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Fernandes GW, Bocco BMLC. Hepatic Mediators of Lipid Metabolism and Ketogenesis: Focus on Fatty Liver and Diabetes. Curr Diabetes Rev 2021; 17:e110320187539. [PMID: 33143628 DOI: 10.2174/1573399816999201103141216] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 09/29/2020] [Accepted: 10/03/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Diabetes mellitus (DM) is a chronic disorder that it is caused by the absence of insulin secretion due to the inability of the pancreas to produce it (type 1 diabetes; T1DM), or due to defects of insulin signaling in the peripheral tissues, resulting in insulin resistance (type 2 diabetes; T2DM). Commonly, the occurrence of insulin resistance in T2DM patients reflects the high prevalence of obesity and non-alcoholic fatty liver disease (NAFLD) in these individuals. In fact, approximately 60% of T2DM patients are also diagnosed to have NAFLD, and this condition is strongly linked with insulin resistance and obesity. NAFLD is the hepatic manifestation of obesity and metabolic syndrome and includes a spectrum of pathological conditions, which range from simple steatosis (NAFL), non-alcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma. NAFLD manifestation is followed by a series of hepatic lipid deregulations and the main abnormalities are increased triglyceride levels, increased hepatic production of VLDL and a reduction in VLDL catabolism. During the progression of NAFLD, the production of ketone bodies progressively reduces while hepatic glucose synthesis and output increases. In fact, most of the fat that enters the liver can be disposed of through ketogenesis, preventing the development of NAFLD and hyperglycemia. OBJECTIVE This review will focus on the pathophysiological aspect of hepatic lipid metabolism deregulation, ketogenesis, and its relevance in the progression of NAFLD and T2DM. CONCLUSION A better understanding of the molecular mediators involved in lipid synthesis and ketogenesis can lead to new treatments for metabolic disorders in the liver, such as NAFLD.
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Affiliation(s)
- Gustavo W Fernandes
- Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago IL, United States
| | - Barbara M L C Bocco
- Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago IL, United States
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DiStefano JK. Fructose-mediated effects on gene expression and epigenetic mechanisms associated with NAFLD pathogenesis. Cell Mol Life Sci 2020; 77:2079-2090. [PMID: 31760464 PMCID: PMC7440926 DOI: 10.1007/s00018-019-03390-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a chronic, frequently progressive condition that develops in response to excessive hepatocyte fat accumulation (i.e., steatosis) in the absence of significant alcohol consumption. Liver steatosis develops as a result of imbalanced lipid metabolism, driven largely by increased rates of de novo lipogenesis and hepatic fatty acid uptake and reduced fatty acid oxidation and/or disposal to the circulation. Fructose is a naturally occurring simple sugar, which is most commonly consumed in modern diets in the form of sucrose, a disaccharide comprised of one molecule of fructose covalently bonded with one molecule of glucose. A number of observational and experimental studies have demonstrated detrimental effects of dietary fructose consumption not only on diverse metabolic outcomes such as insulin resistance and obesity, but also on hepatic steatosis and NAFLD-related fibrosis. Despite the compelling evidence that excessive fructose consumption is associated with the presence of NAFLD and may even promote the development and progression of NAFLD to more clinically severe phenotypes, the molecular mechanisms by which fructose elicits effects on dysregulated liver metabolism remain unclear. Emerging data suggest that dietary fructose may directly alter the expression of genes involved in lipid metabolism, including those that increase hepatic fat accumulation or reduce hepatic fat removal. The aim of this review is to summarize the current research supporting a role for dietary fructose intake in the modulation of transcriptomic and epigenetic mechanisms underlying the pathogenesis of NAFLD.
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Affiliation(s)
- Johanna K DiStefano
- Diabetes and Fibrotic Disease Unit, Translational Genomics Research Institute, 445 N 5th Street, Phoenix, AZ, 85004, USA.
