1
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Combémorel N, Cavell N, Tyser RCV. Early heart development: examining the dynamics of function-form emergence. Biochem Soc Trans 2024:BST20230546. [PMID: 38979619 DOI: 10.1042/bst20230546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 06/17/2024] [Accepted: 06/19/2024] [Indexed: 07/10/2024]
Abstract
During early embryonic development, the heart undergoes a remarkable and complex transformation, acquiring its iconic four-chamber structure whilst concomitantly contracting to maintain its essential function. The emergence of cardiac form and function involves intricate interplays between molecular, cellular, and biomechanical events, unfolding with precision in both space and time. The dynamic morphological remodelling of the developing heart renders it particularly vulnerable to congenital defects, with heart malformations being the most common type of congenital birth defect (∼35% of all congenital birth defects). This mini-review aims to give an overview of the morphogenetic processes which govern early heart formation as well as the dynamics and mechanisms of early cardiac function. Moreover, we aim to highlight some of the interplay between these two processes and discuss how recent findings and emerging techniques/models offer promising avenues for future exploration. In summary, the developing heart is an exciting model to gain fundamental insight into the dynamic relationship between form and function, which will augment our understanding of cardiac congenital defects and provide a blueprint for potential therapeutic strategies to treat disease.
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Affiliation(s)
- Noémie Combémorel
- Cambridge Stem Cell Institute, University of Cambridge, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, U.K
| | - Natasha Cavell
- Cambridge Stem Cell Institute, University of Cambridge, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, U.K
| | - Richard C V Tyser
- Cambridge Stem Cell Institute, University of Cambridge, Jeffrey Cheah Biomedical Centre, Cambridge CB2 0AW, U.K
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2
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Wiesinger A, Li J, Fokkert L, Bakker P, Verkerk AO, Christoffels VM, Boink GJJ, Devalla HD. A single cell transcriptional roadmap of human pacemaker cell differentiation. eLife 2022; 11:76781. [PMID: 36217819 PMCID: PMC9553210 DOI: 10.7554/elife.76781] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 08/16/2022] [Indexed: 12/26/2022] Open
Abstract
Each heartbeat is triggered by the sinoatrial node (SAN), the primary pacemaker of the heart. Studies in animal models have revealed that pacemaker cells share a common progenitor with the (pro)epicardium, and that the pacemaker cardiomyocytes further diversify into ‘transitional’, ‘tail’, and ‘head’ subtypes. However, the underlying molecular mechanisms, especially of human pacemaker cell development, are poorly understood. Here, we performed single cell RNA sequencing (scRNA-seq) and trajectory inference on human induced pluripotent stem cells (hiPSCs) differentiating to SAN-like cardiomyocytes (SANCMs) to construct a roadmap of transcriptional changes and lineage decisions. In differentiated SANCM, we identified distinct clusters that closely resemble different subpopulations of the in vivo SAN. Moreover, the presence of a side population of proepicardial cells suggested their shared ontogeny with SANCM, as also reported in vivo. Our results demonstrate that the divergence of SANCM and proepicardial lineages is determined by WNT signaling. Furthermore, we uncovered roles for TGFβ and WNT signaling in the branching of transitional and head SANCM subtypes, respectively. These findings provide new insights into the molecular processes involved in human pacemaker cell differentiation, opening new avenues for complex disease modeling in vitro and inform approaches for cell therapy-based regeneration of the SAN.
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Affiliation(s)
- Alexandra Wiesinger
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Jiuru Li
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Lianne Fokkert
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Priscilla Bakker
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Arie O Verkerk
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands.,Department of Experimental Cardiology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Vincent M Christoffels
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Gerard J J Boink
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands.,Department of Cardiology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Harsha D Devalla
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
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3
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Assembly of the Cardiac Pacemaking Complex: Electrogenic Principles of Sinoatrial Node Morphogenesis. J Cardiovasc Dev Dis 2021; 8:jcdd8040040. [PMID: 33917972 PMCID: PMC8068396 DOI: 10.3390/jcdd8040040] [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: 03/05/2021] [Revised: 03/31/2021] [Accepted: 04/05/2021] [Indexed: 11/24/2022] Open
Abstract
Cardiac pacemaker cells located in the sinoatrial node initiate the electrical impulses that drive rhythmic contraction of the heart. The sinoatrial node accounts for only a small proportion of the total mass of the heart yet must produce a stimulus of sufficient strength to stimulate the entire volume of downstream cardiac tissue. This requires balancing a delicate set of electrical interactions both within the sinoatrial node and with the downstream working myocardium. Understanding the fundamental features of these interactions is critical for defining vulnerabilities that arise in human arrhythmic disease and may provide insight towards the design and implementation of the next generation of potential cellular-based cardiac therapeutics. Here, we discuss physiological conditions that influence electrical impulse generation and propagation in the sinoatrial node and describe developmental events that construct the tissue-level architecture that appears necessary for sinoatrial node function.
