1
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Stoyek MR, Doane SE, Dallaire SE, Long ZD, Ramia JM, Cassidy-Nolan DL, Poon KL, Brand T, Quinn TA. POPDC1 Variants Cause Atrioventricular Node Dysfunction and Arrhythmogenic Changes in Cardiac Electrophysiology and Intracellular Calcium Handling in Zebrafish. Genes (Basel) 2024; 15:280. [PMID: 38540339 PMCID: PMC10969970 DOI: 10.3390/genes15030280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 02/21/2024] [Accepted: 02/22/2024] [Indexed: 06/15/2024] Open
Abstract
Popeye domain-containing (POPDC) proteins selectively bind cAMP and mediate cellular responses to sympathetic nervous system (SNS) stimulation. The first discovered human genetic variant (POPDC1S201F) is associated with atrioventricular (AV) block, which is exacerbated by increased SNS activity. Zebrafish carrying the homologous mutation (popdc1S191F) display a similar phenotype to humans. To investigate the impact of POPDC1 dysfunction on cardiac electrophysiology and intracellular calcium handling, homozygous popdc1S191F and popdc1 knock-out (popdc1KO) zebrafish larvae and adult isolated popdc1S191F hearts were studied by functional fluorescent analysis. It was found that in popdc1S191F and popdc1KO larvae, heart rate (HR), AV delay, action potential (AP) and calcium transient (CaT) upstroke speed, and AP duration were less than in wild-type larvae, whereas CaT duration was greater. SNS stress by β-adrenergic receptor stimulation with isoproterenol increased HR, lengthened AV delay, slowed AP and CaT upstroke speed, and shortened AP and CaT duration, yet did not result in arrhythmias. In adult popdc1S191F zebrafish hearts, there was a higher incidence of AV block, slower AP upstroke speed, and longer AP duration compared to wild-type hearts, with no differences in CaT. SNS stress increased AV delay and led to further AV block in popdc1S191F hearts while decreasing AP and CaT duration. Overall, we have revealed that arrhythmogenic effects of POPDC1 dysfunction on cardiac electrophysiology and intracellular calcium handling in zebrafish are varied, but already present in early development, and that AV node dysfunction may underlie SNS-induced arrhythmogenesis associated with popdc1 mutation in adults.
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Affiliation(s)
- Matthew R. Stoyek
- Department of Physiology & Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada; (M.R.S.); (S.E.D.); (S.E.D.); (Z.D.L.); (J.M.R.); (D.L.C.-N.)
| | - Sarah E. Doane
- Department of Physiology & Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada; (M.R.S.); (S.E.D.); (S.E.D.); (Z.D.L.); (J.M.R.); (D.L.C.-N.)
| | - Shannon E. Dallaire
- Department of Physiology & Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada; (M.R.S.); (S.E.D.); (S.E.D.); (Z.D.L.); (J.M.R.); (D.L.C.-N.)
| | - Zachary D. Long
- Department of Physiology & Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada; (M.R.S.); (S.E.D.); (S.E.D.); (Z.D.L.); (J.M.R.); (D.L.C.-N.)
| | - Jessica M. Ramia
- Department of Physiology & Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada; (M.R.S.); (S.E.D.); (S.E.D.); (Z.D.L.); (J.M.R.); (D.L.C.-N.)
| | - Donovan L. Cassidy-Nolan
- Department of Physiology & Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada; (M.R.S.); (S.E.D.); (S.E.D.); (Z.D.L.); (J.M.R.); (D.L.C.-N.)
| | - Kar-Lai Poon
- National Heart & Lung Institute, Imperial College London, London W12 0NN, UK; (K.-L.P.); (T.B.)
| | - Thomas Brand
- National Heart & Lung Institute, Imperial College London, London W12 0NN, UK; (K.-L.P.); (T.B.)
| | - T. Alexander Quinn
- Department of Physiology & Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada; (M.R.S.); (S.E.D.); (S.E.D.); (Z.D.L.); (J.M.R.); (D.L.C.-N.)
