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Lang D, Medvedev RY, Ratajczyk L, Zheng J, Yuan X, Lim E, Han OY, Valdivia HH, Glukhov AV. Region-specific distribution of transversal-axial tubule system organization underlies heterogeneity of calcium dynamics in the right atrium. Am J Physiol Heart Circ Physiol 2022; 322:H269-H284. [PMID: 34951544 PMCID: PMC8782648 DOI: 10.1152/ajpheart.00381.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The atrial myocardium demonstrates the highly heterogeneous organization of the transversal-axial tubule system (TATS), although its anatomical distribution and region-specific impact on Ca2+ dynamics remain unknown. Here, we developed a novel method for high-resolution confocal imaging of TATS in intact live mouse atrial myocardium and applied a custom-developed MATLAB-based computational algorithm for the automated analysis of TATS integrity. We observed a twofold higher (P < 0.01) TATS density in the right atrial appendage (RAA) than in the intercaval regions (ICR, the anatomical region between the superior vena cava and atrioventricular junction and between the crista terminalis and interatrial septum). Whereas RAA predominantly consisted of well-tubulated myocytes, ICR showed partially tubulated/untubulated cells. Similar TATS distribution was also observed in healthy human atrial myocardium sections. In both mouse atrial preparations and isolated mouse atrial myocytes, we observed a strong anatomical correlation between TATS distribution and Ca2+ transient synchronization and rise-up time. This region-specific difference in Ca2+ transient morphology disappeared after formamide-induced detubulation. ICR myocytes showed a prolonged action potential duration at 80% of repolarization as well as a significantly lower expression of RyR2 and Cav1.2 proteins but similar levels of NCX1 and Cav1.3 compared with RAA tissue. Our findings provide a detailed characterization of the region-specific distribution of TATS in mouse and human atrial myocardium, highlighting the structural foundation for anatomical heterogeneity of Ca2+ dynamics and contractility in the atria. These results could indicate different roles of TATS in Ca2+ signaling at distinct anatomical regions of the atria and provide mechanistic insight into pathological atrial remodeling.NEW & NOTEWORTHY Mouse and human atrial myocardium demonstrate high variability in the organization of the transversal-axial tubule system (TATS), with more organized TATS expressed in the right atrial appendage. TATS distribution governs anatomical heterogeneity of Ca2+ dynamics and thus could contribute to integral atrial contractility, mechanics, and arrhythmogenicity.
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Affiliation(s)
- Di Lang
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Roman Y Medvedev
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Lucas Ratajczyk
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Jingjing Zheng
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Xiaoyu Yuan
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Evi Lim
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Owen Y Han
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Hector H Valdivia
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Alexey V Glukhov
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
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2
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Abstract
Scanning ion conductance microscopy (SICM) has emerged as a versatile tool for studies of interfaces in biology and materials science with notable utility in biophysical and electrochemical measurements. The heart of the SICM is a nanometer-scale electrolyte filled glass pipette that serves as a scanning probe. In the initial conception, manipulations of ion currents through the tip of the pipette and appropriate positioning hardware provided a route to recording micro- and nanoscopic mapping of the topography of surfaces. Subsequent advances in instrumentation, probe design, and methods significantly increased opportunities for SICM beyond recording topography. Hybridization of SICM with coincident characterization techniques such as optical microscopy and faradaic electrodes have brought SICM to the forefront as a tool for nanoscale chemical measurement for a wide range of applications. Modern approaches to SICM realize an important tool in analytical, bioanalytical, biophysical, and materials measurements, where significant opportunities remain for further exploration. In this review, we chronicle the development of SICM from the perspective of both the development of instrumentation and methods and the breadth of measurements performed.
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Affiliation(s)
- Cheng Zhu
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Kaixiang Huang
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Natasha P Siepser
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Lane A Baker
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
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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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Swiatlowska P, Sanchez-Alonso JL, Mansfield C, Scaini D, Korchev Y, Novak P, Gorelik J. Short-term angiotensin II treatment regulates cardiac nanomechanics via microtubule modifications. NANOSCALE 2020; 12:16315-16329. [PMID: 32720664 DOI: 10.1039/d0nr02474k] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Mechanical properties of single myocytes contribute to the whole heart performance, but the measurement of mechanics in living cells at high resolution with minimal force interaction remains challenging. Angiotensin II (AngII) is a peptide hormone that regulates a number of physiological functions, including heart performance. It has also been shown to contribute to cell mechanics by inducing cell stiffening. Using non-contact high-resolution Scanning Ion Conductance Microscopy (SICM), we determine simultaneously cell topography and membrane transverse Young's modulus (YM) by a constant pressure application through a nanopipette. While applying pressure, the vertical position is recorded and a deformation map is generated from which YM can be calculated and corrected for the uneven geometry. High resolution of this method also allows studying specific membrane subdomains, such as Z-grooves and crests. We found that short-term AngII treatment reduces the transversal YM in isolated adult rat cardiomyocytes acting via an AT1 receptor. Blocking either a TGF-β1 receptor or Rho kinase abolishes this effect. Analysis of the cytoskeleton showed that AngII depletes microtubules by decreasing long-lived detyrosinated and acetylated microtubule populations. Interestingly, in the failing cardiomyocytes, which are stiffer than controls, the short-term AngII treatment also reduces the YM, thus normalizing the mechanical state of cells. This suggests that the short-term softening effect of AngII on cardiac cells is opposite to the well-characterized long-term hypertrophic effect. In conclusion, we generate a precise nanoscale indication map of location-specific transverse cortical YM within the cell and this can substantially advance our understanding of cellular mechanics in a physiological environment, for example in isolated cardiac myocytes.
