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Rahimi L, Rajpal A, Ismail-Beigi F. Glucocorticoid-Induced Fatty Liver Disease. Diabetes Metab Syndr Obes 2020; 13:1133-1145. [PMID: 32368109 PMCID: PMC7171875 DOI: 10.2147/dmso.s247379] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/27/2020] [Indexed: 01/08/2023] Open
Abstract
Glucocorticoids (GCs) are commonly used at high doses and for prolonged periods (weeks to months) in the treatment of a variety of diseases. Among the many side effects are increased insulin resistance with disturbances in glucose/insulin homeostasis and increased deposition of lipids (mostly triglycerides) in the liver. Here, we review the metabolic pathways of lipid deposition and removal from the liver that become altered by excess glucocorticoids. Pathways of lipid deposition stimulated by excess glucocorticoids include 1) increase in appetite and high caloric intake; 2) increased blood glucose levels due to GC-induced stimulation of gluconeogenesis; 3) stimulation of de novo lipogenesis that is augmented by the high glucose and insulin levels and by GC itself; and 4) increased release of free fatty acids from adipose stores and stimulation of their uptake by the liver. Pathways that decrease hepatic lipids affected by glucocorticoids include a modest stimulation of very-low-density lipoprotein synthesis and secretion into the circulation and inhibition of β-oxidation of fatty acids. Role of 11β-hydroxysteroid dehydrogenases-1 and -2 and the reversible conversion of cortisol to cortisone on intracellular levels of cortisol is examined. In addition, GC control of osteocalcin expression and the effect of this bone-derived hormone in increasing insulin sensitivity are discussed. Finally, research focused on gaining a better understanding of the dose and duration of treatment with glucocorticoids, which leads to increased triglyceride deposition in the liver, and the reversibility of the condition is highlighted.
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Affiliation(s)
- Leili Rahimi
- Department of Medicine, Case Western Reserve University, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
| | - Aman Rajpal
- Department of Medicine, Case Western Reserve University, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
- Cleveland VA Medical Center, Cleveland, OH, USA
| | - Faramarz Ismail-Beigi
- Department of Medicine, Case Western Reserve University, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
- Cleveland VA Medical Center, Cleveland, OH, USA
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Tang H, Wu Y, Qin Y, Wang H, Jia Y, Yang S, Luo S, Wang Q. Predictive significance of HMGCS2 for prognosis in resected Chinese esophageal squamous cell carcinoma patients. Onco Targets Ther 2017; 10:2553-2560. [PMID: 28546759 PMCID: PMC5438074 DOI: 10.2147/ott.s132543] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Despite a series of attempts during the last decades, the prognosis of esophageal squamous cell carcinoma (ESCC) remains poor. Different responses of individual tumors encouraged us to look for valuable prognostic markers. As a key regulator controlling the anabolic ketogenic pathway, 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) has been reported to play a crucial role in colorectal cancer and prostate cancer. However, its importance to ESCC has not been verified. Therefore, a large cohort retrospective study was planned, to investigate the relationship between HMGCS2 expression and ESCC prognosis. By adopting real-time polymerase chain reaction (PCR) and immunohistochemical (IHC) staining, HMGCS2 expression was examined in tissues of 300 ESCC patients with complete resection. Besides, the association between HMGCS2 protein expression and survival time was evaluated through chi-square test and Kaplan–Meier analysis. With the use of Cox-proportional hazards model, the prognostic impact of clinicopathologic variables and biomarker expression was evaluated. Compared with their non-tumor counterparts, HMGCS2 downregulation occurred in 65.5% and 37.6% of primary ESCCs on the mRNA and protein levels (P<0.001), respectively. On the protein level, HMGCS2 expression was associated with tumor cell differentiation (P=0.003), pT status (P=0.006), and TNM stage (P=0.010). In the down-HMGCS2 expression group, the 5-year overall survival (OS) and relapse-free survival (RFS) are poorer than those in the normal expression group (19 months vs 24 months, P=0.002; 13 months vs 17 months, P=0.007, respectively). According to the TNM stage, stratified analysis revealed that its discernibility on RFS was only pronounced in patients with advanced clinical stage (P=0.001). In addition, multivariate Cox regression analysis showed that HMGCS2 expression was an independent risk factor for RFS (P=0.032) instead of OS (P=0.099). The findings of this study provided the evidence that HMGSC2 represented a potential novel prognostic biomarker for ESCC patients.
