose or a high concentration of amino acids delayed the decrease. When these compounds were added together it was possible to maintain the initial activity for one week, but the activity declined during the following week. Addition of growth hormone had no effect during the first week of culture but abolished the fall during the second week. The initial metabolism of ethanol was 0.65 mumol/min x mg DNA and declined to two-thirds during the 2 weeks of culture.
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Affiliation(s)
- N Grunnet
- Department of Biochemistry A, Panum Institute, University of Copenhagen, Denmark
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28
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Salati LM, Adkins-Finke B, Clarke SD. Free fatty acid inhibition of the insulin induction of glucose-6-phosphate dehydrogenase in rat hepatocyte monolayers. Lipids 1988; 23:36-41. [PMID: 2895410 DOI: 10.1007/bf02535302] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rat hepatocytes in monolayer culture were utilized to determine if the decrease in glucose-6-phosphate dehydrogenase (G6PD) activity resulting from the ingestion of fat can be mimicked by the addition of fatty acids to a chemically, hormonally defined medium. G6PD activity in cultured hepatocytes was induced several-fold by insulin. Dexamethasone or T3 did not amplify the insulin induction of G6PD. Glucose alone increased G6PD activity in cultured hepatocytes from fasted donors by nearly 500%. Insulin in combination with glucose induced G6PD an additional two-fold. The increase in G6PD activity caused by glucose was greater in hepatocytes isolated from 72 hr-fasted rats as compared to fed donor rats. Such a response was reminiscent of the "overshoot" phenomenon in which G6PD activity is induced well above the normal level by fasting-refeeding rats a high glucose diet. Addition of linoleate to the medium resulted in a significant suppression of insulin's ability to induce G6PD, but linoleate had no effect on the induction of G6PD activity by glucose alone. A shift to the right in the insulin-response curve for the induction of G6PD also was detected for the induction of malic enzyme and acetyl-CoA carboxylase. Arachidonate (0.25 mM) was a significantly more effective inhibitor of the insulin action than linoleate was. Apparently rat hepatocytes in monolayer culture can be utilized as a model to investigate the molecular mechanism by which fatty acids inhibit the production of lipogenic enzymes. In part, this mechanism of fatty acid inhibition involves desensitization of hepatocytes to the lipogenic action of insulin.
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Affiliation(s)
- L M Salati
- Graduate Program in Nutrition, University of Minnesota, St. Paul 55108
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Kinlaw WB, Schwartz HL, Towle HC, Oppenheimer JH. Opposing effects of glucagon and triiodothyronine on the hepatic levels of messenger ribonucleic acid S14 and the dependence of such effects on circadian factors. J Clin Invest 1986; 78:1091-6. [PMID: 3760185 PMCID: PMC423768 DOI: 10.1172/jci112665] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We have studied the effect of glucagon on the expression of a triiodothyronine (T3) and carbohydrate-inducible mRNA sequence (mRNA-S14) in rat liver that undergoes a threefold diurnal variation (peak, 2200 h; nadir, 0800 h). Glucagon injection into euthyroid rats (25 micrograms/100 g body wt i.p., three doses at 15-min intervals) during the nocturnal plateau of mRNA-S14 caused a monoexponential disappearance of this sequence (t1/2, 90 min) accompanied by a 90% reduction in the transcriptional rate in a nuclear run-off assay, indicative of a near total reduction of synthesis. This effect was markedly attenuated in rats treated with T3 (200 micrograms/100 g body wt i.p.) 24 h before glucagon injection. When T3 was given 15 min after glucagon, the glucagon-initiated decline in mRNA-S14 was reversed within 90 min, suggesting a rapid interaction between the two hormones in the evening. Curiously, administration of T3 alone at this hour did not affect a significant increase in mRNA-S14. At 0800 h, however, T3 caused the expected brisk induction of this sequence, whereas glucagon was without effect. In essence, glucagon affected mRNA-S14 synthesis only in the evening, while T3 increased levels of this sequence above the baseline only in the morning. T3, however, reversed the effect of prior glucagon injection at night. The observed alterations in hormonal responsivity could underly the diurnal variation of mRNA-S14 expression. Moreover, the data suggest the hypothesis that T3 may act on S14 gene expression by antagonizing factors that inhibit its transcription.
