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Wang Y, Patti GJ. The Warburg effect: a signature of mitochondrial overload. Trends Cell Biol 2023; 33:1014-1020. [PMID: 37117116 PMCID: PMC10600323 DOI: 10.1016/j.tcb.2023.03.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 04/30/2023]
Abstract
A long-standing question in cancer biology has been why oxygenated tumors ferment the majority of glucose they consume to lactate rather than oxidizing it in their mitochondria, a phenomenon known as the 'Warburg effect.' An abundance of evidence shows not only that most cancer cells have fully functional mitochondria but also that mitochondrial activity is important to proliferation. It is therefore difficult to rationalize the metabolic benefit of cancer cells switching from respiration to fermentation. An emerging perspective is that rather than mitochondrial metabolism being suppressed in tumors, as is often suggested, mitochondrial activity increases to the level of saturation. As such, the Warburg effect becomes a signature of excess glucose being released as lactate due to mitochondrial overload.
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Affiliation(s)
- Yahui Wang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Gary J Patti
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Medicine, Washington University in St. Louis, St. Louis, MO 63130, USA; Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63130, USA.
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2
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Lewandowski ED. Metabolic flux in the driver's seat during cardiac health and disease. J Mol Cell Cardiol 2023; 182:15-24. [PMID: 37451081 PMCID: PMC10529670 DOI: 10.1016/j.yjmcc.2023.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/16/2023] [Accepted: 07/06/2023] [Indexed: 07/18/2023]
Abstract
Cardiac function is a dynamic process that must adjust efficiently to the immediate demands of physical state and activity. So too, the metabolic support of cardiac function is a dynamic process that must respond, in time, to the demands of cardiac function and viability. Flux through metabolic pathways provides chemical energy and generates signaling molecules that regulate activity among intracellular compartments to meet these demands. Thus, flux through metabolic pathways provides a dynamic mode of support of cardiomyocytes during physiological and pathophysiological challenges. Any inability of metabolic flux to keep pace with the demands of the cardiomyocyte results in progressive dysfunction that contributes to cardiac disease. Thus, the priority in maintaining and regulating flux through metabolic pathways in the cardiomyocyte cannot be understated. Great potential exists in current efforts to elucidate metabolic mechanisms as therapeutic targets for the diseased heart. As a consequence, detecting metabolic flux in the functioning myocardium of the heart, under normal and diseased conditions, is essential in elucidating the metabolic basis of contractile dysfunction. As a companion to the 2022 ISHR Research Achievement Award lecture, this review examines the use and applications of stable isotope kinetics to quantify metabolic flux through intermediary pathways and the exchange and transport of intermediates across the mitochondrial membrane and sarcolemma of intact functioning hearts in determining how these intracellular events are coordinated to support cardiac function and health. Finally, this work reviews recently demonstrated metabolic defects in diseased hearts and the potential for metabolic alleviation of heart disease.
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Affiliation(s)
- E Douglas Lewandowski
- Department of Internal Medicine and Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, United States of America.
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3
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Tarasov KV, Chakir K, Riordon DR, Lyashkov AE, Ahmet I, Perino MG, Silvester AJ, Zhang J, Wang M, Lukyanenko YO, Qu JH, Barrera MCR, Juhaszova M, Tarasova YS, Ziman B, Telljohann R, Kumar V, Ranek M, Lammons J, Bychkov R, de Cabo R, Jun S, Keceli G, Gupta A, Yang D, Aon MA, Adamo L, Morrell CH, Otu W, Carroll C, Chambers S, Paolocci N, Huynh T, Pacak K, Weiss R, Field L, Sollott SJ, Lakatta EG. A remarkable adaptive paradigm of heart performance and protection emerges in response to marked cardiac-specific overexpression of ADCY8. eLife 2022; 11:e80949. [PMID: 36515265 PMCID: PMC9822292 DOI: 10.7554/elife.80949] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 12/08/2022] [Indexed: 12/15/2022] Open
Abstract
Adult (3 month) mice with cardiac-specific overexpression of adenylyl cyclase (AC) type VIII (TGAC8) adapt to an increased cAMP-induced cardiac workload (~30% increases in heart rate, ejection fraction and cardiac output) for up to a year without signs of heart failure or excessive mortality. Here, we show classical cardiac hypertrophy markers were absent in TGAC8, and that total left ventricular (LV) mass was not increased: a reduced LV cavity volume in TGAC8 was encased by thicker LV walls harboring an increased number of small cardiac myocytes, and a network of small interstitial proliferative non-cardiac myocytes compared to wild type (WT) littermates; Protein synthesis, proteosome activity, and autophagy were enhanced in TGAC8 vs WT, and Nrf-2, Hsp90α, and ACC2 protein levels were increased. Despite increased energy demands in vivo LV ATP and phosphocreatine levels in TGAC8 did not differ from WT. Unbiased omics analyses identified more than 2,000 transcripts and proteins, comprising a broad array of biological processes across multiple cellular compartments, which differed by genotype; compared to WT, in TGAC8 there was a shift from fatty acid oxidation to aerobic glycolysis in the context of increased utilization of the pentose phosphate shunt and nucleotide synthesis. Thus, marked overexpression of AC8 engages complex, coordinate adaptation "circuity" that has evolved in mammalian cells to defend against stress that threatens health or life (elements of which have already been shown to be central to cardiac ischemic pre-conditioning and exercise endurance cardiac conditioning) that may be of biological significance to allow for proper healing in disease states such as infarction or failure of the heart.
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Affiliation(s)
- Kirill V Tarasov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Khalid Chakir
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Daniel R Riordon
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Alexey E Lyashkov
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Ismayil Ahmet
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Maria Grazia Perino
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Allwin Jennifa Silvester
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Jing Zhang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Mingyi Wang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Yevgeniya O Lukyanenko
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Jia-Hua Qu
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Miguel Calvo-Rubio Barrera
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Yelena S Tarasova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Bruce Ziman
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Richard Telljohann
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Vikas Kumar
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Mark Ranek
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - John Lammons
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Rostislav Bychkov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Rafael de Cabo
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Seungho Jun
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Gizem Keceli
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Ashish Gupta
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Luigi Adamo
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Christopher H Morrell
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Walter Otu
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Cameron Carroll
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Shane Chambers
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Nazareno Paolocci
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Thanh Huynh
- Section on Medical Neuroendocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of HealthBethesdaUnited States
| | - Karel Pacak
- Section on Medical Neuroendocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of HealthBethesdaUnited States
| | - Robert Weiss
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Loren Field
- Kraennert Institute of Cardiology, Indiana University School of MedicineIdianapolisUnited States
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
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4
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Wang Y, Stancliffe E, Fowle-Grider R, Wang R, Wang C, Schwaiger-Haber M, Shriver LP, Patti GJ. Saturation of the mitochondrial NADH shuttles drives aerobic glycolysis in proliferating cells. Mol Cell 2022; 82:3270-3283.e9. [PMID: 35973426 PMCID: PMC10134440 DOI: 10.1016/j.molcel.2022.07.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 05/12/2022] [Accepted: 07/14/2022] [Indexed: 12/21/2022]
Abstract
Proliferating cells exhibit a metabolic phenotype known as "aerobic glycolysis," which is characterized by an elevated rate of glucose fermentation to lactate irrespective of oxygen availability. Although several theories have been proposed, a rationalization for why proliferating cells seemingly waste glucose carbon by excreting it as lactate remains elusive. Using the NCI-60 cell lines, we determined that lactate excretion is strongly correlated with the activity of mitochondrial NADH shuttles, but not proliferation. Quantifying the fluxes of the malate-aspartate shuttle (MAS), the glycerol 3-phosphate shuttle (G3PS), and lactate dehydrogenase under various conditions demonstrated that proliferating cells primarily transform glucose to lactate when glycolysis outpaces the mitochondrial NADH shuttles. Increasing mitochondrial NADH shuttle fluxes decreased glucose fermentation but did not reduce the proliferation rate. Our results reveal that glucose fermentation, a hallmark of cancer, is a secondary consequence of MAS and G3PS saturation rather than a unique metabolic driver of cellular proliferation.
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Affiliation(s)
- Yahui Wang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Ethan Stancliffe
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Medicine, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Ronald Fowle-Grider
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Medicine, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Rencheng Wang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Cheng Wang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Michaela Schwaiger-Haber
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Leah P Shriver
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Medicine, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Gary J Patti
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Medicine, Washington University in St. Louis, St. Louis, MO 63130, USA; Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63130, USA; Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO 63130, USA.
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5
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Exenatide and Dapagliflozin Combination Enhances Sertoli Cell Secretion of Key Metabolites for Spermatogenesis. Biomedicines 2022; 10:biomedicines10051115. [PMID: 35625851 PMCID: PMC9139030 DOI: 10.3390/biomedicines10051115] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 05/04/2022] [Accepted: 05/10/2022] [Indexed: 01/14/2023] Open
Abstract
The incidence of metabolic diseases such as type 2 diabetes mellitus (DM) and obesity has been increasing dramatically. Both diseases are closely linked and new approaches for type 2 DM treatment aim to enable weight loss. A combined therapy of dapagliflozin and exenatide has been used against type 2 DM, influencing allbody glucose dynamics. Spermatogenesis is highly dependent on the metabolic cooperation established between Sertoli cells (SCs) and developing germ cells. To study the effects of dapagliflozin and exenatide on SC metabolism, mouse SCs were treated in the presence of sub-pharmacologic, pharmacologic, and supra-pharmacologic concentrations of dapagliflozin (50, 500, 5000 nM, respectively) and/or exenatide (2.5, 25, 250 pM, respectively). Cytotoxicity of these compounds was evaluated and the glycolytic profile, glycogen content assay, and lipid accumulation of SCs were determined. Dapagliflozin treatment decreased fat cellular deposits, demonstrating its anti-obesity properties at the cellular level. Polytherapy of exenatide plus dapagliflozin increased lactate production by SCs, which has been reported to improve sperm production and quality. Thus, the results herein suggest that the use of these two pharmacological agents can protect male fertility, while improving their glucose homeostasis and inducing weight loss.
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6
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Mahar R, Chang MC, Merritt ME. Measuring NQO1 Bioactivation Using [ 2H 7]Glucose. Cancers (Basel) 2021; 13:4165. [PMID: 34439319 PMCID: PMC8392257 DOI: 10.3390/cancers13164165] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/06/2021] [Accepted: 08/17/2021] [Indexed: 12/02/2022] Open
Abstract
Treatment of cancers with β-lapachone causes NAD(P)H: quinone oxidoreductase 1 (NQO1) to generate an unstable hydroquinone that regenerates itself in a futile cycle while producing reactive oxygen species (ROS) in the form of superoxide and subsequently hydrogen peroxide. Rapid accumulation of ROS damages DNA, hyperactivates poly-ADP-ribose polymerase-I, causes massive depletion of NAD+/ATP, and hampers glycolysis. Cells overexpressing NQO1 subsequently die rapidly through an NAD+-keresis mechanism. Assessing changes in glycolytic rates caused by NQO1 bioactivation would provide a means of assessing treatment efficacy, potentially lowering the chemotherapeutic dosage, and reducing off-target toxicities. NQO1-mediated changes in glycolytic flux were readily detected in A549 (lung), MiaPaCa2 (pancreatic), and HCT-116 (colon) cancer cell lines by 2H-NMR after administration of [2H7]glucose. The deuterated metabolic products 2H-lactate and HDO were quantified, and linear relationships with glucose consumption for both products were observed. The higher concentration of HDO compared to 2H-lactate allows for more sensitive measurement of the glycolytic flux in cancer. Gas chromatography-mass spectrometry analysis agreed with the NMR results and confirmed downregulated energy metabolism in NQO1+ cells after β-lapachone treatment. The demonstrated method is ideal for measuring glycolytic rates, the effects of chemotherapeutics that target glycolysis, and has the potential for in vivo translation.
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Affiliation(s)
| | | | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.M.); (M.C.C.)