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Affiliation(s)
- Hong Tang
- Department of Internal Medicine, Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital
| | - Yufeng Wu
- Department of Internal Medicine, Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital
| | - Yanru Qin
- Department of Clinical Oncology, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan, China
| | - Hongyan Wang
- Department of Internal Medicine, Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital
| | - Yongxu Jia
- Department of Clinical Oncology, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan, China
| | - Shujun Yang
- Department of Internal Medicine, Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital
| | - Suxia Luo
- Department of Internal Medicine, Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital
| | - Qiming Wang
- Department of Internal Medicine, Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital
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3
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Screening of Chicken Genes Related to Germ Cell Development. JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2007. [DOI: 10.5187/jast.2007.49.2.183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Camarero N, Mascaró C, Mayordomo C, Vilardell F, Haro D, Marrero PF. KetogenicHMGCS2Is a c-Myc Target Gene Expressed in Differentiated Cells of Human Colonic Epithelium and Down-Regulated in Colon Cancer. Mol Cancer Res 2006; 4:645-53. [PMID: 16940161 DOI: 10.1158/1541-7786.mcr-05-0267] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
HMGCS2, the gene that regulates ketone body production, is expressed in liver and several extrahepatic tissues, such as the colon. In CaCo-2 colonic epithelial cells, the expression of this gene increases with cell differentiation. Accordingly, immunohistochemistry with specific antibodies shows that HMGCS2 is expressed mainly in differentiated cells of human colonic epithelium. Here, we used a chromatin immunoprecipitation assay to study the molecular mechanism responsible for this expression pattern. The assay revealed that HMGCS2 is a direct target of c-Myc, which represses HMGCS2 transcriptional activity. c-Myc transrepression is mediated by blockade of the transactivating activity of Miz-1, which occurs mainly through a Sp1-binding site in the proximal promoter of the gene. Accordingly, the expression of human HMGCS2 is down-regulated in 90% of Myc-dependent colon and rectum tumors. HMGCS2 protein expression is down-regulated preferentially in moderately and poorly differentiated carcinomas. In addition, it is also down-regulated in 80% of small intestine Myc-independent tumors. Based on these findings, we propose that ketogenesis is an undesirable metabolic characteristic of the proliferating cell, which is down-regulated through c-Myc-mediated repression of the key metabolic gene HMGCS2.
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Affiliation(s)
- Nuria Camarero
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Barcelona, E-08028 Barcelona, Spain
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5
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Sato T, Yamamoto H, Sawada N, Nashiki K, Tsuji M, Muto K, Kume H, Sasaki H, Arai H, Nikawa T, Taketani Y, Takeda E. Restraint stress alters the duodenal expression of genes important for lipid metabolism in rat. Toxicology 2006; 227:248-61. [PMID: 16962226 DOI: 10.1016/j.tox.2006.08.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2006] [Revised: 08/09/2006] [Accepted: 08/09/2006] [Indexed: 10/24/2022]
Abstract
Stress, such as trauma and injury, is known to cause transcriptional changes in various tissues; however, there is little information on tissue-specific gene expression in response to stress. Here, we have examined duodenal gene expression in rats subjected to whole-body immobilization in order to elucidate the mechanism underlying the stress response in the duodenum--one of the tissues that is most sensitive to external stress. DNA microarray analysis revealed that the immobilization for 2 weeks caused great changes in gene expression in the rat duodenum: 165 genes exhibited more than a two-fold change in expression level (103 up-regulated; 62 down-regulated). In addition, functional classification of these genes showed that immobilization preferentially stimulated the expression of genes related to lipid metabolism, including genes encoding mitochondrial HMG-CoA synthase, a key enzyme in ketogenesis; solute carrier 27A2, a fatty acid transporter; and dienoyl CoA reductase, a key enzyme in beta-oxidation. To elucidate the factors mediating these immobilization-induced changes, we treated rats and small intestinal IEC-6 cells with dexamethasone and hydrogen peroxide. In both rats and IEC-6 cells, treatment with dexamethasone induced changes in gene expression that mimicked the immobilization-mediated increase in expression of the mitochondrial HMG-CoA synthase and dienoyl CoA reductase transcripts, suggesting that stress-induced synthesis of glucocorticoid hormones mediates, at least in part, the stress response in the duodenum. These results suggest that immobilization may alter lipid metabolism in the small intestine by modifying the expression of specific genes through which the small intestine may seek to protect itself from stress-induced damage.
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Affiliation(s)
- Tadatoshi Sato
- Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15, Kuramoto-cho, Tokushima 770-8503, Japan.
