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Hord JM, Anderson ME, Prouty SJ, Melton S, Gastel Z, Zimmerman K, Weiss RM, Campbell KP. Matriglycan maintains t-tubule structural integrity in cardiac muscle. Proc Natl Acad Sci U S A 2024; 121:e2402890121. [PMID: 38771868 PMCID: PMC11145246 DOI: 10.1073/pnas.2402890121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 04/08/2024] [Indexed: 05/23/2024] Open
Abstract
Maintaining the structure of cardiac membranes and membrane organelles is essential for heart function. A critical cardiac membrane organelle is the transverse tubule system (called the t-tubule system) which is an invagination of the surface membrane. A unique structural characteristic of the cardiac muscle t-tubule system is the extension of the extracellular matrix (ECM) from the surface membrane into the t-tubule lumen. However, the importance of the ECM extending into the cardiac t-tubule lumen is not well understood. Dystroglycan (DG) is an ECM receptor in the surface membrane of many cells, and it is also expressed in t-tubules in cardiac muscle. Extensive posttranslational processing and O-glycosylation are required for DG to bind ECM proteins and the binding is mediated by a glycan structure known as matriglycan. Genetic disruption resulting in defective O-glycosylation of DG results in muscular dystrophy with cardiorespiratory pathophysiology. Here, we show that DG is essential for maintaining cardiac t-tubule structural integrity. Mice with defects in O-glycosylation of DG developed normal t-tubules but were susceptible to stress-induced t-tubule loss or severing that contributed to cardiac dysfunction and disease progression. Finally, we observed similar stress-induced cardiac t-tubule disruption in a cohort of mice that solely lacked matriglycan. Collectively, our data indicate that DG in t-tubules anchors the luminal ECM to the t-tubule membrane via the polysaccharide matriglycan, which is critical to transmitting structural strength of the ECM to the t-tubules and provides resistance to mechanical stress, ultimately preventing disruptions in cardiac t-tubule integrity.
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Affiliation(s)
- Jeffrey M. Hord
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Mary E. Anderson
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Sally J. Prouty
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Shelly Melton
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Zeita Gastel
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Kathy Zimmerman
- Division of Cardiology, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Robert M. Weiss
- Division of Cardiology, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Abboud Cardiovascular Research Center, Carver College of Medicine, Department of Internal Medicine-Cardiovascular Medicine, University of Iowa, Iowa City, IA52242
- Iowa City Veterans Affairs Health Care System, University of Iowa, Iowa City, IA52242
| | - Kevin P. Campbell
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
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Scardigli M, Pásek M, Santini L, Palandri C, Conti E, Crocini C, Campione M, Loew LM, de Vries AAF, Pijnappels DA, Pavone FS, Poggesi C, Cerbai E, Coppini R, Kohl P, Ferrantini C, Sacconi L. Optogenetic confirmation of transverse-tubular membrane excitability in intact cardiac myocytes. J Physiol 2024; 602:791-808. [PMID: 38348881 DOI: 10.1113/jp285202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 01/17/2024] [Indexed: 03/09/2024] Open
Abstract
T-tubules (TT) form a complex network of sarcolemmal membrane invaginations, essential for well-co-ordinated excitation-contraction coupling (ECC) and thus homogeneous mechanical activation of cardiomyocytes. ECC is initiated by rapid depolarization of the sarcolemmal membrane. Whether TT membrane depolarization is active (local generation of action potentials; AP) or passive (following depolarization of the outer cell surface sarcolemma; SS) has not been experimentally validated in cardiomyocytes. Based on the assessment of ion flux pathways needed for AP generation, we hypothesize that TT are excitable. We therefore explored TT excitability experimentally, using an all-optical approach to stimulate and record trans-membrane potential changes in TT that were structurally disconnected, and hence electrically insulated, from the SS membrane by transient osmotic shock. Our results establish that cardiomyocyte TT can generate AP. These AP show electrical features that differ substantially from those observed in SS, consistent with differences in the density of ion channels and transporters in the two different membrane domains. We propose that TT-generated AP represent a safety mechanism for TT AP propagation and ECC, which may be particularly relevant in pathophysiological settings where morpho-functional changes reduce the electrical connectivity between SS and TT membranes. KEY POINTS: Cardiomyocytes are characterized by a complex network of membrane invaginations (the T-tubular system) that propagate action potentials to the core of the cell, causing uniform excitation-contraction coupling across the cell. In the present study, we investigated whether the T-tubular system is able to generate action potentials autonomously, rather than following depolarization of the outer cell surface sarcolemma. For this purpose, we developed a fully optical platform to probe and manipulate the electrical dynamics of subcellular membrane domains. Our findings demonstrate that T-tubules are intrinsically excitable, revealing distinct characteristics of self-generated T-tubular action potentials. This active electrical capability would protect cells from voltage drops potentially occurring within the T-tubular network.
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Affiliation(s)
- Marina Scardigli
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Michal Pásek
- Institute of Thermomechanics, Czech Academy of Science, Prague, Czech Republic
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Lorenzo Santini
- Department of Neurology, Psychology, Drug Sciences and Child Health, University of Florence, Florence, Italy
| | - Chiara Palandri
- Department of Neurology, Psychology, Drug Sciences and Child Health, University of Florence, Florence, Italy
| | - Emilia Conti
- European Laboratory for Non-Linear Spectroscopy - LENS, Sesto Fiorentino, Italy
- Neuroscience Institute, National Research Council, Pisa, Italy
| | - Claudia Crocini
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Berlin, Germany
- Max Rubner Center for Cardiovascular Metabolic Renal Research (MRC), Deutsches Herzzentrum der Charité (DHZC), Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Marina Campione
- Institute of Neuroscience (IN-CNR) and Department of Biomedical Science, University of Padua, Padua, Italy
| | - Leslie M Loew
- Center for Cell Analysis and Modeling, University of Connecticut, Farmington, CT, USA
| | - Antoine A F de Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Daniël A Pijnappels
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Francesco S Pavone
- European Laboratory for Non-Linear Spectroscopy - LENS, Sesto Fiorentino, Italy
| | - Corrado Poggesi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Elisabetta Cerbai
- Department of Neurology, Psychology, Drug Sciences and Child Health, University of Florence, Florence, Italy
- European Laboratory for Non-Linear Spectroscopy - LENS, Sesto Fiorentino, Italy
| | - Raffaele Coppini
- Department of Neurology, Psychology, Drug Sciences and Child Health, University of Florence, Florence, Italy
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Cecilia Ferrantini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Leonardo Sacconi
- European Laboratory for Non-Linear Spectroscopy - LENS, Sesto Fiorentino, Italy
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Medical Faculty, University of Freiburg, Freiburg, Germany
- Institute of Clinical Physiology, National Research Council (IFC-CNR), Florence, Italy
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3
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Zhang X, Ni H, Morotti S, Smith C, Sato D, Louch W, Edwards A, Grandi E. Mechanisms of spontaneous Ca 2+ release-mediated arrhythmia in a novel 3D human atrial myocyte model: I. Transverse-axial tubule variation. J Physiol 2023; 601:2655-2683. [PMID: 36094888 PMCID: PMC10008525 DOI: 10.1113/jp283363] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/02/2022] [Indexed: 11/08/2022] Open
Abstract
Intracellular calcium (Ca2+ ) cycling is tightly regulated in the healthy heart ensuring effective contraction. This is achieved by transverse (t)-tubule membrane invaginations that facilitate close coupling of key Ca2+ -handling proteins such as the L-type Ca2+ channel and Na+ -Ca2+ exchanger (NCX) on the cell surface with ryanodine receptors (RyRs) on the intracellular Ca2+ store. Although less abundant and regular than in the ventricle, t-tubules also exist in atrial myocytes as a network of transverse invaginations with axial extensions known as the transverse-axial tubule system (TATS). In heart failure and atrial fibrillation, there is TATS remodelling that is associated with aberrant Ca2+ -handling and Ca2+ -induced arrhythmic activity; however, the mechanism underlying this is not fully understood. To address this, we developed a novel 3D human atrial myocyte model that couples electrophysiology and Ca2+ -handling with variable TATS organization and density. We extensively parameterized and validated our model against experimental data to build a robust tool examining TATS regulation of subcellular Ca2+ release. We found that varying TATS density and thus the localization of key Ca2+ -handling proteins has profound effects on Ca2+ handling. Following TATS loss, there is reduced NCX that results in increased cleft Ca2+ concentration through decreased Ca2+ extrusion. This elevated Ca2+ increases RyR open probability causing spontaneous Ca2+ releases and the promotion of arrhythmogenic waves (especially in the cell interior) leading to voltage instabilities through delayed afterdepolarizations. In summary, the present study demonstrates a mechanistic link between TATS remodelling and Ca2+ -driven proarrhythmic behaviour that probably reflects the arrhythmogenic state observed in disease. KEY POINTS: Transverse-axial tubule systems (TATS) modulate Ca2+ handling and excitation-contraction coupling in atrial myocytes, with TATS remodelling in heart failure and atrial fibrillation being associated with altered Ca2+ cycling and subsequent arrhythmogenesis. To investigate the poorly understood mechanisms linking TATS variation and spontaneous Ca2+ release, we built, parameterized and validated a 3D human atrial myocyte model coupling electrophysiology and spatially-detailed subcellular Ca2+ handling governed by the TATS. Simulated TATS loss causes diastolic Ca2+ and voltage instabilities through reduced Na+ -Ca2+ exchanger-mediated Ca2+ removal, cleft Ca2+ accumulation and increased ryanodine receptor open probability, resulting in spontaneous Ca2+ release and promotion of arrhythmogenic waves and delayed afterdepolarizations. At fast electrical rates typical of atrial tachycardia/fibrillation, spontaneous Ca2+ releases are larger and more frequent in the cell interior than at the periphery. Our work provides mechanistic insight into how atrial TATS remodelling can lead to Ca2+ -driven instabilities that may ultimately contribute to the arrhythmogenic state in disease.
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Affiliation(s)
- X. Zhang
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - H. Ni
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - S. Morotti
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - C.E.R. Smith
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - D. Sato
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - W.E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
| | - A.G. Edwards
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- Simula Research Laboratory, Lysaker, Norway
| | - E. Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
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4
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Szentesi P, Dienes B, Kutchukian C, Czirjak T, Buj-Bello A, Jacquemond V, Csernoch L. Disrupted T-tubular network accounts for asynchronous calcium release in MTM1-deficient skeletal muscle. J Physiol 2023; 601:99-121. [PMID: 36408764 PMCID: PMC10107287 DOI: 10.1113/jp283650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/14/2022] [Indexed: 11/22/2022] Open
Abstract
In mammalian skeletal muscle, the propagation of surface membrane depolarization into the interior of the muscle fibre along the transverse (T) tubular network is essential for the synchronized release of calcium from the sarcoplasmic reticulum (SR) via ryanodine receptors (RyRs) in response to the conformational change in the voltage-sensor dihydropyridine receptors. Deficiency in 3-phosphoinositide phosphatase myotubularin (MTM1) has been reported to disrupt T-tubules, resulting in impaired SR calcium release. Here confocal calcium transients recorded in muscle fibres of MTM1-deficient mice were compared with the results from a model where propagation of the depolarization along the T-tubules was modelled mathematically with disruptions in the network assumed to modify the access and transmembrane resistance as well as the capacitance. If, in simulations, T-tubules were assumed to be partially or completely inaccessible to the depolarization and RyRs at these points to be prime for calcium-induced calcium release, all the features of measured SR calcium release could be reproduced. We conclude that the inappropriate propagation of the depolarization into the fibre interior is the initial critical cause of severely impaired SR calcium release in MTM1 deficiency, while the Ca2+ -triggered opening of RyRs provides an alleviating support to the diseased process. KEY POINTS: Myotubular myopathy is a fatal disease due to genetic deficiency in the phosphoinositide phosphatase MTM1. Although the causes are known and corresponding gene therapy strategies are being developed, there is no mechanistic understanding of the disease-associated muscle function failure. Resolving this issue is of primary interest not only for a fundamental understanding of how MTM1 is critical for healthy muscle function, but also for establishing the related cellular mechanisms most primarily or stringently affected by the disease, which are thus of potential interest as therapy targets. The mathematical modelling approach used in the present work proves that the disease-associated alteration of the plasma membrane invagination network is sufficient to explain the dysfunctions of excitation-contraction coupling, providing the first integrated quantitative framework that explains the associated contraction failure.
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Affiliation(s)
- Peter Szentesi
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Candice Kutchukian
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5261, INSERM U-1315, Institut NeuroMyoGène, Lyon, France
| | - Tamas Czirjak
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Ana Buj-Bello
- Genethon, Evry, France.,Université Paris-Saclay, Evry, France
| | - Vincent Jacquemond
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5261, INSERM U-1315, Institut NeuroMyoGène, Lyon, France
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,ELRN-UD Cell Physiology Research Group, Debrecen, Hungary
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Fowler ED, Wang N, Hezzell MJ, Chanoit G, Hancox JC, Cannell MB. Improved Ca 2+ release synchrony following selective modification of I tof and phase 1 repolarization in normal and failing ventricular myocytes. J Mol Cell Cardiol 2022; 172:52-62. [PMID: 35908686 DOI: 10.1016/j.yjmcc.2022.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 12/14/2022]
Abstract
Loss of ventricular action potential (AP) early phase 1 repolarization may contribute to the impaired Ca2+ release and increased risk of sudden cardiac death in heart failure. Therefore, restoring AP phase 1 by augmenting the fast transient outward K+ current (Itof) might be beneficial, but direct experimental evidence to support this proposition in failing cardiomyocytes is limited. Dynamic clamp was used to selectively modulate the contribution of Itof to the AP and Ca2+ transient in both normal (guinea pig and rabbit) and in failing rabbit cardiac myocytes. Opposing native Itof in non-failing rabbit myocytes increased Ca2+ release heterogeneity, late Ca2+ sparks (LCS) frequency and AP duration. (APD). In contrast, increasing Itof in failing myocytes and guinea pig myocytes (the latter normally lacking Itof) increased Ca2+ transient amplitude, Ca2+ release synchrony, and shortened APD. Computer simulations also showed faster Ca2+ transient decay (mainly due to fewer LCS), decreased inward Na+/Ca2+ exchange current and APD. When the Itof conductance was increased to ~0.2 nS/pF in failing cells (a value slightly greater than seen in typical human epicardial myocytes), Ca2+ release synchrony improved and AP duration decreased slightly. Further increases in Itof can cause Ca2+ release to decrease as the peak of the bell-shaped ICa-voltage relationship is passed and premature AP repolarization develops. These results suggest that there is an optimal range for Itof enhancement that may support Ca2+ release synchrony and improve electrical stability in heart failure with the caveat that uncontrolled Itof enhancement should be avoided.
