1
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Rushin A, McLeod MA, Ragavan M, Merritt ME. Observing exocrine pancreas metabolism using a novel pancreas perfusion technique in combination with hyperpolarized [1- 13 C]pyruvate. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2023; 61:748-758. [PMID: 37482899 PMCID: PMC10800648 DOI: 10.1002/mrc.5382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 06/28/2023] [Accepted: 07/06/2023] [Indexed: 07/25/2023]
Abstract
In a clinical setting, ex vivo perfusions are routinely used to maintain and assess organ viability prior to transplants. Organ perfusions are also a model system to examine metabolic flux while retaining the local physiological structure, with significant success using hyperpolarized (HP) 13 C NMR in this context. We use a novel exocrine pancreas perfusion technique via the common bile duct to assess acinar cell metabolism with HP [1-13 C]pyruvate. The exocrine component of the pancreas produces digestive enzymes through the ductal system and is often neglected in research on the pancreas. Real-time production of [1-13 C]lactate, [1-13 C]alanine, [1-13 C]malate, [4-13 C]malate, [1-13 C]aspartate, and H13 CO3 - was detected. The appearance of these resonances indicates flux through both pyruvate dehydrogenase and pyruvate carboxylase. We studied excised pancreata from C57BL/6J mice and NOD.Rag1-/- .AI4α/β mice, a commonly used model of Type 1 Diabetes (T1D). Pancreata from the T1D mice displayed increased lactate to alanine ratio without changes in oxygen consumption, signifying increased cytosolic NADH levels. The mass isotopologue analysis of the extracted pancreas tissue using gas chromatography-mass spectrometry revealed confirmatory 13 C enrichment in multiple TCA cycle metabolites that are products of pyruvate carboxylation. The methodology presented here has the potential to provide insight into mechanisms underlying several pancreatic diseases, such as diabetes, pancreatitis, and pancreatic cancer.
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Affiliation(s)
- Anna Rushin
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Marc A. McLeod
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Mukundan Ragavan
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
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2
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Ferro F, Spelat R, Valente C, Contessotto P. Understanding How Heart Metabolic Derangement Shows Differential Stage Specificity for Heart Failure with Preserved and Reduced Ejection Fraction. Biomolecules 2022; 12:biom12070969. [PMID: 35883525 PMCID: PMC9312956 DOI: 10.3390/biom12070969] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 06/30/2022] [Accepted: 07/06/2022] [Indexed: 12/12/2022] Open
Abstract
Heart failure (HF) is a clinical condition defined by structural and functional abnormalities in the heart that gradually result in reduced cardiac output (HFrEF) and/or increased cardiac pressures at rest and under stress (HFpEF). The presence of asymptomatic individuals hampers HF identification, resulting in delays in recognizing patients until heart dysfunction is manifested, thus increasing the chance of poor prognosis. Given the recent advances in metabolomics, in this review we dissect the main alterations occurring in the metabolic pathways behind the decrease in cardiac function caused by HF. Indeed, relevant preclinical and clinical research has been conducted on the metabolite connections and differences between HFpEF and HFrEF. Despite these promising results, it is crucial to note that, in addition to identifying single markers and reliable threshold levels within the healthy population, the introduction of composite panels would strongly help in the identification of those individuals with an increased HF risk. That said, additional research in the field is required to overcome the current drawbacks and shed light on the pathophysiological changes that lead to HF. Finally, greater collaborative data sharing, as well as standardization of procedures and approaches, would enhance this research field to fulfil its potential.
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Affiliation(s)
- Federico Ferro
- Department of Medical, Surgery and Health Sciences, University of Trieste, 34125 Trieste, Italy
- Correspondence:
| | - Renza Spelat
- Neurobiology Sector, International School for Advanced Studies (SISSA), 34136 Trieste, Italy;
| | - Camilla Valente
- Department of Molecular Medicine, University of Padova, 35122 Padova, Italy; (C.V.); (P.C.)
| | - Paolo Contessotto
- Department of Molecular Medicine, University of Padova, 35122 Padova, Italy; (C.V.); (P.C.)
