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Moon SH, Liu X, Jenkins CM, Dilthey BG, Patti GJ, Gross RW. Etomoxir-carnitine, a novel pharmaco-metabolite of etomoxir, inhibits phospholipases A 2 and mitochondrial respiration. J Lipid Res 2024; 65:100611. [PMID: 39094773 PMCID: PMC11402452 DOI: 10.1016/j.jlr.2024.100611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 07/23/2024] [Accepted: 07/24/2024] [Indexed: 08/04/2024] Open
Abstract
Mitochondrial fatty acid oxidation serves as an essential process for cellular survival, differentiation, proliferation, and energy metabolism. Numerous studies have utilized etomoxir (ETO) for the irreversible inhibition of carnitine palmitoylcarnitine transferase 1 (CPT1), which catalyzes the rate-limiting step for mitochondrial long-chain fatty acid β-oxidation to examine the bioenergetic roles of mitochondrial fatty acid metabolism in many tissues in multiple diverse disease states. Herein, we demonstrate that intact mitochondria robustly metabolize ETO to etomoxir-carnitine (ETO-carnitine) prior to nearly complete ETO-mediated inhibition of CPT1. The novel pharmaco-metabolite, ETO-carnitine, was conclusively identified by accurate mass, fragmentation patterns, and isotopic fine structure. On the basis of these data, ETO-carnitine was successfully differentiated from isobaric structures (e.g., 3-hydroxy-C18:0 carnitine and 3-hydroxy-C18:1 carnitine). Mechanistically, generation of ETO-carnitine from mitochondria required exogenous Mg2+, ATP or ADP, CoASH, and L-carnitine, indicating that thioesterification by long-chain acyl-CoA synthetase to form ETO-CoA precedes its conversion to ETO-carnitine by CPT1. CPT1-dependent generation of ETO-carnitine was substantiated by an orthogonal approach using ST1326 (a CPT1 inhibitor), which effectively inhibits mitochondrial ETO-carnitine production. Surprisingly, purified ETO-carnitine potently inhibited calcium-independent PLA2γ and PLA2β as well as mitochondrial respiration independent of CPT1. Robust production and release of ETO-carnitine from HepG2 cells incubated in the presence of ETO was also demonstrated. Collectively, this study identifies the chemical mechanism for the biosynthesis of a novel pharmaco-metabolite of ETO, ETO-carnitine, that is generated by CPT1 in mitochondria and likely impacts multiple downstream (non-CPT1 related) enzymes and processes in multiple subcellular compartments.
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Affiliation(s)
- Sung Ho Moon
- Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Xinping Liu
- Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Christopher M Jenkins
- Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Beverly Gibson Dilthey
- Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Gary J Patti
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA; Department of Chemistry, Washington University, Saint Louis, MO, USA; Siteman Cancer Center, Washington University in St. Louis, Saint Louis, MO, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, Saint Louis, MO, USA
| | - Richard W Gross
- Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA; Department of Chemistry, Washington University, Saint Louis, MO, USA; Department of Developmental Biology, Washington University School of Medicine, Saint Louis, MO, USA; Center for Cardiovascular Research, Washington University School of Medicine, Saint Louis, MO, USA.
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Zagmutt S, Mera P, González-García I, Ibeas K, Romero MDM, Obri A, Martin B, Esteve-Codina A, Soler-Vázquez MC, Bastias-Pérez M, Cañes L, Augé E, Pelegri C, Vilaplana J, Ariza X, García J, Martinez-González J, Casals N, López M, Palmiter R, Sanz E, Quintana A, Herrero L, Serra D. CPT1A in AgRP neurons is required for sex-dependent regulation of feeding and thirst. Biol Sex Differ 2023; 14:14. [PMID: 36966335 PMCID: PMC10040140 DOI: 10.1186/s13293-023-00498-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 03/10/2023] [Indexed: 03/27/2023] Open
Abstract
BACKGROUND Fatty acid metabolism in the hypothalamus has an important role in food intake, but its specific role in AgRP neurons is poorly understood. Here, we examined whether carnitinea palmitoyltransferase 1A (CPT1A), a key enzyme in mitochondrial fatty acid oxidation, affects energy balance. METHODS To obtain Cpt1aKO mice and their control littermates, Cpt1a(flox/flox) mice were crossed with tamoxifen-inducible AgRPCreERT2 mice. Food intake and body weight were analyzed weekly in both males and females. At 12 weeks of age, metabolic flexibility was determined by ghrelin-induced food intake and fasting-refeeding satiety tests. Energy expenditure was analyzed by calorimetric system and thermogenic activity of brown adipose tissue. To study fluid balance the analysis of urine and water intake volumes; osmolality of urine and plasma; as well as serum levels of angiotensin and components of RAAS (renin-angiotensin-aldosterone system) were measured. At the central level, changes in AgRP neurons were determined by: (1) analyzing specific AgRP gene expression in RiboTag-Cpt1aKO mice obtained by crossing Cpt1aKO mice with RiboTag mice; (2) measuring presynaptic terminal formation in the AgRP neurons with the injection of the AAV1-EF1a-DIO-synaptophysin-GFP in the arcuate nucleus of the hypothalamus; (3) analyzing AgRP neuronal viability and spine formations by the injection AAV9-EF1a-DIO-mCherry in the arcuate nucleus of the hypothalamus; (4) analyzing in situ the specific AgRP mitochondria in the ZsGreen-Cpt1aKO obtained by breeding ZsGreen mice with Cpt1aKO mice. Two-way ANOVA analyses were performed to determine the contributions of the effect of lack of CPT1A in AgRP neurons in the sex. RESULTS Changes in food intake were just seen in male Cpt1aKO mice while only female Cpt1aKO mice increased energy expenditure. The lack of Cpt1a in the AgRP neurons enhanced brown adipose tissue activity, mainly in females, and induced a substantial reduction in fat deposits and body weight. Strikingly, both male and female Cpt1aKO mice showed polydipsia and polyuria, with more reduced serum vasopressin levels in females and without osmolality alterations, indicating a direct involvement of Cpt1a in AgRP neurons in fluid balance. AgRP neurons from Cpt1aKO mice showed a sex-dependent gene expression pattern, reduced mitochondria and decreased presynaptic innervation to the paraventricular nucleus, without neuronal viability alterations. CONCLUSIONS Our results highlight that fatty acid metabolism and CPT1A in AgRP neurons show marked sex differences and play a relevant role in the neuronal processes necessary for the maintenance of whole-body fluid and energy balance.
