scholarly journals Gpr126 domains control different cellular mechanisms of ventricular chamber development

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
S Srivastava ◽  
F Gunanwan ◽  
S Guenther ◽  
F Ferrazzi ◽  
A Gentile ◽  
...  
Keyword(s):  
Heart Development ◽  
Molecular Mechanisms ◽  
Heart Defects ◽  
Left Ventricular ◽  
Cell Junctions ◽  
Cellular Mechanisms ◽  
Form Complex ◽  
Terminal Fragment ◽  
Erbb2 Signaling ◽  
Cell Cell

Abstract Introduction Trabeculation is a crucial process during ventricular chamber development which describes the protrusion of cardiomyocytes into the lumen of the ventricular chamber to form complex muscular structures called trabeculae. Defects in this process results in various human diseases such as left ventricular non compaction cardiomyopathies and other congenital heart defects. Several cellular mechanisms have been identified underlying trabeculation including tension heterogeneity induced cardiomyocyte selection, depolarization and delamination. However, the molecular mechanisms governing trabeculation are still poorly understood. Purpose Previously, we have shown that Gpr126 is required for trabeculation and heart development in mice and zebrafish. Gpr126 is an adhesion G-protein coupled receptor which is autoproteolytically cleaved into an N-terminal fragment (NTF) and a C-terminal fragment (CTF). Here, we show that NTF and CTF control different cellular processes during trabeculation. Methods and results In-vivo confocal images of hearts of CTF-depleted mutants gpr126st49 (expressing NTF) revealed a multilayered ventricular wall lacking any trabecular projections, which is in contrast to our previous results obtained with morpholinos suggesting that the NTF is sufficient for proper heart development in zebrafish. A molecular characterization of gpr126st49 mutants showed that cardiomyocytes in the multilayer fail to depolarize and relocalize N-cadherin from the lateral to the basal side, indicating that the cardiomyocytes in the multi-layered wall fail to attain a trabecular identity. In addition, these mutants showed significantly upregulated myocardial notch expression, which is known to prevent cardiomyocytes from attaining a trabecular identity. These data suggest that CTF is required for proper formation of trabeculae. We analyzed the full length-depleted mutant gpr126stl47 for trabeculation defects and observed that 17% of gpr126stl47 maternal zygotic mutants exhibited complete absence of trabeculation and 27% hypotrabeculation. Analysis of these mutants revealed that instead of being specifically localized at the junctions, N-cadherin was mainly distributed to the apical and basal side in the compact layer cardiomyocytes. This indicates that the NTF is required for maintaining the cell-cell adhesion in the compact wall. Finally, overexpression of gpr126 in the absence of Erbb2 signaling and blood flow / -or contractility failed to cause multilayering suggesting that Gpr126 is part of the well-established Erbb2 signaling cascade controlling trabeculation. Conclusion Collectively, our data support a model with domain-specific functions of Gpr126 in ventricular chamber development, where the NTF of Gpr126 is required for maintaining the compact wall integrity at the onset of trabeculation by maintaining cell-cell junctions, while the CTF helps in providing trabecular identity to cardiomyocytes through modulation of myocardial notch activity. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): DFG

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.

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.

scholarly journals Cardiovascular phenotyping of the first mouse model of Sarcoidosis

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
C Bueno Beti ◽  
C Lim ◽  
A Protonotarios ◽  
A Kiss ◽  
M.N Sheppard ◽  
...  
Keyword(s):  
Mouse Model ◽  
Molecular Mechanisms ◽  
Left Ventricular ◽  
Cell Junctions ◽  
Left Ventricular Ejection ◽  
Unknown Etiology ◽  
Funding Source ◽  
Ventricular Ejection Fraction ◽  
Arrhythmogenic Substrate ◽  
Inflammatory Infiltrates

Abstract Introduction Sarcoidosis is a potentially life-threatening, inflammatory, granulomatous disease that affects multiple organs including the heart. Heretofore, its unknown etiology had hindered the creation of experimental models and the understanding of the molecular mechanisms of pathogenesis behind it. Purpose To extensively phenotype the heart of the first mouse model of sarcoidosis created through deletion of the tuberous sclerosis 2 (Tsc2) gene in the CD11c-positive macrophage population. Methods Tsc2 fl/fl CD11c Cre+ (Tsc2-KO; n=7) and Tsc2 fl/fl CD11c Cre- (Tsc2-WT; n=7) mice were subjected to echocardiography at 25 weeks of age (woa) to assess myocardial dimensions and function. Hearts of 13 and 25woa animals were subjected to histological and immunological stains to assess tissue changes, subtype inflammatory infiltrates and examine the localization of key proteins shown to be re-distributed in patients. Results At 13 woa, Tsc2-KO animals show inflammatory infiltrates; subtyped mainly as macrophages as well as evidence of myocyte destruction. At 25 woa, the number of inflammatory cells is significantly higher and there is heavy fibrotic replacement primarily in the septum and trabeculae. Older animals also show giant cells and non-necrotizing granulomas. The hearts show heterogeneous gap junction remodeling known to constitute an arrhythmogenic substrate and lack of immunoreactive signal for the desmosomal protein plakoglobin from the cell-cell junctions just as described in patients. The left ventricular ejection fraction and LV morphology was not significantly different between the two groups (EF: 64±4% in Tsc2-KO vs 64±2% in Tsc2-WT; LV end-systolic diameter: 4.51±0.54 mm in Tsc2-KO vs 4.59±0.29 mm in Tsc2-WT). However, there was a strong trend towards increasing filling pressure (E/e'ratio; 14.24±4.01 vs 12.15±2.54) and mean pulmonary pressure (21±6 vs 18±3 mmHg) in Tsc2-KO mice compared to controls suggesting diastolic dysfunction. Conclusion Hearts of the Tsc2 fl/fl CD11c Cre+ animals show a phenotype highly reminiscent of cardiac sarcoidosis in patients. We anticipate that this model will be very useful in deciphering molecular mechanisms of pathogenesis as well as testing much-needed mechanism-based therapies. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): British Heart Foundation - PG/18/27/33616

