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L-Carnitine in Drosophila: A Review. Antioxidants (Basel) 2020; 9:antiox9121310. [PMID: 33371457 PMCID: PMC7767417 DOI: 10.3390/antiox9121310] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 12/12/2022] Open
Abstract
L-Carnitine is an amino acid derivative that plays a key role in the metabolism of fatty acids, including the shuttling of long-chain fatty acyl CoA to fuel mitochondrial β-oxidation. In addition, L-carnitine reduces oxidative damage and plays an essential role in the maintenance of cellular energy homeostasis. L-carnitine also plays an essential role in the control of cerebral functions, and the aberrant regulation of genes involved in carnitine biosynthesis and mitochondrial carnitine transport in Drosophila models has been linked to neurodegeneration. Drosophila models of neurodegenerative diseases provide a powerful platform to both unravel the molecular pathways that contribute to neurodegeneration and identify potential therapeutic targets. Drosophila can biosynthesize L-carnitine, and its carnitine transport system is similar to the human transport system; moreover, evidence from a defective Drosophila mutant for one of the carnitine shuttle genes supports the hypothesis of the occurrence of β-oxidation in glial cells. Hence, Drosophila models could advance the understanding of the links between L-carnitine and the development of neurodegenerative disorders. This review summarizes the current knowledge on L-carnitine in Drosophila and discusses the role of the L-carnitine pathway in fly models of neurodegeneration.
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Luo JJ, Zhang Y, Sun H, Wei JT, Khalil MM, Wang YW, Dai JF, Zhang NY, Qi DS, Sun LH. The response of glandular gastric transcriptome to T-2 toxin in chicks. Food Chem Toxicol 2019; 132:110658. [PMID: 31299295 DOI: 10.1016/j.fct.2019.110658] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 06/28/2019] [Accepted: 07/01/2019] [Indexed: 02/07/2023]
Abstract
This study was conducted to determine the effect of T-2 toxin on the transcriptome of the glandular stomach in chicks using RNA-sequencing (RNA-Seq). Four groups of 1-day-old Cobb male broilers (n = 4 cages/group, 6 chicks/cage) were fed a corn-soybean-based diet (control) and control supplemented with T-2 toxin at 1.0, 3.0, and 6.0 mg/kg, respectively, for 2 weeks. The histological results showed that dietary supplementation of T-2 toxin at 3.0 and 6.0 mg/kg induced glandular gastric injury including serious inflammation, increased inflammatory cells, mucosal edema, and necrosis and desquamation of the epithelial cells in the glandular stomach of chicks. RNA-Seq analysis revealed that there were 671, 1393, and 1394 genes displayed ≥2 (P < 0.05) differential expression in the dietary supplemental T-2 toxin at 1.0, 3.0, and 6.0 mg/kg, respectively, compared with the control group. Notably, 204 differently expressed genes had shared similar changes among these three doses of T-2 toxin. GO and KEGG pathway analysis results showed that many genes involved in oxidation-reduction process, inflammation, wound healing/bleeding, and apoptosis/carcinogenesis were affected by T-2 toxin exposure. In conclusion, this study systematically elucidated toxic mechanisms of T-2 toxin on the glandular stomach, which might provide novel ideas to prevent adverse effects of T-2 toxin in chicks.
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Affiliation(s)
- Jing-Jing Luo
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Yu Zhang
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Hua Sun
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Jin-Tao Wei
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Animal Embryo Engineering and Molecular Breeding of Hubei Province, China
| | | | - You-Wei Wang
- Postgraduate School, Hubei University of Medicine, Shiyan, 442000, Hubei, China
| | - Jie-Fan Dai
- Sichuan Green Food Development Center, Chengdu, 610041, China
| | - Ni-Ya Zhang
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - De-Sheng Qi
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Lv-Hui Sun
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
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Vaz FM, van Vlies N. Dioxygenases of Carnitine Biosynthesis: 6- N-Trimethyllysine and γ-Butyrobetaine Hydroxylases. 2-OXOGLUTARATE-DEPENDENT OXYGENASES 2015. [DOI: 10.1039/9781782621959-00324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This chapter describes the state of knowledge of the two 2-oxoglutarate-dependent dioxygenases of carnitine biosynthesis: 6-N-trimethyllysine hydroxylase and γ-butyrobetaine hydroxylase. Both enzymes have been extensively investigated as carnitine plays an important role in fatty acid metabolism in animals and some other life forms. Carnitine metabolism is introduced followed by a comprehensive review of the properties of the two carnitine biosynthesis dioxygenases including their purification, kinetic and biophysical characterization, regulation and roles in metabolism.
