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Heather LC, Gopal K, Srnic N, Ussher JR. Redefining Diabetic Cardiomyopathy: Perturbations in Substrate Metabolism at the Heart of Its Pathology. Diabetes 2024; 73:659-670. [PMID: 38387045 PMCID: PMC11043056 DOI: 10.2337/dbi23-0019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 02/15/2024] [Indexed: 02/24/2024]
Abstract
Cardiovascular disease represents the leading cause of death in people with diabetes, most notably from macrovascular diseases such as myocardial infarction or heart failure. Diabetes also increases the risk of a specific form of cardiomyopathy, referred to as diabetic cardiomyopathy (DbCM), originally defined as ventricular dysfunction in the absence of underlying coronary artery disease and/or hypertension. Herein, we provide an overview on the key mediators of DbCM, with an emphasis on the role for perturbations in cardiac substrate metabolism. We discuss key mechanisms regulating metabolic dysfunction in DbCM, with additional focus on the role of metabolites as signaling molecules within the diabetic heart. Furthermore, we discuss the preclinical approaches to target these perturbations to alleviate DbCM. With several advancements in our understanding, we propose the following as a new definition for, or approach to classify, DbCM: "diastolic dysfunction in the presence of altered myocardial metabolism in a person with diabetes but absence of other known causes of cardiomyopathy and/or hypertension." However, we recognize that no definition can fully explain the complexity of why some individuals with DbCM exhibit diastolic dysfunction, whereas others develop systolic dysfunction. Due to DbCM sharing pathological features with heart failure with preserved ejection fraction (HFpEF), the latter of which is more prevalent in the population with diabetes, it is imperative to determine whether effective management of DbCM decreases HFpEF prevalence. ARTICLE HIGHLIGHTS
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Affiliation(s)
- Lisa C. Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Keshav Gopal
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
- Cardiovascular Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Nikola Srnic
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - John R. Ussher
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
- Cardiovascular Research Institute, University of Alberta, Edmonton, Alberta, Canada
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2
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Choksey A, Carter RD, Thackray BD, Ball V, Kennedy BWC, Ha LHT, Sharma E, Broxholme J, Castro-Guarda M, Murphy MP, Heather LC, Tyler DJ, Timm KN. AICAR confers prophylactic cardioprotection in doxorubicin-induced heart failure in rats. J Mol Cell Cardiol 2024:S0022-2828(24)00055-5. [PMID: 38643934 DOI: 10.1016/j.yjmcc.2024.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 04/12/2024] [Accepted: 04/18/2024] [Indexed: 04/23/2024]
Abstract
Doxorubicin (DOX) is a widely used chemotherapeutic agent that can cause serious cardiotoxic side effects, leading to heart failure (HF). Impaired mitochondrial function is thought to be key factor driving progression into HF. We have previously shown in a rat model of DOX-HF that heart failure with reduced ejection fraction correlates with mitochondrial loss and dysfunction. Adenosine monophosphate-dependent kinase (AMPK) is a cellular energy sensor, regulating mitochondrial biogenesis and energy metabolism, including fatty acid oxidation. We hypothesised that AMPK activation could restore mitochondrial function and therefore be a novel cardioprotective strategy for the prevention of DOX-HF. Consequently, we set out to assess whether 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR), an activator of AMPK, could prevent cardiac functional decline in this chronic intravenous rat model of DOX-HF. In line with our hypothesis, AICAR improved cardiac systolic function. AICAR furthermore improved cardiac mitochondrial fatty acid oxidation, independent of mitochondrial number, and in the absence of observable AMPK-activation. In addition, we found that AICAR prevented loss of myocardial mass. RNAseq analysis showed that this may be driven by normalisation of pathways associated with ribosome function and protein synthesis, which are impaired in DOX-treated rat hearts. AICAR furthermore prevented dyslipidemia and excessive body-weight loss in DOX-treated rats, which may contribute to preservation of myocardial mass. Though it is unclear whether AICAR exerted its cardioprotective effect through cardiac or extra-cardiac AMPK-activation or via an AMPK-independent effect, these results show promise for the use of AICAR as a cardioprotective agent in DOX-HF to both preserve cardiac function and mass.
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Affiliation(s)
- Anurag Choksey
- Department of Physiology Anatomy and Genetics, University of Oxford, UK
| | - Ryan D Carter
- Department of Physiology Anatomy and Genetics, University of Oxford, UK; Doctoral Training Centre, University of Oxford, Keble Road, Oxford, OX1 3NP, UK
| | | | - Vicky Ball
- Department of Physiology Anatomy and Genetics, University of Oxford, UK
| | - Brett W C Kennedy
- Department of Physiology Anatomy and Genetics, University of Oxford, UK; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, UK
| | | | - Eshita Sharma
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Dr, Headington, Oxford OX3 7BN, UK
| | - John Broxholme
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Dr, Headington, Oxford OX3 7BN, UK
| | | | | | - Lisa C Heather
- Department of Physiology Anatomy and Genetics, University of Oxford, UK
| | - Damian J Tyler
- Department of Physiology Anatomy and Genetics, University of Oxford, UK; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, UK
| | - Kerstin N Timm
- Department of Physiology Anatomy and Genetics, University of Oxford, UK; Department of Pharmacology, University of Oxford, UK.
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Glatz JFC, Heather LC, Luiken JJFP. CD36 as a gatekeeper of myocardial lipid metabolism and therapeutic target for metabolic disease. Physiol Rev 2024; 104:727-764. [PMID: 37882731 DOI: 10.1152/physrev.00011.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 10/02/2023] [Accepted: 10/22/2023] [Indexed: 10/27/2023] Open
Abstract
The multifunctional membrane glycoprotein CD36 is expressed in different types of cells and plays a key regulatory role in cellular lipid metabolism, especially in cardiac muscle. CD36 facilitates the cellular uptake of long-chain fatty acids, mediates lipid signaling, and regulates storage and oxidation of lipids in various tissues with active lipid metabolism. CD36 deficiency leads to marked impairments in peripheral lipid metabolism, which consequently impact on the cellular utilization of multiple different fuels because of the integrated nature of metabolism. The functional presence of CD36 at the plasma membrane is regulated by its reversible subcellular recycling from and to endosomes and is under the control of mechanical, hormonal, and nutritional factors. Aberrations in this dynamic role of CD36 are causally associated with various metabolic diseases, in particular insulin resistance, diabetic cardiomyopathy, and cardiac hypertrophy. Recent research in cardiac muscle has disclosed the endosomal proton pump vacuolar-type H+-ATPase (v-ATPase) as a key enzyme regulating subcellular CD36 recycling and being the site of interaction between various substrates to determine cellular substrate preference. In addition, evidence is accumulating that interventions targeting CD36 directly or modulating its subcellular recycling are effective for the treatment of metabolic diseases. In conclusion, subcellular CD36 localization is the major adaptive regulator of cellular uptake and metabolism of long-chain fatty acids and appears a suitable target for metabolic modulation therapy to mend failing hearts.
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Affiliation(s)
- Jan F C Glatz
- Department of Genetics & Cell Biology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Lisa C Heather
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Joost J F P Luiken
- Department of Genetics & Cell Biology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
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Machado ND, Heather LC, Harris AL, Higgins GS. Targeting mitochondrial oxidative phosphorylation: lessons, advantages, and opportunities. Br J Cancer 2023; 129:897-899. [PMID: 37563220 PMCID: PMC10491675 DOI: 10.1038/s41416-023-02394-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 07/25/2023] [Accepted: 08/01/2023] [Indexed: 08/12/2023] Open
Affiliation(s)
- Nicole D Machado
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Adrian L Harris
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom
| | - Geoff S Higgins
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, United Kingdom.
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Chu SM, Heather LC, Chuaiphichai S, Nicol T, Wright B, Miossec M, Bendall JK, Douglas G, Crabtree MJ, Channon KM. Cardiomyocyte tetrahydrobiopterin synthesis regulates fatty acid metabolism and susceptibility to ischaemia-reperfusion injury. Exp Physiol 2023; 108:874-890. [PMID: 37184360 PMCID: PMC10988529 DOI: 10.1113/ep090795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 03/07/2023] [Indexed: 05/16/2023]
Abstract
NEW FINDINGS What is the central question of this study? What are the physiological roles of cardiomyocyte-derived tetrahydrobiopterin (BH4) in cardiac metabolism and stress response? What is the main finding and its importance? Cardiomyocyte BH4 has a physiological role in cardiac metabolism. There was a shift of substrate preference from fatty acid to glucose in hearts with targeted deletion of BH4 synthesis. The changes in fatty-acid metabolic profile were associated with a protective effect in response to ischaemia-reperfusion (IR) injury, and reduced infarct size. Manipulating fatty acid metabolism via BH4 availability could play a therapeutic role in limiting IR injury. ABSTRACT Tetrahydrobiopterin (BH4) is an essential cofactor for nitric oxide (NO) synthases in which its production of NO is crucial for cardiac function. However, non-canonical roles of BH4 have been discovered recently and the cell-specific role of cardiomyocyte BH4 in cardiac function and metabolism remains to be elucidated. Therefore, we developed a novel mouse model of cardiomyocyte BH4 deficiency, by cardiomyocyte-specific deletion of Gch1, which encodes guanosine triphosphate cyclohydrolase I, a required enzyme for de novo BH4 synthesis. Cardiomyocyte (cm)Gch1 mRNA expression and BH4 levels from cmGch1 KO mice were significantly reduced compared to Gch1flox/flox (WT) littermates. Transcriptomic analyses and protein assays revealed downregulation of genes involved in fatty acid oxidation in cmGch1 KO hearts compared with WT, accompanied by increased triacylglycerol concentration within the myocardium. Deletion of cardiomyocyte BH4 did not alter basal cardiac function. However, the recovery of left ventricle function was improved in cmGch1 KO hearts when subjected to ex vivo ischaemia-reperfusion (IR) injury, with reduced infarct size compared to WT hearts. Metabolomic analyses of cardiac tissue after IR revealed that long-chain fatty acids were increased in cmGch1 KO hearts compared to WT, whereas at 5 min reperfusion (post-35 min ischaemia) fatty acid metabolite levels were higher in WT compared to cmGch1 KO hearts. These results indicate a new role for BH4 in cardiomyocyte fatty acid metabolism, such that reduction of cardiomyocyte BH4 confers a protective effect in response to cardiac IR injury. Manipulating cardiac metabolism via BH4 could play a therapeutic role in limiting IR injury.
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Affiliation(s)
- Sandy M. Chu
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Lisa C. Heather
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Surawee Chuaiphichai
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Thomas Nicol
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Benjamin Wright
- Oxford Genomics Centre, Wellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Matthieu Miossec
- Oxford Genomics Centre, Wellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Jennifer K. Bendall
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Gillian Douglas
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Mark J. Crabtree
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Keith M. Channon
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
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Dennis KMJH, Heather LC. Post-translational palmitoylation of metabolic proteins. Front Physiol 2023; 14:1122895. [PMID: 36909239 PMCID: PMC9998952 DOI: 10.3389/fphys.2023.1122895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 02/03/2023] [Indexed: 03/14/2023] Open
Abstract
Numerous cellular proteins are post-translationally modified by addition of a lipid group to their structure, which dynamically influences the proteome by increasing hydrophobicity of proteins often impacting protein conformation, localization, stability, and binding affinity. These lipid modifications include myristoylation and palmitoylation. Palmitoylation involves a 16-carbon saturated fatty acyl chain being covalently linked to a cysteine thiol through a thioester bond. Palmitoylation is unique within this group of modifications, as the addition of the palmitoyl group is reversible and enzyme driven, rapidly affecting protein targeting, stability and subcellular trafficking. The palmitoylation reaction is catalyzed by a large family of Asp-His-His-Cys (DHHCs) motif-containing palmitoyl acyltransferases, while the reverse reaction is catalyzed by acyl-protein thioesterases (APTs), that remove the acyl chain. Palmitoyl-CoA serves an important dual purpose as it is not only a key metabolite fueling energy metabolism, but is also a substrate for this PTM. In this review, we discuss protein palmitoylation in regulating substrate metabolism, focusing on membrane transport proteins and kinases that participate in substrate uptake into the cell. We then explore the palmitoylation of mitochondrial proteins and the palmitoylation regulatory enzymes, a less explored field for potential lipid metabolic regulation.
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Affiliation(s)
- Kaitlyn M J H Dennis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Heather LC, Hafstad AD, Halade GV, Harmancey R, Mellor KM, Mishra PK, Mulvihill EE, Nabben M, Nakamura M, Rider OJ, Ruiz M, Wende AR, Ussher JR. Guidelines on Models of Diabetic Heart Disease. Am J Physiol Heart Circ Physiol 2022; 323:H176-H200. [PMID: 35657616 PMCID: PMC9273269 DOI: 10.1152/ajpheart.00058.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Diabetes is a major risk factor for cardiovascular diseases, including diabetic cardiomyopathy, atherosclerosis, myocardial infarction, and heart failure. As cardiovascular disease represents the number one cause of death in people with diabetes, there has been a major emphasis on understanding the mechanisms by which diabetes promotes cardiovascular disease, and how antidiabetic therapies impact diabetic heart disease. With a wide array of models to study diabetes (both type 1 and type 2), the field has made major progress in answering these questions. However, each model has its own inherent limitations. Therefore, the purpose of this guidelines document is to provide the field with information on which aspects of cardiovascular disease in the human diabetic population are most accurately reproduced by the available models. This review aims to emphasize the advantages and disadvantages of each model, and to highlight the practical challenges and technical considerations involved. We will review the preclinical animal models of diabetes (based on their method of induction), appraise models of diabetes-related atherosclerosis and heart failure, and discuss in vitro models of diabetic heart disease. These guidelines will allow researchers to select the appropriate model of diabetic heart disease, depending on the specific research question being addressed.