- School of Biomedical Engineering, Dalhousie University, Halifax, NS B3H 4R2, Canada
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2
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Baillie JS, Gendernalik A, Garrity DM, Bark D, Quinn TA. The in vivo study of cardiac mechano-electric and mechano-mechanical coupling during heart development in zebrafish. Front Physiol 2023; 14:1086050. [PMID: 37007999 PMCID: PMC10060984 DOI: 10.3389/fphys.2023.1086050] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 03/08/2023] [Indexed: 03/18/2023] Open
Abstract
In the adult heart, acute adaptation of electrical and mechanical activity to changes in mechanical load occurs via feedback processes known as “mechano-electric coupling” and “mechano-mechanical coupling.” Whether this occurs during cardiac development is ill-defined, as acutely altering the heart’s mechanical load while measuring functional responses in traditional experimental models is difficult, as embryogenesis occurs in utero, making the heart inaccessible. These limitations can be overcome with zebrafish, as larvae develop in a dish and are nearly transparent, allowing for in vivo manipulation and measurement of cardiac structure and function. Here we present a novel approach for the in vivo study of mechano-electric and mechano-mechanical coupling in the developing zebrafish heart. This innovative methodology involves acute in vivo atrial dilation (i.e., increased atrial preload) in larval zebrafish by injection of a controlled volume into the venous circulation immediately upstream of the heart, combined with optical measurement of the acute electrical (change in heart rate) and mechanical (change in stroke area) response. In proof-of-concept experiments, we applied our new method to 48 h post-fertilisation zebrafish, which revealed differences between the electrical and mechanical response to atrial dilation. In response to an acute increase in atrial preload there is a large increase in atrial stroke area but no change in heart rate, demonstrating that in contrast to the fully developed heart, during early cardiac development mechano-mechanical coupling alone drives the adaptive increase in atrial output. Overall, in this methodological paper we present our new experimental approach for the study of mechano-electric and mechano-mechanical coupling during cardiac development and demonstrate its potential for understanding the essential adaptation of heart function to acute changes in mechanical load.
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Affiliation(s)
| | - Alex Gendernalik
- Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | | | - David Bark
- Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
- Mechanical Engineering, Colorado State University, Fort Collins, CO, United States
- Department of Pediatrics, Washington University in St. Louis, St. Louis, MO, United States
| | - T. Alexander Quinn
- Physiology & Biophysics, Dalhousie University, Halifax, NS, Canada
- Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
- *Correspondence: T. Alexander Quinn,
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3
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Ripplinger CM, Glukhov AV, Kay MW, Boukens BJ, Chiamvimonvat N, Delisle BP, Fabritz L, Hund TJ, Knollmann BC, Li N, Murray KT, Poelzing S, Quinn TA, Remme CA, Rentschler SL, Rose RA, Posnack NG. Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals. Am J Physiol Heart Circ Physiol 2022; 323:H1137-H1166. [PMID: 36269644 PMCID: PMC9678409 DOI: 10.1152/ajpheart.00439.2022] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. Although recent advances in cell-based models, including human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM), are contributing to our understanding of electrophysiology and arrhythmia mechanisms, preclinical animal studies of cardiovascular disease remain a mainstay. Over the past several decades, animal models of cardiovascular disease have advanced our understanding of pathological remodeling, arrhythmia mechanisms, and drug effects and have led to major improvements in pacing and defibrillation therapies. There exist a variety of methodological approaches for the assessment of cardiac electrophysiology and a plethora of parameters may be assessed with each approach. This guidelines article will provide an overview of the strengths and limitations of several common techniques used to assess electrophysiology and arrhythmia mechanisms at the whole animal, whole heart, and tissue level with a focus on small animal models. We also define key electrophysiological parameters that should be assessed, along with their physiological underpinnings, and the best methods with which to assess these parameters.
