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Beale PK, Marsh KJ, Foley WJ, Moore BD. A hot lunch for herbivores: physiological effects of elevated temperatures on mammalian feeding ecology. Biol Rev Camb Philos Soc 2017; 93:674-692. [DOI: 10.1111/brv.12364] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/25/2017] [Accepted: 08/09/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Phillipa K. Beale
- Research School of Biology The Australian National University Canberra Australian Capital Territory 2601 Australia
| | - Karen J. Marsh
- Research School of Biology The Australian National University Canberra Australian Capital Territory 2601 Australia
| | - William J. Foley
- Research School of Biology The Australian National University Canberra Australian Capital Territory 2601 Australia
- Animal Ecology and Conservation University of Hamburg, Martin‐Luther‐King‐Platz 3 20146 Hamburg Germany
| | - Ben D. Moore
- Hawkesbury Institute for the Environment Western Sydney University, Locked bag 1797 Penrith New South Wales 2751 Australia
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52
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Nie L, Yuan XL, Jiang KT, Jiang YH, Yuan J, Luo L, Cui SW, Sun C. Salsalate Activates Skeletal Muscle Thermogenesis and Protects Mice from High-Fat Diet Induced Metabolic Dysfunction. EBioMedicine 2017; 23:136-145. [PMID: 28801239 PMCID: PMC5605325 DOI: 10.1016/j.ebiom.2017.08.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/31/2017] [Accepted: 08/03/2017] [Indexed: 12/30/2022] Open
Abstract
Salsalate plays beneficial roles for ameliorating hyperglycemia and dyslipidemia in type 2 diabetes patients, but the underlying mechanisms are still poorly understood. In this study, by administering salsalate to mice fed with high fat diet and examining how salsalate rectifies metabolic dysfunction in these obese mice, we found that salsalate stimulated body temperature and attenuated body weight gain without affecting food intake. Our results showed that salsalate application decreased lipid accumulation in liver and epididymal white adipose tissue (eWAT), inhibited hepatic gluconeogenesis and improved insulin signaling transduction in eWAT. In addition, salsalate increased the expression of genes related to glucose and fatty acid transport and oxidation in skeletal muscle. Our results also showed that expression of genes in mitochondrial uncoupling and mitochondrial electron transport are strengthened by salsalate. Moreover, sarcolipin (Sln) and sarcoplasmic reticulum Ca2 + ATPase 2 (Serca2) in skeletal muscle were enhanced in salsalate-treated mice. Together, our data suggest that the beneficial metabolic effects of salsalate may depend, at least in part, on skeletal muscle thermogenesis via activation of mitochondrial uncoupling and the axis of Sln/Serca2a. Salsalate improves metabolic dysfunction in high-fat diet induced obese mice. Salsalate stimulates energy expenditure by activating skeletal muscle thermogenesis.
It has been well documented that salicylate-based compounds play beneficial roles for treating obesity-related metabolic syndromes and enhanced energy expenditure was thought to be one of the underlying mechanisms. However, the tissues targeted by salicylate for energy expenditure and the involved mechanisms are still not clear. Our data show that, by activating mitochondrial uncoupling and the axis of Sln/Serca2, salsalate stimulates skeletal muscle thermogenesis in high-fat diet induced obese mice. Therefore, we suggest skeletal muscle thermogenesis may account for salsalate-induced energy expenditure and its beneficial metabolic effects in type 2 diabetes patients.
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Affiliation(s)
- Li Nie
- Department of Endocrinology and Metabolic Diseases, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
| | - Xin-Lu Yuan
- Department of Endocrinology and Metabolic Diseases, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
| | - Ke-Tao Jiang
- Key Laboratory for Neuroregeneration of Jiangsu Province, Ministry of Education, Nantong University, 19 Qixiu Road, Nantong, Jiangsu 226001, China
| | - Yu-Hui Jiang
- Key Laboratory for Neuroregeneration of Jiangsu Province, Ministry of Education, Nantong University, 19 Qixiu Road, Nantong, Jiangsu 226001, China
| | - Jin Yuan
- Department of Endocrinology and Metabolic Diseases, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China
| | - Lan Luo
- Department of Geratology, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, China
| | - Shi-Wei Cui
- Department of Endocrinology and Metabolic Diseases, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China.
| | - Cheng Sun
- Key Laboratory for Neuroregeneration of Jiangsu Province, Ministry of Education, Nantong University, 19 Qixiu Road, Nantong, Jiangsu 226001, China.
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Takahashi N, Kimura AP, Naito S, Yoshida M, Kumano O, Suzuki T, Itaya S, Moriya M, Tsuji M, Ieko M. Sarcolipin expression is repressed by endoplasmic reticulum stress in C2C12 myotubes. J Physiol Biochem 2017; 73:531-538. [DOI: 10.1007/s13105-017-0578-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 06/29/2017] [Indexed: 01/08/2023]
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54
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Periasamy M, Maurya SK, Sahoo SK, Singh S, Reis FCG, Bal NC. Role of SERCA Pump in Muscle Thermogenesis and Metabolism. Compr Physiol 2017. [DOI: 10.1002/cphy.c160030] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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55
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Dong Z, Zhao P, Xu M, Zhang C, Guo W, Chen H, Tian J, Wei H, Lu R, Cao T. Astragaloside IV alleviates heart failure via activating PPARα to switch glycolysis to fatty acid β-oxidation. Sci Rep 2017; 7:2691. [PMID: 28578382 PMCID: PMC5457407 DOI: 10.1038/s41598-017-02360-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/10/2017] [Indexed: 01/01/2023] Open
Abstract
In heart failure (HF), energy metabolism pathway in cardiac muscle changes from fatty acid β-oxidation to glycolysis. However, the exact mechanism is unknown. Sarcoendoplasmic reticulum Ca2+α ATPase (SERCA) expression is downregulated and mitochondrial function is reduced in HF, perhaps partly due to a substantially reduced energy supply for excitation–contraction coupling resulting from a lower fatty acid β-oxidation rate. We investigated whether Astragaloside IV can activate peroxisome proliferator-activated receptor alpha (PPARα) to stimulate fatty acid β-oxidation and increase cardiac energy production, improving mitochondrial function and the efficiency of SERCA in HF. In pressure overload-induced HF mice and isolated hypertrophic myocardial cells, fatty acid β-oxidation and heart function were substantially strengthened following Astragaloside IV treatment, as demonstrated by the increased expression of PPARα and SERCA2a. In vitro, Astragaloside IV regulated energy metabolism by increasing ATP production and enhancing mitochondrial function, attributable to increased oxygen consumption and slightly increased mitochondrial Ca2+ uptake. In HF, Astragaloside IV switched glycolysis to fatty acid β-oxidation, as confirmed by reduced anaerobic glycolysis and an increased oxygen consumption ratio. These results suggest that Astragaloside IV can stimulate fatty acid β-oxidation and improve mitochondrial function, which may present a novel cardioprotective treatment that inhibits the progress of HF.
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Affiliation(s)
- Zhiwei Dong
- Institute of Burn Research, Southwest Hospital, State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Pei Zhao
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Ming Xu
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Chen Zhang
- Division of Cardiothoracic Surgery, Baylor college of medicine, Houston, Texas, USA
| | - Wei Guo
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Huihua Chen
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Jing Tian
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Hongchang Wei
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Rong Lu
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China.
| | - Tongtong Cao
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China.
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56
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Structure-Function Relationship of the SERCA Pump and Its Regulation by Phospholamban and Sarcolipin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 981:77-119. [DOI: 10.1007/978-3-319-55858-5_5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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57
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Pant M, Bal NC, Periasamy M. Sarcolipin: A Key Thermogenic and Metabolic Regulator in Skeletal Muscle. Trends Endocrinol Metab 2016; 27:881-892. [PMID: 27637585 PMCID: PMC5424604 DOI: 10.1016/j.tem.2016.08.006] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/19/2016] [Accepted: 08/22/2016] [Indexed: 12/14/2022]
Abstract
Skeletal muscle constitutes ∼40% of body mass and has the capacity to play a major role as thermogenic, metabolic, and endocrine organ. In addition to shivering, muscle also contributes to nonshivering thermogenesis via futile sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA) activity. Sarcolipin (SLN), a regulator of SERCA activity in muscle, plays an important role in regulating muscle thermogenesis and metabolism. Uncoupling of SERCA by SLN increases ATP hydrolysis and heat production, and contributes to temperature homeostasis. SLN also affects whole-body metabolism and weight gain in mice, and is upregulated in various muscle diseases including muscular dystrophy, suggesting a role for SLN during increased metabolic demand. In this review we also highlight the physiological roles of skeletal muscle beyond contraction.
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Affiliation(s)
- Meghna Pant
- Department of Physiology and Cell Biology, Ohio State University, Columbus, OH, USA
| | - Naresh C Bal
- Sanford Burnham Medical Research Institute at Lake Nona, Orlando, FL, USA; School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | - Muthu Periasamy
- Department of Physiology and Cell Biology, Ohio State University, Columbus, OH, USA; Sanford Burnham Medical Research Institute at Lake Nona, Orlando, FL, USA.
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58
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Autry JM, Thomas DD, Espinoza-Fonseca LM. Sarcolipin Promotes Uncoupling of the SERCA Ca 2+ Pump by Inducing a Structural Rearrangement in the Energy-Transduction Domain. Biochemistry 2016; 55:6083-6086. [PMID: 27731980 PMCID: PMC5506494 DOI: 10.1021/acs.biochem.6b00728] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have performed microsecond (μs) molecular dynamics simulation (MDS) to identify structural mechanisms for sarcolipin (SLN) uncoupling of Ca2+ transport from ATP hydrolysis for the sarcoplasmic reticulum Ca2+-ATPase (SERCA). SLN regulates muscle metabolism and energy expenditure to provide resistance against diet-induced obesity and extreme cold. MDS demonstrated that the cytosolic domain of SLN induces a salt bridge-mediated structural rearrangement in the energy-transduction domain of SERCA. We propose that this structural change uncouples SERCA by perturbing Ca2+ occlusion at residue E309 in transport site II, thus facilitating Ca2+ backflux to the cytosol. Our results have important implications for designing muscle-based therapies for human obesity.