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 Molecular mechanisms of endothelial hyperpermeability: implications in inflammation

2009 ◽  
Vol 11 ◽  
Author(s):  
Puneet Kumar ◽  
Qiang Shen ◽  
Christopher D. Pivetti ◽  
Eugene S. Lee ◽  
Mack H. Wu ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Structural Changes ◽  
Molecular Mechanisms ◽  
Therapeutic Potential ◽  
Control Cell ◽  
Cell Junctions ◽  
Ischaemia Reperfusion Injury ◽  
Signalling Molecules ◽  
Endothelial Hyperpermeability ◽  
Cell Cell

Endothelial hyperpermeability is a significant problem in vascular inflammation associated with trauma, ischaemia–reperfusion injury, sepsis, adult respiratory distress syndrome, diabetes, thrombosis and cancer. An important mechanism underlying this process is increased paracellular leakage of plasma fluid and protein. Inflammatory stimuli such as histamine, thrombin, vascular endothelial growth factor and activated neutrophils can cause dissociation of cell–cell junctions between endothelial cells as well as cytoskeleton contraction, leading to a widened intercellular space that facilitates transendothelial flux. Such structural changes initiate with agonist–receptor binding, followed by activation of intracellular signalling molecules including calcium, protein kinase C, tyrosine kinases, myosin light chain kinase, and small Rho-GTPases; these kinases and GTPases then phosphorylate or alter the conformation of different subcellular components that control cell–cell adhesion, resulting in paracellular hypermeability. Targeting key signalling molecules that mediate endothelial-junction–cytoskeleton dissociation demonstrates a therapeutic potential to improve vascular barrier function during inflammatory injury.

scholarly journals Molecular mechanisms of cell–cell spread of intracellular bacterial pathogens

Open Biology ◽  
2013 ◽  
Vol 3 (7) ◽  
pp. 130079 ◽  
Author(s):  
Keith Ireton
Keyword(s):  
Actin Filaments ◽  
Molecular Mechanisms ◽  
Bacterial Pathogens ◽  
Shigella Flexneri ◽  
Cell Junctions ◽  
Adjacent Cell ◽  
Formation Mechanisms ◽  
Recent Developments ◽  
Host Plasma Membrane ◽  
Cell Cell

Several bacterial pathogens, including Listeria monocytogenes , Shigella flexneri and Rickettsia spp., have evolved mechanisms to actively spread within human tissues. Spreading is initiated by the pathogen-induced recruitment of host filamentous (F)-actin. F-actin forms a tail behind the microbe, propelling it through the cytoplasm. The motile pathogen then encounters the host plasma membrane, forming a bacterium-containing protrusion that is engulfed by an adjacent cell. Over the past two decades, much progress has been made in elucidating mechanisms of F-actin tail formation. Listeria and Shigella produce tails of branched actin filaments by subverting the host Arp2/3 complex. By contrast, Rickettsia forms tails with linear actin filaments through a bacterial mimic of eukaryotic formins. Compared with F-actin tail formation, mechanisms controlling bacterial protrusions are less well understood. However, recent findings have highlighted the importance of pathogen manipulation of host cell–cell junctions in spread. Listeria produces a soluble protein that enhances bacterial protrusions by perturbing tight junctions. Shigella protrusions are engulfed through a clathrin-mediated pathway at ‘tricellular junctions’—specialized membrane regions at the intersection of three epithelial cells. This review summarizes key past findings in pathogen spread, and focuses on recent developments in actin-based motility and the formation and internalization of bacterial protrusions.