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Affiliation(s)
- Frédéric M. Vaz
- Laboratory Genetic Metabolic Diseases, Departments of Paediatrics and Clinical Chemistry, Emma Children’s Hospital, Academic Medical Center 1105 AZ Amsterdam The Netherlands
| | - Naomi van Vlies
- Laboratory Genetic Metabolic Diseases, Departments of Paediatrics and Clinical Chemistry, Emma Children’s Hospital, Academic Medical Center 1105 AZ Amsterdam The Netherlands
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Rigault C, Le Borgne F, Tazir B, Benani A, Demarquoy J. A high-fat diet increases L-carnitine synthesis through a differential maturation of the Bbox1 mRNAs. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1831:370-7. [PMID: 23127966 DOI: 10.1016/j.bbalip.2012.10.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 10/15/2012] [Accepted: 10/26/2012] [Indexed: 12/30/2022]
Abstract
l-carnitine is a key molecule in both mitochondrial and peroxisomal lipid metabolisms. l-carnitine is biosynthesized from gamma-butyrobetaine by a reaction catalyzed by the gamma-butyrobetaine hydroxylase (Bbox1). The aim of this work was to identify molecular mechanisms involved in the regulation of l-carnitine biosynthesis and availability. Using 3' RACE, we identified four alternatively polyadenylated Bbox1 mRNAs in rat liver. We utilized a combination of in vitro experiments using hybrid constructs containing the Bbox1 3' UTR and in vivo experiments on rat liver mRNAs to reveal specificities in the different Bbox1 mRNA isoforms, especially in terms of polyadenylation efficiency, mRNA stability and translation efficiency. This complex maturation process of the Bbox1 mRNAs in the liver was studied on rats fed a high-fat diet. High-fat diet selectively increased the level of three Bbox1 mRNA isoforms in rat liver and the alternative use of polyadenylation sites contributed to the global increase in Bbox1 enzymatic activity and l-carnitine levels. Our results show that the maturation of Bbox1 mRNAs is nutritionally regulated in the liver through a selective polyadenylation process to adjust l-carnitine biosynthesis to the energy supply.
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Affiliation(s)
- Caroline Rigault
- Université de Bourgogne, BioperoxIL, EA 7270, Faculté Gabriel, 6 blvd Gabriel, 21000 Dijon, France
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Ling B, Aziz C, Alcorn J. Systematic Evaluation of Key L-Carnitine Homeostasis Mechanisms during Postnatal Development in Rat. Nutr Metab (Lond) 2012; 9:66. [PMID: 22805277 PMCID: PMC3408321 DOI: 10.1186/1743-7075-9-66] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 07/17/2012] [Indexed: 01/01/2023] Open
Abstract
Background The conditionally essential nutrient, L-carnitine, plays a critical role in a number of physiological processes vital to normal neonatal growth and development. We conducted a systematic evaluation of the developmental changes in key L-carnitine homeostasis mechanisms in the postnatal rat to better understand the interrelationship between these pathways and their correlation to ontogenic changes in L-carnitine levels during postnatal development. Methods mRNA expression of heart, kidney and intestinal L-carnitine transporters, liver γ-butyrobetaine hydroxylase (Bbh) and trimethyllysine hydroxylase (Tmlh), and heart carnitine palmitoyltransferase (Cpt) were measured using quantitative RT-PCR. L-Carnitine levels were determined by HPLC-UV. Cpt and Bbh activity were measured by a spectrophotometric method and HPLC, respectively. Results Serum and heart L-carnitine levels increased with postnatal development. Increases in serum L-carnitine correlated significantly with postnatal increases in renal organic cation/carnitine transporter 2 (Octn2) expression, and was further matched by postnatal increases in intestinal Octn1 expression and hepatic γ-Bbh activity. Postnatal increases in heart L-carnitine levels were significantly correlated to postnatal increases in heart Octn2 expression. Although cardiac high energy phosphate substrate levels remained constant through postnatal development, creatine showed developmental increases with advancing neonatal age. mRNA levels of Cpt1b and Cpt2 significantly increased at postnatal day 20, which was not accompanied by a similar increase in activity. Conclusions Several L-carnitine homeostasis pathways underwent significant ontogenesis during postnatal development in the rat. This information will facilitate future studies on factors affecting the developmental maturation of L-carnitine homeostasis mechanisms and how such factors might affect growth and development.