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4
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Christoffels V, Jensen B. Cardiac Morphogenesis: Specification of the Four-Chambered Heart. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a037143. [PMID: 31932321 DOI: 10.1101/cshperspect.a037143] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Early heart morphogenesis involves a process in which embryonic precursor cells are instructed to form a cyclic contracting muscle tube connected to blood vessels, pumping fluid. Subsequently, the heart becomes structurally complex and its size increases several orders of magnitude to functionally keep up with the demands of the growing organism. Programmed transcriptional regulatory networks control the early steps of cardiac development. However, already during the early stages of its assembly, the heart tube starts to produce electrochemical potentials, contractions, and flow, which are transduced into signals that feed back into the process of morphogenesis itself. Heart morphogenesis, thus, involves the interplay between progressively changing genetic networks, function, and shape. Morphogenesis is evolutionarily conserved, but species-specific differences occur and in mouse, for instance, distinct phases of development become overlapping and compounded in an extremely fast gestation. Here, we review the early morphogenesis of the chambered heart that maintains a circulation supporting development of an organism rapidly growing in size and requirements.
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Affiliation(s)
- Vincent Christoffels
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam 1105AZ, The Netherlands
| | - Bjarke Jensen
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam 1105AZ, The Netherlands
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5
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Disruption of RHOA‐ROCK Signaling Results in Atrioventricular Block and Disturbed Development of the Putative Atrioventricular Node. Anat Rec (Hoboken) 2018; 302:83-92. [DOI: 10.1002/ar.23912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 02/07/2018] [Accepted: 02/25/2018] [Indexed: 12/27/2022]
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6
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Vicente Steijn R, Sedmera D, Blom NA, Jongbloed M, Kvasilova A, Nanka O. Apoptosis and epicardial contributions act as complementary factors in remodeling of the atrioventricular canal myocardium and atrioventricular conduction patterns in the embryonic chick heart. Dev Dyn 2018; 247:1033-1042. [PMID: 30152577 DOI: 10.1002/dvdy.24642] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/26/2018] [Accepted: 05/31/2018] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND During heart development, it has been hypothesized that apoptosis of atrioventricular canal myocardium and replacement by fibrous tissue derived from the epicardium are imperative to develop a mature atrioventricular conduction. To test this, apoptosis was blocked using an established caspase inhibitor and epicardial growth was delayed using the experimental epicardial inhibition model, both in chick embryonic hearts. RESULTS Chicken embryonic hearts were either treated with the peptide caspase inhibitor zVAD-fmk by intrapericardial injection in ovo (ED4) or underwent epicardial inhibition (ED2.5). Spontaneously beating embryonic hearts isolated (ED7-ED8) were then stained with voltage-sensitive dye Di-4-ANEPPS and imaged at 0.5-1 kHz. Apoptotic cells were quantified (ED5-ED7) by whole-mount LysoTracker Red and anti-active caspase 3 staining. zVAD-treated hearts showed a significantly increased proportion of immature (base to apex) activation patterns at ED8, including ventricular activation originating from the right atrioventricular junction, a pattern never observed in control hearts. zVAD-treated hearts showed decreased numbers of apoptotic cells in the atrioventricular canal myocardium at ED7. Hearts with delayed epicardial outgrowth showed also increased immature activation patterns at ED7.5 and ED8.5. However, the ventricular activation always originated from the left atrioventricular junction. Histological examination showed no changes in apoptosis rates, but a diminished presence of atrioventricular sulcus tissue compared with controls. CONCLUSIONS Apoptosis in the atrioventricular canal myocardium and controlled replacement of this myocardium by epicardially derived HCN4-/Trop1- sulcus tissue are essential determinants of mature ventricular activation pattern. Disruption can lead to persistence of accessory atrioventricular connections, forming a morphological substrate for ventricular pre-excitation. Developmental Dynamics 247:1033-1042, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Rebecca Vicente Steijn
- Department of Anatomy & Embryology, Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - David Sedmera
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic.,Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Nico A Blom
- Department of Pediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Monique Jongbloed
- Department of Anatomy & Embryology, Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Alena Kvasilova
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Ondrej Nanka
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
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7
