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Lee C, Xu S, Samad T, Goodyer WR, Raissadati A, Heinrich P, Wu SM. The cardiac conduction system: History, development, and disease. Curr Top Dev Biol 2024; 156:157-200. [PMID: 38556422 DOI: 10.1016/bs.ctdb.2024.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The heart is the first organ to form during embryonic development, establishing the circulatory infrastructure necessary to sustain life and enable downstream organogenesis. Critical to the heart's function is its ability to initiate and propagate electrical impulses that allow for the coordinated contraction and relaxation of its chambers, and thus, the movement of blood and nutrients. Several specialized structures within the heart, collectively known as the cardiac conduction system (CCS), are responsible for this phenomenon. In this review, we discuss the discovery and scientific history of the mammalian cardiac conduction system as well as the key genes and transcription factors implicated in the formation of its major structures. We also describe known human diseases related to CCS development and explore existing challenges in the clinical context.
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Affiliation(s)
- Carissa Lee
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States
| | - Sidra Xu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States
| | - Tahmina Samad
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States; Department of Pediatrics, Stanford University, Stanford, CA, United States
| | - William R Goodyer
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States
| | - Alireza Raissadati
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States
| | - Paul Heinrich
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Cardiology, Klinikum Rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Sean M Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, United States; Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, CA, United States.
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2
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Adams WP, Raisch TB, Zhao Y, Davalos R, Barrett S, King DR, Bain CB, Colucci-Chang K, Blair GA, Hanlon A, Lozano A, Veeraraghavan R, Wan X, Deschenes I, Smyth JW, Hoeker GS, Gourdie RG, Poelzing S. Extracellular Perinexal Separation Is a Principal Determinant of Cardiac Conduction. Circ Res 2023; 133:658-673. [PMID: 37681314 PMCID: PMC10561697 DOI: 10.1161/circresaha.123.322567] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 08/29/2023] [Indexed: 09/09/2023]
Abstract
BACKGROUND Cardiac conduction is understood to occur through gap junctions. Recent evidence supports ephaptic coupling as another mechanism of electrical communication in the heart. Conduction via gap junctions predicts a direct relationship between conduction velocity (CV) and bulk extracellular resistance. By contrast, ephaptic theory is premised on the existence of a biphasic relationship between CV and the volume of specialized extracellular clefts within intercalated discs such as the perinexus. Our objective was to determine the relationship between ventricular CV and structural changes to micro- and nanoscale extracellular spaces. METHODS Conduction and Cx43 (connexin43) protein expression were quantified from optically mapped guinea pig whole-heart preparations perfused with the osmotic agents albumin, mannitol, dextran 70 kDa, or dextran 2 MDa. Peak sodium current was quantified in isolated guinea pig ventricular myocytes. Extracellular resistance was quantified by impedance spectroscopy. Intercellular communication was assessed in a heterologous expression system with fluorescence recovery after photobleaching. Perinexal width was quantified from transmission electron micrographs. RESULTS CV primarily in the transverse direction of propagation was significantly reduced by mannitol and increased by albumin and both dextrans. The combination of albumin and dextran 70 kDa decreased CV relative to albumin alone. Extracellular resistance was reduced by mannitol, unchanged by albumin, and increased by both dextrans. Cx43 expression and conductance and peak sodium currents were not significantly altered by the osmotic agents. In response to osmotic agents, perinexal width, in order of narrowest to widest, was albumin with dextran 70 kDa; albumin or dextran 2 MDa; dextran 70 kDa or no osmotic agent, and mannitol. When compared in the same order, CV was biphasically related to perinexal width. CONCLUSIONS Cardiac conduction does not correlate with extracellular resistance but is biphasically related to perinexal separation, providing evidence that the relationship between CV and extracellular volume is determined by ephaptic mechanisms under conditions of normal gap junctional coupling.
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Affiliation(s)
- William P. Adams
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
| | - Tristan B. Raisch
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
| | - Yajun Zhao
- School of Biomedical Engineering and Sciences, Virginia Tech
| | - Rafael Davalos
- School of Biomedical Engineering and Sciences, Virginia Tech
| | | | - D. Ryan King
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
| | - Chandra B. Bain
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
| | - Katrina Colucci-Chang
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- School of Biomedical Engineering and Sciences, Virginia Tech
| | - Grace A. Blair
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
| | - Alexandra Hanlon
- Virginia Tech Center for Biostatistics and Health Data Science, Roanoke, Virginia
| | - Alicia Lozano
- Virginia Tech Center for Biostatistics and Health Data Science, Roanoke, Virginia
| | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, College of Engineering, The Ohio State University
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center
| | - Xiaoping Wan
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center
| | - Isabelle Deschenes
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center
| | - James W. Smyth
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Department of Biological Sciences, College of Science, Virginia Tech
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, Virginia
| | - Gregory S. Hoeker
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
| | - Robert G. Gourdie
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- School of Biomedical Engineering and Sciences, Virginia Tech
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, Virginia
| | - Steven Poelzing
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
- School of Biomedical Engineering and Sciences, Virginia Tech
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, Virginia
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Pedriali G, Ramaccini D, Bouhamida E, Wieckowski MR, Giorgi C, Tremoli E, Pinton P. Perspectives on mitochondrial relevance in cardiac ischemia/reperfusion injury. Front Cell Dev Biol 2022; 10:1082095. [PMID: 36561366 PMCID: PMC9763599 DOI: 10.3389/fcell.2022.1082095] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
Cardiovascular disease is the most common cause of death worldwide and in particular, ischemic heart disease holds the most considerable position. Even if it has been deeply studied, myocardial ischemia-reperfusion injury (IRI) is still a side-effect of the clinical treatment for several heart diseases: ischemia process itself leads to temporary damage to heart tissue and obviously the recovery of blood flow is promptly required even if it worsens the ischemic injury. There is no doubt that mitochondria play a key role in pathogenesis of IRI: dysfunctions of these important organelles alter cell homeostasis and survival. It has been demonstrated that during IRI the system of mitochondrial quality control undergoes alterations with the disruption of the complex balance between the processes of mitochondrial fusion, fission, biogenesis and mitophagy. The fundamental role of mitochondria is carried out thanks to the finely regulated connection to other organelles such as plasma membrane, endoplasmic reticulum and nucleus, therefore impairments of these inter-organelle communications exacerbate IRI. This review pointed to enhance the importance of the mitochondrial network in the pathogenesis of IRI with the aim to focus on potential mitochondria-targeting therapies as new approach to control heart tissue damage after ischemia and reperfusion process.