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Affiliation(s)
- Sebastián Zagmutt
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Paula Mera
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Ismael González-García
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
| | - Kevin Ibeas
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - María Del Mar Romero
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Arnaud Obri
- Neuronal Control of Metabolism Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Beatriz Martin
- CNAG-CRG, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 08028, Barcelona, Spain
| | - Anna Esteve-Codina
- CNAG-CRG, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 08028, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - M Carmen Soler-Vázquez
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Marianela Bastias-Pérez
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Laia Cañes
- Instituto de Investigaciones Biomédicas de Barcelona (IIBB-CSIC), Barcelona, Spain
- CIBER de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
- Instituto de Investigación Biomédica Sant Pau (IIB-Sant Pau), Barcelona, Spain
| | - Elisabeth Augé
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Carme Pelegri
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
- Institute of Neurosciences of the Universitat de Barcelona, Barcelona, Spain
| | - Jordi Vilaplana
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
- Institute of Neurosciences of the Universitat de Barcelona, Barcelona, Spain
| | - Xavier Ariza
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
- Department of Inorganic & Organic Chemistry, Faculty of Chemistry, Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Jordi García
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
- Department of Inorganic & Organic Chemistry, Faculty of Chemistry, Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - José Martinez-González
- Instituto de Investigaciones Biomédicas de Barcelona (IIBB-CSIC), Barcelona, Spain
- CIBER de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
- Instituto de Investigación Biomédica Sant Pau (IIB-Sant Pau), Barcelona, Spain
| | - Núria Casals
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
- Department of Basic Sciences, Faculty of Medicine & Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain
| | - Miguel López
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
| | - Richard Palmiter
- Department of Biochemistry, Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
| | - Elisenda Sanz
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Albert Quintana
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Laura Herrero
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Dolors Serra
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Av. Joan XXIII, 27-31, 08028, Barcelona, Spain.
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain.
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain.
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Hedgehog Acyltransferase Promotes Uptake of Palmitoyl-CoA across the Endoplasmic Reticulum Membrane. Cell Rep 2020; 29:4608-4619.e4. [PMID: 31875564 PMCID: PMC6948154 DOI: 10.1016/j.celrep.2019.11.110] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 10/29/2019] [Accepted: 11/26/2019] [Indexed: 12/14/2022] Open
Abstract
Attachment of palmitate to the N terminus of Sonic hedgehog (Shh) is essential for Shh signaling. Shh palmitoylation is catalyzed on the luminal side of the endoplasmic reticulum (ER) by Hedgehog acyltransferase (Hhat), an ER-resident enzyme. Palmitoyl-coenzyme A (CoA), the palmitate donor, is produced in the cytosol and is not permeable across membrane bilayers. It is not known how palmitoyl-CoA crosses the ER membrane to access the active site of Hhat. Here, we use fluorescent and radiolabeled palmitoyl-CoA probes to demonstrate that Hhat promotes the uptake of palmitoyl-CoA across the ER membrane in microsomes and semi-intact cells. Reconstitution of purified Hhat into liposomes provided further evidence that palmitoyl-CoA uptake activity is an intrinsic property of Hhat. Palmitoyl-CoA uptake was regulated by and could be uncoupled from Hhat enzymatic activity, implying that Hhat serves a dual function as a palmitoyl acyltransferase and a conduit to supply palmitoyl-CoA to the luminal side of the ER. Palmitoylation of hedgehog proteins by Hedgehog acyltransferase (Hhat) occurs on the luminal side of the ER. However, the palmitoyl-CoA donor for the reaction is membrane impermeable. Asciolla and Resh show that Hhat serves a dual function as both an acyltransferase and a transporter that promotes palmitoyl-CoA uptake across the ER membrane.
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Melone MAB, Valentino A, Margarucci S, Galderisi U, Giordano A, Peluso G. The carnitine system and cancer metabolic plasticity. Cell Death Dis 2018; 9:228. [PMID: 29445084 PMCID: PMC5833840 DOI: 10.1038/s41419-018-0313-7] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/09/2018] [Accepted: 01/11/2018] [Indexed: 12/11/2022]
Abstract
Metabolic flexibility describes the ability of cells to respond or adapt its metabolism to support and enable rapid proliferation, continuous growth, and survival in hostile conditions. This dynamic character of the cellular metabolic network appears enhanced in cancer cells, in order to increase the adaptive phenotype and to maintain both viability and uncontrolled proliferation. Cancer cells can reprogram their metabolism to satisfy the energy as well as the biosynthetic intermediate request and to preserve their integrity from the harsh and hypoxic environment. Although several studies now recognize these reprogrammed activities as hallmarks of cancer, it remains unclear which are the pathways involved in regulating metabolic plasticity. Recent findings have suggested that carnitine system (CS) could be considered as a gridlock to finely trigger the metabolic flexibility of cancer cells. Indeed, the components of this system are involved in the bi-directional transport of acyl moieties from cytosol to mitochondria and vice versa, thus playing a fundamental role in tuning the switch between the glucose and fatty acid metabolism. Therefore, the CS regulation, at both enzymatic and epigenetic levels, plays a pivotal role in tumors, suggesting new druggable pathways for prevention and treatment of human cancer.
