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Pollitt EJG, Sánchez-Posada J, Snashall CM, Derrick CJ, Noël ES. Llgl1 mediates timely epicardial emergence and establishment of an apical laminin sheath around the trabeculating cardiac ventricle. Development 2024; 151:dev202482. [PMID: 38940292 PMCID: PMC11234374 DOI: 10.1242/dev.202482] [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: 10/26/2023] [Accepted: 05/31/2024] [Indexed: 06/29/2024]
Abstract
During heart development, the embryonic ventricle becomes enveloped by the epicardium, which adheres to the outer apical surface of the heart. This is concomitant with onset of ventricular trabeculation, where a subset of cardiomyocytes lose apicobasal polarity and delaminate basally from the ventricular wall. Llgl1 regulates the formation of apical cell junctions and apicobasal polarity, and we investigated its role in ventricular wall maturation. We found that llgl1 mutant zebrafish embryos exhibit aberrant apical extrusion of ventricular cardiomyocytes. While investigating apical cardiomyocyte extrusion, we identified a basal-to-apical shift in laminin deposition from the internal to the external ventricular wall. We find that epicardial cells express several laminin subunits as they adhere to the ventricle, and that the epicardium is required for laminin deposition on the ventricular surface. In llgl1 mutants, timely establishment of the epicardial layer is disrupted due to delayed emergence of epicardial cells, resulting in delayed apical deposition of laminin on the ventricular surface. Together, our analyses reveal an unexpected role for Llgl1 in correct timing of epicardial development, supporting integrity of the ventricular myocardial wall.
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Affiliation(s)
- Eric J. G. Pollitt
- School of Biosciences and Bateson Centre, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Juliana Sánchez-Posada
- School of Biosciences and Bateson Centre, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Corinna M. Snashall
- School of Biosciences and Bateson Centre, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Christopher J. Derrick
- School of Biosciences and Bateson Centre, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Emily S. Noël
- School of Biosciences and Bateson Centre, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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2
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Nielsen MS, van Opbergen CJM, van Veen TAB, Delmar M. The intercalated disc: a unique organelle for electromechanical synchrony in cardiomyocytes. Physiol Rev 2023; 103:2271-2319. [PMID: 36731030 PMCID: PMC10191137 DOI: 10.1152/physrev.00021.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 01/24/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
The intercalated disc (ID) is a highly specialized structure that connects cardiomyocytes via mechanical and electrical junctions. Although described in some detail by light microscopy in the 19th century, it was in 1966 that electron microscopy images showed that the ID represented apposing cell borders and provided detailed insight into the complex ID nanostructure. Since then, much has been learned about the ID and its molecular composition, and it has become evident that a large number of proteins, not all of them involved in direct cell-to-cell coupling via mechanical or gap junctions, reside at the ID. Furthermore, an increasing number of functional interactions between ID components are emerging, leading to the concept that the ID is not the sum of isolated molecular silos but an interacting molecular complex, an "organelle" where components work in concert to bring about electrical and mechanical synchrony. The aim of the present review is to give a short historical account of the ID's discovery and an updated overview of its composition and organization, followed by a discussion of the physiological implications of the ID architecture and the local intermolecular interactions. The latter will focus on both the importance of normal conduction of cardiac action potentials as well as the impact on the pathophysiology of arrhythmias.
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Affiliation(s)
- Morten S Nielsen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Chantal J M van Opbergen
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, New York, United States
| | - Toon A B van Veen
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mario Delmar
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, New York, United States
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3
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Sørhus E, Sørensen L, Grøsvik BE, Le Goff J, Incardona JP, Linbo TL, Baldwin DH, Karlsen Ø, Nordtug T, Hansen BH, Thorsen A, Donald CE, van der Meeren T, Robson W, Rowland SJ, Rasinger JD, Vikebø FB, Meier S. Crude oil exposure of early life stages of Atlantic haddock suggests threshold levels for developmental toxicity as low as 0.1 μg total polyaromatic hydrocarbon (TPAH)/L. MARINE POLLUTION BULLETIN 2023; 190:114843. [PMID: 36965263 DOI: 10.1016/j.marpolbul.2023.114843] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/10/2023] [Accepted: 03/14/2023] [Indexed: 06/18/2023]
Abstract
Atlantic haddock (Melanogrammus aeglefinus) embryos bind dispersed crude oil droplets to the eggshell and are consequently highly susceptible to toxicity from spilled oil. We established thresholds for developmental toxicity and identified any potential long-term or latent adverse effects that could impair the growth and survival of individuals. Embryos were exposed to oil for eight days (10, 80 and 300 μg oil/L, equivalent to 0.1, 0.8 and 3.0 μg TPAH/L). Acute and delayed mortality were observed at embryonic, larval, and juvenile stages with IC50 = 2.2, 0.39, and 0.27 μg TPAH/L, respectively. Exposure to 0.1 μg TPAH/L had no negative effect on growth or survival. However, yolk sac larvae showed significant reduction in the outgrowth (ballooning) of the cardiac ventricle in the absence of other extracardiac morphological defects. Due to this propensity for latent sublethal developmental toxicity, we recommend an effect threshold of 0.1 μg TPAH/L for risk assessment models.