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Hein GJ, Chicco A, Lombardo YB. Fish oil normalizes plasma glucose levels and improves liver carbohydrate metabolism in rats fed a sucrose-rich diet. Lipids 2011; 47:141-50. [PMID: 22045300 DOI: 10.1007/s11745-011-3623-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 10/04/2011] [Indexed: 12/23/2022]
Abstract
A sucrose-rich diet (SRD) induces insulin resistance and dyslipidemia with impaired hepatic glucose production and gluconeogenesis, accompanied by altered post-receptor insulin signaling steps. The aim of this study was to examine the effectiveness of fish oil (FO) to reverse or improve the impaired hepatic glucose metabolism once installed in rats fed 8 months a SRD. In the liver of rats fed SRD in which FO replaced corn-oil during the last 2 months, as dietary fat, several key enzyme activities and metabolites involved in glucose metabolisms (phosphorylation, glycolysis, gluconeogenesis and oxidative and non oxidative glucose pathway) were measured. The protein mass levels of IRS-1 and αp85 PI-3K at basal conditions were also analyzed. FO improved the altered activities of some enzymes involved in the glycolytic and oxidative pathways observed in the liver of SRD fed rats but was unable to restore the impaired capacity of glucose phosphorylation. Moreover, FO reversed the increase in PEPCK and G-6-Pase and reduced the G-6-Pase/GK ratio. Glycogen concentration and GSa activity returned to levels similar to those observed in the liver of the control-fed rats. Besides, FO did not modify the altered protein mass levels of IRS-1 and αp85 PI-3K. Finally, dietary FO was effective in reversing or improving the impaired activities of several key enzymes of hepatic carbohydrate metabolism contributing, at least in part, to the normalization of plasma glucose levels in the SRD-fed rats. However, these positive effects of FO were not observed under basal conditions in the early steps of insulin signaling transduction.
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Affiliation(s)
- Gustavo J Hein
- Department of Biochemistry, School of Biochemistry, University of Litoral, Ciudad Universitaria Paraje El Pozo. CC 242 (3000), Santa Fe, Argentina
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Suzuki T, Kawamoto M, Murai A, Muramatsu T. Identification of the regulatory region of the L-type pyruvate kinase gene in mouse liver by hydrodynamics-based gene transfection. J Nutr 2006; 136:16-20. [PMID: 16365052 DOI: 10.1093/jn/136.1.16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Expression of L-type pyruvate kinase (L-PK) is upregulated in the liver by dietary carbohydrate. Previously, 3 carbohydrate/insulin response elements were identified in the 5'-flanking region of the L-PK gene up to bp -170. Studies of the 5'-flanking region beyond bp -183 in transgenic mice suggested that other regulatory elements may be present upstream of bp -183, but the positions of these elements were uncertain. In the present study, the existence of regulatory regions of the L-PK gene responding to stimulation by feeding was examined using in vivo hydrodynamics-based gene transfection (HT) in mouse liver. The firefly-luciferase (FL) gene, fused with various lengths of the 5'-flanking region of the L-PK gene, was introduced into mouse liver by HT. The mice had free access to a high-carbohydrate diet. In liver homogenate, luciferase activity of pL-PK(-1467)-FL (which included the 5'-flanking region from bp -1467 to +17), was markedly stimulated by feeding. 5'-Deletion up to bp -1065 caused only minor changes in luciferase activity, but further deletion up to bp -690 and bp -203 caused significant, gradual decreases in activity. Further analyses utilizing 5'-deletion mutants indicated the existence of positive regulatory regions that respond to stimulation by feeding between bp -1065 and -945, and between -300 and -203 on the L-PK gene. These results suggest that unidentified cis-acting DNA elements exist in the upstream region of the L-PK gene, and that HT is a useful approach for detecting regulatory regions of genes expressed in the liver.
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Affiliation(s)
- Takayuki Suzuki
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
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Asai Y, Yamada K, Watanabe T, Keng VW, Noguchi T. Insulin stimulates expression of the pyruvate kinase M gene in 3T3-L1 adipocytes. Biosci Biotechnol Biochem 2003; 67:1272-7. [PMID: 12843653 DOI: 10.1271/bbb.67.1272] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
M2-type pyruvate kinase (M2-PK) mRNA is produced from the PKM gene by an alternative RNA splicing in adipocytes. We found that insulin increased the level of M2-PK mRNA in 3T3-L1 adipocytes in both time- and dose-dependent manners. This induction did not require the presence of glucose or glucosamine in the medium. The insulin effect was blocked by pharmacological inhibitors of insulin signaling pathways such as wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K), and PD98059, an inhibitor of mitogen-activated protein kinase (MAPK) kinase. A stable reporter expression assay showed that the promoter activity of an about 2.2-kb 5'-flanking region of the rat PKM gene was stimulated by insulin, but the extents of these stimulations were lower than those of the mRNA stimulation. Thus, we suggest that insulin increases the level of M2-PK mRNA in adipocytes by acting at transcriptional and post-transcriptional levels through signaling pathways involving both PI3K and MAPK kinase.