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Vicente-Steijn R, Kelder TP, Tertoolen LG, Wisse LJ, Pijnappels DA, Poelmann RE, Schalij MJ, deRuiter MC, Gittenberger-de Groot AC, Jongbloed MRM. RHOA-ROCK signalling is necessary for lateralization and differentiation of the developing sinoatrial node. Cardiovasc Res 2018; 113:1186-1197. [PMID: 28899000 DOI: 10.1093/cvr/cvx104] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 07/03/2017] [Indexed: 01/16/2023] Open
Abstract
Aims RHOA-ROCK signalling regulates cell migration, proliferation, differentiation, and transcription. RHOA is expressed in the developing cardiac conduction system in chicken and mice. In early development, the entire sinus venosus myocardium, including both the transient left-sided and the definitive sinoatrial node (SAN), has pacemaker potential. Later, pacemaker potential is restricted to the right-sided SAN. Disruption of RHOA expression in adult mice causes arrhythmias including bradycardia and atrial fibrillation, the mechanism of which is unknown but presumed to affect the SAN. The aim of this study is to assess the role of RHOA-ROCK signalling in SAN development in the chicken heart. Methods and results ROCK signalling was inhibited chemically in embryonic chicken hearts using Y-27632. This prolonged the immature state of the sinus venosus myocardium, evidenced by up-regulation of the transcription factor ISL1, wide distribution of pacemaker potential, and significantly reduced heart rate. Furthermore ROCK inhibition caused aberrant expression of typical SAN genes: ROCK1, ROCK2, SHOX2, TBX3, TBX5, ISL1, HCN4, CX40, CAV3.1, and NKX2.5 and left-right asymmetry genes: PITX2C and NODAL. Anatomical abnormalities in pulmonary vein development were also observed. Patch clamp electrophysiology confirmed the immature phenotype of the SAN cells and a residual left-sided sinus venosus myocardium pacemaker-like potential. Conclusions RHOA-ROCK signalling is involved in establishing the right-sided SAN as the definitive pacemaker of the heart and restricts typical pacemaker gene expression to the right side of the sinus venosus myocardium.
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Affiliation(s)
- Rebecca Vicente-Steijn
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.,ICIN Netherlands Heart Institute, Utrecht, The Netherlands
| | - Tim P Kelder
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Leon G Tertoolen
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Lambertus J Wisse
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Daniël A Pijnappels
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Robert E Poelmann
- Sylvius Laboratory, Institute of Biology Leiden (IBL), Leiden University, Leiden, The Netherlands
| | - Martin J Schalij
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marco C deRuiter
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Adriana C Gittenberger-de Groot
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Monique R M Jongbloed
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
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8
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Carmona R, Ariza L, Cañete A, Muñoz-Chápuli R. Comparative developmental biology of the cardiac inflow tract. J Mol Cell Cardiol 2018; 116:155-164. [PMID: 29452155 DOI: 10.1016/j.yjmcc.2018.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/05/2018] [Accepted: 02/06/2018] [Indexed: 02/03/2023]
Abstract
The vertebrate heart receives the blood through the cardiac inflow tract. This area has experienced profound changes along the evolution of vertebrates; changes that have a reflection in the cardiac ontogeny. The development of the inflow tract involves dynamic changes due to the progressive addition of tissue derived from the secondary heart field. The inflow tract is the site where oxygenated blood coming from lungs is received separately from the systemic return, where the cardiac pacemaker is established and where the proepicardium develops. Differential cell migration towards the inflow tract breaks the symmetry of the primary heart tube and determines the direction of the cardiac looping. In air-breathing vertebrates, an inflow tract reorganization is essential to keep separate blood flows from systemic and pulmonary returns. Finally, the sinus venosus endocardium has recently been recognized as playing a role in the constitution of the coronary vasculature. Due to this developmental complexity, congenital anomalies of the inflow tract can cause severe cardiac diseases. We aimed to review the recent literature on the cellular and molecular mechanisms that regulate the morphogenesis of the cardiac inflow tract, together with comparative and evolutionary details, thus providing a basis for a better understanding of these mechanisms.
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Affiliation(s)
- Rita Carmona
- Department of Animal Biology, Faculty of Science, University of Málaga, Andalusian Center for Nanomedicine and Biotechnology (BIONAND), 29071 Málaga (Spain), Spain
| | - Laura Ariza
- Department of Animal Biology, Faculty of Science, University of Málaga, Andalusian Center for Nanomedicine and Biotechnology (BIONAND), 29071 Málaga (Spain), Spain
| | - Ana Cañete
- Department of Animal Biology, Faculty of Science, University of Málaga, Andalusian Center for Nanomedicine and Biotechnology (BIONAND), 29071 Málaga (Spain), Spain
| | - Ramón Muñoz-Chápuli
- Department of Animal Biology, Faculty of Science, University of Málaga, Andalusian Center for Nanomedicine and Biotechnology (BIONAND), 29071 Málaga (Spain), Spain.