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Affiliation(s)
- Binbing Ling
- College of Pharmacy and Nutrition, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N 5C9, Canada.
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Ling B, Aziz C, Wojnarowicz C, Olkowski A, Alcorn J. Timing and Duration of Drug Exposure Affects Outcomes of a Drug-Nutrient Interaction During Ontogeny. Pharmaceutics 2010; 2:321-338. [PMID: 27721360 PMCID: PMC3967141 DOI: 10.3390/pharmaceutics2040321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 10/05/2010] [Accepted: 10/12/2010] [Indexed: 11/16/2022] Open
Abstract
Significant drug-nutrient interactions are possible when drugs and nutrients share the same absorption and disposition mechanisms. During postnatal development, the outcomes of drug-nutrient interactions may change with postnatal age since these processes undergo ontogenesis through the postnatal period. Our study investigated the dependence of a significant drug-nutrient interaction (cefepime-carnitine) on the timing and duration of drug exposure relative to postnatal age. Rat pups were administered cefepime (5 mg/kg) twice daily subcutaneously according to different dosing schedules (postnatal day 1-4, 1-8, 8-11, 8-20, or 1-20). Cefepime significantly reduced serum and heart L-carnitine levels in postnatal day 1-4, 1-8 and 8-11 groups and caused severe degenerative changes in ventricular myocardium in these groups. Cefepime also altered the ontogeny of several key L-carnitine homeostasis pathways. The qualitative and quantitative changes in levels of hepatic γ-butyrobetaine hydroxylase mRNA and activity, hepatic trimethyllysine hydroxlase mRNA, intestinal organic cation/carnitine transporter (Octn) mRNA, and renal Octn2 mRNA depended on when during postnatal development the cefepime exposure occurred and duration of exposure. Despite lower levels of heart L-carnitine in earlier postnatal groups, levels of carnitine palmitoyltransferase mRNA and activity, heart Octn2 mRNA and ATP levels in all treatment groups remained unchanged with cefepime exposure. However, changes in other high energy phosphate substrates were noted and reductions in the phosphocreatine/ATP ratio were found in rat pups with normal serum L-carnitine levels. In summary, our data suggest a significant drug-nutrient transport interaction in developing neonates, the nature of which depends on the timing and duration of exposure relative to postnatal age.
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Affiliation(s)
- Binbing Ling
- College of Pharmacy and Nutrition, University of Saskatchewan, 110 Science Place, Saskatoon, S7N5C9, Canada
| | - Caroline Aziz
- Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK, S7N 5B3, Canada
| | - Chris Wojnarowicz
- Department of Veterinary Pathology, Prairie Diagnostic Services, 52 Campus Drive, University of Saskatchewan, Saskatoon, SK, S7N 5B4, Canada
| | - Andrew Olkowski
- Department of Animal and Poultry Science, University of Saskatchewan, 51 Campus Drive Saskatoon, SK, S7N 5A8, Canada
| | - Jane Alcorn
- College of Pharmacy and Nutrition, University of Saskatchewan, 110 Science Place, Saskatoon, S7N5C9, Canada.