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Affiliation(s)
- Joseph M. Autry
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455
- Biophysical Technology Center, University of Minnesota, Minneapolis, MN 55455
| | - David D. Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455
| | - L. Michel Espinoza-Fonseca
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455
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59
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Bonilla IM, Nishijima Y, Vargas-Pinto P, Baine SH, Sridhar A, Li C, Billman GE, Carnes CA. Chronic Omega-3 Polyunsaturated Fatty Acid Treatment Variably Affects Cellular Repolarization in a Healed Post-MI Arrhythmia Model. Front Physiol 2016; 7:225. [PMID: 27378936 PMCID: PMC4906012 DOI: 10.3389/fphys.2016.00225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 05/30/2016] [Indexed: 01/22/2023] Open
Abstract
Introduction: Over the last 40 years omega-3 polyunsaturated fatty acids (PUFAs) have been shown to be anti-arrhythmic or pro-arrhythmic depending on the method and duration of administration and model studied. We previously reported that omega-3 PUFAs do not confer anti-arrhythmic properties and are pro-arrhythmic in canine model of sudden cardiac death (SCD). Here, we evaluated the effects of chronic omega-3 PUFA treatment in post-MI animals susceptible (VF+) or resistant (VF−) to ventricular tachyarrhythmias. Methods: Perforated patch clamp techniques were used to measure cardiomyocyte action potential durations (APD) at 50 and 90% repolarization and short term variability of repolarization. The early repolarizing transient outward potassium current Ito was also studied. Results: Omega-3 PUFAs prolonged the action potential in VF− myocytes at both 50 and 90% repolarization. Short term variability of repolarization was increased in both untreated and treated VF− myocytes vs. controls. Ito was unaffected by omega-3 PUFA treatment. Omega-3 PUFA treatment attenuated the action potential prolongation in VF+ myocytes, but did not return repolarization to control values. Conclusions: Omega-3 PUFAs do not confer anti-arrhythmic properties in the setting of healed myocardial infarction in a canine model of SCD. In canines previously resistant to ventricular fibrillation (VF−), omega-3 PUFA treatment prolonged the action potential in VF− myocytes, and may contribute to pro-arrhythmic responses.
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Affiliation(s)
- Ingrid M Bonilla
- College of Pharmacy, The Ohio State UniversityColumbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State UniversityColumbus, OH, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State UniversityColumbus, OH, USA
| | | | - Pedro Vargas-Pinto
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University Columbus, OH, USA
| | - Stephen H Baine
- College of Pharmacy, The Ohio State University Columbus, OH, USA
| | - Arun Sridhar
- College of Pharmacy, The Ohio State University Columbus, OH, USA
| | - Chun Li
- Division of Cardiology, Peking University People's Hospital Beijing, China
| | - George E Billman
- Department of Physiology and Cell Biology, The Ohio State UniversityColumbus, OH, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State UniversityColumbus, OH, USA
| | - Cynthia A Carnes
- College of Pharmacy, The Ohio State UniversityColumbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State UniversityColumbus, OH, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State UniversityColumbus, OH, USA
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60
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Singh S, Sahoo SK, Periasamy M. Sarcolipin. ENCYCLOPEDIA OF SIGNALING MOLECULES 2016:1-5. [DOI: 10.1007/978-1-4614-6438-9_101787-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 08/11/2016] [Indexed: 06/16/2023]
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61
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Shaikh SA, Sahoo SK, Periasamy M. Phospholamban and sarcolipin: Are they functionally redundant or distinct regulators of the Sarco(Endo)Plasmic Reticulum Calcium ATPase? J Mol Cell Cardiol 2015; 91:81-91. [PMID: 26743715 DOI: 10.1016/j.yjmcc.2015.12.030] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 12/10/2015] [Accepted: 12/29/2015] [Indexed: 10/22/2022]
Abstract
In muscle, the Sarco(Endo)plasmic Reticulum Calcium ATPase (SERCA) activity is regulated by two distinct proteins, PLB and SLN, which are highly conserved throughout vertebrate evolution. PLB is predominantly expressed in the cardiac muscle, while SLN is abundant in skeletal muscle. SLN is also found in the cardiac atria and to a lesser extent in the ventricle. PLB regulation of SERCA is central to cardiac function, both at rest and during extreme physiological demand. Compared to PLB, the physiological relevance of SLN remained a mystery until recently and some even thought it was redundant in function. Studies on SLN suggest that it is an uncoupler of the SERCA pump activity and can increase ATP hydrolysis resulting in heat production. Using genetically engineered mouse models for SLN and PLB, we showed that SLN, not PLB, is required for muscle-based thermogenesis. However, the mechanism of how SLN binding to SERCA results in uncoupling SERCA Ca(2+) transport from its ATPase activity remains unclear. In this review, we discuss recent advances in understanding how PLB and SLN differ in their interaction with SERCA. We will also explore whether structural differences in the cytosolic domain of PLB and SLN are the basis for their unique function and physiological roles in cardiac and skeletal muscle.
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Affiliation(s)
- Sana A Shaikh
- Center for Metabolic Origins of Disease, Cardiovascular Metabolism Program, Sanford Burnham Prebys Medical Discovery Institute, Lake Nona, FL. 6400 Sanger Road, Orlando, FL 32827, United States
| | - Sanjaya K Sahoo
- Center for Metabolic Origins of Disease, Cardiovascular Metabolism Program, Sanford Burnham Prebys Medical Discovery Institute, Lake Nona, FL. 6400 Sanger Road, Orlando, FL 32827, United States
| | - Muthu Periasamy
- Center for Metabolic Origins of Disease, Cardiovascular Metabolism Program, Sanford Burnham Prebys Medical Discovery Institute, Lake Nona, FL. 6400 Sanger Road, Orlando, FL 32827, United States.
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62
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Heijman J, Erfanian Abdoust P, Voigt N, Nattel S, Dobrev D. Computational models of atrial cellular electrophysiology and calcium handling, and their role in atrial fibrillation. J Physiol 2015; 594:537-53. [PMID: 26582329 DOI: 10.1113/jp271404] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/08/2015] [Indexed: 11/08/2022] Open
Abstract
The complexity of the heart makes an intuitive understanding of the relative contribution of ion channels, transporters and signalling pathways to cardiac electrophysiology challenging. Computational modelling of cardiac cellular electrophysiology has proven useful to integrate experimental findings, extrapolate results obtained in expression systems or animal models to other systems, test quantitatively ideas based on experimental data and provide novel hypotheses that are experimentally testable. While the bulk of computational modelling has traditionally been directed towards ventricular bioelectricity, increasing recognition of the clinical importance of atrial arrhythmias, particularly atrial fibrillation, has led to widespread efforts to apply computational approaches to understanding atrial electrical function. The increasing availability of detailed, atrial-specific experimental data has stimulated the development of novel computational models of atrial-cellular electrophysiology and Ca(2+) handling. To date, more than 300 studies have employed mathematical simulations to enhance our understanding of atrial electrophysiology, arrhythmogenesis and therapeutic responses. Future modelling studies are likely to move beyond current whole-cell models by incorporating new data on subcellular architecture, macromolecular protein complexes, and localized ion-channel regulation by signalling pathways. At the same time, more integrative multicellular models that take into account regional electrophysiological and Ca(2+) handling properties, mechano-electrical feedback and/or autonomic regulation will be needed to investigate the mechanisms governing atrial arrhythmias. A combined experimental and computational approach is expected to provide the more comprehensive understanding of atrial arrhythmogenesis that is required to develop improved diagnostic and therapeutic options. Here, we review this rapidly expanding area, with a particular focus on Ca(2+) handling, and provide ideas about potential future directions.
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Affiliation(s)
- Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands.,Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
| | - Pegah Erfanian Abdoust
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
| | - Niels Voigt
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
| | - Stanley Nattel
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany.,Department of Medicine, Montreal Heart Institute and Université de Montréal, Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
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63
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Maurya SK, Periasamy M. Sarcolipin is a novel regulator of muscle metabolism and obesity. Pharmacol Res 2015; 102:270-5. [PMID: 26521759 DOI: 10.1016/j.phrs.2015.10.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 10/13/2015] [Indexed: 02/07/2023]
Abstract
Obesity is increasing at an alarming rate, both in adults and adolescents, across the globe due to increased consumption of caloric rich diet. Obesity and its associated complications appear to be major contributing factors not only to diabetes/heart disease but also to cancer, and neurological diseases causing a huge burden on the health care system. To date, there are no effective treatments to reduce weight gain, other than caloric restriction and exercise which are often difficult to enforce. There are very few drugs available for treating obesity and those that are available only reduce obesity by ∼ 10%. Identifying mechanisms to increase energy expenditure, on top of the increase elicited by exercise, would be more beneficial to control weight gain. The purpose of this review is to highlight the role of sarcolipin (SLN), a regulator of SERCA pump, in muscle thermogenesis and metabolism. We will further discuss if enhancing SLN activity could be an effective mechanism to increase energy expenditure and control weight gain. We will also discuss the merits of adaptive thermogenesis in muscle and brown fat as potential mechanisms to increase energy expenditure during caloric overload. That said, there is still a great need for further research into the mechanism of diet induced thermogenesis and its relevance to overall metabolism and obesity.
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Affiliation(s)
- Santosh Kumar Maurya
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, FL, USA
| | - Muthu Periasamy
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, FL, USA.
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64
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Pant M, Bal NC, Periasamy M. Cold adaptation overrides developmental regulation of sarcolipin expression in mice skeletal muscle: SOS for muscle-based thermogenesis? ACTA ACUST UNITED AC 2015; 218:2321-5. [PMID: 26026037 DOI: 10.1242/jeb.119164] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 05/18/2015] [Indexed: 12/31/2022]
Abstract
Neonatal mice have a greater thermogenic need than adult mice and may require additional means of heat production, other than the established mechanism of brown adipose tissue (BAT). We and others recently discovered a novel mediator of skeletal muscle-based thermogenesis called sarcolipin (SLN) that acts by uncoupling sarcoendoplasmic reticulum Ca(2+)-ATPase (SERCA). In addition, we have shown that SLN expression is downregulated during neonatal development in rats. In this study we probed two questions: (1) is SLN expression developmentally regulated in neonatal mice?; and (2) if so, will cold adaptation override this? Our data show that SLN expression is higher during early neonatal stages and is gradually downregulated in fast twitch skeletal muscles. Interestingly, we demonstrate that cold acclimation of neonatal mice can prevent downregulation of SLN expression. This observation suggests that SLN-mediated thermogenesis can be recruited to a greater extent during extreme physiological need, in addition to BAT.
