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Aromolaran KA, Corbin A, Aromolaran AS. Obesity Arrhythmias: Role of IL-6 Trans-Signaling. Int J Mol Sci 2024; 25:8407. [PMID: 39125976 PMCID: PMC11313575 DOI: 10.3390/ijms25158407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2024] [Revised: 07/24/2024] [Accepted: 07/29/2024] [Indexed: 08/12/2024] Open
Abstract
Obesity is a chronic disease that is rapidly increasing in prevalence and affects more than 600 million adults worldwide, and this figure is estimated to increase by at least double by 2030. In the United States, more than one-third of the adult population is either overweight or obese. The global obesity epidemic is a major risk factor for the development of life-threatening arrhythmias occurring in patients with long QT, particularly in conditions where multiple heart-rate-corrected QT-interval-prolonging mechanisms are simultaneously present. In obesity, excess dietary fat in adipose tissue stimulates the release of immunomodulatory cytokines such as interleukin (IL)-6, leading to a state of chronic inflammation in patients. Over the last decade, increasing evidence has been found to support IL-6 signaling as a powerful predictor of the severity of heart diseases and increased risk for ventricular arrhythmias. IL-6's pro-inflammatory effects are mediated via trans-signaling and may represent a novel arrhythmogenic risk factor in obese hearts. The first selective inhibitor of IL-6 trans-signaling, olamkicept, has shown encouraging results in phase II clinical studies for inflammatory bowel disease. Nevertheless, the connection between IL-6 trans-signaling and obesity-linked ventricular arrhythmias remains unexplored. Therefore, understanding how IL-6 trans-signaling elicits a cellular pro-arrhythmic phenotype and its use as an anti-arrhythmic target in a model of obesity remain unmet clinical needs.
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Affiliation(s)
- Kelly A. Aromolaran
- Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI), University of Utah School of Medicine, Salt Lake City, UT 84112, USA; (K.A.A.); (A.C.)
| | - Andrea Corbin
- Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI), University of Utah School of Medicine, Salt Lake City, UT 84112, USA; (K.A.A.); (A.C.)
- Department of Biomedical Engineering, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Ademuyiwa S. Aromolaran
- Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI), University of Utah School of Medicine, Salt Lake City, UT 84112, USA; (K.A.A.); (A.C.)
- Department of Biomedical Engineering, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- Department of Surgery, Division of Cardiothoracic Surgery, Nutrition & Integrative Physiology, Biochemistry & Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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2
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Gone GB, Go G, Nam G, Jeong W, Kim H, Lee S, Chung SJ. Exploring the Anti-Diabetic Potential of Quercetagitrin through Dual Inhibition of PTPN6 and PTPN9. Nutrients 2024; 16:647. [PMID: 38474775 DOI: 10.3390/nu16050647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/19/2024] [Accepted: 02/23/2024] [Indexed: 03/14/2024] Open
Abstract
Protein tyrosine phosphatases (PTPs) are pivotal contributors to the development of type 2 diabetes (T2DM). Hence, directing interventions towards PTPs emerges as a valuable therapeutic approach for managing type 2 diabetes. In particular, PTPN6 and PTPN9 are targets for anti-diabetic effects. Through high-throughput drug screening, quercetagitrin (QG) was recognized as a dual-target inhibitor of PTPN6 and PTPN9. We observed that QG suppressed the catalytic activity of PTPN6 (IC50 = 1 μM) and PTPN9 (IC50 = 1.7 μM) in vitro and enhanced glucose uptake by mature C2C12 myoblasts. Additionally, QG increased the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and insulin-dependent phosphorylation of Akt in mature C2C12 myoblasts. It further promoted the phosphorylation of Akt in the presence of palmitic acid, suggesting the attenuation of insulin resistance. In summary, our results indicate QG's role as a potent inhibitor targeting both PTPN6 and PTPN9, showcasing its potential as a promising treatment avenue for T2DM.
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Affiliation(s)
- Geetanjali B Gone
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Geonhui Go
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Gibeom Nam
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Woojoo Jeong
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Hyemin Kim
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Soah Lee
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Sang J Chung
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
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3
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Załęska-Kocięcka M, Wojdyńska Z, Kalisz M, Litwiniuk A, Mączewski M, Leszek P, Paterek A. Epicardial fat and ventricular arrhythmias. Heart Rhythm 2024; 21:206-212. [PMID: 37972673 DOI: 10.1016/j.hrthm.2023.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 11/03/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023]
Abstract
The arrhythmogenic role of epicardial adipose tissue (EAT) in atrial arrhythmias is well established, but its effect on ventricular arrhythmias has been significantly less investigated. Since ventricular arrhythmias are thought to cause 75%-80% of cases of sudden cardiac death, this is not a trivial issue. We provide an overview of clinical data as well as experimental and molecular data linking EAT to ventricular arrhythmias, attempting to dissect possible mechanisms and indicate future directions of research and possible clinical implications. However, despite a wealth of data indicating the role of epicardial and intramyocardial fat in the induction and propagation of ventricular arrhythmias, unfortunately there is currently no direct evidence that indeed EAT triggers arrhythmia or can be a target for antiarrhythmic strategies.
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Affiliation(s)
- Marta Załęska-Kocięcka
- Heart Failure and Transplantology Department, Mechanical Circulatory Support and Transplant Department, National Institute of Cardiology, Warsaw, Poland
| | - Zuzanna Wojdyńska
- Heart Failure and Transplantology Department, Mechanical Circulatory Support and Transplant Department, National Institute of Cardiology, Warsaw, Poland
| | - Małgorzata Kalisz
- Department of Clinical Neuroendocrinology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Anna Litwiniuk
- Department of Clinical Neuroendocrinology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Michał Mączewski
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Przemysław Leszek
- Heart Failure and Transplantology Department, Mechanical Circulatory Support and Transplant Department, National Institute of Cardiology, Warsaw, Poland
| | - Aleksandra Paterek
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Warsaw, Poland.
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4
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Borlaug BA, Jensen MD, Kitzman DW, Lam CSP, Obokata M, Rider OJ. Obesity and heart failure with preserved ejection fraction: new insights and pathophysiological targets. Cardiovasc Res 2023; 118:3434-3450. [PMID: 35880317 PMCID: PMC10202444 DOI: 10.1093/cvr/cvac120] [Citation(s) in RCA: 77] [Impact Index Per Article: 77.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/28/2022] [Accepted: 07/01/2022] [Indexed: 02/07/2023] Open
Abstract
Obesity and heart failure with preserved ejection fraction (HFpEF) represent two intermingling epidemics driving perhaps the greatest unmet health problem in cardiovascular medicine in the 21st century. Many patients with HFpEF are either overweight or obese, and recent data have shown that increased body fat and its attendant metabolic sequelae have widespread, protean effects systemically and on the cardiovascular system leading to symptomatic HFpEF. The paucity of effective therapies in HFpEF underscores the importance of understanding the distinct pathophysiological mechanisms of obese HFpEF to develop novel therapies. In this review, we summarize the current understanding of the cardiovascular and non-cardiovascular features of the obese phenotype of HFpEF, how increased adiposity might pathophysiologically contribute to the phenotype, and how these processes might be targeted therapeutically.
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Affiliation(s)
- Barry A Borlaug
- Department of Cardiovascular Diseases, Mayo Clinic Rochester, 200 First Street SW, Rochester, MN 55905, USA
| | | | - Dalane W Kitzman
- Department of Internal Medicine, Section on Cardiology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | | | - Masaru Obokata
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Oliver J Rider
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK
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5
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Aromolaran KA, Do J, Bernardi J, Aromolaran AS. mTOR Modulation of IKr through hERG1b-Dependent Mechanisms in Lipotoxic Heart. Int J Mol Sci 2022; 23:8061. [PMID: 35897638 PMCID: PMC9329916 DOI: 10.3390/ijms23158061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/17/2022] [Accepted: 07/20/2022] [Indexed: 12/04/2022] Open
Abstract
In the atria, the rapid delayed rectifier channel (IKr) is a critical contributor to repolarization. In lipotoxic atria, increased activity of the serine/threonine mammalian target of rapamycin (mTOR) may remodel IKr and predispose patients to arrhythmias. To investigate whether mTOR produced defects in IKr channel function (protein expression and gating mechanisms), electrophysiology and biochemical assays in HEK293 cells stably expressing hERG1a/1b, and adult guinea pig atrial myocytes were used. Feeding with the saturated fatty acid palmitic acid high-fat diet (HFD) was used to induce lipotoxicity. Lipotoxicity-challenged HEK293 cells displayed an increased density of hERG1a/1b currents due to a targeted and significant increase in hERG1b protein expression. Furthermore, lipotoxicity significantly slowed the hERG1a/1b inactivation kinetics, while the activation and deactivation remained essentially unchanged. mTOR complex 1 (mTORC1) inhibition with rapamycin (RAP) reversed the increase in hERG1a/1b density and inactivation. Compared to lipotoxic myocytes, RAP-treated cells displayed action potential durations (APDs) and IKr densities similar to those of controls. HFD feeding triggered arrhythmogenic changes (increased the IKr density and shortened the APD) in the atria, but this was not observed in low-fat-fed controls. The data are the first to show the modulation of IKr by mTORC1, possibly through the remodeling of hERG1b, in lipotoxic atrial myocytes. These results offer mechanistic insights with implications for targeted therapeutic options for the therapy of acquired supraventricular arrhythmias in obesity and associated pathologies.