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Mariash CN, Seelig S, Schwartz HL, Oppenheimer JH. Rapid synergistic interaction between thyroid hormone and carbohydrate on mRNAS14 induction. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67552-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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31
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Abstract
We have previously suggested that the ability of glucose to induce rat hepatic lipogenic enzymes is mediated by the mitochondrial oxidation of pyruvate. In part, this hypothesis is supported by the finding that an activator of pyruvate dehydrogenase, dichloroacetic acid (DCA), is capable of inducing malic enzyme in hepatocyte cultures. In order to further test this hypothesis, we compared the mRNA responses induced by carbohydrate feeding in vivo and by glucose administration to hepatocytes in culture with those mRNA responses induced in DCA both in vivo and in culture. DCA administration to rats resulted in a significant increase in liver:body weight ratio. It was, in addition, a potent inducer of malic enzyme. Hepatic mRNA activity profiles were examined by two-dimensional gel electrophoretic analysis of in vitro translation products. Six of the seven mRNAs altered by carbohydrate feeding were similarly altered by DCA feeding in vivo. In cultured hepatocytes 10 mmol/L DCA significantly increased four of six glucose-induced mRNAs. The mRNA for malic enzyme was among those mRNA sequences induced both in vivo and in culture. Increasing glucose concentrations in the culture medium resulted in an expected rise in pyruvate levels, whereas DCA caused a significant decrease in the concentration of this intermediate. It is likely, therefore, that augmentation of the flux of pyruvate through pyruvate dehydrogenase rather than alterations in pyruvate levels per se, is a proximal event leading to the induction of multiple mRNAs. The marked overlap in mRNA response to both carbohydrate and DCA indicates that the signal regulating the content of the carbohydrate responsive mRNAs is derived from mitochondrial pyruvate oxidation.
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Abstract
The interaction between thyroid hormone (T3) and nutritional signals has been of interest for nearly a century. Thus, enhanced glucose production, absorption and utilization are associated with hyperthyroidism, whereas diminished glucose utilization and lipogenesis characterize hypothyroidism. Recent studies have uncovered what appears to be yet another area of interaction at the molecular level. On the one hand, a marked overlap exists between the changes in rat hepatic mRNA activity profile induced by hyperthyroidism and high carbohydrate administration. On the other hand, the patterns produced by hypothyroidism, starvation and diabetes are characterized by oppositely directed shifts. These findings may be due, in part, to a synergistic relationship between carbohydrate feeding and T3 administration in the induction of many hepatic lipogenic enzymes and their respective mRNAs. Studies both in the intact rat as well as in isolated hepatocyte cultures indicate that this synergism arises from the ability of T3 to multiply an intracellular signal derived from the metabolism of glucose. The development of recombinant DNA techniques can now be applied to the study of the interaction of T3 with nutritional signals. Initial efforts have demonstrated a hepatic mRNA (mRNAS14) rapidly responsive to both T3 and carbohydrates. With this probe, studies are under way to define the precise molecular mechanisms by which T3 and carbohydrates interact to influence gene expression.
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Mariash CN, Jump DB, Oppenheimer JH. T3 stimulates the synthesis of a specific mRNA in primary hepatocyte culture. Biochem Biophys Res Commun 1984; 123:1122-9. [PMID: 6548379 DOI: 10.1016/s0006-291x(84)80249-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The mechanism of triiodothyronine (T3) induction of a thyroid hormone responsive mRNA (mRNAS14) was studied in primary cultures of adult rat hepatocytes. T3 induced mRNAS14 in less than one hour after addition to the cultures. After 24 hours exposure to T3, the level of mRNAS14 was 2.5 to 6 times above the untreated controls. Addition of Actinomycin-D to both induced and control cultures led to similar mRNAS14 disappearance curves, implying that T3 augments the synthesis of mRNAS14 rather than stabilizing pre-formed mature mRNA. Glucagon inhibits the T3 induction of mRNAS14. When added to both induced and control cultures, glucagon leads to similar fractional decay curves for mRNAS14, confirming the Actinomycin-D studies. These findings demonstrate T3 induces mRNAS14 directly in the hepatocyte by increasing the synthesis of the mature mRNA.
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