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6
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Steussy CN, Vartia AA, Burgner JW, Sutherlin A, Rodwell VW, Stauffacher CV. X-ray crystal structures of HMG-CoA synthase from Enterococcus faecalis and a complex with its second substrate/inhibitor acetoacetyl-CoA. Biochemistry 2006; 44:14256-67. [PMID: 16245942 DOI: 10.1021/bi051487x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biosynthesis of the isoprenoid precursor, isopentenyl diphosphate, is a critical function in all independently living organisms. There are two major pathways for this synthesis, the non-mevalonate pathway found in most eubacteria and the mevalonate pathway found in animal cells and a number of pathogenic bacteria. An early step in this pathway is the condensation of acetyl-CoA and acetoacetyl-CoA into HMG-CoA, catalyzed by the enzyme HMG-CoA synthase. To explore the possibility of a small molecule inhibitor of the enzyme functioning as a non-cell wall antibiotic, the structure of HMG-CoA synthase from Enterococcus faecalis (MVAS) was determined by selenomethionine MAD phasing to 2.4 A and the enzyme complexed with its second substrate, acetoacetyl-CoA, to 1.9 A. These structures show that HMG-CoA synthase from Enterococcus is a member of the family of thiolase fold enzymes and, while similar to the recently published HMG-CoA synthase structures from Staphylococcus aureus, exhibit significant differences in the structure of the C-terminal domain. The acetoacetyl-CoA binary structure demonstrates reduced coenzyme A and acetoacetate covalently bound to the active site cysteine through a thioester bond. This is consistent with the kinetics of the reaction that have shown acetoacetyl-CoA to be a potent inhibitor of the overall reaction, and provides a starting point in the search for a small molecule inhibitor.
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Affiliation(s)
- C Nicklaus Steussy
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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7
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Camarero N, Nadal A, Barrero MJ, Haro D, Marrero PF. Histone deacetylase inhibitors stimulate mitochondrial HMG-CoA synthase gene expression via a promoter proximal Sp1 site. Nucleic Acids Res 2003; 31:1693-703. [PMID: 12626711 PMCID: PMC152864 DOI: 10.1093/nar/gkg262] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The expression of mitochondrial HMG-CoA synthase in the colon has been correlated with the levels of butyrate present in this tissue. We report here that the effect of butyrate on mitochondrial HMG-CoA synthase gene expression is exerted in vivo at the transcriptional level, and that trichostatin A (TSA), a specific histone deacetylase inhibitor, also induces transcriptional activity and mRNA expression of the gene in human cell lines derived from colon carcinoma. Using chromatin immunoprecipitation assays, we show that histone deacetylase 1 (HDAC1) is associated with the endogenous mitochondrial HMG-CoA synthase promoter and that TSA induction correlates with hyperacetylation of H4 histone associated with the 5' flanking region of the gene. Overexpression of HDAC1 activity leads consistently to mitochondrial HMG-CoA synthase promoter hypoacetylation and reduces its transcriptional activity. The effect of butyrate and TSA maps to a single Sp1 site present in the proximal promoter of the gene, which is able to bind Sp1 and Sp3 proteins. Interestingly, the binding affinity of Sp1 and Sp3 proteins to the Sp1 site correlates with the TSA responsiveness of the promoter. Using a one-hybrid system (GAL4-Sp1 and GAL4-Sp3), we show that both proteins can mediate responsiveness to TSA in CaCo-2 cells employing distinct mechanisms.
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Affiliation(s)
- Nuria Camarero
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
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8
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Nadal A, Marrero PF, Haro D. Down-regulation of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase gene by insulin: the role of the forkhead transcription factor FKHRL1. Biochem J 2002; 366:289-97. [PMID: 12027802 PMCID: PMC1222772 DOI: 10.1042/bj20020598] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2002] [Revised: 05/23/2002] [Accepted: 05/23/2002] [Indexed: 01/07/2023]
Abstract
Normal physiological responses to carbohydrate shortages cause the liver to increase the production of ketone bodies from the acetyl-CoA generated from fatty acid oxidation. This allows the use of ketone bodies for energy, thereby preserving the limited glucose for use by the brain. This adaptative response is switched off by insulin rapidly inhibiting the expression of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase (HMGCS2) gene, which is a key control site of ketogenesis. We decided to investigate the molecular mechanism of this inhibition. In the present study, we show that FKHRL1, a member of the forkhead in rhabdosarcoma (FKHR) subclass of the Fox family of transcription factors, stimulates transcription from transfected 3-hydroxy-3-methylglutaryl-CoA synthase promoter-luciferase reporter constructs, and that this stimulation is repressed by insulin. An FKHRL1-responsive sequence AAAAATA, located 211 bp upstream of the HMGCS2 gene transcription start site, was identified by deletion analysis. It binds FKHRL1 in vivo and in vitro and confers FKHRL1 responsiveness on homologous and heterologous promoters. If it is mutated, it partially blocks the effect of insulin in HepG2 cells, both in the absence and presence of overexpressed FKHRL1. These results suggest that FKHRL1 contributes to the regulation of HMGCS2 gene expression by insulin.
