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Fatty acid synthesis and cancer: Aberrant expression of the ACACA and ACACB genes increases the risk for cancer. Meta Gene 2020. [DOI: 10.1016/j.mgene.2020.100798] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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2
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Kaulage M, Maji B, Bhat J, Iwasaki Y, Chatterjee S, Bhattacharya S, Muniyappa K. Discovery and Structural Characterization of G-quadruplex DNA in Human Acetyl-CoA Carboxylase Gene Promoters: Its Role in Transcriptional Regulation and as a Therapeutic Target for Human Disease. J Med Chem 2016; 59:5035-50. [PMID: 27058681 DOI: 10.1021/acs.jmedchem.6b00453] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Accumulating evidence suggests that G-quadruplexes play vital roles in gene expression, DNA replication, and recombination. Three distinct promoters (PI, PII, and PIII) regulate human acetyl-CoA carboxylase 1 (ACC1) gene expression. In this study, we asked whether the G-rich sequences within the human ACC1 (PI and PII) promoters can form G-quadruplex structures and regulate normal DNA transactions. Using multiple complementary methods, we show that G-rich sequences of PI and PII promoters form intramolecular G-quadruplex structures and then establish unambiguously the topologies of these structures. Importantly, G-quadruplex formation in ACC1 gene promoter region blocks DNA replication and suppresses transcription, and this effect was further augmented by G-quadruplex stabilizing ligands. Altogether, these results are consistent with the notion that G-quadruplex structures exist within the human ACC1 gene promoter region, whose activity can be suppressed by G-quadruplex stabilizing ligands, thereby revealing a novel regulatory mechanism of ACC1 gene expression and as a possible therapeutic target.
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Affiliation(s)
| | | | - Jyotsna Bhat
- Department of Biophysics, Bose Institute , Kolkata 700054, India
| | - Yasumasa Iwasaki
- Department of Endocrinology, Metabolism, and Nephrology, Kochi Medical School, Kochi University , Nankoku 780-8520, Japan
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Inhibition of gene expression of carnitine palmitoyltransferase I and heart fatty acid binding protein in cyclophosphamide and ifosfamide-induced acute cardiotoxic rat models. Cardiovasc Toxicol 2015; 14:232-42. [PMID: 24469765 DOI: 10.1007/s12012-014-9247-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This study investigated whether cyclophosphamide (CP) and ifosfamide (IFO) therapy alters the expression of the key genes engaged in long-chain fatty acid (LCFA) oxidation outside rat heart mitochondria, and if so, whether these alterations should be viewed as a mechanism during CP- and IFO-induced cardiotoxicity. Adult male Wistar albino rats were assigned to one of the six treatment groups: Rats in group 1 (control) and group 2 (L-carnitine) were injected intraperitoneal (i.p.) with normal saline and L-carnitine (200 mg/kg/day), respectively, for 10 successive days. Animals in group 3 (CP group) were injected i.p. with normal saline for 5 days before and 5 days after a single dose of CP (200 mg/kg, i.p.). Rats in group 4 (IFO group) received normal saline for 5 successive days followed by IFO (50 mg/kg/day, i.p.) for 5 successive days. Rats in group 5 (CP-carnitine supplemented) were given the same doses of L-carnitine as group 2 for 5 days before and 5 days after a single dose of CP as group 3. Rats in group 6 (IFO-carnitine supplemented) were given the same doses of L-carnitine as group 2 for 5 days before and 5 days concomitant with IFO as group 4. Immediately, after the last dose of the treatment protocol, blood samples were withdrawn and animals were killed for biochemical, histopathological and gene expression studies. Treatment with CP and IFO significantly decreased expression of heart fatty acid binding protein (H-FABP) and carnitine palmitoyltransferase I (CPT I) genes in cardiac tissues. Moreover, CP but not IFO significantly increased acetyl-CoA carboxylase2 mRNA expression. Conversely, IFO but not CP significantly decreased mRNA expression of malonyl-CoA decarboxylase. Both CP and IFO significantly increased serum lactate dehydrogenase, creatine kinase isoenzyme MB and malonyl-CoA content and histopathological lesions in cardiac tissues. Interestingly, carnitine supplementation completely reversed all the biochemical, histopathological and gene expression changes induced by CP and IFO to the control values, except CPT I mRNA, and protein expression remained inhibited by IFO. Data from the current study suggest, for the first time, that (1) CP and IFO therapy is associated with the inhibition of the expression of H-FABP and CPT I genes in cardiac tissues with the consequent inhibition of mitochondrial transport and oxidation of LCFA. (2) The progressive increase in cardiotoxicity enzymatic indices and the decrease in H-FABP and CPT I expression may point to the possible contribution of these genes to CP- and IFO-induced cardiotoxicity.
