Prenatal ethanol exposure impairs the conduction delay at the atrioventricular junction in the looping heart

2021 ◽  
Author(s):  
Shan Ling ◽  
Michael W Jenkins ◽  
Michiko Watanabe ◽  
Stephanie M Ford ◽  
Andrew M Rollins
Keyword(s):  
Heart Development ◽  
Molecular Mechanisms ◽  
Early Stage ◽  
Heart Defects ◽  
Ethanol Exposure ◽  
Cardiac Conduction ◽  
Conduction Delay ◽  
Prenatal Ethanol Exposure ◽  
Endocardial Cushions ◽  
Atrioventricular Junction

The etiology of ethanol-related congenital heart defects has been the focus of much study, but most research has concentrated on cellular and molecular mechanisms. We have shown with optical coherence tomography (OCT) that ethanol exposure led to increased retrograde flow and smaller atrioventricular (AV) cushions compared to controls. Since AV cushions play a role in patterning the conduction delay at the atrioventricular junction (AVJ), this study aims to investigate whether ethanol exposure alters the AVJ conduction in early looping hearts and whether this alteration is related to the decreased cushion size. Quail embryos were exposed to a single dose of ethanol at gastrulation, and Hamburger-Hamilton stage 19 - 20 hearts were dissected for imaging. Cardiac conduction was measured using an optical mapping microscope and we imaged the endocardial cushions using OCT. Our results showed that, compared with controls, ethanol-exposed embryos exhibited abnormally fast AVJ conduction and reduced cushion size. However, this increased conduction velocity (CV) did not strictly correlate with decreased cushion volume and thickness. By matching the CV map to the cushion size map, we found that the slowest conduction location was consistently at the atrial side of the AVJ, which had the thinner cushions, not at the thickest cushion location at the ventricular side as expected. Our findings reveal regional differences in the AVJ myocardium even at this early stage in heart development. These findings reveal the early steps leading to the heterogeneity and complexity of conduction at the mature AVJ, a site where arrhythmias can be initiated.

Folic acid prevents functional and structural heart defects induced by prenatal ethanol exposure

2021 ◽  
Author(s):  
Stephanie M Ford ◽  
Cameron J Pedersen ◽  
Matthew R Ford ◽  
Jun W Kim ◽  
Ganga H Karunamuni ◽  
...  
Keyword(s):  
Blood Flow ◽  
Folic Acid ◽  
Heart Diseases ◽  
Prenatal Alcohol Exposure ◽  
Heart Defects ◽  
Alcohol Exposure ◽  
Ethanol Exposure ◽  
Endocardial Cushion ◽  
Prenatal Ethanol Exposure ◽  
Endocardial Cushions

Increased regurgitant blood flow has been linked to endocardial cushion defects and resultant congenital heart diseases (CHDs). Prenatal alcohol exposure (PAE) has been shown to alter early blood flow resulting in abnormal endocardial cushions and CHDs. Compounds, including folic acid (FA), mitigate PAE effects and prevent CHDs, but few studies have assessed their effects on blood flow. We modeled binge drinking in quail embryos at gastrulation. Embryos were exposed to ethanol alone, FA (3.2 μg/egg) alone, and the two simultaneously. We quantified in cardiac looping stages (equivalent to 4 weeks of human gestation) regurgitant blood flow with Doppler optical coherence tomography (OCT) and endocardial cushion volumes using OCT imaging. Incidences of abnormal body curvature and heart rates were also measured. Embryos exposed to ethanol showed significantly increased regurgitant blood flow compared to controls, while embryos given FA with ethanol had significantly reduced regurgitant blood flow but did not return to control levels. Ethanol exposure led to significantly smaller, abnormal endocardial cushions and the addition of FA improved their size, but they remained smaller than controls. Abnormal body curvatures after PAE were reduced in incidence but not fully prevented by FA. FA supplementation partially alleviated PAE induced abnormal cardiovascular function and morphology. Normal blood flow and endocardial cushions are both required to produce a healthy four-chambered heart. These findings support that FA supplementation should begin early in pregnancy to prevent heart as well as neural tube defects. Investigations into the efficacy of combinations of compounds to prevent PAE-induced defects is warranted.