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Affiliation(s)
- Pamela Swiatlowska
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
| | - Jose L Sanchez-Alonso
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
| | - Catherine Mansfield
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
| | - Denis Scaini
- Department of Medicine, Imperial College London, London, UK and International School for Advanced Studies, Trieste, Italy
| | - Yuri Korchev
- Department of Medicine, Imperial College London, London, UK and Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Pavel Novak
- Department of Medicine, Imperial College London, London, UK and National University of Science and Technology, MISiS, Leninskiy prospect 4, Moscow, 119991, Russia
| | - Julia Gorelik
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
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Sanchez-Alonso JL, Loucks A, Schobesberger S, van Cromvoirt AM, Poulet C, Chowdhury RA, Trayanova N, Gorelik J. Nanoscale regulation of L-type calcium channels differentiates between ischemic and dilated cardiomyopathies. EBioMedicine 2020; 57:102845. [PMID: 32580140 PMCID: PMC7317229 DOI: 10.1016/j.ebiom.2020.102845] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/19/2020] [Accepted: 06/03/2020] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Subcellular localization and function of L-type calcium channels (LTCCs) play an important role in regulating contraction of cardiomyocytes. Understanding how this is affected by the disruption of transverse tubules during heart failure could lead to new insights into the disease. METHODS Cardiomyocytes were isolated from healthy donor hearts, as well as from patients with cardiomyopathies and with left ventricular assist devices. Scanning ion conductance and confocal microscopy was used to study membrane structures in the cells. Super-resolution scanning patch-clamp was used to examine LTCC function in different microdomains. Computational modeling predicted the impact of these changes to arrhythmogenesis at the whole-heart level. FINDINGS We showed that loss of structural organization in failing myocytes leads to re-distribution of functional LTCCs from the T-tubules to the sarcolemma. In ischemic cardiomyopathy, the increased LTCC open probability in the T-tubules depends on the phosphorylation by protein kinase A, whereas in dilated cardiomyopathy, the increased LTCC opening probability in the sarcolemma results from enhanced phosphorylation by calcium-calmodulin kinase II. LVAD implantation corrected LTCCs pathophysiological activity, although it did not improve their distribution. Using computational modeling in a 3D anatomically-realistic human ventricular model, we showed how LTCC location and activity can trigger heart rhythm disorders of different severity. INTERPRETATION Our findings demonstrate that LTCC redistribution and function differentiate between disease aetiologies. The subcellular changes observed in specific microdomains could be the consequence of the action of distinct protein kinases. FUNDING This work was supported by NIH grant (ROI-HL 126802 to NT-JG) and British Heart Foundation (grant RG/17/13/33173 to JG, project grant PG/16/17/32069 to RAC). Funders had no role in study design, data collection, data analysis, interpretation, writing of the report.
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Affiliation(s)
- Jose L Sanchez-Alonso
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Alexandra Loucks
- Department of Biomedical Engineering and Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sophie Schobesberger
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Ankie M van Cromvoirt
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Claire Poulet
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Rasheda A Chowdhury
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Natalia Trayanova
- Department of Biomedical Engineering and Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Julia Gorelik
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK.
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Pitoulis FG, Watson SA, Perbellini F, Terracciano CM. Myocardial slices come to age: an intermediate complexity in vitro cardiac model for translational research. Cardiovasc Res 2020; 116:1275-1287. [PMID: 31868875 PMCID: PMC7243278 DOI: 10.1093/cvr/cvz341] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/31/2019] [Accepted: 12/19/2019] [Indexed: 12/17/2022] Open
Abstract
Although past decades have witnessed significant reductions in mortality of heart failure together with advances in our understanding of its cellular, molecular, and whole-heart features, a lot of basic cardiac research still fails to translate into clinical practice. In this review we examine myocardial slices, a novel model in the translational arena. Myocardial slices are living ultra-thin sections of heart tissue. Slices maintain the myocardium's native function (contractility, electrophysiology) and structure (multicellularity, extracellular matrix) and can be prepared from animal and human tissue. The discussion begins with the history and current advances in the model, the different interlaboratory methods of preparation and their potential impact on results. We then contextualize slices' advantages and limitations by comparing it with other cardiac models. Recently, sophisticated methods have enabled slices to be cultured chronically in vitro while preserving the functional and structural phenotype. This is more timely now than ever where chronic physiologically relevant in vitro platforms for assessment of therapeutic strategies are urgently needed. We interrogate the technological developments that have permitted this, their limitations, and future directions. Finally, we look into the general obstacles faced by the translational field, and how implementation of research systems utilizing slices could help in resolving these.