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9
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Burkhard S, van Eif V, Garric L, Christoffels VM, Bakkers J. On the Evolution of the Cardiac Pacemaker. J Cardiovasc Dev Dis 2017; 4:jcdd4020004. [PMID: 29367536 PMCID: PMC5715705 DOI: 10.3390/jcdd4020004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 04/18/2017] [Accepted: 04/24/2017] [Indexed: 01/26/2023] Open
Abstract
The rhythmic contraction of the heart is initiated and controlled by an intrinsic pacemaker system. Cardiac contractions commence at very early embryonic stages and coordination remains crucial for survival. The underlying molecular mechanisms of pacemaker cell development and function are still not fully understood. Heart form and function show high evolutionary conservation. Even in simple contractile cardiac tubes in primitive invertebrates, cardiac function is controlled by intrinsic, autonomous pacemaker cells. Understanding the evolutionary origin and development of cardiac pacemaker cells will help us outline the important pathways and factors involved. Key patterning factors, such as the homeodomain transcription factors Nkx2.5 and Shox2, and the LIM-homeodomain transcription factor Islet-1, components of the T-box (Tbx), and bone morphogenic protein (Bmp) families are well conserved. Here we compare the dominant pacemaking systems in various organisms with respect to the underlying molecular regulation. Comparative analysis of the pathways involved in patterning the pacemaker domain in an evolutionary context might help us outline a common fundamental pacemaker cell gene programme. Special focus is given to pacemaker development in zebrafish, an extensively used model for vertebrate development. Finally, we conclude with a summary of highly conserved key factors in pacemaker cell development and function.
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Affiliation(s)
- Silja Burkhard
- Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands.
| | - Vincent van Eif
- Department of Medical Biology, Academic Medical Center Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Laurence Garric
- Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands.
| | - Vincent M Christoffels
- Department of Medical Biology, Academic Medical Center Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Jeroen Bakkers
- Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands.
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands.
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10
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Abstract
In past decades, growing evidence from basic and clinical researches reveal that small guanosine triphosphate binding protein ras homolog gene family, member A (RhoA) and its main effector Rho-associated kinase (ROCK) play central and complex roles in cardiovascular systems, and increasing RhoA and ROCK activity is associated with a broad range of cardiovascular diseases such as congestive heart failure, atherosclerosis, and hypertension. Favorable outcomes have been observed with ROCK inhibitors treatment. In this review, we briefly summarize the pathophysiological roles of RhoA/ROCK signaling pathway on cardiovascular system, displaying the potential benefits in the cardiovascular system with controlling RhoA/ROCK signaling pathway.
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11
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van Weerd JH, Christoffels VM. The formation and function of the cardiac conduction system. Development 2016; 143:197-210. [PMID: 26786210 DOI: 10.1242/dev.124883] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The cardiac conduction system (CCS) consists of distinctive components that initiate and conduct the electrical impulse required for the coordinated contraction of the cardiac chambers. CCS development involves complex regulatory networks that act in stage-, tissue- and dose-dependent manners, and recent findings indicate that the activity of these networks is sensitive to common genetic variants associated with cardiac arrhythmias. Here, we review how these findings have provided novel insights into the regulatory mechanisms and transcriptional networks underlying CCS formation and function.
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Affiliation(s)
- Jan Hendrik van Weerd
- Department of Anatomy, Embryology & Physiology, Academic Medical Center, Amsterdam 1105 AZ, The Netherlands
| | - Vincent M Christoffels
- Department of Anatomy, Embryology & Physiology, Academic Medical Center, Amsterdam 1105 AZ, The Netherlands
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12
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Watanabe M, Rollins AM, Polo-Parada L, Ma P, Gu S, Jenkins MW. Probing the Electrophysiology of the Developing Heart. J Cardiovasc Dev Dis 2016; 3:jcdd3010010. [PMID: 29367561 PMCID: PMC5715694 DOI: 10.3390/jcdd3010010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/08/2016] [Accepted: 03/10/2016] [Indexed: 12/14/2022] Open
Abstract
Many diseases that result in dysfunction and dysmorphology of the heart originate in the embryo. However, the embryonic heart presents a challenging subject for study: especially challenging is its electrophysiology. Electrophysiological maturation of the embryonic heart without disturbing its physiological function requires the creation and deployment of novel technologies along with the use of classical techniques on a range of animal models. Each tool has its strengths and limitations and has contributed to making key discoveries to expand our understanding of cardiac development. Further progress in understanding the mechanisms that regulate the normal and abnormal development of the electrophysiology of the heart requires integration of this functional information with the more extensively elucidated structural and molecular changes.