Reversal of cardiomyopathy resulting from prenatal exposure to ethanol

1984 ◽  
Vol 42 ◽  
pp. 716-717
Author(s):  
C. Uphoff ◽  
C. Nyquist-Battie
Keyword(s):  
Prenatal Exposure ◽  
Heart Development ◽  
Membrane Integrity ◽  
Ethanol Exposure ◽  
Prenatal Ethanol Exposure ◽  
Pathological Changes ◽  
Prenatally Exposed ◽  
Inner Mitochondrial Membrane ◽  
Fetal Alcohol ◽  
Newborn Mice

Fetal Alcohol Syndrone (FAS) is a syndrome with characteristic abnormalities resulting from prenatal exposure to ethanol. In many children with FAS syndrome gross pathological changes in the heart are seen with septal defects the most prevalent abnormality recorded. Few studies in animal models have been performed on the effects of ethanol on heart development. In our laboratory, it has been observed that prenatal ethanol exposure of Swiss albino mice results in abnormal cardiac muscle ultrastructure when mice were examined at birth and compared to pairfed and normal controls. Fig. 1 is an example of the changes that are seen in the ethanol-exposed animals. These changes include enlarged mitochondria with loss of inner mitochondrial membrane integrity and loss of myofibrils. Morphometric analysis substantiated the presence of these alterations from normal cardiac ultrastructure. The present work was undertaken to determine if the pathological changes seen in the newborn mice prenatally exposed to ethanol could be reversed with age and abstinence.

scholarly journals Semaphorin3f as an intrinsic regulator of chamber-specific heart development

2021 ◽  
Author(s):  
Rami Halabi ◽  
Paula B. Cechmanek ◽  
Carrie L. Hehr ◽  
Sarah McFarlane
Keyword(s):  
Congenital Heart Defects ◽  
Heart Development ◽  
Congenital Heart ◽  
Molecular Mechanisms ◽  
Heart Defects ◽  
Border Region ◽  
Specific Gene ◽  
Atrioventricular Canal ◽  
Term Survival ◽  
Ventricular Cardiomyocytes

During development a pool of precursors form a heart with atrial and ventricular chambers that exhibit distinct transcriptional and electrophysiological properties. Normal development of these chambers is essential for full term survival of the fetus, and deviations result in congenital heart defects. The large number of genes that may cause congenital heart defects when mutated, and the genetic variability and penetrance of the ensuing phenotypes, reveals a need to understand the molecular mechanisms that allow for the formation of chamber-specific cardiomyocyte differentiation. We find that in the developing zebrafish heart, mRNA for a secreted Semaphorin (Sema), Sema3fb, is expressed by all cardiomyocytes, whereas mRNA for its receptor Plexina3 (Plxna3) is expressed by ventricular cardiomyocytes. In sema3fb CRISPR zebrafish mutants, ventricular chamber development is impaired; the ventricles of mutants are smaller in size than their wild type siblings, apparently because of differences in cell size and not cell numbers, with ventricular cardiomyocytes failing to undergo normal developmental hypertrophy. Analysis of chamber differentiation indicates defects in chamber specific gene expression at the border between the ventricular and atrial chambers, with spillage of ventricular chamber genes into the atrium, and vice versa, and a failure to restrict bmp4a mRNA to the atrioventricular canal. The disrupted atrioventricular border region in mutants is accompanied by hypoplastic heart chambers and impaired cardiac function. These data suggest a model whereby cardiomyocytes secrete a Sema cue that, through spatially restricted expression of the receptor, signals in a ventricular chamber-specific manner to establish a distinct border between atrial and ventricular chambers that is important for functional development of the heart.

scholarly journals Electrophysiological phenotyping in genetically engineered mice

2003 ◽  
Vol 13 (3) ◽  
pp. 207-216 ◽  
Author(s):  
Charles I. Berul
Keyword(s):  
Molecular Mechanisms ◽  
Heart Defects ◽  
Gene Mutations ◽  
Genetically Engineered ◽  
Experimental Methodology ◽  
Cardiac Conduction ◽  
Disease States ◽  
Genetically Engineered Mice ◽  
Study Techniques