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Affiliation(s)
- Yuuki Asai
- Department of Applied Molecular Biosciences, Nagoya University Graduate School of Bioagricultural Sciences, Chikusa.ku, Nagoya 464-8601, Japan
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Girard J, Ferré P, Foufelle F. Mechanisms by which carbohydrates regulate expression of genes for glycolytic and lipogenic enzymes. Annu Rev Nutr 1997; 17:325-52. [PMID: 9240931 DOI: 10.1146/annurev.nutr.17.1.325] [Citation(s) in RCA: 254] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Regulation of gene expression by nutrients is an important mechanism in the adaptation of mammals to their nutritional environment. This is especially true for enzymes involved in the storage of energy, such as the lipogenic and glycolytic enzymes in liver and adipose tissue. Transcription of the genes for lipogenic and glycolytic enzymes is stimulated by glucose in adipose tissue, liver, and pancreatic beta-cells. Several lines of evidence suggest that glucose must be metabolized to glucose-6-phosphate to stimulate gene transcription. In adipose tissue, insulin increases the expression of lipogenic enzymes indirectly by stimulating glucose uptake. In the liver, insulin also acts indirectly by stimulating the expression of glucokinase and, hence, by increasing glucose metabolism. Glucose response elements have been characterized for the L-pyruvate kinase and S14 genes. They have in common the presence of a sequence 5'-CACGTG-3', which binds a transcription factor called USF (upstream stimulatory factor). Another glucose response element, which uses a transcription factor named Sp1, has been characterized in the gene for the acetyl-coenzyme A carboxylase. The mechanisms linking glucose-6-phosphate to the glucose-responsive transcription complex are largely unknown.
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Affiliation(s)
- J Girard
- Centre de Recherches sur l'Endocrinologie Moléculaire et le Dévelopement, UPR 1511 CNRS, Meudon, France
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Foufelle F, Girard J, Ferré P. Regulation of lipogenic enzyme expression by glucose in liver and adipose tissue: a review of the potential cellular and molecular mechanisms. ADVANCES IN ENZYME REGULATION 1996; 36:199-226. [PMID: 8869748 DOI: 10.1016/0065-2571(95)00010-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Regulation of gene expression by nutrients is an important part of the mechanisms allowing mammals to adapt to their nutritional environment. This is especially true for enzymes involved in the storage of energy such as the lipogenic and glycolytic enzymes in the liver and adipose tissue. We review in the present paper the cellular and molecular mechanisms involved in the regulation of glycolytic and lipogenic enzyme gene expression by glucose. In vivo and in vitro experiments have demonstrated that FAS and ACC gene expression is upregulated by glucose in adipose tissue, FAS, ACC and L-PK expression in the liver and ACC and L-PK expression in a pancreatic beta-cell line. This regulation involves the stimulation of their transcription. In order for glucose to act as a gene inducer, it must be metabolized. In adipose tissue, insulin increases indirectly the expression of FAS and ACC by stimulating glucose metabolism through its well-known effect on glucose transport. In the liver, the action of insulin is also indirect by allowing the expression of glucokinase and hence by increasing glucose metabolism. In the liver, fructose has a potentiating effect on the stimulation of gene expression by glucose through its stimulatory effect on glucokinase activity. Several evidences suggest that glucose-6-phosphate is the signal metabolite: (i) the effect of glucose is mimicked by 2-deoxyglucose (a glucose analogue whose metabolism stops after its phosphorylation by hexokinase) in adipose tissue and beta-cell line but not in the liver in which 2-deoxyglucose-6-phosphate does not accumulate, (ii) intracellular glucose-6-phosphate concentration varies in parallel with ACC, FAS and L-PK mRNA concentrations in liver, adipose tissue and beta-cell line, (iii) in vivo, the kinetics of hexose-phosphate fits with the time-related pattern of gene induction. Glucose response elements have been characterized on three genes, L-PK, S14 (a gene which codes for a protein of unknown function but which is directly related to lipogenesis) and FAS. These glucose response elements have all in common the presence of a sequence 5'-CACGTG-3' which binds a transcription factor of the basic domain, helix-loop-helix, leucine zipper family called USF/MLTF, although the organization of the overall glucose response element probably differs from one gene to another. The mechanisms linking glucose-6-phosphate to the glucose responsive transcription complex are presently largely unknown.