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Affiliation(s)
- Meghna Pant
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Naresh C Bal
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Muthu Periasamy
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA
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65
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Espinoza-Fonseca LM, Autry JM, Thomas DD. Sarcolipin and phospholamban inhibit the calcium pump by populating a similar metal ion-free intermediate state. Biochem Biophys Res Commun 2015; 463:37-41. [PMID: 25983321 DOI: 10.1016/j.bbrc.2015.05.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 05/06/2015] [Indexed: 12/31/2022]
Abstract
We have performed microsecond molecular dynamics (MD) simulations and protein pKa calculations of the muscle calcium pump (sarcoplasmic reticulum Ca(2+)-ATPase, SERCA) in complex with sarcolipin (SLN) to determine the mechanism by which SLN inhibits SERCA. SLN and its close analog phospholamban (PLN) are membrane proteins that regulate SERCA by inhibiting Ca(2+) transport in skeletal and cardiac muscle. Although SLN and PLB binding to SERCA have different functional outcomes on the coupling efficiency of SERCA, both proteins decrease the apparent Ca(2+) affinity of the pump, suggesting that SLN and PLB inhibit SERCA by using a similar mechanism. Recently, MD simulations showed that PLB inhibits SERCA by populating a metal ion-free, partially-protonated E1 state of the pump, E1· [Formula: see text] . X-ray crystallography studies at 40-80 mM Mg(2+) have proposed that SLN-bound SERCA populates E1·Mg(2+), an intermediate with Mg(2+) bound near transport site I. To test this proposed mode of SLN regulation, we performed a 0.5-μs MD simulation of E1·Mg(2+)-SLN in a solution containing 100 mM K(+) and 3 mM Mg(2+), with calculation of domain dynamics in the cytosolic headpiece and side-chain ionization and occupancy in the transport sites. We found that SLN increases the distance between residues E771 and D800, thereby rendering E1·Mg(2+) incapable of producing a competent Ca(2+) transport site I. Following removal of Mg(2+,) a 2-μs MD simulation of Mg(2+)-free SERCA-SLN showed that Mg(2+) does not re-bind to the transport sites, indicating that SERCA-SLN does not populate E1·Mg(2+) at physiological conditions. Instead, protein pKa calculations indicate that SLN stabilizes a metal ion-free SERCA state (E1· [Formula: see text] ) protonated at residue E771, but ionized at E309 and D800. We conclude that both SLN and PLB inhibit SERCA by populating a similar metal ion-free intermediate state. We propose that (i) this partially-protonated intermediate serves as the consensus mechanism for SERCA inhibition by other members of the SERCA regulatory subunit family including myoregulin and sarcolamban, and (ii) this consensus mechanism is utilized to regulate Ca(2+) transport in skeletal and cardiac muscle, with important implications for therapeutic approaches to muscle dystrophy and heart failure.
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Affiliation(s)
- L Michel Espinoza-Fonseca
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Joseph M Autry
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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66
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Sahoo SK, Shaikh SA, Sopariwala DH, Bal NC, Bruhn DS, Kopec W, Khandelia H, Periasamy M. The N Terminus of Sarcolipin Plays an Important Role in Uncoupling Sarco-endoplasmic Reticulum Ca2+-ATPase (SERCA) ATP Hydrolysis from Ca2+ Transport. J Biol Chem 2015; 290:14057-67. [PMID: 25882845 DOI: 10.1074/jbc.m115.636738] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Indexed: 01/13/2023] Open
Abstract
The sarcoendoplasmic reticulum Ca(2+)-ATPase (SERCA) is responsible for intracellular Ca(2+) homeostasis. SERCA activity in muscle can be regulated by phospholamban (PLB), an affinity modulator, and sarcolipin (SLN), an uncoupler. Although PLB gets dislodged from Ca(2+)-bound SERCA, SLN continues to bind SERCA throughout its kinetic cycle and promotes uncoupling of Ca(2+) transport from ATP hydrolysis. To determine the structural regions of SLN that mediate uncoupling of SERCA, we employed mutagenesis and generated chimeras of PLB and SLN. In this study we demonstrate that deletion of SLN N-terminal residues (2)ERSTQ leads to loss of the uncoupling function even though the truncated peptide can target and constitutively bind SERCA. Furthermore, molecular dynamics simulations of SLN and SERCA interaction showed a rearrangement of SERCA residues that is altered when the SLN N terminus is deleted. Interestingly, transfer of the PLB cytosolic domain to the SLN transmembrane (TM) and luminal tail causes the chimeric protein to lose SLN-like function. Further introduction of the PLB TM region into this chimera resulted in conversion to full PLB-like function. We also found that swapping PLB N and C termini with those from SLN caused the resulting chimera to acquire SLN-like function. Swapping the C terminus alone was not sufficient for this conversion. These results suggest that domains can be switched between SLN and PLB without losing the ability to regulate SERCA activity; however, the resulting chimeras acquire functions different from the parent molecules. Importantly, our studies highlight that the N termini of SLN and PLB influence their respective unique functions.
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Affiliation(s)
- Sanjaya K Sahoo
- the Sanford Burnham Medical Research Institute at Lake Nona, Orlando, Florida 32827
| | - Sana A Shaikh
- From the Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210
| | - Danesh H Sopariwala
- From the Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210
| | - Naresh C Bal
- From the Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210
| | - Dennis Skjøth Bruhn
- the MEMPHYS, Center for Biomembrane Physics, University of Southern Denmark, Odense M 5230, Denmark, and
| | - Wojciech Kopec
- the MEMPHYS, Center for Biomembrane Physics, University of Southern Denmark, Odense M 5230, Denmark, and
| | - Himanshu Khandelia
- the MEMPHYS, Center for Biomembrane Physics, University of Southern Denmark, Odense M 5230, Denmark, and
| | - Muthu Periasamy
- the Sanford Burnham Medical Research Institute at Lake Nona, Orlando, Florida 32827 From the Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210,
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Sopariwala DH, Pant M, Shaikh SA, Goonasekera SA, Molkentin JD, Weisleder N, Ma J, Pan Z, Periasamy M. Sarcolipin overexpression improves muscle energetics and reduces fatigue. J Appl Physiol (1985) 2015; 118:1050-8. [PMID: 25701006 DOI: 10.1152/japplphysiol.01066.2014] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/17/2015] [Indexed: 12/21/2022] Open
Abstract
Sarcolipin (SLN) is a regulator of sarcoendoplasmic reticulum calcium ATPase in skeletal muscle. Recent studies using SLN-null mice have identified SLN as a key player in muscle thermogenesis and metabolism. In this study, we exploited a SLN overexpression (Sln(OE)) mouse model to determine whether increased SLN level affected muscle contractile properties, exercise capacity/fatigue, and metabolic rate in whole animals and isolated muscle. We found that Sln(OE) mice are more resistant to fatigue and can run significantly longer distances than wild-type (WT). Studies with isolated extensor digitorum longus (EDL) muscles showed that Sln(OE) EDL produced higher twitch force than WT. The force-frequency curves were not different between WT and Sln(OE) EDLs, but at lower frequencies the pyruvate-induced potentiation of force was significantly higher in Sln(OE) EDL. SLN overexpression did not alter the twitch and force-frequency curve in isolated soleus muscle. However, during a 10-min fatigue protocol, both EDL and soleus from Sln(OE) mice fatigued significantly less than WT muscles. Interestingly, Sln(OE) muscles showed higher carnitine palmitoyl transferase-1 protein expression, which could enhance fatty acid metabolism. In addition, lactate dehydrogenase expression was higher in Sln(OE) EDL, suggesting increased glycolytic capacity. We also found an increase in store-operated calcium entry (SOCE) in isolated flexor digitorum brevis fibers of Sln(OE) compared with WT mice. These data allow us to conclude that increased SLN expression improves skeletal muscle performance during prolonged muscle activity by increasing SOCE and muscle energetics.
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Affiliation(s)
- Danesh H Sopariwala
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio
| | - Meghna Pant
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio
| | - Sana A Shaikh
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio
| | | | - Jeffery D Molkentin
- Department of Pediatrics, University of Cincinnati, Cincinnati, Ohio; Howard Hughes Medical Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Noah Weisleder
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio
| | - Jianjie Ma
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Zui Pan
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Muthu Periasamy
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio; Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio;
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Shanmugam M, Li D, Gao S, Fefelova N, Shah V, Voit A, Pachon R, Yehia G, Xie LH, Babu GJ. Cardiac specific expression of threonine 5 to alanine mutant sarcolipin results in structural remodeling and diastolic dysfunction. PLoS One 2015; 10:e0115822. [PMID: 25671318 PMCID: PMC4324845 DOI: 10.1371/journal.pone.0115822] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 12/02/2014] [Indexed: 12/23/2022] Open
Abstract
The functional importance of threonine 5 (T5) in modulating the activity of sarcolipin (SLN), a key regulator of sarco/endoplasmic reticulum (SR) Ca2+ ATPase (SERCA) pump was studied using a transgenic mouse model with cardiac specific expression of threonine 5 to alanine mutant SLN (SLNT5A). In these transgenic mice, the SLNT5A protein replaces the endogenous SLN in atria, while maintaining the total SLN content. The cardiac specific expression of SLNT5A results in severe cardiac structural remodeling accompanied by bi-atrial enlargement. Biochemical analyses reveal a selective downregulation of SR Ca2+ handling proteins and a reduced SR Ca2+ uptake both in atria and in the ventricles. Optical mapping analysis shows slower action potential propagation in the transgenic mice atria. Doppler echocardiography and hemodynamic measurements demonstrate a reduced atrial contractility and an impaired diastolic function. Together, these findings suggest that threonine 5 plays an important role in modulating SLN function in the heart. Furthermore, our studies suggest that alteration in SLN function can cause abnormal Ca2+ handling and subsequent cardiac remodeling and dysfunction.
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Affiliation(s)
- Mayilvahanan Shanmugam
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Dan Li
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Shumin Gao
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Nadezhda Fefelova
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Vikas Shah
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Antanina Voit
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Ronald Pachon
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Ghassan Yehia
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Gopal J. Babu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
- * E-mail:
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69
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The effects of sarcolipin over-expression in mouse skeletal muscle on metabolic activity. Arch Biochem Biophys 2015; 569:26-31. [PMID: 25660043 PMCID: PMC4362768 DOI: 10.1016/j.abb.2015.01.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/27/2015] [Accepted: 01/29/2015] [Indexed: 11/24/2022]
Abstract
Sarcolipin is insufficient to affect thermogenic activity of SERCA in mouse muscle. The ratio of SLN to SERCA in total limb skeletal muscle is <0.0015 mol/mol. Knocking out this SLN in mice would have a small effect on SERCA function. Overexpressing SLN in transgenic mice only resulted in 0.037 mol SLN/mol SERCA. SLN+/+ mice showed no evidence of an increase in thermogenesis.
Studies in sarcolipin knockout mice have led to the suggestion that skeletal muscle sarcolipin plays a role in thermogenesis. The mechanism proposed is uncoupling of the sarcoplasmic reticulum calcium pump. However, in other work sarcolipin was not detected in mouse skeletal tissue. We have therefore measured sarcolipin levels in mouse skeletal muscle using semi-quantitative western blotting and synthetic mouse sarcolipin. Sarcolipin levels were so low that it is unlikely that knocking out sarcolipin would have a measurable effect on thermogenesis by SERCA. In addition, overexpression of neither wild type nor FLAG-tagged variants of mouse sarcolipin in transgenic mice had any major significant effects on body mass, energy expenditure, even when mice were fed on a high fat diet.