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Affiliation(s)
- Gaia Pedriali
- Maria Cecilia Hospital, GVM Care and Research, Cotignola, Italy
| | | | - Esmaa Bouhamida
- Maria Cecilia Hospital, GVM Care and Research, Cotignola, Italy
| | - Mariusz R. Wieckowski
- Laboratory of Mitochondrial Biology and Metabolism, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Carlotta Giorgi
- Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Science, Section of Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Elena Tremoli
- Maria Cecilia Hospital, GVM Care and Research, Cotignola, Italy,*Correspondence: Paolo Pinton, ; Elena Tremoli,
| | - Paolo Pinton
- Maria Cecilia Hospital, GVM Care and Research, Cotignola, Italy,Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Science, Section of Experimental Medicine, University of Ferrara, Ferrara, Italy,*Correspondence: Paolo Pinton, ; Elena Tremoli,
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Peyronnet R, Desai A, Edelmann JC, Cameron BA, Emig R, Kohl P, Dean D. Simultaneous assessment of radial and axial myocyte mechanics by combining atomic force microscopy and carbon fibre techniques. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210326. [PMID: 36189808 PMCID: PMC9527909 DOI: 10.1098/rstb.2021.0326] [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: 03/31/2022] [Accepted: 07/21/2022] [Indexed: 11/12/2022] Open
Abstract
Cardiomyocytes sense and shape their mechanical environment, contributing to its dynamics by their passive and active mechanical properties. While axial forces generated by contracting cardiomyocytes have been amply investigated, the corresponding radial mechanics remain poorly characterized. Our aim is to simultaneously monitor passive and active forces, both axially and radially, in cardiomyocytes freshly isolated from adult mouse ventricles. To do so, we combine a carbon fibre (CF) set-up with a custom-made atomic force microscope (AFM). CF allows us to apply stretch and to record passive and active forces in the axial direction. The AFM, modified for frontal access to fit in CF, is used to characterize radial cell mechanics. We show that stretch increases the radial elastic modulus of cardiomyocytes. We further find that during contraction, cardiomyocytes generate radial forces that are reduced, but not abolished, when cells are forced to contract near isometrically. Radial forces may contribute to ventricular wall thickening during contraction, together with the dynamic re-orientation of cells and sheetlets in the myocardium. This new approach for characterizing cell mechanics allows one to obtain a more detailed picture of the balance of axial and radial mechanics in cardiomyocytes at rest, during stretch, and during contraction. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
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Affiliation(s)
- Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg – Bad Krozingen, University of Freiburg, 79110 Freiburg, Germany
- Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
- National Heart and Lung Institute, Imperial College London, London, UK
| | | | | | - Breanne A. Cameron
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg – Bad Krozingen, University of Freiburg, 79110 Freiburg, Germany
- Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
| | - Ramona Emig
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg – Bad Krozingen, University of Freiburg, 79110 Freiburg, Germany
- Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg – Bad Krozingen, University of Freiburg, 79110 Freiburg, Germany
- Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
- National Heart and Lung Institute, Imperial College London, London, UK
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
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Kohl P, Greiner J, Rog-Zielinska EA. Electron microscopy of cardiac 3D nanodynamics: form, function, future. Nat Rev Cardiol 2022; 19:607-619. [PMID: 35396547 DOI: 10.1038/s41569-022-00677-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/04/2022] [Indexed: 11/09/2022]
Abstract
The 3D nanostructure of the heart, its dynamic deformation during cycles of contraction and relaxation, and the effects of this deformation on cell function remain largely uncharted territory. Over the past decade, the first inroads have been made towards 3D reconstruction of heart cells, with a native resolution of around 1 nm3, and of individual molecules relevant to heart function at a near-atomic scale. These advances have provided access to a new generation of data and have driven the development of increasingly smart, artificial intelligence-based, deep-learning image-analysis algorithms. By high-pressure freezing of cardiomyocytes with millisecond accuracy after initiation of an action potential, pseudodynamic snapshots of contraction-induced deformation of intracellular organelles can now be captured. In combination with functional studies, such as fluorescence imaging, exciting insights into cardiac autoregulatory processes at nano-to-micro scales are starting to emerge. In this Review, we discuss the progress in this fascinating new field to highlight the fundamental scientific insight that has emerged, based on technological breakthroughs in biological sample preparation, 3D imaging and data analysis; to illustrate the potential clinical relevance of understanding 3D cardiac nanodynamics; and to predict further progress that we can reasonably expect to see over the next 10 years.