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Affiliation(s)
- F Foufelle
- Unité INSERM 342, Hôpital Saint-Vincent-de-Paul, Paris, France
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Blakeley S, Gottlob-McHugh S, Wan J, Crews L, Miki B, Ko K, Dennis DT. Molecular characterization of plastid pyruvate kinase from castor and tobacco. PLANT MOLECULAR BIOLOGY 1995; 27:79-89. [PMID: 7865798 DOI: 10.1007/bf00019180] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Clones encoding two different forms of plastid pyruvate kinase (PKp; EC 2.7.1.40) have been isolated from both castor and tobacco seed cDNA libraries. One form, designated PKpA, from castor was described in a previous report, and the tobacco homologue of PKpA has now been isolated. In addition, a second cDNA, designated PKpG, has been identified and sequenced in both species. Western blot analysis, using antibodies raised against protein overexpressed from these clones, indicates that they encode the two predominant polypeptides of plastid pyruvate kinase from developing castor endosperm. In castor, both PKpA and PKpG are encoded by single genes. In the allotetraploid Nicotiana tabacum, there are two copies of each, one derived from each of the progenitors of this species. The expression of the genes for PKpA and PKpG was examined in various tissues from both castor and tobacco. In castor, both forms are expressed in developing and germinating endosperm and in the root but neither is expressed in the leaf. In tobacco, both forms are expressed in developing seeds but in mature tissues, PKpA is most abundant in roots and PKpG in leaves.
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Affiliation(s)
- S Blakeley
- Department of Biology, Queens University, Kingston, Ontario, Canada
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Insulin and dietary fructose induce stearoyl-CoA desaturase 1 gene expression of diabetic mice. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)47053-6] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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11
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Doiron B, Cuif M, Kahn A, Diaz-Guerra M. Respective roles of glucose, fructose, and insulin in the regulation of the liver-specific pyruvate kinase gene promoter. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)34047-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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12
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Noguchi T, Matsuda T, Tomari Y, Yamada K, Imai E, Wang Z, Ikeda H, Tanaka T. The regulation of gene expression by insulin is differentially impaired in the liver of the genetically obese-hyperglycemic Wistar fatty rat. FEBS Lett 1993; 328:145-8. [PMID: 7688320 DOI: 10.1016/0014-5793(93)80982-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The regulation by insulin and carbohydrates of the gene expression of three key enzymes involved in glucose metabolism was studied in the liver of the Wistar fatty rat, a model of obese non-insulin-dependent diabetes mellitus. A high glucose or fructose diet, or insulin administration caused a similar magnitude of increase in the level of L-type pyruvate kinase mRNA in the liver of Wistar fatty rats and their lean littermates. However, the induction of glucokinase mRNA and repression of phosphoenolpyruvate carboxykinase mRNA by dietary glucose or insulin were impaired in the fatty rats, whereas fructose caused a similar decrease in phosphoenolpyruvate carboxykinase mRNA in both types of rats. These results indicate that the regulation of gene expression of glucokinase and phosphoenolpyruvate carboxykinase, but not of L-type pyruvate kinase, by insulin is impaired in the liver of the Wistar fatty rat.
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Affiliation(s)
- T Noguchi
- Department of Nutrition and Physiological Chemistry, Osaka University Medical School, Japan
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Noguchi T, Okabe M, Wang Z, Yamada K, Imai E, Tanaka T. An enhancer unit of L-type pyruvate kinase gene is responsible for transcriptional stimulation by dietary fructose as well as glucose in transgenic mice. FEBS Lett 1993; 318:269-72. [PMID: 8440382 DOI: 10.1016/0014-5793(93)80526-z] [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: 01/30/2023]
Abstract
We produced three lines of transgenic mice containing the 5' flanking region of the L-type pyruvate kinase gene from nucleotides -189 to +37, which includes an enhancer unit and TATA box as functional elements, linked to the chloramphenicol acetyltransferase gene. Since transgene expression was stimulated by both dietary fructose and glucose in a tissue-dependent manner, we suggest that this unit is responsive to both stimuli.
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Affiliation(s)
- T Noguchi
- Department of Nutrition and Physiological Chemistry, Osaka University Medical School, Japan
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Antoine B, Levrat F, Vallet V, Berbar T, Cartier N, Dubois N, Briand P, Kahn A. Gene expression in hepatocyte-like lines established by targeted carcinogenesis in transgenic mice. Exp Cell Res 1992; 200:175-85. [PMID: 1373387 DOI: 10.1016/s0014-4827(05)80086-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
New hepatocyte-like cell lines (mhAT) were derived from the liver of a transgenic mouse expressing SV40 early genes under the direction of the liver-specific antithrombin III gene promoter (ATIII-TSV40). Their differentiated phenotypes were improved and stabilized by the use of liver-specific growth media (arginine-free, glucose-free, or low-fructose/glucose-free medium). The best differentiated lines display a very high level of albumin, transferrin, and L-type pyruvate kinase (L-PK) gene expression that is comparable to that observed in the mouse liver. Abundance of the aldolase B and phosphoenolpyruvate carboxykinase (PEPCK) transcripts varied from 5 to 35% of the in vivo concentrations while abundance of the alpha-fetoprotein and phenylalanine hydroxylase transcripts remained very low. Hormonal (cAMP and insulin) and nutritional (glucose) gene controls of PEPCK and L-PK were, at least partially, conserved. mhAT cells are readily transfectable by the calcium phosphate coprecipitation technique and exhibit a liver-specific pattern of expression of exogenous genes. Thus, mhAT cells seem suitable for the analysis of the regulatory regions involved in the tissue-specific transcription of genes. This work demonstrates, therefore, the great efficiency of targeted carcinogenesis in transgenic mice to create new differentiated cell lines. The availability of various lines of liver-specific cells with different phenotypes will constitute useful tools to establish correlations between expression of trans-acting factors and control of the phenotype.