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Affiliation(s)
- Ewan D Fowler
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Nan Wang
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Melanie J Hezzell
- University of Bristol Veterinary School, Langford, Bristol BS40 5DU, UK
| | - Guillaume Chanoit
- University of Bristol Veterinary School, Langford, Bristol BS40 5DU, UK
| | - Jules C Hancox
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Mark B Cannell
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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6
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Müllenbroich MC, Kelly A, Acker C, Bub G, Bruegmann T, Di Bona A, Entcheva E, Ferrantini C, Kohl P, Lehnart SE, Mongillo M, Parmeggiani C, Richter C, Sasse P, Zaglia T, Sacconi L, Smith GL. Novel Optics-Based Approaches for Cardiac Electrophysiology: A Review. Front Physiol 2021; 12:769586. [PMID: 34867476 PMCID: PMC8637189 DOI: 10.3389/fphys.2021.769586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 10/18/2021] [Indexed: 12/31/2022] Open
Abstract
Optical techniques for recording and manipulating cellular electrophysiology have advanced rapidly in just a few decades. These developments allow for the analysis of cardiac cellular dynamics at multiple scales while largely overcoming the drawbacks associated with the use of electrodes. The recent advent of optogenetics opens up new possibilities for regional and tissue-level electrophysiological control and hold promise for future novel clinical applications. This article, which emerged from the international NOTICE workshop in 2018, reviews the state-of-the-art optical techniques used for cardiac electrophysiological research and the underlying biophysics. The design and performance of optical reporters and optogenetic actuators are reviewed along with limitations of current probes. The physics of light interaction with cardiac tissue is detailed and associated challenges with the use of optical sensors and actuators are presented. Case studies include the use of fluorescence recovery after photobleaching and super-resolution microscopy to explore the micro-structure of cardiac cells and a review of two photon and light sheet technologies applied to cardiac tissue. The emergence of cardiac optogenetics is reviewed and the current work exploring the potential clinical use of optogenetics is also described. Approaches which combine optogenetic manipulation and optical voltage measurement are discussed, in terms of platforms that allow real-time manipulation of whole heart electrophysiology in open and closed-loop systems to study optimal ways to terminate spiral arrhythmias. The design and operation of optics-based approaches that allow high-throughput cardiac electrophysiological assays is presented. Finally, emerging techniques of photo-acoustic imaging and stress sensors are described along with strategies for future development and establishment of these techniques in mainstream electrophysiological research.
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Affiliation(s)
| | - Allen Kelly
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Corey Acker
- Center for Cell Analysis and Modeling, UConn Health, Farmington, CT, United States
| | - Gil Bub
- Department of Physiology, McGill University, Montréal, QC, Canada
| | - Tobias Bruegmann
- Institute for Cardiovascular Physiology, University Medical Center Goettingen, Goettingen, Germany
| | - Anna Di Bona
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padova, Padova, Italy
| | - Emilia Entcheva
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States
| | | | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Stephan E. Lehnart
- Heart Research Center Göttingen, University Medical Center Göttingen, Göttingen, Germany
- Department of Cardiology and Pneumology, Georg-August University Göttingen, Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
| | - Marco Mongillo
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
| | | | - Claudia Richter
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Tania Zaglia
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
| | - Leonardo Sacconi
- European Laboratory for Nonlinear Spectroscopy, Sesto Fiorentino, Italy
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Medical Faculty, University of Freiburg, Freiburg, Germany
- National Institute of Optics, National Research Council, Florence, Italy
| | - Godfrey L. Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
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7
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Wright PT, Gorelik J, Harding SE. Electrophysiological Remodeling: Cardiac T-Tubules and ß-Adrenoceptors. Cells 2021; 10:cells10092456. [PMID: 34572106 PMCID: PMC8468945 DOI: 10.3390/cells10092456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 01/09/2023] Open
Abstract
Beta-adrenoceptors (βAR) are often viewed as archetypal G-protein coupled receptors. Over the past fifteen years, investigations in cardiovascular biology have provided remarkable insights into this receptor family. These studies have shifted pharmacological dogma, from one which centralized the receptor to a new focus on structural micro-domains such as caveolae and t-tubules. Important studies have examined, separately, the structural compartmentation of ion channels and βAR. Despite links being assumed, relatively few studies have specifically examined the direct link between structural remodeling and electrical remodeling with a focus on βAR. In this review, we will examine the nature of receptor and ion channel dysfunction on a substrate of cardiomyocyte microdomain remodeling, as well as the likely ramifications for cardiac electrophysiology. We will then discuss the advances in methodologies in this area with a specific focus on super-resolution microscopy, fluorescent imaging, and new approaches involving microdomain specific, polymer-based agonists. The advent of powerful computational modelling approaches has allowed the science to shift from purely empirical work, and may allow future investigations based on prediction. Issues such as the cross-reactivity of receptors and cellular heterogeneity will also be discussed. Finally, we will speculate as to the potential developments within this field over the next ten years.
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Affiliation(s)
- Peter T. Wright
- School of Life & Health Sciences, University of Roehampton, Holybourne Avenue, London SW15 4JD, UK;
- Cardiac Section, National Heart and Lung Institute (NHLI), Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK;
| | - Julia Gorelik
- Cardiac Section, National Heart and Lung Institute (NHLI), Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK;
| | - Sian E. Harding
- Cardiac Section, National Heart and Lung Institute (NHLI), Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK;
- Correspondence:
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8
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Altomare C, Lodrini AM, Milano G, Biemmi V, Lazzarini E, Bolis S, Pernigoni N, Torre E, Arici M, Ferrandi M, Barile L, Rocchetti M, Vassalli G. Structural and Electrophysiological Changes in a Model of Cardiotoxicity Induced by Anthracycline Combined With Trastuzumab. Front Physiol 2021; 12:658790. [PMID: 33897465 PMCID: PMC8058443 DOI: 10.3389/fphys.2021.658790] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/16/2021] [Indexed: 11/29/2022] Open
Abstract
Background Combined treatment with anthracyclines (e.g., doxorubicin; Dox) and trastuzumab (Trz), a humanized anti-human epidermal growth factor receptor 2 (HER2; ErbB2) antibody, in patients with HER2-positive cancer is limited by cardiotoxicity, as manifested by contractile dysfunction and arrhythmia. The respective roles of the two agents in the cardiotoxicity of the combined therapy are incompletely understood. Objective To assess cardiac performance, T-tubule organization, electrophysiological changes and intracellular Ca2+ handling in cardiac myocytes (CMs) using an in vivo rat model of Dox/Trz-related cardiotoxicity. Methods and Results Adult rats received 6 doses of either Dox or Trz, or the two agents sequentially. Dox-mediated left ventricular (LV) dysfunction was aggravated by Trz administration. Dox treatment, but not Trz, induced T-tubule disarray. Moreover, Dox, but not Trz monotherapy, induced prolonged action potential duration (APD), increased incidence of delayed afterdepolarizations (DADs) and beat-to-beat variability of repolarization (BVR), and slower Ca2+ transient decay. Although APD, DADs, BVR and Ca2+ transient decay recovered over time after the cessation of Dox treatment, subsequent Trz administration exacerbated these abnormalities. Trz, but not Dox, reduced Ca2+ transient amplitude and SR Ca2+ content, although only Dox treatment was associated with SERCA downregulation. Finally, Dox treatment increased Ca2+ spark frequency, resting Ca2+ waves, sarcoplasmic reticulum (SR) Ca2+ leak, and long-lasting Ca2+ release events (so-called Ca2+ “embers”), partially reproduced by Trz treatment. Conclusion These results suggest that in vivo Dox but not Trz administration causes T-tubule disarray and pronounced changes in electrical activity of CMs. While adaptive changes may account for normal AP shape and reduced DADs late after Dox administration, subsequent Trz administration interferes with such adaptive changes. Intracellular Ca2+ handling was differently affected by Dox and Trz treatment, leading to SR instability in both cases. These findings illustrate the specific roles of Dox and Trz, and their interactions in cardiotoxicity and arrhythmogenicity.
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Affiliation(s)
- Claudia Altomare
- Laboratory of Cellular and Molecular Cardiology, Cardiocentro Ticino Foundation, Lugano, Switzerland
| | - Alessandra Maria Lodrini
- Department of Biotechnology and Biosciences, Università degli Studi di Milano - Bicocca, Milan, Italy.,Laboratory for Cardiovascular Theranostics, Cardiocentro Ticino Foundation, Lugano, Switzerland
| | - Giuseppina Milano
- Laboratory of Cellular and Molecular Cardiology, Cardiocentro Ticino Foundation, Lugano, Switzerland.,Laboratory of Cardiovascular Research, Lausanne University Hospital, Lausanne, Switzerland
| | - Vanessa Biemmi
- Laboratory for Cardiovascular Theranostics, Cardiocentro Ticino Foundation, Lugano, Switzerland
| | - Edoardo Lazzarini
- Laboratory for Cardiovascular Theranostics, Cardiocentro Ticino Foundation, Lugano, Switzerland
| | - Sara Bolis
- Laboratory of Cellular and Molecular Cardiology, Cardiocentro Ticino Foundation, Lugano, Switzerland.,Laboratory for Cardiovascular Theranostics, Cardiocentro Ticino Foundation, Lugano, Switzerland
| | - Nicolò Pernigoni
- Laboratory of Cellular and Molecular Cardiology, Cardiocentro Ticino Foundation, Lugano, Switzerland
| | - Eleonora Torre
- Department of Biotechnology and Biosciences, Università degli Studi di Milano - Bicocca, Milan, Italy
| | - Martina Arici
- Department of Biotechnology and Biosciences, Università degli Studi di Milano - Bicocca, Milan, Italy
| | - Mara Ferrandi
- Windtree Therapeutics Inc., Warrington, PA, United States
| | - Lucio Barile
- Laboratory for Cardiovascular Theranostics, Cardiocentro Ticino Foundation, Lugano, Switzerland.,Faculty of Biomedical Sciences, Università della Svizzera italiana, Lugano, Switzerland.,Institute of Life Science, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Marcella Rocchetti
- Department of Biotechnology and Biosciences, Università degli Studi di Milano - Bicocca, Milan, Italy
| | - Giuseppe Vassalli
- Laboratory of Cellular and Molecular Cardiology, Cardiocentro Ticino Foundation, Lugano, Switzerland.,Faculty of Biomedical Sciences, Università della Svizzera italiana, Lugano, Switzerland.,Center for Molecular Cardiology, University of Zurich, Zurich, Switzerland
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9
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Fiegle DJ, Schöber M, Dittrich S, Cesnjevar R, Klingel K, Volk T, Alkassar M, Seidel T. Severe T-System Remodeling in Pediatric Viral Myocarditis. Front Cardiovasc Med 2021; 7:624776. [PMID: 33537349 PMCID: PMC7848076 DOI: 10.3389/fcvm.2020.624776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 12/22/2020] [Indexed: 12/26/2022] Open
Abstract
Chronic heart failure (HF) in adults causes remodeling of the cardiomyocyte transverse tubular system (t-system), which contributes to disease progression by impairing excitation-contraction (EC) coupling. However, it is unknown if t-system remodeling occurs in pediatric heart failure. This study investigated the t-system in pediatric viral myocarditis. The t-system and integrity of EC coupling junctions (co-localization of L-type Ca2+ channels with ryanodine receptors and junctophilin-2) were analyzed by 3D confocal microscopy in left-ventricular (LV) samples from 5 children with myocarditis (age 14 ± 3 months), undergoing ventricular assist device (VAD) implantation, and 5 children with atrioventricular septum defect (AVSD, age 17 ± 3 months), undergoing corrective surgery. LV ejection fraction (EF) was 58.4 ± 2.3% in AVSD and 12.2 ± 2.4% in acute myocarditis. Cardiomyocytes from myocarditis samples showed increased t-tubule distance (1.27 ± 0.05 μm, n = 34 cells) and dilation of t-tubules (volume-length ratio: 0.64 ± 0.02 μm2) when compared with AVSD (0.90 ± 0.02 μm, p < 0.001; 0.52 ± 0.02 μm2, n = 61, p < 0.01). Intriguingly, 4 out of 5 myocarditis samples exhibited sheet-like t-tubules (t-sheets), a characteristic feature of adult chronic heart failure. The fraction of extracellular matrix was slightly higher in myocarditis (26.6 ± 1.4%) than in AVSD samples (24.4 ± 0.8%, p < 0.05). In one case of myocarditis, a second biopsy was taken and analyzed at VAD explantation after extensive cardiac recovery (EF from 7 to 56%) and clinical remission. When compared with pre-VAD, t-tubule distance and density were unchanged, as well as volume-length ratio (0.67 ± 0.04 μm2 vs. 0.72 ± 0.05 μm2, p = 0.5), reflecting extant t-sheets. However, junctophilin-2 cluster density was considerably higher (0.12 ± 0.02 μm−3 vs. 0.05 ± 0.01 μm−3, n = 9/10, p < 0.001), approaching values of AVSD (0.13 ± 0.05 μm−3, n = 56), and the measure of intact EC coupling junctions showed a distinct increase (20.2 ± 5.0% vs. 6.8 ± 2.2%, p < 0.001). Severe t-system loss and remodeling to t-sheets can occur in acute HF in young children, resembling the structural changes of chronically failing adult hearts. T-system remodeling might contribute to cardiac dysfunction in viral myocarditis. Although t-system recovery remains elusive, recovery of EC coupling junctions may be possible and deserves further investigation.