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Affiliation(s)
- Alícia Nadal
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Barcelona, Avda. Diagonal, 643, E-08028 Barcelona, Spain
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9
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Suzuki J, Shen WJ, Nelson BD, Selwood SP, Murphy GM, Kanehara H, Takahashi S, Oida K, Miyamori I, Kraemer FB, Kanefara H. Cardiac gene expression profile and lipid accumulation in response to starvation. Am J Physiol Endocrinol Metab 2002; 283:E94-E102. [PMID: 12067848 DOI: 10.1152/ajpendo.00017.2002] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Starvation induces many biochemical and histological changes in the heart; however, the molecular events underlying these changes have not been fully elucidated. To explore the molecular response of the heart to starvation, microarray analysis was performed together with biochemical and histological investigations. Serum free fatty acids increased twofold in both 16- and 48-h-fasted mice, and cardiac triglyceride content increased threefold and sixfold in 16- and 48-h-fasted mice, respectively. Electron microscopy showed numerous lipid droplets in hearts of 48-h-fasted mice, whereas fewer numbers of droplets were seen in hearts from 16-h-fasted mice. Expression of 11,000 cardiac genes was screened by microarrays. More than 50 and 150 known genes were detected by differential expression analysis after 16- and 48-h-fasts, respectively. Genes for fatty acid oxidation and gluconeogenesis were increased, and genes for glycolysis were decreased. Many other genes for metabolism, signaling/cell cycle, cytoskeleton, and tissue antigens were affected by fasting. These data provide a broad perspective of the molecular events occurring physiologically in the heart in response to starvation.
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Affiliation(s)
- Jinya Suzuki
- Third Department of Internal Medicine, Fukui Medical University, Fukui 910-1193, Japan.
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Suzuki J, Shen WJ, Nelson BD, Patel S, Veerkamp JH, Selwood SP, Murphy GM, Reaven E, Kraemer FB. Absence of cardiac lipid accumulation in transgenic mice with heart-specific HSL overexpression. Am J Physiol Endocrinol Metab 2001; 281:E857-66. [PMID: 11551864 DOI: 10.1152/ajpendo.2001.281.4.e857] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hormone-sensitive lipase (HSL) hydrolyzes triglyceride (TG) in adipose tissue. HSL is also expressed in heart. To explore the actions of cardiac HSL, heart-specific, tetracycline (Tc)-controlled HSL-overexpressing mice were generated. Tc-responsive element-HSL transgenic (Tg) mice were generated and crossed with myosin heavy chain (MHC)alpha-tTA Tg mice, which express the Tc-responsive transactivator (tTA) in the heart. The double-Tg mice (MHC-HSL) were maintained with doxycycline (Dox) to suppress Tg HSL. Upon removal of Dox, cardiac HSL activity and protein increased 12- and 8-fold, respectively, and the expression was heart specific. Although cardiac TG content increased twofold in control mice after an overnight fast, it did not increase in HSL-induced mice. Electron microscopy showed numerous lipid droplets in the myocardium of fasted control mice, whereas fasted HSL-induced mice showed virtually no droplets. Microarray analysis showed altered expression of cardiac genes for fatty acid oxidation, transcription factors, signaling molecules, cytoskeletal proteins, and histocompatibility antigens in HSL-induced mice. Thus cardiac HSL plays a role in controlling accumulation of triglyceride droplets and can affect the expression of a number of cardiac genes.
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Affiliation(s)
- J Suzuki
- Division of Endocrinology, Stanford University, Stanford 94305, USA
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11
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Lopez JM, Hegardt FG, Haro D. Differential expression of cytosolic and mitochondrial 3-hydroxy-3-methylglutaryl CoA synthases during adipocyte differentiation. Mol Cell Biochem 2001; 217:57-66. [PMID: 11269666 DOI: 10.1023/a:1007284217886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mitochondrial and cytosolic 3-hydroxy-3-methylglutaryl CoA synthase (m-HMS and c-HMS) genes show high identity at the nucleotide and amino acid level, but no homology has been found in the promoter area. The main regulator for c-HMS is SREBP. The best known transcription factor that regulates m-HMS is PPAR alpha. Three types of PPAR, alpha, gamma and delta have been described in vertebrates. Here we found that they display distinct ligand response profiles in the m-HMS promoter. In some conditions PPAR gamma is a significant activator of m-HMS. Thus, the m-HMS gene is transiently expressed during the clonal expansion phase of 3T3-L1 differentiation. We found that C/EBP delta and PPAR gamma activate the m-HMS promoter in 3T3-L1 cells synergistically. This synergistic effect was only observed in the whole promoter (-1148 to +28). A small construct (-116 to +28) which contains the PPRE did not respond to C/EBP delta and/or PPAR gamma. This suggests that a putative C/EBP site lie somewhere between -1148 and -116 bp. We also show that C/EBP delta was more efficient that C/EBP alpha and C/EBP beta to activate the m-HMS promoter. The time course of c-HMS mRNA expression during 3T3-L1 differentiation was different, with a significant increase at terminal adipogenesis. We found that the transcription factor C/EBP alpha did not activate the c-HMS promoter. The differential pattern of expression shown by these two genes, which have a common ancestor, exemplifies refinements of transcriptional control during evolution.