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Affiliation(s)
- Fotios G Pitoulis
- Laboratory of Cell Electrophysiology, Department of Myocardial Function, Imperial College London, National Heart and Lung Institute, 4th Floor ICTEM Building Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Samuel A Watson
- Laboratory of Cell Electrophysiology, Department of Myocardial Function, Imperial College London, National Heart and Lung Institute, 4th Floor ICTEM Building Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Filippo Perbellini
- Laboratory of Cell Electrophysiology, Department of Myocardial Function, Imperial College London, National Heart and Lung Institute, 4th Floor ICTEM Building Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
- Hannover Medical School, Institute of Molecular and Translational Therapeutic Strategies, Hannover, Germany
| | - Cesare M Terracciano
- Laboratory of Cell Electrophysiology, Department of Myocardial Function, Imperial College London, National Heart and Lung Institute, 4th Floor ICTEM Building Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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7
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Studying signal compartmentation in adult cardiomyocytes. Biochem Soc Trans 2020; 48:61-70. [PMID: 32104883 PMCID: PMC7054744 DOI: 10.1042/bst20190247] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 01/31/2020] [Accepted: 02/04/2020] [Indexed: 02/04/2023]
Abstract
Multiple intra-cellular signalling pathways rely on calcium and 3′–5′ cyclic adenosine monophosphate (cAMP) to act as secondary messengers. This is especially true in cardiomyocytes which act as the force-producing units of the cardiac muscle and are required to react rapidly to environmental stimuli. The specificity of functional responses within cardiomyocytes and other cell types is produced by the organellar compartmentation of both calcium and cAMP. In this review, we assess the role of molecular localisation and relative contribution of active and passive processes in producing compartmentation. Active processes comprise the creation and destruction of signals, whereas passive processes comprise the release or sequestration of signals. Cardiomyocytes display a highly articulated membrane structure which displays significant cell-to-cell variability. Special attention is paid to the way in which cell membrane caveolae and the transverse-axial tubule system allow molecular localisation. We explore the effects of cell maturation, pathology and regional differences in the organisation of these processes. The subject of signal compartmentation has had a significant amount of attention within the cardiovascular field and has undergone a revolution over the past two decades. Advances in the area have been driven by molecular imaging using fluorescent dyes and genetically encoded constructs based upon fluorescent proteins. We also explore the use of scanning probe microscopy in the area. These techniques allow the analysis of molecular compartmentation within specific organellar compartments which gives researchers an entirely new perspective.
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Wright PT, Tsui SF, Francis AJ, MacLeod KT, Marston SB. Approaches to High-Throughput Analysis of Cardiomyocyte Contractility. Front Physiol 2020; 11:612. [PMID: 32733259 PMCID: PMC7362994 DOI: 10.3389/fphys.2020.00612] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 05/15/2020] [Indexed: 01/20/2023] Open
Abstract
The measurement of the contractile behavior of single cardiomyocytes has made a significant contribution to our understanding of the physiology and pathophysiology of the myocardium. However, the isolation of cardiomyocytes introduces various technical and statistical issues. Traditional video and fluorescence microscopy techniques based around conventional microscopy systems result in low-throughput experimental studies, in which single cells are studied over the course of a pharmacological or physiological intervention. We describe a new approach to these experiments made possible with a new piece of instrumentation, the CytoCypher High-Throughput System (CC-HTS). We can assess the shortening of sarcomeres, cell length, Ca2+ handling, and cellular morphology of almost 4 cells per minute. This increase in productivity means that batch-to-batch variation can be identified as a major source of variability. The speed of acquisition means that sufficient numbers of cells in each preparation can be assessed for multiple conditions reducing these batch effects. We demonstrate the different temporal scales over which the CC-HTS can acquire data. We use statistical analysis methods that compensate for the hierarchical effects of clustering within heart preparations and demonstrate a significant false-positive rate, which is potentially present in conventional studies. We demonstrate a more stringent way to perform these tests. The baseline morphological and functional characteristics of rat, mouse, guinea pig, and human cells are explored. Finally, we show data from concentration response experiments revealing the usefulness of the CC-HTS in such studies. We specifically focus on the effects of agents that directly or indirectly affect the activity of the motor proteins involved in the production of cardiomyocyte contraction. A variety of myocardial preparations with differing levels of complexity are in use (e.g., isolated muscle bundles, thin slices, perfused dual innervated isolated heart, and perfused ventricular wedge). All suffer from low throughput but can be regarded as providing independent data points in contrast to the clustering problems associated with isolated cell studies. The greater productivity and sampling power provided by CC-HTS may help to reestablish the utility of isolated cell studies, while preserving the unique insights provided by studying the contribution of the fundamental, cellular unit of myocardial contractility.
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