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Affiliation(s)
- Dominik J Fiegle
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Martin Schöber
- Department of Pediatric Cardiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sven Dittrich
- Department of Pediatric Cardiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Robert Cesnjevar
- Department of Pediatric Cardiac Surgery, University Hospital Erlangen, Erlangen, Germany
| | - Karin Klingel
- Cardiopathology, University Hospital Tuebingen, Tübingen, Germany
| | - Tilmann Volk
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Muhannad Alkassar
- Department of Pediatric Cardiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Thomas Seidel
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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10
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Rog-Zielinska EA, Scardigli M, Peyronnet R, Zgierski-Johnston CM, Greiner J, Madl J, O'Toole ET, Morphew M, Hoenger A, Sacconi L, Kohl P. Beat-by-Beat Cardiomyocyte T-Tubule Deformation Drives Tubular Content Exchange. Circ Res 2020; 128:203-215. [PMID: 33228470 PMCID: PMC7834912 DOI: 10.1161/circresaha.120.317266] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Supplemental Digital Content is available in the text. The sarcolemma of cardiomyocytes contains many proteins that are essential for electromechanical function in general, and excitation-contraction coupling in particular. The distribution of these proteins is nonuniform between the bulk sarcolemmal surface and membrane invaginations known as transverse tubules (TT). TT form an intricate network of fluid-filled conduits that support electromechanical synchronicity within cardiomyocytes. Although continuous with the extracellular space, the narrow lumen and the tortuous structure of TT can form domains of restricted diffusion. As a result of unequal ion fluxes across cell surface and TT membranes, limited diffusion may generate ion gradients within TT, especially deep within the TT network and at high pacing rates.
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Affiliation(s)
- Eva A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, and Faculty of Medicine, University of Freiburg, Germany (E.A.R.-Z., R.P., C.M.Z.-J., J.G., J.M., L.S., P.K.)
| | - Marina Scardigli
- European Laboratory for Non-Linear Spectroscopy, National Institute of Optics, National Research Council, Sesto Fiorentino (Florence), Italy (M.S., L.S.)
| | - Remi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, and Faculty of Medicine, University of Freiburg, Germany (E.A.R.-Z., R.P., C.M.Z.-J., J.G., J.M., L.S., P.K.)
| | - Callum M Zgierski-Johnston
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, and Faculty of Medicine, University of Freiburg, Germany (E.A.R.-Z., R.P., C.M.Z.-J., J.G., J.M., L.S., P.K.)
| | - Joachim Greiner
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, and Faculty of Medicine, University of Freiburg, Germany (E.A.R.-Z., R.P., C.M.Z.-J., J.G., J.M., L.S., P.K.)
| | - Josef Madl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, and Faculty of Medicine, University of Freiburg, Germany (E.A.R.-Z., R.P., C.M.Z.-J., J.G., J.M., L.S., P.K.)
| | - Eileen T O'Toole
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder (E.T.O., M.M., A.H.)
| | - Mary Morphew
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder (E.T.O., M.M., A.H.)
| | - Andreas Hoenger
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder (E.T.O., M.M., A.H.)
| | - Leonardo Sacconi
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, and Faculty of Medicine, University of Freiburg, Germany (E.A.R.-Z., R.P., C.M.Z.-J., J.G., J.M., L.S., P.K.).,European Laboratory for Non-Linear Spectroscopy, National Institute of Optics, National Research Council, Sesto Fiorentino (Florence), Italy (M.S., L.S.)
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, and Faculty of Medicine, University of Freiburg, Germany (E.A.R.-Z., R.P., C.M.Z.-J., J.G., J.M., L.S., P.K.).,CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Germany (P.K.)
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11
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T-tubule remodeling in human hypertrophic cardiomyopathy. J Muscle Res Cell Motil 2020; 42:305-322. [PMID: 33222034 PMCID: PMC8332592 DOI: 10.1007/s10974-020-09591-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 10/22/2020] [Indexed: 11/17/2022]
Abstract
The highly organized transverse T-tubule membrane system represents the ultrastructural substrate for excitation–contraction coupling in ventricular myocytes. While the architecture and function of T-tubules have been well described in animal models, there is limited morpho-functional data on T-tubules in human myocardium. Hypertrophic cardiomyopathy (HCM) is a primary disease of the heart muscle, characterized by different clinical presentations at the various stages of its progression. Most HCM patients, indeed, show a compensated hypertrophic disease (“non-failing hypertrophic phase”), with preserved left ventricular function, and only a small subset of individuals evolves into heart failure (“end stage HCM”). In terms of T-tubule remodeling, the “end-stage” disease does not differ from other forms of heart failure. In this review we aim to recapitulate the main structural features of T-tubules during the “non-failing hypertrophic stage” of human HCM by revisiting data obtained from human myectomy samples. Moreover, by comparing pathological changes observed in myectomy samples with those introduced by acute (experimentally induced) detubulation, we discuss the role of T-tubular disruption as a part of the complex excitation–contraction coupling remodeling process that occurs during disease progression. Lastly, we highlight how T-tubule morpho-functional changes may be related to patient genotype and we discuss the possibility of a primitive remodeling of the T-tubule system in rare HCM forms associated with genes coding for proteins implicated in T-tubule structural integrity, formation and maintenance.
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12
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Christé G, Bonvallet R, Chouabe C. Accounting for cardiac t-tubule increase with age and myocyte volume to improve measurements of its membrane area and ionic current densities. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 157:40-53. [DOI: 10.1016/j.pbiomolbio.2020.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 06/14/2020] [Accepted: 06/17/2020] [Indexed: 02/02/2023]
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13
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Acker CD, Yan P, Loew LM. Recent progress in optical voltage-sensor technology and applications to cardiac research: from single cells to whole hearts. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 154:3-10. [PMID: 31474387 PMCID: PMC7048644 DOI: 10.1016/j.pbiomolbio.2019.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 07/16/2019] [Accepted: 07/31/2019] [Indexed: 12/25/2022]
Abstract
The first workshop on Novel Optics-based approaches for Cardiac Electrophysiology (NOtiCE) was held in Florence Italy in 2018. Here, we learned how optical approaches have shaped our basic understanding of cardiac electrophysiology and how new technologies and approaches are being developed and validated to advance the field. Several technologies are being developed that may one day allow for new clinical approaches for diagnosing cardiac disorders and possibly intervening to treat human patients. In this review, we discuss several technologies and approaches to optical voltage imaging with voltage-sensitive dyes. We highlight the development and application of fluorinated and long wavelength voltage-sensitive dyes. These optical voltage sensors have now been applied and well validated in several different assays from cultured human stem cell-derived cardiomyocytes to whole hearts in-vivo. Imaging concepts such as dual wavelength ratiometric techniques, which are crucial to maximizing the information from optical sensors by increasing the useful signal and eliminating noise and artifacts, are presented. Finally, novel voltage sensors including photoacoustic voltage-sensitive dyes, their current capabilities and potential advantages, are introduced.
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Affiliation(s)
- Corey D Acker
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, 400 Farmington Avenue, Farmington, CT, 06030, USA.
| | - Ping Yan
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, 400 Farmington Avenue, Farmington, CT, 06030, USA
| | - Leslie M Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, 400 Farmington Avenue, Farmington, CT, 06030, USA
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14
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Spinozzi S, Liu C, Chen Z, Feng W, Zhang L, Ouyang K, Evans SM, Chen J. Nexilin Is Necessary for Maintaining the Transverse-Axial Tubular System in Adult Cardiomyocytes. Circ Heart Fail 2020; 13:e006935. [PMID: 32635769 PMCID: PMC7583668 DOI: 10.1161/circheartfailure.120.006935] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 03/31/2020] [Indexed: 01/28/2023]
Abstract
BACKGROUND NEXN (nexilin) is a protein of the junctional membrane complex required for development of cardiac T-tubules. Global and cardiomyocyte-specific loss of Nexn in mice leads to a rapidly progressive dilated cardiomyopathy and premature death. Therefore, little is known as to the role of NEXN in adult cardiomyocytes. Transverse-axial tubular system remodeling are well-known features in heart failure. Although NEXN is required during development for T-tubule formation, its role, if any, in mature T-tubules remains to be addressed. METHODS Nexn inducible adult cardiomyocyte-specific KO mice were generated. Comprehensive morphological and functional analyses were performed. Heart samples (n>3) were analyzed by molecular, biochemical, and electron microscopy analyses. Isolated single adult cardiomyocytes were analyzed by confocal microscopy, and myocyte shortening/re-lengthening and Ca2+ transient studies were conducted. RESULTS Inducible cardiomyocyte-specific loss of Nexn in adult mice resulted in a dilated cardiomyopathy with reduced cardiac function (13% reduction in percentage fractional shortening; P<0.05). In vivo and in vitro analyses of adult mouse heart samples revealed that NEXN was essential for optimal contraction and calcium handling and was required for maintenance of T-tubule network organization (transverse tubular component in Nexn inducible adult cardiomyocyte-specific KO mice reduced by 40% with respect to controls, P<0.05). CONCLUSIONS Results here reported reveal NEXN to be a pivotal component of adult junctional membrane complexes required for maintenance of transverse-axial tubular architecture. These results demonstrate that NEXN plays an essential role in the adult cardiomyocyte and give further understanding of pathological mechanisms responsible for cardiomyopathy in patients carrying mutations in the NEXN gene.
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MESH Headings
- Age Factors
- Animals
- Calcium/metabolism
- Cardiomyopathy, Dilated/genetics
- Cardiomyopathy, Dilated/metabolism
- Cardiomyopathy, Dilated/physiopathology
- Disease Models, Animal
- Mice
- Mice, Knockout
- Microfilament Proteins/genetics
- Microfilament Proteins/metabolism
- Microfilament Proteins/physiology
- Microtubules/metabolism
- Microtubules/physiology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/physiology
- Ventricular Dysfunction, Left/genetics
- Ventricular Dysfunction, Left/metabolism
- Ventricular Dysfunction, Left/physiopathology
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Affiliation(s)
- Simone Spinozzi
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Canzhao Liu
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Ze’e Chen
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Wei Feng
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Lunfeng Zhang
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Kunfu Ouyang
- Drug Discovery Center, State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Sylvia M. Evans
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Ju Chen
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
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15
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A fundamental evaluation of the electrical properties and function of cardiac transverse tubules. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1867:118502. [PMID: 31269418 DOI: 10.1016/j.bbamcr.2019.06.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 06/07/2019] [Accepted: 06/28/2019] [Indexed: 11/20/2022]
Abstract
This work discusses active and passive electrical properties of transverse (T-)tubules in ventricular cardiomyocytes to understand the physiological roles of T-tubules. T-tubules are invaginations of the lateral membrane that provide a large surface for calcium-handling proteins to facilitate sarcomere shortening. Higher heart rates correlate with higher T-tubular densities in mammalian ventricular cardiomyocytes. We assess ion dynamics in T-tubules and the effects of sodium current in T-tubules on the extracellular potential, which leads to a partial reduction of the sodium current in deep segments of a T-tubule. We moreover reflect on the impact of T-tubules on macroscopic conduction velocity, integrating fundamental principles of action potential propagation and conduction. We also theoretically assess how the conduction velocity is affected by different T-tubular sodium current densities. Lastly, we critically assess literature on ion channel expression to determine whether action potentials can be initiated in T-tubules.
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16
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Studying β 1 and β 2 adrenergic receptor signals in cardiac cells using FRET-based sensors. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 154:30-38. [PMID: 31266653 DOI: 10.1016/j.pbiomolbio.2019.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/10/2019] [Accepted: 06/17/2019] [Indexed: 12/17/2022]
Abstract
Cyclic 3'-5' adenosine monophosphate (cAMP) is a key modulator of cardiac function. Thanks to the sophisticated organization of its pathway in distinct functional units called microdomains, cAMP is involved in the regulation of both inotropy and chronotropy as well as transcription and cardiac death. While visualization of cAMP microdomains can be achieved thanks to cAMP-sensitive FRET-based sensors, the molecular mechanisms through which cAMP-generating stimuli are coupled to distinct functional outcomes are not well understood. One possibility is that each stimulus activates multiple microdomains in order to generate a spatiotemporal code that translates into function. To test this hypothesis here we propose a series of experimental protocols that allow to simultaneously follow cAMP or Protein Kinase A (PKA)-dependent phosphorylation in different subcellular compartments of living cells. We investigate the responses of β Adrenergic receptors (β1AR and β2AR) challenged with selective drugs that enabled us to measure the actions of each receptor independently. At the whole cell level, we used a combination of co-culture with selective βAR stimulation and were able to molecularly separate cardiac fibroblasts from neonatal rat ventricular myocytes based on their cAMP responses. On the other hand, at the subcellular level, these experimental protocols allowed us to dissect the relative weight of β1 and β2 adrenergic receptors on cAMP signalling at the cytosol and outer mitochondrial membrane of NRVMs. We propose that experimental procedures that allow the collection of multiparametric data are necessary in order to understand the molecular mechanisms underlying the coupling between extracellular signals and cellular responses.
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17
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Crocini C, Walker CJ, Anseth KS, Leinwand LA. Three-dimensional encapsulation of adult mouse cardiomyocytes in hydrogels with tunable stiffness. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 154:71-79. [PMID: 31122749 DOI: 10.1016/j.pbiomolbio.2019.04.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 04/25/2019] [Accepted: 04/29/2019] [Indexed: 12/25/2022]
Abstract
Numerous diseases, including those of the heart, are characterized by increased stiffness due to excessive deposition of extracellular matrix proteins. Cardiomyocytes continuously adapt their morphology and function to the mechanical changes of their microenvironment. Because traditional cell culture is conducted on substrates that are many orders of magnitude stiffer than any environment encountered by a cardiomyocyte in health or disease, alternate culture systems are necessary to model these processes in vitro. Here, we employ photo-clickable thiol-ene poly(ethylene glycol) (PEG) hydrogels for three-dimensional cell culture of adult mouse cardiomyocytes. PEG hydrogels serve as versatile biocompatible scaffolds, whose stiffness can be precisely tuned to mimic physiological and pathological microenvironments. Compared to traditional culture, adult cardiomyocytes encapsulated in PEG hydrogels exhibited longer survival and preserved sarcomeric and T-tubular architecture. Culture in PEG hydrogels of varying stiffnesses regulated the subcellular localization of the mechanosensitive transcription factor, YAP, in adult cardiomyocytes, indicating PEG hydrogels offer a versatile platform to study the role of mechanical cues in cardiomyocyte biology.