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Imbriolo J, Mapanga RF, Essop MF. The hexosamine biosynthetic pathway induces gene promoter activity of acetyl-CoA carboxylase beta. Biochem Biophys Res Commun 2014; 452:734-9. [PMID: 25195817 DOI: 10.1016/j.bbrc.2014.08.142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 08/26/2014] [Indexed: 12/30/2022]
Abstract
The cardiac isoform of acetyl-CoA carboxylase (ACCβ) produces malonyl-CoA, a potent inhibitor of mitochondrial fatty acid (FA) uptake. Higher ACCβ activity decreases FA utilization, potentially leading to intracellular myocardial lipid accumulation and insulin resistance (IR). Since increased hexosamine biosynthetic pathway (HBP) flux is linked to IR onset, we hypothesized that HBP activation leads to the induction of ACCβ gene promoter activity. Rat H9c2 cardio-myoblasts were transiently transfected with a 1317bp human ACCβ promoter-luciferase construct (pPIIβ-1317)±an expression construct encoding the HBP rate-limiting step, i.e., glutamine:fructose 6-phosphate amidotransferase (GFAT)±various HBP modulators. The administration of l-glutamine (HBP substrate) dose-dependently increased, while HBP inhibitors attenuated pPIIβ-1317 activity. Co-transfections with dominant-negative GFAT constructs diminished pPIIβ-1317 activity. To explore underlying transcriptional mechanisms, we co-transfected with upstream stimulatory factor (USF) expression constructs and found that USF2 induced pPIIβ-1317 activity vs. controls. Moreover, co-transfection of a GFAT expression construct+USF reporter-promoter construct (with consensus USF binding elements) led to induction of pPIIβ-1317 activity vs. controls. We next performed transfections with GFAT±full length ACCβ and seven truncated promoter-luciferase constructs, respectively. Here GFAT-mediated ACCβ promoter induction was blunted when co-transfected with the pPIIβ-38/+65 deletion construct indicating that USF2 binds to the proximal ACCβ promoter region (near start codon). Our study demonstrates that HBP activation induces ACCβ gene promoter activity in H9c2 cells via USF2. We propose that such ACCβ induction may elicit serious downstream effects, e.g. the inhibition of FA β-oxidation and the onset of IR.
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Affiliation(s)
- Jamie Imbriolo
- Cardio-Metabolic Research Group (CMRG), Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Rudo F Mapanga
- Cardio-Metabolic Research Group (CMRG), Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
| | - M Faadiel Essop
- Cardio-Metabolic Research Group (CMRG), Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa.
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Zu X, Zhong J, Luo D, Tan J, Zhang Q, Wu Y, Liu J, Cao R, Wen G, Cao D. Chemical genetics of acetyl-CoA carboxylases. Molecules 2013; 18:1704-19. [PMID: 23358327 PMCID: PMC6269866 DOI: 10.3390/molecules18021704] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 01/03/2013] [Accepted: 01/11/2013] [Indexed: 12/16/2022] Open
Abstract
Chemical genetic studies on acetyl-CoA carboxylases (ACCs), rate-limiting enzymes in long chain fatty acid biosynthesis, have greatly advanced the understanding of their biochemistry and molecular biology and promoted the use of ACCs as targets for herbicides in agriculture and for development of drugs for diabetes, obesity and cancers. In mammals, ACCs have both biotin carboxylase (BC) and carboxyltransferase (CT) activity, catalyzing carboxylation of acetyl-CoA to malonyl-CoA. Several classes of small chemicals modulate ACC activity, including cellular metabolites, natural compounds, and chemically synthesized products. This article reviews chemical genetic studies of ACCs and the use of ACCs for targeted therapy of cancers.