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3
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Cilenti L, Mahar R, Di Gregorio J, Ambivero CT, Merritt ME, Zervos AS. Regulation of Metabolism by Mitochondrial MUL1 E3 Ubiquitin Ligase. Front Cell Dev Biol 2022; 10:904728. [PMID: 35846359 PMCID: PMC9277447 DOI: 10.3389/fcell.2022.904728] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 05/03/2022] [Indexed: 11/13/2022] Open
Abstract
MUL1 is a multifunctional E3 ubiquitin ligase that is involved in various pathophysiological processes including apoptosis, mitophagy, mitochondrial dynamics, and innate immune response. We uncovered a new function for MUL1 in the regulation of mitochondrial metabolism. We characterized the metabolic phenotype of MUL1(-/-) cells using metabolomic, lipidomic, gene expression profiling, metabolic flux, and mitochondrial respiration analyses. In addition, the mechanism by which MUL1 regulates metabolism was investigated, and the transcription factor HIF-1α, as well as the serine/threonine kinase Akt2, were identified as the mediators of the MUL1 function. MUL1 ligase, through K48-specific polyubiquitination, regulates both Akt2 and HIF-1α protein level, and the absence of MUL1 leads to the accumulation and activation of both substrates. We used specific chemical inhibitors and activators of HIF-1α and Akt2 proteins, as well as Akt2(-/-) cells, to investigate the individual contribution of HIF-1α and Akt2 proteins to the MUL1-specific phenotype. This study describes a new function of MUL1 in the regulation of mitochondrial metabolism and reveals how its downregulation/inactivation can affect mitochondrial respiration and cause a shift to a new metabolic and lipidomic state.
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Affiliation(s)
- Lucia Cilenti
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States
| | - Jacopo Di Gregorio
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Camilla T. Ambivero
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States
| | - Antonis S. Zervos
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
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4
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Hasenour CM, Rahim M, Young JD. In Vivo Estimates of Liver Metabolic Flux Assessed by 13C-Propionate and 13C-Lactate Are Impacted by Tracer Recycling and Equilibrium Assumptions. Cell Rep 2021; 32:107986. [PMID: 32755580 PMCID: PMC7451222 DOI: 10.1016/j.celrep.2020.107986] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 06/01/2020] [Accepted: 07/13/2020] [Indexed: 01/08/2023] Open
Abstract
Isotope-based assessment of metabolic flux is achieved through a judicious balance of measurements and assumptions. Recent publications debate the validity of key assumptions used to model stable isotope labeling of liver metabolism in vivo. Here, we examine the controversy surrounding estimates of liver citric acid cycle and gluconeogenesis fluxes using a flexible modeling platform that enables rigorous testing of standard assumptions. Fasted C57BL/6J mice are infused with [13C3]lactate or [13C3]propionate isotopes, and hepatic fluxes are regressed using models with gradually increasing complexity and relaxed assumptions. We confirm that liver pyruvate cycling fluxes are incongruent between different 13C tracers in models with conventional assumptions. When models are expanded to include more labeling measurements and fewer constraining assumptions, however, liver pyruvate cycling is significant, and inconsistencies in hepatic flux estimates using [13C3]lactate and [13C3]propionate isotopes emanate, in part, from peripheral tracer recycling and incomplete isotope equilibration within the citric acid cycle.
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Affiliation(s)
- Clinton M Hasenour
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Mohsin Rahim
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37235, USA.