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Affiliation(s)
- Claudia Crocini
- Department of Molecular Cellular and Developmental Biology, University of Colorado Boulder, CO, 80309, USA; BioFrontiers Institute, University of Colorado Boulder, CO, 80303, USA
| | - Cierra J Walker
- BioFrontiers Institute, University of Colorado Boulder, CO, 80303, USA; Materials Science and Engineering Program, University of Colorado Boulder, CO, 80303, USA
| | - Kristi S Anseth
- Department of Molecular Cellular and Developmental Biology, University of Colorado Boulder, CO, 80309, USA; BioFrontiers Institute, University of Colorado Boulder, CO, 80303, USA; Department of Chemical and Biological Engineering, University of Colorado Boulder, CO, 80303, USA
| | - Leslie A Leinwand
- Department of Molecular Cellular and Developmental Biology, University of Colorado Boulder, CO, 80309, USA; BioFrontiers Institute, University of Colorado Boulder, CO, 80303, USA.
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18
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Crocini C, Ferrantini C, Coppini R, Pavone FS, Poggesi C, Cerbai E, Sacconi L. Letter to the Editor. J Physiol 2019; 597:2965-2966. [PMID: 30924149 DOI: 10.1113/jp278018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- C Crocini
- Department of Molecular, Cellular, and Developmental Biology & BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, United States
| | - C Ferrantini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, 50134, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy
| | - R Coppini
- Division of Pharmacology, Department 'NeuroFarBa', University of Florence, Florence, 50139, Italy
| | - F S Pavone
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, 50019, Italy
| | - C Poggesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, 50134, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy
| | - E Cerbai
- Division of Pharmacology, Department 'NeuroFarBa', University of Florence, Florence, 50139, Italy
| | - L Sacconi
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
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19
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Uchida K, Lopatin AN. Diffusional and Electrical Properties of T-Tubules Are Governed by Their Constrictions and Dilations. Biophys J 2019; 114:437-449. [PMID: 29401441 DOI: 10.1016/j.bpj.2017.11.3742] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 10/27/2017] [Accepted: 11/13/2017] [Indexed: 01/07/2023] Open
Abstract
Cardiac t-tubules (TTs) form a network of complex surface membrane invaginations that is essential for proper excitation-contraction coupling. Although electron and optical microscopy studies provided a wealth of important information about the structure of TTs, assessing their functional properties remains a challenge. In this study, we investigated the diffusional accessibility of TTs in intact isolated adult mouse ventricular myocytes using, to our knowledge, a novel fluorescence-based assay. In this approach, a small part of TTs is first locally filled with fluorescent dextran and then its diffusion out of TTs is monitored after rapid removal of extracellular dextran. In normal cells, diffusion of 3 kDa dextran is characterized by an average time constant of 3.9 ± 1.2 s with the data ranging from 1.8 to 10.5 s. The data are consistent with essentially free diffusion of dextran in TTs although measurable contribution of binding is also evident. TT fluorescence is abolished in cells treated with high concentration of formamide or after hyposmotic stress. Importantly, the assay we use allows for quantitative, repetitive measurements of subtle dynamic changes in TT structure of the same cell that are not possible to observe with other approaches. In particular, dextran diffusion rate decreases two-to-threefold during cell swelling, suggesting significant structural remodeling of TTs. Computer modeling shows that diffusional accessibility and electrical properties of TTs are primarily determined by the constrictions and dilations of individual TTs and that, from a functional perspective, TTs cannot be considered as a network of cylinders of the same average diameter. Constriction/dilation model of cardiac TTs is in a quantitative agreement with previous high-resolution microscopy studies of TT structure and alternative measurements of diffusional and electrical time constants of TTs. The data also show that the apparent electrical length constant of cardiac TTs is likely several-fold smaller than that estimated in earlier studies.
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Affiliation(s)
- Keita Uchida
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Anatoli N Lopatin
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan.
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20
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Scardigli M, Ferrantini C, Crocini C, Pavone FS, Sacconi L. Interplay Between Sub-Cellular Alterations of Calcium Release and T-Tubular Defects in Cardiac Diseases. Front Physiol 2018; 9:1474. [PMID: 30410446 PMCID: PMC6209824 DOI: 10.3389/fphys.2018.01474] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 09/28/2018] [Indexed: 12/19/2022] Open
Abstract
Asynchronous Ca2+ release promotes non-homogeneous myofilament activation, leading to mechanical dysfunction, as well as initiation of propagated calcium waves and arrhythmias. Recent advances in microscopy techniques have allowed for optical recordings of local Ca2+ fluxes and action potentials from multiple sub-cellular domains within cardiac cells with unprecedented spatial and temporal resolution. Since then, sub-cellular local information of the spatio-temporal relationship between Ca2+ release and action potential propagation have been unlocked, providing novel mechanistic insights in cardiac excitation-contraction coupling (ECC). Here, we review the promising perspectives arouse from repeatedly probing Ca2+ release at the same sub-cellular location while simultaneously probing multiple locations at the same time within a single cardiac cell. We also compare the results obtained in three different rodent models of cardiac diseases, highlighting disease-specific mechanisms. Slower local Ca2+ release has been observed in regions with defective action potential conduction in diseased cardiac cells. Moreover, significant increment of Ca2+ variability (both in time and in space) has been found in diseased cardiac cells but does not directly correlate with local electrical defects nor with the degree of structural aberrations of the cellular membrane system, suggesting a role for other players of the ECC machinery. We finally explore exciting opportunities provided by the technology for studying different cardiomyocyte populations, as well as for dissecting the mechanisms responsible for subcellular spatio-temporal variability of Ca2+ release.
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Affiliation(s)
- Marina Scardigli
- National Institute of Optics, National Research Council, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy
| | - Cecilia Ferrantini
- European Laboratory for Non-Linear Spectroscopy, Florence, Italy.,Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Claudia Crocini
- Department of Molecular, Cellular, and Developmental Biology & BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, United States
| | - Francesco S Pavone
- National Institute of Optics, National Research Council, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy.,Department of Physics and Astronomy, University of Florence, Florence, Italy
| | - Leonardo Sacconi
- National Institute of Optics, National Research Council, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy
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21
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Coppini R, Ferrantini C, Mugelli A, Poggesi C, Cerbai E. Altered Ca 2+ and Na + Homeostasis in Human Hypertrophic Cardiomyopathy: Implications for Arrhythmogenesis. Front Physiol 2018; 9:1391. [PMID: 30420810 PMCID: PMC6215954 DOI: 10.3389/fphys.2018.01391] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 09/13/2018] [Indexed: 12/12/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common mendelian heart disease, with a prevalence of 1/500. HCM is a primary cause of sudden death, due to an heightened risk of ventricular tachyarrhythmias that often occur in young asymptomatic patients. HCM can slowly progress toward heart failure, either with preserved or reduced ejection fraction, due to worsening of diastolic function. Accumulation of intra-myocardial fibrosis and replacement scars underlies heart failure progression and represents a substrate for sustained arrhythmias in end-stage patients. However, arrhythmias and mechanical abnormalities may occur in hearts with little or no fibrosis, prompting toward functional pathomechanisms. By studying viable cardiomyocytes and trabeculae isolated from inter-ventricular septum samples of non-failing HCM patients with symptomatic obstruction who underwent myectomy operations, we identified that specific abnormalities of intracellular Ca2+ handling are associated with increased cellular arrhytmogenesis and diastolic dysfunction. In HCM cardiomyocytes, diastolic Ca2+ concentration is increased both in the cytosol and in the sarcoplasmic reticulum and the rate of Ca2+ transient decay is slower, while the amplitude of Ca2+-release is preserved. Ca2+ overload is the consequence of an increased Ca2+ entry via L-type Ca2+-current [due to prolongation the action potential (AP) plateau], combined with a reduced rate of Ca2+-extrusion through the Na+/Ca2+ exchanger [due to increased cytosolic (Na+)] and a lower expression of SERCA. Increased late Na+ current (INaL) plays a major role, as it causes both AP prolongation and Na+ overload. Intracellular Ca2+ overload determines an higher frequency of Ca2+ waves leading to delayed-afterdepolarizations (DADs) and premature contractions, but is also linked with the increased diastolic tension and slower relaxation of HCM myocardium. Sustained increase of intracellular [Ca2+] goes hand-in-hand with the increased activation of Ca2+/calmodulin-dependent protein-kinase-II (CaMKII) and augmented phosphorylation of its targets, including Ca2+ handling proteins. In transgenic HCM mouse models, we found that Ca2+ overload, CaMKII and increased INaL drive myocardial remodeling since the earliest stages of disease and underlie the development of hypertrophy, diastolic dysfunction and the arrhythmogenic substrate. In conclusion, diastolic dysfunction and arrhythmogenesis in human HCM myocardium are driven by functional alterations at cellular and molecular level that may be targets of innovative therapies.
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Affiliation(s)
- Raffaele Coppini
- Department of Neuroscience, Psychology, Drug Sciences and Child Health (NEUROFARBA), University of Florence, Florence, Italy
| | - Cecilia Ferrantini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Alessandro Mugelli
- Department of Neuroscience, Psychology, Drug Sciences and Child Health (NEUROFARBA), University of Florence, Florence, Italy
| | - Corrado Poggesi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Elisabetta Cerbai
- Department of Neuroscience, Psychology, Drug Sciences and Child Health (NEUROFARBA), University of Florence, Florence, Italy
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22
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Brandenburg S, Pawlowitz J, Fakuade FE, Kownatzki-Danger D, Kohl T, Mitronova GY, Scardigli M, Neef J, Schmidt C, Wiedmann F, Pavone FS, Sacconi L, Kutschka I, Sossalla S, Moser T, Voigt N, Lehnart SE. Axial Tubule Junctions Activate Atrial Ca 2+ Release Across Species. Front Physiol 2018; 9:1227. [PMID: 30349482 PMCID: PMC6187065 DOI: 10.3389/fphys.2018.01227] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 08/14/2018] [Indexed: 01/10/2023] Open
Abstract
Rationale: Recently, abundant axial tubule (AT) membrane structures were identified deep inside atrial myocytes (AMs). Upon excitation, ATs rapidly activate intracellular Ca2+ release and sarcomeric contraction through extensive AT junctions, a cell-specific atrial mechanism. While AT junctions with the sarcoplasmic reticulum contain unusually large clusters of ryanodine receptor 2 (RyR2) Ca2+ release channels in mouse AMs, it remains unclear if similar protein networks and membrane structures exist across species, particularly those relevant for atrial disease modeling. Objective: To examine and quantitatively analyze the architecture of AT membrane structures and associated Ca2+ signaling proteins across species from mouse to human. Methods and Results: We developed superresolution microscopy (nanoscopy) strategies for intact live AMs based on a new custom-made photostable cholesterol dye and immunofluorescence imaging of membraneous structures and membrane proteins in fixed tissue sections from human, porcine, and rodent atria. Consistently, in mouse, rat, and rabbit AMs, intact cell-wide tubule networks continuous with the surface membrane were observed, mainly composed of ATs. Moreover, co-immunofluorescence nanoscopy showed L-type Ca2+ channel clusters adjacent to extensive junctional RyR2 clusters at ATs. However, only junctional RyR2 clusters were highly phosphorylated and may thus prime Ca2+ release at ATs, locally for rapid signal amplification. While the density of the integrated L-type Ca2+ current was similar in human and mouse AMs, the intracellular Ca2+ transient showed quantitative differences. Importantly, local intracellular Ca2+ release from AT junctions occurred through instantaneous action potential propagation via transverse tubules (TTs) from the surface membrane. Hence, sparse TTs were sufficient as electrical conduits for rapid activation of Ca2+ release through ATs. Nanoscopy of atrial tissue sections confirmed abundant ATs as the major network component of AMs, particularly in human atrial tissue sections. Conclusion: AT junctions represent a conserved, cell-specific membrane structure for rapid excitation-contraction coupling throughout a representative spectrum of species including human. Since ATs provide the major excitable membrane network component in AMs, a new model of atrial “super-hub” Ca2+ signaling may apply across biomedically relevant species, opening avenues for future investigations about atrial disease mechanisms and therapeutic targeting.
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Affiliation(s)
- Sören Brandenburg
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Jan Pawlowitz
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Funsho E Fakuade
- Heart Research Center Göttingen, Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany
| | - Daniel Kownatzki-Danger
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Tobias Kohl
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Gyuzel Y Mitronova
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Marina Scardigli
- European Laboratory for Non-Linear Spectroscopy and National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy
| | - Jakob Neef
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Constanze Schmidt
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research) partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany.,Heidelberg Center for Heart Rhythm Disorders, University Hospital Heidelberg, Heidelberg, Germany
| | - Felix Wiedmann
- Department of Cardiology, University Hospital Heidelberg, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research) partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany.,Heidelberg Center for Heart Rhythm Disorders, University Hospital Heidelberg, Heidelberg, Germany
| | - Francesco S Pavone
- European Laboratory for Non-Linear Spectroscopy and National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy.,Department of Physics, University of Florence, Florence, Italy
| | - Leonardo Sacconi
- European Laboratory for Non-Linear Spectroscopy and National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy
| | - Ingo Kutschka
- Department of Cardiothoracic and Vascular Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Samuel Sossalla
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Niels Voigt
- Heart Research Center Göttingen, Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research) partner site Göttingen, Göttingen, Germany
| | - Stephan E Lehnart
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research) partner site Göttingen, Göttingen, Germany.,BioMET, The Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, United States
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23
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Denham NC, Pearman CM, Caldwell JL, Madders GWP, Eisner DA, Trafford AW, Dibb KM. Calcium in the Pathophysiology of Atrial Fibrillation and Heart Failure. Front Physiol 2018; 9:1380. [PMID: 30337881 PMCID: PMC6180171 DOI: 10.3389/fphys.2018.01380] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 09/11/2018] [Indexed: 12/20/2022] Open
Abstract
Atrial fibrillation (AF) is commonly associated with heart failure. A bidirectional relationship exists between the two-AF exacerbates heart failure causing a significant increase in heart failure symptoms, admissions to hospital and cardiovascular death, while pathological remodeling of the atria as a result of heart failure increases the risk of AF. A comprehensive understanding of the pathophysiology of AF is essential if we are to break this vicious circle. In this review, the latest evidence will be presented showing a fundamental role for calcium in both the induction and maintenance of AF. After outlining atrial electrophysiology and calcium handling, the role of calcium-dependent afterdepolarizations and atrial repolarization alternans in triggering AF will be considered. The atrial response to rapid stimulation will be discussed, including the short-term protection from calcium overload in the form of calcium signaling silencing and the eventual progression to diastolic calcium leak causing afterdepolarizations and the development of an electrical substrate that perpetuates AF. The role of calcium in the bidirectional relationship between heart failure and AF will then be covered. The effects of heart failure on atrial calcium handling that promote AF will be reviewed, including effects on both atrial myocytes and the pulmonary veins, before the aspects of AF which exacerbate heart failure are discussed. Finally, the limitations of human and animal studies will be explored allowing contextualization of what are sometimes discordant results.