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7
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Chiao YA, Chakraborty AD, Light CM, Tian R, Sadoshima J, Shi X, Gu H, Lee CF. NAD + Redox Imbalance in the Heart Exacerbates Diabetic Cardiomyopathy. Circ Heart Fail 2021; 14:e008170. [PMID: 34374300 PMCID: PMC8373812 DOI: 10.1161/circheartfailure.120.008170] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Diabetes is a risk factor for heart failure and promotes cardiac dysfunction. Diabetic tissues are associated with nicotinamide adenine dinucleotide (NAD+) redox imbalance; however, the hypothesis that NAD+ redox imbalance causes diabetic cardiomyopathy has not been tested. This investigation used mouse models with altered NAD+ redox balance to test this hypothesis. METHODS Diabetic stress was induced in mice by streptozotocin. Cardiac function was measured by echocardiography. Heart and plasma samples were collected for biochemical, histological, and molecular analyses. Two mouse models with altered NAD+ redox states (1, Ndufs4 [NADH:ubiquinone oxidoreductase subunit S4] knockout, cKO, and 2, NAMPT [nicotinamide phosphoribosyltranferase] transgenic mice, NMAPT) were used. RESULTS Diabetic stress caused cardiac dysfunction and lowered NAD+/NADH ratio (oxidized/reduced ratio of nicotinamide adenine dinucleotide) in wild-type mice. Mice with lowered cardiac NAD+/NADH ratio without baseline dysfunction, cKO mice, were challenged with chronic diabetic stress. NAD+ redox imbalance in cKO hearts exacerbated systolic (fractional shortening: 27.6% versus 36.9% at 4 weeks, male cohort P<0.05), and diastolic dysfunction (early-to-late ratio of peak diastolic velocity: 0.99 versus 1.20, P<0.05) of diabetic mice in both sexes. Collagen levels and transcripts of fibrosis and extracellular matrix-dependent pathways did not show changes in diabetic cKO hearts, suggesting that the exacerbated cardiac dysfunction was due to cardiomyocyte dysfunction. NAD+ redox imbalance promoted superoxide dismutase 2 acetylation, protein oxidation, troponin I S150 phosphorylation, and impaired energetics in diabetic cKO hearts. Importantly, elevation of cardiac NAD+ levels by NAMPT normalized NAD+ redox balance, alleviated cardiac dysfunction (fractional shortening: 40.2% versus 24.8% in cKO:NAMPT versus cKO, P<0.05; early-to-late ratio of peak diastolic velocity: 1.32 versus 1.04, P<0.05), and reversed pathogenic mechanisms in diabetic mice. CONCLUSIONS Our results show that NAD+ redox imbalance to regulate acetylation and phosphorylation is a critical mediator of the progression of diabetic cardiomyopathy and suggest the therapeutic potential for diabetic cardiomyopathy by harnessing NAD+ metabolism.
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Affiliation(s)
- Ying Ann Chiao
- Aging and Metabolism Research Program (Y.A.C., A.D.C.), Oklahoma Medical Research Foundation, Oklahoma City
| | - Akash Deep Chakraborty
- Aging and Metabolism Research Program (Y.A.C., A.D.C.), Oklahoma Medical Research Foundation, Oklahoma City.,Cardiovascular Biology Research Program (A.D.C., C.M.L., C.F.L.), Oklahoma Medical Research Foundation, Oklahoma City
| | - Christine M Light
- Cardiovascular Biology Research Program (A.D.C., C.M.L., C.F.L.), Oklahoma Medical Research Foundation, Oklahoma City
| | - Rong Tian
- Mitochondria and Metabolism Center, University of Washington, Seattle (R.T.). Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Newark (J.S.)
| | | | - Xiaojian Shi
- Arizona Metabolomics Laboratory, College of Health Solutions, Arizona State University, Scottsdale (X.S., H.G.)
| | - Haiwei Gu
- Arizona Metabolomics Laboratory, College of Health Solutions, Arizona State University, Scottsdale (X.S., H.G.)
| | - Chi Fung Lee
- Cardiovascular Biology Research Program (A.D.C., C.M.L., C.F.L.), Oklahoma Medical Research Foundation, Oklahoma City.,Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City (C.F.L.)
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8
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The Effect of a 7-Week Training Period on Changes in Skin NADH Fluorescence in Highly Trained Athletes. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10155133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The study aimed to evaluate the changes of nicotinamide adenine dinucleotide (NADH) fluorescence in the reduced form in the superficial skin layer, resulting from a 7-week training period in highly trained competitive athletes (n = 41). The newly, non-invasive flow mediated skin fluorescence (FMSF) method was implemented to indirectly evaluate the mitochondrial activity by NADH fluorescence. The FMSF measurements were taken before and after an exercise treadmill test until exhaustion. We found that athletes showed higher post-training values in basal NADH fluorescence (pre-exercise: 41% increase; post-exercise: 49% increase). Maximum NADH fluorescence was also higher after training both pre- (42% increase) and post-exercise (47% increase). Similar changes have been revealed before and after exercise for minimal NADH fluorescence (before exercise: 39% increase; after exercise: 47% increase). In conclusion, physical training results in an increase in the skin NADH fluorescence levels at rest and after exercise in athletes.
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9
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Palma M, Trenkner LH, Rito J, Tavares LC, Silva E, Glencross BD, Jones JG, Wade NM, Viegas I. Limitations to Starch Utilization in Barramundi ( Lates calcarifer) as Revealed by NMR-Based Metabolomics. Front Physiol 2020; 11:205. [PMID: 32265728 PMCID: PMC7098972 DOI: 10.3389/fphys.2020.00205] [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: 10/23/2019] [Accepted: 02/21/2020] [Indexed: 12/17/2022] Open
Abstract
Practical diets for commercial barramundi production rarely contain greater than 10% starch, used mainly as a binding agent during extrusion. Alternative ingredients such as digestible starch have shown some capacity to spare dietary protein catabolism to generate glucose. In the present study, a carnivorous fish species, the Asian seabass (Lates calcarifer) was subjected to two diets with the same digestible energy: Protein (P) – with high protein content (no digestible starch); and Starch (S) – with high digestible (pregelatinized) starch content. The effects of a high starch content diet on hepatic glycogen synthesis as well as the muscle and liver metabolome were studied using a complementary approach of 1H and 2H NMR. The hepatosomatic index was lower for fish fed high starch content diet while the concentration of hepatic glycogen was similar between groups. However, increased glycogen synthesis via the direct pathway was observed in the fish fed high starch content diet which is indicative of increased carbohydrate utilization. Multivariate analysis also showed differences between groups in the metabolome of both tissues. Univariate analysis revealed more variations in liver than in muscle of fish fed high starch content diet. Variations in metabolome were generally in agreement with the increase in the glycogen synthesis through direct pathway, however, this metabolic shift seemed to be insufficient to keep the growth rate as ensured by the diet with high protein content. Although liver glycogen does not make up a substantial quantity of total stored dietary energy in carnivorous fish, it is a key regulatory intermediate in dietary energy utilization.
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Affiliation(s)
- Mariana Palma
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Lauren H Trenkner
- CSIRO Agriculture and Food, Queensland Biosciences Precinct, Brisbane, QLD, Australia.,School of Agriculture and Food Science, The University of Queensland, Brisbane, QLD, Australia
| | - João Rito
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.,Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Ludgero C Tavares
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Emanuel Silva
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Brett D Glencross
- CSIRO Agriculture and Food, Queensland Biosciences Precinct, Brisbane, QLD, Australia
| | - John G Jones
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Nicholas M Wade
- CSIRO Agriculture and Food, Queensland Biosciences Precinct, Brisbane, QLD, Australia
| | - Ivan Viegas
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.,Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
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10
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Yang X, Zhao Y, Sun Q, Yang Y, Gao Y, Ge W, Liu J, Xu X, Zhang J. Adenosine accumulation causes metabolic disorders in testes and associates with lower testosterone level in obese mice. Mol Reprod Dev 2020; 87:241-250. [PMID: 32026564 DOI: 10.1002/mrd.23321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 01/05/2020] [Indexed: 12/27/2022]
Abstract
Overweight and obese men face numerous health problems, including type 2 diabetes, subfertility, and even infertility. However, few studies have focused on the effects of nutritional status and obesity-related regulatory signals on fertility deficiency. Our previous observations have shown that the elevation of plasma 5'-adenosine monophosphate (5'-AMP) and the accumulation of adenosine in liver and muscle of obese diabetic db/db mice are related to insulin resistance. Here, we found that adenosine accumulation in testis is a common marker of both genetic obesity and high-fat-diet induced obese mice. An messenger RNA sequencing analysis indicated that 78 upregulated genes and 155 downregulated genes in the testis of 5'-AMP-treated mice overlapped with the same genes in the testis of ob/ob mice, and these genes belonged to the clusters of steroid metabolic process and regulation of hormone levels, respectively. Serum testosterone was reduced in ob/ob and 5'-AMP-treated mice. Metabolomic analysis based on 1 H nuclear magnetic resonance showed that the testicular metabolic profiles of ob/ob mice were similar to those of 5'-AMP treated mice. Exogenous 5'-AMP inhibited the phosphorylation of AKT and mammalian target of rapamycin signal transduction and reduced the proliferating cell nuclear antigen expressions in testes. Our results suggest that the accumulation of adenosine causes metabolic disorders in testes and associates lower testosterone level in obese mice.
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Affiliation(s)
- Xiao Yang
- Center for Molecular Metabolism, Nanjing University of Science and Technology, Nanjing, China
| | - Yang Zhao
- Center for Molecular Metabolism, Nanjing University of Science and Technology, Nanjing, China
| | - Qi Sun
- Center for Molecular Metabolism, Nanjing University of Science and Technology, Nanjing, China
| | - Yunxia Yang
- Center for Molecular Metabolism, Nanjing University of Science and Technology, Nanjing, China
| | - Yan Gao
- Center for Molecular Metabolism, Nanjing University of Science and Technology, Nanjing, China
| | - Wenhao Ge
- Center for Molecular Metabolism, Nanjing University of Science and Technology, Nanjing, China
| | - Junhao Liu
- Center for Molecular Metabolism, Nanjing University of Science and Technology, Nanjing, China
| | - Xi Xu
- Center for Molecular Metabolism, Nanjing University of Science and Technology, Nanjing, China
| | - Jianfa Zhang
- Center for Molecular Metabolism, Nanjing University of Science and Technology, Nanjing, China
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11
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Shao M, Zhao Y, Liu Y, Yang T, Xu M, Zhang X, Rao Z. Intracellular Environment Improvement of Mycobacterium neoaurum for Enhancing Androst-1,4-Diene-3,17-Dione Production by Manipulating NADH and Reactive Oxygen Species Levels. Molecules 2019; 24:E3841. [PMID: 31731395 PMCID: PMC6864555 DOI: 10.3390/molecules24213841] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 10/14/2019] [Accepted: 10/20/2019] [Indexed: 01/27/2023] Open
Abstract
As one of the most significant steroid hormone precursors, androst-1,4-diene-3,17-dione (ADD) could be used to synthesize many valuable hormone drugs. The microbial transformation of sterols to ADD has received extensive attention in recent years. In a previous study, Mycobacterium neoaurum JC-12 was isolated and converted sterols to the major product, ADD. In this work, we enhanced ADD yield by improving the cell intracellular environment. First, we introduced a nicotinamide adenine dinucleotide (NADH) oxidase from Bacillus subtilis to balance the intracellular NAD+ availability in order to strengthen the ADD yield. Then, the catalase gene from M. neoaurum was also over-expressed to simultaneously scavenge the generated H2O2 and eliminate its toxic effects on cell growth and sterol transformation. Finally, using a 5 L fermentor, the recombinant strain JC-12yodC-katA produced 9.66 g/L ADD, which increased by 80% when compared with the parent strain. This work shows a promising way to increase the sterol transformation efficiency by regulating the intracellular environment.
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Affiliation(s)
- Minglong Shao
- The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (M.S.); (T.Y.); (M.X.); (X.Z.)
| | - Youxi Zhao
- Beijing Key Laboratory of Biomass Waste Resource Utilization, College of Biochemical Engineering, Beijing Union University, Beijing 10023, China;
| | - Yu Liu
- The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (M.S.); (T.Y.); (M.X.); (X.Z.)
| | - Taowei Yang
- The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (M.S.); (T.Y.); (M.X.); (X.Z.)
| | - Meijuan Xu
- The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (M.S.); (T.Y.); (M.X.); (X.Z.)
| | - Xian Zhang
- The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (M.S.); (T.Y.); (M.X.); (X.Z.)
| | - Zhiming Rao
- The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (M.S.); (T.Y.); (M.X.); (X.Z.)