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Affiliation(s)
- Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Anne D Hafstad
- Department of Medical Biology, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Ganesh V Halade
- Department of Medicine, The University of Alabama at Birmingham, Tampa, Florida, United States
| | - Romain Harmancey
- Department of Internal Medicine, Division of Cardiology, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, United States
| | | | - Paras K Mishra
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Erin E Mulvihill
- University of Ottawa Heart Institute, Ottawa, ON, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Miranda Nabben
- Departments of Genetics and Cell Biology, and Clinical Genetics, Maastricht University Medical Center, CARIM School of Cardiovascular Diseases, Maastricht, the Netherlands
| | - Michinari Nakamura
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Oliver J Rider
- University of Oxford Centre for Clinical Magnetic Resonance Research, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Matthieu Ruiz
- Montreal Heart Institute, Montreal, Quebec, Canada.,Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada
| | - Adam R Wende
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - John R Ussher
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada.,Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada.,Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
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Hazlehurst JM, Lim TR, Charlton C, Miller JJ, Gathercole LL, Cornfield T, Nikolaou N, Harris SE, Moolla A, Othonos N, Heather LC, Marjot T, Tyler DJ, Carr C, Hodson L, McKeating J, Tomlinson JW. Acute intermittent hypoxia drives hepatic de novo lipogenesis in humans and rodents. Metabol Open 2022; 14:100177. [PMID: 35313531 PMCID: PMC8933516 DOI: 10.1016/j.metop.2022.100177] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 03/12/2022] [Indexed: 02/09/2023] Open
Abstract
Background and aims Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver condition. It is tightly associated with an adverse metabolic phenotype (including obesity and type 2 diabetes) as well as with obstructive sleep apnoea (OSA) of which intermittent hypoxia is a critical component. Hepatic de novo lipogenesis (DNL) is a significant contributor to hepatic lipid content and the pathogenesis of NAFLD and has been proposed as a key pathway to target in the development of pharmacotherapies to treat NAFLD. Our aim is to use experimental models to investigate the impact of hypoxia on hepatic lipid metabolism independent of obesity and metabolic disease. Methods Human and rodent studies incorporating stable isotopes and hyperinsulinaemic euglycaemic clamp studies were performed to assess the regulation of DNL and broader metabolic phenotype by intermittent hypoxia. Cell-based studies, including pharmacological and genetic manipulation of hypoxia-inducible factors (HIF), were used to examine the underlying mechanisms. Results Hepatic DNL increased in response to acute intermittent hypoxia in humans, without alteration in glucose production or disposal. These observations were endorsed in a prolonged model of intermittent hypoxia in rodents using stable isotopic assessment of lipid metabolism. Changes in DNL were paralleled by increases in hepatic gene expression of acetyl CoA carboxylase 1 and fatty acid synthase. In human hepatoma cell lines, hypoxia increased both DNL and fatty acid uptake through HIF-1α and -2α dependent mechanisms. Conclusions These studies provide robust evidence linking intermittent hypoxia and the regulation of DNL in both acute and sustained in vivo models of intermittent hypoxia, providing an important mechanistic link between hypoxia and NAFLD.
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Affiliation(s)
- Jonathan M. Hazlehurst
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TT, UK
- Department of Diabetes and Endocrinology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Teegan Reina Lim
- Department of Gastro & Hepatology, Singapore General Hospital, Outram Road, 544894, Singapore
| | - Catriona Charlton
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Jack J. Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, University of Oxford, Oxford, OX1 3PT, UK
- Department of Physics, Clarendon Laboratory, Parks Road, OX1 3PUT, Oxford, UK
| | - Laura L. Gathercole
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Thomas Cornfield
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Nikolaos Nikolaou
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Shelley E. Harris
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Ahmad Moolla
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Nantia Othonos
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Lisa C. Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Thomas Marjot
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Damian J. Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, University of Oxford, Oxford, OX1 3PT, UK
| | - Carolyn Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, University of Oxford, Oxford, OX1 3PT, UK
| | - Leanne Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Jane McKeating
- Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Jeremy W. Tomlinson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
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Sousa Fialho MDL, Purnama U, Dennis KMJH, Montes Aparicio CN, Castro-Guarda M, Massourides E, Tyler DJ, Carr CA, Heather LC. Activation of HIF1α Rescues the Hypoxic Response and Reverses Metabolic Dysfunction in the Diabetic Heart. Diabetes 2021; 70:2518-2531. [PMID: 34526367 PMCID: PMC8564414 DOI: 10.2337/db21-0398] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 08/27/2021] [Indexed: 11/13/2022]
Abstract
Type 2 diabetes (T2D) impairs hypoxia-inducible factor (HIF)1α activation, a master transcription factor that drives cellular adaptation to hypoxia. Reduced activation of HIF1α contributes to the impaired post-ischemic remodeling observed following myocardial infarction in T2D. Molidustat is an HIF stabilizer currently undergoing clinical trials for the treatment of renal anemia associated with chronic kidney disease; however, it may provide a route to pharmacologically activate HIF1α in the T2D heart. In human cardiomyocytes, molidustat stabilized HIF1α and downstream HIF target genes, promoting anaerobic glucose metabolism. In hypoxia, insulin resistance blunted HIF1α activation and downstream signaling, but this was reversed by molidustat. In T2D rats, oral treatment with molidustat rescued the cardiac metabolic dysfunction caused by T2D, promoting glucose metabolism and mitochondrial function, while suppressing fatty acid oxidation and lipid accumulation. This resulted in beneficial effects on post-ischemic cardiac function, with the impaired contractile recovery in T2D heart reversed by molidustat treatment. In conclusion, pharmacological HIF1α stabilization can overcome the blunted hypoxic response induced by insulin resistance. In vivo this corrected the abnormal metabolic phenotype and impaired post-ischemic recovery of the diabetic heart. Therefore, molidustat may be an effective compound to further explore the clinical translatability of HIF1α activation in the diabetic heart.
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Affiliation(s)
| | - Ujang Purnama
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Kaitlyn M J H Dennis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | | | - Marcos Castro-Guarda
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Emmanuelle Massourides
- Centre d'Etude des Cellules Souches/I-Stem, INSERM UMR 861, AFM-Téléthon, Corbeil-Essonnes, France
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K.
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10
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Kerr M, Dennis KMJH, Carr CA, Fuller W, Berridge G, Rohling S, Aitken CL, Lopez C, Fischer R, Miller JJ, Clarke K, Tyler DJ, Heather LC. Diabetic mitochondria are resistant to palmitoyl CoA inhibition of respiration, which is detrimental during ischemia. FASEB J 2021; 35:e21765. [PMID: 34318967 PMCID: PMC8662312 DOI: 10.1096/fj.202100394r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/24/2021] [Accepted: 06/14/2021] [Indexed: 01/07/2023]
Abstract
The bioactive lipid intermediate palmitoyl CoA (PCoA) can inhibit mitochondrial ADP/ATP transport, though the physiological relevance of this regulation remains unclear. We questioned whether myocardial ischemia provides a pathological setting in which PCoA regulation of ADP/ATP transport would be beneficial, and secondly, whether the chronically elevated lipid content within the diabetic heart could make mitochondria less sensitive to the effects of PCoA. PCoA acutely decreased ADP‐stimulated state 3 respiration and increased the apparent Km for ADP twofold. The half maximal inhibitory concentration (IC50) of PCoA in control mitochondria was 22 µM. This inhibitory effect of PCoA on respiration was blunted in diabetic mitochondria, with no significant difference in the Km for ADP in the presence of PCoA, and an increase in the IC50 to 32 µM PCoA. The competitive inhibition by PCoA was localised to the phosphorylation apparatus, particularly the ADP/ATP carrier (AAC). During ischemia, the AAC imports ATP into the mitochondria, where it is hydrolysed by reversal of the ATP synthase, regenerating the membrane potential. Addition of PCoA dose‐dependently prevented this wasteful ATP hydrolysis for membrane repolarisation during ischemia, however, this beneficial effect was blunted in diabetic mitochondria. Finally, using 31P‐magnetic resonance spectroscopy we demonstrated that diabetic hearts lose ATP more rapidly during ischemia, with a threefold higher ATP decay rate compared with control hearts. In conclusion, PCoA plays a role in protecting mitochondrial energetics during ischemia, by preventing wasteful ATP hydrolysis. However, this beneficial effect is blunted in diabetes, contributing to the impaired energy metabolism seen during myocardial ischemia in the diabetic heart.
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Affiliation(s)
- M Kerr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - K M J H Dennis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - C A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - W Fuller
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - G Berridge
- Target Discovery Institute, University of Oxford, Oxford, UK
| | - S Rohling
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - C L Aitken
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - C Lopez
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - R Fischer
- Target Discovery Institute, University of Oxford, Oxford, UK
| | - J J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Department of Physics, University of Oxford, Oxford, UK.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - K Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - D J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - L C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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11
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Savic D, Ball V, Holzner L, Hauton D, Timm KN, Curtis MK, Heather LC, Tyler DJ. Hyperpolarized magnetic resonance shows that the anti-ischemic drug meldonium leads to increased flux through pyruvate dehydrogenase in vivo resulting in improved post-ischemic function in the diabetic heart. NMR Biomed 2021; 34:e4471. [PMID: 33458907 PMCID: PMC8609426 DOI: 10.1002/nbm.4471] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/20/2020] [Accepted: 12/20/2020] [Indexed: 05/07/2023]
Abstract
The diabetic heart has a decreased ability to metabolize glucose. The anti-ischemic drug meldonium may provide a route to counteract this by reducing l-carnitine levels, resulting in improved cardiac glucose utilization. Therefore, the aim of this study was to use the novel technique of hyperpolarized magnetic resonance to investigate the in vivo effects of treatment with meldonium on cardiac metabolism and function in control and diabetic rats. Thirty-six male Wistar rats were injected either with vehicle, or with streptozotocin (55 mg/kg) to induce a model of type 1 diabetes. Daily treatment with either saline or meldonium (100 mg/kg/day) was undertaken for three weeks. in vivo cardiac function and metabolism were assessed with CINE MRI and hyperpolarized magnetic resonance respectively. Isolated perfused hearts were challenged with low-flow ischemia/reperfusion to assess the impact of meldonium on post-ischemic recovery. Meldonium had no significant effect on blood glucose concentrations or on baseline cardiac function. However, hyperpolarized magnetic resonance revealed that meldonium treatment elevated pyruvate dehydrogenase flux by 3.1-fold and 1.2-fold in diabetic and control animals, respectively, suggesting an increase in cardiac glucose oxidation. Hyperpolarized magnetic resonance further demonstrated that meldonium reduced the normalized acetylcarnitine signal by 2.1-fold in both diabetic and control animals. The increase in pyruvate dehydrogenase flux in vivo was accompanied by an improvement in post-ischemic function ex vivo, as meldonium elevated the rate pressure product by 1.3-fold and 1.5-fold in the control and diabetic animals, respectively. In conclusion, meldonium improves in vivo pyruvate dehydrogenase flux in the diabetic heart, contributing to improved cardiac recovery after ischemia.
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Affiliation(s)
- Dragana Savic
- Cardiac Metabolism Research Group (CMRG), Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Vicky Ball
- Cardiac Metabolism Research Group (CMRG), Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Lorenz Holzner
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
| | - David Hauton
- Cardiac Metabolism Research Group (CMRG), Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
- Metabolomics Research Group, Department of ChemistryUniversity of OxfordOxfordUK
| | - Kerstin N. Timm
- Cardiac Metabolism Research Group (CMRG), Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - M. Kate Curtis
- Cardiac Metabolism Research Group (CMRG), Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Lisa C. Heather
- Cardiac Metabolism Research Group (CMRG), Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Damian J. Tyler
- Cardiac Metabolism Research Group (CMRG), Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
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12
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Savic D, Ball V, Curtis MK, Sousa Fialho MDL, Timm KN, Hauton D, West J, Griffin J, Heather LC, Tyler DJ. L-Carnitine Stimulates In Vivo Carbohydrate Metabolism in the Type 1 Diabetic Heart as Demonstrated by Hyperpolarized MRI. Metabolites 2021; 11:metabo11030191. [PMID: 33806953 PMCID: PMC8004902 DOI: 10.3390/metabo11030191] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/15/2021] [Accepted: 03/19/2021] [Indexed: 01/25/2023] Open
Abstract
The diabetic heart is energetically and metabolically abnormal, with increased fatty acid oxidation and decreased glucose oxidation. One factor contributing to the metabolic dysfunction in diabetes may be abnormal handling of acetyl and acyl groups by the mitochondria. L-carnitine is responsible for their transfer across the mitochondrial membrane, therefore, supplementation with L-carnitine may provide a route to improve the metabolic state of the diabetic heart. The primary aim of this study was to use hyperpolarized magnetic resonance imaging (MRI) to investigate the effects of L-carnitine supplementation on the in vivo metabolism of [1-13C]pyruvate in diabetes. Male Wistar rats were injected with either vehicle or streptozotocin (55 mg/kg) to induce type-1 diabetes. Three weeks of daily i.p. treatment with either saline or L-carnitine (3 g/kg/day) was subsequently undertaken. In vivo cardiac function and metabolism were assessed with CINE and hyperpolarized MRI, respectively. L-carnitine supplementation prevented the progression of hyperglycemia, which was observed in untreated streptozotocin injected animals and led to reductions in plasma triglyceride and ß-hydroxybutyrate concentrations. Hyperpolarized MRI revealed that L-carnitine treatment elevated pyruvate dehydrogenase flux by 3-fold in the diabetic animals, potentially through increased buffering of excess acetyl-CoA units in the mitochondria. Improved functional recovery following ischemia was also observed in the L-carnitine treated diabetic animals.
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Affiliation(s)
- Dragana Savic
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK; (V.B.); (M.K.C.); (M.d.L.S.F.); (K.N.T.); (D.H.); (L.C.H.); (D.J.T.)
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX1 3PT, UK
- Correspondence:
| | - Vicky Ball
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK; (V.B.); (M.K.C.); (M.d.L.S.F.); (K.N.T.); (D.H.); (L.C.H.); (D.J.T.)
| | - M. Kate Curtis
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK; (V.B.); (M.K.C.); (M.d.L.S.F.); (K.N.T.); (D.H.); (L.C.H.); (D.J.T.)
| | - Maria da Luz Sousa Fialho
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK; (V.B.); (M.K.C.); (M.d.L.S.F.); (K.N.T.); (D.H.); (L.C.H.); (D.J.T.)
| | - Kerstin N. Timm
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK; (V.B.); (M.K.C.); (M.d.L.S.F.); (K.N.T.); (D.H.); (L.C.H.); (D.J.T.)
- Department of Pharmacology, University of Oxford, Oxford OX1 3PT, UK
| | - David Hauton
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK; (V.B.); (M.K.C.); (M.d.L.S.F.); (K.N.T.); (D.H.); (L.C.H.); (D.J.T.)