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Affiliation(s)
- Nathan C. Denham
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | | | | | | | | | | | - Katharine M. Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
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24
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Filadi R, Basso E, Lefkimmiatis K, Pozzan T. Beyond Intracellular Signaling: The Ins and Outs of Second Messengers Microdomains. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 981:279-322. [PMID: 29594866 DOI: 10.1007/978-3-319-55858-5_12] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A typical characteristic of eukaryotic cells compared to prokaryotes is represented by the spatial heterogeneity of the different structural and functional components: for example, most of the genetic material is surrounded by a highly specific membrane structure (the nuclear membrane), continuous with, yet largely different from, the endoplasmic reticulum (ER); oxidative phosphorylation is carried out by organelles enclosed by a double membrane, the mitochondria; in addition, distinct domains, enriched in specific proteins, are present in the plasma membrane (PM) of most cells. Less obvious, but now generally accepted, is the notion that even the concentration of small molecules such as second messengers (Ca2+ and cAMP in particular) can be highly heterogeneous within cells. In the case of most organelles, the differences in the luminal levels of second messengers depend either on the existence on their membrane of proteins that allow the accumulation/release of the second messenger (e.g., in the case of Ca2+, pumps, exchangers or channels), or on the synthesis and degradation of the specific molecule within the lumen (the autonomous intramitochondrial cAMP system). It needs stressing that the existence of a surrounding membrane does not necessarily imply the existence of a gradient between the cytosol and the organelle lumen. For example, the nuclear membrane is highly permeable to both Ca2+ and cAMP (nuclear pores are permeable to solutes up to 50 kDa) and differences in [Ca2+] or [cAMP] between cytoplasm and nucleoplasm are not seen in steady state and only very transiently during cell activation. A similar situation has been observed, as far as Ca2+ is concerned, in peroxisomes.
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Affiliation(s)
- Riccardo Filadi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Emy Basso
- Institute of Neuroscience, Padova Section, National Research Council, Padova, Italy
| | - Konstantinos Lefkimmiatis
- Institute of Neuroscience, Padova Section, National Research Council, Padova, Italy
- Venetian Institute of Molecular Medicine, Padova, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padova, Padova, Italy.
- Institute of Neuroscience, Padova Section, National Research Council, Padova, Italy.
- Venetian Institute of Molecular Medicine, Padova, Italy.
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25
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Scardigli M, Müllenbroich C, Margoni E, Cannazzaro S, Crocini C, Ferrantini C, Coppini R, Yan P, Loew LM, Campione M, Bocchi L, Giulietti D, Cerbai E, Poggesi C, Bub G, Pavone FS, Sacconi L. Real-time optical manipulation of cardiac conduction in intact hearts. J Physiol 2018; 596:3841-3858. [PMID: 29989169 PMCID: PMC6117584 DOI: 10.1113/jp276283] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/05/2018] [Indexed: 11/28/2022] Open
Abstract
Key points Although optogenetics has clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies lack the capability to react acutely to ongoing cardiac wave dynamics. Here, we developed an all‐optical platform to monitor and control electrical activity in real‐time. The methodology was applied to restore normal electrical activity after atrioventricular block and to manipulate the intraventricular propagation of the electrical wavefront. The closed‐loop approach was also applied to simulate a re‐entrant circuit across the ventricle. The development of this innovative optical methodology provides the first proof‐of‐concept that a real‐time all‐optical stimulation can control cardiac rhythm in normal and abnormal conditions.
Abstract Optogenetics has provided new insights in cardiovascular research, leading to new methods for cardiac pacing, resynchronization therapy and cardioversion. Although these interventions have clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies do not take into account cardiac wave dynamics in real time. Here, we developed an all‐optical platform complemented by integrated, newly developed software to monitor and control electrical activity in intact mouse hearts. The system combined a wide‐field mesoscope with a digital projector for optogenetic activation. Cardiac functionality could be manipulated either in free‐run mode with submillisecond temporal resolution or in a closed‐loop fashion: a tailored hardware and software platform allowed real‐time intervention capable of reacting within 2 ms. The methodology was applied to restore normal electrical activity after atrioventricular block, by triggering the ventricle in response to optically mapped atrial activity with appropriate timing. Real‐time intraventricular manipulation of the propagating electrical wavefront was also demonstrated, opening the prospect for real‐time resynchronization therapy and cardiac defibrillation. Furthermore, the closed‐loop approach was applied to simulate a re‐entrant circuit across the ventricle demonstrating the capability of our system to manipulate heart conduction with high versatility even in arrhythmogenic conditions. The development of this innovative optical methodology provides the first proof‐of‐concept that a real‐time optically based stimulation can control cardiac rhythm in normal and abnormal conditions, promising a new approach for the investigation of the (patho)physiology of the heart. Although optogenetics has clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies lack the capability to react acutely to ongoing cardiac wave dynamics. Here, we developed an all‐optical platform to monitor and control electrical activity in real‐time. The methodology was applied to restore normal electrical activity after atrioventricular block and to manipulate the intraventricular propagation of the electrical wavefront. The closed‐loop approach was also applied to simulate a re‐entrant circuit across the ventricle. The development of this innovative optical methodology provides the first proof‐of‐concept that a real‐time all‐optical stimulation can control cardiac rhythm in normal and abnormal conditions.
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Affiliation(s)
- M Scardigli
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - C Müllenbroich
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - E Margoni
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,Department of Physics, University of Pisa, Pisa, 56127, Italy
| | - S Cannazzaro
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - C Crocini
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - C Ferrantini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, 50134, Italy
| | - R Coppini
- Division of Pharmacology, Department 'NeuroFarBa', University of Florence, Florence, 50139, Italy
| | - P Yan
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - L M Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - M Campione
- Neuroscience Institute, National Research Council, Padova, 35121, Italy.,Department of Biomedical Sciences, Univercity ot Padua, Padua, 35121, Italy
| | - L Bocchi
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,Department of Information Engineering, University of Florence, Via S. Marta 3, Florence, 50139, Italy
| | - D Giulietti
- National Institute of Optics, National Research Council, Florence, 50125, Italy.,Department of Physics, University of Pisa, Pisa, 56127, Italy
| | - E Cerbai
- Division of Pharmacology, Department 'NeuroFarBa', University of Florence, Florence, 50139, Italy
| | - C Poggesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, 50134, Italy
| | - G Bub
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - F S Pavone
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy.,Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, 50019, Italy
| | - L Sacconi
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
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26
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Crossman DJ, Shen X, Jüllig M, Munro M, Hou Y, Middleditch M, Shrestha D, Li A, Lal S, Dos Remedios CG, Baddeley D, Ruygrok PN, Soeller C. Increased collagen within the transverse tubules in human heart failure. Cardiovasc Res 2018; 113:879-891. [PMID: 28444133 DOI: 10.1093/cvr/cvx055] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 03/20/2017] [Indexed: 12/22/2022] Open
Abstract
Aims In heart failure transverse-tubule (t-tubule) remodelling disrupts calcium release, and contraction. T-tubules in human failing hearts exhibit increased labelling by wheat germ agglutinin (WGA), a lectin that binds to the dystrophin-associated glycoprotein complex. We hypothesized changes in this complex may explain the increased WGA labelling and contribute to t-tubule remodelling in the failing human heart. In this study we sought to identify the molecules responsible for this increased WGA labelling. Methods and results Confocal and super-resolution fluorescence microscopy and proteomic analyses were used to quantify left ventricle samples from healthy donors and patients with idiopathic dilated cardiomyopathy (IDCM). Confocal microscopy demonstrated both WGA and dystrophin were located at t-tubules. Super-resolution microscopy revealed that WGA labelling of t-tubules is largely located within the lumen while dystrophin was restricted to near the sarcolemma. Western blots probed with WGA reveal a 5.7-fold increase in a 140 kDa band in IDCM. Mass spectrometry identified this band as type VI collagen (Col-VI) comprised of α1(VI), α2(VI), and α3(VI) chains. Pertinently, mutations in Col-VI cause muscular dystrophy. Western blotting identified a 2.4-fold increased expression and 3.2-fold increased WGA binding of Col-VI in IDCM. Confocal images showed that Col-VI is located in the t-tubules and that their diameter increased in the IDCM samples. Super-resolution imaging revealed Col-VI was restricted to the t-tubule lumen where increases were associated with displacement in the sarcolemma as identified from dystrophin labelling. Samples were also labelled for type I, III, and IV collagen. Both confocal and super-resolution imaging identified that these collagens were also present within t-tubule lumen. Conclusion Increased expression and labelling of collagen in IDCM samples indicates fibrosis may contribute to t-tubule remodelling in human heart failure.
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Affiliation(s)
- David J Crossman
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Xin Shen
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Mia Jüllig
- School of Biological Sciences, University of Auckland, 3a Symonds Street, Auckland 1010, New Zealand
| | - Michelle Munro
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Yufeng Hou
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Martin Middleditch
- School of Biological Sciences, University of Auckland, 3a Symonds Street, Auckland 1010, New Zealand
| | - Darshan Shrestha
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Amy Li
- Bosch Institute, University of Sydney, Fisher Road Sydney, NSW 2006, Australia
| | - Sean Lal
- Bosch Institute, University of Sydney, Fisher Road Sydney, NSW 2006, Australia
| | | | - David Baddeley
- Department of Cell Biology, Yale University, West Campus, 300 Heffernan Drive, Haven, CT 06515, USA
| | - Peter N Ruygrok
- Department of Cardiology, Auckland City Hospital, Auckland 1042, New Zealand
| | - Christian Soeller
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland 1023, New Zealand.,Living Systems Institute and Biomedical Physics, University of Exeter, Stocker Road, Exeter EX4QL, UK
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27
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Broyles CN, Robinson P, Daniels MJ. Fluorescent, Bioluminescent, and Optogenetic Approaches to Study Excitable Physiology in the Single Cardiomyocyte. Cells 2018; 7:cells7060051. [PMID: 29857560 PMCID: PMC6028913 DOI: 10.3390/cells7060051] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 05/22/2018] [Accepted: 05/30/2018] [Indexed: 12/11/2022] Open
Abstract
This review briefly summarizes the single cell application of classical chemical dyes used to visualize cardiomyocyte physiology and their undesirable toxicities which have the potential to confound experimental observations. We will discuss, in detail, the more recent iterative development of fluorescent and bioluminescent protein-based indicators and their emerging application to cardiomyocytes. We will discuss the integration of optical control strategies (optogenetics) to augment the standard imaging approach. This will be done in the context of potential applications, and barriers, of these technologies to disease modelling, drug toxicity, and drug discovery efforts at the single-cell scale.
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Affiliation(s)
- Connor N Broyles
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK.
- BHF Centre of Research Excellence, University of Oxford, Oxford OX3 9DU, UK.
| | - Paul Robinson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK.
- BHF Centre of Research Excellence, University of Oxford, Oxford OX3 9DU, UK.
| | - Matthew J Daniels
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK.
- BHF Centre of Research Excellence, University of Oxford, Oxford OX3 9DU, UK.
- Department of Cardiology, Oxford University NHS Hospitals Trust, Oxford OX3 9DU, UK.
- BHF Centre of Regenerative Medicine, University of Oxford, Oxford OX3 9DU, UK.
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Mihogaoka 8-1, Ibaraki, 567-0047 Osaka, Japan.
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Highly variable contractile performance correlates with myocyte content in trabeculae from failing human hearts. Sci Rep 2018; 8:2957. [PMID: 29440728 PMCID: PMC5811450 DOI: 10.1038/s41598-018-21199-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 01/16/2018] [Indexed: 12/24/2022] Open
Abstract
Heart failure (HF) is defined by compromised contractile function and is associated with changes in excitation-contraction (EC) coupling and cardiomyocyte organisation. Tissue level changes often include fibrosis, while changes within cardiomyocytes often affect structures critical to EC coupling, including the ryanodine receptor (RyR), the associated protein junctophilin-2 (JPH2) and the transverse tubular system architecture. Using a novel approach, we aimed to directly correlate the influence of structural alterations with force development in ventricular trabeculae from failing human hearts. Trabeculae were excised from explanted human hearts in end-stage failure and immediately subjected to force measurements. Following functional experiments, each trabecula was fixed, sectioned and immuno-stained for structural investigations. Peak stress was highly variable between trabeculae from both within and between failing hearts and was strongly correlated with the cross-sectional area occupied by myocytes (MCSA), rather than total trabecula cross-sectional area. At the cellular level, myocytes exhibited extensive microtubule densification which was linked via JPH2 to time-to-peak stress. Trabeculae fractional MCSA variability was much higher than that in adjacent free wall samples. Together, these findings identify several structural parameters implicated in functional impairment in human HF and highlight the structural variability of ventricular trabeculae which should be considered when interpreting functional data.