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Affiliation(s)
- Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Engineering, University of Freiburg, Freiburg, Germany.,Centre for Integrative Biological Signalling Studies (CIBSS), University of Freiburg, Freiburg, Germany
| | - Joachim Greiner
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Eva A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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6
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Inazumi H, Kuwahara K, Nakagawa Y, Kuwabara Y, Numaga-Tomita T, Kashihara T, Nakada T, Kurebayashi N, Oya M, Nonaka M, Sugihara M, Kinoshita H, Moriuchi K, Yanagisawa H, Nishikimi T, Motoki H, Yamada M, Morimoto S, Otsu K, Mortensen RM, Nakao K, Kimura T. NRSF- GNAO1 Pathway Contributes to the Regulation of Cardiac Ca 2+ Homeostasis. Circ Res 2022; 130:234-248. [PMID: 34875852 DOI: 10.1161/circresaha.121.318898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND During the development of heart failure, a fetal cardiac gene program is reactivated and accelerates pathological cardiac remodeling. We previously reported that a transcriptional repressor, NRSF (neuron restrictive silencer factor), suppresses the fetal cardiac gene program, thereby maintaining cardiac integrity. The underlying molecular mechanisms remain to be determined, however. METHODS We aim to elucidate molecular mechanisms by which NRSF maintains normal cardiac function. We generated cardiac-specific NRSF knockout mice and analyzed cardiac gene expression profiles in those mice and mice cardiac-specifically expressing a dominant-negative NRSF mutant. RESULTS We found that cardiac expression of Gαo, an inhibitory G protein encoded in humans by GNAO1, is transcriptionally regulated by NRSF and is increased in the ventricles of several mouse models of heart failure. Genetic knockdown of Gnao1 ameliorated the cardiac dysfunction and prolonged survival rates in these mouse heart failure models. Conversely, cardiac-specific overexpression of GNAO1 in mice was sufficient to induce cardiac dysfunction. Mechanistically, we observed that increasing Gαo expression increased surface sarcolemmal L-type Ca2+ channel activity, activated CaMKII (calcium/calmodulin-dependent kinase-II) signaling, and impaired Ca2+ handling in ventricular myocytes, which led to cardiac dysfunction. CONCLUSIONS These findings shed light on a novel function of Gαo in the regulation of cardiac Ca2+ homeostasis and systolic function and suggest Gαo may be an effective therapeutic target for the treatment of heart failure.
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Affiliation(s)
- Hideaki Inazumi
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
| | - Koichiro Kuwahara
- Cardiovascular Medicine (K.K., M.O., H.M.), School of Medicine, Shinshu University, Matsumoto
| | - Yasuaki Nakagawa
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
| | - Yoshihiro Kuwabara
- Center for Accessing Early Promising Treatment, Kyoto University Hospital (Y.K.)
| | - Takuro Numaga-Tomita
- Molecular Pharmacology (T.N.-T., M.Y.), School of Medicine, Shinshu University, Matsumoto
| | - Toshihide Kashihara
- Molecular Pharmacology, School of Pharmaceutical Sciences, Kitasato University, Tokyo (T. Kashihara)
| | - Tsutomu Nakada
- Research Center for Supports to Advanced Science (T. Nakada), School of Medicine, Shinshu University, Matsumoto
| | - Nagomi Kurebayashi
- Cellular and Molecular Pharmacology, School of Medicine, Juntendo University, Tokyo (N.K.)
| | - Miku Oya
- Cardiovascular Medicine (K.K., M.O., H.M.), School of Medicine, Shinshu University, Matsumoto
| | - Miki Nonaka
- Pain Control Research, The Jikei University School of Medicine (M.N.)
| | - Masami Sugihara
- Clinical Laboratory Medicine, School of Medicine, Juntendo University, Tokyo (M.S.)
| | - Hideyuki Kinoshita
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
| | - Kenji Moriuchi
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
| | | | - Toshio Nishikimi
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
- Wakakusa Tatsuma Rehabilitation Hospital, Osaka (T. Nishikimi)
| | - Hirohiko Motoki
- Cardiovascular Medicine (K.K., M.O., H.M.), School of Medicine, Shinshu University, Matsumoto
| | - Mitsuhiko Yamada
- Molecular Pharmacology (T.N.-T., M.Y.), School of Medicine, Shinshu University, Matsumoto
| | - Sachio Morimoto
- School of Health Sciences Fukuoka, International University of Health and Welfare, Okawa (S.M.)
| | - Kinya Otsu
- The School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, United Kingdom (K.O.)
| | | | - Kazuwa Nakao
- Medical Innovation Center (K.N.), Graduate School of Medicine, Kyoto University
| | - Takeshi Kimura
- Cardiovascular Medicine (H.I., Y.N., H.K., K.M., H.Y., T. Nishikimi, T. Kimura), Graduate School of Medicine, Kyoto University
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Greiner J, Schiatti T, Kaltenbacher W, Dente M, Semenjakin A, Kok T, Fiegle DJ, Seidel T, Ravens U, Kohl P, Peyronnet R, Rog-Zielinska EA. Consecutive-Day Ventricular and Atrial Cardiomyocyte Isolations from the Same Heart: Shifting the Cost-Benefit Balance of Cardiac Primary Cell Research. Cells 2022; 11:233. [PMID: 35053351 PMCID: PMC8773758 DOI: 10.3390/cells11020233] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 01/03/2022] [Accepted: 01/05/2022] [Indexed: 02/04/2023] Open
Abstract
Freshly isolated primary cardiomyocytes (CM) are indispensable for cardiac research. Experimental CM research is generally incompatible with life of the donor animal, while human heart samples are usually small and scarce. CM isolation from animal hearts, traditionally performed by coronary artery perfusion of enzymes, liberates millions of cells from the heart. However, due to progressive cell remodeling following isolation, freshly isolated primary CM need to be used within 4-8 h post-isolation for most functional assays, meaning that the majority of cells is essentially wasted. In addition, coronary perfusion-based isolation cannot easily be applied to human tissue biopsies, and it does not straightforwardly allow for assessment of regional differences in CM function within the same heart. Here, we provide a method of multi-day CM isolation from one animal heart, yielding calcium-tolerant ventricular and atrial CM. This is based on cell isolation from cardiac tissue slices following repeated (usually overnight) storage of the tissue under conditions that prolong CM viability beyond the day of organ excision by two additional days. The maintenance of cells in their near-native microenvironment slows the otherwise rapid structural and functional decline seen in isolated CM during attempts for prolonged storage or culture. Multi-day slice-based CM isolation increases the amount of useful information gained per animal heart, improving reproducibility and reducing the number of experimental animals required in basic cardiac research. It also opens the doors to novel experimental designs, including exploring same-heart regional differences.