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Affiliation(s)
- Michiko Watanabe
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
- Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Andrew M Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Luis Polo-Parada
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65201, USA.
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65201, USA.
| | - Pei Ma
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Shi Gu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Michael W Jenkins
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
- Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, OH 44106, USA.
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13
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Kelder TP, Vicente-Steijn R, Poelmann RE, Mummery CL, DeRuiter MC, Jongbloed MRM. The avian embryo to study development of the cardiac conduction system. Differentiation 2016; 91:90-103. [PMID: 26856662 DOI: 10.1016/j.diff.2016.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 01/26/2016] [Indexed: 11/17/2022]
Abstract
The avian embryo has long been a popular model system in developmental biology. The easy accessibility of the embryo makes it particularly suitable for in ovo microsurgery and manipulation. Re-incubation of the embryo allows long-term follow-up of these procedures. The current review focuses on the variety of techniques available to study development of the cardiac conduction system in avian embryos. Based on the large amount of relevant data arising from experiments in avian embryos, we conclude that the avian embryo has and will continue to be a powerful model system to study development in general and the developing cardiac conduction system in particular.
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Affiliation(s)
- Tim P Kelder
- Anatomy & Embryology, Leiden University Medical Center, The Netherlands
| | - Rebecca Vicente-Steijn
- Anatomy & Embryology, Leiden University Medical Center, The Netherlands; Cardiology, Leiden University Medical Center, The Netherlands; ICIN Netherlands Heart Institute, Utrecht, The Netherlands
| | - Robert E Poelmann
- Cardiology, Leiden University Medical Center, The Netherlands; Integrative Zoology, Institute Biology, University Leiden, The Netherlands
| | | | - Marco C DeRuiter
- Anatomy & Embryology, Leiden University Medical Center, The Netherlands
| | - Monique R M Jongbloed
- Anatomy & Embryology, Leiden University Medical Center, The Netherlands; Cardiology, Leiden University Medical Center, The Netherlands.
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14
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Kelder TP, Duim SN, Vicente-Steijn R, Végh AMD, Kruithof BPT, Smits AM, van Bavel TC, Bax NAM, Schalij MJ, Gittenberger-de Groot AC, DeRuiter MC, Goumans MJ, Jongbloed MRM. The epicardium as modulator of the cardiac autonomic response during early development. J Mol Cell Cardiol 2015; 89:251-9. [PMID: 26527381 DOI: 10.1016/j.yjmcc.2015.10.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 10/14/2015] [Accepted: 10/20/2015] [Indexed: 12/29/2022]
Abstract
The cardiac autonomic nervous system (cANS) modulates heart rate, contraction force and conduction velocity. The embryonic chicken heart already responds to epinephrine prior to establishment of the cANS. The aim of this study was to define the regions of the heart that might participate in modulating the early autonomic response to epinephrine. Immunofluorescence analysis reveals expression of neural markers tubulin beta-3 chain and neural cell adhesion molecule in the epicardium during early development. In addition, expression of the β2 adrenergic receptor, the receptor for epinephrine, was found in the epicardium. Ex-ovo micro-electrode recordings in hearts with inhibition of epicardial outgrowth showed a significantly reduced response of the heart rate to epinephrine compared to control hearts. This study suggests a role for the epicardium as autonomic modulator during early cardiac development.
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Affiliation(s)
- Tim P Kelder
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Sjoerd N Duim
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Rebecca Vicente-Steijn
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands; Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands; ICIN Netherlands Heart Institute, Utrecht, The Netherlands
| | - Anna M D Végh
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Boudewijn P T Kruithof
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Anke M Smits
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Thomas C van Bavel
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands; Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Noortje A M Bax
- Department of Biomedical Engineering, Eindhoven University of Technology, The Netherlands
| | - Martin J Schalij
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Adriana C Gittenberger-de Groot
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands; Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marco C DeRuiter
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marie-José Goumans
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
| | - Monique R M Jongbloed
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands; Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
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15
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Kelder TP, Vicente-Steijn R, Harryvan TJ, Kosmidis G, Gittenberger-de Groot AC, Poelmann RE, Schalij MJ, DeRuiter MC, Jongbloed MRM. The sinus venosus myocardium contributes to the atrioventricular canal: potential role during atrioventricular node development? J Cell Mol Med 2015; 19:1375-89. [PMID: 25752780 PMCID: PMC4459851 DOI: 10.1111/jcmm.12525] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 11/27/2014] [Indexed: 11/29/2022] Open
Abstract
The presence of distinct electrophysiological pathways within the atrioventricular node (AVN) is a prerequisite for atrioventricular nodal reentrant tachycardia to occur. In this study, the different cell contributions that may account for the anatomical and functional heterogeneity of the AVN were investigated. To study the temporal development of the AVN, the expression pattern of ISL1, expressed in cardiac progenitor cells, was studied in sequential stages performing co-staining with myocardial markers (TNNI2 and NKX2-5) and HCN4 (cardiac conduction system marker). An ISL1+/TNNI2+/HCN4+ continuity between the myocardium of the sinus venosus and atrioventricular canal was identified in the region of the putative AVN, which showed a pacemaker-like phenotype based on single cell patch-clamp experiments. Furthermore, qPCR analysis showed that even during early development, different cell populations can be identified in the region of the putative AVN. Fate mapping was performed by in ovo vital dye microinjection. Embryos were harvested and analysed 24 and 48 hrs post-injection. These experiments showed incorporation of sinus venosus myocardium in the posterior region of the atrioventricular canal. The myocardium of the sinus venosus contributes to the atrioventricular canal. It is postulated that the myocardium of the sinus venosus contributes to nodal extensions or transitional cells of the AVN since these cells are located in the posterior region of the AVN. This finding may help to understand the origin of atrioventricular nodal reentrant tachycardia.