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Smith CER, Trafford AW, Caldwell JL, Dibb KM. Physiology and patho-physiology of the cardiac transverse tubular system. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2017.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Reply to Entcheva: The impact of T-tubules on action potential propagation in cardiac tissue. Proc Natl Acad Sci U S A 2018; 115:E562-E563. [PMID: 29305385 DOI: 10.1073/pnas.1720253115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Zhang C, Chen B, Wang Y, Guo A, Tang Y, Khataei T, Shi Y, Kutschke WJ, Zimmerman K, Weiss RM, Liu J, Benson CJ, Hong J, Ma J, Song LS. MG53 is dispensable for T-tubule maturation but critical for maintaining T-tubule integrity following cardiac stress. J Mol Cell Cardiol 2017; 112:123-130. [PMID: 28822805 DOI: 10.1016/j.yjmcc.2017.08.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/13/2017] [Accepted: 08/14/2017] [Indexed: 01/28/2023]
Abstract
The cardiac transverse (T)-tubule membrane system is the safeguard for cardiac function and undergoes dramatic remodeling in response to cardiac stress. However, the mechanism by which cardiomyocytes repair damaged T-tubule network remains unclear. In the present study, we tested the hypothesis that MG53, a muscle-specific membrane repair protein, antagonizes T-tubule damage to protect against maladaptive remodeling and thereby loss of excitation-contraction coupling and cardiac function. Using MG53-knockout (MG53-KO) mice, we first established that deficiency of MG53 had no impact on maturation of the T-tubule network in developing hearts. Additionally, MG53 ablation did not influence T-tubule integrity in unstressed adult hearts as late as 10months of age. Following left ventricular pressure overload-induced cardiac stress, MG53 protein levels were increased by approximately three-fold in wild-type mice, indicating that pathological stress induces a significant upregulation of MG53. MG53-deficient mice had worsened T-tubule disruption and pronounced dysregulation of Ca2+ handling properties, including decreased Ca2+ transient amplitude and prolonged time to peak and decay. Moreover, MG53 deficiency exacerbated cardiac hypertrophy and dysfunction and decreased survival following cardiac stress. Our data suggest MG53 is not required for T-tubule development and maintenance in normal physiology. However, MG53 is essential to preserve T-tubule integrity and thereby Ca2+ handling properties and cardiac function under pathological cardiac stress.
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Affiliation(s)
- Caimei Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Biyi Chen
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Yihui Wang
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA; Shanghai First People's Hospital, Shanghai Jiaotong University, Shanghai 200080, China
| | - Ang Guo
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Yiqun Tang
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA; Department of Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Tahsin Khataei
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Yun Shi
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - William J Kutschke
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Kathy Zimmerman
- Department of Veterans Affairs Medical Center, Iowa City, IA 52242, USA
| | - Robert M Weiss
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Jie Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen 518060, China
| | - Christopher J Benson
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA; Department of Veterans Affairs Medical Center, Iowa City, IA 52242, USA
| | - Jiang Hong
- Shanghai First People's Hospital, Shanghai Jiaotong University, Shanghai 200080, China
| | - Jianjie Ma
- Department of Surgery, Ohio State University Medical Center, Columbus, OH 43212, USA
| | - Long-Sheng Song
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA; Department of Veterans Affairs Medical Center, Iowa City, IA 52242, USA.
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Seidel T, Sankarankutty AC, Sachse FB. Remodeling of the transverse tubular system after myocardial infarction in rabbit correlates with local fibrosis: A potential role of biomechanics. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:302-314. [PMID: 28709857 DOI: 10.1016/j.pbiomolbio.2017.07.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 07/07/2017] [Accepted: 07/10/2017] [Indexed: 02/03/2023]
Abstract
The transverse tubular system (t-system) of ventricular cardiomyocytes is essential for efficient excitation-contraction coupling. In cardiac diseases, such as heart failure, remodeling of the t-system contributes to reduced cardiac contractility. However, mechanisms of t-system remodeling are incompletely understood. Prior studies suggested an association with altered cardiac biomechanics and gene expression in disease. Since fibrosis may alter tissue biomechanics, we investigated the local microscopic association of t-system remodeling with fibrosis in a rabbit model of myocardial infarction (MI). Biopsies were taken from the MI border zone of 6 infarcted hearts and from 6 control hearts. Using confocal microscopy and automated image analysis, we quantified t-system integrity (ITT) and the local fraction of extracellular matrix (fECM). In control, fECM was 18 ± 0.3%. ITT was high and homogeneous (0.07 ± 0.006), and did not correlate with fECM (R2 = 0.05 ± 0.02). The MI border zone exhibited increased fECM within 3 mm from the infarct scar (30 ± 3.5%, p < 0.01 vs control), indicating fibrosis. Myocytes in the MI border zone exhibited significant t-system remodeling, with dilated, sheet-like components, resulting in low ITT (0.03 ± 0.008, p < 0.001 vs control). While both fECM and t-system remodeling decreased with infarct distance, ITT correlated better with decreasing fECM (R2 = 0.44) than with infarct distance (R2 = 0.24, p < 0.05). Our results show that t-system remodeling in the rabbit MI border zone resembles a phenotype previously described in human heart failure. T-system remodeling correlated with the amount of local fibrosis, which is known to stiffen cardiac tissue, but was not found in regions without fibrosis. Thus, locally altered tissue mechanics may contribute to t-system remodeling.
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Affiliation(s)
- T Seidel
- Institute for Cellular and Molecular Physiology, University of Erlangen-Nuremberg, Erlangen, Germany; Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, USA.
| | - A C Sankarankutty
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, USA; Department of Bioengineering, University of Utah, Salt Lake City, USA
| | - F B Sachse
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, USA; Department of Bioengineering, University of Utah, Salt Lake City, USA.
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Crossman DJ, Jayasinghe ID, Soeller C. Transverse tubule remodelling: a cellular pathology driven by both sides of the plasmalemma? Biophys Rev 2017; 9:919-929. [PMID: 28695473 DOI: 10.1007/s12551-017-0273-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/06/2017] [Indexed: 01/10/2023] Open
Abstract
Transverse (t)-tubules are invaginations of the plasma membrane that form a complex network of ducts, 200-400 nm in diameter depending on the animal species, that penetrates deep within the cardiac myocyte, where they facilitate a fast and synchronous contraction across the entire cell volume. There is now a large body of evidence in animal models and humans demonstrating that pathological distortion of the t-tubule structure has a causative role in the loss of myocyte contractility that underpins many forms of heart failure. Investigations into the molecular mechanisms of pathological t-tubule remodelling to date have focused on proteins residing in the intracellular aspect of t-tubule membrane that form linkages between the membrane and myocyte cytoskeleton. In this review, we shed light on the mechanisms of t-tubule remodelling which are not limited to the intracellular side. Our recent data have demonstrated that collagen is an integral part of the t-tubule network and that it increases within the tubules in heart failure, suggesting that a fibrotic mechanism could drive cardiac junctional remodelling. We examine the evidence that the linkages between the extracellular matrix, t-tubule membrane and cellular cytoskeleton should be considered as a whole when investigating the mechanisms of t-tubule pathology in the failing heart.
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Affiliation(s)
- David J Crossman
- Department of Physiology, University of Auckland, Auckland, New Zealand.
| | | | - Christian Soeller
- Department of Physiology, University of Auckland, Auckland, New Zealand
- Biomedical Physics, University of Exeter, Exeter, UK
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Coppini R, Mazzoni L, Ferrantini C, Gentile F, Pioner JM, Laurino A, Santini L, Bargelli V, Rotellini M, Bartolucci G, Crocini C, Sacconi L, Tesi C, Belardinelli L, Tardiff J, Mugelli A, Olivotto I, Cerbai E, Poggesi C. Ranolazine Prevents Phenotype Development in a Mouse Model of Hypertrophic Cardiomyopathy. Circ Heart Fail 2017; 10:CIRCHEARTFAILURE.116.003565. [PMID: 28255011 DOI: 10.1161/circheartfailure.116.003565] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 01/30/2017] [Indexed: 01/04/2023]
Abstract
BACKGROUND Current therapies are ineffective in preventing the development of cardiac phenotype in young carriers of mutations associated with hypertrophic cardiomyopathy (HCM). Ranolazine, a late Na+ current blocker, reduced the electromechanical dysfunction of human HCM myocardium in vitro. METHODS AND RESULTS To test whether long-term treatment prevents cardiomyopathy in vivo, transgenic mice harboring the R92Q troponin-T mutation and wild-type littermates received an oral lifelong treatment with ranolazine and were compared with age-matched vehicle-treated animals. In 12-months-old male R92Q mice, ranolazine at therapeutic plasma concentrations prevented the development of HCM-related cardiac phenotype, including thickening of the interventricular septum, left ventricular volume reduction, left ventricular hypercontractility, diastolic dysfunction, left-atrial enlargement and left ventricular fibrosis, as evaluated in vivo using echocardiography and magnetic resonance. Left ventricular cardiomyocytes from vehicle-treated R92Q mice showed marked excitation-contraction coupling abnormalities, including increased diastolic [Ca2+] and Ca2+ waves, whereas cells from treated mutants were undistinguishable from those from wild-type mice. Intact trabeculae from vehicle-treated mutants displayed inotropic insufficiency, increased diastolic tension, and premature contractions; ranolazine treatment counteracted the development of myocardial mechanical abnormalities. In mutant myocytes, ranolazine inhibited the enhanced late Na+ current and reduced intracellular [Na+] and diastolic [Ca2+], ultimately preventing the pathological increase of calmodulin kinase activity in treated mice. CONCLUSIONS Owing to the sustained reduction of intracellular Ca2+ and calmodulin kinase activity, ranolazine prevented the development of morphological and functional cardiac phenotype in mice carrying a clinically relevant HCM-related mutation. Pharmacological inhibitors of late Na+ current are promising candidates for an early preventive therapy in young phenotype-negative subjects carrying high-risk HCM-related mutations.
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Affiliation(s)
- Raffaele Coppini
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.).
| | - Luca Mazzoni
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Cecilia Ferrantini
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Francesca Gentile
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Josè Manuel Pioner
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Annunziatina Laurino
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Lorenzo Santini
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Valentina Bargelli
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Matteo Rotellini
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Gianluca Bartolucci
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Claudia Crocini
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Leonardo Sacconi
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Chiara Tesi
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Luiz Belardinelli
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Jil Tardiff
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Alessandro Mugelli
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Iacopo Olivotto
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Elisabetta Cerbai
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
| | - Corrado Poggesi
- From the Department NeuroFarBa (R.C., L.M., T.L., L. Santini, V.B., G.B., A.M., E.C.) and Department of Experimental and Clinical Medicine (C.F., F.G., J.M.P., C.T., C.P.), University of Florence, Italy; European Laboratory for Non-linear Spectroscopy (LENS), University of Florence & National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy (C.C., L. Sacconi); Gilead Sciences Inc., Foster City, CA (L.B.); Department of Cellular and Molecular Medicine University of Arizona at Tucson, USA (J.T.); and Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy (M.R., I.O.)
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Quantitative assessment of passive electrical properties of the cardiac T-tubular system by FRAP microscopy. Proc Natl Acad Sci U S A 2017; 114:5737-5742. [PMID: 28507142 DOI: 10.1073/pnas.1702188114] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Well-coordinated activation of all cardiomyocytes must occur on every heartbeat. At the cell level, a complex network of sarcolemmal invaginations, called the transverse-axial tubular system (TATS), propagates membrane potential changes to the cell core, ensuring synchronous and uniform excitation-contraction coupling. Although myocardial conduction of excitation has been widely described, the electrical properties of the TATS remain mostly unknown. Here, we exploit the formal analogy between diffusion and electrical conductivity to link the latter with the diffusional properties of TATS. Fluorescence recovery after photobleaching (FRAP) microscopy is used to probe the diffusion properties of TATS in isolated rat cardiomyocytes: A fluorescent dextran inside TATS lumen is photobleached, and signal recovery by diffusion of unbleached dextran from the extracellular space is monitored. We designed a mathematical model to correlate the time constant of fluorescence recovery with the apparent diffusion coefficient of the fluorescent molecules. Then, apparent diffusion is linked to electrical conductivity and used to evaluate the efficiency of the passive spread of membrane depolarization along TATS. The method is first validated in cells where most TATS elements are acutely detached by osmotic shock and then applied to probe TATS electrical conductivity in failing heart cells. We find that acute and pathological tubular remodeling significantly affect TATS electrical conductivity. This may explain the occurrence of defects in action potential propagation at the level of single T-tubules, recently observed in diseased cardiomyocytes.
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Crocini C, Ferrantini C, Pavone FS, Sacconi L. Optogenetics gets to the heart: A guiding light beyond defibrillation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:132-139. [PMID: 28506694 DOI: 10.1016/j.pbiomolbio.2017.05.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 05/10/2017] [Accepted: 05/11/2017] [Indexed: 01/01/2023]
Abstract
Optogenetics provides a tool for controlling the electrical activity of excitable cells by means of the interaction of light with light-gated ion channels. Despite the fact that optogenetics has been intensively utilized in the neurosciences, it has been more rarely employed as an instrument for studying cardiac pathophysiology. However, the advantages of optical approaches to perturb cardiac electrical activity are numerous, especially when the spatio-temporal qualities of light are utterly exploited. Here, we review the main breakthroughs employing optogenetics to perturb cardiac pathophysiology and attempt a comparison of methods and procedures that have employed optogenetics in the heart. We particularly focus on light-based defibrillation strategies that represent one of the latest achievements in this field. We highlight the important role of advanced optical methods for detecting and stimulating electrical activity for optimizing defibrillation strategies and, more generally, for dissecting novel insights in cardiac physiology. Finally, we discuss the main future perspectives that we envision for optogenetics in the heart, both in terms of translational applications and for addressing fundamental questions of cardiac function.