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Affiliation(s)
- Joachim Greiner
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen and Faculty of Medicine, Albert-Ludwig University of Freiburg, 79110 Freiburg im Breisgau, Germany
| | - Teresa Schiatti
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen and Faculty of Medicine, Albert-Ludwig University of Freiburg, 79110 Freiburg im Breisgau, Germany
| | - Wenzel Kaltenbacher
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen and Faculty of Medicine, Albert-Ludwig University of Freiburg, 79110 Freiburg im Breisgau, Germany
| | - Marica Dente
- Department of Experimental and Clinical Medicine, Division of Physiology, University of Florence, 50134 Florence, Italy
| | - Alina Semenjakin
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen and Faculty of Medicine, Albert-Ludwig University of Freiburg, 79110 Freiburg im Breisgau, Germany
| | - Thomas Kok
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen and Faculty of Medicine, Albert-Ludwig University of Freiburg, 79110 Freiburg im Breisgau, Germany
| | - Dominik J Fiegle
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-University of Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Thomas Seidel
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-University of Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Ursula Ravens
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen and Faculty of Medicine, Albert-Ludwig University of Freiburg, 79110 Freiburg im Breisgau, Germany
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen and Faculty of Medicine, Albert-Ludwig University of Freiburg, 79110 Freiburg im Breisgau, Germany
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79110 Freiburg im Breisgau, Germany
| | - Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen and Faculty of Medicine, Albert-Ludwig University of Freiburg, 79110 Freiburg im Breisgau, Germany
| | - Eva A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen and Faculty of Medicine, Albert-Ludwig University of Freiburg, 79110 Freiburg im Breisgau, Germany
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8
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Ali R, El-Boubbou K, Boudjelal M. An easy, fast and inexpensive method of preparing a biological specimen for scanning electron microscopy (SEM). MethodsX 2021; 8:101521. [PMID: 34754792 PMCID: PMC8564727 DOI: 10.1016/j.mex.2021.101521] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 09/17/2021] [Indexed: 11/17/2022] Open
Abstract
Biological samples usually require cumbersome preparation steps before SEM imaging. Here we propose a simple, fast and inexpensive method to prepare and visualize biological cell culture samples in a few easy steps. We have tested this method with success on several adherent breast cancer and non-adherent leukemia cell lines. This method gives results comparable to other well-established techniques, and it can be convenient in day-to-day biological sample preparation for SEM imaging.•An easy and rapid method to visualize biological specimens under SEM.•Cells are grown on carbon tapes and gold coated.•Air drying without compromising the image quality.
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Affiliation(s)
- Rizwan Ali
- Medical Research Core Facility and Platforms (MRCFP), King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), Ministry of National Guard Health Affairs (MNGHA), Riyadh 11481, Kingdom of Saudi Arabia
| | - Kheireddine El-Boubbou
- Medical Research Core Facility and Platforms (MRCFP), King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), Ministry of National Guard Health Affairs (MNGHA), Riyadh 11481, Kingdom of Saudi Arabia
- Department of Basic Sciences, College of Science & Health Professions (COSHP), King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), King Abdulaziz Medical City, National Guard Health Affairs, Riyadh 11481, Saudi Arabia
| | - Mohamed Boudjelal
- Medical Research Core Facility and Platforms (MRCFP), King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), Ministry of National Guard Health Affairs (MNGHA), Riyadh 11481, Kingdom of Saudi Arabia
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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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10
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Montes de Oca Balderas P. Mitochondria-plasma membrane interactions and communication. J Biol Chem 2021; 297:101164. [PMID: 34481840 PMCID: PMC8503596 DOI: 10.1016/j.jbc.2021.101164] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 08/24/2021] [Accepted: 09/01/2021] [Indexed: 11/28/2022] Open
Abstract
Mitochondria are known as the powerhouses of eukaryotic cells; however, they perform many other functions besides oxidative phosphorylation, including Ca2+ homeostasis, lipid metabolism, antiviral response, and apoptosis. Although other hypotheses exist, mitochondria are generally thought as descendants of an α-proteobacteria that adapted to the intracellular environment within an Asgard archaebacteria, which have been studied for decades as an organelle subdued by the eukaryotic cell. Nevertheless, several early electron microscopy observations hinted that some mitochondria establish specific interactions with certain plasma membrane (PM) domains in mammalian cells. Furthermore, recent findings have documented the direct physical and functional interaction of mitochondria and the PM, the organization of distinct complexes, and their communication through vesicular means. In yeast, some molecular players mediating this interaction have been elucidated, but only a few works have studied this interaction in mammalian cells. In addition, mitochondria can be translocated among cells through tunneling nanotubes or by other mechanisms, and free, intact, functional mitochondria have been reported in the blood plasma. Together, these findings challenge the conception of mitochondria as organelles subdued by the eukaryotic cell. This review discusses the evidence of the mitochondria interaction with the PM that has been long disregarded despite its importance in cell function, pathogenesis, and evolution. It also proposes a scheme of mitochondria–PM interactions with the intent to promote research and knowledge of this emerging pathway that promises to shift the current paradigms of cell biology.