Advances in transgene and gene targeting technology have enabled sophisticated manipulation of the mouse genome, providing important insights into the molecular mechanisms underlying cardiac conduction, arrhythmogenesis, and sudden cardiac death. The mouse is currently the principal mammalian model for studying biological processes, particularly related to cardiac pathophysiology. Murine models have been engineered harboring gene mutations leading to inherited structural and electrical disorders of the heart due to transcription factor mutations, connexin protein defects, and G protein and ion channelopathies. These mutations lead to phenotypes reminiscent of human clinical disease states including congenital heart defects, cardiomyopathies, and long-QT syndrome, creating models of human electrophysiological disease. Functional analyses of the underlying molecular mechanisms of resultant phenotypes require appropriate and sophisticated experimental methodology. This paper reviews current in vivo murine electrophysiology study techniques and genetic mouse models pertinent to human arrhythmia disorders.

scholarly journals Neddylation mediates ventricular chamber maturation through repression of Hippo signaling

2018 ◽  
Vol 115 (17) ◽  
pp. E4101-E4110 ◽  
Author(s):  
Jianqiu Zou ◽  
Wenxia Ma ◽  
Jie Li ◽  
Rodney Littlejohn ◽  
Hongyi Zhou ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Development ◽  
Molecular Mechanisms ◽  
Heart Defects ◽  
Left Ventricular ◽  
Late Gestation ◽  
Hippo Signaling ◽  
Cardiomyocyte Proliferation ◽  
Ventricular Noncompaction ◽  
Cullin 7

During development, ventricular chamber maturation is a crucial step in the formation of a functionally competent postnatal heart. Defects in this process can lead to left ventricular noncompaction cardiomyopathy and heart failure. However, molecular mechanisms underlying ventricular chamber development remain incompletely understood. Neddylation is a posttranslational modification that attaches ubiquitin-like protein NEDD8 to protein targets via NEDD8-specific E1-E2-E3 enzymes. Here, we report that neddylation is temporally regulated in the heart and plays a key role in cardiac development. Cardiomyocyte-specific knockout of NAE1, a subunit of the E1 neddylation activating enzyme, significantly decreased neddylated proteins in the heart. Mice lacking NAE1 developed myocardial hypoplasia, ventricular noncompaction, and heart failure at late gestation, which led to perinatal lethality. NAE1 deletion resulted in dysregulation of cell cycle-regulatory genes and blockade of cardiomyocyte proliferation in vivo and in vitro, which was accompanied by the accumulation of the Hippo kinases Mst1 and LATS1/2 and the inactivation of the YAP pathway. Furthermore, reactivation of YAP signaling in NAE1-inactivated cardiomyocytes restored cell proliferation, and YAP-deficient hearts displayed a noncompaction phenotype, supporting an important role of Hippo-YAP signaling in NAE1-depleted hearts. Mechanistically, we found that neddylation regulates Mst1 and LATS2 degradation and that Cullin 7, a NEDD8 substrate, acts as the ubiquitin ligase of Mst1 to enable YAP signaling and cardiomyocyte proliferation. Together, these findings demonstrate a role for neddylation in heart development and, more specifically, in the maturation of ventricular chambers and also identify the NEDD8 substrate Cullin 7 as a regulator of Hippo-YAP signaling.

A novel role for VEGF in endocardial cushion formation and its potential contribution to congenital heart defects

Development ◽  
2001 ◽  
Vol 128 (9) ◽  
pp. 1531-1538 ◽  
Author(s):  
Y. Dor ◽  
T.D. Camenisch ◽  
A. Itin ◽  
G.I. Fishman ◽  
J.A. McDonald ◽  
...  
Keyword(s):  
Growth Factor ◽  
Heart Development ◽  
Heart Defects ◽  
Negative Regulator ◽  
Congenital Defects ◽  
Endocardial Cushion ◽  
Potential Contribution ◽  
Vegf Receptor ◽  
Endocardial Cushions ◽  
Mesenchymal Transformation