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Affiliation(s)
- Mariarosa Anna Beatrice Melone
- Department of Medical, Surgical, Neurological, Metabolic Sciences, and Aging, 2nd Division of Neurology, Center for Rare Diseases and InterUniversity Center for Research in Neurosciences, University of Campania "Luigi Vanvitelli", Naples, Italy
- Department of Biology, Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA
| | - Anna Valentino
- Department of Medical, Surgical, Neurological, Metabolic Sciences, and Aging, 2nd Division of Neurology, Center for Rare Diseases and InterUniversity Center for Research in Neurosciences, University of Campania "Luigi Vanvitelli", Naples, Italy
- Institute of Agro-Environmental and Forest Biology, National Research Council, IBAF-CNR, Naples, Italy
| | | | - Umberto Galderisi
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Antonio Giordano
- Department of Biology, Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA.
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy.
| | - Gianfranco Peluso
- Institute of Agro-Environmental and Forest Biology, National Research Council, IBAF-CNR, Naples, Italy.
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Alemán G, Ortiz V, Contreras AV, Quiroz G, Ordaz-Nava G, Langley E, Torres N, Tovar AR. Hepatic amino acid-degrading enzyme expression is downregulated by natural and synthetic ligands of PPARα in rats. J Nutr 2013; 143:1211-8. [PMID: 23761645 DOI: 10.3945/jn.113.176354] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Body nitrogen retention is dependent on the amount of dietary protein consumed, as well as the fat and carbohydrate content in the diet, due to the modulation of amino acid oxidation. PPARα is a transcription factor involved in the upregulation of the expression of enzymes of fatty acid oxidation. However, the role of putative PPARα response elements (PPREs) in the promoter of several amino acid-degrading enzymes (AADEs) is not known. The aim of this work was to study the effect of the synthetic ligand Wy 14643 and the natural ligands palmitate, oleate, and linoleate in rats fed graded concentrations of dietary protein (6, 20, or 50 g/100 g of total diet) on the expression of the AADEs histidase, serine dehydratase, and tyrosine aminotransferase. Thus, we fed male Wistar rats diets containing 6, 20, or 50% casein for 10 d. The results showed that addition of Wy 14643 to the diet significantly reduced the expression of the AADEs. Furthermore, the incubation of hepatocytes with natural ligands of PPARα or feeding rats with diets containing soybean oil, safflower oil, lard, or coconut oil as sources of dietary fat significantly repressed the expression of the AADEs. Gene reporter assays and mobility shift assays demonstrated that the PPRE located at -482 bp of the histidase gene actively bound PPARα in rat hepatocytes. These data indicate that PPARα ligands may reduce amino acid catabolism in rats.
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Affiliation(s)
- Gabriela Alemán
- Departamento de Fisiología de la Nutrición, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico, DF, Mexico
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Chambers KT, Chen Z, Crawford PA, Fu X, Burgess SC, Lai L, Leone TC, Kelly DP, Finck BN. Liver-specific PGC-1beta deficiency leads to impaired mitochondrial function and lipogenic response to fasting-refeeding. PLoS One 2012; 7:e52645. [PMID: 23285128 PMCID: PMC3532159 DOI: 10.1371/journal.pone.0052645] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 11/19/2012] [Indexed: 11/18/2022] Open
Abstract
PGC-1β plays pleiotropic roles in regulating intermediary metabolism and has been shown to regulate both catabolic and anabolic processes in liver. We sought to evaluate the effects of PGC-1β on liver energy metabolism by generating mice with postnatal, liver-specific deletion of PGC-1β (LS-PGC-1β(-/-) mice). LS-PGC-1β(-/-) mice were outwardly normal, but exhibited a significant increase in hepatic triglyceride content at 6 weeks of age. Hepatic steatosis was due, at least in part, to impaired capacity for fatty acid oxidation and marked mitochondrial dysfunction. Mitochondrial DNA content and the expression of genes encoding multiple steps in mitochondrial fatty acid oxidation and oxidative phosphorylation pathways were significantly diminished in LS-PGC-1β(-/-) mice. Liquid chromatography mass spectrometry-based analyses also revealed that acetylcarnitine and butyrylcarnitine levels were depleted whereas palmitoylcarnitine content was increased in LS-PGC-1β(-/-) liver, which is consistent with attenuated rates of fatty acid oxidation. Interestingly, loss of PGC-1β also significantly impaired inducible expression of glycolytic and lipogenic enzymes that occurs with high carbohydrate diet refeeding after a prolonged fast. These results suggest that PGC-1β plays dual roles in regulating hepatic fatty acid metabolism by controlling the expression of programs of genes involved in both fatty acid oxidation and de novo fatty acid synthesis.
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Affiliation(s)
- Kari T. Chambers
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Zhouji Chen
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Peter A. Crawford
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Xiaorong Fu
- Advanced Imaging Research Center and Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Shawn C. Burgess
- Advanced Imaging Research Center and Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Ling Lai
- The Sanford-Burnham Medical Research Institute at Lake Nona, Orlando, Florida, United States of America
| | - Teresa C. Leone
- The Sanford-Burnham Medical Research Institute at Lake Nona, Orlando, Florida, United States of America
| | - Daniel P. Kelly
- The Sanford-Burnham Medical Research Institute at Lake Nona, Orlando, Florida, United States of America
| | - Brian N. Finck
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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Morán-Ramos S, Avila-Nava A, Tovar AR, Pedraza-Chaverri J, López-Romero P, Torres N. Opuntia ficus indica (nopal) attenuates hepatic steatosis and oxidative stress in obese Zucker (fa/fa) rats. J Nutr 2012; 142:1956-63. [PMID: 23014486 DOI: 10.3945/jn.112.165563] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is associated with multiple factors such as obesity, insulin resistance, and oxidative stress. Nopal, a cactus plant widely consumed in the Mexican diet, is considered a functional food because of its antioxidant activity and ability to improve biomarkers of metabolic syndrome. The aim of this study was to assess the effect of nopal consumption on the development of hepatic steatosis and hepatic oxidative stress and on the regulation of genes involved in hepatic lipid metabolism. Obese Zucker (fa/fa) rats were fed a control diet or a diet containing 4% nopal for 7 wk. Rats fed the nopal-containing diet had ∼50% lower hepatic TG than the control group as well as a reduction in hepatomegaly and biomarkers of hepatocyte injury such as alanine and aspartate aminotransferases. Attenuation of hepatic steatosis by nopal consumption was accompanied by a higher serum concentration of adiponectin and a greater abundance of mRNA for genes involved in lipid oxidation and lipid export and production of carnitine palmitoyltransferase-1 and microsomal TG transfer proteins in liver. Hepatic reactive oxygen species and lipid peroxidation biomarkers were significantly lower in rats fed nopal compared with the control rats. Furthermore, rats fed the nopal diet had a lower postprandial serum insulin concentration and a greater liver phosphorylated protein kinase B (pAKT):AKT ratio in the postprandial state. This study suggests that nopal consumption attenuates hepatic steatosis by increasing fatty acid oxidation and VLDL synthesis, decreasing oxidative stress, and improving liver insulin signaling in obese Zucker (fa/fa) rats.