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5
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Shaul D, Azar A, Sapir G, Uppala S, Nardi-Schreiber A, Gamliel A, Sosna J, Gomori JM, Katz-Brull R. Correlation between lactate dehydrogenase/pyruvate dehydrogenase activities ratio and tissue pH in the perfused mouse heart: A potential noninvasive indicator of cardiac pH provided by hyperpolarized magnetic resonance. NMR IN BIOMEDICINE 2021; 34:e4444. [PMID: 33258527 DOI: 10.1002/nbm.4444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 10/05/2020] [Accepted: 10/24/2020] [Indexed: 06/12/2023]
Abstract
Cardiovascular diseases account for more than 30% of all deaths worldwide and many could be ameliorated with early diagnosis. Current cardiac imaging modalities can assess blood flow, heart anatomy and mechanical function. However, for early diagnosis and improved treatment, further functional biomarkers are needed. One such functional biomarker could be the myocardium pH. Although tissue pH is already determinable via MR techniques, and has been since the early 1990s, it remains elusive to use practically. The objective of this study was to explore the possibility to evaluate cardiac pH noninvasively, using in-cell enzymatic rates of hyperpolarized [1-13 C]pyruvate metabolism (ie, moles of product produced per unit time) determined directly in real time using magnetic resonance spectroscopy in a perfused mouse heart model. As a gold standard for tissue pH we used 31 P spectroscopy and the chemical shift of the inorganic phosphate (Pi) signal. The nonhomogenous pH distribution of the perfused heart was analyzed using a multi-parametric analysis of this signal, thus taking into account the heterogeneous nature of this characteristic. As opposed to the signal ratio of hyperpolarized [13 C]bicarbonate to [13 CO2 ], which has shown correlation to pH in other studies, we investigated here the ratio of two intracellular enzymatic rates: lactate dehydrogenase (LDH) and pyruvate dehydrogenase (PDH), by way of determining the production rates of [1-13 C]lactate and [13 C]bicarbonate, respectively. The enzyme activities determined here are intracellular, while the pH determined using the Pi signal may contain an extracellular component, which could not be ruled out. Nevertheless, we report a strong correlation between the tissue pH and the LDH/PDH activities ratio. This work may pave the way for using the LDH/PDH activities ratio as an indicator of cardiac intracellular pH in vivo, in an MRI examination.
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Affiliation(s)
- David Shaul
- Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel
| | - Assad Azar
- Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel
| | - Gal Sapir
- Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel
| | - Sivaranjan Uppala
- Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel
| | - Atara Nardi-Schreiber
- Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel
| | - Ayelet Gamliel
- Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel
| | - Jacob Sosna
- Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel
| | - J Moshe Gomori
- Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel
| | - Rachel Katz-Brull
- Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel
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6
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Brew DW, Black MC, Santos M, Rodgers J, Henderson WM. Metabolomic Investigations of the Temporal Effects of Exposure to Pharmaceuticals and Personal Care Products and Their Mixture in the Eastern Oyster (Crassostrea virginica). ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2020; 39:419-436. [PMID: 31661721 DOI: 10.1002/etc.4627] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/21/2019] [Accepted: 10/22/2019] [Indexed: 06/10/2023]
Abstract
The eastern oyster (Crassostrea virginica) supports a large aquaculture industry and is a keystone species along the Atlantic seaboard. Native oysters are routinely exposed to a complex mixture of contaminants that increasingly includes pharmaceuticals and personal care products (PPCPs). Unfortunately, the biological effects of chemical mixtures on oysters are poorly understood. Untargeted gas chromatography-mass spectrometry metabolomics was utilized to quantify the response of oysters exposed to fluoxetine, N,N-diethyl-meta-toluamide, 17α-ethynylestradiol, diphenhydramine, and their mixture. Oysters were exposed to 1 µg/L of each chemical or mixture for 10 d, followed by an 8-d depuration period. Adductor muscle (n = 14/treatment) was sampled at days 0, 1, 5, 10, and 18. Trajectory analysis illustrated that metabolic effects and class separation of the treatments varied at each time point and that, overall, the oysters were only able to partially recover from these exposures post-depuration. Altered metabolites were associated with cellular energetics (i.e., Krebs cycle intermediates), as well as amino acid metabolism and fatty acids. Exposure to these PPCPs also affected metabolic pathways associated with anaerobic metabolism, osmotic stress, and oxidative stress, in addition to the physiological effects of each chemical's postulated mechanism of action. Following depuration, fewer metabolites were altered, but none of the treatments returned them to their initial control values, indicating that metabolic disruptions were long-lasting. Interestingly, the mixture did not directly cluster with individual treatments in the scores plot from partial least squares discriminant analysis, and many of its affected metabolic pathways were not well predicted from the individual treatments. The present study highlights the utility of untargeted metabolomics in developing exposure biomarkers for compounds with different modes of action in bivalves. Environ Toxicol Chem 2020;39:419-436. © 2019 SETAC.
