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

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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Lamb1a regulates atrial growth by limiting second heart field addition during zebrafish heart development

Development ◽

10.1242/dev.199691 ◽

2021 ◽

Author(s):

Christopher J. Derrick ◽

Eric J. G. Pollitt ◽

Ashley Sanchez Sevilla Uruchurtu ◽

Farah Hussein ◽

Andrew J. Grierson ◽

...

Keyword(s):

Heart Development ◽

Cardiac Development ◽

Cardiac Contractility ◽

Asymmetric Structure ◽

Specific Expression ◽

Heart Morphogenesis ◽

Second Heart Field ◽

Heart Field ◽

Heart Size ◽

Zebrafish Heart

During early vertebrate heart development the heart transitions from a linear tube to a complex asymmetric structure, a morphogenetic process which occurs simultaneously with growth of the heart. Cardiac growth during early heart morphogenesis is driven by deployment of cells from the Second Heart Field (SHF) into both poles of the heart. Laminin is a core component of the extracellular matrix (ECM), and although mutations in laminin subunits are linked with cardiac abnormalities, no role for laminin has been identified in early vertebrate heart morphogenesis. We identified tissue-specific expression of laminin genes in the developing zebrafish heart, supporting a role for laminins in heart morphogenesis. Analysis of heart development in lamb1a zebrafish mutant embryos reveals mild morphogenetic defects and progressive cardiomegaly, and that Lamb1a functions to limit heart size during cardiac development by restricting SHF addition. lamb1a mutants exhibit hallmarks of altered haemodynamics, and blocking cardiac contractility in lamb1a mutants rescues heart size and atrial SHF addition. Together this suggests that laminin mediates interactions between SHF deployment and cardiac biomechanics during heart development and growth in the developing embryo.

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A Role for the Cytoskeleton in Heart Looping

The Scientific World JOURNAL ◽

10.1100/tsw.2007.87 ◽

2007 ◽

Vol 7 ◽

pp. 280-298 ◽

Cited By ~ 23

Author(s):

Kersti K. Linask ◽

Michael VanAuker

Keyword(s):

Heart Development ◽

Cell Biology ◽

Heart Defects ◽

Heart Tube ◽

Second Heart Field ◽

The Past ◽

Complex Process ◽

Nonmuscle Myosin Ii ◽

Heart Looping ◽

Heart Field

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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Abstract MP245: Tet Proteins Regulate Second Heart Field Multipotent Progenitors Differentiating To Myocytes

Circulation Research ◽

10.1161/res.129.suppl_1.mp245 ◽

2021 ◽

Vol 129 (Suppl_1) ◽

Author(s):

Shaohai Fang ◽

Jia Li ◽

Jeff D Steimle ◽

Lei Guo ◽

Yuhan Yang ◽

...

Keyword(s):

Dna Methylation ◽

Heart Development ◽

Cardiac Development ◽

Critical Role ◽

Dna Demethylation ◽

Lineage Specification ◽

Second Heart Field ◽

Heart Field ◽

Cardiac Lineage ◽

Tet Protein

DNA methylation and demethylation play an important role in shaping the epigenetic landscape and chromatin accessibility to control gene expression during development in mammals. Ten-eleven Translocation (Tet1, Tet2 and Tet3) is a family of dioxygenases that catalyze DNA methylation oxidation with ultimate DNA demethylation. Our previous study showed that cardiac-specific deletion of Tet2 and Tet3 could disrupt YY1-mediated long range chromatin interactions during heart development and lead to ventricular non-compaction cardiomyopathy. However, it is still unclear whether and how Tet protein mediated epigenetic modifications contribute to cardiac lineage specification during embryonic development. In this study, we generated cardiac specific Tet1-3 triple deficient (Tet-TKO) mouse lines using various cardiac specific Cres to evaluate the function of Tet protein in regulating cardiac lineage specification. We observed developmental defects at outflow tract (OFT) in Tet-TKO embryos, suggesting that Tet deficiency affects the second heart field (SHF) development. Single cell RNA-seq analysis further revealed the accumulation of multipotent SHF progenitors and subsequent halt of myocyte differentiation upon Tet depletion. At the molecular level, we found that Tet ablation perturbs the transcriptional network of Islet1, a transcription factor that is crucial for cardiac development in embryos. Overall, our study demonstrates a critical role of Tet-mediated epigenetic regulation for embryonic cardiac development.