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Activities of γ-butyrobetaine dioxygenase and concentrations of carnitine in tissues of pigs. Comp Biochem Physiol A Mol Integr Physiol 2009; 153:324-31. [DOI: 10.1016/j.cbpa.2009.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 03/07/2009] [Accepted: 03/08/2009] [Indexed: 11/19/2022]
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García-Delgado M, Peral MJ, Durán JM, García-Miranda P, Calonge ML, Ilundáin AA. Ontogeny of Na+/l-carnitine transporter and of γ-trimethylaminobutyraldehyde dehydrogenase and γ-butyrobetaine hydroxylase genes expression in rat kidney. Mech Ageing Dev 2009; 130:227-33. [DOI: 10.1016/j.mad.2008.12.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 11/20/2008] [Accepted: 12/13/2008] [Indexed: 11/26/2022]
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Rigault C, Bernard A, Georges B, Kandel A, Pfützner E, Le Borgne F, Demarquoy J. Extracellular ATP increases L-carnitine transport and content in C2C12 cells. Pharmacology 2008; 81:246-50. [PMID: 18230920 DOI: 10.1159/000114449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Accepted: 10/30/2007] [Indexed: 11/19/2022]
Abstract
Extracellular ATP regulates cell proliferation, muscle contraction and myoblast differentiation. ATP present in the muscle interstitium can be released from contracting skeletal muscle cells. L-Carnitine is a key element in muscle cell metabolism, as it serves as a carrier for fatty acid through mitochondrial membranes, controlling oxidation and energy production. Treatment of C2C12 cells with 1 mmol/l of ATP induced a marked increase in L-carnitine uptake that was associated with an increase in L-carnitine content in these cells. These effects were found to be dependent on the density of the cultured cells and on the dose of ATP. The use of specific inhibitors of P2X and P2Y receptors abolished the effect of ATP on L-carnitine metabolism. As ATP can be released from stressed or exercising cells, it can be hypothesized that ATP acts as a messenger in the muscle. ATP will be released to recruit the next cells and increase their metabolism.
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Affiliation(s)
- Caroline Rigault
- INSERM U866, Laboratoire de Biochimie Métabolique et Nutritionnelle, Faculté Gabriel, Université de Bourgogne, Dijon, France
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Carlson DB, Woodworth JC, Drackley JK. Effect of l-Carnitine Infusion and Feed Restriction on Carnitine Status in Lactating Holstein Cows. J Dairy Sci 2007; 90:2367-76. [PMID: 17430940 DOI: 10.3168/jds.2006-605] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Previously we determined that abomasal infusion of L-carnitine increased in vitro hepatic fatty acid oxidation, decreased liver lipid accumulation, and supported higher fat-corrected milk yield in feed-restricted lactating cows. The objectives of this study were to examine the effects of supplemental L-carnitine and amount of feed intake on free carnitine and carnitine ester concentrations in liver, muscle, milk, and plasma of lactating dairy cows. Eight lactating Holstein cows (132 +/- 36 d in milk) were used in a replicated 4 x 4 Latin square design with 14-d periods to test factorial combinations of water or L-carnitine infusion (20 g/d; d 5 to 14) and ad libitum or restricted (50% of previous 5-d intake; d 10 to 14) dry matter intake. Plasma was obtained 3 times daily on d 4, 8, and 12; milk samples were collected on d 8, 9, 13, and 14. Liver and muscle were biopsied on d 14 of each period. Free carnitine, short-chain acylcarnitine, and long-chain acylcarnitine concentrations were determined using a radioenzymatic assay coupled with ion exchange chromatography. Abomasal L-carnitine infusion increased total carnitine in plasma on d 8 and d 12. All liver carnitine fractions were increased by carnitine infusion. Feed restriction elevated concentrations of free carnitine, long-chain acylcarnitine, and total carnitine in liver tissue from carnitine-infused cows but not in those infused with water. In muscle, acid-soluble carnitine, long-chain acylcarnitine, and total carnitine concentrations were increased by carnitine infusion and feed restriction without significant interaction. Feed restriction increased free carnitine concentrations in muscle from water-infused cows but not in carnitine-infused cows. Carnitine infusion increased the concentration of each milk carnitine fraction as well as milk carnitine output on d 8 to 9. On d 13 to 14, all carnitine fractions except short-chain acylcarnitine were increased in milk from water-infused, feed-restricted cows, whereas all fractions were increased in carnitine-infused, feed-restricted cows. Carnitine infusion increased total carnitine in plasma, liver, muscle, and milk during feed restriction, whereas feed restriction alone increased carnitine concentrations in muscle and milk but not in liver. Liver carnitine concentrations might limit hepatic fatty acid oxidation capacity in dairy cows during the periparturient period; therefore, supplemental L-carnitine might decrease liver lipid accumulation in periparturient cows.