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Stammers AN, Susser SE, Hamm NC, Hlynsky MW, Kimber DE, Kehler DS, Duhamel TA. The regulation of sarco(endo)plasmic reticulum calcium-ATPases (SERCA). Can J Physiol Pharmacol 2015; 93:843-54. [PMID: 25730320 DOI: 10.1139/cjpp-2014-0463] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The sarco(endo)plasmic reticulum calcium ATPase (SERCA) is responsible for transporting calcium (Ca(2+)) from the cytosol into the lumen of the sarcoplasmic reticulum (SR) following muscular contraction. The Ca(2+) sequestering activity of SERCA facilitates muscular relaxation in both cardiac and skeletal muscle. There are more than 10 distinct isoforms of SERCA expressed in different tissues. SERCA2a is the primary isoform expressed in cardiac tissue, whereas SERCA1a is the predominant isoform expressed in fast-twitch skeletal muscle. The Ca(2+) sequestering activity of SERCA is regulated at the level of protein content and is further modified by the endogenous proteins phospholamban (PLN) and sarcolipin (SLN). Additionally, several novel mechanisms, including post-translational modifications and microRNAs (miRNAs) are emerging as integral regulators of Ca(2+) transport activity. These regulatory mechanisms are clinically relevant, as dysregulated SERCA function has been implicated in the pathology of several disease states, including heart failure. Currently, several clinical trials are underway that utilize novel therapeutic approaches to restore SERCA2a activity in humans. The purpose of this review is to examine the regulatory mechanisms of the SERCA pump, with a particular emphasis on the influence of exercise in preventing the pathological conditions associated with impaired SERCA function.
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Affiliation(s)
- Andrew N Stammers
- a Health, Leisure & Human Performance Research Institute, Faculty of Kinesiology & Recreation Management, University of Manitoba.,b Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre
| | - Shanel E Susser
- b Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre.,c Department of Physiology, Faculty of Health Sciences, University of Manitoba
| | - Naomi C Hamm
- a Health, Leisure & Human Performance Research Institute, Faculty of Kinesiology & Recreation Management, University of Manitoba.,b Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre
| | - Michael W Hlynsky
- a Health, Leisure & Human Performance Research Institute, Faculty of Kinesiology & Recreation Management, University of Manitoba.,b Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre
| | - Dustin E Kimber
- a Health, Leisure & Human Performance Research Institute, Faculty of Kinesiology & Recreation Management, University of Manitoba.,b Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre
| | - D Scott Kehler
- a Health, Leisure & Human Performance Research Institute, Faculty of Kinesiology & Recreation Management, University of Manitoba.,b Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre
| | - Todd A Duhamel
- a Health, Leisure & Human Performance Research Institute, Faculty of Kinesiology & Recreation Management, University of Manitoba.,b Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre.,c Department of Physiology, Faculty of Health Sciences, University of Manitoba
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71
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The neonatal sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA1b): a neglected pump in scope. Pflugers Arch 2014; 467:1395-1401. [DOI: 10.1007/s00424-014-1671-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 12/04/2014] [Accepted: 12/08/2014] [Indexed: 01/03/2023]
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Kósa M, Brinyiczki K, van Damme P, Goemans N, Hancsák K, Mendler L, Zádor E. The neonatal sarcoplasmic reticulum Ca2+-ATPase gives a clue to development and pathology in human muscles. J Muscle Res Cell Motil 2014; 36:195-203. [PMID: 25487304 DOI: 10.1007/s10974-014-9403-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 12/03/2014] [Indexed: 01/07/2023]
Abstract
The sarcoplasmic/endoplasmic reticulum calcium ATPase 1 (SERCA1) has two muscle specific splice isoforms; SERCA1a in fast-type adult and SERCA1b in neonatal and regenerating skeletal muscles. At the protein level the only difference between these two isoforms is that SERCA1a has C-terminal glycine while SERCA1b has an octapeptide tail instead. This makes the generation of a SERCA1a specific antibody not feasible. The switch between the two isoforms is a hallmark of differentiation so we describe here a method based on the signal ratios of the SERCA1b specific and pan SERCA1 antibodies to estimate the SERCA1b/SERCA1a dominance on immunoblot of human muscles. Using this method we showed that unlike in mouse and rat, SERCA1b was only expressed in pre-matured infant leg and arm muscles; it was replaced by SERCA1a in more matured neonatal muscles and was completely absent in human foetal and neonatal diaphragms. Interestingly, only SERCA1a and no SERCA1b were detected in muscles of 7-12 years old boys with Duchenne, a degenerative-regenerative muscular dystrophy. However, in adult patients with myotonic dystrophy type 2 (DM2), the SERCA1b dominated over SERCA1a. Thus the human SERCA1b has a different expression pattern from that of rodents and it is associated with DM2.
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Affiliation(s)
- Magdolna Kósa
- Department of Biochemistry, Faculty of General Medicine, University of Szeged, Dóm tér 9, H-6720, Szeged, Hungary
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Rowland LA, Bal NC, Periasamy M. The role of skeletal-muscle-based thermogenic mechanisms in vertebrate endothermy. Biol Rev Camb Philos Soc 2014; 90:1279-97. [PMID: 25424279 DOI: 10.1111/brv.12157] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 10/03/2014] [Accepted: 10/14/2014] [Indexed: 12/17/2022]
Abstract
Thermogenesis is one of the most important homeostatic mechanisms that evolved during vertebrate evolution. Despite its importance for the survival of the organism, the mechanistic details behind various thermogenic processes remain incompletely understood. Although heat production from muscle has long been recognized as a thermogenic mechanism, whether muscle can produce heat independently of contraction remains controversial. Studies in birds and mammals suggest that skeletal muscle can be an important site of non-shivering thermogenesis (NST) and can be recruited during cold adaptation, although unequivocal evidence is lacking. Much research on thermogenesis during the last two decades has been focused on brown adipose tissue (BAT). These studies clearly implicate BAT as an important site of NST in mammals, in particular in newborns and rodents. However, BAT is either absent, as in birds and pigs, or is only a minor component, as in adult large mammals including humans, bringing into question the BAT-centric view of thermogenesis. This review focuses on the evolution and emergence of various thermogenic mechanisms in vertebrates from fish to man. A careful analysis of the existing data reveals that muscle was the earliest facultative thermogenic organ to emerge in vertebrates, long before the appearance of BAT in eutherian mammals. Additionally, these studies suggest that muscle-based thermogenesis is the dominant mechanism of heat production in many species including birds, marsupials, and certain mammals where BAT-mediated thermogenesis is absent or limited. We discuss the relevance of our recent findings showing that uncoupling of sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) by sarcolipin (SLN), resulting in futile cycling and increased heat production, could be the basis for NST in skeletal muscle. The overall goal of this review is to highlight the role of skeletal muscle as a thermogenic organ and provide a balanced view of thermogenesis in vertebrates.
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Affiliation(s)
- Leslie A Rowland
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, U.S.A
| | - Naresh C Bal
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, U.S.A
| | - Muthu Periasamy
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, U.S.A
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Montigny C, Decottignies P, Le Maréchal P, Capy P, Bublitz M, Olesen C, Møller JV, Nissen P, le Maire M. S-palmitoylation and s-oleoylation of rabbit and pig sarcolipin. J Biol Chem 2014; 289:33850-61. [PMID: 25301946 DOI: 10.1074/jbc.m114.590307] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sarcolipin (SLN) is a regulatory peptide present in sarcoplasmic reticulum (SR) from skeletal muscle of animals. We find that native rabbit SLN is modified by a fatty acid anchor on Cys-9 with a palmitic acid in about 60% and, surprisingly, an oleic acid in the remaining 40%. SLN used for co-crystallization with SERCA1a (Winther, A. M., Bublitz, M., Karlsen, J. L., Moller, J. V., Hansen, J. B., Nissen, P., and Buch-Pedersen, M. J. (2013) Nature 495, 265-2691; Ref. 1) is also palmitoylated/oleoylated, but is not visible in crystal structures, probably due to disorder. Treatment with 1 m hydroxylamine for 1 h removes the fatty acids from a majority of the SLN pool. This treatment did not modify the SERCA1a affinity for Ca(2+) but increased the Ca(2+)-dependent ATPase activity of SR membranes indicating that the S-acylation of SLN or of other proteins is required for this effect on SERCA1a. Pig SLN is also fully palmitoylated/oleoylated on its Cys-9 residue, but in a reverse ratio of about 40/60. An alignment of 67 SLN sequences from the protein databases shows that 19 of them contain a cysteine and the rest a phenylalanine at position 9. Based on a cladogram, we postulate that the mutation from phenylalanine to cysteine in some species is the result of an evolutionary convergence. We suggest that, besides phosphorylation, S-acylation/deacylation also regulates SLN activity.
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Affiliation(s)
- Cédric Montigny
- From the Laboratoire des Protéines Membranaires, UMR 8221, Commissariat à l'Energie Atomique (CEA), Université Paris-Sud and Centre National de la Recherche Scientifique (CNRS), F91191, Gif-sur-Yvette, France
| | - Paulette Decottignies
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, CNRS UMR 8619, Université Paris-Sud, F91400, Orsay, France
| | - Pierre Le Maréchal
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, CNRS UMR 8619, Université Paris-Sud, F91400, Orsay, France
| | - Pierre Capy
- Laboratoire Evolution, Génomes et Spéciation, CNRS UPR 9034, Centre de Recherche de Gif and Université Paris-Sud, F91190, Gif-sur-Yvette, France
| | - Maike Bublitz
- Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, and
| | - Claus Olesen
- Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, and Department of Biomedicine, Aarhus University, 8000, Aarhus, Denmark
| | - Jesper Vuust Møller
- Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, and
| | - Poul Nissen
- Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, and
| | - Marc le Maire
- From the Laboratoire des Protéines Membranaires, UMR 8221, Commissariat à l'Energie Atomique (CEA), Université Paris-Sud and Centre National de la Recherche Scientifique (CNRS), F91191, Gif-sur-Yvette, France,
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Holemans T, Vandecaetsbeek I, Wuytack F, Vangheluwe P. Measuring Ca2+-dependent Ca2+-uptake activity in the mouse heart. Cold Spring Harb Protoc 2014; 2014:876-86. [PMID: 25086013 DOI: 10.1101/pdb.prot076893] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The apparent Ca(2+) affinity of the isoforms of the sarco/endoplasmic reticulum Ca(2+) ATPase SERCA2 is controlled primarily by two proteins, phospholamban (PLB) and sarcolipin (SLN). The rate of ATP-driven Ca(2+) uptake into sarcoplasmic reticulum (SR)-derived vesicles can be monitored by a technique in which the net uptake of (45)Ca(2+) in the form of an intravesicular calcium oxalate precipitate is recorded. Here, we present details of a modification of such a protocol for determining the apparent Ca(2+) affinity of the Ca(2+) pump, and its control by various regulators, in crude homogenates of mouse heart.