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Affiliation(s)
- Tim P Kelder
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Rebecca Vicente-Steijn
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Tom J Harryvan
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Georgios Kosmidis
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Adriana C Gittenberger-de Groot
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Rob E Poelmann
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Martin J Schalij
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marco C DeRuiter
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Monique R M Jongbloed
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
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Calkoen EE, Vicente-Steijn R, Hahurij ND, van Munsteren CJ, Roest AAW, DeRuiter MC, Steendijk P, Schalij MJ, Gittenberger-de Groot AC, Blom NA, Jongbloed MRM. Abnormal sinoatrial node development resulting from disturbed vascular endothelial growth factor signaling. Int J Cardiol 2014; 183:249-57. [PMID: 25700200 DOI: 10.1016/j.ijcard.2014.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/25/2014] [Accepted: 12/01/2014] [Indexed: 11/17/2022]
Abstract
BACKGROUND Sinus node dysfunction is frequently observed in patients with congenital heart disease (CHD). Variants in the Vascular Endothelial Growth Factor-A (VEGF) pathway are associated with CHD. In Vegf(120/120) mice, over-expressing VEGF120, a reduced sinoatrial node (SAN) volume was suggested. Aim of the study is to assess the effect of VEGF over-expression on SAN development and function. METHODS Heart rate was measured in Vegf(120/120) and wildtype (WT) embryos during high frequency ultrasound studies at embryonic day (E)12.5, 14.5 and 17.5 and by optical mapping at E12.5. Morphology was studied with several antibodies. SAN volume estimations were performed, and qualitative-PCR was used to quantify expression of genes in SAN tissues of WT and Vegf(120/120) embryos. RESULTS Heart rate was reduced in Vegf(120/120) compared with WT embryos during embryonic echocardiography (52 ± 17 versus 125 ± 31 beats per minute (bpm) at E12.5, p<0.001; 123 ± 37 vs 160 ± 29 bmp at E14.5, p=0.024; and 177 ± 30 vs 217 ± 34 bmp, at E17.5 p=0.017) and optical mapping (81 ± 5 vs 116 ± 8 bpm at E12.5; p=0.003). The SAN of mutant embryos was smaller and more vascularized, and showed increased expression of the fast conducting gap junction protein, Connexin43. CONCLUSIONS Over-expression of VEGF120 results in reduced heart rate and a smaller, less compact and hypervascularized SAN with increased expression of Connexin43. This indicates that VEGF is necessary for normal SAN development and function.
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Affiliation(s)
- Emmeline E Calkoen
- Department of Paediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands; Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Rebecca Vicente-Steijn
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Nathan D Hahurij
- Department of Paediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands; Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Conny J van Munsteren
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Arno A W Roest
- Department of Paediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marco C DeRuiter
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Paul Steendijk
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Martin J Schalij
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Adriana C Gittenberger-de Groot
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands; Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Nico A Blom
- Department of Paediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Monique R M Jongbloed
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands; Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
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Loirand G, Sauzeau V, Pacaud P. Small G Proteins in the Cardiovascular System: Physiological and Pathological Aspects. Physiol Rev 2013; 93:1659-720. [DOI: 10.1152/physrev.00021.2012] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Small G proteins exist in eukaryotes from yeast to human and constitute the Ras superfamily comprising more than 100 members. This superfamily is structurally classified into five families: the Ras, Rho, Rab, Arf, and Ran families that control a wide variety of cell and biological functions through highly coordinated regulation processes. Increasing evidence has accumulated to identify small G proteins and their regulators as key players of the cardiovascular physiology that control a large panel of cardiac (heart rhythm, contraction, hypertrophy) and vascular functions (angiogenesis, vascular permeability, vasoconstriction). Indeed, basal Ras protein activity is required for homeostatic functions in physiological conditions, but sustained overactivation of Ras proteins or spatiotemporal dysregulation of Ras signaling pathways has pathological consequences in the cardiovascular system. The primary object of this review is to provide a comprehensive overview of the current progress in our understanding of the role of small G proteins and their regulators in cardiovascular physiology and pathologies.