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Affiliation(s)
- Crystal M. Ripplinger
- 1Department of Pharmacology, University of California Davis School of Medicine, Davis, California
| | - Alexey V. Glukhov
- 2Department of Medicine, Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Matthew W. Kay
- 3Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Bastiaan J. Boukens
- 4Department Physiology, University Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands,5Department of Medical Biology, University of Amsterdam, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Nipavan Chiamvimonvat
- 1Department of Pharmacology, University of California Davis School of Medicine, Davis, California,6Department of Internal Medicine, University of California Davis School of Medicine, Davis, California,7Veterans Affairs Northern California Healthcare System, Mather, California
| | - Brian P. Delisle
- 8Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Larissa Fabritz
- 9University Center of Cardiovascular Science, University Heart and Vascular Center, University Hospital Hamburg-Eppendorf with DZHK Hamburg/Kiel/Luebeck, Germany,10Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Thomas J. Hund
- 11Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio,12Department of Biomedical Engineering, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Bjorn C. Knollmann
- 13Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Na Li
- 14Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Katherine T. Murray
- 15Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Steven Poelzing
- 16Virginia Tech Carilon School of Medicine, Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech, Roanoke, Virginia,17Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - T. Alexander Quinn
- 18Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada,19School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carol Ann Remme
- 20Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
| | - Stacey L. Rentschler
- 21Cardiovascular Division, Department of Medicine, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri
| | - Robert A. Rose
- 22Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada,23Department of Physiology and Pharmacology, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nikki G. Posnack
- 24Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Hospital, Washington, District of Columbia,25Department of Pediatrics, George Washington University School of Medicine, Washington, District of Columbia
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4
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Liu J, Kasuya G, Zempo B, Nakajo K. Two HCN4 Channels Play Functional Roles in the Zebrafish Heart. Front Physiol 2022; 13:901571. [PMID: 35846012 PMCID: PMC9281569 DOI: 10.3389/fphys.2022.901571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/31/2022] [Indexed: 11/13/2022] Open
Abstract
The HCN4 channel is essential for heart rate regulation in vertebrates by generating pacemaker potentials in the sinoatrial node. HCN4 channel abnormality may cause bradycardia and sick sinus syndrome, making it an important target for clinical research and drug discovery. The zebrafish is a popular animal model for cardiovascular research. They are potentially suitable for studying inherited heart diseases, including cardiac arrhythmia. However, it has not been determined how similar the ion channels that underlie cardiac automaticity are in zebrafish and humans. In the case of HCN4, humans have one gene, whereas zebrafish have two ortholog genes (DrHCN4 and DrHCN4L; ‘Dr’ referring to Danio rerio). However, it is not known whether the two HCN4 channels have different physiological functions and roles in heart rate regulation. In this study, we characterized the biophysical properties of the two zebrafish HCN4 channels in Xenopus oocytes and compared them to those of the human HCN4 channel. We found that they showed different gating properties: DrHCN4L currents showed faster activation kinetics and a more positively shifted G-V curve than did DrHCN4 and human HCN4 currents. We made chimeric channels of DrHCN4 and DrHCN4L and found that cytoplasmic domains were determinants for the faster activation and the positively shifted G-V relationship in DrHCN4L. The use of a dominant-negative HCN4 mutant confirmed that DrHCN4 and DrHCN4L can form a heteromultimeric channel in Xenopus oocytes. Next, we confirmed that both are sensitive to common HCN channel inhibitors/blockers including Cs+, ivabradine, and ZD7288. These HCN inhibitors successfully lowered zebrafish heart rate during early embryonic stages. Finally, we knocked down the HCN4 genes using antisense morpholino and found that knocking down either or both of the HCN4 channels caused a temporal decrease in heart rate and tended to cause pericardial edema. These findings suggest that both DrHCN4 and DrHCN4L play a significant role in zebrafish heart rate regulation.