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Affiliation(s)
- Kelly A. Aromolaran
- Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI), University of Utah School of Medicine, Salt Lake City, UT 84112, USA;
| | - Jenny Do
- Masonic Medical Research Institute, Utica, NY 13501, USA; (J.D.); (J.B.)
| | - Joyce Bernardi
- Masonic Medical Research Institute, Utica, NY 13501, USA; (J.D.); (J.B.)
| | - Ademuyiwa S. Aromolaran
- Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI), University of Utah School of Medicine, Salt Lake City, UT 84112, USA;
- Masonic Medical Research Institute, Utica, NY 13501, USA; (J.D.); (J.B.)
- Department of Surgery, Division of Cardiothoracic Surgery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
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6
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Kim J, Son J, Ahn D, Nam G, Zhao X, Park H, Jeong W, Chung SJ. Structure-Activity Relationship of Synthetic Ginkgolic Acid Analogs for Treating Type 2 Diabetes by PTPN9 Inhibition. Int J Mol Sci 2022; 23:ijms23073927. [PMID: 35409287 PMCID: PMC8999917 DOI: 10.3390/ijms23073927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 02/01/2023] Open
Abstract
Ginkgolic acid (C13:0) (GA), isolated from Ginkgo biloba, is a potential therapeutic agent for type 2 diabetes. A series of GA analogs were designed and synthesized for the evaluation of their structure–activity relationship with respect to their antidiabetic effects. Unlike GA, the synthetic analog 1e exhibited improved inhibitory activity against PTPN9 and significantly stimulated glucose uptake via AMPK phosphorylation in differentiated 3T3-L1 adipocytes and C2C12 myotubes; it also induced insulin-dependent AKT activation in C2C12 myotubes in a concentration-dependent manner. Docking simulation results showed that 1e had a better binding affinity through a unique hydrophobic interaction with a PTPN9 hydrophobic groove. Moreover, 1e ameliorated palmitate-induced insulin resistance in C2C12 cells. This study showed that 1e increases glucose uptake and suppresses palmitate-induced insulin resistance in C2C12 myotubes via PTPN9 inhibition; thus, it is a promising therapeutic candidate for treating type 2 diabetes.
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Affiliation(s)
- Jinsoo Kim
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (J.K.); (D.A.); (G.N.); (X.Z.)
| | - Jinyoung Son
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Korea; (J.S.); (H.P.); (W.J.)
| | - Dohee Ahn
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (J.K.); (D.A.); (G.N.); (X.Z.)
| | - Gibeom Nam
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (J.K.); (D.A.); (G.N.); (X.Z.)
| | - Xiaodi Zhao
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (J.K.); (D.A.); (G.N.); (X.Z.)
| | - Hyuna Park
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Korea; (J.S.); (H.P.); (W.J.)
| | - Woojoo Jeong
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Korea; (J.S.); (H.P.); (W.J.)
| | - Sang J. Chung
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (J.K.); (D.A.); (G.N.); (X.Z.)
- Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Korea; (J.S.); (H.P.); (W.J.)
- Correspondence:
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Patel KHK, Hwang T, Se Liebers C, Ng FS. Epicardial adipose tissue as a mediator of cardiac arrhythmias. Am J Physiol Heart Circ Physiol 2022; 322:H129-H144. [PMID: 34890279 PMCID: PMC8742735 DOI: 10.1152/ajpheart.00565.2021] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Obesity is associated with higher risks of cardiac arrhythmias. Although this may be partly explained by concurrent cardiometabolic ill-health, growing evidence suggests that increasing adiposity independently confers risk for arrhythmias. Among fat depots, epicardial adipose tissue (EAT) exhibits a proinflammatory secretome and, given the lack of fascial separation, has been implicated as a transducer of inflammation to the underlying myocardium. The present review explores the mechanisms underpinning adverse electrophysiological remodeling as a consequence of EAT accumulation and the consequent inflammation. We first describe the physiological and pathophysiological function of EAT and its unique secretome and subsequently discuss the evidence for ionic channel and connexin expression modulation as well as fibrotic remodeling induced by cytokines and free fatty acids that are secreted by EAT. Finally, we highlight how weight reduction and regression of EAT volume may cause reverse remodeling to ameliorate arrhythmic risk.
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Affiliation(s)
| | - Taesoon Hwang
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Curtis Se Liebers
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Fu Siong Ng
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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8
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Macrophage-Dependent Interleukin-6-Production and Inhibition of IK Contributes to Acquired QT Prolongation in Lipotoxic Guinea Pig Heart. Int J Mol Sci 2021; 22:ijms222011249. [PMID: 34681909 PMCID: PMC8537919 DOI: 10.3390/ijms222011249] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/08/2021] [Accepted: 10/16/2021] [Indexed: 11/17/2022] Open
Abstract
In the heart, the delayed rectifier K current, IK, composed of the rapid (IKr) and slow (IKs) components contributes prominently to normal cardiac repolarization. In lipotoxicity, chronic elevation of pro-inflammatory cytokines may remodel IK, elevating the risk for ventricular arrythmias and sudden cardiac death. We investigated whether and how the pro-inflammatory interleukin-6 altered IK in the heart, using electrophysiology to evaluate changes in IK in adult guinea pig ventricular myocytes. We found that palmitic acid (a potent inducer of lipotoxicity), induced a rapid (~24 h) and significant increase in IL-6 in RAW264.7 cells. PA-diet fed guinea pigs displayed a severely prolonged QT interval when compared to low-fat diet fed controls. Exposure to isoproterenol induced torsade de pointes, and ventricular fibrillation in lipotoxic guinea pigs. Pre-exposure to IL-6 with the soluble IL-6 receptor produced a profound depression of IKr and IKs densities, prolonged action potential duration, and impaired mitochondrial ATP production. Only with the inhibition of IKr did a proarrhythmic phenotype of IKs depression emerge, manifested as a further prolongation of action potential duration and QT interval. Our data offer unique mechanistic insights with implications for pathological QT interval in patients and vulnerability to fatal arrhythmias.
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Neurological Disorders and Risk of Arrhythmia. Int J Mol Sci 2020; 22:ijms22010188. [PMID: 33375447 PMCID: PMC7795827 DOI: 10.3390/ijms22010188] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/19/2020] [Accepted: 12/24/2020] [Indexed: 01/08/2023] Open
Abstract
Neurological disorders including depression, anxiety, post-traumatic stress disorder (PTSD), schizophrenia, autism and epilepsy are associated with an increased incidence of cardiovascular disorders and susceptibility to heart failure. The underlying molecular mechanisms that link neurological disorders and adverse cardiac function are poorly understood. Further, a lack of progress is likely due to a paucity of studies that investigate the relationship between neurological disorders and cardiac electrical activity in health and disease. Therefore, there is an important need to understand the spatiotemporal behavior of neurocardiac mechanisms. This can be advanced through the identification and validation of neurological and cardiac signaling pathways that may be adversely regulated. In this review we highlight how dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system (ANS) activity and inflammation, predispose to psychiatric disorders and cardiac dysfunction. Moreover, antipsychotic and antidepressant medications increase the risk for adverse cardiac events, mostly through the block of the human ether-a-go-go-related gene (hERG), which plays a critical role in cardiac repolarization. Therefore, understanding how neurological disorders lead to adverse cardiac ion channel remodeling is likely to have significant implications for the development of effective therapeutic interventions and helps improve the rational development of targeted therapeutics with significant clinical implications.
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Soppert J, Lehrke M, Marx N, Jankowski J, Noels H. Lipoproteins and lipids in cardiovascular disease: from mechanistic insights to therapeutic targeting. Adv Drug Deliv Rev 2020; 159:4-33. [PMID: 32730849 DOI: 10.1016/j.addr.2020.07.019] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 07/20/2020] [Accepted: 07/22/2020] [Indexed: 12/12/2022]
Abstract
With cardiovascular disease being the leading cause of morbidity and mortality worldwide, effective and cost-efficient therapies to reduce cardiovascular risk are highly needed. Lipids and lipoprotein particles crucially contribute to atherosclerosis as underlying pathology of cardiovascular disease and influence inflammatory processes as well as function of leukocytes, vascular and cardiac cells, thereby impacting on vessels and heart. Statins form the first-line therapy with the aim to block cholesterol synthesis, but additional lipid-lowering drugs are sometimes needed to achieve low-density lipoprotein (LDL) cholesterol target values. Furthermore, beyond LDL cholesterol, also other lipid mediators contribute to cardiovascular risk. This review comprehensively discusses low- and high-density lipoprotein cholesterol, lipoprotein (a), triglycerides as well as fatty acids and derivatives in the context of cardiovascular disease, providing mechanistic insights into their role in pathological processes impacting on cardiovascular disease. Also, an overview of applied as well as emerging therapeutic strategies to reduce lipid-induced cardiovascular burden is provided.