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12
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Metabolic Effects of Dietary Glycerol Supplementation in Muscle and Liver of European Seabass and Rainbow Trout by 1H NMR Metabolomics. Metabolites 2019; 9:metabo9100202. [PMID: 31569727 PMCID: PMC6835518 DOI: 10.3390/metabo9100202] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/20/2019] [Accepted: 09/22/2019] [Indexed: 12/17/2022] Open
Abstract
The sustainable growth of fish aquaculture will require the procurement of non-marine feed sources. Glycerol is a potential feed supplement whose metabolism may spare the catabolism of dietary amino acids, thereby extending the use of the feed protein to other physiological functions such as growth. In the present study, the effects of dietary glycerol supplementation on the muscle and liver metabolomes of rainbow trout (Oncorhynchus mykiss) and European seabass (Dicentrarchus labrax) were evaluated. Fish juveniles were fed diets with 0%, 2.5%, and 5% glycerol. Muscle and liver aqueous fractions were extracted and 1H NMR spectra were acquired. Metabolite profiles derived from the 1H NMR signals were assessed using univariate and multivariate statistical analyses. The adenylate energy charge was determined in the muscle. For both species, the muscle metabolite profile showed more variability compared to that of the liver and was most perturbed by the 5.0% glycerol diet. For the liver metabolite profile, rainbow trout showed fewer differences compared to European seabass. No differences were observed in energy charge between experimental groups for either species. Thus, rainbow trout appeared to be less susceptible to tissue metabolite perturbations, compared to seabass, when the diet was supplemented with up to 5% glycerol.
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13
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Bugaj O, Zieliński J, Kusy K, Kantanista A, Wieliński D, Guzik P. The Effect of Exercise on the Skin Content of the Reduced Form of NAD and Its Response to Transient Ischemia and Reperfusion in Highly Trained Athletes. Front Physiol 2019; 10:600. [PMID: 31156467 PMCID: PMC6529559 DOI: 10.3389/fphys.2019.00600] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 04/26/2019] [Indexed: 12/22/2022] Open
Abstract
Reduced nicotinamide adenine dinucleotide (NADH) is synthesized in the cellular nucleus, cytoplasm and mitochondria but oxidized into NAD+ almost exclusively in mitochondria. Activation of human skin by the 340 nm ultraviolet light triggers natural fluorescence at the light length of 460 nm, which intensity is proportional to the skin NADH content. This phenomenon is used by the Flow Mediated Skin Fluorescence (FMSF) which measures changes in the skin NADH content during transient ischemia and reperfusion. We examined the effects of exercise to exhaustion on the skin changes of NADH in response to 200 s forearm ischemia and reperfusion in 121 highly trained athletes (94 men and 27 women, long-distance running, triathlon, taekwondo, rowing, futsal, sprint running, fencing, and tennis). We found that exercise until exhaustion changes the skin content of NADH, modifies NADH turnover at rest, during ischemia and reperfusion in the most superficial living skin cells. Compared to the pre-exercise, there were significant increases in: mean fluorescence recorded during rest as the baseline value (B mean) (p < 0.001), the maximal fluorescence that increased above the baseline during controlled forearm ischemia (FImax) (p < 0.001, only in men), the minimal fluorescence after decreasing below the baseline during reperfusion (FRmin) (p < 0.001 men; p < 0.01 women) and the difference between B mean and FRmin (R min) (p < 0.01), and reductions in the difference between FImax and B mean (I max) (p < 0.001) and I max/IRampl ratio (CImax) (p < 0.001) after the incremental exercise test. There was no statistical difference between pre- and post-exercise the maximal range of the fluorescence change during ischemia and reperfusion (IRampl). In conclusion, exercise to exhaustion modifies the skin NADH content at rest, during ischemia and reperfusion as well as the magnitude of changes in the NADH caused by ischemia and reperfusion. Our findings suggest that metabolic changes in the skin NADH accompanying exercise extend beyond muscles and affect other cells and organs.
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Affiliation(s)
- Olga Bugaj
- Department of Athletics, Strength and Conditioning, Poznań University of Physical Education, Poznań, Poland
| | - Jacek Zieliński
- Department of Athletics, Strength and Conditioning, Poznań University of Physical Education, Poznań, Poland
| | - Krzysztof Kusy
- Department of Athletics, Strength and Conditioning, Poznań University of Physical Education, Poznań, Poland
| | - Adam Kantanista
- Department of Sport Kinesiology, Poznań University of Physical Education, Poznań, Poland
| | - Dariusz Wieliński
- Department of Anthropology and Biometry, Poznań University of Physical Education, Poznań, Poland
| | - Przemysław Guzik
- Department of Cardiology-Intensive Therapy, Poznań University of Medical Sciences, Poznań, Poland
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14
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Cao S, Wang L, Zhang Z, Chen F, Wu Q, Li L. Sulforaphane-induced metabolomic responses with epigenetic changes in estrogen receptor positive breast cancer cells. FEBS Open Bio 2018; 8:2022-2034. [PMID: 30524952 PMCID: PMC6275259 DOI: 10.1002/2211-5463.12543] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 10/09/2018] [Accepted: 10/19/2018] [Indexed: 12/21/2022] Open
Abstract
Estrogen is a risk factor for breast cancer. The isothiocyanate sulforaphane (SFN), found in cruciferous vegetables, has been identified as an effective chemopreventive agent, and may prevent or treat breast cancer by reversing estrogen‐induced metabolic changes. Here, we investigated metabolic changes in estrogen receptor‐positive breast cancer (MCF‐7) cells treated with estradiol (E2) and/or SFN to identify key metabolite panels that might provide new insights into the underlying mechanisms of the antitumor effects of SFN. Gas chromatography–mass spectrometry and ultra performance liquid chromatography–mass spectrometry (UPLC‐Orbitrap‐MS) were used to obtain the metabolic profiles of MCF‐7 cells. The data were analyzed using Student's t‐test and multivariate statistics, including principal component analysis and partial least squares discriminant analysis. Hydroxymethylation was detected by UPLC‐Orbitrap‐MS and verified by immunofluorescence assay. We report that significant changes in metabolites induced by E2 and SFN were associated with differences in glycolysis and energy metabolism, and also amino acid, purine, and folic acid metabolism. E2 may alter methylation and hydroxymethylation status via the folic acid pathway. We also identified biomarkers that may be of use in interpretation of the metabolic pathways evoked by the effects of E2 and SFN on breast cancer cells. The identified biomarkers associated with metabolic pathways provide new insight into the chemopreventive mechanisms of SFN.
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Affiliation(s)
- Shuyuan Cao
- Department of Hygienic Analysis and Detection and Ministry of Education Key Lab for Modern Toxicology School of Public Health Nanjing Medical University China
| | - Li Wang
- Department of Hygienic Analysis and Detection and Ministry of Education Key Lab for Modern Toxicology School of Public Health Nanjing Medical University China
| | - Zhan Zhang
- Department of Hygienic Analysis and Detection and Ministry of Education Key Lab for Modern Toxicology School of Public Health Nanjing Medical University China
| | - Feng Chen
- Department of Epidemiology and Biostatistics and Ministry of Education Key Lab for Modern Toxicology School of Public Health Nanjing Medical University China
| | - Qian Wu
- Department of Hygienic Analysis and Detection and Ministry of Education Key Lab for Modern Toxicology School of Public Health Nanjing Medical University China
| | - Lei Li
- Department of Hygienic Analysis and Detection and Ministry of Education Key Lab for Modern Toxicology School of Public Health Nanjing Medical University China
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15
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Chen AP, Lau AZ, Gu YP, Schroeder MA, Barry J, Cunningham CH. Probing the cardiac malate-aspartate shuttle non-invasively using hyperpolarized [1,2- 13 C 2 ]pyruvate. NMR IN BIOMEDICINE 2018; 31:e3845. [PMID: 29106770 DOI: 10.1002/nbm.3845] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/18/2017] [Accepted: 09/20/2017] [Indexed: 06/07/2023]
Abstract
Previous studies have demonstrated that using hyperpolarized [2-13 C]pyruvate as a contrast agent can reveal 13 C signals from metabolites associated with the tricarboxylic acid (TCA) cycle. However, the metabolites detectable from TCA cycle-mediated oxidation of [2-13 C]pyruvate are the result of several metabolic steps. In the instance of the [5-13 C]glutamate signal, the amplitude can be modulated by changes to the rates of pyruvate dehydrogenase (PDH) flux, TCA cycle flux and metabolite pool size. Also key is the malate-aspartate shuttle, which facilitates the transport of cytosolic reducing equivalents into the mitochondria for oxidation via the malate-α-ketoglutarate transporter, a process coupled to the exchange of cytosolic malate for mitochondrial α-ketoglutarate. In this study, we investigated the mechanism driving the observed changes to hyperpolarized [2-13 C]pyruvate metabolism. Using hyperpolarized [1,2-13 C]pyruvate with magnetic resonance spectroscopy (MRS) in the porcine heart with different workloads, it was possible to probe 13 C-glutamate labeling relative to rates of cytosolic metabolism, PDH flux and TCA cycle turnover in a single experiment non-invasively. Via the [1-13 C]pyruvate label, we observed more than a five-fold increase in the cytosolic conversion of pyruvate to [1-13 C]lactate and [1-13 C]alanine with higher workload. 13 C-Bicarbonate production by PDH was increased by a factor of 2.2. Cardiac cine imaging measured a two-fold increase in cardiac output, which is known to couple to TCA cycle turnover. Via the [2-13 C]pyruvate label, we observed that 13 C-acetylcarnitine production increased 2.5-fold in proportion to the 13 C-bicarbonate signal, whereas the 13 C-glutamate metabolic flux remained constant on adrenergic activation. Thus, the 13 C-glutamate signal relative to the amount of 13 C-labeled acetyl-coenzyme A (acetyl-CoA) entering the TCA cycle was decreased by 40%. The data strongly suggest that NADH (reduced form of nicotinamide adenine dinucleotide) shuttling from the cytosol to the mitochondria via the malate-aspartate shuttle is limited on adrenergic activation. Changes in [5-13 C]glutamate production from [2-13 C]pyruvate may play an important future role in non-invasive myocardial assessment in patients with cardiovascular diseases, but careful interpretation of the results is required.