- Metabolomics Research Group, Department of Chemistry, University of Oxford, Oxford OX1 3PT, UK
| | - James West
- Department of Medicine, University of Cambridge, Cambridge CB2 1TN, UK;
| | - Julian Griffin
- Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK;
| | - Lisa C. Heather
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK; (V.B.); (M.K.C.); (M.d.L.S.F.); (K.N.T.); (D.H.); (L.C.H.); (D.J.T.)
| | - Damian J. Tyler
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK; (V.B.); (M.K.C.); (M.d.L.S.F.); (K.N.T.); (D.H.); (L.C.H.); (D.J.T.)
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX1 3PT, UK
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13
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Wells MA, See Hoe LE, Heather LC, Molenaar P, Suen JY, Peart J, McGiffin D, Fraser JF. Peritransplant Cardiometabolic and Mitochondrial Function: The Missing Piece in Donor Heart Dysfunction and Graft Failure. Transplantation 2021; 105:496-508. [PMID: 33617201 DOI: 10.1097/tp.0000000000003368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Primary graft dysfunction is an important cause of morbidity and mortality after cardiac transplantation. Donor brain stem death (BSD) is a significant contributor to donor heart dysfunction and primary graft dysfunction. There remain substantial gaps in the mechanistic understanding of peritransplant cardiac dysfunction. One of these gaps is cardiac metabolism and metabolic function. The healthy heart is an "omnivore," capable of utilizing multiple sources of nutrients to fuel its enormous energetic demand. When this fails, metabolic inflexibility leads to myocardial dysfunction. Data have hinted at metabolic disturbance in the BSD donor and subsequent heart transplantation; however, there is limited evidence demonstrating specific metabolic or mitochondrial dysfunction. This review will examine the literature surrounding cardiometabolic and mitochondrial function in the BSD donor, organ preservation, and subsequent cardiac transplantation. A more comprehensive understanding of this subject may then help to identify important cardioprotective strategies to improve the number and quality of donor hearts.
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Affiliation(s)
- Matthew A Wells
- School of medical Science, Griffith University Gold Coast, Australia
- Critical Care Research Group, The Prince Charles Hospital, Chermside, Australia
| | - Louise E See Hoe
- Critical Care Research Group, The Prince Charles Hospital, Chermside, Australia
- Prince Charles Hospital Northside Clinical Unit, Faculty of Medicine, University of Queensland, St Lucia, Australia
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter Molenaar
- Faculty of Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane City, Australia
| | - Jacky Y Suen
- Critical Care Research Group, The Prince Charles Hospital, Chermside, Australia
- Prince Charles Hospital Northside Clinical Unit, Faculty of Medicine, University of Queensland, St Lucia, Australia
| | - Jason Peart
- School of medical Science, Griffith University Gold Coast, Australia
| | - David McGiffin
- Critical Care Research Group, The Prince Charles Hospital, Chermside, Australia
- Cardiothoracic Surgery and Transplantation, The Alfred Hospital, Melbourne, Australia
| | - John F Fraser
- School of medical Science, Griffith University Gold Coast, Australia
- Critical Care Research Group, The Prince Charles Hospital, Chermside, Australia
- Prince Charles Hospital Northside Clinical Unit, Faculty of Medicine, University of Queensland, St Lucia, Australia
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14
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Miller JJ, Valkovič L, Kerr M, Timm KN, Watson WD, Lau JYC, Tyler A, Rodgers C, Bottomley PA, Heather LC, Tyler DJ. Rapid, B 1 -insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux. Magn Reson Med 2021; 85:2978-2991. [PMID: 33538063 PMCID: PMC7986077 DOI: 10.1002/mrm.28647] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/28/2020] [Accepted: 11/24/2020] [Indexed: 12/16/2022]
Abstract
PURPOSE Phosphorus saturation-transfer experiments can quantify metabolic fluxes noninvasively. Typically, the forward flux through the creatine kinase reaction is investigated by observing the decrease in phosphocreatine (PCr) after saturation of γ-ATP. The quantification of total ATP utilization is currently underexplored, as it requires simultaneous saturation of inorganic phosphate ( P i ) and PCr. This is challenging, as currently available saturation pulses reduce the already-low γ-ATP signal present. METHODS Using a hybrid optimal-control and Shinnar-Le Roux method, a quasi-adiabatic RF pulse was designed for the dual saturation of PCr and P i to enable determination of total ATP utilization. The pulses were evaluated in Bloch equation simulations, compared with a conventional hard-cosine DANTE saturation sequence, before being applied to perfused rat hearts at 11.7 T. RESULTS The quasi-adiabatic pulse was insensitive to a >2.5-fold variation in B 1 , producing equivalent saturation with a 53% reduction in delivered pulse power and a 33-fold reduction in spillover at the minimum effective B 1 . This enabled the complete quantification of the synthesis and degradation fluxes for ATP in 30-45 minutes in the perfused rat heart. While the net synthesis flux (4.24 ± 0.8 mM/s, SEM) was not significantly different from degradation flux (6.88 ± 2 mM/s, P = .06) and both measures are consistent with prior work, nonlinear error analysis highlights uncertainties in the Pi -to-ATP measurement that may explain a trend suggesting a possible imbalance. CONCLUSIONS This work demonstrates a novel quasi-adiabatic dual-saturation RF pulse with significantly improved performance that can be used to measure ATP turnover in the heart in vivo.
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Affiliation(s)
- Jack J Miller
- Department of Physics, University of Oxford, Oxford, UK.,Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford, UK.,Health, Aarhus University, Aarhus, Denmark
| | - Ladislav Valkovič
- Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford, UK.,Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Matthew Kerr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Kerstin N Timm
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - William D Watson
- Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford, UK
| | - Justin Y C Lau
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford, UK
| | - Andrew Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford, UK
| | - Christopher Rodgers
- Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford, UK.,Wolfson Brain Imaging Centre, University of Cambridge, Oxford, UK
| | - Paul A Bottomley
- Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford, UK.,Division of MR Research, Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford, UK
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15
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Timm KN, Perera C, Ball V, Henry JA, Miller JJ, Kerr M, West JA, Sharma E, Broxholme J, Logan A, Savic D, Dodd MS, Griffin JL, Murphy MP, Heather LC, Tyler DJ. Early detection of doxorubicin-induced cardiotoxicity in rats by its cardiac metabolic signature assessed with hyperpolarized MRI. Commun Biol 2020; 3:692. [PMID: 33214680 PMCID: PMC7678845 DOI: 10.1038/s42003-020-01440-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 10/28/2020] [Indexed: 12/13/2022] Open
Abstract
Doxorubicin (DOX) is a widely used chemotherapeutic agent that can cause serious cardiotoxic side effects culminating in congestive heart failure (HF). There are currently no clinical imaging techniques or biomarkers available to detect DOX-cardiotoxicity before functional decline. Mitochondrial dysfunction is thought to be a key factor driving functional decline, though real-time metabolic fluxes have never been assessed in DOX-cardiotoxicity. Hyperpolarized magnetic resonance imaging (MRI) can assess real-time metabolic fluxes in vivo. Here we show that cardiac functional decline in a clinically relevant rat-model of DOX-HF is preceded by a change in oxidative mitochondrial carbohydrate metabolism, measured by hyperpolarized MRI. The decreased metabolic fluxes were predominantly due to mitochondrial loss and additional mitochondrial dysfunction, and not, as widely assumed hitherto, to oxidative stress. Since hyperpolarized MRI has been successfully translated into clinical trials this opens up the potential to test cancer patients receiving DOX for early signs of cardiotoxicity.
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Affiliation(s)
- Kerstin N Timm
- Department of Physiology Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK.
| | - Charith Perera
- Department of Physiology Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Vicky Ball
- Department of Physiology Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - John A Henry
- Department of Physiology Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Jack J Miller
- Department of Physiology Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Matthew Kerr
- Department of Physiology Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - James A West
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Eshita Sharma
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Dr, Headington, Oxford, OX3 7BN, UK
| | - John Broxholme
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Dr, Headington, Oxford, OX3 7BN, UK
| | - Angela Logan
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Dragana Savic
- Department of Physiology Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Michael S Dodd
- Department of Physiology Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Julian L Griffin
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Michael P Murphy
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Lisa C Heather
- Department of Physiology Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Damian J Tyler
- Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford, OX3 9DU, UK
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16
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Faulkner A, Tamiato A, Cathery W, Rampin A, Caravaggi CM, Jover E, Allen S, Mellor H, Hauton D, Heather LC, Spinetti G, Madeddu P. Dimethyl-2-oxoglutarate improves redox balance and mitochondrial function in muscle pericytes of individuals with diabetes mellitus. Diabetologia 2020; 63:2205-2217. [PMID: 32728894 PMCID: PMC7476972 DOI: 10.1007/s00125-020-05230-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 05/22/2020] [Indexed: 12/28/2022]
Abstract
AIMS/HYPOTHESIS Treatment of vascular complications of diabetes remains inadequate. We reported that muscle pericytes (MPs) from limb muscles of vascular patients with diabetes mellitus display elevated levels of oxidative stress causing a dysfunctional phenotype. Here, we investigated whether treatment with dimethyl-2-oxoglutarate (DM-2OG), a tricarboxylic acid cycle metabolite with antioxidant properties, can restore a healthy metabolic and functional phenotype. METHODS MPs were isolated from limb muscles of diabetes patients with vascular disease (D-MPs) and from non-diabetic control participants (ND-MPs). Metabolic status was assessed in untreated and DM-2OG-treated (1 mmol/l) cells using an extracellular flux analyser and anion-exchange chromatography-mass spectrometry (IC-MS/MS). Redox status was measured using commercial kits and IC-MS/MS, with antioxidant and metabolic enzyme expression assessed by quantitative RT-PCR and western blotting. Myogenic differentiation and proliferation and pericyte-endothelial interaction were assessed as functional readouts. RESULTS D-MPs showed mitochondrial dysfunction, suppressed glycolytic activity and reduced reactive oxygen species-buffering capacity, but no suppression of antioxidant systems when compared with ND-MP controls. DM-2OG supplementation improved redox balance and mitochondrial function, without affecting glycolysis or antioxidant systems. Nonetheless, this was not enough for treated D-MPs to regain the level of proliferation and myogenic differentiation of ND-MPs. Interestingly, DM-2OG exerted a positive effect on pericyte-endothelial cell interaction in the co-culture angiogenesis assay, independent of the diabetic status. CONCLUSIONS/INTERPRETATION These novel findings support the concept of using DM-2OG supplementation to improve pericyte redox balance and mitochondrial function, while concurrently allowing for enhanced pericyte-endothelial crosstalk. Such effects may help to prevent or slow down vasculopathy in skeletal muscles of people with diabetes. Graphical abstract.
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Affiliation(s)
- Ashton Faulkner
- Bristol Medical School, Translational Health Sciences, University of Bristol, Upper Maudlin Street, Bristol, BS2 8HW, UK.
- School of Biochemistry, University of Bristol, University Walk, Bristol, BS8 1TD, UK.
| | - Anita Tamiato
- Bristol Medical School, Translational Health Sciences, University of Bristol, Upper Maudlin Street, Bristol, BS2 8HW, UK
| | - William Cathery
- Bristol Medical School, Translational Health Sciences, University of Bristol, Upper Maudlin Street, Bristol, BS2 8HW, UK
| | | | | | - Eva Jover
- Bristol Medical School, Translational Health Sciences, University of Bristol, Upper Maudlin Street, Bristol, BS2 8HW, UK
| | - Steve Allen
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - Harry Mellor
- School of Biochemistry, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - David Hauton
- Department of Chemistry, University of Oxford, Oxford, UK
| | - Lisa C Heather
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, UK
| | | | - Paolo Madeddu
- Bristol Medical School, Translational Health Sciences, University of Bristol, Upper Maudlin Street, Bristol, BS2 8HW, UK.
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17
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Kerr M, Miller JJ, Thapa D, Stiewe S, Timm KN, Aparicio CNM, Scott I, Tyler DJ, Heather LC. Rescue of myocardial energetic dysfunction in diabetes through the correction of mitochondrial hyperacetylation by honokiol. JCI Insight 2020; 5:140326. [PMID: 32879143 PMCID: PMC7526448 DOI: 10.1172/jci.insight.140326] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 07/16/2020] [Indexed: 11/22/2022] Open
Abstract
Cardiac energetic dysfunction has been reported in patients with type 2 diabetes (T2D) and is an independent predictor of mortality. Identification of the mechanisms driving mitochondrial dysfunction, and therapeutic strategies to rescue these modifications, will improve myocardial energetics in T2D. We demonstrate using 31P-magnetic resonance spectroscopy (31P-MRS) that decreased cardiac ATP and phosphocreatine (PCr) concentrations occurred before contractile dysfunction or a reduction in PCr/ATP ratio in T2D. Real-time mitochondrial ATP synthesis rates and state 3 respiration rates were similarly depressed in T2D, implicating dysfunctional mitochondrial energy production. Driving this energetic dysfunction in T2D was an increase in mitochondrial protein acetylation, and increased ex vivo acetylation was shown to proportionally decrease mitochondrial respiration rates. Treating T2D rats in vivo with the mitochondrial deacetylase SIRT3 activator honokiol reversed the hyperacetylation of mitochondrial proteins and restored mitochondrial respiration rates to control levels. Using 13C-hyperpolarized MRS, respiration with different substrates, and enzyme assays, we localized this improvement to increased glutamate dehydrogenase activity. Finally, honokiol treatment increased ATP and PCr concentrations and increased total ATP synthesis flux in the T2D heart. In conclusion, hyperacetylation drives energetic dysfunction in T2D, and reversing acetylation with the SIRT3 activator honokiol rescued myocardial and mitochondrial energetics in T2D. Pharmacologically targeting mitochondrial acetylation provides a mechanism to rescue impaired myocardial energy generation in type 2 diabetes.