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Affiliation(s)
- Josefin Soppert
- Institute for Molecular Cardiovascular Research (IMCAR), University Hospital Aachen, Aachen, Germany
| | - Michael Lehrke
- Medical Clinic I, University Hospital Aachen, Aachen, Germany
| | - Nikolaus Marx
- Medical Clinic I, University Hospital Aachen, Aachen, Germany
| | - Joachim Jankowski
- Institute for Molecular Cardiovascular Research (IMCAR), University Hospital Aachen, Aachen, Germany; Department of Pathology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht University, the Netherlands
| | - Heidi Noels
- Institute for Molecular Cardiovascular Research (IMCAR), University Hospital Aachen, Aachen, Germany; Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, the Netherlands.
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Gullberg GT, Shrestha UM, Seo Y. Dynamic cardiac PET imaging: Technological improvements advancing future cardiac health. J Nucl Cardiol 2019; 26:1292-1297. [PMID: 29388118 PMCID: PMC6068005 DOI: 10.1007/s12350-018-1201-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Grant T Gullberg
- Department of Radiology and Biomedical Imaging, University of California, 185 Berry St., Ste 350, San Francisco, CA, 94143-0946, USA.
| | - Uttam M Shrestha
- Department of Radiology and Biomedical Imaging, University of California, 185 Berry St., Ste 350, San Francisco, CA, 94143-0946, USA
| | - Youngho Seo
- Department of Radiology and Biomedical Imaging, University of California, 185 Berry St., Ste 350, San Francisco, CA, 94143-0946, USA
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12
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Murphy JT, Liu H, Ma X, Shaver A, Egan BM, Oh C, Boyko A, Mazer T, Ang S, Khopkar R, Javaheri A, Kumar S, Jiang X, Ory D, Mani K, Matkovich SJ, Kornfeld K, Diwan A. Simple nutrients bypass the requirement for HLH-30 in coupling lysosomal nutrient sensing to survival. PLoS Biol 2019; 17:e3000245. [PMID: 31086360 PMCID: PMC6516633 DOI: 10.1371/journal.pbio.3000245] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Accepted: 04/10/2019] [Indexed: 12/11/2022] Open
Abstract
Lysosomes are ubiquitous acidified organelles that degrade intracellular and extracellular material trafficked via multiple pathways. Lysosomes also sense cellular nutrient levels to regulate target of rapamycin (TOR) kinase, a signaling enzyme that drives growth and suppresses activity of the MiT/TFE family of transcription factors that control biogenesis of lysosomes. In this study, we subjected worms lacking basic helix–loop–helix transcription factor 30 (hlh-30), the Caenorhabditis elegans MiT/TFE ortholog, to starvation followed by refeeding to understand how this pathway regulates survival with variable nutrient supply. Loss of HLH-30 markedly impaired survival in starved larval worms and recovery upon refeeding bacteria. Remarkably, provision of simple nutrients in a completely defined medium (C. elegans maintenance medium [CeMM]), specifically glucose and linoleic acid, restored lysosomal acidification, TOR activation, and survival with refeeding despite the absence of HLH-30. Worms deficient in lysosomal lipase 2 (lipl-2), a lysosomal enzyme that is transcriptionally up-regulated in starvation in an HLH-30–dependent manner, also demonstrated increased mortality with starvation–refeeding that was partially rescued with glucose, suggesting a critical role for LIPL-2 in lipid metabolism under starvation. CeMM induced transcription of vacuolar proton pump subunits in hlh-30 mutant worms, and knockdown of vacuolar H+-ATPase 12 (vha-12) and its upstream regulator, nuclear hormone receptor 31 (nhr-31), abolished the rescue with CeMM. Loss of Ras-related GTP binding protein C homolog 1 RAGC-1, the ortholog for mammalian RagC/D GTPases, conferred starvation–refeeding lethality, and RAGC-1 overexpression was sufficient to rescue starved hlh-30 mutant worms, demonstrating a critical need for TOR activation with refeeding. These results show that HLH-30 activation is critical for sustaining survival during starvation–refeeding stress via regulating TOR. Glucose and linoleic acid bypass the requirement for HLH-30 in coupling lysosome nutrient sensing to survival. Lysosomes play a central role in coupling the nutrient state of the cell to growth and survival decisions. This study uncovers a critical role for HLH-30, the nematode ortholog of the mammalian MiT/TFE family of master regulators of lysosome biogenesis, in survival under starvation and refeeding conditions. Refeeding simple nutrients bypasses the requirement for HLH-30 to permit survival.
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Affiliation(s)
- John T. Murphy
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Haiyan Liu
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- John Cochran VA Medical Center, St. Louis, Missouri, United States of America
| | - Xiucui Ma
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- John Cochran VA Medical Center, St. Louis, Missouri, United States of America
| | - Alex Shaver
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Brian M. Egan
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Clara Oh
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Alexander Boyko
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Travis Mazer
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Samuel Ang
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Rohan Khopkar
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Ali Javaheri
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Sandeep Kumar
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Xuntian Jiang
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Daniel Ory
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kartik Mani
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- John Cochran VA Medical Center, St. Louis, Missouri, United States of America
| | - Scot J. Matkovich
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kerry Kornfeld
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Abhinav Diwan
- Center for Cardiovascular Research and Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- John Cochran VA Medical Center, St. Louis, Missouri, United States of America
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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13
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Jensen CF, Bartels ED, Braunstein TH, Nielsen LB, Holstein‐Rathlou N, Axelsen LN, Nielsen MS. Acute intramyocardial lipid accumulation in rats does not slow cardiac conduction per se. Physiol Rep 2019; 7:e14049. [PMID: 30968589 PMCID: PMC6456446 DOI: 10.14814/phy2.14049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 01/14/2023] Open
Abstract
Diabetic patients suffer from both cardiac lipid accumulation and an increased risk of arrhythmias and sudden cardiac death. This correlation suggests a link between diabetes induced cardiac steatosis and electrical abnormalities, however, the underlying mechanism remains unknown. We previously showed that cardiac conduction velocity slows in Zucker diabetic fatty rats and in fructose-fat fed rats, models that both exhibit prominent cardiac steatosis. The aim of this study was to investigate whether acute cardiac lipid accumulation reduces conduction velocity per se. Cardiac lipid accumulation was induced acutely by perfusing isolated rat hearts with palmitate-glucose buffer, or subacutely by fasting rats overnight. Subsequently, longitudinal cardiac conduction velocity was measured in right ventricular tissue strips, and intramyocardial triglyceride and lipid droplet content was determined by thin layer chromatography and BODIPY staining, respectively. Perfusion with palmitate-glucose buffer significantly increased intramyocardial triglyceride levels compared to perfusion with glucose (2.16 ± 0.17 (n = 10) vs. 0.92 ± 0.33 nmol/mg WW (n = 9), P < 0.01), but the number of lipid droplets was very low in both groups. Fasting of rats, however, resulted in both significantly elevated intramyocardial triglyceride levels compared to fed rats (3.27 ± 0.43 (n = 10) vs. 1.45 ± 0.24 nmol/mg WW (n = 10)), as well as a larger volume of lipid droplets (0.60 ± 0.13 (n = 10) vs. 0.21 ± 0.06% (n = 10), P < 0.05). There was no significant difference in longitudinal conduction velocity between palmitate-glucose perfused and control hearts (0.77 ± 0.025 (n = 10) vs. 0.75 m/sec ± 0.029 (n = 9)), or between fed and fasted rats (0.75 ± 0.042 m/sec (n = 10) vs. 0.79 ± 0.047 (n = 10)). In conclusion, intramyocardial lipid accumulation does not slow cardiac longitudinal conduction velocity per se. This is true for both increased intramyocardial triglyceride content, induced by palmitate-glucose perfusion, and increased intramyocardial triglyceride and lipid droplet content, generated by fasting.