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Affiliation(s)
- Xuyu Zu
- Institute of Clinical Medicine, the First Affiliated Hospital, University of South China, Hengyang 421001, Hunan, China
| | - Jing Zhong
- Institute of Clinical Medicine, the First Affiliated Hospital, University of South China, Hengyang 421001, Hunan, China
| | - Dixian Luo
- Institute of Translational Medicine & Department of Laboratory Medicine, the First People’s Hospital of Chenzhou, 102 Luojiajing Road, Chenzhou 423000, Hunan, China
| | - Jingjing Tan
- Institute of Clinical Medicine, the First Affiliated Hospital, University of South China, Hengyang 421001, Hunan, China
| | - Qinghai Zhang
- Institute of Clinical Medicine, the First Affiliated Hospital, University of South China, Hengyang 421001, Hunan, China
| | - Ying Wu
- Institute of Clinical Medicine, the First Affiliated Hospital, University of South China, Hengyang 421001, Hunan, China
| | - Jianghua Liu
- Institute of Clinical Medicine, the First Affiliated Hospital, University of South China, Hengyang 421001, Hunan, China
| | - Renxian Cao
- Institute of Clinical Medicine, the First Affiliated Hospital, University of South China, Hengyang 421001, Hunan, China
- Authors to whom correspondence should be addressed; E-Mails: (R.C.); (D.C.); Tel.: +86-217-545-9703 (D.C.); Fax: +86-217-545-9718 (D.C.)
| | - Gebo Wen
- Institute of Clinical Medicine, the First Affiliated Hospital, University of South China, Hengyang 421001, Hunan, China
| | - Deliang Cao
- Department of Microbiology, Immunology and Cell Biology, Simmons Cancer Institute, Southern Illinois University School of Medicine, 913 N. Rutledge Street, Springfield, IL 62794, USA
- Authors to whom correspondence should be addressed; E-Mails: (R.C.); (D.C.); Tel.: +86-217-545-9703 (D.C.); Fax: +86-217-545-9718 (D.C.)
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Myogenic regulatory factors regulate M-cadherin expression by targeting its proximal promoter elements. Biochem J 2010; 428:223-33. [PMID: 20334626 DOI: 10.1042/bj20100250] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
M- and N-cadherin are members of the Ca(2+)-dependent cell-cell adhesion molecule family. M-cadherin is expressed predominantly in developing skeletal muscles and has been implicated in terminal myogenic differentiation, particularly in myoblast fusion. N-cadherin-mediated cell-cell adhesion also plays an important role in skeletal myogenesis. In the present study, we found that both genes were differentially expressed in C2C12 and Sol8 myoblasts during myogenic differentiation and that the expression of M-cadherin was preferentially enhanced in slow-twitch muscle. Interestingly, most MRFs (myogenic regulatory factors) significantly activated the promoter of M-cadherin, but not that of N-cadherin. In line with this, overexpression of MyoD in C3H10T1/2 fibroblasts strongly induced endogenous M-cadherin expression. Promoter analysis in silico and in vitro identified an E-box (from -2 to +4) abutting the transcription initiation site within the M-cadherin promoter that is bound and differentially activated by different MRFs. The activation of the M-cadherin promoter by MRFs was also modulated by Bhlhe40 (basic helix-loop-helix family member e40). Finally, chromatin immunoprecipitation proved that MyoD as well as myogenin binds to the M-cadherin promoter in vivo. Taken together, these observations identify a molecular mechanism by which MRFs regulate M-cadherin expression directly to ensure the terminal differentiation of myoblasts.