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Affiliation(s)
- B Antoine
- Institut Cochin de Génétique Moléculaire, laboratoire de recherche en génétique et pathologie moléculaires (INSERM U129), Paris, France
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Iritani N. Nutritional and hormonal regulation of lipogenic-enzyme gene expression in rat liver. ACTA ACUST UNITED AC 1992; 205:433-42. [PMID: 1349281 DOI: 10.1111/j.1432-1033.1992.tb16797.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- N Iritani
- Tezukayama Gakuin College, Osaka, Japan
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Yamada K, Noguchi T, Miyazaki J, Matsuda T, Takenaka M, Yamamura K, Tanaka T. Tissue-specific expression of rat pyruvate kinase L/chloramphenicol acetyltransferase fusion gene in transgenic mice and its regulation by diet and insulin. Biochem Biophys Res Commun 1990; 171:243-9. [PMID: 2203346 DOI: 10.1016/0006-291x(90)91383-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We produced transgenic mice carrying about 3 kb of the 5'-flanking sequence of the rat pyruvate kinase L gene linked to the chloramphenicol acetyltransferase (CAT) structural gene. Expression of the transgene was observed only in tissues in which the endogenous L-type pyruvate kinase is expressed. Dietary glucose or insulin induced similar increases in the levels of CAT and L-type pyruvate kinase mRNAs in the liver. However, the fructose-induced level of CAT mRNA was about 3- and 6- fold lower than those of endogenous L-type pyruvate kinase mRNA in the liver and kidney, respectively, confirming our previous finding that stabilization of the transcripts of the pyruvate kinase L gene is an important regulatory step in fructose induction, especially in the kidney. Thus we conclude that all the cis-acting elements responsible for tissue-specific expression of the L-type pyruvate kinase and its stimulation by dietary components and insulin are localized in the sequence from about nucleotide -3000 to +37 in the pyruvate kinase L gene.
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Affiliation(s)
- K Yamada
- Department of Nutrition and Physiological Chemistry, Osaka University Medical School, Japan
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Kim MH, Nakayama R, Holten D. Quantitation of glucose-6-phosphate dehydrogenase mRNA by solution hybridization: correlation with rates of synthesis. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1049:177-81. [PMID: 2163684 DOI: 10.1016/0167-4781(90)90038-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Rat liver glucose-6-phosphate dehydrogenase (G6PD) is one of several proteins involved in lipid metabolism whose synthesis is regulated by diet. In experiments reported here, rats were fasted or fed diets until a new steady state level of G6PD was produced. Livers were used to measure G6PD activity, synthesis and mRNA simultaneously. Since accurate quantitation of G6PD mRNA by Northern blots was found to be difficult in noninduced animals a new solution hybridization assay was also used. Noninduced rats have approx. One molecule of G6PD mRNA per liver cell. Changes in G6PD mRNA are larger than previously reported and, at the steady state, can completely account for the 33-fold change in G6PD activity and synthesis when fasted rats are refed a high carbohydrate diet. In contrast, a high fat carbohydrate-free diet does not increase G6PD mRNA and dibutyryl cAMP lowers G6PD mRNA. Since changes in G6PD synthesis and activity are closely correlated, degradation of G6PD is not significantly regulated.
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Affiliation(s)
- M H Kim
- Department of Biochemistry, University of California, Riverside 92521-0129
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Hamblin PS, Ozawa Y, Jefferds A, Mariash CN. Interaction Between Fructose and Glucose on the Regulation of the Nuclear Precursor for mRNA-S14. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(20)88234-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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19
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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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20
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Regulation of the expression of the L-type pyruvate kinase gene in adult rat hepatocytes in primary culture. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)80103-x] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Dillmann WH. Diabetes mellitus-induced changes in the concentration of specific mRNAs and proteins. DIABETES/METABOLISM REVIEWS 1988; 4:789-97. [PMID: 3069403 DOI: 10.1002/dmr.5610040807] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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