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Affiliation(s)
- David W Brew
- Department of Environmental Health Science, University of Georgia, Athens, Georgia, USA
| | - Marsha C Black
- Department of Environmental Health Science, University of Georgia, Athens, Georgia, USA
| | - Marina Santos
- Department of Environmental Health Science, University of Georgia, Athens, Georgia, USA
| | - Jackson Rodgers
- Department of Environmental Health Science, University of Georgia, Athens, Georgia, USA
| | - W Matthew Henderson
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Athens, Georgia
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7
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Steinhauser J, Wespi P, Kwiatkowski G, Kozerke S. Production of highly polarized [1- 13 C]acetate by rapid decarboxylation of [2- 13 C]pyruvate - application to hyperpolarized cardiac spectroscopy and imaging. Magn Reson Med 2019; 82:1140-1149. [PMID: 31045272 DOI: 10.1002/mrm.27782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/27/2019] [Accepted: 04/03/2019] [Indexed: 11/10/2022]
Abstract
PURPOSE The objective of the present work was to develop and implement an efficient approach to hyperpolarize [1-13 C]acetate and apply it to in vivo cardiac spectroscopy and imaging. METHODS Rapid hydrogen peroxide induced decarboxylation was used to convert hyperpolarized [2-13 C]pyruvate into highly polarized [1-13 C]acetate employing an additional step following rapid dissolution of [2-13 C]pyruvate in a home-built multi-sample dissolution dynamic nuclear polarization system. Phantom dissolution experiments were conducted to determine optimal parameters of the decarboxylation reaction, retaining polarization and T1 of [1-13 C]acetate. In vivo feasibility of detecting [1-13 C]acetate metabolism is demonstrated using slice-selective spectroscopy and multi-echo imaging of [1-13 C]acetate and [1-13 C]acetylcarnitine in the healthy rat heart. RESULTS The first in vivo signal was observed ~23 s after dissolution. At the corresponding time point in the phantom experiments, 97.9 ± 0.4% of [2-13 C]pyruvate were converted into [1-13 C]acetate by the decarboxylation reaction. T1 and polarization of [1-13 C]acetate was determined to be 29.7 ± 1.9% and a 47.7 ± 0.5 s. Polarization levels of [2-13 C]pyruvate and [1-13 C]acetate were not significantly different after transfer to the scanner. In vivo, [1-13 C]acetate and [1-13 C]acetylcarnitine could be detected using spectroscopy and imaging. CONCLUSION Decarboxylation of hyperpolarized [2-13 C]pyruvate enables the efficient production of highly polarized [1-13 C]acetate that is applicable to study short-chain fatty acid metabolism in the in vivo heart.