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Zhang K, Sha J, Harter ML. Activation of Cdc6 by MyoD is associated with the expansion of quiescent myogenic satellite cells. ACTA ACUST UNITED AC 2010; 188:39-48. [PMID: 20048262 PMCID: PMC2812847 DOI: 10.1083/jcb.200904144] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Cdc6, which alters chromatin ultrastructure to allow DNA replication in muscle stem cells transitioning out of quiescence, is identified as a target of the MyoD transcription factor. MyoD is a transcriptional factor that is required for the differentiation of muscle stem cells (satellite cells). In this study, we describe a previously unknown function for MyoD in regulating a gene (Cdc6) that is vital to endowing chromatin with the capability of replicating DNA. In C2C12 and primary mouse myoblasts, we show that MyoD can occupy an E-box within the promoter of Cdc6 and that this association, along with E2F3a, is required for its activity. MyoD and Cdc6 are both expressed after quiescent C2C12 myoblasts or satellite cells in association with myofibers are stimulated for growth, but MyoD appears at least 2–3 h earlier than Cdc6. Finally, knockdown of MyoD impairs the ability of C2C12 cells to express Cdc6 after leaving quiescence, and as a result, they cannot fully progress into S phase. Our results define a mechanism by which MyoD helps myogenic satellite cells to enter into the first round of DNA replication after transitioning out of quiescence.
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Affiliation(s)
- Keman Zhang
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA
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Continuous fat oxidation in acetyl-CoA carboxylase 2 knockout mice increases total energy expenditure, reduces fat mass, and improves insulin sensitivity. Proc Natl Acad Sci U S A 2007; 104:16480-5. [PMID: 17923673 DOI: 10.1073/pnas.0706794104] [Citation(s) in RCA: 244] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Acetyl-CoA carboxylase 2 (ACC)2 is a key regulator of mitochondrial fat oxidation. To examine the impact of ACC2 deletion on whole-body energy metabolism, we measured changes in substrate oxidation and total energy expenditure in Acc2(-/-) and WT control mice fed either regular or high-fat diets. To determine insulin action in vivo, we also measured whole-body insulin-stimulated liver and muscle glucose metabolism during a hyperinsulinemic-euglycemic clamp in Acc2(-/-) and WT control mice fed a high-fat diet. Contrary to previous studies that have suggested that increased fat oxidation might result in lower glucose oxidation, both fat and carbohydrate oxidation were simultaneously increased in Acc2(-/-) mice. This increase in both fat and carbohydrate oxidation resulted in an increase in total energy expenditure, reductions in fat and lean body mass and prevention from diet-induced obesity. Furthermore, Acc2(-/-) mice were protected from fat-induced peripheral and hepatic insulin resistance. These improvements in insulin-stimulated glucose metabolism were associated with reduced diacylglycerol content in muscle and liver, decreased PKC activity in muscle and PKCepsilon activity in liver, and increased insulin-stimulated Akt2 activity in these tissues. Taken together with previous work demonstrating that Acc2(-/-) mice have a normal lifespan, these data suggest that Acc2 inhibition is a viable therapeutic option for the treatment of obesity and type 2 diabetes.
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Abstract
Acetyl-CoA carboxylase (ACC) catalyses the formation of malonyl-CoA, an essential substrate for fatty acid synthesis in lipogenic tissues and a key regulatory molecule in muscle, brain and other tissues. ACC contributes importantly to the overall control of energy metabolism and has provided an important model to explore mechanisms of enzyme control and hormone action. Mammalian ACCs are multifunctional dimeric proteins (530–560 kDa) with the potential to further polymerize and engage in multiprotein complexes. The enzymatic properties of ACC are complex, especially considering the two active sites, essential catalytic biotin, the three-substrate reaction and effects of allosteric ligands. The expression of the two major isoforms and splice variants of mammalian ACC is tissue-specific and responsive to hormones and nutritional status. Key regulatory elements and cognate transcription factors are still being defined. ACC specific activity is also rapidly modulated, being increased in response to insulin and decreased following exposure of cells to catabolic hormones or environmental stress. The acute control of ACC activity is the product of integrated changes in substrate supply, allosteric ligands, the phosphorylation of multiple serine residues and interactions with other proteins. This review traces the path and implications of studies initiated with Dick Denton in Bristol in the late 1970s, through to current proteomic and other approaches that have been consistently challenging and immensely rewarding.