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Affiliation(s)
- Christa F. Jensen
- Department of Biomedical SciencesFaculty of Health SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Emil D. Bartels
- Department of Clinical BiochemistryCopenhagen University Hospital RigshospitaletCopenhagenDenmark
| | - Thomas H. Braunstein
- Department of Biomedical SciencesFaculty of Health SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Lars B. Nielsen
- Department of Clinical BiochemistryCopenhagen University Hospital RigshospitaletCopenhagenDenmark
| | | | - Lene N. Axelsen
- Department of Biomedical SciencesFaculty of Health SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Morten Schak Nielsen
- Department of Biomedical SciencesFaculty of Health SciencesUniversity of CopenhagenCopenhagenDenmark
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14
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Wang W, Mellor RL, Nerbonne JM, Balke CW. Regional differences in the expression of tetrodotoxin-sensitive inward Ca 2+ and outward Cs +/K + currents in mouse and human ventricles. Channels (Austin) 2019; 13:72-87. [PMID: 30704344 PMCID: PMC6380286 DOI: 10.1080/19336950.2019.1568146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Tetrodotoxin (TTX) sensitive inward Ca2+ currents, ICa(TTX), have been identified in cardiac myocytes from several species, although it is unclear if ICa(TTX) is expressed in all cardiac cell types, and if ICa(TTX) reflects Ca2+ entry through the main, Nav1.5-encoded, cardiac Na+ (Nav) channels. To address these questions, recordings were obtained with 2 mm Ca2+ and 0 mm Na+ in the bath and 120 mm Cs+ in the pipettes from myocytes isolated from adult mouse interventricular septum (IVS), left ventricular (LV) endocardium, apex, and epicardium and from human LV endocardium and epicardium. On membrane depolarizations from a holding potential of −100 mV, ICa(TTX) was identified in mouse IVS and LV endocardial myocytes and in human LV endocardial myocytes, whereas only TTX-sensitive outward Cs+/K+ currents were observed in mouse LV apex and epicardial myocytes and human LV epicardial myocytes. The inward Ca2+, but not the outward Cs+/K+, currents were blocked by mm concentrations of MTSEA, a selective blocker of cardiac Nav1.5-encoded Na+ channels. In addition, in Nav1.5-expressing tsA-201 cells, ICa(TTX) was observed in 3 (of 20) cells, and TTX-sensitive outward Cs+/K+ currents were observed in the other (17) cells. The time- and voltage-dependent properties of the TTX-sensitive inward Ca2+ and outward Cs+/K+ currents recorded in Nav1.5-expressing tsA-201 were indistinguishable from native currents in mouse and human cardiac myocytes. Overall, the results presented here suggest marked regional, cell type-specific, differences in the relative ion selectivity, and likely the molecular architecture, of native SCN5A-/Scn5a- (Nav1.5-) encoded cardiac Na+ channels in mouse and human ventricles.
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Affiliation(s)
- Wei Wang
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA
| | - Rebecca L Mellor
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA
| | - Jeanne M Nerbonne
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA.,b John Cochran Veterans Administration Medical Center , St. Louis , MO , USA
| | - C William Balke
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA.,b John Cochran Veterans Administration Medical Center , St. Louis , MO , USA
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15
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Alí A, Boutjdir M, Aromolaran AS. Cardiolipotoxicity, Inflammation, and Arrhythmias: Role for Interleukin-6 Molecular Mechanisms. Front Physiol 2019; 9:1866. [PMID: 30666212 PMCID: PMC6330352 DOI: 10.3389/fphys.2018.01866] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
Abstract
Fatty acid infiltration of the myocardium, acquired in metabolic disorders (obesity, type-2 diabetes, insulin resistance, and hyperglycemia) is critically associated with the development of lipotoxic cardiomyopathy. According to a recent Presidential Advisory from the American Heart Association published in 2017, the current average dietary intake of saturated free-fatty acid (SFFA) in the US is 11–12%, which is significantly above the recommended <10%. Increased levels of circulating SFFAs (or lipotoxicity) may represent an unappreciated link that underlies increased vulnerability to cardiac dysfunction. Thus, an important objective is to identify novel targets that will inform pharmacological and genetic interventions for cardiomyopathies acquired through excessive consumption of diets rich in SFFAs. However, the molecular mechanisms involved are poorly understood. The increasing epidemic of metabolic disorders strongly implies an undeniable and critical need to further investigate SFFA mechanisms. A rapidly emerging and promising target for modulation by lipotoxicity is cytokine secretion and activation of pro-inflammatory signaling pathways. This objective can be advanced through fundamental mechanisms of cardiac electrical remodeling. In this review, we discuss cardiac ion channel modulation by SFFAs. We further highlight the contribution of downstream signaling pathways involving toll-like receptors and pathological increases in pro-inflammatory cytokines. Our expectation is that if we understand pathological remodeling of major cardiac ion channels from a perspective of lipotoxicity and inflammation, we may be able to develop safer and more effective therapies that will be beneficial to patients.
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Affiliation(s)
- Alessandra Alí
- Cardiovascular Research Program, VA New York Harbor Healthcare System, Brooklyn, NY, United States.,Department of Medicine, State University of New York Downstate Medical Center, Brooklyn, NY, United States.,Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY, United States.,Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn, NY, United States.,Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, Brooklyn, NY, United States.,Department of Medicine, State University of New York Downstate Medical Center, Brooklyn, NY, United States.,Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY, United States.,Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn, NY, United States.,Department of Medicine, New York University School of Medicine, New York, NY, United States
| | - Ademuyiwa S Aromolaran
- Cardiovascular Research Program, VA New York Harbor Healthcare System, Brooklyn, NY, United States.,Department of Medicine, State University of New York Downstate Medical Center, Brooklyn, NY, United States.,Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY, United States.,Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn, NY, United States
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16
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Carpentier AC. Abnormal Myocardial Dietary Fatty Acid Metabolism and Diabetic Cardiomyopathy. Can J Cardiol 2018; 34:605-614. [PMID: 29627307 DOI: 10.1016/j.cjca.2017.12.029] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/08/2017] [Accepted: 12/19/2017] [Indexed: 12/13/2022] Open
Abstract
Patients with diabetes are at very high risk of hospitalization and death from heart failure. Increased prevalence of coronary heart disease, hypertension, autonomic neuropathy, and kidney failure all play a role in this increased risk. However, cardiac metabolic abnormalities are now recognized to play a role in this increased risk. Increased reliance on fatty acids to produce energy might predispose the diabetic heart to oxidative stress and ischemic damage. Intramyocellular accumulation of toxic lipid metabolites leads to a number of cellular abnormalities that might also contribute to cardiac remodelling and cardiac dysfunction. However, fatty acid availability from circulation and from intracellular lipid droplets to fuel the heart is critical to maintain its function. Fatty acids delivery to the heart is very complex and includes plasma nonesterified fatty acid flux as well as triglyceride-rich lipoprotein-mediated transport. Although many studies have shown a cross-sectional association between enhanced fatty acid delivery to the heart and reduction in left ventricular function in subjects with prediabetes and diabetes, these mechanisms change very rapidly during type 2 diabetes treatment. The present review focuses on the role of fatty acids in cardiac function, with particular emphasis on the possible role of early abnormalities of dietary fatty acid metabolism in the development of diabetic cardiomyopathy.
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Affiliation(s)
- André C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Québec, Canada.
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17
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Boardman NT, Hafstad AD, Lund J, Rossvoll L, Aasum E. Exercise of obese mice induces cardioprotection and oxygen sparing in hearts exposed to high-fat load. Am J Physiol Heart Circ Physiol 2017; 313:H1054-H1062. [DOI: 10.1152/ajpheart.00382.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 08/03/2017] [Accepted: 08/08/2017] [Indexed: 02/03/2023]
Abstract
Exercise training is a potent therapeutic approach in obesity and diabetes that exerts protective effects against the development of diabetic cardiomyopathy and ischemic injury. Acute increases in circulating fatty acids (FAs) during an ischemic insult can challenge the heart, since high FA load is considered to have adverse cardiac effects. In the present study, we tested the hypothesis that exercise-induced cardiac effects in diet-induced obese mice are abrogated by an acute high FA load. Diet-induced obese mice were fed a high-fat diet (HFD) for 20 wk. They were exercised using moderate- and/or high-intensity exercise training (MIT and HIT, respectively) for 10 or 3 wk, and isolated perfused hearts from these mice were exposed to a high FA load. Sedentary HFD mice served as controls. Ventricular function and myocardial O2 consumption were assessed after 10 wk of HIT and MIT, and postischemic functional recovery and infarct size were examined after 3 wk of HIT. In addition to improving aerobic capacity and reducing obesity and insulin resistance, long-term exercise ameliorated the development of diet-induced cardiac dysfunction. This was associated with improved mechanical efficiency because of reduced myocardial oxygen consumption. Although to a lesser extent, 3-wk HIT also increased aerobic capacity and decreased obesity and insulin resistance. HIT also improved postischemic functional recovery and reduced infarct size. Event upon the exposure to a high FA load, short-term exercise induced an oxygen-sparing effect. This study therefore shows that exercise-induced cardioprotective effects are present under hyperlipidemic conditions and highlights the important role of myocardial energetics during ischemic stress. NEW & NOTEWORTHY The exercise-induced cardioprotective effects in obese hearts are present under hyperlipidemic conditions, comparable to circulating levels of FA occurring with an ischemic insult. Myocardial oxygen sparing is associated with this effect, despite the general notion that high fat can decrease cardiac efficiency. This highlights the role of myocardial energetics during ischemic stress.