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Affiliation(s)
- J M Lopez
- Departament de Bioquímica i Biologia Molecular, Facultat de Farmàcia, Barcelona, Spain
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12
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Mascaró C, Acosta E, Ortiz JA, Rodríguez JC, Marrero PF, Hegardt FG, Haro D. Characterization of a response element for peroxisomal proliferator activated receptor (PPRE) in human muscle-type carnitine palmitoyltransferase I. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 466:79-85. [PMID: 10709630 DOI: 10.1007/0-306-46818-2_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- C Mascaró
- Department of Biochemistry and Molecular Biology, University of Barcelona, School of Pharmacy, Spain
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13
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Cullingford TE, Bhakoo KK, Peuchen S, Dolphin CT, Clark JB. Regulation of the ketogenic enzyme mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase in astrocytes and meningeal fibroblasts. Implications in normal brain development and seizure neuropathologies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 466:241-51. [PMID: 10709651 DOI: 10.1007/0-306-46818-2_29] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- T E Cullingford
- Department of Neurochemistry, Institute of Neurology, London, U.K
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14
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Mascaró C, Ortiz JA, Ramos MM, Haro D, Hegardt FG. Sterol regulatory element binding protein-mediated effect of fluvastatin on cytosolic 3-hydroxy-3-methylglutaryl-coenzyme A synthase transcription. Arch Biochem Biophys 2000; 374:286-92. [PMID: 10666309 DOI: 10.1006/abbi.1999.1600] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of acute treatment with fluvastatin, a hypocholesteremic drug, on the mRNA levels of several regulatory enzymes of cholesterogenesis and of the LDL receptor were determined in rat liver. Fluvastatin increased the hepatic mRNA levels for HMG-CoA reductase up to 12-fold in 5 weeks of treatment at a daily dose of 6. 3 mg/kg. The effect was less marked in cytosolic HMG-CoA synthase, farnesyl-PP synthase, squalene synthetase, and LDL receptor. SREBP-2 mRNA levels were also increased, but SREBP-1 were not. De novo synthesis of cholesterol in several cultured cells was reduced by increasing concentrations of fluvastatin, and the IC(50) values of fluvastatin in HepG2, CV-1, and CHO cells were respectively 0.01, 0. 05, and 0.1 microM. When CHO cells stably transfected with a chimeric gene composed of the promoter of cytosolic HMG-CoA synthase and the CAT gene as a reporter were incubated with fluvastatin, the CAT gene was overexpressed, an effect which was similar to the cotransfection with the processed form of SREBP-1a. Both ALLN and fluvastatin increased the transcriptional activity of cytosolic HMG-CoA synthase. Mutation in either SRE or NF-Y boxes abolished the increase in transcriptional rate caused by fluvastatin in the promoter of cytosolic HMG-CoA synthase. These results indicate that the increase in transcriptional activity in the HMG-CoA synthase gene attributable to fluvastatin is a consequence of the activation of the proteolytic cleavage of SREBPs by reduced levels of intracellular cholesterol.
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Affiliation(s)
- C Mascaró
- Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, E-08028, Spain
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15
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Pepato MT, Magnani MR, Kettelhut IC, Brunetti IL. Effect of oral vanadyl sulfate treatment on serum enzymes and lipids of streptozotocin-diabetic young rats. Mol Cell Biochem 1999; 198:157-61. [PMID: 10497891 DOI: 10.1023/a:1006917007148] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In this work we investigate the possible toxicity of vanadyl sulfate (VOSO4), a compound capable of reducing hyperglycemia, on the following serum enzymes of diabetic young rats: alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LD) and creatine kinase (CK), as well as its effects on serum lipids. We find that at a concentration of 1 mg/mL VOSO4 has no toxic effect on the liver and muscles of diabetics young rats. These findings suggest that VOSO4 may be an alternative to insulin in the near future, due to its low cost, low toxicity and ready availability.