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Affiliation(s)
- Jonas Steinhauser
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Patrick Wespi
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Grzegorz Kwiatkowski
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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8
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Wu CY, Satapati S, Gui W, Wynn RM, Sharma G, Lou M, Qi X, Burgess SC, Malloy C, Khemtong C, Sherry AD, Chuang DT, Merritt ME. A novel inhibitor of pyruvate dehydrogenase kinase stimulates myocardial carbohydrate oxidation in diet-induced obesity. J Biol Chem 2018; 293:9604-9613. [PMID: 29739849 DOI: 10.1074/jbc.ra118.002838] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/23/2018] [Indexed: 11/06/2022] Open
Abstract
The pyruvate dehydrogenase complex (PDC) is a key control point of energy metabolism and is subject to regulation by multiple mechanisms, including posttranslational phosphorylation by pyruvate dehydrogenase kinase (PDK). Pharmacological modulation of PDC activity could provide a new treatment for diabetic cardiomyopathy, as dysregulated substrate selection is concomitant with decreased heart function. Dichloroacetate (DCA), a classic PDK inhibitor, has been used to treat diabetic cardiomyopathy, but the lack of specificity and side effects of DCA indicate a more specific inhibitor of PDK is needed. This study was designed to determine the effects of a novel and highly selective PDK inhibitor, 2((2,4-dihydroxyphenyl)sulfonyl) isoindoline-4,6-diol (designated PS10), on pyruvate oxidation in diet-induced obese (DIO) mouse hearts compared with DCA-treated hearts. Four groups of mice were studied: lean control, DIO, DIO + DCA, and DIO + PS10. Both DCA and PS10 improved glucose tolerance in the intact animal. Pyruvate metabolism was studied in perfused hearts supplied with physiological mixtures of long chain fatty acids, lactate, and pyruvate. Analysis was performed using conventional 1H and 13C isotopomer methods in combination with hyperpolarized [1-13C]pyruvate in the same hearts. PS10 and DCA both stimulated flux through PDC as measured by the appearance of hyperpolarized [13C]bicarbonate. DCA but not PS10 increased hyperpolarized [1-13C]lactate production. Total carbohydrate oxidation was reduced in DIO mouse hearts but increased by DCA and PS10, the latter doing so without increasing lactate production. The present results suggest that PS10 is a more suitable PDK inhibitor for treatment of diabetic cardiomyopathy.
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Affiliation(s)
- Cheng-Yang Wu
- From the Department of Biochemistry.,Advanced Imaging Research Center
| | | | | | - R Max Wynn
- From the Department of Biochemistry.,Department of Internal Medicine, and
| | | | - Mingliang Lou
- Chemistry Center, National Institute of Biological Science, Beijing 102206, China, and.,Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Xiangbing Qi
- Chemistry Center, National Institute of Biological Science, Beijing 102206, China, and.,Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China
| | | | - Craig Malloy
- Advanced Imaging Research Center.,Department of Internal Medicine, and.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Chalermchai Khemtong
- Advanced Imaging Research Center.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - A Dean Sherry
- Advanced Imaging Research Center.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390.,Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080
| | - David T Chuang
- From the Department of Biochemistry, .,Department of Internal Medicine, and
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610,
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9
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Silvers MA, Deja S, Singh N, Egnatchik RA, Sudderth J, Luo X, Beg MS, Burgess SC, DeBerardinis RJ, Boothman DA, Merritt ME. The NQO1 bioactivatable drug, β-lapachone, alters the redox state of NQO1+ pancreatic cancer cells, causing perturbation in central carbon metabolism. J Biol Chem 2017; 292:18203-18216. [PMID: 28916726 DOI: 10.1074/jbc.m117.813923] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 09/13/2017] [Indexed: 12/21/2022] Open
Abstract
Many cancer treatments, such as those for managing recalcitrant tumors like pancreatic ductal adenocarcinoma, cause off-target toxicities in normal, healthy tissue, highlighting the need for more tumor-selective chemotherapies. β-Lapachone is bioactivated by NAD(P)H:quinone oxidoreductase 1 (NQO1). This enzyme exhibits elevated expression in most solid cancers and therefore is a potential cancer-specific target. β-Lapachone's therapeutic efficacy partially stems from the drug's induction of a futile NQO1-mediated redox cycle that causes high levels of superoxide and then peroxide formation, which damages DNA and causes hyperactivation of poly(ADP-ribose) polymerase, resulting in extensive NAD+/ATP depletion. However, the effects of this drug on energy metabolism due to NAD+ depletion were never described. The futile redox cycle rapidly consumes O2, rendering standard assays of Krebs cycle turnover unusable. In this study, a multimodal analysis, including metabolic imaging using hyperpolarized pyruvate, points to reduced oxidative flux due to NAD+ depletion after β-lapachone treatment of NQO1+ human pancreatic cancer cells. NAD+-sensitive pathways, such as glycolysis, flux through lactate dehydrogenase, and the citric acid cycle (as inferred by flux through pyruvate dehydrogenase), were down-regulated by β-lapachone treatment. Changes in flux through these pathways should generate biomarkers useful for in vivo dose responses of β-lapachone treatment in humans, avoiding toxic side effects. Targeting the enzymes in these pathways for therapeutic treatment may have the potential to synergize with β-lapachone treatment, creating unique NQO1-selective combinatorial therapies for specific cancers. These findings warrant future studies of intermediary metabolism in patients treated with β-lapachone.