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Affiliation(s)
- Neoma T. Boardman
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Anne D. Hafstad
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Jim Lund
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Line Rossvoll
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Ellen Aasum
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
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18
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Aromolaran AS, Boutjdir M. Cardiac Ion Channel Regulation in Obesity and the Metabolic Syndrome: Relevance to Long QT Syndrome and Atrial Fibrillation. Front Physiol 2017; 8:431. [PMID: 28680407 PMCID: PMC5479057 DOI: 10.3389/fphys.2017.00431] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 06/06/2017] [Indexed: 01/03/2023] Open
Abstract
Obesity and its associated metabolic dysregulation leading to metabolic syndrome is an epidemic that poses a significant public health problem. More than one-third of the world population is overweight or obese leading to enhanced risk of cardiovascular disease (CVD) incidence and mortality. Obesity predisposes to atrial fibrillation, ventricular, and supraventricular arrhythmias; conditions that are underlain by dysfunction in electrical activity of the heart. To date, current therapeutic options for cardiomyopathy of obesity are limited, suggesting that there is considerable room for development of therapeutic interventions with novel mechanisms of action that will help normalize rhythm in obese patients. Emerging candidates for modulation by obesity are cardiac ion channels and Ca handling proteins. However, the underlying molecular mechanisms of the impact of obesity on these channels/Ca handling proteins remain incompletely understood. Obesity is marked by accumulation of adipose tissue associated with a variety of adverse adaptations including dyslipidemia (or abnormal levels of serum free fatty acids), increased secretion of pro-inflammatory cytokines, fibrosis, hyperglycemia, and insulin resistance, that will cause electrical remodeling and thus predispose to arrhythmias. Further, adipose tissue is also associated with the accumulation of subcutaneous and visceral fat, which are marked by distinct signaling mechanisms. Thus, there may also be functional differences in the outcome of regional distribution of fat deposits on ion channel/Ca handling proteins expression. Evaluating alterations in their functional expression in obesity will lead to progress in the knowledge about the mechanisms responsible for obesity-related arrhythmias. These advances are likely to reveal new targets for pharmacological modulation. The objective of this article is to review cardiac ion channel/Ca handling proteins remodeling that predispose to arrhythmias. Understanding how obesity and related mechanisms lead to cardiac electrical remodeling is likely to have a significant medical and economic impact.
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Affiliation(s)
- Ademuyiwa S Aromolaran
- Cardiovascular Research Program, VA New York Harbor Healthcare SystemBrooklyn, NY, United States.,Departments of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Medical CenterBrooklyn, NY, United States
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare SystemBrooklyn, NY, United States.,Departments of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Medical CenterBrooklyn, NY, United States.,Department of Medicine, New York University School of MedicineNew York, NY, United States
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19
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Li S, Zhang L, Ni R, Cao T, Zheng D, Xiong S, Greer PA, Fan GC, Peng T. Disruption of calpain reduces lipotoxicity-induced cardiac injury by preventing endoplasmic reticulum stress. Biochim Biophys Acta Mol Basis Dis 2016; 1862:2023-2033. [PMID: 27523632 DOI: 10.1016/j.bbadis.2016.08.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/15/2016] [Accepted: 08/09/2016] [Indexed: 12/16/2022]
Abstract
Diabetes and obesity are prevalent in westernized countries. In both conditions, excessive fatty acid uptake by cardiomyocytes induces cardiac lipotoxicity, an important mechanism contributing to diabetic cardiomyopathy. This study investigated the effect of calpain disruption on cardiac lipotoxicity. Cardiac-specific capns1 knockout mice and their wild-type littermates (male, age of 4weeks) were fed a high fat diet (HFD) or normal diet for 20weeks. HFD increased body weight, altered blood lipid profiles and impaired glucose tolerance comparably in both capns1 knockout mice and their wild-type littermates. Calpain activity, cardiomyocyte cross-sectional areas, collagen deposition and triglyceride were significantly increased in HFD-fed mouse hearts, and these were accompanied by myocardial dysfunction and up-regulation of hypertrophic and fibrotic collagen genes as well as pro-inflammatory cytokines. These effects of HFD were attenuated by disruption of calpain in capns1 knockout mice. Mechanistically, deletion of capns1 in HFD-fed mouse hearts and disruption of calpain with calpain inhibitor-III, silencing of capn1, or deletion of capns1 in palmitate-stimulated cardiomyocytes prevented endoplasmic reticulum stress, apoptosis, cleavage of caspase-12 and junctophilin-2, and pro-inflammatory cytokine expression. Pharmacological inhibition of endoplasmic reticulum stress diminished palmitate-induced apoptosis and pro-inflammatory cytokine expression in cardiomyocytes. In summary, disruption of calpain prevents lipotoxicity-induced apoptosis in cardiomyocytes and cardiac injury in mice fed a HFD. The role of calpain is mediated, at least partially, through endoplasmic reticulum stress. Thus, calpain/endoplasmic reticulum stress may represent a new mechanism and potential therapeutic targets for cardiac lipotoxicity.
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Affiliation(s)
- Shengcun Li
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province 215123, China
| | - Lulu Zhang
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province 215123, China
| | - Rui Ni
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province 215123, China; Critical Illness Research, Lawson Health Research Institute, Western University, London, Ontario N6A 4G5, Canada; Department of Pathology and Laboratory Medicine, Western University, London, Ontario N6A 4G5, Canada
| | - Ting Cao
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province 215123, China
| | - Dong Zheng
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province 215123, China; Critical Illness Research, Lawson Health Research Institute, Western University, London, Ontario N6A 4G5, Canada; Department of Medicine, Western University, London, Ontario N6A 4G5, Canada
| | - Sidong Xiong
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province 215123, China
| | - Peter A Greer
- Division of Cancer Biology and Genetics, Queen's University Cancer Research Institute, Kingston, Ontario K7L 3N6, Canada; Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Guo-Chang Fan
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Tianqing Peng
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province 215123, China; Critical Illness Research, Lawson Health Research Institute, Western University, London, Ontario N6A 4G5, Canada; Department of Medicine, Western University, London, Ontario N6A 4G5, Canada; Department of Pathology and Laboratory Medicine, Western University, London, Ontario N6A 4G5, Canada.
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20
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Aromolaran AS, Colecraft HM, Boutjdir M. High-fat diet-dependent modulation of the delayed rectifier K(+) current in adult guinea pig atrial myocytes. Biochem Biophys Res Commun 2016; 474:554-559. [PMID: 27130822 DOI: 10.1016/j.bbrc.2016.04.113] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 04/20/2016] [Indexed: 12/11/2022]
Abstract
Obesity is associated with hyperlipidemia, electrical remodeling of the heart, and increased risk of supraventricular arrhythmias in both male and female patients. The delayed rectifier K(+) current (IK), is an important regulator of atrial repolarization. There is a paucity of studies on the functional role of IK in response to obesity. Here, we assessed the obesity-mediated functional modulation of IK in low-fat diet (LFD), and high-fat diet (HFD) fed adult guinea pigs. Guinea pigs were randomly divided into control and obese groups fed, ad libitum, with a LFD (10 kcal% fat) or a HFD (45 kcal% fat) respectively. Action potential duration (APD), and IK were studied in atrial myocytes and IKr and IKs in HEK293 cells using whole-cell patch clamp electrophysiology. HFD guinea pigs displayed a significant increase in body weight, total cholesterol and total triglycerides within 50 days. Atrial APD at 30% (APD30) and 90% (APD90) repolarization were shorter, while atrial IK density was significantly increased in HFD guinea pigs. Exposure to palmitic acid (PA) increased heterologously expressed IKr and IKs densities, while oleic acid (OA), severely reduced IKr and had no effect on IKs. The data are first to show that in obese guinea pigs abbreviated APD is due to increased IK density likely through elevations of PA. Our findings may have crucial implications for targeted treatment options for obesity-related arrhythmias.
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Affiliation(s)
- Ademuyiwa S Aromolaran
- Department of Physiology & Cellular Biophysics, Columbia University, New York, NY, United States
| | - Henry M Colecraft
- Department of Physiology & Cellular Biophysics, Columbia University, New York, NY, United States
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, United States; Department of Medicine, State University of New York Downstate Medical Center, Brooklyn, New York, NY, United States; Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York, NY, United States; Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn, New York, NY, United States; Department of Medicine, New York University School of Medicine, New York, NY, United States.
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21
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Imaging of myocardial fatty acid oxidation. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1535-43. [PMID: 26923433 DOI: 10.1016/j.bbalip.2016.02.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 02/19/2016] [Accepted: 02/20/2016] [Indexed: 02/06/2023]
Abstract
Myocardial fuel selection is a key feature of the health and function of the heart, with clear links between myocardial function and fuel selection and important impacts of fuel selection on ischemia tolerance. Radiopharmaceuticals provide uniquely valuable tools for in vivo, non-invasive assessment of these aspects of cardiac function and metabolism. Here we review the landscape of imaging probes developed to provide non-invasive assessment of myocardial fatty acid oxidation (MFAO). Also, we review the state of current knowledge that myocardial fatty acid imaging has helped establish of static and dynamic fuel selection that characterizes cardiac and cardiometabolic disease and the interplay between fuel selection and various aspects of cardiac function. This article is part of a Special Issue entitled: Heart Lipid Metabolism edited by G.D. Lopaschuk.