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Affiliation(s)
| | - Angus Z Lau
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Yi-Ping Gu
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Marie A Schroeder
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Jennifer Barry
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Charles H Cunningham
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
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16
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Mazzone M, Menga A, Castegna A. Metabolism and TAM functions-it takes two to tango. FEBS J 2017; 285:700-716. [DOI: 10.1111/febs.14295] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/25/2017] [Accepted: 10/17/2017] [Indexed: 12/16/2022]
Affiliation(s)
- Massimiliano Mazzone
- Laboratory of Tumor Inflammation and Angiogenesis; Center for Cancer Biology (CCB); VIB; Leuven Belgium
- Laboratory of Tumor Inflammation and Angiogenesis; Department of Oncology; KU Leuven; Belgium
| | - Alessio Menga
- Hematology Unit; National Cancer Research Center; Istituto Tumori ‘Giovanni Paolo II’; Bari Italy
| | - Alessandra Castegna
- Hematology Unit; National Cancer Research Center; Istituto Tumori ‘Giovanni Paolo II’; Bari Italy
- Department of Biosciences, Biotechnologies and Biopharmaceutics; University of Bari; Italy
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17
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Gormsen LC, Svart M, Thomsen HH, Søndergaard E, Vendelbo MH, Christensen N, Tolbod LP, Harms HJ, Nielsen R, Wiggers H, Jessen N, Hansen J, Bøtker HE, Møller N. Ketone Body Infusion With 3-Hydroxybutyrate Reduces Myocardial Glucose Uptake and Increases Blood Flow in Humans: A Positron Emission Tomography Study. J Am Heart Assoc 2017; 6:JAHA.116.005066. [PMID: 28242634 PMCID: PMC5524028 DOI: 10.1161/jaha.116.005066] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND High levels of ketone bodies are associated with improved survival as observed with regular exercise, caloric restriction, and-most recently-treatment with sodium-glucose linked transporter 2 inhibitor antidiabetic drugs. In heart failure, indices of ketone body metabolism are upregulated, which may improve energy efficiency and increase blood flow in skeletal muscle and the kidneys. Nevertheless, it is uncertain how ketone bodies affect myocardial glucose uptake and blood flow in humans. Our study was therefore designed to test whether ketone body administration in humans reduces myocardial glucose uptake (MGU) and increases myocardial blood flow. METHODS AND RESULTS Eight healthy subjects, median aged 60 were randomly studied twice: (1) During 390 minutes infusion of Na-3-hydroxybutyrate (KETONE) or (2) during 390 minutes infusion of saline (SALINE), together with a concomitant low-dose hyperinsulinemic-euglycemic clamp to inhibit endogenous ketogenesis. Myocardial blood flow was measured by 15O-H2O positron emission tomography/computed tomography, myocardial fatty acid metabolism by 11C-palmitate positron emission tomography/computed tomography and MGU by 18F-fluorodeoxyglucose positron emission tomography/computed tomography. Similar euglycemia, hyperinsulinemia, and suppressed free fatty acids levels were recorded on both study days; Na-3-hydroxybutyrate infusion increased circulating Na-3-hydroxybutyrate levels from zero to 3.8±0.5 mmol/L. MGU was halved by hyperketonemia (MGU [nmol/g per minute]: 304±97 [SALINE] versus 156±62 [KETONE], P<0.01), whereas no effects were observed on palmitate uptake oxidation or esterification. Hyperketonemia increased heart rate by ≈25% and myocardial blood flow by 75%. CONCLUSIONS Ketone bodies displace MGU and increase myocardial blood flow in healthy humans; these novel observations suggest that ketone bodies are important cardiac fuels and vasodilators, which may have therapeutic potentials.
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Affiliation(s)
- Lars C Gormsen
- Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Mads Svart
- Department of Endocrinology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Esben Søndergaard
- Department of Endocrinology, Aarhus University Hospital, Aarhus, Denmark
| | - Mikkel H Vendelbo
- Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Nana Christensen
- Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Lars Poulsen Tolbod
- Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Hendrik Johannes Harms
- Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Roni Nielsen
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
| | - Henrik Wiggers
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
| | - Niels Jessen
- Department of Clinical Pharmacology, Aarhus University Hospital, Aarhus, Denmark
| | - Jakob Hansen
- Department of Forensic Medicine, Aarhus University, Aarhus, Denmark
| | - Hans Erik Bøtker
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
| | - Niels Møller
- Department of Endocrinology, Aarhus University Hospital, Aarhus, Denmark
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18
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Imaging oxygen metabolism with hyperpolarized magnetic resonance: a novel approach for the examination of cardiac and renal function. Biosci Rep 2017; 37:BSR20160186. [PMID: 27899435 PMCID: PMC5270319 DOI: 10.1042/bsr20160186] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 11/28/2016] [Accepted: 11/29/2016] [Indexed: 12/24/2022] Open
Abstract
Every tissue in the body critically depends on meeting its energetic demands with sufficient oxygen supply. Oxygen supply/demand imbalances underlie the diseases that inflict the greatest socio-economic burden globally. The purpose of this review is to examine how hyperpolarized contrast media, used in combination with MR data acquisition methods, may advance our ability to assess oxygen metabolism non-invasively and thus improve management of clinical disease. We first introduce the concept of hyperpolarization and how hyperpolarized contrast media have been practically implemented to achieve translational and clinical research. We will then analyse how incorporating hyperpolarized contrast media could enable realization of unmet technical needs in clinical practice. We will focus on imaging cardiac and renal oxygen metabolism, as both organs have unique physiological demands to satisfy their requirements for tissue oxygenation, their dysfunction plays a fundamental role in society’s most prevalent diseases, and each organ presents unique imaging challenges. It is our aim that this review attracts a multi-disciplinary audience and sparks collaborations that utilize an exciting, emergent technology to advance our ability to treat patients adversely affected by an oxygen supply/demand mismatch.
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19
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Chen YJ, Mahieu NG, Huang X, Singh M, Crawford PA, Johnson SL, Gross RW, Schaefer J, Patti GJ. Lactate metabolism is associated with mammalian mitochondria. Nat Chem Biol 2016; 12:937-943. [PMID: 27618187 PMCID: PMC5069139 DOI: 10.1038/nchembio.2172] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 06/16/2016] [Indexed: 01/06/2023]
Abstract
It is well established that lactate secreted by fermenting cells can be oxidized or used as a gluconeogenic substrate by other cells and tissues. It is generally assumed, however, that within the fermenting cell itself, lactate is produced to replenish NAD+ and then is secreted. Here we explore the possibility that cytosolic lactate is metabolized by the mitochondria of fermenting mammalian cells. We found that fermenting HeLa and H460 cells utilize exogenous lactate carbon to synthesize a large percentage of their lipids. Using high-resolution mass spectrometry, we found that both 13C and 2-2H labels from enriched lactate enter the mitochondria. The lactate dehydrogenase (LDH) inhibitor oxamate decreased respiration of isolated mitochondria incubated in lactate, but not of isolated mitochondria incubated in pyruvate. Additionally, transmission electron microscopy (TEM) showed that LDHB localizes to the mitochondria. Taken together, our results demonstrate a link between lactate metabolism and the mitochondria of fermenting mammalian cells.
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Affiliation(s)
- Ying-Jr Chen
- Department of Chemistry, Washington University, St. Louis, Missouri, USA
| | - Nathaniel G Mahieu
- Department of Chemistry, Washington University, St. Louis, Missouri, USA
| | - Xiaojing Huang
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Manmilan Singh
- Department of Chemistry, Washington University, St. Louis, Missouri, USA
| | - Peter A Crawford
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Stephen L Johnson
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Richard W Gross
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jacob Schaefer
- Department of Chemistry, Washington University, St. Louis, Missouri, USA
| | - Gary J Patti
- Department of Chemistry, Washington University, St. Louis, Missouri, USA
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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20
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Meneses M, Bernardino R, Sá R, Silva J, Barros A, Sousa M, Silva B, Oliveira P, Alves M. Pioglitazone increases the glycolytic efficiency of human Sertoli cells with possible implications for spermatogenesis. Int J Biochem Cell Biol 2016; 79:52-60. [DOI: 10.1016/j.biocel.2016.08.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 08/03/2016] [Accepted: 08/07/2016] [Indexed: 12/22/2022]
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21
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Abstract
The heart is a biological pump that converts chemical to mechanical energy. This process of energy conversion is highly regulated to the extent that energy substrate metabolism matches energy use for contraction on a beat-to-beat basis. The biochemistry of cardiac metabolism includes the biochemistry of energy transfer, metabolic regulation, and transcriptional, translational as well as posttranslational control of enzymatic activities. Pathways of energy substrate metabolism in the heart are complex and dynamic, but all of them conform to the First Law of Thermodynamics. The perspectives expand on the overall idea that cardiac metabolism is inextricably linked to both physiology and molecular biology of the heart. The article ends with an outlook on emerging concepts of cardiac metabolism based on new molecular models and new analytical tools. © 2016 American Physiological Society. Compr Physiol 6:1675-1699, 2016.
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Affiliation(s)
- Heinrich Taegtmeyer
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston
| | - Truong Lam
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston
| | - Giovanni Davogustto
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston
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22
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Lau AZ, Miller JJ, Tyler DJ. Mapping of intracellular pH in the in vivo rodent heart using hyperpolarized [1-13C]pyruvate. Magn Reson Med 2016; 77:1810-1817. [PMID: 27173806 PMCID: PMC5412837 DOI: 10.1002/mrm.26260] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/14/2016] [Accepted: 04/06/2016] [Indexed: 12/22/2022]
Abstract
Purpose To demonstrate the feasibility of mapping intracellular pH within the in vivo rodent heart. Alterations in cardiac acid‐base balance can lead to acute contractile depression and alterations in Ca2+ signaling. The transient reduction in adenosine triphosphate (ATP) consumption and cardiac contractility may be initially beneficial; however, sustained pH changes can be maladaptive, leading to myocardial damage and electrical arrhythmias. Methods Spectrally selective radiofrequency (RF) pulses were used to excite the
HCO3− and CO2 resonances individually while preserving signal from the injected hyperpolarized [1‐13C]pyruvate. The large flip angle pulses were placed within a three‐dimensional (3D) imaging acquisition, which exploited CA‐mediated label exchange between
HCO3− and CO2. Images at 4.5 × 4.5 × 5 mm3 resolution were obtained in the in vivo rodent heart. The technique was evaluated in healthy rodents scanned at baseline and during high cardiac workload induced by dobutamine infusion. Results The intracellular pH was measured to be 7.15 ± 0.04 at baseline, and decreased to 6.90 ± 0.06 following 15 min of continuous β‐adrenergic stimulation. Conclusions Volumetric maps of intracellular pH can be obtained following an injection of hyperpolarized [1‐13C]pyruvate. The new method is anticipated to enable assessment of stress‐inducible ischemia and potential ventricular arrythmogenic substrates within the ischemic heart. Magn Reson Med 77:1810–1817, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Angus Z Lau
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, UK.,Department of Physiology, Anatomy, and Genetics, University of Oxford, UK
| | - Jack J Miller
- Department of Physiology, Anatomy, and Genetics, University of Oxford, UK.,Department of Physics, Clarendon Laboratory, University of Oxford, UK
| | - Damian J Tyler
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, UK.,Department of Physiology, Anatomy, and Genetics, University of Oxford, UK
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23
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Taegtmeyer H, Young ME, Lopaschuk GD, Abel ED, Brunengraber H, Darley-Usmar V, Des Rosiers C, Gerszten R, Glatz JF, Griffin JL, Gropler RJ, Holzhuetter HG, Kizer JR, Lewandowski ED, Malloy CR, Neubauer S, Peterson LR, Portman MA, Recchia FA, Van Eyk JE, Wang TJ. Assessing Cardiac Metabolism: A Scientific Statement From the American Heart Association. Circ Res 2016; 118:1659-701. [PMID: 27012580 DOI: 10.1161/res.0000000000000097] [Citation(s) in RCA: 185] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In a complex system of interrelated reactions, the heart converts chemical energy to mechanical energy. Energy transfer is achieved through coordinated activation of enzymes, ion channels, and contractile elements, as well as structural and membrane proteins. The heart's needs for energy are difficult to overestimate. At a time when the cardiovascular research community is discovering a plethora of new molecular methods to assess cardiac metabolism, the methods remain scattered in the literature. The present statement on "Assessing Cardiac Metabolism" seeks to provide a collective and curated resource on methods and models used to investigate established and emerging aspects of cardiac metabolism. Some of those methods are refinements of classic biochemical tools, whereas most others are recent additions from the powerful tools of molecular biology. The aim of this statement is to be useful to many and to do justice to a dynamic field of great complexity.
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Fluctuations in Cytosolic Calcium Regulate the Neuronal Malate-Aspartate NADH Shuttle: Implications for Neuronal Energy Metabolism. Neurochem Res 2015; 40:2425-30. [PMID: 26138554 DOI: 10.1007/s11064-015-1652-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/15/2015] [Accepted: 06/23/2015] [Indexed: 12/21/2022]
Abstract
The malate-aspartate NADH shuttle (MAS) operates in neurons and other cells to translocate reducing equivalents from the cytosol to the mitochondrial matrix, thus allowing a continued flux through the glycolytic pathway and metabolism of extracellular lactate. Recent discoveries have taught us that MAS is regulated by fluctuations in cytosolic Ca(2+) levels, and that this regulation is required to maintain a tight coupling between neuronal activity and mitochondrial respiration and oxidative phosphorylation. At cytosolic Ca(2+) fluctuations below the threshold of the mitochondrial calcium uniporter, there is a positive correlation between Ca(2+) and MAS activity; however, if cytosolic Ca(2+) increases above the threshold, MAS activity is thought to be reduced by an intricate mechanism. The latter forces the neurons to partly rely on anaerobic glycolysis producing lactate that may be metabolized subsequently, by neurons or other cells. In this review, we will discuss the evidence for Ca(2+)-mediated regulation of MAS that have been uncovered over the last decade or so, together with the need for further verification, and examine the metabolic ramifications for neurons.