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Affiliation(s)
- Tine Holemans
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, B3000 Leuven, Belgium
| | - Ilse Vandecaetsbeek
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, B3000 Leuven, Belgium
| | - Frank Wuytack
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, B3000 Leuven, Belgium
| | - Peter Vangheluwe
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, B3000 Leuven, Belgium
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Josowitz R, Lu J, Falce C, D’Souza SL, Wu M, Cohen N, Dubois NC, Zhao Y, Sobie EA, Fishman GI, Gelb BD. Identification and purification of human induced pluripotent stem cell-derived atrial-like cardiomyocytes based on sarcolipin expression. PLoS One 2014; 9:e101316. [PMID: 25010565 PMCID: PMC4092021 DOI: 10.1371/journal.pone.0101316] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 06/05/2014] [Indexed: 12/16/2022] Open
Abstract
The use of human stem cell-derived cardiomyocytes to study atrial biology and disease has been restricted by the lack of a reliable method for stem cell-derived atrial cell labeling and purification. The goal of this study was to generate an atrial-specific reporter construct to identify and purify human stem cell-derived atrial-like cardiomyocytes. We have created a bacterial artificial chromosome (BAC) reporter construct in which fluorescence is driven by expression of the atrial-specific gene sarcolipin (SLN). When purified using flow cytometry, cells with high fluorescence specifically express atrial genes and display functional calcium handling and electrophysiological properties consistent with atrial cardiomyocytes. Our data indicate that SLN can be used as a marker to successfully monitor and isolate hiPSC-derived atrial-like cardiomyocytes. These purified cells may find many applications, including in the study of atrial-specific pathologies and chamber-specific lineage development.
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Affiliation(s)
- Rebecca Josowitz
- The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Jia Lu
- The Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, United States of America
| | - Christine Falce
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Sunita L. D’Souza
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Meng Wu
- The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Ninette Cohen
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Nicole C. Dubois
- The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Yong Zhao
- The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Eric A. Sobie
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Glenn I. Fishman
- The Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, United States of America
- Department of Medicine, New York University School of Medicine, New York, New York, United States of America
| | - Bruce D. Gelb
- The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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Iruretagoyena J, Davis W, Bird C, Olsen J, Radue R, Teo Broman A, Kendziorski C, Splinter BonDurant S, Golos T, Bird I, Shah D. Metabolic gene profile in early human fetal heart development. ACTA ACUST UNITED AC 2014; 20:690-700. [PMID: 24674993 DOI: 10.1093/molehr/gau026] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The primitive cardiac tube starts beating 6-8 weeks post fertilization in the developing embryo. In order to describe normal cardiac development during late first and early second trimester in human fetuses this study used microarray and pathways analysis and created a corresponding 'normal' database. Fourteen fetal hearts from human fetuses between 10 and 18 weeks of gestational age (GA) were prospectively collected at the time of elective termination of pregnancy. RNA from recovered tissues was used for transcriptome analysis with Affymetrix 1.0 ST microarray chip. From the amassed data we investigated differences in cardiac development within the 10-18 GA period dividing the sample by GA in three groups: 10-12 (H1), 13-15 (H2) and 16-18 (H3) weeks. A fold change of 2 or above adjusted for a false discovery rate of 5% was used as initial cutoff to determine differential gene expression for individual genes. Test for enrichment to identify functional groups was carried out using the Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Array analysis correctly identified the cardiac specific genes, and transcripts reported to be differentially expressed were confirmed by qRT-PCR. Single transcript and Ontology analysis showed first trimester heart expression of myosin-related genes to be up-regulated >5-fold compared with second trimester heart. In contrast the second trimester hearts showed further gestation-related increases in many genes involved in energy production and cardiac remodeling. In conclusion, fetal heart development during the first trimester was dominated by heart-specific genes coding for myocardial development and differentiation. During the second trimester, transcripts related to energy generation and cardiomyocyte communication for contractile coordination/proliferation were more dominant. Transcripts related to fatty acid metabolism can be seen as early as 10 weeks and clearly increase as the heart matures. Retinol receptor and gamma-aminobutyric acid (GABA) receptor transcripts were detected, and have not been described previously in human fetal heart during this period. For the first time global gene expression of heart has been described in human samples to create a database of normal development to understand and compare with known abnormal fetal heart development.
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78
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Lamboley CR, Murphy RM, McKenna MJ, Lamb GD. Sarcoplasmic reticulum Ca2+ uptake and leak properties, and SERCA isoform expression, in type I and type II fibres of human skeletal muscle. J Physiol 2014; 592:1381-95. [PMID: 24469076 DOI: 10.1113/jphysiol.2013.269373] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Ca(2+) uptake properties of the sarcoplasmic reticulum (SR) were compared between type I and type II fibres of vastus lateralis muscle of young healthy adults. Individual mechanically skinned muscle fibres were exposed to solutions with the free [Ca(2+)] heavily buffered in the pCa range (-log10[Ca(2+)]) 7.3-6.0 for set times and the amount of net SR Ca(2+) accumulation determined from the force response elicited upon emptying the SR of all Ca(2+). Western blotting was used to determine fibre type and the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) isoform present in every fibre examined. Type I fibres contained only SERCA2 and displayed half-maximal Ca(2+) uptake rate at ∼pCa 6.8, whereas type II fibres contained only SERCA1 and displayed half-maximal Ca(2+) uptake rate at ∼pCa 6.6. Maximal Ca(2+) uptake rate was ∼0.18 and ∼0.21 mmol Ca(2+) (l fibre)(-1) s(-1) in type I and type II fibres, respectively, in good accord with previously measured SR ATPase activity. Increasing free [Mg(2+)] from 1 to 3 mM had no significant effect on the net Ca(2+) uptake rate at pCa 6.0, indicating that there was little or no calcium-induced calcium release occurring through the Ca(2+) release channels during uptake in either fibre type. Ca(2+) leakage from the SR at pCa 8.5, which is thought to occur at least in part through the SERCA, was ∼2-fold lower in type II fibres than in type I fibres, and was little affected by the presence of ADP, in marked contrast to the larger SR Ca(2+) leak observed in rat muscle fibres under the same conditions. The higher affinity of Ca(2+) uptake in the type I human fibres can account for the higher relative level of SR Ca(2+) loading observed in type I compared to type II fibres, and the SR Ca(2+) leakage characteristics of the human fibres suggest that the SERCAs are regulated differently from those in rat and contribute comparatively less to resting metabolic rate.
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Affiliation(s)
- C R Lamboley
- Department of Zoology, La Trobe University, Melbourne, Victoria 3086, Australia.
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79
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Sikkel MB, Hayward C, MacLeod KT, Harding SE, Lyon AR. SERCA2a gene therapy in heart failure: an anti-arrhythmic positive inotrope. Br J Pharmacol 2014; 171:38-54. [PMID: 24138023 PMCID: PMC3874695 DOI: 10.1111/bph.12472] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 09/16/2013] [Accepted: 09/24/2013] [Indexed: 01/14/2023] Open
Abstract
Therapeutic options that directly enhance cardiomyocyte contractility in chronic heart failure (HF) therapy are currently limited and do not improve prognosis. In fact, most positive inotropic agents, such as β-adrenoreceptor agonists and PDE inhibitors, which have been assessed in HF patients, cause increased mortality as a result of arrhythmia and sudden cardiac death. Cardiac sarcoplasmic reticulum Ca(2)(+) -ATPase2a (SERCA2a) is a key protein involved in sequestration of Ca(2)(+) into the sarcoplasmic reticulum (SR) during diastole. There is a reduction of SERCA2a protein level and function in HF, which has been successfully targeted via viral transfection of the SERCA2a gene into cardiac tissue in vivo. This has enhanced cardiac contractility and reduced mortality in several preclinical models of HF. Theoretical concerns have been raised regarding the possibility of arrhythmogenic adverse effects of SERCA2a gene therapy due to enhanced SR Ca(2)(+) load and induction of SR Ca(2)(+) leak as a result. Contrary to these concerns, SERCA2a gene therapy in a wide variety of preclinical models, including acute ischaemia/reperfusion, chronic pressure overload and chronic myocardial infarction, has resulted in a reduction in ventricular arrhythmias. The potential mechanisms for this unexpected beneficial effect, as well as mechanisms of enhancement of cardiac contractile function, are reviewed in this article.
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Affiliation(s)
- Markus B Sikkel
- Myocardial Function Section, National Heart and Lung Institute, Imperial CollegeLondon, UK
| | - Carl Hayward
- Myocardial Function Section, National Heart and Lung Institute, Imperial CollegeLondon, UK
- NIHR Cardiovascular Biomedical Research Unit, Royal Brompton HospitalLondon, UK
| | - Kenneth T MacLeod
- Myocardial Function Section, National Heart and Lung Institute, Imperial CollegeLondon, UK
| | - Sian E Harding
- Myocardial Function Section, National Heart and Lung Institute, Imperial CollegeLondon, UK
| | - Alexander R Lyon
- Myocardial Function Section, National Heart and Lung Institute, Imperial CollegeLondon, UK
- NIHR Cardiovascular Biomedical Research Unit, Royal Brompton HospitalLondon, UK
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80
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Fajardo VA, Bombardier E, Vigna C, Devji T, Bloemberg D, Gamu D, Gramolini AO, Quadrilatero J, Tupling AR. Co-expression of SERCA isoforms, phospholamban and sarcolipin in human skeletal muscle fibers. PLoS One 2013; 8:e84304. [PMID: 24358354 PMCID: PMC3865254 DOI: 10.1371/journal.pone.0084304] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 11/13/2013] [Indexed: 01/22/2023] Open
Abstract
Sarcolipin (SLN) and phospholamban (PLN) inhibit the activity of sarco(endo)plasmic reticulum Ca2+-ATPases (SERCAs) by reducing their apparent affinity for Ca2+. A ternary complex between SLN, PLN, and SERCAs results in super-inhibition of SERCA activity. Analysis of skeletal muscle homogenate has limited our current understanding of whether SLN and PLN regulate SERCA1a, SERCA2a, or both in skeletal muscle and whether SLN and PLN are co-expressed in skeletal muscle fibers. Biopsies from human vastus lateralis were analyzed through single fiber Western blotting and immunohisto/fluorescence staining to circumvent this limitation. With a newly generated SLN antibody, we report for the first time that SLN protein is present in human skeletal muscle. Addition of the SLN antibody (50 µg) to vastus lateralis homogenates increased the apparent Ca2+ affinity of SERCA (KCa, pCa units) (-Ab, 5.85 ± 0.02 vs. +Ab, 5.95 ± 0.02) and maximal SERCA activity (μmol/g protein/min) (-Ab, 122 ± 6.4 vs. +Ab, 159 ± 11) demonstrating a functional interaction between SLN and SERCAs in human vastus lateralis. Specifically, our results suggest that although SLN and PLN may preferentially regulate SERCA1a, and SERCA2a, respectively, physiologically they both may regulate either SERCA isoform. Furthermore, we show that SLN and PLN co-immunoprecipitate in human vastus lateralis homogenate and are simultaneously expressed in 81% of the fibers analyzed with Western blotting which implies that super-inhibition of SERCA may exist in human skeletal muscle. Finally, we demonstrate unequivocally that mouse soleus contains PLN protein suggesting that super-inhibition of SERCA may also be important physiologically in rodent skeletal muscle.