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22
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Free Fatty Acid Effects on the Atrial Myocardium: Membrane Ionic Currents Are Remodeled by the Disruption of T-Tubular Architecture. PLoS One 2015; 10:e0133052. [PMID: 26274906 PMCID: PMC4537212 DOI: 10.1371/journal.pone.0133052] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 06/22/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Epicardial adiposity and plasma levels of free fatty acids (FFAs) are elevated in atrial fibrillation, heart failure and obesity, with potentially detrimental effects on myocardial function. As major components of epicardial fat, FFAs may be abnormally regulated, with a potential to detrimentally modulate electro-mechanical function. The cellular mechanisms underlying such effects of FFAs are unknown. OBJECTIVE To determine the mechanisms underlying electrophysiological effects of palmitic (PA), stearic (SA) and oleic (OA) FFAs on sheep atrial myocytes. METHODS We used electrophysiological techniques, numerical simulations, biochemistry and optical imaging to examine the effects of acutely (≤ 15 min), short-term (4-6 hour) or 24-hour application of individual FFAs (10 μM) on isolated ovine left atrial myocytes (LAMs). RESULTS Acute and short-term incubation in FFAs resulted in no differences in passive or active properties of isolated left atrial myocytes (LAMs). 24-hour application had differential effects depending on the FFA. PA did not affect cellular passive properties but shortened (p<0.05) action potential duration at 30% repolarization (APD30). APD50 and APD80 were unchanged. SA had no effect on resting membrane potential but reduced membrane capacitance by 15% (p<0.05), and abbreviated APD at all values measured (p≤0.001). OA did not significantly affect passive or active properties of LAMs. Measurement of the major voltage-gated ion channels in SA treated LAMs showed a ~60% reduction (p<0.01) of the L-type calcium current (ICa-L) and ~30% reduction (p<0.05) in the transient outward potassium current (ITO). A human atrial cell model recapitulated SA effects on APD. Optical imaging showed that SA incubated for 24 hours altered t-tubular structure in isolated cells (p<0.0001). CONCLUSIONS SA disrupts t-tubular architecture and remodels properties of membrane ionic currents in sheep atrial myocytes, with potential implications in arrhythmogenesis.
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23
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Schooley JF, Namboodiri AMA, Cox RT, Bünger R, Flagg TP. Acetate transiently inhibits myocardial contraction by increasing mitochondrial calcium uptake. BMC PHYSIOLOGY 2014; 14:12. [PMID: 25488103 PMCID: PMC4274725 DOI: 10.1186/s12899-014-0012-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 11/24/2014] [Indexed: 02/02/2023]
Abstract
Background There is a close relationship between cardiovascular disease and cardiac energy metabolism, and we have previously demonstrated that palmitate inhibits myocyte contraction by increasing Kv channel activity and decreasing the action potential duration. Glucose and long chain fatty acids are the major fuel sources supporting cardiac function; however, cardiac myocytes can utilize a variety of substrates for energy generation, and previous studies demonstrate the acetate is rapidly taken up and oxidized by the heart. In this study, we tested the effects of acetate on contractile function of isolated mouse ventricular myocytes. Results Acute exposure of myocytes to 10 mM sodium acetate caused a marked, but transient, decrease in systolic sarcomere shortening (1.49 ± 0.20% vs. 5.58 ± 0.49% in control), accompanied by a significant increase in diastolic sarcomere length (1.81 ± 0.01 μm vs. 1.77 ± 0.01 μm in control), with a near linear dose response in the 1–10 mM range. Unlike palmitate, acetate caused no change in action potential duration; however, acetate markedly increased mitochondrial Ca2+ uptake. Moreover, pretreatment of cells with the mitochondrial Ca2+ uptake blocker, Ru-360 (10 μM), markedly suppressed the effect of acetate on contraction. Conclusions Lehninger and others have previously demonstrated that the anions of weak aliphatic acids such as acetate stimulate Ca2+ uptake in isolated mitochondria. Here we show that this effect of acetate appears to extend to isolated cardiac myocytes where it transiently modulates cell contraction.
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Affiliation(s)
- James F Schooley
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University for the Health Sciences, 4301 Jones Bridge Road, Rm. C-2114, Bethesda, 20814, MD, USA.
| | - Aryan M A Namboodiri
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University for the Health Sciences, 4301 Jones Bridge Road, Rm. C-2114, Bethesda, 20814, MD, USA.
| | - Rachel T Cox
- Department of Biochemistry and Molecular Biology, Uniformed Services University for the Health Sciences, Bethesda, 20814, MD, USA.
| | - Rolf Bünger
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University for the Health Sciences, 4301 Jones Bridge Road, Rm. C-2114, Bethesda, 20814, MD, USA.
| | - Thomas P Flagg
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University for the Health Sciences, 4301 Jones Bridge Road, Rm. C-2114, Bethesda, 20814, MD, USA.
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24
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Bhatt NM, Aon MA, Tocchetti CG, Shen X, Dey S, Ramirez-Correa G, O'Rourke B, Gao WD, Cortassa S. Restoring redox balance enhances contractility in heart trabeculae from type 2 diabetic rats exposed to high glucose. Am J Physiol Heart Circ Physiol 2014; 308:H291-302. [PMID: 25485897 DOI: 10.1152/ajpheart.00378.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Hearts from type 2 diabetic (T2DM) subjects are chronically subjected to hyperglycemia and hyperlipidemia, both thought to contribute to oxidizing conditions and contractile dysfunction. How redox alterations and contractility interrelate, ultimately diminishing T2DM heart function, remains poorly understood. Herein we tested whether the fatty acid palmitate (Palm), in addition to its energetic contribution, rescues function by improving redox [glutathione (GSH), NAD(P)H, less oxidative stress] in T2DM rat heart trabeculae subjected to high glucose. Using cardiac trabeculae from Zucker Diabetic Fatty (ZDF) rats, we assessed the impact of low glucose (EG) and high glucose (HG), in absence or presence of Palm or insulin, on force development, energetics, and redox responses. We found that in EG ZDF and lean trabeculae displayed similar contractile work, yield of contractile work (Ycw), representing the ratio of force time integral over rate of O2 consumption. Conversely, HG had a negative impact on Ycw, whereas Palm, but not insulin, completely prevented contractile loss. This effect was associated with higher GSH, less oxidative stress, and augmented matrix GSH/thioredoxin (Trx) in ZDF mitochondria. Restoration of myocardial redox with GSH ethyl ester also rescued ZDF contractile function in HG, independently from Palm. These results support the idea that maintained redox balance, via increased GSH and Trx antioxidant activities to resist oxidative stress, is an essential protective response of the diabetic heart to keep contractile function.
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Affiliation(s)
- Niraj M Bhatt
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Miguel A Aon
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Carlo G Tocchetti
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Xiaoxu Shen
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Swati Dey
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Genaro Ramirez-Correa
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Brian O'Rourke
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Wei Dong Gao
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sonia Cortassa
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
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25
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Abstract
OBJECTIVES Bolus infusion of lipid emulsion can reverse cardiac pharmacotoxicity caused by local anesthetics and other lipophilic drugs. The mechanisms of this effect are not completely elucidated. The authors test the hypothesis that lipid emulsion infusion exerts direct, positive inotropic effects. DESIGN Prospective, randomized animal study. SETTING University research laboratory. SUBJECTS Adult male Sprague-Dawley rats. INTERVENTIONS Rats anesthetized with isoflurane were given intravenous infusions (9 mL/kg over 1 min) of either 20% soybean oil-based emulsion or saline. MEASUREMENTS AND MAIN RESULTS Arterial pressure and aortic flow were measured continuously in intact animals. Lipid infusion increased aortic flow and arterial pressure faster and to a greater degree than did the same volume of saline infusion. Isolated rat hearts were studied using an isovolumetric, constant flow, nonrecirculating system. Left ventricular pressure was monitored. The infusion of lipid emulsion in the isolated heart dose-dependently increased rate pressure product, dP/dt, -dP/dt, and myocardial oxygen demand. CONCLUSIONS Lipid emulsion exerts rapid, positive inotropic and positive lusitropic effects in both intact animal and isolated heart models. We hypothesize that this inotropy and the resulting increase in tissue blood flow contribute to the phenomenon of lipid reversal of cardiac toxicity caused by drug overdose.
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26
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CD36 inhibition prevents lipid accumulation and contractile dysfunction in rat cardiomyocytes. Biochem J 2013; 448:43-53. [PMID: 22780108 DOI: 10.1042/bj20120060] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
An increased cardiac fatty acid supply and increased sarcolemmal presence of the long-chain fatty acid transporter CD36 are associated with and contribute to impaired cardiac insulin sensitivity and function. In the present study we aimed at preventing the development of insulin resistance and contractile dysfunction in cardiomyocytes by blocking CD36-mediated palmitate uptake. Insulin resistance and contractile dysfunction were induced in primary cardiomyocytes by 48 h incubation in media containing either 100 nM insulin (high insulin; HI) or 200 μM palmitate (high palmitate; HP). Under both culture conditions, insulin-stimulated glucose uptake and Akt phosphorylation were abrogated or markedly reduced. Furthermore, cardiomyocytes cultured in each medium displayed elevated sarcolemmal CD36 content, increased basal palmitate uptake, lipid accumulation and decreased sarcomere shortening. Immunochemical CD36 inhibition enhanced basal glucose uptake and prevented elevated basal palmitate uptake, triacylglycerol accumulation and contractile dysfunction in cardiomyocytes cultured in either medium. Additionally, CD36 inhibition prevented loss of insulin signalling in cells cultured in HP, but not in HI medium. In conclusion, CD36 inhibition prevents lipid accumulation and lipid-induced contractile dysfunction in cardiomyocytes, but probably independently of effects on insulin signalling. Nonetheless, pharmacological CD36 inhibition may be considered as a treatment strategy to counteract impaired functioning of the lipid-loaded heart.