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Affiliation(s)
- D B Carlson
- Department of Animal Sciences, University of Illinois, Urbana 61801, USA
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Rigault C, Le Borgne F, Georges B, Demarquoy J. Ghrelin reduces hepatic mitochondrial fatty acid beta oxidation. J Endocrinol Invest 2007; 30:RC4-8. [PMID: 17556859 DOI: 10.1007/bf03346290] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ghrelin is a 28-amino-acid peptide secreted during starvation by gastric cells. Ghrelin physiologically induces food intake and seems to alter lipid and glucid metabolism in several tissues such as adipose tissue and liver. Liver has a key position in lipid metabolism as it allows the metabolic orientation of fatty acids between oxidation and esterification. We investigated the effects of peripheral ghrelin administration on 2 crucial parameters of fatty acid oxidation: the levocarnitine (L-carnitine)-dependent entry of the fatty acids in the mitochondria and the mitochondrial fatty acid oxidation. Ghrelin was either given to rats prior to the hepatocyte preparation and culture or used to treat hepatocytes prepared from control animals. Direct incubation of ghrelin to raw hepatocytes did not induce any change in the studied parameters. In hepatocytes prepared from 3 nmol ghrelin-treated rats, a 44% reduction of the mitochondrial fatty acid oxidation while no alteration of the L-carnitine-related parameters were observed. These results suggested (a) that ghrelin has no direct effect on liver, and (b) that when administrated to a whole organism, ghrelin may alter the lipid metabolism and the energy balance through a marked decrease in liver fatty acid oxidation.
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Affiliation(s)
- C Rigault
- INSERM, Faculty of Sciences Gabriel, Metabolic and Nutritional Biochemics (LBMN), University of Burgundy, Dijon, France
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Rigault C, Le Borgne F, Demarquoy J. Genomic structure, alternative maturation and tissue expression of the human BBOX1 gene. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:1469-81. [PMID: 17110165 DOI: 10.1016/j.bbalip.2006.09.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2006] [Revised: 09/29/2006] [Accepted: 09/29/2006] [Indexed: 02/07/2023]
Abstract
Gamma-butyrobetaine hydroxylase (BBOX1) is the enzyme responsible for the biosynthesis of l-carnitine, a key molecule of fatty acid metabolism. This cytosolic dimeric protein belongs to the dioxygenase family. In human, enzyme activity has been detected in kidney, liver and brain. The human gene encoding gamma-butyrobetaine hydroxylase is located on chromosome 11. Although the protein structure and activity have been extensively described, little information is available concerning BBOX1 structure and expression. In this study, the organization of the human gene was determined. The structure and functions of the 5'- and 3'-untranslated regions of the human BBOX1 mRNA were characterized in kidney, liver and brain. Our experiments revealed that the transcription initiation of the human BBOX1 gene might occur at 3 different exons, and that the expression level of each type of transcript is organ-specific. We showed that the use of 3 different promoters is responsible for the 5'-end heterogeneity. Investigations on BBOX1 mRNA maturation highlighted an alternative polyadenylation mechanism that generates two 3'-untranslated regions differing by their length. This alternative polyadenylation exhibited a tissue specificity.