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Makaula S, Adam T, Essop MF. Upstream stimulatory factor 1 transactivates the human gene promoter of the cardiac isoform of acetyl-CoA carboxylase. Arch Biochem Biophys 2005; 446:91-100. [PMID: 16376850 DOI: 10.1016/j.abb.2005.10.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 10/26/2005] [Accepted: 10/29/2005] [Indexed: 11/26/2022]
Abstract
E-box cis-elements act as binding sites for upstream stimulatory factors (USFs), putative glucose-responsive transcriptional modulators. Since four E-boxes were identified on the human ACCbeta promoter, we hypothesized that USF1 induces ACCbeta expression in a glucose-dependent manner. Here, murine cardiac ACCbeta expression was significantly increased in response to high carbohydrate re-feeding after fasting. However, transfection studies showed no difference in ACCbeta promoter activity in neonatal cardiomyocytes and CV-1 fibroblasts after low (5.5mM) and high (25 mM) glucose exposure. USF1 overexpression significantly increased ACCbeta promoter activity in both cell lines under low glucose conditions. With high glucose exposure, USF1 further induced ACCbeta promoter activity only in CV-1 fibroblasts. USF1-induced ACCbeta promoter responsiveness was markedly attenuated when co-transfecting cardiomyocytes with a -93/+65 or -38/+65 promoter deletion construct (lacking E-boxes 1-3). Thus, USF1 transactivates the human ACCbeta promoter in the heart, likely through an E-box cis-element located close to the transcription start site.
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Affiliation(s)
- Siyanda Makaula
- Hatter Heart Research Institute, University of Cape Town Faculty of Health Sciences, Observatory 7925, South Africa
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Barber MC, Price NT, Travers MT. Structure and regulation of acetyl-CoA carboxylase genes of metazoa. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1733:1-28. [PMID: 15749055 DOI: 10.1016/j.bbalip.2004.12.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Revised: 11/02/2004] [Accepted: 12/01/2004] [Indexed: 11/16/2022]
Abstract
Acetyl-CoA carboxylase (ACC) plays a fundamental role in fatty acid metabolism. The reaction product, malonyl-CoA, is both an intermediate in the de novo synthesis of long-chain fatty acids and also a substrate for distinct fatty acyl-CoA elongation enzymes. In metazoans, which have evolved energy storage tissues to fuel locomotion and to survive periods of starvation, energy charge sensing at the level of the individual cell plays a role in fuel selection and metabolic orchestration between tissues. In mammals, and probably other metazoans, ACC forms a component of an energy sensor with malonyl-CoA, acting as a signal to reciprocally control the mitochondrial transport step of long-chain fatty acid oxidation through the inhibition of carnitine palmitoyltransferase I (CPT I). To reflect this pivotal role in cell function, ACC is subject to complex regulation. Higher metazoan evolution is associated with the duplication of an ancestral ACC gene, and with organismal complexity, there is an increasing diversity of transcripts from the ACC paraloges with the potential for the existence of several isozymes. This review focuses on the structure of ACC genes and the putative individual roles of their gene products in fatty acid metabolism, taking an evolutionary viewpoint provided by data in genome databases.
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Affiliation(s)
- Michael C Barber
- Hannah Research Institute, Ayr, KA6 5HL, Scotland, United Kingdom.