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27
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Glatz JFC, Angin Y, Steinbusch LKM, Schwenk RW, Luiken JJFP. CD36 as a target to prevent cardiac lipotoxicity and insulin resistance. Prostaglandins Leukot Essent Fatty Acids 2013; 88:71-7. [PMID: 22580174 DOI: 10.1016/j.plefa.2012.04.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 04/19/2012] [Accepted: 04/20/2012] [Indexed: 11/17/2022]
Abstract
The fatty acid transporter and scavenger receptor CD36 is increasingly being implicated in the pathogenesis of insulin resistance and its progression towards type 2 diabetes and associated cardiovascular complications. The redistribution of CD36 from intracellular stores to the plasma membrane is one of the earliest changes occurring in the heart during diet induced obesity and insulin resistance. This elicits an increased rate of fatty acid uptake and enhanced incorporation into triacylglycerol stores and lipid intermediates to subsequently interfere with insulin-induced GLUT4 recruitment (i.e., insulin resistance). In the present paper we discuss the potential of CD36 to serve as a target to rectify abnormal myocardial fatty acid uptake rates in cardiac lipotoxic diseases. Two approaches are described: (i) immunochemical inhibition of CD36 present at the sarcolemma and (ii) interference with the subcellular recycling of CD36. Using in vitro model systems of high-fat diet induced insulin resistance, the results indicate the feasibility of using CD36 as a target for adaptation of cardiac metabolic substrate utilization. In conclusion, CD36 deserves further attention as a promising therapeutic target to redirect fatty acid fluxes in the body.
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Affiliation(s)
- Jan F C Glatz
- Department of Molecular Genetics, Cardiovascular Research Institute Maastricht CARIM, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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28
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Abstract
Endothelial injury related to oxidative stress is a key event in cardiovascular diseases, such as hypertension and atherosclerosis. The activation of the redox-sensitive Kv1.5 potassium channel mediates mitochondrial reactive oxygen species (ROS)-induced apoptosis in vascular smooth muscle cells and some cancer cells. Kv1.5 channel is therefore taken as a new potential therapeutic target for pulmonary hypertension and cancers. Although Kv1.5 is abundantly expressed in vascular endothelium, there is little knowledge of its role in endothelial injury related to oxidative stress. We found that DPO-1, a specific inhibitor of Kv1.5, attenuated H2O2-evoked endothelial cell apoptosis in an in vivo rat carotid arterial model. In human umbilical vein endothelial cells (HUVECs) and human pulmonary arterial endothelial cells (HPAECs), angiotensin II and oxLDL time- or concentration-dependently enhanced Kv1.5 protein expression in parallel with the production of intracellular ROS and endothelial cell injury. Moreover, siRNA-mediated knockdown of Kv1.5 attenuated, whereas adenovirus-mediated Kv1.5 cDNA overexpression enhanced oxLDL–induced cellular damage, NADPH oxidase and mitochondria-derived ROS production and restored the decrease in protein expression of mitochondria uncoupling protein 2 (UCP2). Collectively, these data suggest that Kv1.5 may play an important role in oxidative vascular endothelial injury.
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29
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Veronica G, Esther RRM. Aging, metabolic syndrome and the heart. Aging Dis 2012; 3:269-279. [PMID: 22724085 PMCID: PMC3375083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 03/10/2012] [Accepted: 03/11/2012] [Indexed: 06/01/2023] Open
Abstract
Aging is accelerated when metabolic and cardiovascular diseases (CVD) are present and the risk of these diseases increases with age. Many predisposing conditions which increase in prevalence during aging, such as obesity, insulin resistance, inflammation, changes in the activity of the hypothalamus-hypophysis suprarenal axis, stress and hypertension also contribute to increase prevalence of metabolic syndrome (MS) and CVD and will be discussed in this paper. Aging and MS are frequently accompanied by several pathological conditions and some associated phenomena such as increased lipoperoxidation, generation of free radicals, increased peroxidation of nitric oxide (NO) to its toxic species, and others, resulting from oxidative stress which significantly alter the incidence of CVD. The better knowledge of mechanisms linking MS to increased CVD prevalence has led to new predictive measures and to the study of different possible new therapeutic strategies in elderly patients and patients with MS. Preventing and treating MS and CVD would be useful in promoting normal aging.
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Affiliation(s)
- Guarner Veronica
- Correspondence should be addressed to: Verónica Guarner Ph.D., Departamento de Fisiología, Instituto Nacional de Cardiología “Ignacio Chávez”. Juan Badiano 1, Tlalpan México, D.F. 14080, México. E-mail:
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30
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Wang G, Li W, Lu X, Zhao X. Riboflavin alleviates cardiac failure in Type I diabetic cardiomyopathy. Heart Int 2011; 6:e21. [PMID: 22355488 PMCID: PMC3282438 DOI: 10.4081/hi.2011.e21] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 10/19/2011] [Accepted: 10/25/2011] [Indexed: 12/17/2022] Open
Abstract
Heart failure (HF) is a common and serious comorbidity of diabetes. Oxidative stress has been associated with the pathogenesis of chronic diabetic complications including cardiomyopathy. The ability of antioxidants to inhibit injury has raised the possibility of new therapeutic treatment for diabetic heart diseases. Riboflavin constitutes an essential nutrient for humans and animals and it is an important food additive. Riboflavin, a precursor of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), enhances the oxidative folding and subsequent secretion of proteins. The objective of this study was to investigate the cardioprotective effect of riboflavin in diabetic rats. Diabetes was induced in 30 rats by a single injection of streptozotocin (STZ) (70 mg /kg). Riboflavin (20 mg/kg) was orally administered to animals immediately after induction of diabetes and was continued for eight weeks. Rats were examined for diabetic cardiomyopathy by left ventricular (LV) remadynamic function. Myocardial oxidative stress was assessed by measuring the activity of superoxide dismutase (SOD), the level of malondialdehyde (MDA) as well as heme oxygenase-1 (HO-1) protein level. Myocardial connective tissue growth factor (CTGF) level was measured by Western blot in all rats at the end of the study. In the untreated diabetic rats, left ventricular systolic pressure (LVSP) rate of pressure rose (+dp/dt), and rate of pressure decay (−dp/dt) were depressed while left ventricular end-diastolic pressure (LVEDP) was increased, which indicated the reduced left ventricular contractility and slowing of left ventricular relaxation. The level of SOD decreased, CTGF and HO-1 protein expression and MDA content rose. Riboflavin treatment significantly improved left ventricular systolic and diastolic function in diabetic rats, there were persistent increases in significant activation of SOD and the level of HO-1 protein, and a decrease in the level of CTGF. These results suggest that riboflavin treatment ameliorates myocardial function and improves heart oxidant status, whereas raising myocardial HO-1 and decreasing myocardial CTGF levels have beneficial effects on diabetic cardiomyopathy.
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Affiliation(s)
- Guoguang Wang
- Department of Pathophysiology, Wannan Medical College, Wuhu, China
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31
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Abstract
Type 2 diabetes and obesity are associated with systemic inflammation, generalized enlargement of fat depots, and uncontrolled release of fatty acids (FA) into the circulation. These features support the occurrence of cardiac adiposity, which is characterized by an increase in intramyocardial triglyceride content and an enlargement of the volume of fat surrounding the heart and vessels. Both events may initially serve as protective mechanisms to portion energy, but their excessive expansion can lead to myocardial damage and heart disease. FA overload promotes FA oxidation and the accumulation of triglycerides and metabolic intermediates, which can impair calcium signaling, β-oxidation, and glucose utilization. This leads to damaged mitochondrial function and increased production of reactive oxygen species, pro-apoptotic, and inflammatory molecules, and finally to myocardial inflammation and dysfunction. Triglyceride accumulation is associated with left ventricular hypertrophy and dysfunction. The enlargement of epicardial fat in patients with metabolic disorders, and coronary artery disease, is associated with the release of proinflammatory and proatherogenic cytokines to the subtending tissues. In this review, we examine the evidence supporting a causal relationship linking FA overload and cardiac dysfunction. Also, we disentangle the separate roles of FA oxidation and triglyceride accumulation in causing cardiac damage. Finally, we focus on the mechanisms of inflammation development in the fatty heart, before summarizing the available evidence in humans. Current literature confirms the dual (protective and detrimental) role of cardiac fat, and suggests prospective studies to establish the pathogenetic (when and how) and possible prognostic value of this potential biomarker in humans.