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Leptin modulates human Sertoli cells acetate production and glycolytic profile: a novel mechanism of obesity-induced male infertility? Biochim Biophys Acta Mol Basis Dis 2015; 1852:1824-32. [PMID: 26071642 DOI: 10.1016/j.bbadis.2015.06.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 05/20/2015] [Accepted: 06/08/2015] [Indexed: 12/31/2022]
Abstract
Human feeding behavior and lifestyle are gradually being altered, favoring the development of metabolic diseases, particularly type 2 diabetes and obesity. Leptin is produced by the adipose tissue acting as a satiety signal. Its levels have been positively correlated with fat mass and hyperleptinemia has been proposed to negatively affect male reproductive function. Nevertheless, the molecular mechanisms by which this hormone affects male fertility remain unknown. Herein, we hypothesize that leptin acts on human Sertoli cells (hSCs), the "nurse cells" of spermatogenesis, altering their metabolism. To test our hypothesis, hSCs were cultured without or with leptin (5, 25 and 50ng/mL). Leptin receptor was identified by qPCR and Western blot. Protein levels of glucose transporters (GLUT1, GLUT2 and GLUT3), phosphofructokinase, lactate dehydrogenase (LDH) and monocarboxylate transporter 4 (MCT4) were determined by Western Blot. LDH activity was assessed and metabolite production/consumption determined by proton nuclear magnetic resonance. Oxidative damage was evaluated by assessing lipid peroxidation, protein carbonilation and nitration. Our data shows that leptin receptor is expressed in hSCs. The concentration of leptin found in lean, healthy patients, upregulated GLUT2 protein levels and concentrations of leptin found in lean and obese patients increased LDH activity. Of note, all leptin concentrations decreased hSCs acetate production illustrating a novel mechanism for this hormone action. Moreover, our data shows that leptin does not induce or protect hSCs from oxidative damage. We report that this hormone modulates the nutritional support of spermatogenesis, illustrating a novel mechanism that may be linked to obesity-induced male infertility.
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Daily consumption of white tea (Camellia sinensis (L.)) improves the cerebral cortex metabolic and oxidative profile in prediabetic Wistar rats. Br J Nutr 2015; 113:832-42. [PMID: 25716141 DOI: 10.1017/s0007114514004395] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Diabetes mellitus (DM) is a major public health problem and its incidence is rising dramatically. The brain, particularly the cerebral cortex, is very susceptible to glucose fluctuations and hyperglycaemia-induced oxidative stress. Tea (Camellia sinensis (L.)) is widely consumed; however, the antidiabetic properties of white tea remain largely unexplored. In the present study, we investigated the effects of daily consumption of white tea on the cerebral cortex of prediabetic rats. The cerebral cortex metabolic profile was evaluated, and the expression levels of GLUT, phosphofructokinase-1, lactate dehydrogenase (LDH) and monocarboxylate transporter 4 were assessed. LDH activity was also determined. The cerebral cortex oxidative profile was determined by evaluating its antioxidant power, lipid peroxidation and protein oxidation levels. Catalase, glutathione, glutamate, N-acetylaspartate, aspartate, choline, γ-aminobutyric acid, taurine and valine contents were determined. Daily consumption of white tea ameliorated glucose tolerance and insulin sensitivity. Moreover, white tea altered the cortex glycolytic profile, modulating GLUT expression and lactate and alanine contents. Finally, white tea consumption restored protein oxidation and lipid peroxidation levels and catalase expression, and improved antioxidant capacity. In conclusion, daily consumption of white tea improved the cerebral cortex metabolic and oxidative profile in prediabetic rats, suggesting it as a good, safe and inexpensive strategy to prevent DM-related effects in the cerebral cortex.
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Rato L, Alves MG, Dias TR, Cavaco JE, Oliveira PF. Testicular Metabolic Reprogramming in Neonatal Streptozotocin-Induced Type 2 Diabetic Rats Impairs Glycolytic Flux and Promotes Glycogen Synthesis. J Diabetes Res 2015; 2015:973142. [PMID: 26064993 PMCID: PMC4443934 DOI: 10.1155/2015/973142] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 04/22/2015] [Accepted: 04/23/2015] [Indexed: 12/25/2022] Open
Abstract
Defects in testicular metabolism are directly implicated with male infertility, but most of the mechanisms associated with type 2 diabetes- (T2DM) induced male infertility remain unknown. We aimed to evaluate the effects of T2DM on testicular glucose metabolism by using a neonatal-streptozotocin- (n-STZ) T2DM animal model. Plasma and testicular hormonal levels were evaluated using specific kits. mRNA and protein expression levels were assessed by real-time PCR and Western Blot, respectively. Testicular metabolic profile was assessed by (1)H-NMR spectroscopy. T2DM rats showed increased glycemic levels, impaired glucose tolerance and hyperinsulinemia. Both testicular and serum testosterone levels were decreased, whereas those of 17β-estradiol were not altered. Testicular glycolytic flux was not favored in testicles of T2DM rats, since, despite the increased expression of both glucose transporters 1 and 3 and the enzyme phosphofructokinase 1, lactate dehydrogenase activity was severely decreased contributing to lower testicular lactate content. However, T2DM enhanced testicular glycogen accumulation, by modulating the availability of the precursors for its synthesis. T2DM also affected the reproductive sperm parameters. Taken together these results indicate that T2DM is able to reprogram testicular metabolism by enhancing alternative metabolic pathways, particularly glycogen synthesis, and such alterations are associated with impaired sperm parameters.
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Affiliation(s)
- L. Rato
- Health Sciences Research Centre (CICS), Faculty of Health Sciences, University of Beira Interior (UBI), Covilhã, Portugal
| | - M. G. Alves
- Health Sciences Research Centre (CICS), Faculty of Health Sciences, University of Beira Interior (UBI), Covilhã, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology and Center for Neurosciences and Cell Biology (CNC), University of Coimbra, Portugal
| | - T. R. Dias
- Health Sciences Research Centre (CICS), Faculty of Health Sciences, University of Beira Interior (UBI), Covilhã, Portugal
| | - J. E. Cavaco
- Health Sciences Research Centre (CICS), Faculty of Health Sciences, University of Beira Interior (UBI), Covilhã, Portugal
| | - Pedro F. Oliveira
- Health Sciences Research Centre (CICS), Faculty of Health Sciences, University of Beira Interior (UBI), Covilhã, Portugal
- Department of Microscopy, Laboratory of Cell Biology, Abel Salazar Institute of Biomedical Sciences (ICBAS), University of Porto, Portugal
- Unit for Multidisciplinary Research in Biomedicine (UMIB), Abel Salazar Institute of Biomedical Sciences (ICBAS), University of Porto (UP), Portugal
- *Pedro F. Oliveira:
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Kane DA. Lactate oxidation at the mitochondria: a lactate-malate-aspartate shuttle at work. Front Neurosci 2014; 8:366. [PMID: 25505376 PMCID: PMC4243568 DOI: 10.3389/fnins.2014.00366] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/25/2014] [Indexed: 11/30/2022] Open
Abstract
Lactate, the conjugate base of lactic acid occurring in aqueous biological fluids, has been derided as a “dead-end” waste product of anaerobic metabolism. Catalyzed by the near-equilibrium enzyme lactate dehydrogenase (LDH), the reduction of pyruvate to lactate is thought to serve to regenerate the NAD+ necessary for continued glycolytic flux. Reaction kinetics for LDH imply that lactate oxidation is rarely favored in the tissues of its own production. However, a substantial body of research directly contradicts any notion that LDH invariably operates unidirectionally in vivo. In the current Perspective, a model is forwarded in which the continuous formation and oxidation of lactate serves as a mitochondrial electron shuttle, whereby lactate generated in the cytosol of the cell is oxidized at the mitochondria of the same cell. From this perspective, an intracellular lactate shuttle operates much like the malate-aspartate shuttle (MAS); it is also proposed that the two shuttles are necessarily interconnected in a lactate-MAS. Among the requisite features of such a model, significant compartmentalization of LDH, much like the creatine kinase of the phosphocreatine shuttle, would facilitate net cellular lactate oxidation in a variety of cell types.
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Affiliation(s)
- Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University Antigonish, NS, Canada
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Banke NH, Lewandowski ED. Impaired cytosolic NADH shuttling and elevated UCP3 contribute to inefficient citric acid cycle flux support of postischemic cardiac work in diabetic hearts. J Mol Cell Cardiol 2014; 79:13-20. [PMID: 25450611 DOI: 10.1016/j.yjmcc.2014.10.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/18/2014] [Accepted: 10/28/2014] [Indexed: 10/24/2022]
Abstract
Diabetic hearts are subject to more extensive ischemia/reperfusion (ISC/REP) damage. This study examined the efficiency of citric acid cycle (CAC) flux and the transfer of cytosolic reducing equivalents into the mitochondria for oxidative support of cardiac work following ISC/REP in hearts of c57bl/6 (NORM) and type 2 diabetic, db/db mouse hearts. Flux through the CAC and malate-aspartate shuttle (MA) were monitored via dynamic (13)C NMR of isolated hearts perfused with (13)C palmitate+glucose. MA flux was lower in db/db than NORM. Oxoglutarate malate carrier (OMC) was elevated in the db/db heart, suggesting a compensatory response to low NADHc. Baseline CAC flux per unit work (rate-pressure-product, RPP) was similar between NORM and db/db, but ISC/REP reduced the efficiency of CAC flux/RPP by 20% in db/db. ISC/REP also increased UCP3 transcription, indicating potential for greater uncoupling. Therefore, ISC/REP induces inefficient carbon utilization through the CAC in hearts of diabetic mice due to the combined inefficiencies in NADHc transfer per OMC content and increased uncoupling via UCP3. Ischemia and reperfusion exacerbated pre-existing mitochondrial defects and metabolic limitations in the cytosol of diabetic hearts. These limitations and defects render diabetic hearts more susceptible to inefficient carbon fuel utilization for oxidative energy metabolism.
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Affiliation(s)
- Natasha H Banke
- Center for Cardiovascular Research and Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine, Chicago, IL 60612, USA
| | - E Douglas Lewandowski
- Center for Cardiovascular Research and Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine, Chicago, IL 60612, USA.
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Alves MG, Martins AD, Vaz CV, Correia S, Moreira PI, Oliveira PF, Socorro S. Metformin and male reproduction: effects on Sertoli cell metabolism. Br J Pharmacol 2014; 171:1033-42. [PMID: 24261663 DOI: 10.1111/bph.12522] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 11/04/2013] [Accepted: 11/18/2013] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Metformin is commonly used to treat type 2 diabetes (T2D). While new clinical applications have been ascribed to metformin, including treatment of anovulatory infertility, its effects on male reproduction have not been investigated. The Sertoli cell (SC) is crucial for germ cell development, exerting metabolic control of spermatogenesis, therefore, we investigated the effects of metformin on SC metabolism. EXPERIMENTAL APPROACH Rat SCs were cultured in the absence and presence of metformin (5, 50 and 500 μM). mRNA and protein levels of glucose transporters (GLUT1 and GLUT3), phosphofructokinase 1 (PFK 1), lactate dehydrogenase (LDH) and monocarboxylate transporter 4 (MCT4) were determined by quantitative PCR and Western blot respectively. LDH activity was assessed and metabolite production/consumption determined by (1) H-NMR. KEY RESULTS Metformin (50 μM) decreased mRNA and protein levels of GLUT1, GLUT3, MCT4 and PFK 1 but did not affect LDH mRNA or protein levels. However, although glucose consumption was maintained in metformin-treated cells, LDH activity, lactate and alanine production were increased, indicating an enhanced glycolytic flux. No metabolic cytotoxicity was detected in SCs exposed to supra-pharmacological concentration of metformin. CONCLUSIONS AND IMPLICATIONS Our results indicate that metformin: (i) decreases mRNA and protein levels of glycolysis-related transporters in SCs but increases their activity; and (ii) stimulates alanine production, which induces antioxidant activity and maintains the NADH/NAD(+) equilibrium. The increased lactate in metformin-treated SCs provides nutritional support and has an anti-apoptotic effect in developing germ cells. Thus, metformin can be considered as a suitable antidiabetic drug for male patients of reproductive age with T2D.