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Oh SY, Lee MY, Kim JM, Yoon S, Shin S, Park YN, Ahn YH, Kim KS. Alternative usages of multiple promoters of the acetyl-CoA carboxylase beta gene are related to differential transcriptional regulation in human and rodent tissues. J Biol Chem 2004; 280:5909-16. [PMID: 15590647 DOI: 10.1074/jbc.m409037200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acetyl-CoA carboxylase beta (ACCbeta) is a critical enzyme in the regulation of fatty acid oxidation and is dominantly expressed in the skeletal muscle, heart, and liver. It has been established that two promoters, P-I and P-II, control the transcription of the ACCbeta gene. However, the precise mechanism involved in controlling tissue-specific gene expression of ACCbeta is largely unknown yet. In this study we revealed that promoter P-I, active in the skeletal muscle and heart but not in the liver, could be activated by myogenic regulatory factors and retinoid X receptors in a synergistic manner. Moreover, P-I was also activated markedly by the cardiac-specific transcription factors, Csx/Nkx2.5 and GATA4. These results suggest that the proper stimulation of P-I by these tissue-specific transcription factors is important for the expression of ACCbeta according to the tissue types. In addition, CpG sites around human exon 1a transcribed by P-I are half-methylated in muscle but completely methylated in the liver, where P-I is absolutely inactive. In humans, the skeletal muscle uses P-II as well as P-I, whereas only P-I is active in rat skeletal muscle. The proximal myogenic regulatory factor-binding sites in human P-II, which are not conserved in rat P-II, might contribute to this difference in P-II usage between human and rat skeletal muscle. Hepatoma-derived cell lines primarily use another novel promoter located about 3 kilobases upstream of P-I, designated as P-O. This study is the first to explain the mechanisms underlying the differential regulation of ACCbeta gene expression between tissues in living organisms.
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Affiliation(s)
- So-Young Oh
- Department of Biochemistry and Molecular Biology, Brain Korea 21 Project for Medical Science, Institute of Genetic Science, Yonsei University College of Medicine, 134 Shinchondong Seodaemungu, Seoul 120-752, Korea
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Travers MT, Vallance AJ, Clegg RA, Thomson R, Price NT, Barber MC. Characterisation of an N-terminal variant of acetyl-CoA carboxylase-α: expression in human tissues and evolutionary aspects. Biochim Biophys Acta Mol Cell Biol Lipids 2003; 1634:97-106. [PMID: 14643797 DOI: 10.1016/j.bbalip.2003.09.005] [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: 11/26/2022]
Abstract
mRNA encoding a variant acetyl-CoA carboxylase (ACC)-alpha isozyme, transcribed from a downstream promoter, PIII, was detected in human tissues. Such exon 5A-containing transcripts (E5A-mRNA) encode ACC-alpha with a distinct N-terminus, with 15/17 residues identical to those encoded by the ovine mRNA. In the current study we used antisera directed against the E5A N-terminus to verify that ovine E5A translates are present in tissues consistent with the distribution of E5A-mRNA. The presence of E5A alters the context of adjacent regulatory phosphorylation sites in E6, which may indicate altered regulation of activity for this isozyme. Sequences with high identity to the proximal promoter of PIII and E5A are present in the mouse and rat ACC-alpha genes, however, the coding region of E5A is not conserved, and E5A transcripts are not detected in tissues. Thus E5A must have been present in a common ancestor of rodents, primates, and ruminants, and has become nonfunctional in the former. A minor human PIII-derived mRNA containing an additional 111-bp sequence encoded by a downstream exon, E5B, was also detected. E5B encodes an in-frame stop-codon such that the E5A open-reading frame is terminated, however, ACC-alpha translation may be re-initiated from a downstream AUG in E6, potentially generating an isozyme lacking the N-terminal phosphorylation sites. Transcription of human ACC-alpha from at least three promoters and the potential to generate ACC-alpha isozymes with differential susceptibilities to phosphorylation indicate that the regulation of fatty acid synthesis in human tissues is likely to be complex.