A chimeric N-cadherin/beta 1-integrin receptor which localizes to both cell-cell and cell-matrix adhesions

1992 ◽  
Vol 103 (4) ◽  
pp. 943-951 ◽  
Author(s):  
B. Geiger ◽  
D. Salomon ◽  
M. Takeichi ◽  
R.O. Hynes
Keyword(s):  
Molecular Mechanisms ◽  
Cytoplasmic Domain ◽  
Cell Junctions ◽  
Integrin Receptor ◽  
Cell Contacts ◽  
Cell Matrix ◽  
Focal Contacts ◽  
Extracellular Region ◽  
Beta 1 Integrin ◽  
Cell Cell

To study the molecular mechanisms involved in formation of cell contacts, we have transfected cultured cells with a chimeric cDNA encoding the cytoplasmic and transmembrane domains of beta 1 integrin and the extracellular region of N-cadherin and determined the subcellular distribution of the chimeric molecule. We show that the chimeric receptor associates preferentially with cell-matrix focal contacts, suggesting that its distribution is directed by its beta 1 integrin segment, presumably via interactions of the cytoplasmic domain with cytoskeletal elements characteristic of focal contacts. Transfected cells which expressed relatively high levels of the cadherin/integrin chimera underwent an apparent epithelialization and contained the molecule both in cell-matrix and cell-cell contacts. Location in cell-cell contacts indicates competence of the cadherin extracellular domain to participate in formation of cell-cell junctions using a foreign cytoplasmic domain. Labeling of these cultures for talin, which is normally associated only with matrix adhesions, revealed specific labeling along the newly formed intercellular junctions. This suggests that the local association of talin with these sites is induced by the cytoplasmic tail of beta 1 integrin receptor presented by the chimeric protein. These results suggest that the formation of adherens-type junctions is driven by the cooperative interactions of the relevant adhesion molecules (cadherins and integrins) both with the respective extracellular ligands and with the cytoskeleton.

scholarly journals The F-BAR domain of SRGP-1 facilitates cell–cell adhesion during C. elegans morphogenesis

2010 ◽  
Vol 191 (4) ◽  
pp. 761-769 ◽  
Author(s):  
Ronen Zaidel-Bar ◽  
Michael J. Joyce ◽  
Allison M. Lynch ◽  
Kristen Witte ◽  
Anjon Audhya ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Molecular Mechanisms ◽  
Function Analysis ◽  
Membrane Dynamics ◽  
Protein Domain ◽  
Cell Junctions ◽  
Cell Junction ◽  
Loss Of Function ◽  
Bar Domain ◽  
Cell Cell

Robust cell–cell adhesion is critical for tissue integrity and morphogenesis, yet little is known about the molecular mechanisms controlling cell–cell junction architecture and strength. We discovered that SRGP-1 is a novel component of cell–cell junctions in Caenorhabditis elegans, localizing via its F-BAR (Bin1, Amphiphysin, and RVS167) domain and a flanking 200–amino acid sequence. SRGP-1 activity promotes an increase in membrane dynamics at nascent cell–cell contacts and the rapid formation of new junctions; in addition, srgp-1 loss of function is lethal in embryos with compromised cadherin–catenin complexes. Conversely, excess SRGP-1 activity leads to outward bending and projections of junctions. The C-terminal half of SRGP-1 interacts with the N-terminal F-BAR domain and negatively regulates its activity. Significantly, in vivo structure–function analysis establishes a role for the F-BAR domain in promoting rapid and robust cell adhesion during embryonic closure events, independent of the Rho guanosine triphosphatase–activating protein domain. These studies establish a new role for this conserved protein family in modulating cell–cell adhesion.

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 Lulu2 regulates the circumferential actomyosin tensile system in epithelial cells through p114RhoGEF

2011 ◽  
Vol 195 (2) ◽  
pp. 245-261 ◽  
Author(s):  
Hiroyuki Nakajima ◽  
Takuji Tanoue
Keyword(s):  
Epithelial Cells ◽  
Cell Shape ◽  
Molecular Mechanisms ◽  
Molecular System ◽  
Apical Cell ◽  
Cell Junctions ◽  
Cellular Processes ◽  
Kinase C ◽  
Important Regulator ◽  
Cell Cell

Myosin II–driven mechanical forces control epithelial cell shape and morphogenesis. In particular, the circumferential actomyosin belt, which is located along apical cell–cell junctions, regulates many cellular processes. Despite its importance, the molecular mechanisms regulating the belt are not fully understood. In this paper, we characterize Lulu2, a FERM (4.1 protein, ezrin, radixin, moesin) domain–containing molecule homologous to Drosophila melanogaster Yurt, as an important regulator. In epithelial cells, Lulu2 is localized along apical cell–cell boundaries, and Lulu2 depletion by ribonucleic acid interference results in disorganization of the circumferential actomyosin belt. In its regulation of the belt, Lulu2 interacts with and activates p114RhoGEF, a Rho-specific guanine nucleotide exchanging factor (GEF), at apical cell–cell junctions. This interaction is negatively regulated via phosphorylation events in the FERM-adjacent domain of Lulu2 catalyzed by atypical protein kinase C. We further found that Patj, an apical cell polarity regulator, recruits p114RhoGEF to apical cell–cell boundaries via PDZ (PSD-95/Dlg/ZO-1) domain–mediated interaction. These findings therefore reveal a novel molecular system regulating the circumferential actomyosin belt in epithelial cells.

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