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Affiliation(s)
- M G Alves
- CICS-UBI - Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
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Rocha CS, Martins AD, Rato L, Silva BM, Oliveira PF, Alves MG. Melatonin alters the glycolytic profile of Sertoli cells: implications for male fertility. Mol Hum Reprod 2014; 20:1067-76. [PMID: 25205674 DOI: 10.1093/molehr/gau080] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Melatonin co-operates with insulin in the regulation of glucose homeostasis. Within the testis, glucose metabolism in the somatic Sertoli cells (SCs) is pivotal for spermatogenesis. Since the effects of melatonin on male reproductive physiology remain largely unknown, we hypothesized that melatonin may affect spermatogenesis by modulating SC metabolism, interacting with insulin. To test our hypothesis, rat SCs were maintained in culture for 24 h in the presence of insulin, melatonin or both and metabolite production/consumption was determined by proton nuclear magnetic resonance ((1)H-NMR). Protein levels of glucose transporters (GLUT1 and GLUT3), phosphofructokinase 1, lactate dehydrogenase (LDH) and monocarboxylate transporter 4 were determined by western blot. LDH activity was also assessed. SCs treated with melatonin showed an increase in glucose consumption via modulation of GLUT1 levels, but decreased LDH protein expression and activity, which resulted in lower lactate production. Moreover, SCs exposed to melatonin produced and accumulated less acetate than insulin-exposed cells. The combined treatment (insulin plus melatonin) increased acetate production by SCs, but intracellular acetate content remained lower than in insulin exposed cells. Finally, the intracellular redox state, as reflected by intracellular lactate/alanine ratio, was maintained at control levels in SCs by melatonin exposure (i.e. melatonin, alone or with insulin, increased the lactate/alanine ratio versus cells treated with insulin). Furthermore, SCs exposed to insulin plus melatonin produced more lactate and maintained the protein levels of some glycolysis-related enzymes and transporters at control levels. These findings illustrate that melatonin regulates SCs metabolism, and thus may affect spermatogenesis. Since lactate produced by SCs provides nutritional support and has an anti-apoptotic effect in developing germ cells, melatonin supplementation may be an effective therapy for diabetic male individuals facing subfertility/infertility.
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Affiliation(s)
- Cátia S Rocha
- CICS-UBI, Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal
| | - Ana D Martins
- CICS-UBI, Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal
| | - Luís Rato
- CICS-UBI, Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal
| | - Branca M Silva
- CICS-UBI, Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal
| | - Pedro F Oliveira
- CICS-UBI, Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal
| | - Marco G Alves
- CICS-UBI, Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal
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Efficient whole-cell biocatalyst for acetoin production with NAD+ regeneration system through homologous co-expression of 2,3-butanediol dehydrogenase and NADH oxidase in engineered Bacillus subtilis. PLoS One 2014; 9:e102951. [PMID: 25036158 PMCID: PMC4103878 DOI: 10.1371/journal.pone.0102951] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 06/24/2014] [Indexed: 01/19/2023] Open
Abstract
Acetoin (3-hydroxy-2-butanone), an extensively-used food spice and bio-based platform chemical, is usually produced by chemical synthesis methods. With increasingly requirement of food security and environmental protection, bio-fermentation of acetoin by microorganisms has a great promising market. However, through metabolic engineering strategies, the mixed acid-butanediol fermentation metabolizes a certain portion of substrate to the by-products of organic acids such as lactic acid and acetic acid, which causes energy cost and increases the difficulty of product purification in downstream processes. In this work, due to the high efficiency of enzymatic reaction and excellent selectivity, a strategy for efficiently converting 2,3-butandiol to acetoin using whole-cell biocatalyst by engineered Bacillus subtilis is proposed. In this process, NAD+ plays a significant role on 2,3-butanediol and acetoin distribution, so the NADH oxidase and 2,3-butanediol dehydrogenase both from B. subtilis are co-expressed in B. subtilis 168 to construct an NAD+ regeneration system, which forces dramatic decrease of the intracellular NADH concentration (1.6 fold) and NADH/NAD+ ratio (2.2 fold). By optimization of the enzymatic reaction and applying repeated batch conversion, the whole-cell biocatalyst efficiently produced 91.8 g/L acetoin with a productivity of 2.30 g/(L·h), which was the highest record ever reported by biocatalysis. This work indicated that manipulation of the intracellular cofactor levels was more effective than the strategy of enhancing enzyme activity, and the bioprocess for NAD+ regeneration may also be a useful way for improving the productivity of NAD+-dependent chemistry-based products.
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Kailavasan M, Rehman I, Reynolds S, Bucur A, Tozer G, Paley M. NMR-based evaluation of the metabolic profile and response to dichloroacetate of human prostate cancer cells. NMR IN BIOMEDICINE 2014; 27:610-6. [PMID: 24639007 PMCID: PMC4260680 DOI: 10.1002/nbm.3101] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 02/17/2014] [Accepted: 02/17/2014] [Indexed: 05/16/2023]
Abstract
The aim of this study was to evaluate the metabolic profile of human prostate cancer cells that have different metastatic potential and to determine their response to dichloroacetate (DCA) using NMR technology. Two isogenic human prostate cancer cell lines, differing in their metastatic potential [LNCaP (poorly metastatic) and LNCaP-LN3 (highly metastatic)], were studied. Metabolite ratios from NMR spectral integrals acquired at a field strength of 9.4 T using a 5-mm broadband probe with an NMR-compatible bioreactor were compared in the presence and absence of the pyruvate dehydrogenase kinase inhibitor DCA. Lactate dehydrogenase (LDH) isoenzymes were assessed by zymography. Following the treatment of cells with 50 mm DCA, there was a significant reduction in the lactate/choline, lactate/creatine, lactate/alanine and the combined lactate/(choline + creatine + alanine) ratios in LNCaP-LN3 cells relative to LNCaP cells. No significant changes in metabolite ratios were found in LNCaP cells following DCA treatment. As expected, LDH zymography assays showed an absence of the LDH-B subunit in LNCaP-LN3 cells, whereas both LDH-A and LDH-B subunits were present in LNCaP cells. DCA was shown to significantly modify the metabolite ratios in highly metastatic LNCaP-LN3 cells, but not in poorly metastatic LNCaP cells. This effect was probably related to the absence of the LDH-B subunit in LNCaP-LN3 cells, and could have a bearing on cancer treatment with DCA and related compounds.
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Affiliation(s)
- Mithun Kailavasan
- Department of Cardiovascular Science, The Medical School, University of Sheffield, Sheffield, UK
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Shabalina IG, Vrbacký M, Pecinová A, Kalinovich AV, Drahota Z, Houštěk J, Mráček T, Cannon B, Nedergaard J. ROS production in brown adipose tissue mitochondria: the question of UCP1-dependence. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:2017-2030. [PMID: 24769119 DOI: 10.1016/j.bbabio.2014.04.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 04/08/2014] [Accepted: 04/14/2014] [Indexed: 02/05/2023]
Abstract
Whether active UCP1 can reduce ROS production in brown-fat mitochondria is presently not settled. The issue is of principal significance, as it can be seen as a proof- or disproof-of-principle concerning the ability of any protein to diminish ROS production through membrane depolarization. We therefore undertook a comprehensive investigation of the significance of UCP1 for ROS production, by comparing the ROS production in brown-fat mitochondria isolated from wildtype mice (that display membrane depolarization) or from UCP1(-/-) mice (with a high membrane potential). We tested the significance of UCP1 for glycerol-3-phosphate-supported ROS production by three methods (fluorescent dihydroethidium and the ESR probe PHH for superoxide, and fluorescent Amplex Red for hydrogen peroxide), and followed ROS production also with succinate, acyl-CoA or pyruvate as substrate. We studied the effects of the reverse electron flow inhibitor rotenone, the UCP1 activity inhibitor GDP, and the uncoupler FCCP. We also examined the effect of a physiologically induced increase in UCP1 amount. We noted GDP effects that were not UCP1-related. We conclude that only ROS production supported by exogenously added succinate was affected by the presence of active UCP1; ROS production supported by any other tested substrate (including endogenously generated succinate) was unaffected. This conclusion indicates that UCP1 is not involved in control of ROS production in brown-fat mitochondria. Extrapolation of these data to other tissues would imply that membrane depolarization may not necessarily decrease physiologically relevant ROS production. This article is a part of a Special Issue entitled: 18th European Bioenergetics Conference (Biochim. Biophys. Acta, Volume 1837, Issue 7, July 2014).
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Affiliation(s)
- Irina G Shabalina
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Marek Vrbacký
- Department of Bioenergetics, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ 142 20 Prague, Czech Republic
| | - Alena Pecinová
- Department of Bioenergetics, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ 142 20 Prague, Czech Republic
| | - Anastasia V Kalinovich
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Zdeněk Drahota
- Department of Bioenergetics, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ 142 20 Prague, Czech Republic
| | - Josef Houštěk
- Department of Bioenergetics, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ 142 20 Prague, Czech Republic
| | - Tomáš Mráček
- Department of Bioenergetics, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ 142 20 Prague, Czech Republic
| | - Barbara Cannon
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden.
| | - Jan Nedergaard
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
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Effect of white tea (Camellia sinensis (L.)) extract in the glycolytic profile of Sertoli cell. Eur J Nutr 2013; 53:1383-91. [PMID: 24363139 DOI: 10.1007/s00394-013-0640-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 12/06/2013] [Indexed: 10/25/2022]
Abstract
PURPOSE Many health benefits have been attributed to tea (Camellia sinensis (L.)), and tea infusions are used as dietary agent and included in food supplements. Herein, we report the effect of a white tea (WTEA) extract in Sertoli cell (SC) metabolism. The SC is responsible for the nutritional support of the developing germ cells. METHODS An aqueous WTEA extract was prepared and analyzed by (1)H-NMR. Rat SCs were cultured with or without the WTEA extract. mRNA and protein levels of glucose transporters (GLUT1 and GLUT3), phosphofructokinase, lactate dehydrogenase (LDH) and monocarboxylate transporter 4 were determined by qPCR and western blot. LDH activity was assessed and metabolite production/consumption determined by (1)H-NMR. RESULTS WTEA-exposed SCs presented decreased protein and mRNA levels of GLUT1 and decreased glucose uptake. However, intracellular LDH activity was increased and SC lactate production was stimulated by the presence of the WTEA extract. Interestingly, alanine production was also found to be stimulated in WTEA extract-exposed SCs. CONCLUSION WTEA extract altered the glycolytic profile of cultured SCs, stimulating lactate production. Since lactate is used as metabolic substrate and has an anti-apoptotic effect in the developing germ cells, the supplementation with WTEA extract may be advantageous to improve male reproductive health.
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Rato L, Duarte AI, Tomás GD, Santos MS, Moreira PI, Socorro S, Cavaco JE, Alves MG, Oliveira PF. Pre-diabetes alters testicular PGC1-α/SIRT3 axis modulating mitochondrial bioenergetics and oxidative stress. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:335-44. [PMID: 24361842 DOI: 10.1016/j.bbabio.2013.12.008] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 12/10/2013] [Accepted: 12/12/2013] [Indexed: 11/19/2022]
Abstract
Pre-diabetes, a risk factor for type 2 diabetes development, leads to metabolic changes at testicular level. Peroxisome proliferator-activated receptor γ coactivator 1 α (PGC-1α) and Sirtuin 3 (Sirt3) are pivotal in mitochondrial function. We hypothesized that pre-diabetes disrupts testicular PGC-1α/Sirt3 axis, compromising testicular mitochondrial function. Using a high-energy-diet induced pre-diabetic rat model, we evaluated testicular levels of PGC-1α and its downstream targets, nuclear respiratory factors 1 (NRF-1) and 2 (NRF-2), mitochondrial transcription factor A (TFAM) and Sirt3. We also assessed mitochondrial DNA (mtDNA) content, mitochondrial function, energy levels and oxidative stress parameters. Protein levels were quantified by Western Blot, mtDNA content was determined by qPCR. Mitochondrial complex activity and oxidative stress parameters were spectrophotometrically evaluated. Adenine nucleotide levels, adenosine and its metabolites (inosine and hypoxanthine) were determined by reverse-phase HPLC. Pre-diabetic rats showed increased blood glucose levels and impaired glucose tolerance. Both testicular PGC-1α and Sirt3 levels were decreased. NRF-1, NRF-2 and TFAM were not altered. Testicular mtDNA content was decreased. Mitochondrial complex I activity was increased, whereas mitochondrial complex III activity was decreased. Adenylate energy charge was decreased in pre-diabetic rats, as were ATP and ADP levels. Conversely, AMP levels were increased, evidencing a decreased ATP/AMP ratio. Concerning to oxidative stress pre-diabetes decreased testicular antioxidant capacity and increased lipid and protein oxidation. In sum, pre-diabetes compromises testicular mitochondrial function by repressing PGC-1α/Sirt3 axis and mtDNA copy number, declining respiratory capacity and increasing oxidative stress. This study gives new insights into overall testicular bioenergetics at this prodromal stage of disease.