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Affiliation(s)
- Maureen T Travers
- Cell Biochemistry Group, Hannah Research Institute, Hannah Research Park, Ayr, Scotland KA6 5HL, UK
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Oh SY, Park SK, Kim JW, Ahn YH, Park SW, Kim KS. Acetyl-CoA carboxylase beta gene is regulated by sterol regulatory element-binding protein-1 in liver. J Biol Chem 2003; 278:28410-7. [PMID: 12764144 DOI: 10.1074/jbc.m300553200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acetyl-CoA carboxylase (ACC) exists as two major isoforms originated from separate genes: ACCalpha (or ACC1) and ACCbeta (or ACC2). Previous data revealed that ACCbeta has two forms of mRNA with different 5'-untranslated regions derived by different usage of promoters, I and II, in human. In this study, we revealed that ACCbeta expression in liver is markedly stimulated by food intake at the transcriptional level. In the process of this induction in rat liver, promoter II plays the major role in regulating the expression of ACCbeta gene. The transient transfection with promoter II-luciferase reporters elucidated that the region from -93 to -38 nucleotides is important for the responsiveness to sterol regulatory element-binding protein-1 (SREBP-1), which is known to be the principle mediator for the stimulation of gene transcriptions by insulin and diet. The Sp1-binding site (-71 to -66) and neighboring two conserved SREs (-62 to -44) play a critical role in the stimulation of ACCbeta gene expression by SREBP-1. In vivo chromatin immunoprecipitation assay revealed that SREBP-1 directly bound to ACCbeta promoter II in liver, and its binding was regulated by the diet. This study provides evidence that ACCbeta expression in liver is regulated at the transcriptional level by the direct interaction of SREBP-1 with promoter II.
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Affiliation(s)
- So-Young Oh
- Department of Biochemistry and Molecular Biology, Institute of Genetic Science, Yonsei University College of Medicine, 134 Shinchondong Seodaemungu, Seoul 120-752, Korea
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Dedieu S, Mazères G, Dourdin N, Cottin P, Brustis JJ. Transactivation of capn2 by myogenic regulatory factors during myogenesis. J Mol Biol 2003; 326:453-65. [PMID: 12559913 DOI: 10.1016/s0022-2836(02)01310-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The calcium-activated cysteine protease m-calpain plays a pivotal role during the earlier stages of myogenesis, particularly during fusion. The enzyme is a heterodimer, encoded by the genes capn2, for the large subunit, and capn4, for the small subunit. To study the regulation of m-calpain, the DNA sequence upstream of capn2 was analyzed for promoter elements, revealing the existence of five consensus-binding sites (E-box) for several myogenic regulatory factors and one binding site for myocyte enhancer factor-2 (MEF-2). Transient transfections with reporter gene constructs containing the E-box revealed that MyoD presents a high level of transactivation of reporter constructs containing this region, in particular the sequences including the MEF-2/E4-box. In addition, over-expression of various myogenic factors demonstrated that MyoD and myogenin with much less efficiency, can up-regulate capn2, both singly and synergistically, while Myf5 has no effect on synthesis of the protease. Experiments with antisense oligonucleotides directed against each myogenic factor revealed that MyoD plays a specific and pivotal role during capn2 regulation, and cannot be replaced wholly by myogenin and Myf5.