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Affiliation(s)
- Molly A Silvers
- From the Departments of Pharmacology and Radiation Oncology, Simmons Comprehensive Cancer Center
| | - Stanislaw Deja
- Advanced Imaging Research Center (AIRC), Division of Metabolic Mechanisms of Disease
| | - Naveen Singh
- From the Departments of Pharmacology and Radiation Oncology, Simmons Comprehensive Cancer Center
| | - Robert A Egnatchik
- the Children's Medical Center Research Institute, Simmons Comprehensive Cancer Center
| | - Jessica Sudderth
- the Children's Medical Center Research Institute, Simmons Comprehensive Cancer Center
| | - Xiuquan Luo
- From the Departments of Pharmacology and Radiation Oncology, Simmons Comprehensive Cancer Center
| | | | - Shawn C Burgess
- Advanced Imaging Research Center (AIRC), Division of Metabolic Mechanisms of Disease
| | - Ralph J DeBerardinis
- the Children's Medical Center Research Institute, Simmons Comprehensive Cancer Center
| | - David A Boothman
- From the Departments of Pharmacology and Radiation Oncology, Simmons Comprehensive Cancer Center,
| | - Matthew E Merritt
- the AIRC, University of Texas Southwestern Medical Center, Dallas, Texas 75390 and .,the Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610
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10
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Ragavan M, Kirpich A, Fu X, Burgess SC, McIntyre LM, Merritt ME. A comprehensive analysis of myocardial substrate preference emphasizes the need for a synchronized fluxomic/metabolomic research design. Am J Physiol Heart Circ Physiol 2017; 312:H1215-H1223. [PMID: 28411229 DOI: 10.1152/ajpheart.00016.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/07/2017] [Accepted: 04/07/2017] [Indexed: 12/16/2022]
Abstract
The heart oxidizes fatty acids, carbohydrates, and ketone bodies inside the tricarboxylic acid (TCA) cycle to generate the reducing equivalents needed for ATP production. Competition between these substrates makes it difficult to estimate the extent of pyruvate oxidation. Previously, hyperpolarized pyruvate detected propionate-mediated activation of carbohydrate oxidation, even in the presence of acetate. In this report, the optimal concentration of propionate for the activation of glucose oxidation was measured in mouse hearts perfused in Langendorff mode. This study was performed with a more physiologically relevant perfusate than the previous work. Increasing concentrations of propionate did not cause adverse effects on myocardial metabolism, as evidenced by unchanged O2 consumption, TCA cycle flux, and developed pressures. Propionate at 1 mM was sufficient to achieve significant increases in pyruvate dehydrogenase flux (3×), and anaplerosis (6×), as measured by isotopomer analysis. These results further demonstrate the potential of propionate as an aid for the correct estimation of total carbohydrate oxidative capacity in the heart. However, liquid chromotography/mass spectroscopy-based metabolomics detected large changes (~30-fold) in malate and fumarate pool sizes. This observation leads to a key observation regarding mass balance in the TCA cycle; flux through a portion of the cycle can be drastically elevated without changing the O2 consumption.