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Affiliation(s)
- Matthew Kerr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Jack J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom.,Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, United Kingdom.,Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Dharendra Thapa
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Sophie Stiewe
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Kerstin N Timm
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Iain Scott
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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18
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Mereweather LJ, Montes Aparicio CN, Heather LC. Positioning Metabolism as a Central Player in the Diabetic Heart. J Lipid Atheroscler 2020; 9:92-109. [PMID: 32821724 PMCID: PMC7379068 DOI: 10.12997/jla.2020.9.1.92] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/28/2019] [Accepted: 12/29/2019] [Indexed: 12/13/2022] Open
Abstract
In type 2 diabetes (T2D), the leading cause of death is cardiovascular complications. One mechanism contributing to cardiac pathogenesis is alterations in metabolism, with the diabetic heart exhibiting increased fatty acid oxidation and reduced glucose utilisation. The processes classically thought to underlie this metabolic shift include the Randle cycle and changes to gene expression. More recently, alternative mechanisms have been proposed, most notably, changes in post-translational modification of mitochondrial proteins in the heart. This increased understanding of how metabolism is altered in the diabetic heart has highlighted new therapeutic targets, with an aim to improve cardiac function in T2D. This review focuses on metabolism in the healthy heart and how this is modified in T2D, providing evidence for the mechanisms underlying this shift. There will be emphasis on the current treatments for the heart in diabetes, alongside efforts for metabocentric pharmacological therapies.
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Affiliation(s)
- Laura J Mereweather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | | | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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19
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Sirey TM, Roberts K, Haerty W, Bedoya-Reina O, Rogatti-Granados S, Tan JY, Li N, Heather LC, Carter RN, Cooper S, Finch AJ, Wills J, Morton NM, Marques AC, Ponting CP. Correction: The long non-coding RNA Cerox1 is a post transcriptional regulator of mitochondrial complex I catalytic activity. eLife 2019; 8:50980. [PMID: 31403403 PMCID: PMC6690732 DOI: 10.7554/elife.50980] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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20
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Le Page LM, Rider OJ, Lewis AJ, Noden V, Kerr M, Giles L, Ambrose LJ, Ball V, Mansor L, Heather LC, Tyler DJ. Assessing the effect of hypoxia on cardiac metabolism using hyperpolarized 13 C magnetic resonance spectroscopy. NMR Biomed 2019; 32:e4099. [PMID: 31090979 PMCID: PMC6619452 DOI: 10.1002/nbm.4099] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/14/2019] [Accepted: 03/06/2019] [Indexed: 05/03/2023]
Abstract
Hypoxia plays a role in many diseases and can have a wide range of effects on cardiac metabolism depending on the extent of the hypoxic insult. Noninvasive imaging methods could shed valuable light on the metabolic effects of hypoxia on the heart in vivo. Hyperpolarized carbon-13 magnetic resonance spectroscopy (HP 13 C MRS) in particular is an exciting technique for imaging metabolism that could provide such information. The aim of our work was, therefore, to establish whether hyperpolarized 13 C MRS can be used to assess the in vivo heart's metabolism of pyruvate in response to systemic acute and chronic hypoxic exposure. Groups of healthy male Wistar rats were exposed to either acute (30 minutes), 1 week or 3 weeks of hypoxia. In vivo MRS of hyperpolarized [1-13 C] pyruvate was carried out along with assessments of physiological parameters and ejection fraction. Hematocrit was elevated after 1 week and 3 weeks of hypoxia. 30 minutes of hypoxia resulted in a significant reduction in pyruvate dehydrogenase (PDH) flux, whereas 1 or 3 weeks of hypoxia resulted in a PDH flux that was not different to normoxic animals. Conversion of hyperpolarized [1-13 C] pyruvate into [1-13 C] lactate was elevated following acute hypoxia, suggestive of enhanced anaerobic glycolysis. Elevated HP pyruvate to lactate conversion was also seen at the one week timepoint, in concert with an increase in lactate dehydrogenase (LDH) expression. Following three weeks of hypoxic exposure, cardiac metabolism of pyruvate was comparable with that observed in normoxia. We have successfully visualized the effects of systemic hypoxia on cardiac metabolism of pyruvate using hyperpolarized 13 C MRS, with differences observed following 30 minutes and 1 week of hypoxia. This demonstrates the potential of in vivo hyperpolarized 13 C MRS data for assessing the cardiometabolic effects of hypoxia in disease.
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Affiliation(s)
- Lydia M. Le Page
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
- Department of Physical Therapy and Rehabilitation ScienceUniversity of CaliforniaSan FranciscoSan FranciscoUSA
- Department of Radiology and Biomedical ImagingUniversity of CaliforniaSan FranciscoSan FranciscoUSA
| | - Oliver J. Rider
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular MedicineUniversity of OxfordOxfordUK
| | - Andrew J. Lewis
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular MedicineUniversity of OxfordOxfordUK
| | - Victoria Noden
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Matthew Kerr
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Lucia Giles
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Lucy J.A. Ambrose
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Vicky Ball
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Latt Mansor
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Lisa C. Heather
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Damian J. Tyler
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular MedicineUniversity of OxfordOxfordUK
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21
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Sirey TM, Roberts K, Haerty W, Bedoya-Reina O, Rogatti-Granados S, Tan JY, Li N, Heather LC, Carter RN, Cooper S, Finch AJ, Wills J, Morton NM, Marques AC, Ponting CP. The long non-coding RNA Cerox1 is a post transcriptional regulator of mitochondrial complex I catalytic activity. eLife 2019; 8:45051. [PMID: 31045494 PMCID: PMC6542586 DOI: 10.7554/elife.45051] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 05/02/2019] [Indexed: 12/11/2022] Open
Abstract
To generate energy efficiently, the cell is uniquely challenged to co-ordinate the abundance of electron transport chain protein subunits expressed from both nuclear and mitochondrial genomes. How an effective stoichiometry of this many constituent subunits is co-ordinated post-transcriptionally remains poorly understood. Here we show that Cerox1, an unusually abundant cytoplasmic long noncoding RNA (lncRNA), modulates the levels of mitochondrial complex I subunit transcripts in a manner that requires binding to microRNA-488-3p. Increased abundance of Cerox1 cooperatively elevates complex I subunit protein abundance and enzymatic activity, decreases reactive oxygen species production, and protects against the complex I inhibitor rotenone. Cerox1 function is conserved across placental mammals: human and mouse orthologues effectively modulate complex I enzymatic activity in mouse and human cells, respectively. Cerox1 is the first lncRNA demonstrated, to our knowledge, to regulate mitochondrial oxidative phosphorylation and, with miR-488-3p, represent novel targets for the modulation of complex I activity. Animal cells generate over 90% of the energy they need within small structures called mitochondria. Converting food into energy requires many different proteins and cells control the relative amounts of the proteins in mitochondria to ensure this process is efficient. To make more of a given protein, the cell must copy the DNA of the gene that encodes it into another molecule known as a messenger RNA, before reading the instructions in the messenger RNA to build the protein. However, this is not the only way that a cell uses molecules of RNA. A second group of RNAs called long non-coding RNAs (or lncRNAs) can help regulate the production of proteins in complex ways, and each lncRNA can have an effect across multiple genes. Some lncRNAs, for example, stop a third group of RNAs – microRNAs – from blocking certain messenger RNAs from being read. Sirey et al. set out to answer whether a lncRNA might help to co-ordinate the production of the many proteins needed by mitochondria. In experiments with mouse cells grown in the laboratory, Sirey et al. identified a lncRNA called Cerox1 that can co-ordinate the levels of at least 12 mitochondrial proteins. A microRNA called miR-488-3p suppresses the production of many of these proteins. By binding to miR-488-3p, Cerox1 blocks the effects of the microRNA so more proteins are produced. Sirey et al. artificially altered the amount of Cerox1 in the cells and showed that more Cerox1 leads to higher mitochondria activity. Further experiments revealed that this same control system also exists in human cells. Mitochondria are vital to cell survival and changes that affect their efficiency can be fatal or highly debilitating. Reduced efficiency is also a hallmark of ageing and contributes to conditions including cardiovascular disease, diabetes and Parkinson’s disease. Understanding how mitochondria are regulated could unlock new treatment methods for these conditions, while a better understanding of the co-ordination of protein production offers other insights into some of the most fundamental biology.
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Affiliation(s)
- Tamara M Sirey
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom.,MRC Functional Genomics Unit, University of Oxford, Oxford, United Kingdom
| | - Kenny Roberts
- MRC Functional Genomics Unit, University of Oxford, Oxford, United Kingdom
| | - Wilfried Haerty
- MRC Functional Genomics Unit, University of Oxford, Oxford, United Kingdom
| | - Oscar Bedoya-Reina
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom.,MRC Functional Genomics Unit, University of Oxford, Oxford, United Kingdom
| | - Sebastian Rogatti-Granados
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom.,MRC Functional Genomics Unit, University of Oxford, Oxford, United Kingdom
| | - Jennifer Y Tan
- MRC Functional Genomics Unit, University of Oxford, Oxford, United Kingdom
| | - Nick Li
- MRC Functional Genomics Unit, University of Oxford, Oxford, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Roderick N Carter
- University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Sarah Cooper
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Andrew J Finch
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Jimi Wills
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Nicholas M Morton
- University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Chris P Ponting
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom.,MRC Functional Genomics Unit, University of Oxford, Oxford, United Kingdom
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Sousa Fialho MDL, Abd Jamil AH, Stannard GA, Heather LC. Hypoxia-inducible factor 1 signalling, metabolism and its therapeutic potential in cardiovascular disease. Biochim Biophys Acta Mol Basis Dis 2019; 1865:831-843. [DOI: 10.1016/j.bbadis.2018.09.024] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/24/2018] [Accepted: 09/18/2018] [Indexed: 12/20/2022]
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23
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Carr CA, Dodd MS, Heather LC. Bernard and Joan Marshall Awards at the autumn meeting of the British Society for Cardiovascular Research 2017. Heart 2018; 104:1383-1384. [PMID: 29925542 DOI: 10.1136/heartjnl-2018-313271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Michael S Dodd
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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24
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Mansor LS, Sousa Fialho MDL, Yea G, Coumans WA, West JA, Kerr M, Carr CA, Luiken JJFP, Glatz JFC, Evans RD, Griffin JL, Tyler DJ, Clarke K, Heather LC. Inhibition of sarcolemmal FAT/CD36 by sulfo-N-succinimidyl oleate rapidly corrects metabolism and restores function in the diabetic heart following hypoxia/reoxygenation. Cardiovasc Res 2018; 113:737-748. [PMID: 28419197 PMCID: PMC5437367 DOI: 10.1093/cvr/cvx045] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 03/23/2017] [Indexed: 11/14/2022] Open
Abstract
Aims The type 2 diabetic heart oxidizes more fat and less glucose, which can impair metabolic flexibility and function. Increased sarcolemmal fatty acid translocase (FAT/CD36) imports more fatty acid into the diabetic myocardium, feeding increased fatty acid oxidation and elevated lipid deposition. Unlike other metabolic modulators that target mitochondrial fatty acid oxidation, we proposed that pharmacologically inhibiting fatty acid uptake, as the primary step in the pathway, would provide an alternative mechanism to rebalance metabolism and prevent lipid accumulation following hypoxic stress. Methods and results Hearts from type 2 diabetic and control male Wistar rats were perfused in normoxia, hypoxia and reoxygenation, with the FAT/CD36 inhibitor sulfo-N-succinimidyl oleate (SSO) infused 4 min before hypoxia. SSO infusion into diabetic hearts decreased the fatty acid oxidation rate by 29% and myocardial triglyceride concentration by 48% compared with untreated diabetic hearts, restoring fatty acid metabolism to control levels following hypoxia-reoxygenation. SSO infusion increased the glycolytic rate by 46% in diabetic hearts during hypoxia, increased pyruvate dehydrogenase activity by 53% and decreased lactate efflux rate by 56% compared with untreated diabetic hearts during reoxygenation. In addition, SSO treatment of diabetic hearts increased intermediates within the second span of the Krebs cycle, namely fumarate, oxaloacetate, and the FAD total pool. The cardiac dysfunction in diabetic hearts following decreased oxygen availability was prevented by SSO-infusion prior to the hypoxic stress. Infusing SSO into diabetic hearts increased rate pressure product by 60% during hypoxia and by 32% following reoxygenation, restoring function to control levels. Conclusions Diabetic hearts have limited metabolic flexibility and cardiac dysfunction when stressed, which can be rapidly rectified by reducing fatty acid uptake with the FAT/CD36 inhibitor, SSO. This novel therapeutic approach not only reduces fat oxidation but also lipotoxicity, by targeting the primary step in the fatty acid metabolism pathway.
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Affiliation(s)
- Latt S Mansor
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Maria da Luz Sousa Fialho
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Georgina Yea
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Will A Coumans
- Department of Molecular Genetics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - James A West
- Department of Biochemistry, University of Cambridge, and MRC Human Nutrition Research, Cambridge, UK
| | - Matthew Kerr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Joost J F P Luiken
- Department of Molecular Genetics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Jan F C Glatz
- Department of Molecular Genetics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Rhys D Evans
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Julian L Griffin
- Department of Biochemistry, University of Cambridge, and MRC Human Nutrition Research, Cambridge, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
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25
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Le Page LM, Ball DR, Ball V, Dodd MS, Miller JJ, Heather LC, Tyler DJ. Simultaneous in vivo assessment of cardiac and hepatic metabolism in the diabetic rat using hyperpolarized MRS. NMR Biomed 2016; 29:1759-1767. [PMID: 27779334 PMCID: PMC5132204 DOI: 10.1002/nbm.3656] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 08/24/2016] [Accepted: 09/12/2016] [Indexed: 05/07/2023]
Abstract
Understanding and assessing diabetic metabolism is vital for monitoring disease progression and improving treatment of patients. In vivo assessments, using MRI and MRS, provide non-invasive and accurate measurements, and the development of hyperpolarized 13 C spectroscopy in particular has been demonstrated to provide valuable metabolic data in real time. Until now, studies have focussed on individual organs. However, diabetes is a systemic disease affecting multiple tissues in the body. Therefore, we have developed a technique to simultaneously measure metabolism in both the heart and liver during a single acquisition. A hyperpolarized 13 C MRS protocol was developed to allow acquisition of metabolic data from the heart and liver during a single scan. This protocol was subsequently used to assess metabolism in the heart and liver of seven control male Wistar rats and seven diabetic rats (diabetes was induced by three weeks of high-fat feeding and a 30 mg/kg injection of streptozotocin). Using our new acquisition, we observed decreased cardiac and hepatic pyruvate dehydrogenase flux in our diabetic rat model. These diabetic rats also had increased blood glucose levels, decreased insulin, and increased hepatic triglycerides. Decreased production of hepatic [1-13 C]alanine was observed in the diabetic group, but this change was not present in the hearts of the same diabetic animals. We have demonstrated the ability to measure cardiac and hepatic metabolism simultaneously, with sufficient sensitivity to detect metabolic alterations in both organs. Further, we have non-invasively observed the different reactions of the heart and liver to the metabolic challenge of diabetes.