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Affiliation(s)
- M T Pepato
- Department of Clinical Analysis, Faculty of Pharmaceutical Sciences of Araraquara, UNESP, SP, Brazil
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16
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Abstract
Mitochondrial and cytosolic HMG-CoA synthases are encoded by two different genes. Control of ketogenesis is exerted by transcriptional regulation of mitochondrial HMG-CoA synthase. Fasting, cAMP, and fatty acids increase its transcriptional rate, while refeeding and insulin repress it. Fatty acids increase transcription through peroxisomal proliferator regulatory element (PPRE), to which peroxisome proliferator activated receptor (PPAR) can bind. Other transcription factors such as chicken ovalbumin upstream promoter transcription factor (COUP-TF) and hepatocyte nuclear factor 4 (HNF-4) compete for the PPRE site, modulating the response of PPAR.
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Affiliation(s)
- F G Hegardt
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Barcelona, Spain
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17
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Rodríguez JC, Ortiz JA, Hegardt FG, Haro D. The hepatocyte nuclear factor 4 (HNF-4) represses the mitochondrial HMG-CoA synthase gene. Biochem Biophys Res Commun 1998; 242:692-6. [PMID: 9464279 DOI: 10.1006/bbrc.1997.8032] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have recently shown that the gene for the mitochondrial HMG-CoA synthase is a target for PPAR and that this receptor mediates the induction of this gene by fatty acids. With the aim of gaining further insight into the function and regulation of this gene we examined the effect of other members of the nuclear hormone receptor superfamily on its expression. We previously identified a regulatory element in the mitochondrial HMG-CoA synthase gene promoter that confers transcriptional regulation by PPAR, RXR and the orphan nuclear receptor COUP-TF. In this study we demonstrate a trans-repressing regulatory function for HNF-4 at this same nuclear receptor response element (NRRE). HNF-4 binds to the mitochondrial HMG-CoA synthase NRRE, and, in cotransfection assays in HepG2 cells, it represses PPAR-dependent activation of reporter gene linked to the mitochondrial HMG-CoA synthase gene promoter. These results suggest that the mitochondrial HMG-CoA synthase gene is subject to differential regulation by the interplay of multiple members of the nuclear hormone receptor superfamily.
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Affiliation(s)
- J C Rodríguez
- Unit of Biochemistry, School of Pharmacy, University of Barcelona, Spain
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Thompson GN, Hsu BY, Pitt JJ, Treacy E, Stanley CA. Fasting hypoketotic coma in a child with deficiency of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase. N Engl J Med 1997; 337:1203-7. [PMID: 9337379 DOI: 10.1056/nejm199710233371704] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- G N Thompson
- Murdoch Institute, Parkville, Victoria, Australia
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20
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Rodríguez JC, Ortiz JA, Hegardt FG, Haro D. Chicken ovalbumin upstream-promoter transcription factor (COUP-TF) could act as a transcriptional activator or repressor of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase gene. Biochem J 1997; 326 ( Pt 2):587-92. [PMID: 9291136 PMCID: PMC1218709 DOI: 10.1042/bj3260587] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The chicken ovalbumin upstream-promoter transcription factor (COUP-TF) has a dual effect on the regulation of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase gene. COUP-TF could act as a transcriptional activator or repressor of this gene through different DNA sequences. COUP-TF induces expression of a reporter gene linked to the mitochondrial HMG-CoA synthase gene promoter in human hepatoma HepG2 cells, but represses it in a Leydig tumour cell line (R2C); in both these cell lines the expression of the mitochondrial HMG-CoA synthase gene mimics that of liver and testis. The activation is promoted by a fragment of the gene from coordinates -62 to +28, which contains a GC box and a TATA box, and where no COUP-TF binding site was observed by in vitro DNA binding studies. On the other hand, the COUP-TF inhibitory effect is mainly due to repression of peroxisome-proliferator-activated receptor-dependent activation of the gene, interacting with the region from -104 to -92. To our knowledge this work represents the second example of a target gene for COUP-TF I that could be either activated or repressed by the action of this receptor through different DNA sequences of the same gene.