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Affiliation(s)
- Pavel Montes de Oca Balderas
- Unidad de Neurobiología Dinámica, Department of Neurochemistry, Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico; Lab. BL-305, Instituto de Fisiología Celular, Department of Cognitive Neuroscience, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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11
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Rog-Zielinska EA, Moss R, Kaltenbacher W, Greiner J, Verkade P, Seemann G, Kohl P, Cannell MB. Nano-scale morphology of cardiomyocyte t-tubule/sarcoplasmic reticulum junctions revealed by ultra-rapid high-pressure freezing and electron tomography. J Mol Cell Cardiol 2021; 153:86-92. [PMID: 33359037 PMCID: PMC8035077 DOI: 10.1016/j.yjmcc.2020.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 11/27/2020] [Accepted: 12/16/2020] [Indexed: 11/13/2022]
Abstract
Detailed knowledge of the ultrastructure of intracellular compartments is a prerequisite for our understanding of how cells function. In cardiac muscle cells, close apposition of transverse (t)-tubule (TT) and sarcoplasmic reticulum (SR) membranes supports stable high-gain excitation-contraction coupling. Here, the fine structure of this key intracellular element is examined in rabbit and mouse ventricular cardiomyocytes, using ultra-rapid high-pressure freezing (HPF, omitting aldehyde fixation) and electron microscopy. 3D electron tomograms were used to quantify the dimensions of TT, terminal cisternae of the SR, and the space between SR and TT membranes (dyadic cleft). In comparison to conventional aldehyde-based chemical sample fixation, HPF-preserved samples of both species show considerably more voluminous SR terminal cisternae, both in absolute dimensions and in terms of junctional SR to TT volume ratio. In rabbit cardiomyocytes, the average dyadic cleft surface area of HPF and chemically fixed myocytes did not differ, but cleft volume was significantly smaller in HPF samples than in conventionally fixed tissue; in murine cardiomyocytes, the dyadic cleft surface area was higher in HPF samples with no difference in cleft volume. In both species, the apposition of the TT and SR membranes in the dyad was more likely to be closer than 10 nm in HPF samples compared to CFD, presumably resulting from avoidance of sample shrinkage associated with conventional fixation techniques. Overall, we provide a note of caution regarding quantitative interpretation of chemically-fixed ultrastructures, and offer novel insight into cardiac TT and SR ultrastructure with relevance for our understanding of cardiac physiology.
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Affiliation(s)
- E A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg·Bad Krozingen, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - R Moss
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg·Bad Krozingen, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - W Kaltenbacher
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg·Bad Krozingen, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - J Greiner
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg·Bad Krozingen, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - P Verkade
- School of Biochemistry, Faculty of Biomedical Sciences, University of Bristol, Bristol, UK
| | - G Seemann
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg·Bad Krozingen, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - P Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg·Bad Krozingen, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - M B Cannell
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK.
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12
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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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13
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Fernández MC, Kopton RA, Simon-Chica A, Madl J, Hilgendorf I, Zgierski-Johnston CM, Schneider-Warme F. Channelrhodopsins for Cell-Type Specific Illumination of Cardiac Electrophysiology. Methods Mol Biol 2021; 2191:287-307. [PMID: 32865751 DOI: 10.1007/978-1-0716-0830-2_17] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Optogenetic approaches have evolved as potent means to investigate cardiac electrophysiology, with research ranging from the study of arrhythmia mechanisms to effects of cardiac innervation and heterocellular structural and functional interactions, both in healthy and diseased myocardium. Most commonly, these studies use channelrhodopsin-2 (ChR2)-expressing murine models that enable light-activated depolarization of the target cell population. However, each newly generated mouse line requires thorough characterization, as cell-type specific ChR2 expression cannot be taken for granted, and the electrophysiological response of its activation in the target cell should be evaluated. In this chapter, we describe detailed protocols for assessing ChR2 specificity using immunohistochemistry, isolation of specific cell populations to analyze electrophysiological effects of ChR2 activation with the patch-clamp technique, and whole-heart experiments to assess in situ effects of optical stimulation.
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Affiliation(s)
- Marbely C Fernández
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Ramona A Kopton
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Ana Simon-Chica
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Josef Madl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ingo Hilgendorf
- Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Department of Cardiology I, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany
| | - Callum M Zgierski-Johnston
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Franziska Schneider-Warme
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany. .,Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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14
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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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15
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Lu F, Pu WT. The architecture and function of cardiac dyads. Biophys Rev 2020; 12:1007-1017. [PMID: 32661902 PMCID: PMC7429583 DOI: 10.1007/s12551-020-00729-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 07/03/2020] [Indexed: 12/28/2022] Open
Abstract
Cardiac excitation-contraction (EC) coupling, which links plasma membrane depolarization to activation of cardiomyocyte contraction, occurs at dyads, the nanoscopic microdomains formed by apposition of transverse (T)-tubules and junctional sarcoplasmic reticulum (jSR). In a dyadic junction, EC coupling occurs through Ca2+-induced Ca2+ release. Membrane depolarization opens voltage-gated L-type Ca2+ channels (LTCCs) in the T-tubule. The resulting influx of extracellular Ca2+ into the dyadic cleft opens Ca2+ release channels known as ryanodine receptors (RYRs) in the jSR, leading to the rapid increase in cytosolic Ca2+ that triggers sarcomere contraction. The efficacy of LTCC-RYR communication greatly affects a myriad of downstream intracellular signaling events, and it is controlled by many factors, including T-tubule and jSR structure, spatial distribution of ion channels, and regulatory proteins that closely regulate the activities of channels within dyads. Alterations in dyad architecture and/or channel activity are seen in many types of heart disease. This review will focus on the current knowledge regarding cardiac dyad structure and function, their alterations in heart failure, and new approaches to study the composition and function of dyads.
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Affiliation(s)
- Fujian Lu
- Department of Cardiology, Boston Children's Hospital, 300 Longwood Ave, Boston, MA, 02115, USA
| | - William T Pu
- Department of Cardiology, Boston Children's Hospital, 300 Longwood Ave, Boston, MA, 02115, USA.
- Harvard Stem Cell Institute, 7 Divinity Avenue, Cambridge, MA, 02138, USA.