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Affiliation(s)
- Caroline Rigault
- Inserm - CRI-Dijon, University of Dijon, UFR Sciences Vie, 6 Blvd. Gabriel, 21000 Dijon, France
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Clifton IJ, McDonough MA, Ehrismann D, Kershaw NJ, Granatino N, Schofield CJ. Structural studies on 2-oxoglutarate oxygenases and related double-stranded β-helix fold proteins. J Inorg Biochem 2006; 100:644-69. [PMID: 16513174 DOI: 10.1016/j.jinorgbio.2006.01.024] [Citation(s) in RCA: 335] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 01/12/2006] [Accepted: 01/12/2006] [Indexed: 01/09/2023]
Abstract
Mononuclear non-heme ferrous iron dependent oxygenases and oxidases constitute an extended enzyme family that catalyze a wide range of oxidation reactions. The largest known sub-group employs 2-oxoglutarate as a cosubstrate and catalysis by these and closely related enzymes is proposed to proceed via a ferryl intermediate coordinated to the active site via a conserved HXD/E...H motif. Crystallographic studies on the 2-oxoglutarate oxygenases and related enzymes have revealed a common double-stranded beta-helix core fold that supports the residues coordinating the iron. This fold is common to proteins of the cupin and the JmjC transcription factor families. The crystallographic studies on 2-oxoglutarate oxygenases and closely related enzymes are reviewed and compared with other metallo-enzymes/related proteins containing a double-stranded beta-helix fold. Proposals regarding the suitability of the active sites and folds of the 2-oxoglutarate oxygenases to catalyze reactions involving reactive oxidizing species are described.
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Affiliation(s)
- Ian J Clifton
- The Oxford Centre for Molecular Sciences and the Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, Oxon OX1 3TA, UK
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García-Miranda P, Durán JM, Peral MJ, Ilundáin AA. Developmental maturation and segmental distribution of rat small intestinal L-carnitine uptake. J Membr Biol 2006; 206:9-16. [PMID: 16440177 DOI: 10.1007/s00232-005-0769-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Indexed: 01/20/2023]
Abstract
Oral L-carnitine supplementation is commonly used in sports nutrition and in medicine; however, there is controversy regarding the mechanisms that mediate intestinal L-carnitine transport. We have previously reported that the Na(+)/L-carnitine transporter OCTN2 is present in the small intestinal apical membrane. Herein we aimed to find out if this step of intestinal L-carnitine absorption is ontogenically regulated, and if so, to determine the molecular mechanism(s) involved. L-[(3)H]-Carnitine uptake was measured in the jejunum and ileum of fetuses (E17 and E21), newborn (1 day-old), suckling (15 day-old), weaning (1 month-old) and adult (2 and 6 month-old) Wistar rats. Both, Na(+) -dependent and Na(+) -independent L-carnitine uptake rates, normalized to intestinal weight, significantly increased during the late gestation period, and then declined during the suckling period. After weaning, the rate of Na(+) -dependent L-carnitine uptake is no longer measurable. In E21- fetuses and newborn rats, L-carnitine uptake was higher in the ileum than in the jejunum. The decline in Na(+) -dependent L-carnitine uptake with maturation was mediated via a decrease in the V(max) of the uptake process with no change in its apparent K(m). Semi-quantitative RT-PCR assays showed that OCTN2 mRNA levels were significantly higher in E21-fetuses and newborn rats compared to suckling rats, which were in turn significantly higher than that in adult rats. Neither retardation of weaning nor L-carnitine supplementation prevented the down-regulation of Na(+)/L-carnitine transport activity. The results demonstrate for the first time that intestinal Na(+) -dependent L-carnitine uptake activity is under genetic regulation at the transcriptional level.
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Affiliation(s)
- P García-Miranda
- Depto. Fisiología y Zoología, Facultad de Farmacia, Universidad de Sevilla, Spain
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Davis AT, Monroe TJ. Carnitine deficiency and supplementation do not affect the gene expression of carnitine biosynthetic enzymes in rats. J Nutr 2005; 135:761-4. [PMID: 15795431 DOI: 10.1093/jn/135.4.761] [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] [Indexed: 01/10/2023] Open
Abstract
Starved male weanling rats supplemented with 20 mmol/L pivalate in their drinking water exhibit significantly depressed concentrations of carnitine in tissues and plasma. In addition, pivalate supplementation has been linked with increased renal and hepatic trimethyllysine hydroxylase (TMLH) activity, whereas carnitine supplementation has been associated with significantly decreased hepatic gamma-butyrobetaine hydroxylase (BBH) activity. The purpose of this study was to determine whether pivalate or carnitine supplementation affects the activity and genetic expression of 2 enzymes of carnitine (Cn) biosynthesis, TMLH and BBH, expressed as mRNA abundance, relative to the abundance of beta-actin mRNA. Male weanling rats were administered the control treatment (C; n = 6), the pivalate treatment (P; n = 7), or the pivalate treatment plus supplemental dietary carnitine (P+Cn; n = 7). Rats in group P had elevated renal TMLH activity, relative to the other groups (P < 0.05). The groups did not differ in the abundance of renal or hepatic TMLH or BBH mRNA. A previously unreported finding was the quantifiable level of renal BBH mRNA, which was verified by direct sequencing of the BBH cDNA product amplified from kidney RNA. The groups did not differ in renal BBH mRNA abundance and renal BBH enzyme activity was not detected. Thus, the alterations in enzyme activities in the pivalate-treated rats are not regulated at the transcriptional level, and are apparently related to post-transcriptional effects on the enzymes themselves.