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Affiliation(s)
- Gervaise Loirand
- INSERM, UMR S1087; University of Nantes; and CHU Nantes, l'Institut du Thorax, Nantes, France
| | - Vincent Sauzeau
- INSERM, UMR S1087; University of Nantes; and CHU Nantes, l'Institut du Thorax, Nantes, France
| | - Pierre Pacaud
- INSERM, UMR S1087; University of Nantes; and CHU Nantes, l'Institut du Thorax, Nantes, France
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Islet1 is a direct transcriptional target of the homeodomain transcription factor Shox2 and rescues the Shox2-mediated bradycardia. Basic Res Cardiol 2013; 108:339. [PMID: 23455426 PMCID: PMC3597335 DOI: 10.1007/s00395-013-0339-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 01/31/2013] [Accepted: 02/08/2013] [Indexed: 01/10/2023]
Abstract
The heart's rhythm is initiated and regulated by a group of specialized cells in the sinoatrial node (SAN), the primary pacemaker of the heart. Abnormalities in the development of the SAN can result in irregular heart rates (arrhythmias). Although several of the critical genes important for SAN formation have been identified, our understanding of the transcriptional network controlling SAN development remains at a relatively early stage. The homeodomain transcription factor Shox2 is involved in the specification and patterning of the SAN. While the Shox2 knockout in mice results in embryonic lethality due to severe cardiac defects including improper SAN development, Shox2 knockdown in zebrafish causes a reduced heart rate (bradycardia). In order to gain deeper insight into molecular pathways involving Shox2, we compared gene expression levels in right atria of wildtype and Shox2 (-/-) hearts using microarray experiments and identified the LIM homeodomain transcription factor Islet1 (Isl1) as one of its putative target genes. The downregulation of Isl1 expression in Shox2 (-/-) hearts was confirmed and the affected region narrowed down to the SAN by whole-mount in situ hybridization. Using luciferase reporter assays and EMSA studies, we identified two specific SHOX2 binding sites within intron 2 of the ISL1 locus. We also provide functional evidence for Isl1 as a transcriptional target of Shox2 by rescuing the Shox2-mediated bradycardia phenotype with Isl1 using zebrafish as a model system. Our findings demonstrate a novel epistatic relationship between Shox2 and Isl1 in the heart with important developmental consequences for SAN formation and heart beat.
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Normal and abnormal development of the cardiac conduction system; implications for conduction and rhythm disorders in the child and adult. Differentiation 2012; 84:131-48. [DOI: 10.1016/j.diff.2012.04.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 04/16/2012] [Indexed: 11/20/2022]
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Jongbloed MRM, Vicente-Steijn R, Douglas YL, Wisse LJ, Mori K, Yokota Y, Bartelings MM, Schalij MJ, Mahtab EA, Poelmann RE, Gittenberger-De Groot AC. Expression of Id2 in the second heart field and cardiac defects in Id2 knock-out mice. Dev Dyn 2012; 240:2561-77. [PMID: 22012595 DOI: 10.1002/dvdy.22762] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The inhibitor of differentiation Id2 is expressed in mesoderm of the second heart field, which contributes myocardial and mesenchymal cells to the primary heart tube. The role of Id2 in cardiac development is insufficiently known. Heart development was studied in sequential developmental stages in Id2 wildtype and knockout mouse embryos. Expression patterns of Id2, MLC-2a, Nkx2.5, HCN4, and WT-1 were analyzed. Id2 is expressed in myocardial progenitor cells at the inflow and outflow tract, in the endocardial and epicardial lineage, and in neural crest cells. Id2 knockout embryos show severe cardiac defects including abnormal orientation of systemic and pulmonary drainage, abnormal myocardialization of systemic and pulmonary veins, hypoplasia of the sinoatrial node, large interatrial communications, ventricular septal defects, double outlet right ventricle, and myocardial hypoplasia. Our results indicate a role for Id2 in the second heart field contribution at both the arterial and the venous poles of the heart.
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Affiliation(s)
- M R M Jongbloed
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands.