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5
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Sacconi L, Silvestri L, Rodríguez EC, Armstrong GA, Pavone FS, Shrier A, Bub G. KHz-rate volumetric voltage imaging of the whole Zebrafish heart. BIOPHYSICAL REPORTS 2022; 2:100046. [PMID: 36425080 PMCID: PMC9680780 DOI: 10.1016/j.bpr.2022.100046] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/31/2022] [Indexed: 05/11/2023]
Abstract
Fast volumetric imaging is essential for understanding the function of excitable tissues such as those found in the brain and heart. Measuring cardiac voltage transients in tissue volumes is challenging, especially at the high spatial and temporal resolutions needed to give insight to cardiac function. We introduce a new imaging modality based on simultaneous illumination of multiple planes in the tissue and parallel detection with multiple cameras, avoiding compromises inherent in any scanning approach. The system enables imaging of voltage transients in situ, allowing us, for the first time to our knowledge, to map voltage activity in the whole heart volume at KHz rates. The high spatiotemporal resolution of our method enabled the observation of novel dynamics of electrical propagation through the zebrafish atrioventricular canal.
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Affiliation(s)
- Leonardo Sacconi
- European Laboratory for Non-linear Spectroscopy, and National Institute of Optics, National Research Council, Sesto Fiorentino, Italy
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Medical Faculty, University of Freiburg, Freiburg, Germany
- Corresponding author
| | - Ludovico Silvestri
- European Laboratory for Non-linear Spectroscopy, and National Institute of Optics, National Research Council, Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Florence, Italy
| | | | - Gary A.B. Armstrong
- Department of Neurology and Neurosurgery, McGill University, Montreal, Canada
| | - Francesco S. Pavone
- European Laboratory for Non-linear Spectroscopy, and National Institute of Optics, National Research Council, Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Florence, Italy
| | - Alvin Shrier
- Department of Physiology, McGill University, Montreal, Canada
| | - Gil Bub
- Department of Physiology, McGill University, Montreal, Canada
- Corresponding author
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6
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Stoyek MR, MacDonald EA, Mantifel M, Baillie JS, Selig BM, Croll RP, Smith FM, Quinn TA. Drivers of Sinoatrial Node Automaticity in Zebrafish: Comparison With Mechanisms of Mammalian Pacemaker Function. Front Physiol 2022; 13:818122. [PMID: 35295582 PMCID: PMC8919049 DOI: 10.3389/fphys.2022.818122] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/21/2022] [Indexed: 12/13/2022] Open
Abstract
Cardiac excitation originates in the sinoatrial node (SAN), due to the automaticity of this distinct region of the heart. SAN automaticity is the result of a gradual depolarisation of the membrane potential in diastole, driven by a coupled system of transarcolemmal ion currents and intracellular Ca2+ cycling. The frequency of SAN excitation determines heart rate and is under the control of extra- and intracardiac (extrinsic and intrinsic) factors, including neural inputs and responses to tissue stretch. While the structure, function, and control of the SAN have been extensively studied in mammals, and some critical aspects have been shown to be similar in zebrafish, the specific drivers of zebrafish SAN automaticity and the response of its excitation to vagal nerve stimulation and mechanical preload remain incompletely understood. As the zebrafish represents an important alternative experimental model for the study of cardiac (patho-) physiology, we sought to determine its drivers of SAN automaticity and the response to nerve stimulation and baseline stretch. Using a pharmacological approach mirroring classic mammalian experiments, along with electrical stimulation of intact cardiac vagal nerves and the application of mechanical preload to the SAN, we demonstrate that the principal components of the coupled membrane- Ca2+ pacemaker system that drives automaticity in mammals are also active in the zebrafish, and that the effects of extra- and intracardiac control of heart rate seen in mammals are also present. Overall, these results, combined with previously published work, support the utility of the zebrafish as a novel experimental model for studies of SAN (patho-) physiological function.