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Affiliation(s)
- Claudia Crocini
- European Laboratory for Non Linear Spectroscopy (LENS), Via Nello Carrara, 1 - 50019 Sesto Fiorentino, FI, Italy; National Institute of Optic (CNR-INO), Via Nello Carrara, 1 - 50019 Sesto Fiorentino, Italy.
| | - Cecilia Ferrantini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Francesco S Pavone
- European Laboratory for Non Linear Spectroscopy (LENS), Via Nello Carrara, 1 - 50019 Sesto Fiorentino, FI, Italy; National Institute of Optic (CNR-INO), Via Nello Carrara, 1 - 50019 Sesto Fiorentino, Italy; Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Leonardo Sacconi
- European Laboratory for Non Linear Spectroscopy (LENS), Via Nello Carrara, 1 - 50019 Sesto Fiorentino, FI, Italy; National Institute of Optic (CNR-INO), Via Nello Carrara, 1 - 50019 Sesto Fiorentino, Italy
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37
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Pinali C, Malik N, Davenport JB, Allan LJ, Murfitt L, Iqbal MM, Boyett MR, Wright EJ, Walker R, Zhang Y, Dobryznski H, Holt CM, Kitmitto A. Post-Myocardial Infarction T-tubules Form Enlarged Branched Structures With Dysregulation of Junctophilin-2 and Bridging Integrator 1 (BIN-1). J Am Heart Assoc 2017; 6:e004834. [PMID: 28473402 PMCID: PMC5524063 DOI: 10.1161/jaha.116.004834] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 01/26/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Heart failure is a common secondary complication following a myocardial infarction (MI), characterized by impaired cardiac contraction and t-tubule (t-t) loss. However, post-MI nano-scale morphological changes to the remaining t-ts are poorly understood. METHOD AND RESULTS We utilized a porcine model of MI, using a nonlethal microembolization method to generate controlled microinfarcts. Using serial block face scanning electron microscopy, we report that post-MI, after mild left-ventricular dysfunction has developed, t-ts are not only lost in the peri-infarct region, but also the remnant t-ts form enlarged, highly branched disordered structures, containing a dense intricate inner membrane. Biochemical and proteomics analyses showed that the calcium release channel, ryanodine receptor 2 (RyR2), abundance is unchanged, but junctophilin-2 (JP2), important for maintaining t-t trajectory, is depressed (-0.5×) in keeping with the t-ts being disorganized. However, immunolabeling shows that populations of RyR2 and JP2 remain associated with the remodeled t-ts. The bridging integrator 1 protein (BIN-1), a regulator of tubulogensis, is upregulated (+5.4×), consistent with an overdeveloped internal membrane system, a feature not present in control t-ts. Importantly, we have determined that t-ts, in the remote region, are narrowed and also contain dense membrane folds (BIN-1 is up-regulated +3.4×), whereas the t-ts have a radial organization comparable to control JP2 is upregulated +1.7×. CONCLUSIONS This study reveals previously unidentified remodeling of the t-t nano-architecture in the post-MI heart that extends to the remote region. Our findings highlight that targeting JP2 may be beneficial for preserving the orientation of the t-ts, attenuating the development of hypocontractility post-MI.
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Affiliation(s)
- Christian Pinali
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Nadim Malik
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - J Bernard Davenport
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Laurence J Allan
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Lucy Murfitt
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Mohammad M Iqbal
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Mark R Boyett
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Elizabeth J Wright
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Rachel Walker
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Yu Zhang
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Halina Dobryznski
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Cathy M Holt
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Ashraf Kitmitto
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
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38
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Liu W, Chia SH, Chung HY, Greinert R, Kärtner FX, Chang G. Energetic ultrafast fiber laser sources tunable in 1030-1215 nm for deep tissue multi-photon microscopy. OPTICS EXPRESS 2017; 25:6822-6831. [PMID: 28381024 DOI: 10.1364/oe.25.006822] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We demonstrate an energy scalable approach to implement ultrafast fiber laser sources suitable for deep tissue multi-photon microscopy imaging. Enabled by fiber-optic nonlinearities (dominated by self-phase modulation), these unique ultrafast sources produce nearly transform-limited pulses of 50-90 fs in duration with the center wavelength tunable in the wavelength range of 1030-1215 nm. The resulting pulse energy can be scaled up to 20 nJ by optimizing fiber dispersion, shortening fiber length, and using large-mode-area fibers. We applied such an energetic source to a proof-of-principle study of ex vivo human skin based on harmonics (i.e., second-harmonic generation and third-harmonic generation) imaging. This new type of fiber-format energetic ultrafast source provides a robust solution for multiphoton microscopy applications.
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39
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Abstract
Unique to striated muscle cells, transverse tubules (t-tubules) are membrane organelles that consist of sarcolemma penetrating into the myocyte interior, forming a highly branched and interconnected network. Mature t-tubule networks are found in mammalian ventricular cardiomyocytes, with the transverse components of t-tubules occurring near sarcomeric z-discs. Cardiac t-tubules contain membrane microdomains enriched with ion channels and signaling molecules. The microdomains serve as key signaling hubs in regulation of cardiomyocyte function. Dyad microdomains formed at the junctional contact between t-tubule membrane and neighboring sarcoplasmic reticulum are critical in calcium signaling and excitation-contraction coupling necessary for beat-to-beat heart contraction. In this review, we provide an overview of the current knowledge in gross morphology and structure, membrane and protein composition, and function of the cardiac t-tubule network. We also review in detail current knowledge on the formation of functional membrane subdomains within t-tubules, with a particular focus on the cardiac dyad microdomain. Lastly, we discuss the dynamic nature of t-tubules including membrane turnover, trafficking of transmembrane proteins, and the life cycles of membrane subdomains such as the cardiac BIN1-microdomain, as well as t-tubule remodeling and alteration in diseased hearts. Understanding cardiac t-tubule biology in normal and failing hearts is providing novel diagnostic and therapeutic opportunities to better treat patients with failing hearts.
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Affiliation(s)
- TingTing Hong
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California; and Department of Medicine, University of California Los Angeles, Los Angeles, California
| | - Robin M Shaw
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California; and Department of Medicine, University of California Los Angeles, Los Angeles, California
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40
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Crocini C, Ferrantini C, Coppini R, Sacconi L. Electrical defects of the transverse-axial tubular system in cardiac diseases. J Physiol 2017; 595:3815-3822. [PMID: 27981580 PMCID: PMC5471422 DOI: 10.1113/jp273042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/21/2016] [Indexed: 01/20/2023] Open
Abstract
Electrical excitability is an essential feature of cardiomyocytes and the homogenous propagation of the action potential is guaranteed by a complex network of membrane invaginations called the transverse-axial tubular system (TATS). TATS structural remodelling is a hallmark of cardiac diseases and we demonstrated that this can be accompanied by electrical defects at single T-tubular level. Using a random-access multi-photon (RAMP) microscope, we found that pathological T-tubules can fail to conduct action potentials, which delays local Ca2+ release. Although the underlying causes for T-tubular electrical failure are still unknown, our findings suggest that they are likely to be related to local ultrastructural alterations. Here, we first review the experimental approach that allowed us to observe and dissect the consequences of TATS electrical dysfunction and then propose two different strategies to unveil the reasons for T-tubular electrical failures. The first strategy consists in a correlative approach, in which the failing T-tubule identified with the RAMP microscope is then imaged with electron microscopy. The second approach exploits the diffusion of molecules within TATS to gain insights into the local TATS structure, even without a thorough reconstruction of the tubular network. Although challenging, the local electrical failure occurring at single T-tubules is a fundamental question that needs to be addressed and could provide novel insights in cardiac pathophysiology.
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Affiliation(s)
- Claudia Crocini
- European Laboratory for Non-Linear Spectroscopy, 50019, Sesto Fiorentino, Italy.,National Institute of Optics, National Research Council, 50125, Florence, Italy
| | - Cecilia Ferrantini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, 50134, Florence, Italy
| | - Raffaele Coppini
- Division of Pharmacology, Department 'NeuroFarBa', University of Florence, 50139, Florence, Italy
| | - Leonardo Sacconi
- European Laboratory for Non-Linear Spectroscopy, 50019, Sesto Fiorentino, Italy.,National Institute of Optics, National Research Council, 50125, Florence, Italy
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41
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Early transverse tubule development begins in utero in the sheep heart. J Muscle Res Cell Motil 2017; 37:195-202. [PMID: 28062939 DOI: 10.1007/s10974-016-9462-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 12/10/2016] [Indexed: 10/20/2022]
Abstract
The ventricular cardiomyocytes of adult mammals contain invaginations of the plasma membrane known as transverse (t)-tubules. These regular structures are essential for the synchronisation of excitation-contraction (EC) coupling throughout the cell, which is a vital process for cardiac function. T-tubules form a close association with the sarcoplasmic reticulum (SR) to form junctions, where several key proteins involved in EC coupling are localised, including the SR calcium release channels-the ryanodine receptors (RyR). The lipophilic SR protein junctophilin-2 (JPH2) has been implicated in the development of both the junctions and t-tubules. Several studies have identified that t-tubules develop only postnatally in rodents, while historical electron microscopy data indicate that this is not the case in larger mammals, including humans. We have performed, to our knowledge, the first fluorescent, target-specific study to characterise t-tubule development in the large mammalian fetal heart, focussing on the sheep. T-tubules were present in fetal sheep hearts from 114 days gestation (with term being 145 days), with occurrence progressively increasing with gestational age, and further maturation after birth. This was accompanied by an increasing intracellular localisation of JPH2, which progressively increased its association with RyR within the cardiomyocytes as they undergo hypertrophy. These findings indicate that large mammalian hearts exhibit a significantly different temporal pattern of development compared to that of the rodent. Our findings have potential implications for human cardiac development, including the future investigation of congenital heart disease.
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42
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Khater NA, Selim SA, Abd El-Baset SA, Abd El Hameed SH. Therapeutic effect of mesenchymal stem cells on experimentally induced hypertensive cardiomyopathy in adult albino rats. Ultrastruct Pathol 2016; 41:36-50. [PMID: 28029272 DOI: 10.1080/01913123.2016.1260080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Hypertensive heart diseases affect millions of people worldwide. We aimed to investigate the hypertensive left ventricular histological changes and assess the effectiveness of bone marrow derived mesenchymal stem cells (MSCs) therapy in the treatment of hypertensive cardiomyopathy. Adult male albino rats were assigned into two groups: group I (control), group II (Experimental) subdivided into subgroup IIa (hypertensive) and subgroup IIb (stem cell therapy). Left ventricles (LVs) were processed for light and electron microscope. Mallory's trichrome and immunostaining for caspase-3 and desmin were carried out. Hypertension caused left ventricular histological and immunohistochemical changes that had been effectively improved by MSCs therapy.
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Affiliation(s)
- Nariman A Khater
- a Department of Histology and Cell Biology, Faculty of Medicine , Zagazig University , Zagazig , Egypt
| | - Sally A Selim
- a Department of Histology and Cell Biology, Faculty of Medicine , Zagazig University , Zagazig , Egypt
| | - Samia A Abd El-Baset
- a Department of Histology and Cell Biology, Faculty of Medicine , Zagazig University , Zagazig , Egypt
| | - Samar H Abd El Hameed
- a Department of Histology and Cell Biology, Faculty of Medicine , Zagazig University , Zagazig , Egypt
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43
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Optogenetics design of mechanistically-based stimulation patterns for cardiac defibrillation. Sci Rep 2016; 6:35628. [PMID: 27748433 PMCID: PMC5066272 DOI: 10.1038/srep35628] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 10/04/2016] [Indexed: 12/31/2022] Open
Abstract
Current rescue therapies for life-threatening arrhythmias ignore the pathological electro-anatomical substrate and base their efficacy on a generalized electrical discharge. Here, we developed an all-optical platform to examine less invasive defibrillation strategies. An ultrafast wide-field macroscope was developed to optically map action potential propagation with a red-shifted voltage sensitive dye in whole mouse hearts. The macroscope was implemented with a random-access scanning head capable of drawing arbitrarily-chosen stimulation patterns with sub-millisecond temporal resolution allowing precise epicardial activation of Channelrhodopsin2 (ChR2). We employed this optical system in the setting of ventricular tachycardia to optimize mechanistic, multi-barrier cardioversion/defibrillation patterns. Multiple regions of conduction block were created with a very high cardioversion efficiency but with lower energy requirements as compared to whole ventricle interventions to interrupt arrhythmias. This work demonstrates that defibrillation energies can be substantially reduced by applying discrete stimulation patterns and promotes the progress of current anti-arrhythmic strategies.
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44
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Crocini C, Coppini R, Ferrantini C, Yan P, Loew LM, Poggesi C, Cerbai E, Pavone FS, Sacconi L. T-Tubular Electrical Defects Contribute to Blunted β-Adrenergic Response in Heart Failure. Int J Mol Sci 2016; 17:ijms17091471. [PMID: 27598150 PMCID: PMC5037749 DOI: 10.3390/ijms17091471] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 08/17/2016] [Accepted: 08/30/2016] [Indexed: 11/18/2022] Open
Abstract
Alterations of the β-adrenergic signalling, structural remodelling, and electrical failure of T-tubules are hallmarks of heart failure (HF). Here, we assess the effect of β-adrenoceptor activation on local Ca2+ release in electrically coupled and uncoupled T-tubules in ventricular myocytes from HF rats. We employ an ultrafast random access multi-photon (RAMP) microscope to simultaneously record action potentials and Ca2+ transients from multiple T-tubules in ventricular cardiomyocytes from a HF rat model of coronary ligation compared to sham-operated rats as a control. We confirmed that β-adrenergic stimulation increases the frequency of Ca2+ sparks, reduces Ca2+ transient variability, and hastens the decay of Ca2+ transients: all these effects are similarly exerted by β-adrenergic stimulation in control and HF cardiomyocytes. Conversely, β-adrenergic stimulation in HF cells accelerates a Ca2+ rise exclusively in the proximity of T-tubules that regularly conduct the action potential. The delayed Ca2+ rise found at T-tubules that fail to conduct the action potential is instead not affected by β-adrenergic signalling. Taken together, these findings indicate that HF cells globally respond to β-adrenergic stimulation, except at T-tubules that fail to conduct action potentials, where the blunted effect of the β-adrenergic signalling may be directly caused by the lack of electrical activity.
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Affiliation(s)
- Claudia Crocini
- European Laboratory for Non-Linear Spectroscopy, Florence 50019, Italy.
- National Institute of Optics, National Research Council, Florence 50125, Italy.
| | - Raffaele Coppini
- Division of Pharmacology, Department "NeuroFarBa", University of Florence, Florence 50139, Italy.
| | - Cecilia Ferrantini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence 50134, Italy.
| | - Ping Yan
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT 06030, USA.
| | - Leslie M Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT 06030, USA.
| | - Corrado Poggesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence 50134, Italy.
| | - Elisabetta Cerbai
- Division of Pharmacology, Department "NeuroFarBa", University of Florence, Florence 50139, Italy.
| | - Francesco S Pavone
- European Laboratory for Non-Linear Spectroscopy, Florence 50019, Italy.