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Affiliation(s)
- Elin Sørhus
- Institute of Marine Research, Bergen, Norway.
| | - Lisbet Sørensen
- Institute of Marine Research, Bergen, Norway; SINTEF Ocean AS, Postbox 4762, Torgarden, 7465 Trondheim, Norway
| | | | - Jérémie Le Goff
- ADn'tox, Bâtiment Recherche, Centre François Baclesse 3, Avenue du Général Harris, 14076 Caen Cedex 5, France
| | - John P Incardona
- Northwest Fisheries Science Center, National Oceanic and Atmospheric Administration, Seattle, WA, USA
| | - Tiffany L Linbo
- Northwest Fisheries Science Center, National Oceanic and Atmospheric Administration, Seattle, WA, USA
| | - David H Baldwin
- Office of Protected Resources, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA
| | | | - Trond Nordtug
- SINTEF Ocean AS, Postbox 4762, Torgarden, 7465 Trondheim, Norway
| | | | | | | | | | - William Robson
- Petroleum & Environmental Geochemistry Group, Biogeochemistry Research Centre, University of Plymouth, Plymouth PL4 8AA, Devon, UK
| | - Steven J Rowland
- Petroleum & Environmental Geochemistry Group, Biogeochemistry Research Centre, University of Plymouth, Plymouth PL4 8AA, Devon, UK
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4
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Capon SJ, Uribe V, Dominado N, Ehrlich O, Smith KA. Endocardial identity is established during early somitogenesis by Bmp signalling acting upstream of npas4l and etv2. Development 2022; 149:275317. [PMID: 35531980 PMCID: PMC9148566 DOI: 10.1242/dev.190421] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 03/28/2022] [Indexed: 12/28/2022]
Abstract
The endocardium plays important roles in the development and function of the vertebrate heart; however, few molecular markers of this tissue have been identified and little is known about what regulates its differentiation. Here, we describe the Gt(SAGFF27C); Tg(4xUAS:egfp) line as a marker of endocardial development in zebrafish. Transcriptomic comparison between endocardium and pan-endothelium confirms molecular distinction between these populations and time-course analysis suggests differentiation as early as eight somites. To investigate what regulates endocardial identity, we employed npas4l, etv2 and scl loss-of-function models. Endocardial expression is lost in npas4l mutants, significantly reduced in etv2 mutants and only modestly affected upon scl loss-of-function. Bmp signalling was also examined: overactivation of Bmp signalling increased endocardial expression, whereas Bmp inhibition decreased expression. Finally, epistasis experiments showed that overactivation of Bmp signalling was incapable of restoring endocardial expression in etv2 mutants. By contrast, overexpression of either npas4l or etv2 was sufficient to rescue endocardial expression upon Bmp inhibition. Together, these results describe the differentiation of the endocardium, distinct from vasculature, and place npas4l and etv2 downstream of Bmp signalling in regulating its differentiation. Summary: A zebrafish transgenic reporter of the endocardium is identified, permitting transcriptomic analysis and identification of new endocardial markers. Epistasis experiments demonstrate npas4l and etv2 act downstream of Bmp signalling to regulate endocardial differentiation.
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Affiliation(s)
- Samuel J Capon
- Division of Genomics of Development and Disease, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Veronica Uribe
- Department of Anatomy & Physiology, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Nicole Dominado
- Department of Anatomy & Physiology, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Ophelia Ehrlich
- Department of Anatomy & Physiology, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Kelly A Smith
- Division of Genomics of Development and Disease, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.,Department of Anatomy & Physiology, The University of Melbourne, Melbourne, Victoria 3010, Australia
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Gauvrit S, Bossaer J, Lee J, Collins MM. Modeling Human Cardiac Arrhythmias: Insights from Zebrafish. J Cardiovasc Dev Dis 2022; 9:jcdd9010013. [PMID: 35050223 PMCID: PMC8779270 DOI: 10.3390/jcdd9010013] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/23/2021] [Accepted: 12/25/2021] [Indexed: 12/13/2022] Open
Abstract
Cardiac arrhythmia, or irregular heart rhythm, is associated with morbidity and mortality and is described as one of the most important future public health challenges. Therefore, developing new models of cardiac arrhythmia is critical for understanding disease mechanisms, determining genetic underpinnings, and developing new therapeutic strategies. In the last few decades, the zebrafish has emerged as an attractive model to reproduce in vivo human cardiac pathologies, including arrhythmias. Here, we highlight the contribution of zebrafish to the field and discuss the available cardiac arrhythmia models. Further, we outline techniques to assess potential heart rhythm defects in larval and adult zebrafish. As genetic tools in zebrafish continue to bloom, this model will be crucial for functional genomics studies and to develop personalized anti-arrhythmic therapies.
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The zebrafish grime mutant uncovers an evolutionarily conserved role for Tmem161b in the control of cardiac rhythm. Proc Natl Acad Sci U S A 2021; 118:2018220118. [PMID: 33597309 DOI: 10.1073/pnas.2018220118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The establishment of cardiac function in the developing embryo is essential to ensure blood flow and, therefore, growth and survival of the animal. The molecular mechanisms controlling normal cardiac rhythm remain to be fully elucidated. From a forward genetic screen, we identified a unique mutant, grime, that displayed a specific cardiac arrhythmia phenotype. We show that loss-of-function mutations in tmem161b are responsible for the phenotype, identifying Tmem161b as a regulator of cardiac rhythm in zebrafish. To examine the evolutionary conservation of this function, we generated knockout mice for Tmem161b. Tmem161b knockout mice are neonatal lethal and cardiomyocytes exhibit arrhythmic calcium oscillations. Mechanistically, we find that Tmem161b is expressed at the cell membrane of excitable cells and live imaging shows it is required for action potential repolarization in the developing heart. Electrophysiology on isolated cardiomyocytes demonstrates that Tmem161b is essential to inhibit Ca2+ and K+ currents in cardiomyocytes. Importantly, Tmem161b haploinsufficiency leads to cardiac rhythm phenotypes, implicating it as a candidate gene in heritable cardiac arrhythmia. Overall, these data describe Tmem161b as a highly conserved regulator of cardiac rhythm that functions to modulate ion channel activity in zebrafish and mice.
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