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Affiliation(s)
- Matthew R. Stoyek
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Eilidh A. MacDonald
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Melissa Mantifel
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Jonathan S. Baillie
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Bailey M. Selig
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Roger P. Croll
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Frank M. Smith
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - T. Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
- *Correspondence: T. Alexander Quinn,
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7
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Baillie JS, Stoyek MR, Quinn TA. Seeing the Light: The Use of Zebrafish for Optogenetic Studies of the Heart. Front Physiol 2021; 12:748570. [PMID: 35002753 PMCID: PMC8733579 DOI: 10.3389/fphys.2021.748570] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/19/2021] [Indexed: 11/13/2022] Open
Abstract
Optogenetics, involving the optical measurement and manipulation of cellular activity with genetically encoded light-sensitive proteins ("reporters" and "actuators"), is a powerful experimental technique for probing (patho-)physiological function. Originally developed as a tool for neuroscience, it has now been utilized in cardiac research for over a decade, providing novel insight into the electrophysiology of the healthy and diseased heart. Among the pioneering cardiac applications of optogenetic actuators were studies in zebrafish, which first demonstrated their use for precise spatiotemporal control of cardiac activity. Zebrafish were also adopted early as an experimental model for the use of optogenetic reporters, including genetically encoded voltage- and calcium-sensitive indicators. Beyond optogenetic studies, zebrafish are becoming an increasingly important tool for cardiac research, as they combine many of the advantages of integrative and reduced experimental models. The zebrafish has striking genetic and functional cardiac similarities to that of mammals, its genome is fully sequenced and can be modified using standard techniques, it has been used to recapitulate a variety of cardiac diseases, and it allows for high-throughput investigations. For optogenetic studies, zebrafish provide additional advantages, as the whole zebrafish heart can be visualized and interrogated in vivo in the transparent, externally developing embryo, and the relatively small adult heart allows for in situ cell-specific observation and control not possible in mammals. With the advent of increasingly sophisticated fluorescence imaging approaches and methods for spatially-resolved light stimulation in the heart, the zebrafish represents an experimental model with unrealized potential for cardiac optogenetic studies. In this review we summarize the use of zebrafish for optogenetic investigations in the heart, highlighting their specific advantages and limitations, and their potential for future cardiac research.
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Affiliation(s)
- Jonathan S. Baillie
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Matthew R. Stoyek
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - T. Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
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8
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Abu Nahia K, Migdał M, Quinn TA, Poon KL, Łapiński M, Sulej A, Liu J, Mondal SS, Pawlak M, Bugajski Ł, Piwocka K, Brand T, Kohl P, Korzh V, Winata C. Genomic and physiological analyses of the zebrafish atrioventricular canal reveal molecular building blocks of the secondary pacemaker region. Cell Mol Life Sci 2021; 78:6669-6687. [PMID: 34557935 PMCID: PMC8558220 DOI: 10.1007/s00018-021-03939-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 08/06/2021] [Accepted: 09/10/2021] [Indexed: 01/06/2023]
Abstract
The atrioventricular canal (AVC) is the site where key structures responsible for functional division between heart regions are established, most importantly, the atrioventricular (AV) conduction system and cardiac valves. To elucidate the mechanism underlying AVC development and function, we utilized transgenic zebrafish line sqet31Et expressing EGFP in the AVC to isolate this cell population and profile its transcriptome at 48 and 72 hpf. The zebrafish AVC transcriptome exhibits hallmarks of mammalian AV node, including the expression of genes implicated in its development and those encoding connexins forming low conductance gap junctions. Transcriptome analysis uncovered protein-coding and noncoding transcripts enriched in AVC, which have not been previously associated with this structure, as well as dynamic expression of epithelial-to-mesenchymal transition markers and components of TGF-β, Notch, and Wnt signaling pathways likely reflecting ongoing AVC and valve development. Using transgenic line Tg(myl7:mermaid) encoding voltage-sensitive fluorescent protein, we show that abolishing the pacemaker-containing sinoatrial ring (SAR) through Isl1 loss of function resulted in spontaneous activation in the AVC region, suggesting that it possesses inherent automaticity although insufficient to replace the SAR. The SAR and AVC transcriptomes express partially overlapping species of ion channels and gap junction proteins, reflecting their distinct roles. Besides identifying conserved aspects between zebrafish and mammalian conduction systems, our results established molecular hallmarks of the developing AVC which underlies its role in structural and electrophysiological separation between heart chambers. This data constitutes a valuable resource for studying AVC development and function, and identification of novel candidate genes implicated in these processes.