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Ammirabile G, Tessari A, Pignataro V, Szumska D, Sutera Sardo F, Benes J, Balistreri M, Bhattacharya S, Sedmera D, Campione M. Pitx2 confers left morphological, molecular, and functional identity to the sinus venosus myocardium. Cardiovasc Res 2012; 93:291-301. [PMID: 22116619 PMCID: PMC3258653 DOI: 10.1093/cvr/cvr314] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 11/16/2011] [Accepted: 11/18/2011] [Indexed: 11/12/2022] Open
Abstract
AIMS The sinus venous myocardium, comprising the sinoatrial node (SAN) and sinus horns (SH), is a region subject to congenital malformations and cardiac arrhythmias. It differentiates from symmetric bilateral mesenchymal precursors, but morphological, molecular, and functional left/right differences are progressively established through development. The role of the laterality gene Pitx2 in this process is unknown. We aimed to elucidate the molecular events driving left/right patterning in the sinus venosus (SV) myocardium by using a myocardial Pitx2 knockout mouse. METHODS AND RESULTS We generated a myocardial specific Pitx2 knockout model (cTP mice). cTP embryos present several features of Pitx2 null, including right atrial isomerism with bilateral SANs and symmetric atrial entrance of the systemic veins. By in situ hybridization and optical mapping analysis, we compared throughout development the molecular and functional properties of the SV myocardium in wt and mutant embryos. We observed that Pitx2 prevents the expansion of the left-SAN primordium at the onset of its differentiation into myocardium; Pitx2 promotes expansion of the left SH through development; Pitx2 dose-dependently represses the autorhythmic properties of the left SV myocardium at mid-gestation (E14.5); Pitx2 modulates late foetal gene expression at the left SH-derived superior caval vein. CONCLUSION Pitx2 drives left/right patterning of the SV myocardium through multiple developmental steps. Overall, Pitx2 plays a crucial functional role by negatively modulating a nodal-type programme in the left SV myocardium.
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Affiliation(s)
- Grazia Ammirabile
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Alessandra Tessari
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Viviana Pignataro
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Dorota Szumska
- Department of Cardiovascular Medicine, Wellcome Trust Center for Human Genetics, Oxford, UK
| | - Fabio Sutera Sardo
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Jiri Benes
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague,Czech Republic
| | - Mariangela Balistreri
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Shoumo Bhattacharya
- Department of Cardiovascular Medicine, Wellcome Trust Center for Human Genetics, Oxford, UK
| | - David Sedmera
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague,Czech Republic
| | - Marina Campione
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
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Deciphering the pecking order of HCN4 expression in the developing heart: lessons from chicken. Heart Rhythm 2011; 8:1264-5. [PMID: 21699848 DOI: 10.1016/j.hrthm.2011.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Indexed: 11/23/2022]
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Vicente-Steijn R, Passier R, Wisse LJ, Schalij MJ, Poelmann RE, Gittenberger-de Groot AC, Jongbloed MRM. Funny current channel HCN4 delineates the developing cardiac conduction system in chicken heart. Heart Rhythm 2011; 8:1254-63. [PMID: 21421080 DOI: 10.1016/j.hrthm.2011.03.043] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2010] [Accepted: 03/14/2011] [Indexed: 10/18/2022]
Abstract
BACKGROUND Hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) in the mouse is expressed in the developing cardiac conduction system (CCS). In the sinoatrial node (SAN), HCN4 is the predominant isoform responsible for the funny current. To date, no data are available on HCN4 expression during chicken CCS development. OBJECTIVE The purpose of this study was to provide the full-length sequence of Hcn4 and describe its expression pattern during development in relation to the CCS in the chicken embryo. METHODS Hcn4 RNA expression was studied by in situ hybridization in sequential chick developmental stages (HH11-HH35) and immunohistochemical staining was conducted for the myocardial protein cardiac troponin I and the cardiac transcription factor Nkx2.5. RESULTS We obtained the full-length sequence of Hcn4 in chick. Hcn4 expression was observed early in development in the primary heart tube. At later stages, expression became restricted to transitional zones flanked by working myocardium, comprising the sinus venosus myocardium where the SAN develops, the atrioventricular canal myocardium, the primary fold (a myocardial zone between the developing ventricles), and the developing outflow tract. Further in development, Hcn4 expression was restricted to the SAN, the atrioventricular node, the common bundle, the bundle branches, and the internodal and atrioventricular ring myocardium. CONCLUSION We have identified Hcn4 as a marker of the developing CCS in the chick. The primary heart tube expresses Hcn4, which is later restricted to the transitional zones and eventually the elements of the mature CCS. Furthermore, we hypothesize that expression patterns during development may delineate potential arrhythmogenic sites in the adult heart.
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Affiliation(s)
- Rebecca Vicente-Steijn
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
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