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Affiliation(s)
- Val A. Fajardo
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Eric Bombardier
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Chris Vigna
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Tahira Devji
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Darin Bloemberg
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Daniel Gamu
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | | | - Joe Quadrilatero
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - A. Russell Tupling
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
- * E-mail:
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81
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Zheng J, Yancey DM, Ahmed MI, Wei CC, Powell PC, Shanmugam M, Gupta H, Lloyd SG, McGiffin DC, Schiros CG, Denney TS, Babu GJ, Dell'Italia LJ. Increased sarcolipin expression and adrenergic drive in humans with preserved left ventricular ejection fraction and chronic isolated mitral regurgitation. Circ Heart Fail 2013; 7:194-202. [PMID: 24297688 DOI: 10.1161/circheartfailure.113.000519] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND There is currently no therapy proven to attenuate left ventricular (LV) dilatation and dysfunction in volume overload induced by isolated mitral regurgitation (MR). To better understand molecular signatures underlying isolated MR, we performed LV gene expression analyses and overlaid regulated genes into ingenuity pathway analysis in patients with isolated MR. METHODS AND RESULTS Gene arrays from LV tissue of 35 patients, taken at the time of surgical repair for isolated MR, were compared with 13 normal controls. Cine-MRI was performed in 31 patients before surgery to measure LV function and volume from serial short-axis summation. LV end-diastolic volume was 2-fold (P=0.005) higher in MR patients than in normal controls, and LV ejection fraction was 64±7% (50%-79%) in MR patients. Ingenuity pathway analysis identified significant activation of pathways involved in β-adrenergic, cAMP, and G-protein-coupled signaling, whereas there was downregulation of pathways associated with complement activation and acute phase response. SERCA2a and phospholamban protein were unchanged in MR versus control left ventricles. However, mRNA and protein levels of the sarcoplasmic reticulum Ca2+ ATPase (SERCA) regulatory protein sarcolipin, which is predominantly expressed in normal atria, were increased 12- and 6-fold, respectively. Immunofluorescence analysis confirmed the absence of sarcolipin in normal left ventricles and its marked upregulation in MR left ventricles. CONCLUSIONS These results demonstrate alterations in multiple pathways associated with β-adrenergic signaling and sarcolipin in the left ventricles of patients with isolated MR and LV ejection fraction>50%, suggesting a beneficial role for β-adrenergic blockade in isolated MR.
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82
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Differential effects of the peroxynitrite donor, SIN-1, on atrial and ventricular myocyte electrophysiology. J Cardiovasc Pharmacol 2013; 61:401-7. [PMID: 23364607 DOI: 10.1097/fjc.0b013e31828748ca] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Oxidative stress has been implicated in the pathogenesis of heart failure and atrial fibrillation and can result in increased peroxynitrite production in the myocardium. Atrial and ventricular canine cardiac myocytes were superfused with 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1), a peroxynitrite donor, to evaluate the acute electrophysiologic effects of peroxynitrite. Perforated whole-cell patch clamp techniques were used to record action potentials. SIN-1 (200 µM) increased the action potential duration (APD) in atrial and ventricular myocytes; however, in the atria, APD prolongation was rate independent, whereas in the ventricle APD, prolongation was rate dependent. In addition to prolongation of the action potential, beat-to-beat variability of repolarization was significantly increased in ventricular but not in atrial myocytes. We examined the contribution of intracellular calcium cycling to the effects of SIN-1 by treating myocytes with the SERCA blocker, thapsigargin (5-10 µM). Inhibition of calcium cycling prevented APD prolongation in the atrial and ventricular myocytes, and prevented the SIN-1-induced increase in ventricular beat-to-beat APD variability. Collectively, these data demonstrate that peroxynitrite affects atrial and ventricular electrophysiology differentially. A detailed understanding of oxidative modulation of electrophysiology in specific chambers is critical to optimize therapeutic approaches for cardiac diseases.
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83
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Gladden JD, Zelickson BR, Guichard JL, Ahmed MI, Yancey DM, Ballinger S, Shanmugam M, Babu GJ, Johnson MS, Darley-Usmar V, Dell'Italia LJ. Xanthine oxidase inhibition preserves left ventricular systolic but not diastolic function in cardiac volume overload. Am J Physiol Heart Circ Physiol 2013; 305:H1440-50. [PMID: 24014679 DOI: 10.1152/ajpheart.00007.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Xanthine oxidase (XO) is increased in human and rat left ventricular (LV) myocytes with volume overload (VO) of mitral regurgitation and aortocaval fistula (ACF). In the setting of increased ATP demand, XO-mediated ROS can decrease mitochondrial respiration and contractile function. Thus, we tested the hypothesis that XO inhibition improves cardiomyocyte bioenergetics and LV function in chronic ACF in the rat. Sprague-Dawley rats were randomized to either sham or ACF ± allopurinol (100 mg·kg(-1)·day(-1), n ≥7 rats/group). Echocardiography at 8 wk demonstrated a similar 37% increase in LV end-diastolic dimension (P < 0.001), a twofold increase in LV end-diastolic pressure/wall stress (P < 0.05), and a twofold increase in lung weight (P < 0.05) in treated and untreated ACF groups versus the sham group. LV ejection fraction, velocity of circumferential shortening, maximal systolic elastance, and contractile efficiency were significantly depressed in ACF and significantly improved in ACF + allopurinol rats, all of which occurred in the absence of changes in the maximum O2 consumption rate measured in isolated cardiomyocytes using the extracellular flux analyzer. However, the improvement in contractile function is not paralleled by any attenuation in LV dilatation, LV end-diastolic pressure/wall stress, and lung weight. In conclusion, allopurinol improves LV contractile function and efficiency possibly by diminishing the known XO-mediated ROS effects on myofilament Ca(2+) sensitivity. However, LV remodeling and diastolic properties are not improved, which may explain the failure of XO inhibition to improve symptoms and hospitalizations in patients with severe heart failure.
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Affiliation(s)
- James D Gladden
- University of Alabama at Birmingham (UABComprehensive Cardiovascular Center, UAB Birmingham, Alabama
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84
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Mayyas F, Alzoubi KH, Van Wagoner DR. Impact of aldosterone antagonists on the substrate for atrial fibrillation: aldosterone promotes oxidative stress and atrial structural/electrical remodeling. Int J Cardiol 2013; 168:5135-42. [PMID: 23993726 DOI: 10.1016/j.ijcard.2013.08.022] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 08/03/2013] [Indexed: 12/31/2022]
Abstract
Atrial fibrillation (AF), the most common cardiac arrhythmia, is an electrocardiographic description of a condition with multiple and complex underlying mechanisms. Oxidative stress is an important driver of structural remodeling that creates a substrate for AF. Oxidant radicals may promote increase of atrial oxidative damage, electrical and structural remodeling, and atrial inflammation. AF and other cardiovascular morbidities activate angiotensin (Ang-II)-dependent and independent cascades. A key component of the renin-angiotensin-aldosterone system (RAAS) is the mineralocorticoid aldosterone. Recent studies provide evidence of myocardial aldosterone synthesis. Aldosterone promotes cardiac oxidative stress, inflammation and structural/electrical remodeling via multiple mechanisms. In HF patients, aldosterone production is enhanced. In patients and in experimental HF and AF models, aldosterone receptor antagonists have favorable influences on cardiac remodeling and oxidative stress. Therapeutic approaches that seek to reduce AF burden by modulating the aldosterone system are likely beneficial but underutilized.
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Affiliation(s)
- Fadia Mayyas
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Jordan.
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85
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Wu SP, Cheng CM, Lanz RB, Wang T, Respress JL, Ather S, Chen W, Tsai SJ, Wehrens XHT, Tsai MJ, Tsai SY. Atrial identity is determined by a COUP-TFII regulatory network. Dev Cell 2013; 25:417-26. [PMID: 23725765 DOI: 10.1016/j.devcel.2013.04.017] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 04/11/2013] [Accepted: 04/29/2013] [Indexed: 11/29/2022]
Abstract
Atria and ventricles exhibit distinct molecular profiles that produce structural and functional differences between the two cardiac compartments. However, the factors that determine these differences remain largely undefined. Cardiomyocyte-specific COUP-TFII ablation produces ventricularized atria that exhibit ventricle-like action potentials, increased cardiomyocyte size, and development of extensive T tubules. Changes in atrial characteristics are accompanied by alterations of 2,584 genes, of which 81% were differentially expressed between atria and ventricles, suggesting that a major function of myocardial COUP-TFII is to determine atrial identity. Chromatin immunoprecipitation assays using E13.5 atria identified classic atrial-ventricular identity genes Tbx5, Hey2, Irx4, MLC2v, MLC2a, and MLC1a, among many other cardiac genes, as potential COUP-TFII direct targets. Collectively, our results reveal that COUP-TFII confers atrial identity through direct binding and by modulating expression of a broad spectrum of genes that have an impact on atrial development and function.
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Affiliation(s)
- San-pin Wu
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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86
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Ather S, Respress JL, Li N, Wehrens XHT. Alterations in ryanodine receptors and related proteins in heart failure. Biochim Biophys Acta Mol Basis Dis 2013; 1832:2425-31. [PMID: 23770282 DOI: 10.1016/j.bbadis.2013.06.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 04/23/2013] [Accepted: 06/05/2013] [Indexed: 01/07/2023]
Abstract
Sarcoplasmic reticulum (SR) Ca(2+) release plays an essential role in mediating cardiac myocyte contraction. Depolarization of the plasma membrane results in influx of Ca(2+) through l-type Ca(2+) channels (LTCCs) that in turn triggers efflux of Ca(2+) from the SR through ryanodine receptor type-2 channels (RyR2). This process known as Ca(2+)-induced Ca(2+)release (CICR) occurs within the dyadic region, where the adjacent transverse (T)-tubules and SR membranes allow RyR2 clusters to release SR Ca(2+) following Ca(2+) influx through adjacent LTCCs. SR Ca(2+) released during systole binds to troponin-C and initiates actin-myosin cross-bridging, leading to muscle contraction. During diastole, the cytosolic Ca(2+) concentration is restored by the resequestration of Ca(2+) into the SR by SR/ER Ca(2+)-ATPase (SERCA2a) and by the extrusion of Ca(2+) via the Na(+)/Ca(2+)-exchanger (NCX1). This whole process, entitled excitation-contraction (EC) coupling, is highly coordinated and determines the force of contraction, providing a link between the electrical and mechanical activities of cardiac muscle. In response to heart failure (HF), the heart undergoes maladaptive changes that result in depressed intracellular Ca(2+) cycling and decreased SR Ca(2+) concentrations. As a result, the amplitude of CICR is reduced resulting in less force production during EC coupling. In this review, we discuss the specific proteins that alter the regulation of Ca(2+) during HF. In particular, we will focus on defects in RyR2-mediated SR Ca(2+) release. This article is part of a Special Issue entitled: Heart failure pathogenesis and emerging diagnostic and therapeutic interventions.