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Affiliation(s)
- Sofía Morán-Ramos
- Departamento de Fisiología de la Nutrición, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
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Rufer AC, Thoma R, Hennig M. Structural insight into function and regulation of carnitine palmitoyltransferase. Cell Mol Life Sci 2009; 66:2489-501. [PMID: 19430727 PMCID: PMC11115844 DOI: 10.1007/s00018-009-0035-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Revised: 03/18/2009] [Accepted: 04/09/2009] [Indexed: 01/07/2023]
Abstract
The control of fatty acid translocation across the mitochondrial membrane is mediated by the carnitine palmitoyltransferase (CPT) system. Modulation of its functionality has simultaneous effects on fatty acid and glucose metabolism. This encourages use of the CPT system as drug target for reduction of gluconeogenesis and restoration of lipid homeostasis, which are beneficial in the treatment of type 2 diabetes mellitus and obesity. Recently, crystal structures of CPT-2 were determined in uninhibited forms and in complexes with inhibitory substrate-analogs with anti-diabetic properties in animal models and in clinical studies. The CPT-2 crystal structures have advanced understanding of CPT structure-function relationships and will facilitate discovery of novel inhibitors by structure-based drug design. However, a number of unresolved questions regarding the biochemistry and pharmacology of CPT enzymes remain and are addressed in this review.
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Affiliation(s)
- Arne C. Rufer
- F. Hoffmann-La Roche AG, Pharma Research Discovery Technologies, 4070 Basel, Switzerland
| | - Ralf Thoma
- F. Hoffmann-La Roche AG, Pharma Research Discovery Technologies, 4070 Basel, Switzerland
| | - Michael Hennig
- F. Hoffmann-La Roche AG, Pharma Research Discovery Technologies, 4070 Basel, Switzerland
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9
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Dietary soy protein isolate attenuates metabolic syndrome in rats via effects on PPAR, LXR, and SREBP signaling. J Nutr 2009; 139:1431-8. [PMID: 19515742 DOI: 10.3945/jn.109.107029] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
To determine the effects of feeding soy or isoflavones on lipid homeostasis in early development, weanling rats were fed AIN-93G diets made with casein, soy protein isolate (SPI+), isoflavone-reduced SPI+ (SPI-), or casein supplemented with genistein or daidzein for 14 d. PPARalpha-regulated genes and proteins involved in fatty acid degradation were upregulated by SPI+ (P < 0.05) accompanied by increased promoter binding and expression of PPARalpha mRNA (P < 0.05). Feeding SPI- or pure isoflavones did not alter PPARalpha-regulated pathways. SPI+ feeding had similar effects on PPARgamma signaling. SPI+, SPI-, and casein plus isoflavones all increased liver X-receptor (LXR)alpha-regulated genes and enzymes involved in cholesterol homeostasis. Feeding SPI+ increased promoter binding of LXRalpha, expression of the transcription factor mRNA, and protein (P < 0.05). In a second experiment, male Sprague-Dawley rats were fed casein diets from postnatal d (PND) 24 to PND64 or were fed high-fat Western diets containing 5 g x kg(-1) cholesterol made with either casein or SPI+. Insulin resistance, steatosis, and hypercholesterolemia in the Western diet-fed rats were partially prevented by SPI+ (P < 0.05). Nuclear sterol receptor element binding protein (SREBP)-1c protein and mRNA and protein expression of enzymes involved in fatty acid synthesis were increased by feeding Western diets containing casein but not SPI+ (P < 0.05). These data suggest that activation of PPAR and LXR signaling and inhibition of SREBP-1c signaling may contribute to insulin sensitization and improved lipid homeostasis in SPI+-fed rats after consumption of diets high in fat and cholesterol.
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Mass spectrometric demonstration of the presence of liver carnitine palmitoyltransferase-I (CPT-I) in heart mitochondria of adult rats. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1794:431-7. [PMID: 19111953 DOI: 10.1016/j.bbapap.2008.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 10/17/2008] [Accepted: 11/07/2008] [Indexed: 01/03/2023]
Abstract
The carnitine palmitoyltransferase-I (CPT-I) enzymes catalyze the regulated step in overall mitochondrial fatty acid oxidation. The liver and muscle isoforms are expressed in liver and skeletal muscle respectively with the isoforms exhibiting different kinetic properties and apparent molecular weight masses. In contrast, the heart expresses both isoforms at the mRNA level. However, for the expression of the liver isoform at the protein level only indirect evidence is available, such as tagging with radiolabeled CPT-I inhibitors followed by SDS-PAGE separation and kinetic analysis using inhibitors. The importance of fatty acid oxidation in the heart and the potential regulation via the liver isoform of CPT-I demands proof of the liver isoform in the heart. Using a proteomic approach in the present study we demonstrate that rat heart mitochondria (a) contain both the muscle and liver isoforms; (b) both proteins retain their C- and N-termini; (c) the N-terminal alanine residues are acetylated; (d) and in rat heart mitochondria the liver isoform is phosphorylated on tyrosine 281. By providing amino acid sequence information this is the first unequivocal demonstration that the liver isoform of CPT-I is expressed at the protein level in adult rat heart mitochondria and that the apparent smaller molecular size of the muscle isoform is not due to proteolytic truncation.