Normal cardiovascular development is exquisitely dependent on the correct dosage of the angiogenic growth factor and vascular morphogen vascular endothelial growth factor (VEGF). However, cardiac expression of VEGF is also robustly augmented during hypoxic insults, potentially mediating the well-established teratogenic effects of hypoxia on heart development. We report that during normal heart morphogenesis VEGF is specifically upregulated in the atrioventricular (AV) field of the heart tube soon after the onset of endocardial cushion formation (i.e. the endocardium-derived structures that build the heart septa and valves). To model hypoxia-dependent induction of VEGF in vivo, we conditionally induced VEGF expression in the myocardium using a tetracycline-regulated transgenic system. Premature induction of myocardial VEGF in E9.5 embryos to levels comparable with those induced by hypoxia prevented formation of endocardial cushions. When added to explanted embryonic AV tissue, VEGF fully inhibited endocardial-to-mesenchymal transformation. Transformation was also abrogated in AV explants subjected to experimental hypoxia but fully restored in the presence of an inhibitory soluble VEGF receptor 1 chimeric protein. Together, these results suggest a novel developmental role for VEGF as a negative regulator of endocardial-to-mesenchymal transformation that underlies the formation of endocardial cushions. Moreover, ischemia-induced VEGF may be the molecular link between hypoxia and congenital defects in heart septation.

scholarly journals From Stem Cells to Populations—Using hiPSC, Next-Generation Sequencing, and GWAS to Explore the Genetic and Molecular Mechanisms of Congenital Heart Defects

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 921
Author(s):  
Martin Broberg ◽  
Johanna Hästbacka ◽  
Emmi Helle
Keyword(s):  
Stem Cells ◽  
Congenital Heart Defects ◽  
Heart Development ◽  
Congenital Heart ◽  
Molecular Mechanisms ◽  
Association Studies ◽  
Heart Defects ◽  
Cell Types ◽  
Mendelian Inheritance ◽  
Genome Wide Association Studies

Congenital heart defects (CHD) are developmental malformations affecting the heart and the great vessels. Early heart development requires temporally regulated crosstalk between multiple cell types, signaling pathways, and mechanical forces of early blood flow. While both genetic and environmental factors have been recognized to be involved, identifying causal genes in non-syndromic CHD has been difficult. While variants following Mendelian inheritance have been identified by linkage analysis in a few families with multiple affected members, the inheritance pattern in most familial cases is complex, with reduced penetrance and variable expressivity. Furthermore, most non-syndromic CHD are sporadic. Improved sequencing technologies and large biobank collections have enabled genome-wide association studies (GWAS) in non-syndromic CHD. The ability to generate human to create human induced pluripotent stem cells (hiPSC) and further differentiate them to organotypic cells enables further exploration of genotype–phenotype correlations in patient-derived cells. Here we review how these technologies can be used in unraveling the genetics and molecular mechanisms of heart development.

scholarly journals Role of the Epicardium in the Development of the Atrioventricular Valves and Its Relevance to the Pathogenesis of Myxomatous Valve Disease

2021 ◽  
Vol 8 (5) ◽  
pp. 54
Author(s):  
Renélyn Wolters ◽  
Ray Deepe ◽  
Jenna Drummond ◽  
Andrew B. Harvey ◽  
Emilye Hiriart ◽  
...  
Keyword(s):  
Heart Development ◽  
Molecular Mechanisms ◽  
Valve Disease ◽  
Developmental Defects ◽  
Atrioventricular Valves ◽  
Atrioventricular Junction ◽  
Left Behind ◽  
Cardiovascular Biology ◽  
Valve Formation