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Affiliation(s)
- Luís Rato
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal; CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Ana I Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; Institute for Interdisciplinary Research (IIIUC), University of Coimbra, 3030-789 Coimbra, Portugal
| | - Gonçalo D Tomás
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal
| | - Maria S Santos
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; Life Sciences Department, Faculty of Sciences and Technology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Paula I Moreira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; Laboratory of Physiology, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Sílvia Socorro
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal
| | - José E Cavaco
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal
| | - Marco G Alves
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal
| | - Pedro F Oliveira
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal.
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Josan S, Park JM, Hurd R, Yen YF, Pfefferbaum A, Spielman D, Mayer D. In vivo investigation of cardiac metabolism in the rat using MRS of hyperpolarized [1-13C] and [2-13C]pyruvate. NMR IN BIOMEDICINE 2013; 26:1680-7. [PMID: 23904148 PMCID: PMC3838505 DOI: 10.1002/nbm.3003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 04/30/2013] [Accepted: 06/23/2013] [Indexed: 05/23/2023]
Abstract
Hyperpolarized (13)C MRS allows the in vivo assessment of pyruvate dehydrogenase complex (PDC) flux, which converts pyruvate to acetyl-coenzyme A (acetyl-CoA). [1-(13)C]pyruvate has been used to measure changes in cardiac PDC flux, with demonstrated increase in (13)C-bicarbonate production after dichloroacetate (DCA) administration. With [1-(13)C]pyruvate, the (13)C label is released as (13 CO2 /(13)C-bicarbonate, and, hence, does not allow us to follow the fate of acetyl-CoA. Pyruvate labeled in the C2 position has been used to track the (13)C label into the TCA (tricarboxylic acid) cycle and measure [5-(13)C]glutamate as well as study changes in [1-(13)C]acetylcarnitine with DCA and dobutamine. This work investigates changes in the metabolic fate of acetyl-CoA in response to metabolic interventions of DCA-induced increased PDC flux in the fed and fasted state, and increased cardiac workload with dobutamine in vivo in rat heart at two different pyruvate doses. DCA led to a modest increase in the (13)C labeling of [5-(13)C]glutamate, and a considerable increase in [1-(13)C]acetylcarnitine and [1,3-(13)C]acetoacetate peaks. Dobutamine resulted in an increased labeling of [2-(13)C]lactate, [2-(13)C]alanine and [5-(13)C]glutamate. The change in glutamate with dobutamine was observed using a high pyruvate dose but not with a low dose. The relative changes in the different metabolic products provide information about the relationship between PDC-mediated oxidation of pyruvate and its subsequent incorporation into the TCA cycle compared with other metabolic pathways. Using a high dose of pyruvate may provide an improved ability to observe changes in glutamate.
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Affiliation(s)
- Sonal Josan
- SRI International, Neuroscience Program, 333 Ravenswood Ave., Menlo Park, CA 94025
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
| | - Jae Mo Park
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
- Stanford University, Department of Electrical Engineering, Stanford, CA 94305
| | - Ralph Hurd
- GE Healthcare Applied Sciences Laboratory, 333 Ravenswood Ave., Menlo Park, CA 94025
| | - Yi-Fen Yen
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
| | - Adolf Pfefferbaum
- SRI International, Neuroscience Program, 333 Ravenswood Ave., Menlo Park, CA 94025
- Stanford University, Department of Psychiatry and Behavioral Sciences, 401 Quarry Rd., Stanford, CA 94305
| | - Daniel Spielman
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
- Stanford University, Department of Electrical Engineering, Stanford, CA 94305
| | - Dirk Mayer
- SRI International, Neuroscience Program, 333 Ravenswood Ave., Menlo Park, CA 94025
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
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Rato L, Alves MG, Dias TR, Lopes G, Cavaco JE, Socorro S, Oliveira PF. High-energy diets may induce a pre-diabetic state altering testicular glycolytic metabolic profile and male reproductive parameters. Andrology 2013; 1:495-504. [PMID: 23495257 DOI: 10.1111/j.2047-2927.2013.00071.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 12/26/2012] [Accepted: 01/14/2013] [Indexed: 12/30/2022]
Abstract
Diabetes mellitus is a metabolic disorder that may arise from diet habits and is growing to epidemic proportions. Young male diabetic patients present high infertility/subfertility prevalence resulting from impaired reproductive function and poor semen quality. We aimed to evaluate the effects of a high-energy diet (HED) on glucose tolerance/insulin levels and correlate the observed effects on male reproductive function with overall testicular metabolism. After 1 month, HED fed rats showed increased glycaemic levels, impaired glucose tolerance and hypoinsulinaemia. Moreover, an imbalance of intratesticular and serum testosterone levels was observed, whereas those of 17β-estradiol were not altered. High-energy diet also affected the reproductive parameters, with HED rats exhibiting a significant increase in abnormal sperm morphology. Glycolytic metabolism was favoured in testicles of HED rats with an increased expression of both glucose transporters 1 (GLUT1) and 3 (GLUT3) and the enzyme phosphofrutokinase 1. Moreover, lactate production and the expression of metabolism-associated genes and proteins involved in lactate production and transport were also enhanced by HED. Alanine testicular content was decreased and thus intratesticular lactate/alanine ratio in HED rats was increased, suggesting increased oxidative stress. Other energetic substrates such as acetate and creatine were not altered in testis from HED rats, but intratesticular glycine content was increased in those animals. Taken together, these results suggest that HED induces a pre-diabetic state that may impair reproductive function by modulating overall testicular metabolism. This is the first report on testicular metabolic features and mechanisms related with the onset of a pre-diabetic state.
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Affiliation(s)
- L Rato
- Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior CICS-UBI, Covilhã 6201-506, Portugal
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Vaz CV, Alves MG, Marques R, Moreira PI, Oliveira PF, Maia CJ, Socorro S. Androgen-responsive and nonresponsive prostate cancer cells present a distinct glycolytic metabolism profile. Int J Biochem Cell Biol 2012; 44:2077-84. [DOI: 10.1016/j.biocel.2012.08.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 08/02/2012] [Accepted: 08/09/2012] [Indexed: 12/30/2022]
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Metabolic modulation induced by oestradiol and DHT in immature rat Sertoli cells cultured in vitro. Biosci Rep 2012; 32:61-9. [PMID: 21671886 DOI: 10.1042/bsr20110030] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Sertoli cells actively metabolize glucose that is converted into lactate, which is used by developing germ cells for their energy metabolism. Androgens and oestrogens have general metabolic roles that reach far beyond reproductive processes. Hence, the main purpose of this study was to examine the effect of sex hormones on metabolite secretion/consumption in primary cultures of rat Sertoli cells. Sertoli cell-enriched cultures were maintained in a defined medium for 50 h. Glucose and pyruvate consumption, and lactate and alanine secretion were determined, by 1H-NMR (proton NMR) spectra analysis, in the presence or absence of 100 nM E2 (17β-oestradiol) or 100 nM 5α-DHT (dihydrotestosterone). Cells cultured in the absence (control) or presence of E2 consumed the same amount of glucose (29±2 pmol/cell) at similar rates during the 50 h. After 25 h of treatment with DHT, glucose consumption and glucose consumption rate significantly increased. Control and E2-treated cells secreted similar amounts of lactate during the 50 h, while the amount of lactate secreted by DHT-treated cells was significantly lower. Such a decrease was concomitant with a significant decrease in LDH A [LDH (lactate dehydrogenase) chain A] and MCT4 [MCT (monocarboxylate transporter) isoform 4] mRNA levels after 50 h treatment in hormonally treated groups, being more pronounced in DHT-treated groups. Finally, alanine production was significantly increased in E2-treated cells after 25 h treatment, which indicated a lower redox/higher oxidative state for the cells in those conditions. Together, these results support the existence of a relation between sex hormones action and energy metabolism, providing an important assessment of androgens and oestrogens as metabolic modulators in rat Sertoli cells.
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Mitochondrial ('mild') uncoupling and ROS production: physiologically relevant or not? Biochem Soc Trans 2012; 39:1305-9. [PMID: 21936806 DOI: 10.1042/bst0391305] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During the last decade, the possibility that 'mild' uncoupling could be protective against oxidative damage by diminishing ROS (reactive oxygen species) production has attracted much interest. In the present paper, we briefly examine the evidence for this possibility. It is only ROS production from succinate under reverse electron-flow conditions that is sensitive to membrane potential fluctuations, and so only this type of ROS production could be affected; however, the conditions under which succinate-supported ROS production is observed include succinate concentrations that are supraphysiological. Any decrease in membrane potential, even 'mild uncoupling', must necessarily lead to large increases in respiration, i.e. it must be markedly thermogenic. Mitochondria within cells are normally ATP-producing and thus already have a diminished membrane potential, and treatment of cells, organs or animals with small amounts of artificial uncoupler does not seem to have beneficial effects that are explainable via reduced ROS production. Although it has been suggested that members of the uncoupling protein family (UCP1, UCP2 and UCP3) may mediate a mild uncoupling, present evidence does not unequivocally support such an effect, e.g. the absence of the truly uncoupling protein UCP1 is not associated with increased oxidative damage. Thus present evidence does not support mild uncoupling as a physiologically relevant alleviator of oxidative damage.
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Schroeder MA, Atherton HJ, Dodd MS, Lee P, Cochlin LE, Radda GK, Clarke K, Tyler DJ. The cycling of acetyl-coenzyme A through acetylcarnitine buffers cardiac substrate supply: a hyperpolarized 13C magnetic resonance study. Circ Cardiovasc Imaging 2012; 5:201-9. [PMID: 22238215 DOI: 10.1161/circimaging.111.969451] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Carnitine acetyltransferase catalyzes the reversible conversion of acetyl-coenzyme A (CoA) into acetylcarnitine. The aim of this study was to use the metabolic tracer hyperpolarized [2-(13)C]pyruvate with magnetic resonance spectroscopy to determine whether carnitine acetyltransferase facilitates carbohydrate oxidation in the heart. METHODS AND RESULTS Ex vivo, following hyperpolarized [2-(13)C]pyruvate infusion, the [1-(13)C]acetylcarnitine resonance was saturated with a radiofrequency pulse, and the effect of this saturation on [1-(13)C]citrate and [5-(13)C]glutamate was observed. In vivo, [2-(13)C]pyruvate was infused into 3 groups of fed male Wistar rats: (1) controls, (2) rats in which dichloroacetate enhanced pyruvate dehydrogenase flux, and (3) rats in which dobutamine elevated cardiac workload. In the perfused heart, [1-(13)C]acetylcarnitine saturation reduced the [1-(13)C]citrate and [5-(13)C]glutamate resonances by 63% and 51%, respectively, indicating a rapid exchange between pyruvate-derived acetyl-CoA and the acetylcarnitine pool. In vivo, dichloroacetate increased the rate of [1-(13)C]acetylcarnitine production by 35% and increased the overall acetylcarnitine pool size by 33%. Dobutamine decreased the rate of [1-(13)C]acetylcarnitine production by 37% and decreased the acetylcarnitine pool size by 40%. CONCLUSIONS Hyperpolarized (13)C magnetic resonance spectroscopy has revealed that acetylcarnitine provides a route of disposal for excess acetyl-CoA and a means to replenish acetyl-CoA when cardiac workload is increased. Cycling of acetyl-CoA through acetylcarnitine appears key to matching instantaneous acetyl-CoA supply with metabolic demand, thereby helping to balance myocardial substrate supply and contractile function.