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Affiliation(s)
- Lydia M. Le Page
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and GeneticsUniversity of OxfordOxfordUK
- Department of Radiology and Biomedical ImagingUniversity of CaliforniaSan FranciscoCAUSA
| | - Daniel R. Ball
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Vicky Ball
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Michael S. Dodd
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Jack J. Miller
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Lisa C. Heather
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Damian J. Tyler
- Cardiac Metabolism Research Group, Department of Physiology Anatomy and GeneticsUniversity of OxfordOxfordUK
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Lewis AJM, Miller JJJ, McCallum C, Rider OJ, Neubauer S, Heather LC, Tyler DJ. Assessment of Metformin-Induced Changes in Cardiac and Hepatic Redox State Using Hyperpolarized[1-13C]Pyruvate. Diabetes 2016; 65:3544-3551. [PMID: 27561726 DOI: 10.2337/db16-0804] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 08/19/2016] [Indexed: 11/13/2022]
Abstract
Metformin improves cardiovascular outcomes in type 2 diabetes, but its exact mechanisms of action remain controversial. We used hyperpolarized [1-13C]pyruvate magnetic resonance spectroscopy to determine the effects of metformin treatment on heart and liver pyruvate metabolism in rats in vivo. Both oral treatment for 4 weeks and a single intravenous metformin infusion significantly increased the cardiac [1-13C]lactate:[1-13C]pyruvate ratio but had no effect on the [1-13C]bicarbonate + 13CO2:[1-13C]pyruvate ratio, an index of pyruvate dehydrogenase flux. These changes were paralleled by a significant increase in the heart and liver cytosolic redox state, estimated from the [lactate]:[pyruvate] ratio but not the whole-cell [NAD+]/[NADH] ratio. Hyperpolarized MRI localized the increase in cardiac lactate to the left ventricular myocardium, implying a direct myocardial effect, though metformin had no effect on systolic or diastolic cardiac function. These findings demonstrate the ability of hyperpolarized pyruvate magnetic resonance spectroscopy to detect metformin-induced changes in cytosolic redox biology, suggest that metformin has a previously unrecognized effect on cardiac redox state, and help to refine the design of impending hyperpolarized magnetic resonance studies in humans.
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Affiliation(s)
- Andrew J M Lewis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
- Oxford Centre for Clinical Magnetic Resonance Research, Radcliffe Department of Medicine, University of Oxford, Oxford, U.K
| | - Jack J J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, U.K
| | - Chloe McCallum
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Oliver J Rider
- Oxford Centre for Clinical Magnetic Resonance Research, Radcliffe Department of Medicine, University of Oxford, Oxford, U.K
| | - Stefan Neubauer
- Oxford Centre for Clinical Magnetic Resonance Research, Radcliffe Department of Medicine, University of Oxford, Oxford, U.K
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K.
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27
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Lakhal-Littleton S, Wolna M, Chung YJ, Christian HC, Heather LC, Brescia M, Ball V, Diaz R, Santos A, Biggs D, Clarke K, Davies B, Robbins PA. An essential cell-autonomous role for hepcidin in cardiac iron homeostasis. eLife 2016; 5. [PMID: 27897970 PMCID: PMC5176354 DOI: 10.7554/elife.19804] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 11/24/2016] [Indexed: 12/16/2022] Open
Abstract
Hepcidin is the master regulator of systemic iron homeostasis. Derived primarily from the liver, it inhibits the iron exporter ferroportin in the gut and spleen, the sites of iron absorption and recycling respectively. Recently, we demonstrated that ferroportin is also found in cardiomyocytes, and that its cardiac-specific deletion leads to fatal cardiac iron overload. Hepcidin is also expressed in cardiomyocytes, where its function remains unknown. To define the function of cardiomyocyte hepcidin, we generated mice with cardiomyocyte-specific deletion of hepcidin, or knock-in of hepcidin-resistant ferroportin. We find that while both models maintain normal systemic iron homeostasis, they nonetheless develop fatal contractile and metabolic dysfunction as a consequence of cardiomyocyte iron deficiency. These findings are the first demonstration of a cell-autonomous role for hepcidin in iron homeostasis. They raise the possibility that such function may also be important in other tissues that express both hepcidin and ferroportin, such as the kidney and the brain. DOI:http://dx.doi.org/10.7554/eLife.19804.001 Many proteins inside cells require iron to work properly, and so this mineral is an essential part of the diets of most mammals. However, because too much iron in the body is also bad for health, mammals possess several proteins whose role is to maintain the balance of iron. Two proteins in particular, called hepcidin and ferroportin, are thought to be important in this process. Some ferroportin is found in the cells that line the gut (where iron is absorbed into the body) and is required to release this iron into the bloodstream. It is also found in the spleen, which is where iron is removed from old red blood cells so that it can be recycled. The liver produces hepcidin to control when ferroportin is active in the gut and spleen. Both hepcidin and ferroportin are also found in heart cells. In 2015, a study reported that that heart ferroportin plays an important role in heart activity. However, it was not clear what role hepcidin plays in this organ. Now, Lakhal-Littleton et al. – including many of the researchers from the previous work – have genetically engineered mice such that they specifically lacked heart hepcidin, or had a version of ferroportin in their heart that does not respond to hepcidin. The experiments show that these changes caused fatal heart failure in the mice because ferroportin releases iron from heart cells in an uncontrolled manner. Lakhal-Littleton et al. were able to prevent heart failure by injecting the animals with iron directly into the bloodstream. These findings show that hepcidin produced outside the liver has a role in controlling the levels of iron in the body’s organs. Other organs such as the brain, kidney and placenta all have their own forms of hepcidin and ferroportin; further work could investigate the roles of these proteins. Finally, another challenge for the future will be to test whether new drugs that are being developed to block or mimic hepcidin from the liver have the potential to treat heart conditions in humans. DOI:http://dx.doi.org/10.7554/eLife.19804.002
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Affiliation(s)
- Samira Lakhal-Littleton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Magda Wolna
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Yu Jin Chung
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Helen C Christian
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Marcella Brescia
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Vicky Ball
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Rebeca Diaz
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Ana Santos
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Daniel Biggs
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Benjamin Davies
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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28
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Glatz JF, Nabben M, Heather LC, Bonen A, Luiken JJ. Regulation of the subcellular trafficking of CD36, a major determinant of cardiac fatty acid utilization. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1461-71. [DOI: 10.1016/j.bbalip.2016.04.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 10/21/2022]
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Cole MA, Abd Jamil AH, Heather LC, Murray AJ, Sutton ER, Slingo M, Sebag-Montefiore L, Tan SC, Aksentijević D, Gildea OS, Stuckey DJ, Yeoh KK, Carr CA, Evans RD, Aasum E, Schofield CJ, Ratcliffe PJ, Neubauer S, Robbins PA, Clarke K. On the pivotal role of PPARα in adaptation of the heart to hypoxia and why fat in the diet increases hypoxic injury. FASEB J 2016; 30:2684-97. [PMID: 27103577 PMCID: PMC5072355 DOI: 10.1096/fj.201500094r] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 04/05/2016] [Indexed: 12/21/2022]
Abstract
The role of peroxisome proliferator-activated receptor α (PPARα)-mediated metabolic remodeling in cardiac adaptation to hypoxia has yet to be defined. Here, mice were housed in hypoxia for 3 wk before in vivo contractile function was measured using cine MRI. In isolated, perfused hearts, energetics were measured using (31)P magnetic resonance spectroscopy (MRS), and glycolysis and fatty acid oxidation were measured using [(3)H] labeling. Compared with a normoxic, chow-fed control mouse heart, hypoxia decreased PPARα expression, fatty acid oxidation, and mitochondrial uncoupling protein 3 (UCP3) levels, while increasing glycolysis, all of which served to maintain normal ATP concentrations ([ATP]) and thereby, ejection fractions. A high-fat diet increased cardiac PPARα expression, fatty acid oxidation, and UCP3 levels with decreased glycolysis. Hypoxia was unable to alter the high PPARα expression or reverse the metabolic changes caused by the high-fat diet, with the result that [ATP] and contractile function decreased significantly. The adaptive metabolic changes caused by hypoxia in control mouse hearts were found to have occurred already in PPARα-deficient (PPARα(-/-)) mouse hearts and sustained function in hypoxia despite an inability for further metabolic remodeling. We conclude that decreased cardiac PPARα expression is essential for adaptive metabolic remodeling in hypoxia, but is prevented by dietary fat.-Cole, M. A., Abd Jamil, A. H., Heather, L. C., Murray, A. J., Sutton, E. R., Slingo, M., Sebag-Montefiore, L., Tan, S. C., Aksentijević, D., Gildea, O. S., Stuckey, D. J., Yeoh, K. K., Carr, C. A., Evans, R. D., Aasum, E., Schofield, C. J., Ratcliffe, P. J., Neubauer, S., Robbins, P. A., Clarke, K. On the pivotal role of PPARα in adaptation of the heart to hypoxia and why fat in the diet increases hypoxic injury.
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Affiliation(s)
- Mark A Cole
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Amira H Abd Jamil
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Andrew J Murray
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Elizabeth R Sutton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Mary Slingo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Liam Sebag-Montefiore
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Suat Cheng Tan
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Dunja Aksentijević
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Ottilie S Gildea
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Daniel J Stuckey
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Kar Kheng Yeoh
- Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom; and
| | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Rhys D Evans
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Ellen Aasum
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Peter J Ratcliffe
- Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Stefan Neubauer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom;
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Slingo M, Cole M, Carr C, Curtis MK, Dodd M, Giles L, Heather LC, Tyler D, Clarke K, Robbins PA. The von Hippel-Lindau Chuvash mutation in mice alters cardiac substrate and high-energy phosphate metabolism. Am J Physiol Heart Circ Physiol 2016; 311:H759-67. [PMID: 27422990 PMCID: PMC5142182 DOI: 10.1152/ajpheart.00912.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 07/12/2016] [Indexed: 02/07/2023]
Abstract
This is the first integrative metabolic and functional study of the effects of modest hypoxia-inducible factor manipulation within the heart. Of particular note, the combination (and correlation) of perfused heart metabolic flux measurements with the new technique of real-time in vivo magnetic resonance spectroscopy using hyperpolarized pyruvate is a novel development. Hypoxia-inducible factor (HIF) appears to function as a global master regulator of cellular and systemic responses to hypoxia. HIF pathway manipulation is of therapeutic interest; however, global systemic upregulation of HIF may have as yet unknown effects on multiple processes. We used a mouse model of Chuvash polycythemia (CP), a rare genetic disorder that modestly increases expression of HIF target genes in normoxia, to understand what these effects might be within the heart. An integrated in and ex vivo approach was employed. Compared with wild-type controls, CP mice had evidence (using in vivo magnetic resonance imaging) of pulmonary hypertension, right ventricular hypertrophy, and increased left ventricular ejection fraction. Glycolytic flux (measured using [3H]glucose) in the isolated contracting perfused CP heart was 1.8-fold higher. Net lactate efflux was 1.5-fold higher. Furthermore, in vivo 13C-magnetic resonance spectroscopy (MRS) of hyperpolarized [13C1]pyruvate revealed a twofold increase in real-time flux through lactate dehydrogenase in the CP hearts and a 1.6-fold increase through pyruvate dehydrogenase. 31P-MRS of perfused CP hearts under increased workload (isoproterenol infusion) demonstrated increased depletion of phosphocreatine relative to ATP. Intriguingly, no changes in cardiac gene expression were detected. In summary, a modest systemic dysregulation of the HIF pathway resulted in clear alterations in cardiac metabolism and energetics. However, in contrast to studies generating high HIF levels within the heart, the CP mice showed neither the predicted changes in gene expression nor any degree of LV impairment. We conclude that the effects of manipulating HIF on the heart are dose dependent.
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Affiliation(s)
- Mary Slingo
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Mark Cole
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Carolyn Carr
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Mary K Curtis
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Michael Dodd
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Lucia Giles
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Damian Tyler
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Kieran Clarke
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter A Robbins
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
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Akhtar MZ, Huang H, Kaisar M, Lo Faro ML, Rebolledo R, Morten K, Heather LC, Dona A, Leuvenink HG, Fuggle SV, Kessler BM, Pugh CW, Ploeg RJ. Using an Integrated -Omics Approach to Identify Key Cellular Processes That Are Disturbed in the Kidney After Brain Death. Am J Transplant 2016; 16:1421-40. [PMID: 26602379 DOI: 10.1111/ajt.13626] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 10/26/2015] [Accepted: 11/12/2015] [Indexed: 01/25/2023]
Abstract
In an era where we are becoming more reliant on vulnerable kidneys for transplantation from older donors, there is an urgent need to understand how brain death leads to kidney dysfunction and, hence, how this can be prevented. Using a rodent model of hemorrhagic stroke and next-generation proteomic and metabolomic technologies, we aimed to delineate which key cellular processes are perturbed in the kidney after brain death. Pathway analysis of the proteomic signature of kidneys from brain-dead donors revealed large-scale changes in mitochondrial proteins that were associated with altered mitochondrial activity and morphological evidence of mitochondrial injury. We identified an increase in a number of glycolytic proteins and lactate production, suggesting a shift toward anaerobic metabolism. Higher amounts of succinate were found in the brain death group, in conjunction with increased markers of oxidative stress. We characterized the responsiveness of hypoxia inducible factors and found this correlated with post-brain death mean arterial pressures. Brain death leads to metabolic disturbances in the kidney and alterations in mitochondrial function and reactive oxygen species generation. This metabolic disturbance and alteration in mitochondrial function may lead to further cellular injury. Conditioning the brain-dead organ donor by altering metabolism could be a novel approach to ameliorate this brain death-induced kidney injury.