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Affiliation(s)
- Maria A Guzzardi
- Institute of Clinical Physiology, National Research Council (CNR), Via Moruzzi 1, 56124 Pisa, Italy
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32
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Razani B, Zhang H, Schulze PC, Schilling JD, Verbsky J, Lodhi IJ, Topkara VK, Feng C, Coleman T, Kovacs A, Kelly DP, Saffitz JE, Dorn GW, Nichols CG, Semenkovich CF. Fatty acid synthase modulates homeostatic responses to myocardial stress. J Biol Chem 2011; 286:30949-30961. [PMID: 21757749 DOI: 10.1074/jbc.m111.230508] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Fatty acid synthase (FAS) promotes energy storage through de novo lipogenesis and participates in signaling by the nuclear receptor PPARα in noncardiac tissues. To determine if de novo lipogenesis is relevant to cardiac physiology, we generated and characterized FAS knockout in the myocardium (FASKard) mice. FASKard mice develop normally, manifest normal resting heart function, and have normal cardiac PPARα signaling as well as fatty acid oxidation. However, they decompensate with stress. Most die within 1 h of transverse aortic constriction, probably due to arrhythmia. Voltage clamp measurements of FASKard cardiomyocytes show hyperactivation of L-type calcium channel current that could not be reversed with palmitate supplementation. Of the classic regulators of this current, Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) but not protein kinase A signaling is activated in FASKard hearts, and knockdown of FAS in cultured cells activates CaMKII. In addition to being intolerant of the stress of acute pressure, FASKard hearts were also intolerant of the stress of aging, reflected as persistent CaMKII hyperactivation, progression to dilatation, and premature death by ∼1 year of age. CaMKII signaling appears to be pathogenic in FASKard hearts because inhibition of its signaling in vivo rescues mice from early mortality after transverse aortic constriction. FAS was also increased in two mechanistically distinct mouse models of heart failure and in the hearts of humans with end stage cardiomyopathy. These data implicate a novel relationship between FAS and calcium signaling in the heart and suggest that FAS induction in stressed myocardium represents a compensatory response to protect cardiomyocytes from pathological calcium flux.
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Affiliation(s)
- Babak Razani
- Divisions of Endocrinology, Metabolism, and Lipid Research, Washington University, St. Louis, Missouri 63110; Cardiology, Washington University, St. Louis, Missouri 63110
| | - Haixia Zhang
- Department of Cell Biology and Physiology, Washington University, St. Louis, Missouri 63110
| | | | | | - John Verbsky
- Department of Cell Biology and Physiology, Washington University, St. Louis, Missouri 63110
| | - Irfan J Lodhi
- Divisions of Endocrinology, Metabolism, and Lipid Research, Washington University, St. Louis, Missouri 63110
| | - Veli K Topkara
- Cardiology, Washington University, St. Louis, Missouri 63110
| | - Chu Feng
- Divisions of Endocrinology, Metabolism, and Lipid Research, Washington University, St. Louis, Missouri 63110
| | - Trey Coleman
- Divisions of Endocrinology, Metabolism, and Lipid Research, Washington University, St. Louis, Missouri 63110
| | - Attila Kovacs
- Cardiology, Washington University, St. Louis, Missouri 63110
| | - Daniel P Kelly
- Sanford-Burnham Medical Research Institute, Orlando, Florida 32827
| | - Jeffrey E Saffitz
- Department of Pathology, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215
| | - Gerald W Dorn
- Center for Pharmacogenomics, Washington University, St. Louis, Missouri 63110
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University, St. Louis, Missouri 63110
| | - Clay F Semenkovich
- Divisions of Endocrinology, Metabolism, and Lipid Research, Washington University, St. Louis, Missouri 63110; Department of Cell Biology and Physiology, Washington University, St. Louis, Missouri 63110.
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33
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Boardman NT, Larsen TS, Severson DL, Essop MF, Aasum E. Chronic and acute exposure of mouse hearts to fatty acids increases oxygen cost of excitation-contraction coupling. Am J Physiol Heart Circ Physiol 2011; 300:H1631-6. [DOI: 10.1152/ajpheart.01190.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The aim of the present study was to evaluate the underlying processes involved in the oxygen wasting induced by inotropic drugs and acute and chronic elevation of fatty acid (FA) supply, using unloaded perfused mouse hearts from normal and type 2 diabetic ( db/db) mice. We found that an acute elevation of the FA supply in normal hearts, as well as a chronic (in vivo) exposure to elevated FA as in db/db hearts, increased myocardial oxygen consumption (MV̇o2unloaded) due to increased oxygen cost for basal metabolism and for excitation-contraction (EC) coupling. Isoproterenol stimulation, on top of a high FA supply, led to an additive increase in MV̇o2unloaded, because of a further increase in oxygen cost for EC coupling. In db/db hearts, the acute elevation of FA did not further increase MV̇o2. Since the elevation in the FA supply is accompanied by increased rates of myocardial FA oxidation, the present study compared MV̇o2 following increased FA load versus FA oxidation rate by exposing normal hearts to normal and high FA concentration (NF and HF, respectively) and to compounds that either stimulate (GW-610742) or inhibit [dichloroacetate (DCA)] FA oxidation. While HF and NF + GW-610742 increased FA oxidation to the same extent, only HF increased MV̇o2unloaded. Although DCA counteracted the HF-induced increase in FA oxidation, DCA did not reduce MV̇o2unloaded. Thus, in normal hearts, acute FA-induced oxygen waste is 1) due to an increase in the oxygen cost for both basal metabolism and EC coupling and 2) not dependent on the myocardial FA oxidation rate per se, but on processes initiated by the presence of FAs. In diabetic hearts, chronic exposure to elevated circulating FAs leads to adaptations that afford protection against the detrimental effect of an acute FA load, suggesting different underlying mechanisms behind the increased MV̇o2 following acute and chronic FA load.
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Affiliation(s)
- Neoma T. Boardman
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Terje S. Larsen
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - David L. Severson
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Canada; and
| | - M. Faadiel Essop
- Cardio-Metabolic Research Group, Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
| | - Ellen Aasum
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
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34
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Liu J, Kim KH, London B, Morales MJ, Backx PH. Dissection of the voltage-activated potassium outward currents in adult mouse ventricular myocytes: I to,f, I to,s, I K,slow1, I K,slow2, and I ss. Basic Res Cardiol 2011; 106:189-204. [DOI: 10.1007/s00395-010-0134-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 10/27/2010] [Accepted: 11/04/2010] [Indexed: 11/30/2022]
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35
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Nediani C, Raimondi L, Borchi E, Cerbai E. Nitric oxide/reactive oxygen species generation and nitroso/redox imbalance in heart failure: from molecular mechanisms to therapeutic implications. Antioxid Redox Signal 2011; 14:289-331. [PMID: 20624031 DOI: 10.1089/ars.2010.3198] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Adaptation of the heart to intrinsic and external stress involves complex modifications at the molecular and cellular levels that lead to tissue remodeling, functional and metabolic alterations, and finally to failure depending upon the nature, intensity, and chronicity of the stress. Reactive oxygen species (ROS) have long been considered as merely harmful entities, but their role as second messengers has gradually emerged. At the same time, our comprehension of the multifaceted role of nitric oxide (NO) and the related reactive nitrogen species (RNS) has been upgraded. The tight interlay between ROS and RNS suggests that their imbalance may implicate the impairment in physiological NO/redox-based signaling that contributes to the failing of the cardiovascular system. This review initially provides basic concepts on the role of nitroso/oxidative stress in the pathophysiology of heart failure with a particular focus on sources of ROS/RNS, their downstream targets, and endogenous modulators. Then, the role of NO/redox regulation of cardiomyocyte function, including calcium homeostasis, electrogenesis, and insulin signaling pathways, is described. Finally, an overview of old and emerging therapeutic opportunities in heart failure is presented, focusing on modulation of NO/redox mechanisms and discussing benefits and limitations.
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Affiliation(s)
- Chiara Nediani
- Department of Biochemical Sciences, University of Florence, Florence, Italy.
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36
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What we know and do not know about sex and cardiac disease. J Biomed Biotechnol 2010; 2010:562051. [PMID: 20445744 PMCID: PMC2860154 DOI: 10.1155/2010/562051] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 02/16/2010] [Indexed: 12/11/2022] Open
Abstract
Cardiovascular disease (CVD) remains the single leading cause of death in both men and women. A large proportion of the population with CVD will die with a diagnosis of congestive heart failure (CHF). It is becoming increasingly recognized that sex differences exist in the etiology, development, and outcome of CHF. For example, compared to male counterparts, women that present with CHF are typically older and have systolic cardiac function that is not impaired. Despite a growing body of literature addressing the underlying mechanisms of sex dimorphisms in cardiac disease, there remain significant inconsistencies reported in these studies. Given that the development of CHF results from the complex integration of genetic and nongenetic cues, it is not surprising that the elucidation and subsequent identification of molecular mechanisms remains unclear. In this review, key aspects of sex differences in CVD and CHF will be highlighted with an emphasis on some of the unanswered questions regarding these differences. The contention is presented that it becomes critical to reference cellular mechanisms within the context of each sex to better understand these sex dimorphisms.
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