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Affiliation(s)
- Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida
| | - Alexander Kirpich
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, Florida.,University of Florida Informatics Insititute, Gainesville, Florida; and
| | - Xiaorong Fu
- AIRC Division of Metabolic Mechanisms of Diseases, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Shawn C Burgess
- AIRC Division of Metabolic Mechanisms of Diseases, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pharmocology, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Lauren M McIntyre
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, Florida.,University of Florida Informatics Insititute, Gainesville, Florida; and.,University of Florida Genetics Insititute, Gainesville, Florida
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida;
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11
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Perry RJ, Borders CB, Cline GW, Zhang XM, Alves TC, Petersen KF, Rothman DL, Kibbey RG, Shulman GI. Propionate Increases Hepatic Pyruvate Cycling and Anaplerosis and Alters Mitochondrial Metabolism. J Biol Chem 2016; 291:12161-70. [PMID: 27002151 PMCID: PMC4933266 DOI: 10.1074/jbc.m116.720631] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Indexed: 02/03/2023] Open
Abstract
In mammals, pyruvate kinase (PK) plays a key role in regulating the balance between glycolysis and gluconeogenesis; however, in vivo regulation of PK flux by gluconeogenic hormones and substrates is poorly understood. To this end, we developed a novel NMR-liquid chromatography/tandem-mass spectrometry (LC-MS/MS) method to directly assess pyruvate cycling relative to mitochondrial pyruvate metabolism (VPyr-Cyc/VMito) in vivo using [3-(13)C]lactate as a tracer. Using this approach, VPyr-Cyc/VMito was only 6% in overnight fasted rats. In contrast, when propionate was infused simultaneously at doses previously used as a tracer, it increased VPyr-Cyc/VMito by 20-30-fold, increased hepatic TCA metabolite concentrations 2-3-fold, and increased endogenous glucose production rates by 20-100%. The physiologic stimuli, glucagon and epinephrine, both increased hepatic glucose production, but only glucagon suppressed VPyr-Cyc/VMito These data show that under fasting conditions, when hepatic gluconeogenesis is stimulated, pyruvate recycling is relatively low in liver compared with VMito flux and that liver metabolism, in particular pyruvate cycling, is sensitive to propionate making it an unsuitable tracer to assess hepatic glycolytic, gluconeogenic, and mitochondrial metabolism in vivo.
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Affiliation(s)
| | | | | | | | | | - Kitt Falk Petersen
- From the Departments of Internal Medicine, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen DK 1017, Denmark
| | - Douglas L Rothman
- Radiology and Biomedical Imaging, and the Department of Biomedical Engineering, Yale University, New Haven, Connecticut 06519, and
| | - Richard G Kibbey
- From the Departments of Internal Medicine, Cellular and Molecular Physiology, and
| | - Gerald I Shulman
- From the Departments of Internal Medicine, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen DK 1017, Denmark Cellular and Molecular Physiology, and the Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06519,
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Bastiaansen JA, Cheng T, Lei H, Gruetter R, Comment A. Direct noninvasive estimation of myocardial tricarboxylic acid cycle flux in vivo using hyperpolarized 13C magnetic resonance. J Mol Cell Cardiol 2015; 87:129-37. [DOI: 10.1016/j.yjmcc.2015.08.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 07/27/2015] [Accepted: 08/12/2015] [Indexed: 11/28/2022]
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Hyperpolarized (13)C Magnetic Resonance and Its Use in Metabolic Assessment of Cultured Cells and Perfused Organs. Methods Enzymol 2015; 561:73-106. [PMID: 26358902 DOI: 10.1016/bs.mie.2015.04.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Diseased tissue is often characterized by abnormalities in intermediary metabolism. Observing these alterations in situ may lead to an improved understanding of pathological processes and novel ways to monitor these processes noninvasively in human patients. Although (13)C is a stable isotope safe for use in animal models of disease as well as human subjects, its utility as a metabolic tracer has largely been limited to ex vivo analyses employing analytical techniques like mass spectrometry or nuclear magnetic resonance spectroscopy. Neither of these techniques is suitable for noninvasive metabolic monitoring, and the low abundance and poor gyromagnetic ratio of conventional (13)C make it a poor nucleus for imaging. However, the recent advent of hyperpolarization methods, particularly dynamic nuclear polarization (DNP), makes it possible to enhance the spin polarization state of (13)C by many orders of magnitude, resulting in a temporary amplification of the signal sufficient for monitoring kinetics of enzyme-catalyzed reactions in living tissue through magnetic resonance spectroscopy or magnetic resonance imaging. Here, we review DNP techniques to monitor metabolism in cultured cells, perfused hearts, and perfused livers, focusing on our experiences with hyperpolarized [1-(13)C]pyruvate. We present detailed approaches to optimize the DNP procedure, streamline biological sample preparation, and maximize detection of specific metabolic activities. We also discuss practical aspects in the choice of metabolic substrates for hyperpolarization studies and outline some of the current technical and conceptual challenges in the field, including efforts to use hyperpolarization to quantify metabolic rates in vivo.