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Affiliation(s)
- M Z Akhtar
- Centre for Cellular and Molecular Physiology, Oxford University, Oxford, UK.,Oxford Transplant Centre, Nuffield Department of Surgical Sciences, Churchill Hospital, Oxford, UK
| | - H Huang
- Oxford Transplant Centre, Nuffield Department of Surgical Sciences, Churchill Hospital, Oxford, UK.,Target Discovery Institute, Oxford University, Oxford, UK
| | - M Kaisar
- Oxford Transplant Centre, Nuffield Department of Surgical Sciences, Churchill Hospital, Oxford, UK.,Target Discovery Institute, Oxford University, Oxford, UK
| | - M L Lo Faro
- Centre for Cellular and Molecular Physiology, Oxford University, Oxford, UK.,Oxford Transplant Centre, Nuffield Department of Surgical Sciences, Churchill Hospital, Oxford, UK
| | - R Rebolledo
- Surgical Research Laboratory, University of Groningen, Groningen, the Netherlands
| | - K Morten
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, UK
| | - L C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - A Dona
- Department of Surgery, Imperial College, London, UK.,Kolling Institute for Medical Research, The University of Sydney, New South Wales, Australia
| | - H G Leuvenink
- Surgical Research Laboratory, University of Groningen, Groningen, the Netherlands
| | - S V Fuggle
- Oxford Transplant Centre, Nuffield Department of Surgical Sciences, Churchill Hospital, Oxford, UK
| | - B M Kessler
- Target Discovery Institute, Oxford University, Oxford, UK
| | - C W Pugh
- Centre for Cellular and Molecular Physiology, Oxford University, Oxford, UK
| | - R J Ploeg
- Oxford Transplant Centre, Nuffield Department of Surgical Sciences, Churchill Hospital, Oxford, UK
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Mansor LS, Mehta K, Aksentijevic D, Carr CA, Lund T, Cole MA, Le Page L, Sousa Fialho MDL, Shattock MJ, Aasum E, Clarke K, Tyler DJ, Heather LC. Increased oxidative metabolism following hypoxia in the type 2 diabetic heart, despite normal hypoxia signalling and metabolic adaptation. J Physiol 2015; 594:307-20. [PMID: 26574233 DOI: 10.1113/jp271242] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 11/10/2015] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS Adaptation to hypoxia makes the heart more oxygen efficient, by metabolising more glucose. In contrast, type 2 diabetes makes the heart metabolise more fatty acids. Diabetes increases the chances of the heart being exposed to hypoxia, but whether the diabetic heart can adapt and respond is unknown. In this study we show that diabetic hearts retain the ability to adapt their metabolism in response to hypoxia, with functional hypoxia signalling pathways. However, the hypoxia-induced changes in metabolism are additive to abnormal baseline metabolism, resulting in hypoxic diabetic hearts metabolising more fat and less glucose than controls. This stops the diabetic heart being able to recover its function when stressed. These results demonstrate that the diabetic heart retains metabolic flexibility to adapt to hypoxia, but is hindered by the baseline effects of the disease. This increases our understanding of how the diabetic heart is affected by hypoxia-associated complications of the disease. ABSTRACT Hypoxia activates the hypoxia-inducible factor (HIF), promoting glycolysis and suppressing mitochondrial respiration. In the type 2 diabetic heart, glycolysis is suppressed whereas fatty acid metabolism is promoted. The diabetic heart experiences chronic hypoxia as a consequence of increased obstructive sleep apnoea and cardiovascular disease. Given the opposing metabolic effects of hypoxia and diabetes, we questioned whether diabetes affects cardiac metabolic adaptation to hypoxia. Control and type 2 diabetic rats were housed for 3 weeks in normoxia or 11% oxygen. Metabolism and function were measured in the isolated perfused heart using radiolabelled substrates. Following chronic hypoxia, both control and diabetic hearts upregulated glycolysis, lactate efflux and glycogen content and decreased fatty acid oxidation rates, with similar activation of HIF signalling pathways. However, hypoxia-induced changes were superimposed on diabetic hearts that were metabolically abnormal in normoxia, resulting in glycolytic rates 30% lower, and fatty acid oxidation 36% higher, in hypoxic diabetic hearts than hypoxic controls. Peroxisome proliferator-activated receptor α target proteins were suppressed by hypoxia, but activated by diabetes. Mitochondrial respiration in diabetic hearts was divergently activated following hypoxia compared with controls. These differences in metabolism were associated with decreased contractile recovery of the hypoxic diabetic heart following an acute hypoxic insult. In conclusion, type 2 diabetic hearts retain metabolic flexibility to adapt to hypoxia, with normal HIF signalling pathways. However, they are more dependent on oxidative metabolism following hypoxia due to abnormal normoxic metabolism, which was associated with a functional deficit in response to stress.
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Affiliation(s)
- Latt S Mansor
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Keshavi Mehta
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Dunja Aksentijevic
- British Heart Foundation Centre of Research Excellence, King's College London, The Rayne Institute, London, UK
| | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Trine Lund
- Department of Medical Biology, University of Tromso, Norway
| | - Mark A Cole
- University of Nottingham Medical School, Queens Medical Centre, Nottingham, UK
| | - Lydia Le Page
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | | | - Michael J Shattock
- British Heart Foundation Centre of Research Excellence, King's College London, The Rayne Institute, London, UK
| | - Ellen Aasum
- Department of Medical Biology, University of Tromso, Norway
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Fialho MS, Mansor LM, Yea G, Evans RD, Coumans WA, Luiken JJ, Glatz J, Tyler DJ, Heather LC. 2 Pharmacological inhibition of sarcolemmal fatty acid uptake provides a novel mechanism to improve metabolism and function in the type 2 diabetic heart. Heart 2015. [DOI: 10.1136/heartjnl-2015-308734.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Le Page LM, Rider OJ, Lewis AJ, Ball V, Clarke K, Johansson E, Carr CA, Heather LC, Tyler DJ. Increasing Pyruvate Dehydrogenase Flux as a Treatment for Diabetic Cardiomyopathy: A Combined 13C Hyperpolarized Magnetic Resonance and Echocardiography Study. Diabetes 2015; 64:2735-43. [PMID: 25795215 PMCID: PMC4516266 DOI: 10.2337/db14-1560] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 03/16/2015] [Indexed: 01/02/2023]
Abstract
Although diabetic cardiomyopathy is widely recognized, there are no specific treatments available. Altered myocardial substrate selection has emerged as a candidate mechanism behind the development of cardiac dysfunction in diabetes. As pyruvate dehydrogenase (PDH) activity appears central to the balance of substrate use, we aimed to investigate the relationship between PDH flux and myocardial function in a rodent model of type 2 diabetes and to explore whether or not increasing PDH flux, with dichloroacetate, would restore the balance of substrate use and improve cardiac function. All animals underwent in vivo hyperpolarized [1-(13)C]pyruvate magnetic resonance spectroscopy and echocardiography to assess cardiac PDH flux and function, respectively. Diabetic animals showed significantly higher blood glucose levels (10.8 ± 0.7 vs. 8.4 ± 0.5 mmol/L), lower PDH flux (0.005 ± 0.001 vs. 0.017 ± 0.002 s(-1)), and significantly impaired diastolic function (transmitral early diastolic peak velocity/early diastolic myocardial velocity ratio [E/E'] 12.2 ± 0.8 vs. 20 ± 2), which are in keeping with early diabetic cardiomyopathy. Twenty-eight days of treatment with dichloroacetate restored PDH flux to normal levels (0.018 ± 0.002 s(-1)), reversed diastolic dysfunction (E/E' 14 ± 1), and normalized blood glucose levels (7.5 ± 0.7 mmol/L). The treatment of diabetes with dichloroacetate therefore restored the balance of myocardial substrate selection, reversed diastolic dysfunction, and normalized blood glucose levels. This suggests that PDH modulation could be a novel therapy for the treatment and/or prevention of diabetic cardiomyopathy.
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Affiliation(s)
- Lydia M Le Page
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Oliver J Rider
- Division of Cardiovascular Medicine, University of Oxford, Oxford, U.K
| | - Andrew J Lewis
- Division of Cardiovascular Medicine, University of Oxford, Oxford, U.K
| | - Vicky Ball
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | | | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K.
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Tan SC, Gomes RSM, Yeoh KK, Perbellini F, Malandraki-Miller S, Ambrose L, Heather LC, Faggian G, Schofield CJ, Davies KE, Clarke K, Carr CA. Preconditioning of Cardiosphere-Derived Cells With Hypoxia or Prolyl-4-Hydroxylase Inhibitors Increases Stemness and Decreases Reliance on Oxidative Metabolism. Cell Transplant 2015; 25:35-53. [PMID: 25751158 PMCID: PMC6042641 DOI: 10.3727/096368915x687697] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cardiosphere-derived cells (CDCs), which can be isolated from heart explants, are a promising candidate cell source for infarcted myocardium regeneration. However, current protocols used to expand CDCs require at least 1 month in vitro to obtain sufficient cells for transplantation. We report that CDC culture can be optimized by preconditioning the cells under hypoxia (2% oxygen), which may reflect the physiological oxygen level of the stem cell niche. Under hypoxia, the CDC proliferation rate increased by 1.4-fold, generating 6 × 10(6) CDCs with higher expression of cardiac stem cell and pluripotency gene markers compared to normoxia. Furthermore, telomerase (TERT), cytokines/ligands involved in stem cell trafficking (SDF/CXCR-4), erythropoiesis (EPO), and angiogenesis (VEGF) were increased under hypoxia. Hypoxic preconditioning was mimicked by treatment with two types of hypoxia-inducible factor (HIF) prolyl-4-hydroxylase inhibitors (PHDIs): dimethyloxaloylglycine (DMOG) and 2-(1-chloro-4-hydroxyisoquinoline-3-carboxamido) acetic acid (BIC). Despite the difference in specificity, both PHDIs significantly increased c-Kit expression and activated HIF, EPO, and CXCR-4. Furthermore, treatment with PHDIs for 24 h increased cell proliferation. Notably, all hypoxic and PHDI-preconditioned CDCs had decreased oxygen consumption and increased glycolytic metabolism. In conclusion, cells cultured under hypoxia could have potentially enhanced therapeutic potential, which can be mimicked, in part, by PHDIs.
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Affiliation(s)
- Suat Cheng Tan
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
- School of Health Science, Health Campus, Universiti Sains Malaysia, Kelantan, Malaysia
| | - Renata S. M. Gomes
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Kar Kheng Yeoh
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, UK
- School of Chemical Science, Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Filippo Perbellini
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
- Department of Cardiac Surgery, University of Verona, Verona, Italy
| | | | - Lucy Ambrose
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Lisa C. Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Giuseppe Faggian
- Department of Cardiac Surgery, University of Verona, Verona, Italy
| | | | - Kay E. Davies
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Carolyn A. Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Dodd MS, Atherton HJ, Carr CA, Stuckey DJ, West JA, Griffin JL, Radda GK, Clarke K, Heather LC, Tyler DJ. Impaired in vivo mitochondrial Krebs cycle activity after myocardial infarction assessed using hyperpolarized magnetic resonance spectroscopy. Circ Cardiovasc Imaging 2014; 7:895-904. [PMID: 25201905 DOI: 10.1161/circimaging.114.001857] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Myocardial infarction (MI) is one of the leading causes of heart failure. An increasing body of evidence links alterations in cardiac metabolism and mitochondrial function with the progression of heart disease. The aim of this work was to, therefore, follow the in vivo mitochondrial metabolic alterations caused by MI, thereby allowing a greater understanding of the interplay between metabolic and functional abnormalities. METHODS AND RESULTS Using hyperpolarized carbon-13 ((13)C)-magnetic resonance spectroscopy, in vivo alterations in mitochondrial metabolism were assessed for 22 weeks after surgically induced MI with reperfusion in female Wister rats. One week after MI, there were no detectable alterations in in vivo cardiac mitochondrial metabolism over the range of ejection fractions observed (from 28% to 84%). At 6 weeks after MI, in vivo mitochondrial Krebs cycle activity was impaired, with decreased (13)C-label flux into citrate, glutamate, and acetylcarnitine, which correlated with the degree of cardiac dysfunction. These changes were independent of alterations in pyruvate dehydrogenase flux. By 22 weeks, alterations were also seen in pyruvate dehydrogenase flux, which decreased at lower ejection fractions. These results were confirmed using in vitro analysis of enzyme activities and metabolomic profiles of key intermediates. CONCLUSIONS The in vivo decrease in Krebs cycle activity in the 6-week post-MI heart may represent an early maladaptive phase in the metabolic alterations after MI in which reductions in Krebs cycle activity precede a reduction in pyruvate dehydrogenase flux. Changes in mitochondrial metabolism in heart disease are progressive and proportional to the degree of cardiac impairment.
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Affiliation(s)
- Michael S Dodd
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Helen J Atherton
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Carolyn A Carr
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Daniel J Stuckey
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - James A West
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Julian L Griffin
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - George K Radda
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Kieran Clarke
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Lisa C Heather
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Damian J Tyler
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
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Ashmore T, Fernandez BO, Branco-Price C, West JA, Cowburn AS, Heather LC, Griffin JL, Johnson RS, Feelisch M, Murray AJ. Dietary nitrate increases arginine availability and protects mitochondrial complex I and energetics in the hypoxic rat heart. J Physiol 2014; 592:4715-31. [PMID: 25172947 PMCID: PMC4253472 DOI: 10.1113/jphysiol.2014.275263] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Hypoxic exposure is associated with impaired cardiac energetics in humans and altered mitochondrial function, with suppressed complex I-supported respiration, in rat heart. This response might limit reactive oxygen species generation, but at the cost of impaired electron transport chain (ETC) activity. Dietary nitrate supplementation improves mitochondrial efficiency and can promote tissue oxygenation by enhancing blood flow. We therefore hypothesised that ETC dysfunction, impaired energetics and oxidative damage in the hearts of rats exposed to chronic hypoxia could be alleviated by sustained administration of a moderate dose of dietary nitrate. Male Wistar rats (n = 40) were given water supplemented with 0.7 mmol l−1 NaCl (as control) or 0.7 mmol l−1 NaNO3, elevating plasma nitrate levels by 80%, and were exposed to 13% O2 (hypoxia) or normoxia (n = 10 per group) for 14 days. Respiration rates, ETC protein levels, mitochondrial density, ATP content and protein carbonylation were measured in cardiac muscle. Complex I respiration rates and protein levels were 33% lower in hypoxic/NaCl rats compared with normoxic/NaCl controls. Protein carbonylation was 65% higher in hearts of hypoxic rats compared with controls, indicating increased oxidative stress, whilst ATP levels were 62% lower. Respiration rates, complex I protein and activity, protein carbonylation and ATP levels were all fully protected in the hearts of nitrate-supplemented hypoxic rats. Both in normoxia and hypoxia, dietary nitrate suppressed cardiac arginase expression and activity and markedly elevated cardiac l-arginine concentrations, unmasking a novel mechanism of action by which nitrate enhances tissue NO bioavailability. Dietary nitrate therefore alleviates metabolic abnormalities in the hypoxic heart, improving myocardial energetics.