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Inagaki T, Dutchak P, Zhao G, Ding X, Gautron L, Parameswara V, Li Y, Goetz R, Mohammadi M, Esser V, Elmquist JK, Gerard RD, Burgess SC, Hammer RE, Mangelsdorf DJ, Kliewer SA. Endocrine regulation of the fasting response by PPARalpha-mediated induction of fibroblast growth factor 21. Cell Metab 2007; 5:415-25. [PMID: 17550777 DOI: 10.1016/j.cmet.2007.05.003] [Citation(s) in RCA: 1185] [Impact Index Per Article: 69.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 03/28/2007] [Accepted: 05/03/2007] [Indexed: 12/14/2022]
Abstract
Peroxisome proliferator-activated receptor alpha (PPARalpha) regulates the utilization of fat as an energy source during starvation and is the molecular target for the fibrate dyslipidemia drugs. Here, we identify the endocrine hormone fibroblast growth factor 21 (FGF21) as a mediator of the pleiotropic actions of PPARalpha. FGF21 is induced directly by PPARalpha in liver in response to fasting and PPARalpha agonists. FGF21 in turn stimulates lipolysis in white adipose tissue and ketogenesis in liver. FGF21 also reduces physical activity and promotes torpor, a short-term hibernation-like state of regulated hypothermia that conserves energy. These findings demonstrate an unexpected role for the PPARalpha-FGF21 endocrine signaling pathway in regulating diverse metabolic and behavioral aspects of the adaptive response to starvation.
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Affiliation(s)
- Takeshi Inagaki
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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12
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Distler AM, Kerner J, Hoppel CL. Post-translational modifications of rat liver mitochondrial outer membrane proteins identified by mass spectrometry. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:628-36. [PMID: 17478130 PMCID: PMC1950290 DOI: 10.1016/j.bbapap.2007.03.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 03/13/2007] [Accepted: 03/14/2007] [Indexed: 12/17/2022]
Abstract
The identification of post-translational modifications is difficult especially for hydrophobic membrane proteins. Here we present the identification of several types of protein modifications on membrane proteins isolated from mitochondrial outer membranes. We show, in vivo, that the mature rat liver mitochondrial carnitine palmitoyltransferase-I enzyme is N-terminally acetylated, phosphorylated on two threonine residues, and nitrated on two tyrosine residues. We show that long chain acyl-CoA synthetase 1 is acetylated at both the N-terminal end and at a lysine residue and tyrosine residues are found to be phosphorylated and nitrated. For the three voltage-dependent anion channel isoforms present in the mitochondria, the N-terminal regions of the protein were determined and sites of phosphorylation were identified. These novel findings raise questions about regulatory aspects of carnitine palmitoyltransferase-I, long chain acyl-CoA synthetase and voltage dependent anion channel and further studies should advance our understanding about regulation of mitochondrial fatty acid oxidation in general and these three proteins in specific.
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Affiliation(s)
- Anne M. Distler
- Department of Medicine, Case Western Reserve University and Medical Research Service, Cleveland OH, 44106
- Department of Nutrition, Case Western Reserve University and Medical Research Service, Cleveland OH, 44106
| | - Janos Kerner
- Department of Medicine, Case Western Reserve University and Medical Research Service, Cleveland OH, 44106
- Department of Nutrition, Case Western Reserve University and Medical Research Service, Cleveland OH, 44106
| | - Charles L. Hoppel
- Department of Medicine, Case Western Reserve University and Medical Research Service, Cleveland OH, 44106
- Department of Pharmacology, Case Western Reserve University and Medical Research Service, Cleveland OH, 44106
- Louis Stokes Department of Veterans Affairs Medical Center, Cleveland OH, 44106
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Högberg H, Engblom L, Ekdahl A, Lidell V, Walum E, Alberts P. Temperature dependence of O2 consumption; opposite effects of leptin and etomoxir on respiratory quotient in mice. Obesity (Silver Spring) 2006; 14:673-82. [PMID: 16741269 DOI: 10.1038/oby.2006.76] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVES The aims were to compare the temperature dependence of the metabolic rate in young ob/ob mice with that in mature ob/ob and db/db mice and to examine the effect on the metabolic substrate preference of leptin and etomoxir in ob/ob, C57BL/6J (wild-type), and db/db mice. RESEARCH METHODS AND PROCEDURES In vivo oxygen consumption and carbon dioxide production were continuously measured by indirect calorimetry, and body temperature and total locomotor activity were measured by an implanted transponder. Leptin, etomoxir, or vehicle was administered intraperitoneally. RESULTS The temperature dependence of the metabolic rate of mature ob/ob and db/db mice were similar to that in wild-type mice. In young 6-week-old ob/ob mice, the metabolic rate was almost doubled at 15 degrees C. Leptin (2 x 3 mg/kg) decreased the respiratory quotient (RQ) and carbon dioxide production but did not alter oxygen consumption, body temperature, or locomotor activity in ob/ob and C57BL/6J mice and had no effect in the db/db mice. Etomoxir (2 x 30 mg/kg) enhanced RQ and decreased oxygen consumption, carbon dioxide production, and body temperature in ob/ob, C57BL/6J, and db/db mice. Total locomotor activity was reduced in ob/ob and C57BL/6J mice. DISCUSSION In young ob/ob mice, the temperature sensitivity was enhanced compared with mature mice. Leptin and etomoxir had opposite effects on metabolic substrate preference. Leptin and lowered environmental temperature increased the relative fat oxidation as indicated by decreased RQ, possibly through activation of the sympathetic nervous system.