- Department of Physics and Astronomy, University of Florence, Sesto Fiorentino 50019, Italy.
| | - Leonardo Sacconi
- European Laboratory for Non-Linear Spectroscopy, Florence 50019, Italy.
- National Institute of Optics, National Research Council, Florence 50125, Italy.
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Bovo E, Martin JL, Tyryfter J, de Tombe PP, Zima AV. R-CEPIA1er as a new tool to directly measure sarcoplasmic reticulum [Ca] in ventricular myocytes. Am J Physiol Heart Circ Physiol 2016; 311:H268-75. [PMID: 27233762 PMCID: PMC4967208 DOI: 10.1152/ajpheart.00175.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/24/2016] [Indexed: 11/22/2022]
Abstract
In cardiomyocytes, [Ca] within the sarcoplasmic reticulum (SR; [Ca]SR) partially determines the amplitude of cytosolic Ca transient that, in turn, governs myocardial contraction. Therefore, it is critical to understand the molecular mechanisms that regulate [Ca]SR handling. Until recently, the best approach available to directly measure [Ca]SR was to use low-affinity Ca indicators (e.g., Fluo-5N). However, this approach presents several limitations, including nonspecific cellular localization, dye extrusion, and species limitation. Recently a new genetically encoded family of Ca indicators has been generated, named Ca-measuring organelle-entrapped protein indicators (CEPIA). Here, we tested the red fluorescence SR-targeted Ca sensor (R-CEPIA1er) as a tool to directly measure [Ca]SR dynamics in ventricular myocytes. Infection of rabbit and rat ventricular myocytes with an adenovirus expressing the R-CEPIA1er gene displayed prominent localization in the SR and nuclear envelope. Calibration of R-CEPIA1er in myocytes resulted in a Kd of 609 μM, suggesting that this sensor is sensitive in the whole physiological range of [Ca]SR [Ca]SR dynamics measured with R-CEPIA1er were compared with [Ca]SR measured with Fluo5-N. We found that both the time course of the [Ca]SR depletion and fractional SR Ca release induced by an action potential were similar between these two Ca sensors. R-CEPIA1er fluorescence did not decline during experiments, indicating lack of dye extrusion or photobleaching. Furthermore, measurement of [Ca]SR with R-CEPIA1er can be combined with cytosolic [Ca] measurements (with Fluo-4) to obtain more detailed information regarding Ca handling in cardiac myocytes. In conclusion, R-CEPIA1er is a promising tool that can be used to measure [Ca]SR dynamics in myocytes from different animal species.
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Affiliation(s)
- Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
| | - Jody L Martin
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
| | - Jollyn Tyryfter
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
| | - Pieter P de Tombe
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
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46
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Uchida K, Moench I, Tamkus G, Lopatin AN. Small membrane permeable molecules protect against osmotically induced sealing of t-tubules in mouse ventricular myocytes. Am J Physiol Heart Circ Physiol 2016; 311:H229-38. [PMID: 27208165 DOI: 10.1152/ajpheart.00836.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 05/16/2016] [Indexed: 02/07/2023]
Abstract
Cardiac t-tubules are critical for efficient excitation-contraction coupling but become significantly remodeled during various stress conditions. However, the mechanisms by which t-tubule remodeling occur are poorly understood. Recently, we demonstrated that recovery of mouse ventricular myocytes after hyposmotic shock is associated with t-tubule sealing. In this study, we found that the application of Small Membrane Permeable Molecules (SMPM) such as DMSO, formamide and acetamide upon washout of hyposmotic solution significantly reduced the amount of extracellular dextran trapped within sealed t-tubules. The SMPM protection displayed sharp biphasic concentration dependence that peaks at ∼140 mM leading to >3- to 4-fold reduction in dextran trapping. Consistent with these data, detailed analysis of the effects of DMSO showed that the magnitude of normalized inward rectifier tail current (IK1,tail), an electrophysiological marker of t-tubular integrity, was increased ∼2-fold when hyposmotic stress was removed in the presence of 1% DMSO (∼140 mM). Analysis of dynamics of cardiomyocytes shrinking during resolution of hyposmotic stress revealed only minor increase in shrinking rate in the presence of 1% DMSO, and cell dimensions returned fully to prestress values in both control and DMSO groups. Application and withdrawal of 10% DMSO in the absence of preceding hyposmotic shock induced classical t-tubule sealing. This suggests that the biphasic concentration dependence originated from an increase in secondary t-tubule sealing when high SMPM concentrations are removed. Overall, the data suggest that SMPM protect against sealing of t-tubules following hyposmotic stress, likely through membrane modification and essentially independent of their osmotic effects.
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Affiliation(s)
- Keita Uchida
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Ian Moench
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Greta Tamkus
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Anatoli N Lopatin
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
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47
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Pioner JM, Racca AW, Klaiman JM, Yang KC, Guan X, Pabon L, Muskheli V, Zaunbrecher R, Macadangdang J, Jeong MY, Mack DL, Childers MK, Kim DH, Tesi C, Poggesi C, Murry CE, Regnier M. Isolation and Mechanical Measurements of Myofibrils from Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Stem Cell Reports 2016; 6:885-896. [PMID: 27161364 PMCID: PMC4911495 DOI: 10.1016/j.stemcr.2016.04.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Revised: 04/06/2016] [Accepted: 04/07/2016] [Indexed: 01/25/2023] Open
Abstract
Tension production and contractile properties are poorly characterized aspects of excitation-contraction coupling of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Previous approaches have been limited due to the small size and structural immaturity of early-stage hiPSC-CMs. We developed a substrate nanopatterning approach to produce hiPSC-CMs in culture with adult-like dimensions, T-tubule-like structures, and aligned myofibrils. We then isolated myofibrils from hiPSC-CMs and measured the tension and kinetics of activation and relaxation using a custom-built apparatus with fast solution switching. The contractile properties and ultrastructure of myofibrils more closely resembled human fetal myofibrils of similar gestational age than adult preparations. We also demonstrated the ability to study the development of contractile dysfunction of myofibrils from a patient-derived hiPSC-CM cell line carrying the familial cardiomyopathy MYH7 mutation (E848G). These methods can bring new insights to understanding cardiomyocyte maturation and developmental mechanical dysfunction of hiPSC-CMs with cardiomyopathic mutations. The contractile properties of hiPSC-CM myofibrils have not been previously studied hiPSC-CMs cultured on nanopatterned surfaces develop elongated, aligned myofibrils hiPSC-CMs myofibrils have contractile properties similar to human fetal myofibrils hiPSC-CMs can be used to study development of genetically based cardiac diseases
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Affiliation(s)
- Josè Manuel Pioner
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Viale Morgagni 63, 50134 Florence, Italy.
| | - Alice W Racca
- Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Jordan M Klaiman
- Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Kai-Chun Yang
- Medicine, Division of Cardiology, University of Washington, Seattle, WA 98195, USA
| | - Xuan Guan
- Rehabilitation Medicine, University of Washington, Seattle, WA 98109, USA
| | - Lil Pabon
- Pathology, University of Washington, Seattle, WA 98109, USA
| | | | | | | | - Mark Y Jeong
- Medicine, Division of Cardiology, University of Colorado, Denver, CO 80262, USA
| | - David L Mack
- Rehabilitation Medicine, University of Washington, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
| | - Martin K Childers
- Rehabilitation Medicine, University of Washington, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
| | - Deok-Ho Kim
- Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Chiara Tesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Viale Morgagni 63, 50134 Florence, Italy
| | - Corrado Poggesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Viale Morgagni 63, 50134 Florence, Italy
| | - Charles E Murry
- Bioengineering, University of Washington, Seattle, WA 98109, USA; Medicine, Division of Cardiology, University of Washington, Seattle, WA 98195, USA; Pathology, University of Washington, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA; Center for Cardiovascular Biology, University of Washington, Seattle, WA 98109, USA
| | - Michael Regnier
- Bioengineering, University of Washington, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA; Center for Cardiovascular Biology, University of Washington, Seattle, WA 98109, USA
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Sildenafil ameliorates left ventricular T-tubule remodeling in a pressure overload-induced murine heart failure model. Acta Pharmacol Sin 2016; 37:473-82. [PMID: 26972492 DOI: 10.1038/aps.2016.13] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 02/06/2016] [Indexed: 12/24/2022] Open
Abstract
AIM Sildenafil, a phosphodiesterase 5 (PDE5) inhibitor, has been shown to exert beneficial effects in heart failure. The purpose of this study was to test whether sildenafil suppressed transverse-tubule (T-tubule) remodeling in left ventricular (LV) failure and thereby providing the therapeutic benefits. METHODS A pressure overload-induced murine heart failure model was established in mice by thoracic aortic banding (TAB). One day after TAB, the mice received sildenafil (100 mg·kg(-1)·d(-1), sc) or saline for 5 weeks. At the end of treatment, echocardiography was used to examine LV function. Then the intact hearts were dissected out and placed in Langendorff-perfusion chamber for in situ confocal imaging of T-tubule ultrastructure from epicardial myocytes. RESULTS TAB surgery resulted in heart failure accompanied by remarkable T-tubule remodeling. Sildenafil treatment significantly attenuated TAB-induced cardiac hypertrophy and congestive heart failure, improved LV contractile function, and preserved T-tubule integrity in LV cardiomyocytes. But sildenafil treatment did not significantly affect the chamber dilation. The integrity of LV T-tubule structure was correlated with cardiac hypertrophy (R(2)=0.74, P<0.01) and global LV function (R(2)=0.47, P<0.01). CONCLUSION Sildenafil effectively ameliorates LV T-tubule remodeling in TAB mice, revealing a novel mechanism underlying the therapeutic benefits of sildenafil in heart failure.
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Morphological Identification of TRPC7 in Cardiomyocytes From Normal and Renovascular Hypertensive Rats [RETRACTED]. J Cardiovasc Pharmacol 2016; 67:121-8. [DOI: 10.1097/fjc.0000000000000321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Crocini C, Ferrantini C, Scardigli M, Coppini R, Mazzoni L, Lazzeri E, Pioner JM, Scellini B, Guo A, Song LS, Yan P, Loew LM, Tardiff J, Tesi C, Vanzi F, Cerbai E, Pavone FS, Sacconi L, Poggesi C. Novel insights on the relationship between T-tubular defects and contractile dysfunction in a mouse model of hypertrophic cardiomyopathy. J Mol Cell Cardiol 2015; 91:42-51. [PMID: 26714042 PMCID: PMC4767219 DOI: 10.1016/j.yjmcc.2015.12.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 11/16/2015] [Accepted: 12/16/2015] [Indexed: 02/06/2023]
Abstract
Abnormalities of cardiomyocyte Ca2 + homeostasis and excitation–contraction (E–C) coupling are early events in the pathogenesis of hypertrophic cardiomyopathy (HCM) and concomitant determinants of the diastolic dysfunction and arrhythmias typical of the disease. T-tubule remodelling has been reported to occur in HCM but little is known about its role in the E–C coupling alterations of HCM. Here, the role of T-tubule remodelling in the electro-mechanical dysfunction associated to HCM is investigated in the Δ160E cTnT mouse model that expresses a clinically-relevant HCM mutation. Contractile function of intact ventricular trabeculae is assessed in Δ160E mice and wild-type siblings. As compared with wild-type, Δ160E trabeculae show prolonged kinetics of force development and relaxation, blunted force-frequency response with reduced active tension at high stimulation frequency, and increased occurrence of spontaneous contractions. Consistently, prolonged Ca2 + transient in terms of rise and duration are also observed in Δ160E trabeculae and isolated cardiomyocytes. Confocal imaging in cells isolated from Δ160E mice reveals significant, though modest, remodelling of T-tubular architecture. A two-photon random access microscope is employed to dissect the spatio-temporal relationship between T-tubular electrical activity and local Ca2 + release in isolated cardiomyocytes. In Δ160E cardiomyocytes, a significant number of T-tubules (> 20%) fails to propagate action potentials, with consequent delay of local Ca2 + release. At variance with wild-type, we also observe significantly increased variability of local Ca2 + transient rise as well as higher Ca2 +-spark frequency. Although T-tubule structural remodelling in Δ160E myocytes is modest, T-tubule functional defects determine non-homogeneous Ca2 + release and delayed myofilament activation that significantly contribute to mechanical dysfunction. Contraction and Ca2 + transient kinetics are impaired in myocardial preparations from mice carrying the cardiac troponin T ∆ 160E mutation. T-tubules architecture is mildly altered in ∆160E cardiomyocytes. 20% of T-tubules fail to propagate action potential and produce delay of local Ca2 + rise. Higher spatio-temporal variability of local Ca2 + rise and increased Ca2 + sparks frequency are found in ∆160E cardiomyocytes.
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Affiliation(s)
- C Crocini
- European Laboratory for Non-Linear Spectroscopy, 50019 Florence, Italy
| | - C Ferrantini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - M Scardigli
- European Laboratory for Non-Linear Spectroscopy, 50019 Florence, Italy
| | - R Coppini
- Division of Pharmacology, Department "NeuroFarBa", University of Florence, 50139 Florence, Italy
| | - L Mazzoni
- Division of Pharmacology, Department "NeuroFarBa", University of Florence, 50139 Florence, Italy
| | - E Lazzeri
- European Laboratory for Non-Linear Spectroscopy, 50019 Florence, Italy
| | - J M Pioner
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - B Scellini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - A Guo
- Division of Cardiovascular Medicine, Department of Internal Medicine and Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - L S Song
- Division of Cardiovascular Medicine, Department of Internal Medicine and Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - P Yan
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - L M Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - J Tardiff
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - C Tesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - F Vanzi
- European Laboratory for Non-Linear Spectroscopy, 50019 Florence, Italy
| | - E Cerbai
- Division of Pharmacology, Department "NeuroFarBa", University of Florence, 50139 Florence, Italy
| | - F S Pavone
- European Laboratory for Non-Linear Spectroscopy, 50019 Florence, Italy; Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino, Italy; National Institute of Optics, National Research Council, 50125 Florence, Italy
| | - L Sacconi
- European Laboratory for Non-Linear Spectroscopy, 50019 Florence, Italy; National Institute of Optics, National Research Council, 50125 Florence, Italy.
| | - C Poggesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy.
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