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16
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MacDonald EA, Madl J, Greiner J, Ramadan AF, Wells SM, Torrente AG, Kohl P, Rog-Zielinska EA, Quinn TA. Sinoatrial Node Structure, Mechanics, Electrophysiology and the Chronotropic Response to Stretch in Rabbit and Mouse. Front Physiol 2020; 11:809. [PMID: 32774307 PMCID: PMC7388775 DOI: 10.3389/fphys.2020.00809] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 06/18/2020] [Indexed: 12/12/2022] Open
Abstract
The rhythmic electrical activity of the heart's natural pacemaker, the sinoatrial node (SAN), determines cardiac beating rate (BR). SAN electrical activity is tightly controlled by multiple factors, including tissue stretch, which may contribute to adaptation of BR to changes in venous return. In most animals, including human, there is a robust increase in BR when the SAN is stretched. However, the chronotropic response to sustained stretch differs in mouse SAN, where it causes variable responses, including decreased BR. The reasons for this species difference are unclear. They are thought to relate to dissimilarities in SAN electrophysiology (particularly action potential morphology) between mouse and other species and to how these interact with subcellular stretch-activated mechanisms. Furthermore, species-related differences in structural and mechanical properties of the SAN may influence the chronotropic response to SAN stretch. Here we assess (i) how the BR response to sustained stretch of rabbit and mouse isolated SAN relates to tissue stiffness, (ii) whether structural differences could account for observed differences in BR responsiveness to stretch, and (iii) whether pharmacological modification of mouse SAN electrophysiology alters stretch-induced chronotropy. We found disparities in the relationship between SAN stiffness and the magnitude of the chronotropic response to stretch between rabbit and mouse along with differences in SAN collagen structure, alignment, and changes with stretch. We further observed that pharmacological modification to prolong mouse SAN action potential plateau duration rectified the direction of BR changes during sustained stretch, resulting in a positive chronotropic response akin to that of other species. Overall, our results suggest that structural, mechanical, and background electrophysiological properties of the SAN influence the chronotropic response to stretch. Improved insight into the biophysical determinants of stretch effects on SAN pacemaking is essential for a comprehensive understanding of SAN regulation with important implications for studies of SAN physiology and its dysfunction, such as in the aging and fibrotic heart.
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Affiliation(s)
- Eilidh A MacDonald
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Josef Madl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Joachim Greiner
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ahmed F Ramadan
- Department of Electrical and Computer Engineering, Dalhousie University, Halifax, NS, Canada
| | - Sarah M Wells
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
| | - Angelo G Torrente
- Department of Physiology, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Eva A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada.,Department of Electrical and Computer Engineering, Dalhousie University, Halifax, NS, Canada
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17
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Darkow E, Rog-Zielinska EA, Madl J, Brandel A, Siukstaite L, Omidvar R, Kohl P, Ravens U, Römer W, Peyronnet R. The Lectin LecA Sensitizes the Human Stretch-Activated Channel TREK-1 but Not Piezo1 and Binds Selectively to Cardiac Non-myocytes. Front Physiol 2020; 11:457. [PMID: 32499717 PMCID: PMC7243936 DOI: 10.3389/fphys.2020.00457] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 04/15/2020] [Indexed: 12/16/2022] Open
Abstract
The healthy heart adapts continuously to a complex set of dynamically changing mechanical conditions. The mechanical environment is altered by, and contributes to, multiple cardiac diseases. Mechanical stimuli are detected and transduced by cellular mechano-sensors, including stretch-activated ion channels (SAC). The precise role of SAC in the heart is unclear, in part because there are few SAC-specific pharmacological modulators. That said, most SAC can be activated by inducers of membrane curvature. The lectin LecA is a virulence factor of Pseudomonas aeruginosa and essential for P. aeruginosa-induced membrane curvature, resulting in formation of endocytic structures and bacterial cell invasion. We investigate whether LecA modulates SAC activity. TREK-1 and Piezo1 have been selected, as they are widely expressed in the body, including cardiac tissue, and they are “canonical representatives” for the potassium selective and the cation non-selective SAC families, respectively. Live cell confocal microscopy and electron tomographic imaging were used to follow binding dynamics of LecA, and to track changes in cell morphology and membrane topology in human embryonic kidney (HEK) cells and in giant unilamellar vesicles (GUV). HEK cells were further transfected with human TREK-1 or Piezo1 constructs, and ion channel activity was recorded using the patch-clamp technique. Finally, freshly isolated cardiac cells were used for studies into cell type dependency of LecA binding. LecA (500 nM) binds within seconds to the surface of HEK cells, with highest concentration at cell-cell contact sites. Local membrane invaginations are detected in the presence of LecA, both in the plasma membrane of cells (by 17 min of LecA exposure) as well as in GUV. In HEK cells, LecA sensitizes TREK-1, but not Piezo1, to voltage and mechanical stimulation. In freshly isolated cardiac cells, LecA binds to non-myocytes, but not to ventricular or atrial cardiomyocytes. This cell type specific lack of binding is observed across cardiomyocytes from mouse, rabbit, pig, and human. Our results suggest that LecA may serve as a pharmacological tool to study SAC in a cell type-preferential manner. This could aid tissue-based research into the roles of SAC in cardiac non-myocytes.
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Affiliation(s)
- Elisa Darkow
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Eva A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Josef Madl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Annette Brandel
- Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Lina Siukstaite
- Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Ramin Omidvar
- Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Ursula Ravens
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Winfried Römer
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Center-University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
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18
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The caveolar-mitochondrial interface: regulation of cellular metabolism in physiology and pathophysiology. Biochem Soc Trans 2020; 48:165-177. [PMID: 32010944 DOI: 10.1042/bst20190388] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 12/15/2022]
Abstract
The plasma membrane is an important cellular organelle that is often overlooked in terms of a primary factor in regulating physiology and pathophysiology. There is emerging evidence to suggest that the plasma membrane serves a greater purpose than a simple barrier or transporter of ions. New paradigms suggest that the membrane serves as a critical bridge to connect extracellular to intracellular communication particularly to regulate energy and metabolism by forming physical and biochemical associations with intracellular organelles. This review will focus on the relationship of a particular membrane microdomain - caveolae - with mitochondria and the particular implication of this to physiology and pathophysiology.