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Lopaschuk GD. Malonyl CoA control of fatty acid oxidation in the diabetic rat heart. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002; 498:155-65. [PMID: 11900364 DOI: 10.1007/978-1-4615-1321-6_21] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Increased fatty acid metabolism can decrease cardiac function and efficiency, and may therefore contribute to the outcome of ischemic injury in the diabetic. Alterations in the control of myocardial malonyl CoA levels is an important contributing factor to these high fatty acid oxidation rates. This includes alterations in AMPK, ACC, and MCD activity in the diabetic rat heart. A further understanding of how malonyl CoA controls fatty acid oxidation in the diabetic heart should help identify new targets for pharmacological intervention which decreases the reliance of the heart on fatty acid oxidation, and ultimately improves heart function.
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Affiliation(s)
- G D Lopaschuk
- Cardiovascular Research Group, University of Alberta, Edmonton, Canada
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15
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Subcellular Distributuon of Mitochondrial Carnitine Palmitoyltransferase I in Rat Liver. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002. [DOI: 10.1007/0-306-46818-2_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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16
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Fraser F, Corstorphine CG, Price NT, Zammit VA. Evidence that carnitine palmitoyltransferase I (CPT I) is expressed in microsomes and peroxisomes of rat liver. Distinct immunoreactivity of the N-terminal domain of the microsomal protein. FEBS Lett 1999; 446:69-74. [PMID: 10100617 DOI: 10.1016/s0014-5793(99)00179-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mitochondria, microsomes and peroxisomes all express overt (cytosol-facing) carnitine palmitoyltransferase activity that is inhibitable by malonyl-CoA. The overt carnitine palmitoyltransferase activity (CPTo) associated with the different fractions was measured. Mitochondria accounted for 65% of total cellular CPTo activity, with the microsomal and peroxisomal contributions accounting for the remaining 25% and 10%, respectively. In parallel experiments, rat livers were perfused in situ with medium containing dinitrophenyl (DNP)-etomoxir in order to inhibit quantitatively and label covalently (with DNP-etomoxiryl-CoA) the molecular species responsible for CPTo activity in each of the membrane systems under near-physiological conditions. In all three membrane fractions, a single protein with an identical molecular mass of approximately 88,000 kDa (p88) was labelled after DNP-etomoxir perfusion of the liver. The abundance of labelled p88 was quantitatively related to the respective specific activities of CPTo in each fraction. On Western blots the same protein was immunoreactive with three anti-peptide antibodies raised against linear epitopes of the cytosolic N- and C-domains and of the inter-membrane space loop (L) domain of the mitochondrial enzyme (L-CPT I). However, the reaction of the microsomal protein with the anti-N peptide antibody (raised against epitope Val-14-Lys-29 of CPT I) was an order of magnitude stronger than expected from either microsomal CPTo activity or its DNP-etomoxiryl-CoA labelling. This suggests that the N-terminal domain of the microsomal protein differs from that in the mitochondrial or peroxisomal protein. This conclusion was confirmed using antibody back-titration experiments, in which the binding of anti-N and anti-C antibodies by mitochondria and microsomes was quantified.
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Affiliation(s)
- F Fraser
- Hannah Research Institute, Ayr, UK
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17
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Deems RO, Anderson RC, Foley JE. Hypoglycemic effects of a novel fatty acid oxidation inhibitor in rats and monkeys. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:R524-8. [PMID: 9486313 DOI: 10.1152/ajpregu.1998.274.2.r524] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Increased fatty acid oxidation contributes to hyperglycemia in patients with non-insulin-dependent diabetes mellitus. To improve glucose homeostasis in these patients, we have designed a novel, reversible inhibitor of carnitine palmitoyl-transferase I (CPT I) that potently inhibits fatty acid oxidation. SDZ-CPI-975 significantly lowered glucose levels in normal 18-h-fasted nonhuman primates and rats. In rats, glucose lowering required fatty acid oxidation inhibition of > or = 70%, as measured by beta-hydroxybutyrate levels, the end product of beta-oxidation. In cynomolgus monkeys, comparable glucose lowering was achieved with more modest lowering of beta-hydroxybutyrate levels. SDZ-CPI-975 did not increase glucose utilization by heart muscle, suggesting that CPT I inhibition with SDZ-CPI-975 would not induce cardiac hypertrophy. This was in contrast to the irreversible CPT I inhibitor etomoxir. These results demonstrate that SDZ-CPI-975 effectively inhibited fatty acid oxidation and lowered blood glucose levels in two species. Thus reversible inhibitors of CPT I represent a class of novel hypoglycemic agents that inhibit fatty acid oxidation without inducing cardiac hypertrophy.