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Overexpression of the tinman-related genes XNkx-2.5 and XNkx-2.3 in Xenopus embryos results in myocardial hyperplasia

Development ◽

10.1242/dev.122.11.3549 ◽

1996 ◽

Vol 122 (11) ◽

pp. 3549-3556 ◽

Cited By ~ 18

Author(s):

O.B. Cleaver ◽

K.D. Patterson ◽

P.A. Krieg

Keyword(s):

Heart Development ◽

Homeobox Gene ◽

Cardiac Differentiation ◽

Myocardial Cells ◽

Differentiation Markers ◽

Heart Field ◽

Cardiac Mesoderm ◽

Xenopus Laevis Embryos ◽

Functional Homologues

Drosophila tinman is an NK-class homeobox gene required for formation of the dorsal vessel, the insect equivalent of the vertebrate heart. Vertebrate sequences related to tinman, such as mouse Nkx-2.5, chicken cNkx-2.5, Xenopus XNkx-2.5 and XNkx-2.3 are expressed in cardiac precursors and in tissues involved in induction of cardiac mesoderm. Mice which lack a functional Nkx-2.5 gene die due to cardiac defects. To determine the role of tinman-related sequences in heart development, we have overexpressed both XNkx-2.3 and XNkx-2.5 in Xenopus laevis embryos. The resulting embryos are morphologically normal except that they have enlarged hearts. The enlarged heart phenotype is due to a thickening of the myocardium caused by an increase in the overall number of myocardial cells (hyperplasia). Neither ectopic nor precocious expression of cardiac differentiation markers is detectable in overexpressing embryos. These results suggest that both XNkx-2.3 and XNkx-2.5 are functional homologues of tinman, responsible for maintenance of the heart field.

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Smyd1 Orchestrates Early Heart Development Through Positive and Negative Gene Regulation

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.654682 ◽

2021 ◽

Vol 9 ◽

Author(s):

Zhen Wang ◽

Robert J. Schwartz ◽

Jing Liu ◽

Fei Sun ◽

Qi Li ◽

...

Keyword(s):

Heart Development ◽

Striated Muscle ◽

Trichostatin A ◽

Structural Defects ◽

Reporter System ◽

Cardiac Phenotype ◽

Deacetylase Inhibitor ◽

Heart Field ◽

Polymerase Chain ◽

Negative Gene

SET and MYND domain-containing protein 1 (Smyd1) is a striated muscle-specific histone methyltransferase. Our previous work demonstrated that deletion of Smyd1 in either cardiomyocytes or the outflow tract (OFT) resulted in embryonic lethality at E9.5, with cardiac structural defects such as truncation of the OFT and right ventricle and impaired expansion and proliferation of the second heart field (SHF). The cardiac phenotype was accompanied by the downregulation of ISL LIM Homeobox 1 (Isl1) and upregulation of atrial natriuretic factor (ANF). However, the mechanisms of Smyd1 regulating Isl1 and ANF during embryonic heart development remain to be elucidated. Here, we employed various biochemical and molecular biological approaches including chromatin immunoprecipitation polymerase chain reaction (ChIP-PCR), pGL3 fluorescence reporter system, and co-immunoprecipitation (CoIP) and found that Smyd1 interacted with absent small homeotic-2-like protein (ASH2L) and activated the promoter of Isl1 by trimethylating H3K4. We also found that Smyd1 associated with HDAC to repress ANF expression using trichostatin A (TSA), a deacetylase inhibitor. In conclusion, Smyd1 participates in early heart development by upregulating the expression of Isl1 and downregulating the expression of ANF.

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Expression of the BMP Receptor Alk3 in the Second Heart Field Is Essential for Development of the Dorsal Mesenchymal Protrusion and Atrioventricular Septation

Circulation Research ◽

10.1161/circresaha.112.300821 ◽

2013 ◽

Vol 112 (11) ◽

pp. 1420-1432 ◽

Cited By ~ 48

Author(s):

Laura E. Briggs ◽

Aimee L. Phelps ◽

Elizabeth Brown ◽

Jayant Kakarla ◽

Robert H. Anderson ◽

...

Keyword(s):

Second Heart Field ◽

Bmp Receptor ◽

Heart Field ◽

Dorsal Mesenchymal Protrusion ◽

Atrioventricular Septation

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Loss of Wnt5a disrupts second heart field cell deployment and may contribute to OFT malformations in DiGeorge syndrome

Human Molecular Genetics ◽

10.1093/hmg/ddu584 ◽

2014 ◽

Vol 24 (6) ◽

pp. 1704-1716 ◽

Cited By ~ 32

Author(s):

Tanvi Sinha ◽

Ding Li ◽

Magali Théveniau-Ruissy ◽

Mary R. Hutson ◽

Robert G. Kelly ◽

...

Keyword(s):

Digeorge Syndrome ◽

Second Heart Field ◽

Heart Field

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A Boolean Model of the Cardiac Gene Regulatory Network Determining First and Second Heart Field Identity

PLoS ONE ◽

10.1371/journal.pone.0046798 ◽

2012 ◽

Vol 7 (10) ◽

pp. e46798 ◽

Cited By ~ 36

Author(s):

Franziska Herrmann ◽

Alexander Groß ◽

Dao Zhou ◽

Hans A. Kestler ◽

Michael Kühl

Keyword(s):

Gene Regulatory Network ◽

Regulatory Network ◽

Boolean Model ◽

Second Heart Field ◽

Cardiac Gene ◽

Heart Field ◽

Gene Regulatory

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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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