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Clendinen CS, Stupp GS, Ajredini R, Lee-McMullen B, Beecher C, Edison AS. An overview of methods using (13)C for improved compound identification in metabolomics and natural products. FRONTIERS IN PLANT SCIENCE 2015; 6:611. [PMID: 26379677 PMCID: PMC4548202 DOI: 10.3389/fpls.2015.00611] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 07/23/2015] [Indexed: 05/11/2023]
Abstract
Compound identification is a major bottleneck in metabolomics studies. In nuclear magnetic resonance (NMR) investigations, resonance overlap often hinders unambiguous database matching or de novo compound identification. In liquid chromatography-mass spectrometry (LC-MS), discriminating between biological signals and background artifacts and reliable determination of molecular formulae are not always straightforward. We have designed and implemented several NMR and LC-MS approaches that utilize (13)C, either enriched or at natural abundance, in metabolomics applications. For LC-MS applications, we describe a technique called isotopic ratio outlier analysis (IROA), which utilizes samples that are isotopically labeled with 5% (test) and 95% (control) (13)C. This labeling strategy leads to characteristic isotopic patterns that allow the differentiation of biological signals from artifacts and yield the exact number of carbons, significantly reducing possible molecular formulae. The relative abundance between the test and control samples for every IROA feature can be determined simply by integrating the peaks that arise from the 5 and 95% channels. For NMR applications, we describe two (13)C-based approaches. For samples at natural abundance, we have developed a workflow to obtain (13)C-(13)C and (13)C-(1)H statistical correlations using 1D (13)C and (1)H NMR spectra. For samples that can be isotopically labeled, we describe another NMR approach to obtain direct (13)C-(13)C spectroscopic correlations. These methods both provide extensive information about the carbon framework of compounds in the mixture for either database matching or de novo compound identification. We also discuss strategies in which (13)C NMR can be used to identify unknown compounds from IROA experiments. By combining technologies with the same samples, we can identify important biomarkers and corresponding metabolites of interest.
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Affiliation(s)
- Chaevien S. Clendinen
- Southeast Center for Integrated Metabolomics, University of Florida, Gainesville, FL, USA
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | | | - Ramadan Ajredini
- Southeast Center for Integrated Metabolomics, University of Florida, Gainesville, FL, USA
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Brittany Lee-McMullen
- Southeast Center for Integrated Metabolomics, University of Florida, Gainesville, FL, USA
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Chris Beecher
- Southeast Center for Integrated Metabolomics, University of Florida, Gainesville, FL, USA
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
- IROA Technologies, Ann Arbor, MI, USA
| | - Arthur S. Edison
- Southeast Center for Integrated Metabolomics, University of Florida, Gainesville, FL, USA
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
- *Correspondence: Arthur S. Edison, Southeast Center for Integrated Metabolomics and Department of Biochemistry and Molecular Biology, University of Florida, 1600 Archer Road, Rm R3-226, Box 100245, Gainesville, FL 32610-0245, USA,
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