A Role for the Cytoskeleton in Heart Looping

Over the past 10 years, key genes involved in specification of left-right laterality pathways in the embryo have been defined. The read-out for misexpression of laterality genes is usually the direction of heart looping. The question of how dextral looping direction occurred mechanistically and how the heart tube bends remains unknown. It is becoming clear from our experiments and those of others that left-right differences in cell proliferation in the second heart field (anterior heart field) drives the dextral direction. Evidence is accumulating that the cytoskeleton is at the center of laterality, and the bending and rotational forces associated with heart looping. If laterality pathways are modulated upstream, the cytoskeleton, including nonmuscle myosin II (NMHC-II), is altered downstream within the cardiomyocytes, leading to looping abnormalities. The cytoskeleton is associated with important mechanosensing and signaling pathways in cell biology and development. The initiation of blood flow during the looping period and the inherent stresses associated with increasing volumes of blood flowing into the heart may help to potentiate the process. In recent years, the steps involved in this central and complex process of heart development that is the basis of numerous congenital heart defects are being unraveled.

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Cardiac embryogenesis

ESC CardioMed ◽

10.1093/med/9780198784906.003.0004_update_001 ◽

2018 ◽

pp. 33-36

Author(s):

Robert G. Kelly

Keyword(s):

Progenitor Cells ◽

Progenitor Cell ◽

Congenital Heart ◽

Heart Defects ◽

Embryonic Heart ◽

Heart Tube ◽

Second Heart Field ◽

Heart Field ◽

Cell Niche ◽

The Right

The embryonic heart forms in anterior lateral splanchnic mesoderm and is derived from Mesp1-expressing progenitor cells. During embryonic folding, the earliest differentiating progenitor cells form the linear heart tube in the ventral midline. The heart tube extends in length and loops to the right as new myocardium is progressively added at the venous and arterial poles from multipotent second heart field cardiovascular progenitor cells in contiguous pharyngeal mesoderm. While the linear heart tube gives rise to the left ventricle, the right ventricle, outflow tract, and a large part of atrial myocardium are derived from the second heart field. Progressive myocardial differentiation is controlled by intercellular signals within the progenitor cell niche. The embryonic heart is the template for septation and growth of the four-chambered definitive heart and defects in progenitor cell deployment result in a spectrum of common forms of congenital heart defects.

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Hey2 restricts cardiac progenitor addition to the developing heart

10.1101/199638 ◽

2017 ◽

Author(s):

Natalie Gibb ◽

Savo Lazic ◽

Ashish R. Deshwar ◽

Xuefei Yuan ◽

Michael D. Wilson ◽

...

Keyword(s):

Heart Development ◽

Heart Defects ◽

Myocardial Cell ◽

Cell Number ◽

Tube Formation ◽

Heart Tube ◽

Cardiac Progenitors ◽

Developing Heart ◽

Heart Field ◽

A Cell

ABSTRACTA key event in vertebrate heart development is the timely addition of second heart field (SHF) progenitor cells to the poles of the heart tube. This accretion process must occur to the proper extent to prevent a spectrum of congenital heart defects (CHDs). However, the factors that regulate this critical process are poorly understood. Here we demonstrate that Hey2, a bHLH transcriptional repressor, restricts SHF progenitor accretion to the zebrafish heart. hey2 expression demarcated a distinct domain within the cardiac progenitor population. In the absence of Hey2 function an increase in myocardial cell number and SHF progenitors was observed. We found that Hey2 limited proliferation of SHF-derived cardiomyocytes in a cell-autonomous manner, prior to heart tube formation, and further restricted the developmental window over which SHF progenitors were deployed to the heart. Taken together, our data suggests a role for Hey2 in controlling the proliferative capacity and cardiac contribution of late-differentiating cardiac progenitors.