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Affiliation(s)
- Tom Ashmore
- Department of Physiology, Development & Neuroscience, University of Cambridge, UK Department of Biochemistry, University of Cambridge, UK
| | | | | | - James A West
- Department of Biochemistry, University of Cambridge, UK MRC-Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK
| | - Andrew S Cowburn
- Department of Physiology, Development & Neuroscience, University of Cambridge, UK
| | - Lisa C Heather
- Department of Physiology, Anatomy & Genetics, University of Oxford, UK
| | - Julian L Griffin
- Department of Biochemistry, University of Cambridge, UK MRC-Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK
| | - Randall S Johnson
- Department of Physiology, Development & Neuroscience, University of Cambridge, UK
| | - Martin Feelisch
- Faculty of Medicine, Clinical & Experimental Sciences, University of Southampton, UK
| | - Andrew J Murray
- Department of Physiology, Development & Neuroscience, University of Cambridge, UK
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Ambrose LJA, Abd-Jamil AH, Gomes RSM, Carter EE, Carr CA, Clarke K, Heather LC. Investigating mitochondrial metabolism in contracting HL-1 cardiomyocytes following hypoxia and pharmacological HIF activation identifies HIF-dependent and independent mechanisms of regulation. J Cardiovasc Pharmacol Ther 2014; 19:574-85. [PMID: 24607765 DOI: 10.1177/1074248414524480] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Hypoxia is a consequence of cardiac disease and downregulates mitochondrial metabolism, yet the molecular mechanisms through which this occurs in the heart are incompletely characterized. Therefore, we aimed to use a contracting HL-1 cardiomyocyte model to investigate the effects of hypoxia on mitochondrial metabolism. Cells were exposed to hypoxia (2% O2) for 6, 12, 24, and 48 hours to characterize the metabolic response. Cells were subsequently treated with the hypoxia inducible factor (HIF)-activating compound, dimethyloxalylglycine (DMOG), to determine whether hypoxia-induced mitochondrial changes were HIF dependent or independent, and to assess the suitability of this cultured cardiac cell line for cardiovascular pharmacological studies. Hypoxic cells had increased glycolysis after 24 hours, with glucose transporter 1 and lactate levels increased 5-fold and 15-fold, respectively. After 24 hours of hypoxia, mitochondrial networks were more fragmented but there was no change in citrate synthase activity, indicating that mitochondrial content was unchanged. Cellular oxygen consumption was 30% lower, accompanied by decreases in the enzymatic activities of electron transport chain (ETC) complexes I and IV, and aconitase by 81%, 96%, and 72%, relative to controls. Pharmacological HIF activation with DMOG decreased cellular oxygen consumption by 43%, coincident with decreases in the activities of aconitase and complex I by 26% and 30%, indicating that these adaptations were HIF mediated. In contrast, the hypoxia-mediated decrease in complex IV activity was not replicated by DMOG treatment, suggesting HIF-independent regulation of this complex. In conclusion, 24 hours of hypoxia increased anaerobic glycolysis and decreased mitochondrial respiration, which was associated with changes in ETC and tricarboxylic acid cycle enzyme activities in contracting HL-1 cells. Pharmacological HIF activation in this cardiac cell line allowed both HIF-dependent and independent mitochondrial metabolic changes to be identified.
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Affiliation(s)
- Lucy J A Ambrose
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Amira H Abd-Jamil
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Renata S M Gomes
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Emma E Carter
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
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Mansor LS, Gonzalez ER, Cole MA, Tyler DJ, Beeson JH, Clarke K, Carr CA, Heather LC. Cardiac metabolism in a new rat model of type 2 diabetes using high-fat diet with low dose streptozotocin. Cardiovasc Diabetol 2013; 12:136. [PMID: 24063408 PMCID: PMC3849358 DOI: 10.1186/1475-2840-12-136] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 09/19/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To study the pathogenesis of diabetic cardiomyopathy, reliable animal models of type 2 diabetes are required. Physiologically relevant rodent models are needed, which not only replicate the human pathology but also mimic the disease process. Here we characterised cardiac metabolic abnormalities, and investigated the optimal experimental approach for inducing disease, in a new model of type 2 diabetes. METHODS AND RESULTS Male Wistar rats were fed a high-fat diet for three weeks, with a single intraperitoneal injection of low dose streptozotocin (STZ) after fourteen days at 15, 20, 25 or 30 mg/kg body weight. Compared with chow-fed or high-fat diet fed control rats, a high-fat diet in combination with doses of 15-25 mg/kg STZ did not change insulin concentrations and rats maintained body weight. In contrast, 30 mg/kg STZ induced hypoinsulinaemia, hyperketonaemia and weight loss. There was a dose-dependent increase in blood glucose and plasma lipids with increasing concentrations of STZ. Cardiac and hepatic triglycerides were increased by all doses of STZ, in contrast, cardiac glycogen concentrations increased in a dose-dependent manner with increasing STZ concentrations. Cardiac glucose transporter 4 protein levels were decreased, whereas fatty acid metabolism-regulated proteins, including uncoupling protein 3 and pyruvate dehydrogenase (PDH) kinase 4, were increased with increasing doses of STZ. Cardiac PDH activity displayed a dose-dependent relationship between enzyme activity and STZ concentration. Cardiac insulin-stimulated glycolytic rates were decreased by 17% in 15 mg/kg STZ high-fat fed diabetic rats compared with control rats, with no effect on cardiac contractile function. CONCLUSIONS High-fat feeding in combination with a low dose of STZ induced cardiac metabolic changes that mirror the decrease in glucose metabolism and increase in fat metabolism in diabetic patients. While low doses of 15-25 mg/kg STZ induced a type 2 diabetic phenotype, higher doses more closely recapitulated type 1 diabetes, demonstrating that the severity of diabetes can be modified according to the requirements of the study.
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Affiliation(s)
- Latt S Mansor
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, Oxford, UK
| | - Eileen R Gonzalez
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, Oxford, UK
| | - Mark A Cole
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, Oxford, UK
- University of Nottingham Medical School, Queens Medical Centre, Nottingham, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, Oxford, UK
| | - Jessica H Beeson
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, Oxford, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, Oxford, UK
| | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, Oxford, UK
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, OX1 3PT, Oxford, UK
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Heather LC, Pates KM, Atherton HJ, Cole MA, Ball DR, Evans RD, Glatz JF, Luiken JJ, Griffin JL, Clarke K. Differential translocation of the fatty acid transporter, FAT/CD36, and the glucose transporter, GLUT4, coordinates changes in cardiac substrate metabolism during ischemia and reperfusion. Circ Heart Fail 2013; 6:1058-66. [PMID: 23940308 DOI: 10.1161/circheartfailure.112.000342] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Fatty acid and glucose transporters translocate between the sarcolemma and intracellular compartments to regulate substrate metabolism acutely. We hypothesised that during ischemia fatty acid translocase (FAT/CD36) would translocate away from the sarcolemma to limit fatty acid uptake when fatty acid oxidation is inhibited. METHODS AND RESULTS Wistar rat hearts were perfused during preischemia, low-flow ischemia, and reperfusion, using (3)H-substrates for measurement of metabolic rates, followed by metabolomic analysis and subcellular fractionation. During ischemia, there was a 32% decrease in sarcolemmal FAT/CD36 accompanied by a 95% decrease in fatty acid oxidation rates, with no change in intramyocardial lipids. Concomitantly, the sarcolemmal content of the glucose transporter, GLUT4, increased by 90% during ischemia, associated with an 86% increase in glycolytic rates, 45% decrease in glycogen content, and a 3-fold increase in phosphorylated AMP-activated protein kinase. Following reperfusion, decreased sarcolemmal FAT/CD36 persisted, but fatty acid oxidation rates returned to preischemic levels, resulting in a 35% decrease in myocardial triglyceride content. Elevated sarcolemmal GLUT4 persisted during reperfusion; in contrast, glycolytic rates decreased to 30% of preischemic rates, accompanied by a 5-fold increase in intracellular citrate levels and restoration of glycogen content. CONCLUSIONS During ischemia, FAT/CD36 moved away from the sarcolemma as GLUT4 moved toward the sarcolemma, associated with a shift from fatty acid oxidation to glycolysis, while intramyocardial lipid accumulation was prevented. This relocation was maintained during reperfusion, which was associated with replenishing glycogen stores as a priority, occurring at the expense of glycolysis and mediated by an increase in citrate levels.
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Affiliation(s)
- Lisa C Heather
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy, and Genetics, University of Oxford, UK
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Heather LC, Wang X, West JA, Griffin JL. A practical guide to metabolomic profiling as a discovery tool for human heart disease. J Mol Cell Cardiol 2013; 55:2-11. [DOI: 10.1016/j.yjmcc.2012.12.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 11/30/2012] [Accepted: 12/01/2012] [Indexed: 12/12/2022]
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Dodd MS, Ball DR, Schroeder MA, Le Page LM, Atherton HJ, Heather LC, Seymour AM, Ashrafian H, Watkins H, Clarke K, Tyler DJ. In vivo alterations in cardiac metabolism and function in the spontaneously hypertensive rat heart. Cardiovasc Res 2012; 95:69-76. [PMID: 22593200 DOI: 10.1093/cvr/cvs164] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS The aim of this work was to use hyperpolarized carbon-13 ((13)C) magnetic resonance (MR) spectroscopy and cine MR imaging (MRI) to assess in vivo cardiac metabolism and function in the 15-week-old spontaneously hypertensive rat (SHR) heart. At this time point, the SHR displays hypertension and concentric hypertrophy. One of the cellular adaptations to hypertrophy is a reduction in β-oxidation, and it has previously been shown that in response to hypertrophy the SHR heart switches to a glycolytic/glucose-oxidative phenotype. METHODS AND RESULTS Cine-MRI (magnetic resonance imaging) was used to assess cardiac function and degree of cardiac hypertrophy. Wistar rats were used as controls. SHRs displayed functional changes in stroke volume, heart rate, and late peak-diastolic filling alongside significant hypertrophy (a 56% increase in left ventricular mass). Using hyperpolarized [1-(13)C] and [2-(13)C]pyruvate, an 85% increase in (13)C label flux through pyruvate dehydrogenase (PDH) was seen in the SHR heart and (13)C label incorporation into citrate, acetylcarnitine, and glutamate pools was elevated in proportion to the increase in PDH flux. These findings were confirmed using biochemical analysis of PDH activity and protein expression of PDH regulatory enzymes. CONCLUSIONS Functional and structural alterations in the SHR heart are consistent with the hypertrophied phenotype. Our in vivo work indicates a preference for glucose metabolism in the SHR heart, a move away from predominantly fatty acid oxidative metabolism. Interestingly, (13)C label flux into lactate was unchanged, indicating no switch to an anaerobic glycolytic phenotype, but rather an increased reliance on glucose oxidation in the SHR heart.
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Affiliation(s)
- Michael S Dodd
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Parks Road, Oxford, UK
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Tan SC, Carr CA, Yeoh KK, Heather LC, Ambrose L, Schofield C, Clarke K. Abstract P027: Preconditioning Cardiosphere-Derived Cells by Hypoxia and Prolyl Hydroxylase Inhibitors to Induce HIF-Related Metabolic Changes and C-Kit Expression. Circ Res 2011. [DOI: 10.1161/res.109.suppl_1.ap027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cardiosphere-derived cells (CDCs) decrease loss of cardiac function following infarction, but the potential of CDC therapy is limited due to the low retention rate and the time required to obtain sufficient cells for transplantation.
AIM: Here, we aimed to precondition CDCs by culturing under hypoxia, or with prolyl hydroxylase inhibitors (PHIs), to prepare the cells for the hypoxic environment within the infarcted heart.
METHODS: Rat heart explants were cultured under hypoxia (2% O2) or normoxia (21% O2) to generate explant-derived cells (EDC). EDCs were isolated, cultured to form cardiosphere and expanded into monolayer CDCs. At 80% confluency, normoxic CDCs were treated with dimethyloxalyl glycine (DMOG), Ethyl 2-(2,3-dihyroxybenzamido) (KKC226) and FG-2216 for 24 h.
RESULTS: Hypoxia, 1 mM DMOG, 0.5 mM KKC226 and 30 μM FG-2216 treated CDCs showed significantly increased HIF-1α protein expression (3.9-fold, 2.6-fold, 2.1-fold and 1.5-fold, respectively) and reduced oxygen consumption (81%, 32%, 47% and 35%, respectively), compared with normoxic CDCs. Hypoxia and PHI treatment increased protein levels of GLUT-1 (6.7-fold, 3.2-fold, 4.0-fold and 2.1-fold, respectively), resulting in significant increases in glucose uptake and lactate accumulation in the culture medium, compared with controls, commensurate with increased glycolytic metabolism after hypoxia or PHI treatment. Further, hypoxia and KKC226 increased c-Kit mRNA expression 5.1-fold and 1.5-fold, respectively. qRT-PCR confirmed increased CXCR-4 mRNA in all hypoxia and PHI-treated CDCs. EDC and CDC proliferation were 1.7-fold faster under hypoxia, compared with normoxia, but did not increase with PHI treatment.
CONCLUSION: Hypoxia and PHIs stabilized and activated HIF, which induced metabolic changes in CDCs, including GLUT-1 upregulation and a switch to anaerobic glycolytic metabolism. All preconditioned cells had reduced oxygen consumption and were better adapted to survive within an hypoxic infarct scar. HIF-induced upregulation of CXCR-4 may increase the homing of these cells to the infarcted myocardium. Finally, increased proliferation and expression of the cardiac stem cell marker, c-Kit, could decrease the time required for cell expansion prior to therapy by a week.