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Affiliation(s)
- Sameer Ather
- Dept of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Dept of Medicine (Cardiology), Baylor College of Medicine, Houston, TX, USA
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87
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Bombardier E, Smith IC, Gamu D, Fajardo VA, Vigna C, Sayer RA, Gupta SC, Bal NC, Periasamy M, Tupling AR. Sarcolipin trumps β-adrenergic receptor signaling as the favored mechanism for muscle-based diet-induced thermogenesis. FASEB J 2013; 27:3871-8. [PMID: 23752204 DOI: 10.1096/fj.13-230631] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Sarcolipin (SLN) regulates muscle-based nonshivering thermogenesis and is up-regulated with high-fat feeding (HFF). To investigate whether other muscle-based thermogenic systems compensate for a lack of Sln and to firmly establish SLN as a mediator of diet-induced thermogenesis (DIT), we measured muscle and whole-body energy expenditure in chow- and high-fat-fed Sln(-/-) and wild-type (WT) mice. Following HFF, resting muscle metabolic rate (VO2, μl/g/s) was increased similarly in WT (0.28±0.02 vs. 0.31±0.03) and Sln(-/-) (0.23±0.03 vs. 0.35±0.02) mice due to increased sympathetic nervous system activation in Sln(-/-) mice; however, whole-body metabolic rate (VO2, ml/kg/h) was lower in Sln(-/-) compared with WT mice following HFF but only during periods when the mice were active in their cages (WT, 2894±87 vs. Sln(-/-), 2708±61). Treatment with the β-adrenergic receptor (β-AR) antagonist propranolol during HFF completely prevented muscle-based DIT in Sln(-/-) mice; however, it had no effect in WT mice, resulting in greater differences in whole-body metabolic rate and diet-induced weight gain. Our results suggest that β-AR signaling partially compensates for a lack of SLN to activate muscle-based DIT, but SLN is the primary and more effective mediator.
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Affiliation(s)
- Eric Bombardier
- University of Waterloo, Department of Kinesiology, 200 University Ave. W., ON, Canada N2L 3G1
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88
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Schneider JS, Shanmugam M, Gonzalez JP, Lopez H, Gordan R, Fraidenraich D, Babu GJ. Increased sarcolipin expression and decreased sarco(endo)plasmic reticulum Ca2+ uptake in skeletal muscles of mouse models of Duchenne muscular dystrophy. J Muscle Res Cell Motil 2013; 34:349-56. [DOI: 10.1007/s10974-013-9350-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 05/27/2013] [Indexed: 02/02/2023]
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89
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Dibb KM, Clarke JD, Eisner DA, Richards MA, Trafford AW. A functional role for transverse (t-) tubules in the atria. J Mol Cell Cardiol 2013; 58:84-91. [PMID: 23147188 DOI: 10.1016/j.yjmcc.2012.11.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 11/01/2012] [Indexed: 11/17/2022]
Abstract
Mammalian ventricular myocytes are characterised by the presence of an extensive transverse (t-) tubule network which is responsible for the synchronous rise of intracellular Ca(2+) concentration ([Ca(2+)]i) during systole. Disruption to the ventricular t-tubule network occurs in various cardiac pathologies and leads to heterogeneous changes of [Ca(2+)]i which are thought to contribute to the reduced contractility and increased susceptibility to arrhythmias of the diseased ventricle. Here we review evidence that, despite the long-held dogma of atrial cells having no or very few t-tubules, there is indeed an extensive and functionally significant t-tubule network present in atrial myocytes of large mammals including human. Moreover, the atrial t-tubule network is highly plastic in nature and undergoes far more extensive remodelling in heart disease than is the case in the ventricle with profound consequences for the resulting systolic Ca(2+) transient. In addition to considering the functional role of the t-tubule network in the healthy and diseased atria we also provide an overview of recent data concerning the putative factors controlling the formation of t-tubules and conclude by posing some important questions that currently remain to be addressed and whether or not targeting t-tubules offers potential novel therapeutic possibilities for heart disease.
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Affiliation(s)
- Katharine M Dibb
- Institute of Cardiovascular Sciences, Manchester Academic Health Science Centre, 3.08 Core Technology Facility, 46 Grafton Street, Manchester, M13 9PT, UK
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90
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Ablation of sarcolipin decreases the energy requirements for Ca2+ transport by sarco(endo)plasmic reticulum Ca2+-ATPases in resting skeletal muscle. FEBS Lett 2013; 587:1687-92. [PMID: 23628781 DOI: 10.1016/j.febslet.2013.04.019] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/16/2013] [Accepted: 04/16/2013] [Indexed: 11/21/2022]
Abstract
The purpose of this study was to examine the effects of sarcolipin (SLN) on sarco(endo) plasmic reticulum Ca(2+)-ATPase (SERCA pump) energetics in vivo and resting skeletal muscle metabolic rate. Using SLN knockout (Sln(-/-)) mice we show that SLN ablation increases the transport stoichiometry of SERCA pumps (Ca(2+) uptake/Ca(2+)-ATPase activity) and decreases the relative contribution of SERCA pumps to resting oxygen consumption (VO2) in soleus without affecting soleus or whole body VO2. These data suggest that the lower energy requirements for Ca(2+) cycling in resting skeletal muscle of Sln(-/-) mice do not impact significantly either skeletal muscle or whole body metabolic rate.
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91
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Crystal structures of the calcium pump and sarcolipin in the Mg2+-bound E1 state. Nature 2013; 495:260-4. [DOI: 10.1038/nature11899] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 01/11/2013] [Indexed: 11/08/2022]
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92
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Gorski PA, Glaves JP, Vangheluwe P, Young HS. Sarco(endo)plasmic reticulum calcium ATPase (SERCA) inhibition by sarcolipin is encoded in its luminal tail. J Biol Chem 2013; 288:8456-8467. [PMID: 23362265 DOI: 10.1074/jbc.m112.446161] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sarco(endo)plasmic reticulum calcium ATPase (SERCA) is regulated in a tissue-dependent manner via interaction with the short integral membrane proteins phospholamban (PLN) and sarcolipin (SLN). Although defects in SERCA activity are known to cause heart failure, the regulatory mechanisms imposed by PLN and SLN could have clinical implications for both heart and skeletal muscle diseases. PLN and SLN have significant sequence homology in their transmembrane regions, suggesting a similar mode of binding to SERCA. However, unlike PLN, SLN has a conserved C-terminal luminal tail composed of five amino acids ((27)RSYQY), which may contribute to a distinct SERCA regulatory mechanism. We have functionally characterized alanine mutants of the C-terminal tail of SLN using co-reconstituted proteoliposomes of SERCA and SLN. We found that Arg(27) and Tyr(31) are essential for SLN function. We also tested the effect of a truncated variant of SLN (Arg(27)stop) and extended chimeras of PLN with the five luminal residues of SLN added to its C terminus. The Arg(27)stop form of SLN resulted in loss of function, whereas the PLN chimeras resulted in superinhibition with characteristics of both PLN and SLN. Based on our results, we propose that the C-terminal tail of SLN is a distinct, essential domain in the regulation of SERCA and that the functional properties of the SLN tail can be transferred to PLN.
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Affiliation(s)
- Przemek A Gorski
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - John Paul Glaves
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada; National Institute for Nanotechnology, University of Alberta, Edmonton, Alberta T6G 2M9, Canada
| | - Peter Vangheluwe
- Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, B3000 Leuven, Belgium
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada; National Institute for Nanotechnology, University of Alberta, Edmonton, Alberta T6G 2M9, Canada.
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93
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Sahoo SK, Shaikh SA, Sopariwala DH, Bal NC, Periasamy M. Sarcolipin protein interaction with sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA) is distinct from phospholamban protein, and only sarcolipin can promote uncoupling of the SERCA pump. J Biol Chem 2013; 288:6881-9. [PMID: 23341466 DOI: 10.1074/jbc.m112.436915] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Sarco(endo)plasmic reticulum Ca(2+)ATPase (SERCA) pump activity is modulated by phospholamban (PLB) and sarcolipin (SLN) in cardiac and skeletal muscle. Recent data suggest that SLN could play a role in muscle thermogenesis by promoting uncoupling of the SERCA pump (Lee, A.G. (2002) Curr. Opin. Struct. Biol. 12, 547-554 and Bal, N. C., Maurya, S. K., Sopariwala, D. H., Sahoo, S. K., Gupta, S. C., Shaikh, S. A., Pant, M., Rowland, L. A., Bombardier, E., Goonasekera, S. A., Tupling, A. R., Molkentin, J. D., and Periasamy, M. (2012) Nat. Med. 18, 1575-1579), but the mechanistic details are unknown. To better define how binding of SLN to SERCA promotes uncoupling of SERCA, we compared SLN and SERCA1 interaction with that of PLB in detail. The homo-bifunctional cross-linker (1,6-bismaleimidohexane) was employed to detect dynamic protein interaction during the SERCA cycle. Our studies reveal that SLN differs significantly from PLB: 1) SLN primarily affects the Vmax of SERCA-mediated Ca(2+) uptake but not the pump affinity for Ca(2+); 2) SLN can bind to SERCA in the presence of high Ca(2+), but PLB can only interact to the ATP-bound Ca(2+)-free E2 state; and 3) unlike PLB, SLN interacts with SERCA throughout the kinetic cycle and promotes uncoupling of the SERCA pump. Using SERCA transmembrane mutants, we additionally show that PLB and SLN can bind to the same groove but interact with a different set of residues on SERCA. These data collectively suggest that SLN is functionally distinct from PLB; its ability to interact with SERCA in the presence of Ca(2+) causes uncoupling of the SERCA pump and increased heat production.