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Cardiac embryogenesis

ESC CardioMed ◽

10.1093/med/9780198784906.003.0004 ◽

2018 ◽

pp. 33-36

Author(s):

Robert G. Kelly

Keyword(s):

Progenitor Cells ◽

Progenitor Cell ◽

Congenital Heart ◽

Heart Defects ◽

Embryonic Heart ◽

Heart Tube ◽

Second Heart Field ◽

Heart Field ◽

Cell Niche ◽

The Right

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Outflow Tract Formation—Embryonic Origins of Conotruncal Congenital Heart Disease

Journal of Cardiovascular Development and Disease ◽

10.3390/jcdd8040042 ◽

2021 ◽

Vol 8 (4) ◽

pp. 42

Author(s):

Sonia Stefanovic ◽

Heather C. Etchevers ◽

Stéphane Zaffran

Keyword(s):

Congenital Heart ◽

Cardiac Development ◽

Heart Defects ◽

Dynamic Structure ◽

Cell Types ◽

Outflow Tract ◽

Heart Tube ◽

Heart Field ◽

Multiple Cell ◽

The Many

Anomalies in the cardiac outflow tract (OFT) are among the most frequent congenital heart defects (CHDs). During embryogenesis, the cardiac OFT is a dynamic structure at the arterial pole of the heart. Heart tube elongation occurs by addition of cells from pharyngeal, splanchnic mesoderm to both ends. These progenitor cells, termed the second heart field (SHF), were first identified twenty years ago as essential to the growth of the forming heart tube and major contributors to the OFT. Perturbation of SHF development results in common forms of CHDs, including anomalies of the great arteries. OFT development also depends on paracrine interactions between multiple cell types, including myocardial, endocardial and neural crest lineages. In this publication, dedicated to Professor Andriana Gittenberger-De Groot and her contributions to the field of cardiac development and CHDs, we review some of her pioneering studies of OFT development with particular interest in the diverse origins of the many cell types that contribute to the OFT. We also discuss the clinical implications of selected key findings for our understanding of the etiology of CHDs and particularly OFT malformations.

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Lamb1a regulates atrial growth by limiting excessive, contractility-dependent second heart field addition during zebrafish heart development

10.1101/2021.03.10.434727 ◽

2021 ◽

Author(s):

Christopher J. Derrick ◽

Eric J. G. Pollitt ◽

Ashley Sanchez Sevilla Uruchurtu ◽

Farah Hussein ◽

Emily S. Noёl

Keyword(s):

Heart Development ◽

Cardiac Development ◽

Basement Membranes ◽

Atrioventricular Canal ◽

Cardiac Morphogenesis ◽

Heart Morphogenesis ◽

Second Heart Field ◽

Heart Field ◽

Heart Size ◽

Zebrafish Heart

AbstractDuring early vertebrate heart development, the heart transitions from a linear tube to a complex asymmetric structure. This process includes looping of the tube and ballooning of the emerging cardiac chambers, which occur simultaneously with growth of the heart. A key driver of cardiac growth is deployment of cells from the Second Heart Field (SHF) into both poles of the heart, with cardiac morphogenesis and growth intimately linked in heart development. Laminin is a core component of extracellular matrix (ECM) basement membranes, and although mutations in specific laminin subunits are linked with a variety of cardiac abnormalities, including congenital heart disease and dilated cardiomyopathy, no role for laminin has been identified in early vertebrate heart morphogenesis. We identified dynamic, tissue-specific expression of laminin subunit genes in the developing zebrafish heart, supporting a role for laminins in heart morphogenesis.lamb1amutants exhibit cardiomegaly from 2dpf onwards, with subsequent progressive defects in cardiac morphogenesis characterised by a failure of the chambers to compact around the developing atrioventricular canal. We show that loss oflamb1aresults in excess addition of SHF cells to the atrium, revealing that Lamb1a functions to limit heart size during cardiac development by restricting SHF addition to the venous pole.lamb1amutants exhibit hallmarks of altered haemodynamics, and specifically blocking cardiac contractility inlamb1amutants rescues heart size and atrial SHF addition. Furthermore, we identify that FGF and RA signalling, two conserved pathways promoting SHF addition, are regulated by heart contractility and are dysregulated inlamb1amutants, suggesting that laminin mediates interactions between SHF deployment, heart biomechanics, and biochemical signalling during heart development. Together, this describes the first requirement for laminins in early vertebrate heart morphogenesis, reinforcing the importance of specialised ECM composition in cardiac development.