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Affiliation(s)
- J C Rodríguez
- Unitat de Bioquímica, Facultat de Farmàcia, Barcelona, Spain
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21
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Boukaftane Y, Mitchell GA. Cloning and characterization of the human mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase gene. Gene 1997; 195:121-6. [PMID: 9305755 DOI: 10.1016/s0378-1119(97)00067-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We report the characterization of lambda and P1 phage clones containing the entire human mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase (mHS) gene. The human mHS locus (HMGCS2) on chromosome 1p12-13 spans 25 kb and contains 10 exons. Exon 1 contains most of the mitochondrial leader, consistent with a recent hypothesis of the evolution of the ketogenic pathway. By primer extension and cDNA amplification (RACE-PCR) we localized the transcription start point (tsp) to 60 bp upstream of the initiation codon. Nine blocks of conserved sequence were identified by comparing the 5' flanking regions of the mHS genes of human and rat. The 5' flanking region contains potential binding sites for TATA-binding protein, Sp1, nuclear factor 1 (NF1), CAAT-box binding protein (C/EBP), hepatocyte nuclear factors 1 and 5 (HNF1, HNF5) and activator proteins 1 and 2 (AP1, AP2).
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Affiliation(s)
- Y Boukaftane
- Service de génétique médicale, Hôpital Ste-Justine, Université de Montréal, Québec, Canada
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22
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Adams SH, Alho CS, Asins G, Hegardt FG, Marrero PF. Gene expression of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase in a poorly ketogenic mammal: effect of starvation during the neonatal period of the piglet. Biochem J 1997; 324 ( Pt 1):65-73. [PMID: 9164842 PMCID: PMC1218402 DOI: 10.1042/bj3240065] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The low ketogenic capacity of pigs correlates with a low activity of mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase. To identify the molecular mechanism controlling such activity, we isolated the pig cDNA encoding this enzyme and analysed changes in mRNA levels and mitochondrial specific activity induced during development and starvation. Pig mitochondrial synthase showed a tissue-specific expression pattern. As with rat and human, the gene is expressed in liver and large intestine; however, the pig differs in that mRNA was not detected in testis, kidney or small intestine. During development, pig mitochondrial HMG-CoA synthase gene expression showed interesting differences from that in the rat: (1) there was a 2-3 week lag in the postnatal induction; (2) the mRNA levels remained relatively abundant through the suckling-weaning transition and at maturity, in contrast with the fall observed in rats at similar stages of development; and (3) the gene expression was highly induced by fasting during the suckling, whereas no such change in mitochondrial HMG-CoA synthase mRNA levels has been observed in rat. The enzyme activity of mitochondrial HMG-CoA synthase increased 27-fold during starvation in piglets, but remained one order of magnitude lower than rats. These results indicate that post-transcriptional mechanism(s) and/or intrinsic differences in the encoded enzyme are responsible for the low activity of pig HMG-CoA synthase observed throughout development or after fasting.
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Affiliation(s)
- S H Adams
- Unit of Biochemistry, School of Pharmacy, University of Barcelona, Avda. Diagonal, 643, 08028 Barcelona, Spain
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Affiliation(s)
- J K Reddy
- Department of Pathology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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24
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Serra D, Bellido D, Asins G, Arias G, Vilaró S, Hegardt FG. The expression of mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme-A synthase in neonatal rat intestine and liver is under transcriptional control. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 237:16-24. [PMID: 8620869 DOI: 10.1111/j.1432-1033.1996.0016n.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HOMeGlt-CoA) synthase regulates ketogenesis in the liver of adult rat and in the intestine and liver of neonatal animals but whose mechanisms of regulation have not been fully defined. To investigate transcriptional control of this gene in intestine and liver of suckling rats a quantitative PCR amplification of the pre-mRNA (heteronuclear RNA), compose of part of the first exon and of the first intron, was carried out. Results show that the intestinal pre-mRNA for mitochondrial HOMeGlt-CoA synthase from suckling rats follows a pattern that is nearly identical to that of mature mRNA, with maximum levels on the ninth postnatal day then decreasing smoothly so that at weaning there is no transcriptional activity. Mitochondrial HOMeGlt-CoA synthase protein follows a pattern that is identical to the pre-mRNA and mature mRNA, suggesting no translational regulation. The changes in transcriptional activity are not produced by the presence of an alternative promoter, since the transcription-initiation site is identical in several tissues assayed, including intestine and liver. Enterocytes are the only intestinal cells that express this ketogenic enzyme, as deduced from immunolocalization experiments. The mature intestinal protein is located in mitochondria and not in the cytosol, which coincides with what is found in liver. By using analogous techniques we conclude that hepatic pre-mRNA of mitochondrial HOMeGlt-CoA synthase from suckling rats follows a pattern of expression identical to that of mature hepatic mRNA, which also suggests a transcriptional modulation of this gene in the liver of neonatal rats.