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19
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Rog-Zielinska EA, Kong CHT, Zgierski-Johnston CM, Verkade P, Mantell J, Cannell MB, Kohl P. Species differences in the morphology of transverse tubule openings in cardiomyocytes. Europace 2019; 20:iii120-iii124. [PMID: 30476062 PMCID: PMC6251183 DOI: 10.1093/europace/euy245] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 10/04/2018] [Indexed: 12/11/2022] Open
Abstract
Aims The ultrastructure of ventricular cardiomyocyte T-tubule connections with the outer cell surface ('mouth' regions) has been reported to differ between mice and rabbits. In mice, T-tubule mouths form convoluted narrow spaces filled with electron-dense matter that impedes diffusion between T-tubular lumen and bulk extracellular space. Here, we explore whether T-tubule mouths are also constricted in rat (another murine model used frequently for cardiac research) and whether pig and human T-tubule mouth configurations are structurally more similar to mice or rabbits. Methods and results We used chemically-fixed tissue and high-pressure frozen isolated cardiomyocytes to compare T-tubule mouth architecture using transmission electron microscopy and three-dimensional electron tomography. We find that rat T-tubular mouth architecture is more similar to that of rabbits than mice, lacking the marked tortuosity and electron-dense ground substance that obstructs access to deeper portions of the T-tubular system in mice. Pilot observations in larger mammals (pig, human) suggest that mouse may be the least representative animal model of T-tubule connectivity with the outer cell surface in larger mammals. Conclusion Rat T-tubular system architecture appears to be more similar in size and topology to larger mammals than mice. T-tubular mouth topology may contribute to differences in experimental model behaviour, underscoring the challenge of appropriate model selection for research into cell and tissue function.
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Affiliation(s)
- Eva Alicja Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Faculty of Medicine, University of Freiburg, Elsässerstraße 2Q, Freiburg, Germany
| | - Cherrie Hei Ting Kong
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, Bristol, UK
| | - Callum Michael Zgierski-Johnston
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Faculty of Medicine, University of Freiburg, Elsässerstraße 2Q, Freiburg, Germany
| | - Paul Verkade
- School of Biochemistry and Wolfson Bioimaging Facility, Faculty of Biomedical Sciences, University of Bristol, Bristol, UK
| | - Judith Mantell
- School of Biochemistry and Wolfson Bioimaging Facility, Faculty of Biomedical Sciences, University of Bristol, Bristol, UK
| | - Mark Bryden Cannell
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, Bristol, UK
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Faculty of Medicine, University of Freiburg, Elsässerstraße 2Q, Freiburg, Germany
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20
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Segal S, Kirschner Peretz N, Arbel-Ganon L, Liang J, Li L, Marbach D, Yang D, Wang SQ, Yaniv Y. Eliminating contraction during culture maintains global and local Ca 2+ dynamics in cultured rabbit pacemaker cells. Cell Calcium 2018; 78:35-47. [PMID: 30594820 DOI: 10.1016/j.ceca.2018.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 12/17/2018] [Accepted: 12/17/2018] [Indexed: 12/12/2022]
Abstract
Pacemaker cells residing in the sinoatrial node generate the regular heartbeat. Ca2+ signaling controls the heartbeat rate-directly, through the effect on membrane molecules (NCX exchange, K+ channel), and indirectly, through activation of calmodulin-AC-cAMP-PKA signaling. Thus, the physiological role of signaling in pacemaker cells can only be assessed if the Ca2+ dynamics are in the physiological range. Cultured cells that can be genetically manipulated and/or virally infected with probes are required for this purpose. Because rabbit pacemaker cells in culture experience a decrease in their spontaneous action potential (AP) firing rate below the physiological range, Ca2+ dynamics are expected to be affected. However, Ca2+ dynamics in cultured pacemaker cells have not been reported before. We aim to a develop a modified culture method that sustains the global and local Ca2+ kinetics along with the AP firing rate of rabbit pacemaker cells. We used experimental and computational tools to test the viability of rabbit pacemaker cells in culture under various conditions. We tested the effect of culture dish coating, pH, phosphorylation, and energy balance on cultured rabbit pacemaker cells function. The cells were maintained in culture for 48 h in two types of culture media: one without the addition of a contraction uncoupler and one enriched with either 10 mM BDM (2,3-Butanedione 2-monoxime) or 25 μM blebbistatin. The uncoupler was washed out from the medium prior to the experiments. Cells were successfully infected with a GFP adenovirus cultured with either BDM or blebbistatin. Using either uncoupler during culture led to the cell surface area being maintained at the same level as fresh cells. Moreover, the phospholamban and ryanodine receptor densities and their phosphorylation level remained intact in culture when either blebbistatin or BDM were present. Spontaneous AP firing rate, spontaneous Ca2+ kinetics, and spontaneous local Ca2+ release parameters were similar in the cultured cells with blebbistatin as in fresh cells. However, BDM affects these parameters. Using experimental and a computational model, we showed that by eliminating contraction, phosphorylation activity is preserved and energy is reduced. However, the side-effects of BDM render it less effective than blebbistatin.
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Affiliation(s)
- Sofia Segal
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
| | | | | | - Jinghui Liang
- College of Life Sciences, Peking University, Beijing, China
| | - Linlin Li
- College of Life Sciences, Peking University, Beijing, China
| | - Daphna Marbach
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, USA
| | - Shi-Qiang Wang
- College of Life Sciences, Peking University, Beijing, China
| | - Yael Yaniv
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel.