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Schroeder MA, Atherton HJ, Heather LC, Griffin JL, Clarke K, Radda GK, Tyler DJ. Determining the in vivo regulation of cardiac pyruvate dehydrogenase based on label flux from hyperpolarised [1-13C]pyruvate. NMR Biomed 2011; 24:980-987. [PMID: 21387444 PMCID: PMC4604660 DOI: 10.1002/nbm.1668] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 11/28/2010] [Accepted: 12/13/2010] [Indexed: 05/15/2023]
Abstract
Pyruvate dehydrogenase (PDH) is a key regulator of cardiac substrate selection and is regulated by both pyruvate dehydrogenase kinase (PDK)-mediated phosphorylation and feedback inhibition. The extent to which chronic upregulation of PDK protein levels, acutely increased PDK activity and acute feedback inhibition limit PDH flux remains unclear because existing in vitro assessment methods inherently disrupt the regulation of the enzyme complex. We have demonstrated previously that hyperpolarised (13)C-labelled metabolic tracers coupled with MRS can monitor flux through PDH in vivo. The aim of this study was to determine the relative contributions of acute and chronic changes in PDK and PDH activities to in vivo myocardial PDH flux. We examined both fed and fasted rats with either hyperpolarised [1-(13)C]pyruvate alone or hyperpolarised [1-(13)C]pyruvate co-infused with malate [to modulate mitochondrial nicotinamide adenine dinucleotide (NADH/NAD(+)) and acetyl-coenzyme A (acetyl-CoA)/CoA ratios, which alter both PDH activity and flux]. To confirm the metabolic fate of infused malate, we performed in vitro (1)H NMR spectroscopy on cardiac tissue extracts. We observed that, in fed rats, where PDH activity was high, the presence of malate increased PDH flux by 27%, whereas, in the fasted state, malate infusion had no effect on PDH flux. These observations suggest that pyruvate oxidation is limited by feedback inhibition from acetyl-CoA only when PDH activity is high. Therefore, in the case of PDH, and potentially other enzymes, hyperpolarised (13)C MRI can be used to assess noninvasively enzymatic regulation.
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Affiliation(s)
- Marie A. Schroeder
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford
| | - Helen J. Atherton
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford
- Department of Biochemistry, University of Cambridge
| | - Lisa C. Heather
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford
| | | | - Kieran Clarke
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford
| | - George K. Radda
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford
| | - Damian J. Tyler
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford
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Atherton HJ, Dodd MS, Heather LC, Schroeder MA, Griffin JL, Radda GK, Clarke K, Tyler DJ. Role of pyruvate dehydrogenase inhibition in the development of hypertrophy in the hyperthyroid rat heart: a combined magnetic resonance imaging and hyperpolarized magnetic resonance spectroscopy study. Circulation 2011; 123:2552-61. [PMID: 21606392 DOI: 10.1161/circulationaha.110.011387] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Hyperthyroidism increases heart rate, contractility, cardiac output, and metabolic rate. It is also accompanied by alterations in the regulation of cardiac substrate use. Specifically, hyperthyroidism increases the ex vivo activity of pyruvate dehydrogenase kinase, thereby inhibiting glucose oxidation via pyruvate dehydrogenase. Cardiac hypertrophy is another effect of hyperthyroidism, with an increase in the abundance of mitochondria. Although the hypertrophy is initially beneficial, it can eventually lead to heart failure. The aim of this study was to use hyperpolarized magnetic resonance spectroscopy to investigate the rate and regulation of in vivo pyruvate dehydrogenase flux in the hyperthyroid heart and to establish whether modulation of flux through pyruvate dehydrogenase would alter cardiac hypertrophy. METHODS AND RESULTS Hyperthyroidism was induced in 18 male Wistar rats with 7 daily intraperitoneal injections of freshly prepared triiodothyronine (0.2 mg x kg(-1) x d(-1)). In vivo pyruvate dehydrogenase flux, assessed with hyperpolarized magnetic resonance spectroscopy, was reduced by 59% in hyperthyroid animals (0.0022 ± 0.0002 versus 0.0055 ± 0.0005 second(-1); P=0.0003), and this reduction was completely reversed by both short- and long-term delivery of dichloroacetic acid, a pyruvate dehydrogenase kinase inhibitor. Hyperpolarized [2-(13)C]pyruvate was also used to evaluate Krebs cycle metabolism and demonstrated a unique marker of anaplerosis, the level of which was significantly increased in the hyperthyroid heart. Cine magnetic resonance imaging showed that long-term dichloroacetic acid treatment significantly reduced the hypertrophy observed in hyperthyroid animals (100 ± 20 versus 200 ± 30 mg; P=0.04) despite no change in the increase observed in cardiac output. CONCLUSIONS This work has demonstrated that inhibition of glucose oxidation in the hyperthyroid heart in vivo is mediated by pyruvate dehydrogenase kinase. Relieving this inhibition can increase the metabolic flexibility of the hyperthyroid heart and reduce the level of hypertrophy that develops while maintaining the increased cardiac output required to meet the higher systemic metabolic demand.
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Affiliation(s)
- Helen J Atherton
- Department of Biochemistry, Sanger Bldg, University of Cambridge, Tennis Court Rd, Cambridge CB2 1GA, UK.
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Cole MA, Murray AJ, Cochlin LE, Heather LC, McAleese S, Knight NS, Sutton E, Jamil AA, Parassol N, Clarke K. A high fat diet increases mitochondrial fatty acid oxidation and uncoupling to decrease efficiency in rat heart. Basic Res Cardiol 2011; 106:447-57. [PMID: 21318295 PMCID: PMC3071466 DOI: 10.1007/s00395-011-0156-1] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/12/2010] [Accepted: 12/23/2010] [Indexed: 12/03/2022]
Abstract
Elevated levels of cardiac mitochondrial uncoupling protein 3 (UCP3) and decreased cardiac efficiency (hydraulic power/oxygen consumption) with abnormal cardiac function occur in obese, diabetic mice. To determine whether cardiac mitochondrial uncoupling occurs in non-genetic obesity, we fed rats a high fat diet (55% kcal from fat) or standard laboratory chow (7% kcal from fat) for 3 weeks, after which we measured cardiac function in vivo using cine MRI, efficiency in isolated working hearts and respiration rates and ADP/O ratios in isolated interfibrillar mitochondria; also, measured were medium chain acyl-CoA dehydrogenase (MCAD) and citrate synthase activities plus uncoupling protein 3 (UCP3), mitochondrial thioesterase 1 (MTE-1), adenine nucleotide translocase (ANT) and ATP synthase protein levels. We found that in vivo cardiac function was the same for all rats, yet oxygen consumption was 19% higher in high fat-fed rat hearts, therefore, efficiency was 21% lower than in controls. We found that mitochondrial fatty acid oxidation rates were 25% higher, and MCAD activity was 23% higher, in hearts from rats fed the high fat diet when compared with controls. Mitochondria from high fat-fed rat hearts had lower ADP/O ratios than controls, indicating increased respiratory uncoupling, which was ameliorated by GDP, a UCP3 inhibitor. Mitochondrial UCP3 and MTE-1 levels were both increased by 20% in high fat-fed rat hearts when compared with controls, with no significant change in ATP synthase or ANT levels, or citrate synthase activity. We conclude that increased cardiac oxygen utilisation, and thereby decreased cardiac efficiency, occurs in non-genetic obesity, which is associated with increased mitochondrial uncoupling due to elevated UCP3 and MTE-1 levels.
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Affiliation(s)
- Mark A Cole
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
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48
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Atherton HJ, Schroeder MA, Dodd MS, Heather LC, Carter EE, Cochlin LE, Nagel S, Sibson NR, Radda GK, Clarke K, Tyler DJ. Validation of the in vivo assessment of pyruvate dehydrogenase activity using hyperpolarised 13C MRS. NMR Biomed 2011; 24:201-208. [PMID: 20799252 PMCID: PMC4604661 DOI: 10.1002/nbm.1573] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 04/19/2010] [Accepted: 05/11/2010] [Indexed: 05/05/2023]
Abstract
Many diseases of the heart are characterised by changes in substrate utilisation, which is regulated in part by the activity of the enzyme pyruvate dehydrogenase (PDH). Consequently, there is much interest in the in vivo evaluation of PDH activity in a range of physiological and pathological states to obtain information on the metabolic mechanisms of cardiac diseases. Hyperpolarised [1-(13)C]pyruvate, detected using MRS, is a novel technique for the noninvasive evaluation of PDH flux. PDH flux has been assumed to directly reflect in vivo PDH activity, although to date this assumption remains unproven. Control animals and animals undergoing interventions known to modulate PDH activity, namely high fat feeding and dichloroacetate infusion, were used to investigate the relationship between in vivo hyperpolarised MRS measurements of PDH flux and ex vivo measurements of PDH enzyme activity (PDH(a)). Further, the plasma concentrations of pyruvate and other important metabolites were evaluated following pyruvate infusion to assess the metabolic consequences of pyruvate infusion during hyperpolarised MRS experiments. Hyperpolarised MRS measurements of PDH flux correlated significantly with ex vivo measurements of PDH(a), confirming that PDH activity influences directly the in vivo flux of hyperpolarised pyruvate through cardiac PDH. The maximum plasma concentration of pyruvate reached during hyperpolarised MRS experiments was approximately 250 µM, equivalent to physiological pyruvate concentrations reached during exercise or with dietary interventions. The concentrations of other metabolites, including lactate, glucose and β-hydroxybutyrate, did not vary during the 60 s following pyruvate infusion. Hence, during the 60-s data acquisition period, metabolism was minimally affected by pyruvate infusion.
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Affiliation(s)
- Helen J Atherton
- Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Marie A Schroeder
- Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Michael S Dodd
- Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Emma E Carter
- Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Lowri E Cochlin
- Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Simon Nagel
- Nuffield Department of Clinical Medicine, University of Oxford
- Department of Neurology, University of Heidelberg, Germany
| | - Nicola R Sibson
- CRUK-MRC Gray Institute for Radiation Oncology and Biology, University of Oxford
| | - George K Radda
- Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford
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Abstract
The diabetic heart becomes metabolically remodelled as a consequence of exposure to abnormal circulating substrates and hormones. Fatty acid uptake and metabolism are increased in the type 2 diabetic heart, resulting in accumulation of intracellular lipid intermediates and an increased contribution of fatty acids towards energy generation. Cardiac glucose uptake and oxidation are decreased, predominantly due to increased fatty acid metabolism, which suppresses glucose utilisation via the Randle cycle. These metabolic changes decrease cardiac efficiency and energetics in both humans and animal models of diabetes. Diabetic hearts have decreased recovery following ischemia, indicating a reduced tolerance to oxygen-limited conditions. There is evidence that diabetic hearts have a compromised hypoxia signalling pathway, as hypoxia-inducible factor (HIF) and downstream signalling from HIF are reduced following ischemia. Failure to activate HIF under oxygen-limited conditions results in less angiogenesis, and an inability to upregulate glycolytic ATP generation. Given that glycolysis is already suppressed in the diabetic heart under normoxic conditions, the inability to upregulate glycolysis in response to hypoxia may have deleterious effects on ATP production. Thus, impaired HIF signalling may contribute to metabolic and energetic abnormalities, and impaired collateral vessel development following myocardial infarction in the type 2 diabetic heart.
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Affiliation(s)
- Lisa C Heather
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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O'Flaherty L, Adam J, Heather LC, Zhdanov AV, Chung YL, Miranda MX, Croft J, Olpin S, Clarke K, Pugh CW, Griffiths J, Papkovsky D, Ashrafian H, Ratcliffe PJ, Pollard PJ. Dysregulation of hypoxia pathways in fumarate hydratase-deficient cells is independent of defective mitochondrial metabolism. Hum Mol Genet 2010; 19:3844-51. [PMID: 20660115 PMCID: PMC2935862 DOI: 10.1093/hmg/ddq305] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 07/13/2010] [Indexed: 12/26/2022] Open
Abstract
Mutations in the gene encoding the Krebs cycle enzyme fumarate hydratase (FH) predispose to hereditary leiomyomatosis and renal cell cancer in affected individuals. FH-associated neoplasia is characterized by defective mitochondrial function and by upregulation of transcriptional pathways mediated by hypoxia-inducible factor (HIF), although whether and by what means these processes are linked has been disputed. We analysed the HIF pathway in Fh1-/- mouse embryonic fibroblasts (MEFs), in FH-defective neoplastic tissues and in Fh1-/- MEFs re-expressing either wild-type or an extra-mitochondrial restricted form of FH. These experiments demonstrated that upregulation of HIF-1alpha occurs as a direct consequence of FH inactivation. Fh1-/- cells accumulated intracellular fumarate and manifested severe impairment of HIF prolyl but not asparaginyl hydroxylation which was corrected by provision of exogenous 2-oxoglutarate (2-OG). Re-expression of the extra-mitochondrial form of FH in Fh1-/- cells was sufficient to reduce intracellular fumarate and to correct dysregulation of the HIF pathway completely, even in cells that remained profoundly defective in mitochondrial energy metabolism. The findings indicate that upregulation of HIF-1alpha arises from competitive inhibition of the 2-OG-dependent HIF hydroxylases by fumarate and not from disruption of mitochondrial energy metabolism.
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Affiliation(s)
- Linda O'Flaherty
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Julie Adam
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Lisa C. Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3QX, UK
| | - Alexander V. Zhdanov
- Department of Biochemistry, University College Cork, Cavanagh Pharmacy Building, 1.28 College Road, Cork, Ireland
| | - Yuen-Li Chung
- CRUK and ESPRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden Hospital, Sutton, Surrey SM2 5PT, UK
| | - Melroy X. Miranda
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Joanne Croft
- The Sheffield Children's NHS Trust, Immuno Bank, Sheffield S10 2TH, UK
| | - Simon Olpin
- The Sheffield Children's NHS Trust, Immuno Bank, Sheffield S10 2TH, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3QX, UK
| | - Christopher W. Pugh
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - John Griffiths
- Cancer Research UK Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK and
| | - Dmitri Papkovsky
- Department of Biochemistry, University College Cork, Cavanagh Pharmacy Building, 1.28 College Road, Cork, Ireland
| | - Houman Ashrafian
- Department of Cardiovascular Medicine, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Headley Way, Headington, Oxford OX3 9DU, UK
| | - Peter J. Ratcliffe
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Patrick J. Pollard
- Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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