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Affiliation(s)
- Karim Abu Nahia
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Maciej Migdał
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kar-Lai Poon
- Institute of Molecular and Cell Biology, 61 Biopolis Dr, Singapore , Singapore.,Developmental Dynamics, National Heart and Lung Institute, Imperial College London, London, UK
| | - Maciej Łapiński
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Agata Sulej
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Jiandong Liu
- McAllister Heart Institute, University of North Carolina, Chapel Hill, USA
| | - Shamba S Mondal
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Michał Pawlak
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | | | | | - Thomas Brand
- Developmental Dynamics, National Heart and Lung Institute, Imperial College London, London, UK
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Centre, Faculty of Medicine, and Faculty of Engineering, University of Freiburg, Freiburg im Breisgau, Germany
| | - Vladimir Korzh
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.
| | - Cecilia Winata
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.
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9
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Observing and Manipulating Cell-Specific Cardiac Function with Light. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021. [PMID: 33398827 DOI: 10.1007/978-981-15-8763-4_24] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
The heart is a complex multicellular organ comprising both cardiomyocytes (CM), which make up the majority of the cardiac volume, and non-myocytes (NM), which represent the majority of cardiac cells. CM drive the pumping action of the heart, triggered via rhythmic electrical activity. NM, on the other hand, have many essential functions including generating extracellular matrix, regulating CM activity, and aiding in repair following injury. NM include neurons and interstitial, immune, and endothelial cells. Understanding the role of specific cell types and their interactions with one another may be key to developing new therapies with minimal side effects to treat cardiac disease. However, assessing cell-type-specific behavior in situ using standard techniques is challenging. Optogenetics enables population-specific observation and control, facilitating studies into the role of specific cell types and subtypes. Optogenetic models targeting the most important cardiac cell types have been generated and used to investigate non-canonical roles of those cell populations, e.g., to better understand how cardiac pacing occurs and to assess potential translational possibilities of optogenetics. So far, cardiac optogenetic studies have primarily focused on validating models and tools in the healthy heart. The field is now in a position where animal models and tools should be utilized to improve our understanding of the complex heterocellular nature of the heart, how this changes in disease, and from there to enable the development of cell-specific therapies and improved treatments.
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10
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MacDonald EA, Rose RA, Quinn TA. Neurohumoral Control of Sinoatrial Node Activity and Heart Rate: Insight From Experimental Models and Findings From Humans. Front Physiol 2020; 11:170. [PMID: 32194439 PMCID: PMC7063087 DOI: 10.3389/fphys.2020.00170] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 02/13/2020] [Indexed: 12/22/2022] Open
Abstract
The sinoatrial node is perhaps one of the most important tissues in the entire body: it is the natural pacemaker of the heart, making it responsible for initiating each-and-every normal heartbeat. As such, its activity is heavily controlled, allowing heart rate to rapidly adapt to changes in physiological demand. Control of sinoatrial node activity, however, is complex, occurring through the autonomic nervous system and various circulating and locally released factors. In this review we discuss the coupled-clock pacemaker system and how its manipulation by neurohumoral signaling alters heart rate, considering the multitude of canonical and non-canonical agents that are known to modulate sinoatrial node activity. For each, we discuss the principal receptors involved and known intracellular signaling and protein targets, highlighting gaps in our knowledge and understanding from experimental models and human studies that represent areas for future research.
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Affiliation(s)
- Eilidh A MacDonald
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Robert A Rose
- Cumming School of Medicine, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada.,School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
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