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Affiliation(s)
- R O Deems
- Novartis Pharmaceuticals Corporation, East Hanover, New Jersey 07936, USA
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18
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Zhu H, Shi J, de Vries Y, Arvidson DN, Cregg JM, Woldegiorgis G. Functional studies of yeast-expressed human heart muscle carnitine palmitoyltransferase I. Arch Biochem Biophys 1997; 347:53-61. [PMID: 9344464 DOI: 10.1006/abbi.1997.0314] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Long-chain fatty acids are the primary source of energy production in the heart. Carnitine palmitoyltransferase I (CPT-I) catalyzes the first reaction in the transport of long-chain fatty acids from the cytoplasm to the mitochondrion, a rate-limiting step in beta-oxidation. In this study, we report the functional expression of the human heart/skeletal muscle isoform of CPT-I (M-CPT-I) in the yeast Pichia pastoris. Screening of a human heart cDNA library with cDNA fragments encoding the rat heart M-CPT-I resulted in the isolation of a single full-length human heart M-CPT-I cDNA clone. The clone has an open reading frame of 2316 bp with a 5' untranslated region of 38 bp and a 256-bp 3' untranslated region with the poly(A)+ addition sequence AATAAA. The predicted protein has 772 amino acids and a molecular mass of 88 kDa. Northern blot analysis of mRNAs from different human tissues using the human M-CPT-I cDNA as a probe revealed an abundant transcript of approximately 3.1 kb that was only present in human heart and skeletal muscle tissue. Expression of the human M-CPT-I cDNA in P. pastoris, a yeast with no endogenous CPT activity, produced an 80-kDa protein that was located in the mitochondria. Isolated mitochondria from the M-CPT-I expression strain exhibited a malonyl-coenzyme A (CoA)-sensitive CPT activity that was detergent labile. The I50 for malonyl-CoA inhibition of the yeast-expressed M-CPT-I was 69 nM, and the Kms for carnitine and palmitoyl-CoA were 666 and 42 microM, respectively. The I50 for malonyl-CoA inhibition of the heart enzyme is 30 times lower than that of the yeast-expressed liver CPT-I, and the Km for carnitine is more than 20 times higher than that of the liver CPT-I. This is the first report of the expression of a heart CPT-I in a system devoid of endogenous CPT activity and the functional characterization of a human heart M-CPT-I in the absence of the liver isoform and CPT-II.
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Affiliation(s)
- H Zhu
- Department of Biochemistry and Molecular Biology, Oregon Graduate Institute of Science and Technology, Portland, Oregon 97291-1000, USA
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19
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Zhu H, Shi J, Cregg JM, Woldegiorgis G. Reconstitution of highly expressed human heart muscle carnitine palmitoyltransferase I. Biochem Biophys Res Commun 1997; 239:498-502. [PMID: 9344859 DOI: 10.1006/bbrc.1997.7494] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The human heart muscle carnitine palmitoyltransferase I (M-CPTI) gene was expressed at high levels from a strain of the methylotrophic yeast Pichia pastoris containing approximately 24 copies of the expression vector. Levels of M-CPTI were more than ten-fold higher than previously reported by our group with a single-copy strain (Arch. Biochem. Biophys., in press) and were sufficient to perform reconstitution studies on the membrane protein, a key step in purification and structural analysis of the enzyme. Solubilization of yeast mitochondria containing M-CPTI in 5% Triton X-100 abolished M-CPTI activity. The detergent-inactivated M-CPTI was then reconstituted by removal of the detergent in the presence of phospholipids. The reconstituted proteoliposomes exhibited M-CPTI activity of 2.4 nmol palmitoylcarnitine formed/mg protein/min, a recovery of 23% of the activity present in the starting mitochondrial preparation. The malonyl-CoA sensitivity of the reconstituted reactivated M-CPTI was 88%. This is the first demonstration of direct reactivation of malonyl-CoA-sensitive M-CPTI activity from solubilized materials from any organism. Previously, M-CPTI was presumed to be irreversibly inactivated by detergents.
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Affiliation(s)
- H Zhu
- Department of Biochemistry and Molecular Biology, Oregon Graduate Institute of Science and Technology, Portland 97291-1000, USA
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20
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Portilla D. Carnitine palmitoyl-transferase enzyme inhibition protects proximal tubules during hypoxia. Kidney Int 1997; 52:429-37. [PMID: 9263998 DOI: 10.1038/ki.1997.349] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The role of inhibition of the CPT enzymes responsible for accumulation of long chain acylcarnitines (LCAC) during hypoxia in the proximal tubule has not been previously examined. We have characterized CPT enzyme activities in mitochondrial fractions of rabbit proximal tubules. Malonyl CoA-sensitive CPT I activity (1.1 +/- 0.3 nmol/min/mg protein), and detergent-solubilized, malonyl CoA-insensitive CPT II activity (2.3 +/- 0.4 nmol/min/mg protein) were readily detected in proximal tubule mitochondrial fractions. Subjecting rabbit proximal tubules to various periods of hypoxia did not significantly change mitochondrial CPT I or CPT II activities. Thirty minutes of hypoxia resulted in an increase in lysophospholipid mass from 440 +/- 105 to 720 +/- 93 pmol/mg protein, N = 5, LCAC mass from 79 +/- 11 to 618 +/- 34 pmol/mg protein, N = 5, and lactate dehydrogenase (LDH) release from 9 +/- 1% to 46 +/- 3%, N = 8. Pretreatment of proximal tubules with two different CPT inhibitors, glybenclamide (Glyb) 400 microM and oxfenicine (Oxfe) 1 mM, resulted in reduction in the magnitude of hypoxia-induced lysophospholipid formation 490 +/- 160 (Glyb), 342 +/- 150 pmol/mg protein (Oxfe), N = 4, hypoxia-induced LCAC formation 295 +/- 27 (Glyb), 128 +/- 16 pmol/mg protein (Oxfe). N = 5, and LDH release 25 +/- 1% (Glyb) and 19 +/- 2% (Oxfe), N = 8. The protective effect of CPT inhibition was also associated with increased production of lactate suggesting the modulation of a substrate-mediated metabolic switch. Immunoblots demonstrated that hypoxia caused a time dependent hydrolysis of fodrin-alpha subunit and that CPT inhibition protected against hypoxia-induced fodrin proteolysis. These data suggest a unifying hypothesis that links phospholipase A2 (PLA2) activation, and hypoxia-mediated fodrin proteolysis to the proximal tubule mitochondrial CPT system. I propose that CPT inhibition may represent a novel mechanism to ameliorate proximal tubule cell death during hypoxia.