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21
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Nikouee A, Uchida K, Moench I, Lopatin AN. Cholesterol Protects Against Acute Stress-Induced T-Tubule Remodeling in Mouse Ventricular Myocytes. Front Physiol 2018; 9:1516. [PMID: 30483142 PMCID: PMC6240595 DOI: 10.3389/fphys.2018.01516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 10/09/2018] [Indexed: 12/28/2022] Open
Abstract
Efficient excitation-contraction coupling in ventricular myocytes depends critically on the presence of the t-tubular network. It has been recently demonstrated that cholesterol, a major component of the lipid bilayer, plays an important role in long-term maintenance of the integrity of t-tubular system although mechanistic understanding of underlying processes is essentially lacking. Accordingly, in this study we investigated the contribution of membrane cholesterol to t-tubule remodeling in response to acute hyposmotic stress. Experiments were performed using isolated left ventricular cardiomyocytes from adult mice. Depletion and restoration of membrane cholesterol was achieved by applying methyl-β-cyclodextrin (MβCD) and water soluble cholesterol (WSC), respectively, and t-tubule remodeling in response to acute hyposmotic stress was assessed using fluorescent dextran trapping assay and by measuring t-tubule dependent IK1 tail current (IK1,tail). The amount of dextran trapped in t-tubules sealed in response to stress was significantly increased when compared to control cells, and reintroduction of cholesterol to cells treated with MβCD restored the amount of trapped dextran to control values. Alternatively, application of WSC to normal cells significantly reduced the amount of trapped dextran further suggesting the protective effect of cholesterol. Importantly, modulation of membrane cholesterol (without osmotic stress) led to significant changes in various parameters of IK1, tail strongly suggesting significant but essentially hidden remodeling of t-tubules prior to osmotic stress. Results of this study demonstrate that modulation of the level of membrane cholesterol has significant effects on the susceptibility of cardiac t-tubules to acute hyposmotic stress.
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Affiliation(s)
- Azadeh Nikouee
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Keita Uchida
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Ian Moench
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Anatoli N Lopatin
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
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22
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Rog-Zielinska EA, O'Toole ET, Hoenger A, Kohl P. Mitochondrial Deformation During the Cardiac Mechanical Cycle. Anat Rec (Hoboken) 2018; 302:146-152. [PMID: 30302911 PMCID: PMC6312496 DOI: 10.1002/ar.23917] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 04/22/2018] [Accepted: 05/11/2018] [Indexed: 12/17/2022]
Abstract
Cardiomyocytes both cause and experience continual cyclic deformation. The exact effects of this deformation on the properties of intracellular organelles are not well characterized, although they are likely to be relevant for cardiomyocyte responses to active and passive changes in their mechanical environment. In the present study we provide three‐dimensional ultrastructural evidence for mechanically induced mitochondrial deformation in rabbit ventricular cardiomyocytes over a range of sarcomere lengths representing myocardial tissue stretch, an unloaded “slack” state, and contracture. We also show structural indications for interaction of mitochondria with one another, as well as with other intracellular elements such as microtubules, sarcoplasmic reticulum and T‐tubules. The data presented here help to contextualize recent reports on the mechanosensitivity and cell‐wide connectivity of the mitochondrial network and provide a structural framework that may aide interpretation of mechanically‐regulated molecular signaling in cardiac cells. Anat Rec, 302:146–152, 2019. © 2018 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- E A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg, Bad Krozingen, and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - E T O'Toole
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado, USA
| | - A Hoenger
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado, USA
| | - P Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg, Bad Krozingen, and Faculty of Medicine, University of Freiburg, Freiburg, Germany
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23
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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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24
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Bhogal NK, Hasan A, Gorelik J. The Development of Compartmentation of cAMP Signaling in Cardiomyocytes: The Role of T-Tubules and Caveolae Microdomains. J Cardiovasc Dev Dis 2018; 5:jcdd5020025. [PMID: 29751502 PMCID: PMC6023514 DOI: 10.3390/jcdd5020025] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/18/2018] [Accepted: 04/28/2018] [Indexed: 12/26/2022] Open
Abstract
3′-5′-cyclic adenosine monophosphate (cAMP) is a signaling messenger produced in response to the stimulation of cellular receptors, and has a myriad of functional applications depending on the cell type. In the heart, cAMP is responsible for regulating the contraction rate and force; however, cAMP is also involved in multiple other functions. Compartmentation of cAMP production may explain the specificity of signaling following a stimulus. In particular, transverse tubules (T-tubules) and caveolae have been found to be critical structural components for the spatial confinement of cAMP in cardiomyocytes, as exemplified by beta-adrenergic receptor (β-ARs) signaling. Pathological alterations in cardiomyocyte microdomain architecture led to a disruption in compartmentation of the cAMP signal. In this review, we discuss the difference between atrial and ventricular cardiomyocytes in respect to microdomain organization, and the pathological changes of atrial and ventricular cAMP signaling in response to myocyte dedifferentiation. In addition, we review the role of localized phosphodiesterase (PDE) activity in constraining the cAMP signal. Finally, we discuss microdomain biogenesis and maturation of cAMP signaling with the help of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Understanding these mechanisms may help to overcome the detrimental effects of pathological structural remodeling.
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Affiliation(s)
- Navneet K Bhogal
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, London W12 0NN, UK.
| | - Alveera Hasan
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, London W12 0NN, UK.
| | - Julia Gorelik
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, London W12 0NN, UK.
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25
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Norman R, Fuller W, Calaghan S. Caveolae and the cardiac myocyte. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2017.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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26
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Johnston CM, Krafft AJ, Russe MF, Rog-Zielinska EA. A new look at the heart-novel imaging techniques. Herzschrittmacherther Elektrophysiol 2017; 29:14-23. [PMID: 29242981 DOI: 10.1007/s00399-017-0546-7] [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] [Received: 10/06/2017] [Accepted: 11/24/2017] [Indexed: 01/20/2023]
Abstract
The development and successful implementation of cutting-edge imaging technologies to visualise cardiac anatomy and function is a key component of effective diagnostic efforts in cardiology. Here, we describe a number of recent exciting advances in the field of cardiology spanning from macro- to micro- to nano-scales of observation, including magnetic resonance imaging, computed tomography, optical mapping, photoacoustic imaging, and electron tomography. The methodologies discussed are currently making the transition from scientific research to routine clinical use, albeit at different paces. We discuss the most likely trajectory of this transition into clinical research and standard diagnostics, and highlight the key challenges and opportunities associated with each of the methodologies.
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Affiliation(s)
- C M Johnston
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center - University of Freiburg, and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - A J Krafft
- Department of Radiology, Medical Physics, Medical Center - Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - M F Russe
- Department of Radiology, Medical Center - Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - E A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center - University of Freiburg, and Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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