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Temporally Distinct Six2 -Positive Second Heart Field Progenitors Regulate Mammalian Heart Development and Disease

Cell Reports ◽

10.1016/j.celrep.2017.01.002 ◽

2017 ◽

Vol 18 (4) ◽

pp. 1019-1032 ◽

Cited By ~ 24

Author(s):

Zhengfang Zhou ◽

Jingying Wang ◽

Chaoshe Guo ◽

Weiting Chang ◽

Jian Zhuang ◽

...

Keyword(s):

Heart Development ◽

Second Heart Field ◽

Mammalian Heart ◽

Heart Field

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Continuous addition of progenitors forms the cardiac ventricle in zebrafish

10.1101/230649 ◽

2017 ◽

Author(s):

Anastasia Felker ◽

Karin D. Prummel ◽

Anne M. Merks ◽

Michaela Mickoleit ◽

Eline C. Brombacher ◽

...

Keyword(s):

Heart Development ◽

High Speed ◽

Continuous Process ◽

Late Phase ◽

Lineage Tracing ◽

Heart Tube ◽

High Speed Imaging ◽

Lateral Plate ◽

Cardiac Ventricle ◽

Heart Field

AbstractThe vertebrate heart develops from several progenitor lineages. After early-differentiating first heart field (FHF) progenitors form the linear heart tube, late-differentiating second heart field (SHF) progenitors extend atrium, ventricle, and form the inflow and outflow tracts (IFT/OFT). However, the position and migration of late-differentiating progenitors during heart formation remains unclear. Here, we tracked zebrafish heart development using transgenics based on the cardiopharyngeal transcription factor gene tbx1. Live-imaging uncovered a tbx1 reporter-expressing cell sheath that from anterior lateral plate mesoderm continuously disseminates towards the forming heart tube. High-speed imaging and optogenetic lineage tracing corroborated that the zebrafish ventricle forms through continuous addition from the undifferentiated progenitor sheath followed by late-phase accrual of the bulbus arteriosus (BA). FGF inhibition during sheath migration reduced ventricle size and abolished BA formation, refining the window of FGF action during OFT formation. Our findings consolidate previous end-point analyses and establish zebrafish ventricle formation as a continuous process.

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Maternal hyperglycemia impedes second heart field-derived cardiomyocyte differentiation to elevate the risk of congenital heart defects

10.1101/2021.05.28.446177 ◽

2021 ◽

Author(s):

Sathiyanarayanan Manivannan ◽

Corrin Mansfield ◽

Xinmin Zhang ◽

Karthik M. Kodigepalli ◽

Uddalak Majumdar ◽

...

Keyword(s):

Congenital Heart ◽

Heart Defects ◽

Lineage Tracing ◽

Ventricular Wall ◽

Cardiomyocyte Differentiation ◽

Glucose Levels ◽

Second Heart Field ◽

Maternal Hyperglycemia ◽

Wall Thinning ◽

Heart Field

Congenital heart disease (CHD) is the most frequently occurring structural malformations of the heart affecting ~1% of live births. Besides genetic predisposition, embryonic exposure to teratogens during pregnancy increases the risk of CHD. However, the dose and cell-type-specific responses to an adverse maternal environment remain poorly defined. Here, we report a dose-response relationship between maternal glucose levels and phenotypic severity of CHD in offspring, using a chemically-induced pregestational diabetes mellitus (PGDM) mouse model. Embryos from dams with low-level maternal hyperglycemia (matHG) displayed trabeculation defects, ventricular wall thinning, and ventricular septal defects (VSD). On the other hand, embryos from dams with high-level matHG display outflow tract malformations, ventricular wall thinning and an increased rate of VSD. Our findings show that increasing levels of matHG exacerbates CHD occurrence and severity in offspring compared to control embryos. We applied single-cell RNA- sequencing to define matHG-related transcriptional differences in E9.5 and E11.5 hearts as comparing to controls. Disease-dependent gene-expression changes were observed in Isl1+ second heart field (SHF) and Tnnt2+ cardiomyocyte subpopulations. Lineage tracing studies in Isl1-Cre; RosamTmG embryonic hearts showed Isl1+-SHF-derived cardiomyocyte differentiation was impaired with matHG. This study highlights the influence of matHG-dosage on cardiac morphogenesis and identifies perturbations in the Isl1-dependent gene-regulatory network that affect SHF-derived cardiomyocyte differentiation contributing to matPGDM-induced CHD.