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Affiliation(s)
- Stéphane Dedieu
- Laboratoire Biosciences de l'Aliment, ISTAB-USC-INRA 429, Université Bordeaux I, Avenue des Facultés, 33405 Talence Cedex, France
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Spiller MP, Kambadur R, Jeanplong F, Thomas M, Martyn JK, Bass JJ, Sharma M. The myostatin gene is a downstream target gene of basic helix-loop-helix transcription factor MyoD. Mol Cell Biol 2002; 22:7066-82. [PMID: 12242286 PMCID: PMC139803 DOI: 10.1128/mcb.22.20.7066-7082.2002] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Myostatin is a negative regulator of myogenesis, and inactivation of myostatin leads to heavy muscle growth. Here we have cloned and characterized the bovine myostatin gene promoter. Alignment of the upstream sequences shows that the myostatin promoter is highly conserved during evolution. Sequence analysis of 1.6 kb of the bovine myostatin gene upstream region revealed that it contains 10 E-box motifs (E1 to E10), arranged in three clusters, and a single MEF2 site. Deletion and mutation analysis of the myostatin gene promoter showed that out of three important E boxes (E3, E4, and E6) of the proximal cluster, E6 plays a significant role in the regulation of a reporter gene in C(2)C(12) cells. We also demonstrate by band shift and chromatin immunoprecipitation assay that the E6 E-box motif binds to MyoD in vitro and in vivo. Furthermore, cotransfection experiments indicate that among the myogenic regulatory factors, MyoD preferentially up-regulates myostatin promoter activity. Since MyoD expression varies during the myoblast cell cycle, we analyzed the myostatin promoter activity in synchronized myoblasts and quiescent "reserve" cells. Our results suggest that myostatin promoter activity is relatively higher during the G(1) phase of the cell cycle, when MyoD expression levels are maximal. However, in the reserve cells, which lack MyoD expression, a significant reduction in the myostatin promoter activity is observed. Taken together, these results suggest that the myostatin gene is a downstream target gene of MyoD. Since the myostatin gene is implicated in controlling G(1)-to-S progression of myoblasts, MyoD could be triggering myoblast withdrawal from the cell cycle by regulating myostatin gene expression.
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Sorensen A, Travers MT, Vernon RG, Price NT, Barber MC. Localization of messenger RNAs encoding enzymes associated with malonyl-CoA metabolism in mouse brain. Gene Expr Patterns 2002; 1:167-73. [PMID: 12638127 DOI: 10.1016/s1567-133x(02)00013-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Malonyl-CoA acts a fuel sensor in the pancreas, liver and muscle. Similarly, malonyl-CoA is implicated in satiety regulation in the brain. Expression of genes encoding enzymes implicated in regulation of malonyl-CoA levels was examined in murine brain. Acetyl-CoA carboxylase (ACC) alpha-isoform, fatty acid synthase and malonyl-CoA decarboxylase are highly expressed in the hippocampus, habenula nucleus, cerebral cortex and areas of the hypothalamus, whereas the ACC-beta isoform and liver-type carnitine palmitoyltransferase I (CPTI-L) are principally expressed in the choroid plexus. Thus different brain regions appear to be functionally configured primarily for either fatty acid synthesis or beta-oxidation. Localization of transcripts encoding enzymes involved in fatty acid synthesis and beta-oxidation in distinct nuclei of the hypothalamus supports a role for malonyl-CoA as a potential effector of satiety.
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Pacheco-Alvarez D, Solórzano-Vargas RS, Del Río AL. Biotin in metabolism and its relationship to human disease. Arch Med Res 2002; 33:439-47. [PMID: 12459313 DOI: 10.1016/s0188-4409(02)00399-5] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Biotin, a water-soluble vitamin, is used as cofactor of enzymes involved in carboxylation reactions. In humans, there are five biotin-dependent carboxylases: propionyl-CoA carboxylase; methylcrotonyl-CoA carboxylase; pyruvate carboxylase, and two forms of acetyl-CoA carboxylase. These enzymes catalyze key reactions in gluconeogenesis, fatty acid metabolism, and amino acid catabolism; thus, biotin plays an essential role in maintaining metabolic homeostasis. In recent years, biotin has been associated with several diseases in humans. Some are related to enzyme deficiencies involved in biotin metabolism. However, not all biotin-responsive disorders can be explained based on the classical role of the vitamin in cell metabolism. Several groups have suggested that biotin may be involved in regulating transcription or protein expression of different proteins. Biotinylation of histones and triggering of transduction signaling cascades have been suggested as underlying mechanisms behind these non-classical biotin-deficiency manifestation in humans.
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Affiliation(s)
- Diana Pacheco-Alvarez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas (IIBM), Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico
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Metzler DE, Metzler CM, Sauke DJ. Specific Aspects of Lipid Metabolism. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50024-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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