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Affiliation(s)
- Alan T Davis
- Department of Surgery, Michigan State University, Grand Rapids, MI, USA.
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Demarquoy J, Georges B, Rigault C, Royer MC, Clairet A, Soty M, Lekounoungou S, Le Borgne F. Radioisotopic determination of l-carnitine content in foods commonly eaten in Western countries. Food Chem 2004. [DOI: 10.1016/j.foodchem.2003.09.023] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Swiegers JH, Vaz FM, Pretorius IS, Wanders RJA, Bauer FF. Carnitine biosynthesis in Neurospora crassa: identification of a cDNA coding for epsilon-N-trimethyllysine hydroxylase and its functional expression in Saccharomyces cerevisiae. FEMS Microbiol Lett 2002; 210:19-23. [PMID: 12023072 DOI: 10.1111/j.1574-6968.2002.tb11154.x] [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: 11/29/2022] Open
Abstract
The biosynthesis of L-carnitine in eukaryotic organisms was first elucidated in the ascomycete Neurospora crassa. The first step of the pathway is catalysed by epsilon-N-trimethyllysine hydroxylase (TMLH), which converts epsilon-N-trimethyllysine into beta-hydroxy-N-epsilon-trimethyllysine in a reaction dependent on alpha-ketoglutarate, Fe2+ and oxygen. Here we report on the cloning of the N. crassa TMLH cDNA and its functional expression in Saccharomyces cerevisiae. The TMLH cDNA contains an open reading frame of 1413 base pairs encoding a predicted polypeptide of 471 amino acids. The Michaelis-Menten constants of the heterologously expressed enzyme were determined for epsilon-N-trimethyllysine, alpha-ketoglutarate, Fe2+ and correspond to 0.33 mM, 133 microM and 46 microM, respectively.
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Affiliation(s)
- Jan H Swiegers
- Institute for Wine Biotechnology, Department of Viticulture and Oenology, Stellenbosch University, 7600, South Africa
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Abstract
Carnitine is indispensable for energy metabolism, since it enables activated fatty acids to enter the mitochondria, where they are broken down via beta-oxidation. Carnitine is probably present in all animal species, and in numerous micro-organisms and plants. In mammals, carnitine homoeostasis is maintained by endogenous synthesis, absorption from dietary sources and efficient tubular reabsorption by the kidney. This review aims to cover the current knowledge of the enzymological, molecular, metabolic and regulatory aspects of mammalian carnitine biosynthesis, with an emphasis on the human and rat.
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Abstract
Carnitine is indispensable for energy metabolism, since it enables activated fatty acids to enter the mitochondria, where they are broken down via beta-oxidation. Carnitine is probably present in all animal species, and in numerous micro-organisms and plants. In mammals, carnitine homoeostasis is maintained by endogenous synthesis, absorption from dietary sources and efficient tubular reabsorption by the kidney. This review aims to cover the current knowledge of the enzymological, molecular, metabolic and regulatory aspects of mammalian carnitine biosynthesis, with an emphasis on the human and rat.
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Affiliation(s)
- Frédéric M Vaz
- Laboratory for Genetic Metabolic Diseases, Departments of Clinical Chemistry and Paediatrics, Emma Children's Hospital, Academic Medical Centre, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands.
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