This paper is dedicated to the memory of Dr. Adriana “Adri” Gittenberger-de Groot and in appreciation of her work in the field of developmental cardiovascular biology and the legacy that she has left behind. During her impressive career, Dr. Gittenberger-de Groot studied many aspects of heart development, including aspects of cardiac valve formation and disease and the role of the epicardium in the formation of the heart. In this contribution, we review some of the work on the role of epicardially-derived cells (EPDCs) in the development of the atrioventricular valves and their potential involvement in the pathogenesis of myxomatous valve disease (MVD). We provide an overview of critical events in the development of the atrioventricular junction, discuss the role of the epicardium in these events, and illustrate how interfering with molecular mechanisms that are involved in the epicardial-dependent formation of the atrioventricular junction leads to a number of abnormalities. These abnormalities include defects of the AV valves that resemble those observed in humans that suffer from MVD. The studies demonstrate the importance of the epicardium for the proper formation and maturation of the AV valves and show that the possibility of epicardial-associated developmental defects should be taken into consideration when determining the genetic origin and pathogenesis of MVD.

scholarly journals Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects?

2014 ◽  
Vol 306 (3) ◽  
pp. H414-H421 ◽  
Author(s):  
Ganga Karunamuni ◽  
Shi Gu ◽  
Yong Qiu Doughman ◽  
Lindsy M. Peterson ◽  
Katherine Mai ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Congenital Heart Defects ◽  
Late Stage ◽  
Congenital Heart ◽  
Molecular Mechanisms ◽  
Imaging Modality ◽  
Heart Defects ◽  
Ethanol Exposure ◽  
The Body ◽  
Life Threatening

Alcohol-induced congenital heart defects are frequently among the most life threatening and require surgical correction in newborns. The etiology of these defects, collectively known as fetal alcohol syndrome, has been the focus of much study, particularly involving cellular and molecular mechanisms. Few studies have addressed the influential role of altered cardiac function in early embryogenesis because of a lack of tools with the capability to assay tiny beating hearts. To overcome this gap in our understanding, we used optical coherence tomography (OCT), a nondestructive imaging modality capable of micrometer-scale resolution imaging, to rapidly and accurately map cardiovascular structure and hemodynamics in real time under physiological conditions. In this study, we exposed avian embryos to a single dose of alcohol/ethanol at gastrulation when the embryo is sensitive to the induction of birth defects. Late-stage hearts were analyzed using standard histological analysis with a focus on the atrio-ventricular valves. Early cardiac function was assayed using Doppler OCT, and structural analysis of the cardiac cushions was performed using OCT imaging. Our results indicated that ethanol-exposed embryos developed late-stage valvuloseptal defects. At early stages, they exhibited increased regurgitant flow and developed smaller atrio-ventricular cardiac cushions, compared with controls (uninjected and saline-injected embryos). The embryos also exhibited abnormal flexion/torsion of the body. Our evidence suggests that ethanol-induced alterations in early cardiac function have the potential to contribute to late-stage valve and septal defects, thus demonstrating that functional parameters may serve as early and sensitive gauges of cardiac normalcy and abnormalities.

scholarly journals Atrial and Sinoatrial Node Development in the Zebrafish Heart

2021 ◽  
Vol 8 (2) ◽  
pp. 15
Author(s):  
Kendall E. Martin ◽  
Joshua S. Waxman
Keyword(s):  
Heart Development ◽  
Molecular Mechanisms ◽  
Sinoatrial Node ◽  
Genetic Manipulation ◽  
Heart Defects ◽  
Postnatal Life ◽  
And Function ◽  
Early Developmental ◽  
Node Development ◽  
Chamber Size

Proper development and function of the vertebrate heart is vital for embryonic and postnatal life. Many congenital heart defects in humans are associated with disruption of genes that direct the formation or maintenance of atrial and pacemaker cardiomyocytes at the venous pole of the heart. Zebrafish are an outstanding model for studying vertebrate cardiogenesis, due to the conservation of molecular mechanisms underlying early heart development, external development, and ease of genetic manipulation. Here, we discuss early developmental mechanisms that instruct appropriate formation of the venous pole in zebrafish embryos. We primarily focus on signals that determine atrial chamber size and the specialized pacemaker cells of the sinoatrial node through directing proper specification and differentiation, as well as contemporary insights into the plasticity and maintenance of cardiomyocyte identity in embryonic zebrafish hearts. Finally, we integrate how these insights into zebrafish cardiogenesis can serve as models for human atrial defects and arrhythmias.

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