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Affiliation(s)
- Sanjaya K Sahoo
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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94
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Sarcolipin is a newly identified regulator of muscle-based thermogenesis in mammals. Nat Med 2012; 18:1575-9. [PMID: 22961106 DOI: 10.1038/nm.2897] [Citation(s) in RCA: 399] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 07/09/2012] [Indexed: 11/09/2022]
Abstract
The role of skeletal muscle in nonshivering thermogenesis (NST) is not well understood. Here we show that sarcolipin (Sln), a newly identified regulator of the sarco/endoplasmic reticulum Ca(2+)-ATPase (Serca) pump, is necessary for muscle-based thermogenesis. When challenged to acute cold (4 °C), Sln(-/-) mice were not able to maintain their core body temperature (37 °C) and developed hypothermia. Surgical ablation of brown adipose tissue and functional knockdown of Ucp1 allowed us to highlight the role of muscle in NST. Overexpression of Sln in the Sln-null background fully restored muscle-based thermogenesis, suggesting that Sln is the basis for Serca-mediated heat production. We show that ryanodine receptor 1 (Ryr1)-mediated Ca(2+) leak is an important mechanism for Serca-activated heat generation. Here we present data to suggest that Sln can continue to interact with Serca in the presence of Ca(2+), which can promote uncoupling of the Serca pump and cause futile cycling. We further show that loss of Sln predisposes mice to diet-induced obesity, which suggests that Sln-mediated NST is recruited during metabolic overload. These data collectively suggest that SLN is an important mediator of muscle thermogenesis and whole-body energy metabolism.
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95
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Riley G, Syeda F, Kirchhof P, Fabritz L. An introduction to murine models of atrial fibrillation. Front Physiol 2012; 3:296. [PMID: 22934047 PMCID: PMC3429067 DOI: 10.3389/fphys.2012.00296] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 07/08/2012] [Indexed: 01/28/2023] Open
Abstract
Understanding the mechanism of re-entrant arrhythmias in the past 30 years has allowed the development of almost curative therapies for many rhythm disturbances. The complex, polymorphic arrhythmias of atrial fibrillation (AF) and sudden death are, unfortunately, not yet well understood, and hence still in need of adequate therapy. AF contributes markedly to morbidity and mortality in aging Western populations. In the past decade, many genetically altered murine models have been described and characterized. Here, we review genetically altered murine models of AF; powerful tools that will enable a better understanding of the mechanisms of AF and the assessment of novel therapeutic interventions.
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Affiliation(s)
- Genna Riley
- Centre for Cardiovascular Sciences, School of Clinical and Experimental Medicine, University of Birmingham Birmingham, UK
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96
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Xie LH, Shanmugam M, Park JY, Zhao Z, Wen H, Tian B, Periasamy M, Babu GJ. Ablation of sarcolipin results in atrial remodeling. Am J Physiol Cell Physiol 2012; 302:C1762-71. [PMID: 22496245 DOI: 10.1152/ajpcell.00425.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Sarcolipin (SLN) is a key regulator of sarco(endo)plasmic reticulum (SR) Ca(2+)-ATPase (SERCA), and its expression is altered in diseased atrial myocardium. To determine the precise role of SLN in atrial Ca(2+) homeostasis, we developed a SLN knockout (sln-/-) mouse model and demonstrated that ablation of SLN enhances atrial SERCA pump activity. The present study is designed to determine the long-term effects of enhanced SERCA activity on atrial remodeling in the sln-/- mice. Calcium transient measurements show an increase in atrial SR Ca(2+) load and twitch Ca(2+) transients. Patch-clamping experiments demonstrate activation of the forward mode of sodium/calcium exchanger, increased L-type Ca(2+) channel activity, and prolongation of action potential duration at 90% repolarization in the atrial myocytes of sln-/- mice. Spontaneous Ca(2+) waves, delayed afterdepolarization, and triggered activities are frequent in the atrial myocytes of sln-/- mice. Furthermore, loss of SLN in atria is associated with increased interstitial fibrosis and altered expression of genes encoding collagen and other extracellular matrix proteins. Our results also show that the sln-/- mice are susceptible to atrial arrhythmias upon aging. Together, these findings indicate that ablation of SLN results in increased SERCA activity and SR Ca(2+) load, which, in turn, could cause abnormal intracellular Ca(2+) handling and atrial remodeling.
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Affiliation(s)
- Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, 07103, USA
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97
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Seth M, Li T, Graham V, Burch J, Finch E, Stiber JA, Rosenberg PB. Dynamic regulation of sarcoplasmic reticulum Ca(2+) stores by stromal interaction molecule 1 and sarcolipin during muscle differentiation. Dev Dyn 2012; 241:639-47. [PMID: 22411552 PMCID: PMC3306055 DOI: 10.1002/dvdy.23760] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
During muscle development, the sarco/endoplasmic reticulum (SR/ER) undergoes remodeling to establish a specialized internal Ca(2+) store for muscle contraction. We hypothesized that store operated Ca(2+) entry (SOCE) is required to fill Ca(2+) stores and is, therefore, critical to creating a mature SR/ER. Stromal interaction molecule 1 (STIM1) functions as a sensor of internal Ca(2+) store content and an activator of SOCE channels. Myocytes lacking STIM1 display reduced SR Ca(2+) content and altered expression of key SR proteins. Sarcolipin (SLN), an inhibitor of the SR calcium pump, was markedly increased in the muscle of mutant STIM1 mice. SLN opposes the actions of STIM1 by limiting SOCE, reducing SR Ca(2+) content and delaying muscle differentiation. During mouse muscle development SLN is highly expressed in embryonic muscle, while the expression of STIM1 is up-regulated postnatally. These results suggest that SOCE regulates SR/ER specialization and that SLN and STIM1 act in opposing fashions to govern SOCE during myogenesis.
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Affiliation(s)
- Malini Seth
- Department of Medicine, Duke University, Durham, North Carolina 27710, USA
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98
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Tupling AR, Bombardier E, Gupta SC, Hussain D, Vigna C, Bloemberg D, Quadrilatero J, Trivieri MG, Babu GJ, Backx PH, Periasamy M, MacLennan DH, Gramolini AO. Enhanced Ca2+ transport and muscle relaxation in skeletal muscle from sarcolipin-null mice. Am J Physiol Cell Physiol 2011; 301:C841-9. [PMID: 21697544 DOI: 10.1152/ajpcell.00409.2010] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sarcolipin (SLN) inhibits sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) pumps. To evaluate the physiological significance of SLN in skeletal muscle, we compared muscle contractility and SERCA activity between Sln-null and wild-type mice. SLN protein expression in wild-type mice was abundant in soleus and red gastrocnemius (RG), low in extensor digitorum longus (EDL), and absent from white gastrocnemius (WG). SERCA activity rates were increased in soleus and RG, but not in EDL or WG, from Sln-null muscles, compared with wild type. No differences were seen between wild-type and Sln-null EDL muscles in force-frequency curves or maximum rates of force development (+dF/dt). Maximum relaxation rates (-dF/dt) of EDL were higher in Sln-null than wild type across a range of submaximal stimulation frequencies, but not during a twitch or peak tetanic contraction. For soleus, no differences were seen between wild type and Sln-null in peak tetanic force or +dF/dt; however, force-frequency curves showed that peak force during a twitch and 10-Hz contraction was lower in Sln-null. Changes in the soleus force-frequency curve corresponded with faster rates of force relaxation at nearly all stimulation frequencies in Sln-null compared with wild type. Repeated tetanic stimulation of soleus caused increased (-dF/dt) in wild type, but not in Sln-null. No compensatory responses were detected in analysis of other Ca(2+) regulatory proteins using Western blotting and immunohistochemistry or myosin heavy chain expression using immunofluorescence. These results show that 1) SLN regulates Ca(2+)-ATPase activity thereby regulating contractile kinetics in at least some skeletal muscles, 2) the functional significance of SLN is graded to the endogenous SLN expression level, and 3) SLN inhibitory effects on SERCA function are relieved in response to repeated contractions thus enhancing relaxation rates.
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99
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Decreased sarcolipin protein expression and enhanced sarco(endo)plasmic reticulum Ca2+ uptake in human atrial fibrillation. Biochem Biophys Res Commun 2011; 410:97-101. [PMID: 21640081 DOI: 10.1016/j.bbrc.2011.05.113] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 05/19/2011] [Indexed: 11/24/2022]
Abstract
Sarcolipin (SLN), a key regulator of cardiac sarco(endo)plasmic reticulum (SR) Ca(2+) ATPase, is predominantly expressed in atria and mediates β-adrenergic responses. Studies have shown that SLN mRNA expression is decreased in human chronic atrial fibrillation (AF) and in aortic banded mouse atria; however, SLN protein expression in human atrial pathology and its role in atrial SR Ca(2+) uptake are not yet elucidated. In the present study, we determined the expression of major SR Ca(2+) handling proteins in atria of human AF patients and in human and in a mouse model of heart failure (HF). We found that the expression of SR Ca(2+) uptake and Ca(2+) release channel proteins are significantly decreased in atria but not in the ventricles of pressure-overload induced HF in mice. In human AF and HF, the expression of SLN protein was significantly decreased; whereas the expressions of other major SR Ca(2+) handling proteins were not altered. Further, we found that the SR Ca(2+) uptake was significantly increased in human AF. The selective downregulation of SLN and enhanced SR Ca(2+) uptake in human AF suggest that SLN downregulation could play an important role in abnormal intracellular Ca(2+) cycling in atrial pathology.
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100
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Vandecaetsbeek I, Vangheluwe P, Raeymaekers L, Wuytack F, Vanoevelen J. The Ca2+ pumps of the endoplasmic reticulum and Golgi apparatus. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a004184. [PMID: 21441596 DOI: 10.1101/cshperspect.a004184] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The various splice variants of the three SERCA- and the two SPCA-pump genes in higher vertebrates encode P-type ATPases of the P(2A) group found respectively in the membranes of the endoplasmic reticulum and the secretory pathway. Of these, SERCA2b and SPCA1a represent the housekeeping isoforms. The SERCA2b form is characterized by a luminal carboxy terminus imposing a higher affinity for cytosolic Ca(2+) compared to the other SERCAs. This is mediated by intramembrane and luminal interactions of this extension with the pump. Other known affinity modulators like phospholamban and sarcolipin decrease the affinity for Ca(2+). The number of proteins reported to interact with SERCA is rapidly growing. Here, we limit the discussion to those for which the interaction site with the ATPase is specified: HAX-1, calumenin, histidine-rich Ca(2+)-binding protein, and indirectly calreticulin, calnexin, and ERp57. The role of the phylogenetically older and structurally simpler SPCAs as transporters of Ca(2+), but also of Mn(2+), is also addressed.
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Affiliation(s)
- Ilse Vandecaetsbeek
- Laboratory of Ca-transport ATPases, Department of Molecular Cell Biology, K.U. Leuven, Leuven, Belgium
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