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Hox-dependent coordination of cardiac progenitor cell patterning and differentiation

10.1101/2020.01.23.916981 ◽

2020 ◽

Author(s):

Sonia Stefanovic ◽

Brigitte Laforest ◽

Jean-Pierre Desvignes ◽

Fabienne Lescroart ◽

Laurent Argiro ◽

...

Keyword(s):

Progenitor Cells ◽

Heart Defects ◽

Embryonic Stem ◽

Chromatin Accessibility ◽

Cardiac Differentiation ◽

Cardiac Progenitor Cells ◽

Heart Tube ◽

Atrioventricular Septal Defects ◽

Genome Wide ◽

Heart Field

SUMMARYPerturbation of addition of second heart field (SHF) cardiac progenitor cells to the poles of the heart tube results in congenital heart defects (CHD). The transcriptional programs and upstream regulatory events operating in different subpopulations of the SHF remain unclear. Here, we profile the transcriptome and chromatin accessibility of anterior and posterior SHF sub-populations at genome-wide levels and demonstrate that Hoxb1 negatively regulates differentiation in the posterior SHF. Spatial mis-expression of Hoxb1 in the anterior SHF results in hypoplastic right ventricle. Activation of Hoxb1 in embryonic stem cells arrests cardiac differentiation, whereas Hoxb1-deficient embryos display premature cardiac differentiation. Moreover, ectopic differentiation in the posterior SHF of embryos lacking both Hoxb1 and its paralog Hoxa1 results in atrioventricular septal defects. Our results show that Hoxb1 plays a key role in patterning cardiac progenitor cells that contribute to both cardiac poles and provide new insights into the pathogenesis of CHD.

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Delta-like ligand 4-mediated Notch signaling controls proliferation of second heart field progenitor cells by regulating Fgf8 expression

Development ◽

10.1242/dev.185249 ◽

2020 ◽

Vol 147 (17) ◽

pp. dev185249

Author(s):

Prashan De Zoysa ◽

Jiang Liu ◽

Omar Toubat ◽

Jongkyu Choi ◽

Anne Moon ◽

...

Keyword(s):

Right Ventricle ◽

Notch Signaling ◽

Cell Biology ◽

Ex Vivo ◽

Notch Pathway ◽

Double Outlet Right Ventricle ◽

Severe Form ◽

Second Heart Field ◽

Early Embryonic Lethality ◽

Heart Field

ABSTRACTThe role played by the Notch pathway in cardiac progenitor cell biology remains to be elucidated. Delta-like ligand 4 (Dll4), the arterial-specific Notch ligand, is expressed by second heart field (SHF) progenitors at time-points that are crucial in SHF biology. Dll4-mediated Notch signaling is required for maintaining an adequate pool of SHF progenitors, such that Dll4 knockout results in a reduction in proliferation and an increase in apoptosis. A reduced SHF progenitor pool leads to an underdeveloped right ventricle (RV) and outflow tract (OFT). In its most severe form, there is severe RV hypoplasia and poorly developed OFT resulting in early embryonic lethality. In its milder form, the OFT is foreshortened and misaligned, resulting in a double outlet right ventricle. Dll4-mediated Notch signaling maintains Fgf8 expression by transcriptional regulation at the promoter level. Combined heterozygous knockout of Dll4 and Fgf8 demonstrates genetic synergy in OFT alignment. Exogenous supplemental Fgf8 rescues proliferation in Dll4 mutants in ex-vivo culture. Our results establish a novel role for Dll4-mediated Notch signaling in SHF biology. More broadly, our model provides a platform for understanding oligogenic inheritance that results in clinically relevant OFT malformations.

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