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Affiliation(s)
- D Portilla
- Department of Medicine, University of Arkansas for Medical Sciences, Little Rock, USA
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21
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McGarry JD, Brown NF. The mitochondrial carnitine palmitoyltransferase system. From concept to molecular analysis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 244:1-14. [PMID: 9063439 DOI: 10.1111/j.1432-1033.1997.00001.x] [Citation(s) in RCA: 1170] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
First conceptualized as a mechanism for the mitochondrial transport of long-chain fatty acids in the early 1960s, the carnitine palmitoyltransferase (CPT) system has since come to be recognized as a pivotal component of fuel homeostasis. This is by virtue of the unique sensitivity of the outer membrane CPT I to the simple molecule, malonyl-CoA. In addition, both CPT I and the inner membrane enzyme, CPT II, have proved to be loci of inherited defects, some with disastrous consequences. Early efforts using classical approaches to characterize the CPT proteins in terms of structure/function/regulatory relationships gave rise to confusion and protracted debate. By contrast, recent application of molecular biological tools has brought major enlightenment at an exponential pace. Here we review some key developments of the last 20 years that have led to our current understanding of the physiology of the CPT system, the structure of the CPT isoforms, the chromosomal localization of their respective genes, and the identification of mutations in the human population.
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Affiliation(s)
- J D McGarry
- Department of Internal Medicine and Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235-9135, USA
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23
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Land JM, Mistry S, Squier M, Hope P, Ghadiminejad I, Orford M, Saggerson D. Neonatal carnitine palmitoyltransferase-2 deficiency: a case presenting with myopathy. Neuromuscul Disord 1995; 5:129-37. [PMID: 7767092 DOI: 10.1016/0960-8966(94)00037-a] [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: 01/27/2023]
Abstract
Mitochondria were isolated from liver, heart and skeletal muscle of a 34-day-old female infant who died from a myopathic illness. Muscle biopsy showed lipid accumulation and no obvious pathology in any other organ. Enzymatic analysis of skeletal muscle extracts revealed normal activities of the markers pyruvate dehydrogenase and citrate synthase. Malonyl-CoA-sensitive carnitine palmitoyltransferase (CPT1) was detected but malonyl-CoA-insensitive carnitine palmitoyltransferase (CPT2) appeared to be absent. Quantitative immunoblotting revealed the presence of a normal abundance of CPT2 protein in the patient's muscle. It is concluded that enzymically inactive CPT2 protein was present.
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Affiliation(s)
- J M Land
- Nuffield Department of Clinical Biochemistry, John Radcliffe Hospital, Oxford, U.K
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Zierz S. Limited trypsin proteolysis renders carnitine palmitoyltransferase insensitive to inhibition by malonyl-CoA in patients with muscle carnitine palmitoyltransferase deficiency. THE CLINICAL INVESTIGATOR 1994; 72:957-60. [PMID: 7711426 DOI: 10.1007/bf00577735] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Carnitine palmitoyltransferase (CPT) was studied in muscle homogenates of two patients with muscle CPT deficiency heterozygous for the Ser-113 Leu mutation in the CPT II gene. Total CPT activity was normal in both patients but was almost completely inhibited by malonyl-CoA and Triton X-100 whereas in controls 38% and 58% of total activity remained in the presence of malonyl-CoA and Triton X-100, respectively. The addition of 1% Tween 20 abolished about half of the activity in patients but not in controls. Preincubation of muscle homogenate with trypsin slightly increased the total activity and rendered the activity greatly insensitive to inhibition by malonyl-CoA in both patients and controls. The data support the view that in patients with muscle CPT deficiency both CPT I and II are active, but that CPT II is abnormally accessible to inhibition by malonyl-CoA.
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Affiliation(s)
- S Zierz
- Neurologische Universitätsklinik Bonn, Germany
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25
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Weis BC, Cowan AT, Brown N, Foster DW, McGarry JD. Use of a selective inhibitor of liver carnitine palmitoyltransferase I (CPT I) allows quantification of its contribution to total CPT I activity in rat heart. Evidence that the dominant cardiac CPT I isoform is identical to the skeletal muscle enzyme. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)47214-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Expression of a cDNA for rat liver carnitine palmitoyltransferase I in yeast establishes that catalytic activity and malonyl-CoA sensitivity reside in a single polypeptide. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)47213-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Lopaschuk GD, Belke DD, Gamble J, Itoi T, Schönekess BO. Regulation of fatty acid oxidation in the mammalian heart in health and disease. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1213:263-76. [PMID: 8049240 DOI: 10.1016/0005-2760(94)00082-4] [Citation(s) in RCA: 391] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- G D Lopaschuk
- Department of Pediatrics, Faculty of Medicine, University of Alberta, Edmonton, Canada
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28
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Weis B, Esser V, Foster D, McGarry J. Rat heart expresses two forms of mitochondrial carnitine palmitoyltransferase I. The minor component is identical to the liver enzyme. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32222-6] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Kerner J, Zaluzec E, Gage D, Bieber L. Characterization of the malonyl-CoA-sensitive carnitine palmitoyltransferase (CPTo) of a rat heart mitochondrial particle. Evidence that the catalytic unit is CPTi. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37181-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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30
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Kolodziej MP, Zammit VA. Mature carnitine palmitoyltransferase I retains the N-terminus of the nascent protein in rat liver. FEBS Lett 1993; 327:294-6. [PMID: 8348957 DOI: 10.1016/0014-5793(93)81007-m] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Carnitine palmitoyltransferase I was isolated from octylglucoside extracts of rat liver mitochondrial outer membranes. This native enzyme was digested proteolytically with V8 protease. Five major peptides were obtained all of which were found in the amino acid sequence predicted from the full-length cDNA sequence of the protein. One peptide was found to correspond to the extreme N-terminus of the deduced amino acid sequence. Therefore, the mature protein retains the N-terminus of the nascent protein after import into the mitochondrial membrane. Knowledge of the identity of the N-terminus of the mature protein allows a reappraisal of the role of the two main. N-terminal hydrophobic domains of the protein and of the possible topology of the protein within the membrane.
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Esser V, Britton C, Weis B, Foster D, McGarry J. Cloning, sequencing, and expression of a cDNA encoding rat liver carnitine palmitoyltransferase I. Direct evidence that a single polypeptide is involved in inhibitor interaction and catalytic function. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53392-5] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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