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Affiliation(s)
- D Serra
- Unit of Biochemistry, School of Pharmacy, University of Barcelona, Spain
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25
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Serra D, Fillat C, Matas R, Bosch F, Hegardt FG. Tissue-specific expression and dietary regulation of chimeric mitochondrial 3-hydroxy-3-methylglutaryl coenzyme A synthase/human growth hormone gene in transgenic mice. J Biol Chem 1996; 271:7529-34. [PMID: 8631784 DOI: 10.1074/jbc.271.13.7529] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We have studied the role of the mitochondrial 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) synthase gene in regulating ketogenesis. The gene exhibits expression in various tissues and it is regulated in a tissue-specific manner. To investigate the underlying mechanisms of this expression, we linked a 1148-base-pair portion of the mitochondrial HMG-CoA synthase promoter to the human growth hormone (hGH) gene and analyzed the expression of the hGH reporter gene in transgenic mice. mRNA levels of hGH were observed in liver, testis, ovary, stomach, colon, cecum, brown adipose tissue, spleen, adrenal glands, and mammary glands from adult mice, and also in liver and stomach, duodenum, jejunum, brown adipose tissue, and heart of suckling mice. There was no expression either in kidney or in any other nonketogenic tissue. The comparison between these data and those of the endogenous mitochondrial HMG-CoA synthase gene suggests that the 1148 base pairs of the promoter contain the elements necessary for expression in liver and testis, but an enhancer is necessary for full expression in intestine of suckling animals and that a silencer prevents expression in stomach, brown adipose tissue, spleen, adrenal glands, and mammary glands in wild type adult mice. In starvation, transgenic mice showed higher expression in liver than did wild type. Both refeeding and insulin injection reduced the expression. Fat diets, composed in each case of different fatty acids, produced similar expression levels, respectively, to those found in wild type animals, suggesting that long-, medium-, and short-chain fatty acids may exert a positive influence on the transcription rate in this 1148-base-pair portion of the promoter. The ketogenic capacity of liver and the blood ketone body levels were equal in transgenic mice and in nontransgenic mice.
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Affiliation(s)
- D Serra
- Unit of Biochemistry, University of Barcelona, School of Pharmacy, Spain
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26
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Jacob HJ, Brown DM, Bunker RK, Daly MJ, Dzau VJ, Goodman A, Koike G, Kren V, Kurtz T, Lernmark A. A genetic linkage map of the laboratory rat, Rattus norvegicus. Nat Genet 1995; 9:63-9. [PMID: 7704027 DOI: 10.1038/ng0195-63] [Citation(s) in RCA: 349] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We report the construction of the first complete genetic linkage map of the laboratory rat. By testing 1171 simple sequence length polymorphisms (SSLPs), we have identified 432 markers that show polymorphisms between the SHR and BN rat strains and mapped them in a single (SHR x BN) F2 intercross. The loci define 21 large linkage groups corresponding to the 21 rat chromosomes, together with a pair of nearby markers on chromosome 9 that are not linked to the rest of the map. Because 99.5% of the markers fall into one of the 21 large linkage groups, the maps appear to cover the vast majority of the rat genome. The availability of the map should facilitate whole genome scans for genes underlying qualitative and quantitative traits relevant to mammalian physiology and pathobiology.
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Affiliation(s)
- H J Jacob
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown
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27
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Rodríguez J, Gil-Gómez G, Hegardt F, Haro D. Peroxisome proliferator-activated receptor mediates induction of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase gene by fatty acids. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32234-2] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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28
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Ayté J, Gil-Gómez G, Hegardt FG. Methylation of the regulatory region of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase gene leads to its transcriptional inactivation. Biochem J 1993; 295 ( Pt 3):807-12. [PMID: 7694571 PMCID: PMC1134633 DOI: 10.1042/bj2950807] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase gene is expressed in a limited set of tissues in the adult rat. Methylation of the 5' flanking region of the gene in vitro leads to its transcriptional inactivation when transfected in hepatoma-derived cell lines. In liver and kidney, expression of the gene correlates inversely with its degree of methylation, indicating that the methylation of the 5' flanking region and the first exon of the gene may be one of the factors responsible for the repression of its transcription. During the fetal/neonatal transition, a process of selective undermethylation of specific sites takes place in the 5' flanking region of the mitochondrial HMG-CoA synthase gene. Moreover, treatment with the hypomethylating agent 5-azacytidine of a hepatoma-derived cell line that presents barely detectable levels of mitochondrial HMG-CoA synthase mRNA leads to a significant increase in the mRNA levels. These results point to methylation as one of the regulatory mechanisms that operate on the mitochondrial HMG-CoA synthase gene.
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Affiliation(s)
- J Ayté
- Unitat de Bioquímica, Facultat de Farmàcia, Universitat de Barcelona, Spain
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