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Affiliation(s)
- Marie A Schroeder
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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Lopes G, Alves M, Carvalho R, Luvoni G, Rocha A. DNA fragmentation in canine oocytes after in vitro maturation in TCM-199 medium supplemented with different proteins. Theriogenology 2011; 76:1304-12. [DOI: 10.1016/j.theriogenology.2011.05.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 05/26/2011] [Accepted: 05/29/2011] [Indexed: 11/16/2022]
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Oliveira PF, Alves MG, Rato L, Silva J, Sá R, Barros A, Sousa M, Carvalho RA, Cavaco JE, Socorro S. Influence of 5α-dihydrotestosterone and 17β-estradiol on human Sertoli cells metabolism. ACTA ACUST UNITED AC 2011; 34:e612-20. [PMID: 21812787 DOI: 10.1111/j.1365-2605.2011.01205.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Sertoli cells metabolize glucose, converting it to lactate that is used by developing germ cells for their energy metabolism. Androgens and oestrogens have metabolic roles that reach far beyond reproductive processes. So, the main purpose of this study was to examine the effect of sex steroid hormones on metabolite secretion/consumption in human Sertoli cells. Human Sertoli cell-enriched primary cultures were maintained in a defined medium for 50 h and glucose, pyruvate, lactate and alanine variations were determined using (1) H-NMR spectra analysis, in the absence or presence of 100 nm 17β-estradiol (E(2) ) or 100 nm 5α-dihydrotestosterone (DHT). The mRNA expression levels of glucose transporters, lactate dehydrogenase and monocarboxylate transporters were also determined using semi-quantitative RT-PCR. Cells cultured in the absence (control) or presence of E(2) consumed the same amounts of glucose at similar rates during the 50 h. During the first 15 h of treatment with DHT, glucose consumption and glucose consumption rate were significantly higher. Nevertheless, DHT-treated cells secreted a significantly lower amount of lactate than control and E(2) -treated cells. Such a decrease was concomitant with a significant decrease in lactate dehydrogenase A mRNA levels after 50 h treatment in DHT-treated groups. Finally, alanine production was significantly increased in E(2) -treated cells after 25 h treatment, which indicated a lower redox/higher oxidative state for the cells on those conditions. These results support the existence of a relationship between sex steroid hormones action and energy metabolism, providing the first assessment of androgens and oestrogens as metabolic modulators of human Sertoli cells.
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Affiliation(s)
- P F Oliveira
- CICS - UBI - Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal.
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Nielsen TT, Støttrup NB, Løfgren B, Bøtker HE. Metabolic fingerprint of ischaemic cardioprotection: importance of the malate-aspartate shuttle. Cardiovasc Res 2011; 91:382-91. [PMID: 21349875 DOI: 10.1093/cvr/cvr051] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The convergence of cardioprotective intracellular signalling pathways to modulate mitochondrial function as an end-target of cytoprotective stimuli is well described. However, our understanding of whether the complementary changes in mitochondrial energy metabolism are secondary responses or inherent mechanisms of ischaemic cardioprotection remains incomplete. In the heart, the malate-aspartate shuttle (MAS) constitutes the primary metabolic pathway for transfer of reducing equivalents from the cytosol into the mitochondria for oxidation. The flux of MAS is tightly linked to the flux of the tricarboxylic acid cycle and the electron transport chain, partly by the amino acid l-glutamate. In addition, emerging evidence suggests the MAS is an important regulator of cytosolic and mitochondrial calcium homeostasis. In the isolated rat heart, inhibition of MAS during ischaemia and early reperfusion by the aminotransferase inhibitor aminooxyacetate induces infarct limitation, improves haemodynamic responses, and modulates glucose metabolism, analogous to effects observed in classical ischaemic preconditioning. On the basis of these findings, the mechanisms through which MAS preserves mitochondrial function and cell survival are reviewed. We conclude that the available evidence is supportive of a down-regulation of mitochondrial respiration during lethal ischaemia with a gradual 'wake-up' during reperfusion as a pivotal feature of ischaemic cardioprotection. Finally, comments on modulating myocardial energy metabolism by the cardioprotective amino acids glutamate and glutamine are given.
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Affiliation(s)
- Torsten Toftegaard Nielsen
- Department of Cardiology, Skejby Hospital, Aarhus University Hospital, Brendstrupgaardsvej 100, Aarhus N, Denmark.
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Binsl TW, Alders DJ, Heringa J, Groeneveld AJ, van Beek JH. Computational quantification of metabolic fluxes from a single isotope snapshot: application to an animal biopsy. Bioinformatics 2010; 26:653-60. [DOI: 10.1093/bioinformatics/btq018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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O'Donnell JM, Pound K, Xu X, Lewandowski ED. SERCA1 expression enhances the metabolic efficiency of improved contractility in post-ischemic heart. J Mol Cell Cardiol 2009; 47:614-21. [PMID: 19744494 DOI: 10.1016/j.yjmcc.2009.08.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 08/12/2009] [Accepted: 08/27/2009] [Indexed: 11/27/2022]
Abstract
Myocardial stunning is characterized by a metabolic uncoupling from function as mitochondrial tricarboxylic acid (TCA) cycle and oxygen consumption remain normal despite reduced contractility. Overexpression of the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA1) in hearts has recently been reported to reduce dysfunction at reperfusion. In this study we determine whether the metabolic coupling to function improves with SERCA treatment. PBS (control) or adenovirus carrying the cDNA for SERCA1 was delivered via coronary perfusion in vivo to Sprague-Dawley rat hearts. Three days following gene transfer, isolated hearts were perfused with 0.4 mM [2,4,6,8,10,12,14,16-13C8] palmitate and 5 mM glucose, and subjected to 15-min ischemia followed by 40-min reperfusion. Consistent with myocardial stunning, rate pressure product (RPP) and left ventricular developed pressure (LVDP) were depressed 30-40% (p<0.05) in the PBS group. With SERCA1 overexpression, dP/dt was 20% greater than controls (p<0.05), and LVDP and RPP recovered to pre-ischemic values. From dynamic 13C NMR, TCA cycle flux at reperfusion was similar to pre-ischemic values for both groups. Therefore, the efficiency of coupling between cardiac work and TCA cycle flux was restored with SERCA1 treatment. Oxidative efficiency was also enhanced with SERCA1 as cytosolic NADH transport into the mitochondria was significantly greater compared to the PBS group. In addition, the phosphocreatine to ATP ratio (PCr/ATP) was not compromised with SERCA1 expression, despite enhanced function, and depressed fatty acid oxidation at 40-min reperfusion in the PBS group was not reversed with SERCA1. These data demonstrate that metabolic coupling and NADH transport are significantly improved with SERCA1 treatment.
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Affiliation(s)
- J Michael O'Donnell
- Program in Integrative Cardiac Metabolism, Cardiovascular Research Center, Department of Physiology & Biophysics, College of Medicine, University of Illinois at Chicago, 835 South Wolcott Avenue (M/C 901), Chicago, IL 60612, USA.
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48
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Coggan AR, Kisrieva-Ware Z, Dence CS, Eisenbeis P, Gropler RJ, Herrero P. Measurement of myocardial fatty acid esterification using [1-11C]palmitate and PET: comparison with direct measurements of myocardial triglyceride synthesis. J Nucl Cardiol 2009; 16:562-70. [PMID: 19479313 PMCID: PMC2841400 DOI: 10.1007/s12350-009-9102-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 04/03/2009] [Accepted: 05/08/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND The purpose of the present study was to assess the accuracy of rates of myocardial fatty acid esterification (MFAE) obtained using positron emission tomography (PET). METHODS AND RESULTS Sixteen dogs were studied after an overnight fast (FAST), during a euglycemic hyperinsulinemic clamp (CLAMP), or during infusion of intralipid (IL) or IL plus dobutamine (IL/DOB). MFAE was quantified using [1-(11)C]palmitate and PET and compared to the rate of triglyceride (TG) synthesis measured using [1-(13)C]palmitate and tissue sampling. Plasma free fatty acid (FFA) concentration varied approximately 20-fold across groups, with this variation in FFA availability accompanied by a approximately 20-fold range in TG synthesis. MFAE varied approximately 12-fold across groups, and was significantly correlated with TG synthesis (R = 0.80, P < .001). MFAE, however, was 3- to 4-fold higher than TG synthesis in FAST, CLAMP, and IL, but only approximately 50% higher when cardiac work was increased in IL/DOB, suggesting that MFAE reflects, in part, the incorporation of label into amino acids via TCA cycle exchange reactions. CONCLUSIONS Changes in MFAE parallel changes in TG synthesis, at least in the basal state. Although the data need to be interpreted cautiously, such measurements should be useful for quantifying acute changes in FFA storage by the heart in various pathophysiological states.
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Affiliation(s)
- Andrew R Coggan
- Division of Radiological Sciences, Cardiovascular Imaging Laboratory, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 South Kingshighway Boulevard, St. Louis, MO 63110, USA.
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Bak LK, Walls AB, Schousboe A, Ring A, Sonnewald U, Waagepetersen HS. Neuronal glucose but not lactate utilization is positively correlated with NMDA-induced neurotransmission and fluctuations in cytosolic Ca2+ levels. J Neurochem 2009; 109 Suppl 1:87-93. [PMID: 19393013 DOI: 10.1111/j.1471-4159.2009.05943.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although the brain utilizes glucose for energy production, individual brain cells may to some extent utilize substrates derived from glucose. Thus, it has been suggested that neurons consume extracellular lactate during synaptic activity. However, the precise role of lactate for fueling neuronal activity is still poorly understood. Recently, we demonstrated that glucose metabolism is up-regulated in cultured glutamatergic neurons during neurotransmission whereas that of lactate is not. Here, we show that utilization of glucose but not lactate correlates with NMDA-induced neurotransmitter glutamate release in cultured cerebellar neurons from mice. Pulses of NMDA at 30, 100, and 300 microM, leading to a progressive increase in both cytosolic [Ca2+] and release of glutamate, increased uptake and metabolism of glucose but not that of lactate as evidenced by mass spectrometric measurement of 13C incorporation into intracellular glutamate. In this manuscript, a cascade of events for the preferential neuronal utilization of glucose during neurotransmission is suggested and discussed in relation to our current understanding of neuronal energy metabolism.
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Affiliation(s)
- Lasse K Bak
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark.
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50
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Contreras L, Satrústegui J. Calcium signaling in brain mitochondria: interplay of malate aspartate NADH shuttle and calcium uniporter/mitochondrial dehydrogenase pathways. J Biol Chem 2009; 284:7091-9. [PMID: 19129175 DOI: 10.1074/jbc.m808066200] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca2+ signaling in mitochondria has been mainly attributed to Ca2+ entry to the matrix through the Ca2+ uniporter and activation of mitochondrial matrix dehydrogenases. However, mitochondria can also sense increases in cytosolic Ca2+ through a mechanism that involves the aspartate-glutamate carriers, extramitochondrial Ca2+ activation of the NADH malate-aspartate shuttle (MAS). Both pathways are linked through the shared substrate alpha-ketoglutarate (alphaKG). Here we have studied the interplay between the two pathways under conditions of Ca2+ activation. We show that alphaKG becomes limiting when Ca2+ enters in brain or heart mitochondria, but not liver mitochondria, resulting in a drop in alphaKG efflux through the oxoglutarate carrier and in a drop in MAS activity. Inhibition of alphaKG efflux and MAS activity by matrix Ca2+ in brain mitochondria was fully reversible upon Ca2+ efflux. Because of their differences in cytosolic calcium concentration requirements, the MAS and Ca2+ uniporter-mitochondrial dehydrogenase pathways are probably sequentially activated during a Ca2+ transient, and the inhibition of MAS at the center of the transient may provide an explanation for part of the increase in lactate observed in the stimulated brain in vivo.
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Affiliation(s)
- Laura Contreras
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-CSIC and CIBER de Enfermedades Raras, 28049 Madrid, Spain
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