Cardiac forces regulate zebrafish heart valve delamination by modulating Nfat signaling

In the clinic, most cases of congenital heart valve defects are thought to arise through errors that occur after the endothelial–mesenchymal transition (EndoMT) stage of valve development. Although mechanical forces caused by heartbeat are essential modulators of cardiovascular development, their role in these later developmental events is poorly understood. To address this question, we used the zebrafish superior atrioventricular valve (AV) as a model. We found that cellularized cushions of the superior atrioventricular canal (AVC) morph into valve leaflets via mesenchymal–endothelial transition (MEndoT) and tissue sheet delamination. Defects in delamination result in thickened, hyperplastic valves, and reduced heart function. Mechanical, chemical, and genetic perturbation of cardiac forces showed that mechanical stimuli are important regulators of valve delamination. Mechanistically, we show that forces modulate Nfatc activity to control delamination. Together, our results establish the cellular and molecular signature of cardiac valve delamination in vivo and demonstrate the continuous regulatory role of mechanical forces and blood flow during valve formation.

Precise Dose of Folic Acid Supplementation Is Essential for Embryonic Heart Development in Zebrafish

Folic acid, one of the 13 essential vitamins, plays an important role in cardiovascular development. Mutations in folic acid synthesis gene 5,10-methylenetetrahydrofolate reductase (MTHFR) is associated with the occurrence of congenital heart disease. However, the mechanisms underlying the regulation of cardiac development by mthfr gene are poorly understood. Here, we exposed zebrafish embryos to excessive folate or folate metabolism inhibitors. Moreover, we established a knock-out mutant of mthfr gene in zebrafish by using CRISPR/Cas9. The zebrafish embryos of insufficient or excessive folic acid and mthfr−/− mutant all gave rise to early pericardial edema and cardiac defect at 3 days post fertilization (dpf). Furthermore, the folic acid treated embryos showed abnormal movement at 5 dpf. The expression levels of cardiac marker genes hand2, gata4, and nppa changed in the abnormality of folate metabolism embryos and mthfr−/− mutant, and there is evidence that they are related to the change of methylation level caused by the change of folate metabolism. In conclusion, our study provides a novel model for the in-depth study of MTHFR gene and folate metabolism. Furthermore, our results reveal that folic acid has a dose-dependent effect on early cardiac development. Precise dosage of folic acid supplementation is crucial for the embryonic development of organisms.

Fms-like tyrosine kinase 3 is a regulator of the cardiac side population in mice

Fms-like tyrosine kinase 3 (Flt3) is a regulator of hematopoietic progenitor cells and a target of tyrosine kinase inhibitors. Flt3-targeting tyrosine kinase inhibitors can have cardiovascular side effects. Flt3 and its ligand (Flt3L) are expressed in the heart, but little is known about their physiological functions. Here, we show that cardiac side population progenitor cells (SP-CPCs) from mice produce and are responsive to Flt3L. Compared with wild-type, flt3L−/− mice have less SP-CPCs with less contribution of CD45−CD34+ cells and lower expression of genes related to epithelial-to-mesenchymal transition, cardiovascular development and stem cell differentiation. Upon culturing, flt3L−/− SP-CPCs show increased proliferation and less vasculogenic commitment, whereas Akt phosphorylation is lower. Notably, proliferation and differentiation can be partially restored towards wild-type levels in the presence of alternative receptor tyrosine kinase-activating growth factors signaling through Akt. The lower vasculogenic potential of flt3L−/− SP-CPCs reflects in decreased microvascularisation and lower systolic function of flt3L−/− hearts. Thus, Flt3 regulates phenotype and function of murine SP-CPCs and contributes to cellular and molecular properties that are relevant for their cardiovasculogenic potential.

Real Ambient Particulate Matter-Induced Myocardial Hypertrophy and Myocardial Lipotoxicity : Roles of PDGFRβ Methylation

Background: PM exposure can lead to myocardial hypertrophy, with a potential contribution via DNA methylation. Myocardial lipotoxicity is closely related to myocardial hypertrophy. But, myocardial lipotoxicity caused by PM has not been reported. PDGFRβ, a platelet-derived growth factor receptor, is also essential for normal cardiovascular development. However, It is unclear the role of PM-induced PDGFRβ methylation in myocardial hypertrophy and myocardial lipotoxicity. We investigated the effect of PDGFRβ methylation induced by PM on myocardial hypertrophy and myocardial lipotoxicity. Results: PDGFRβ methylation caused by PM decreased PDGFRβ mRNA and protein expression in C57BL/6J mouse hearts. Thus inhibiting gene expression in its downstream pathway, ultimately leading to cardiac hypertrophy. Disturbances of myocardial lipid metabolism caused by PM in AC16 cells and C57BL/6J mouse hearts were also observed. High expression of PDGFRβ in neonatal rat primary cardiomyocytes was found to activate its downstream pathway and ameliorate the effects of PM-induced cardiac hypertrophic activity. At the same time, adenovirus was used to induce high expression of PDGFRβ in C57BL/6J mice. It was found that PDGFRβ not only improved PM-induced cardiac hypertrophy, but also alleviated PM-induced myocardial lipotoxicity. Conclusions: PDGFRβ gene methylation may be one of the potential biomarkers of myocardial hypertrophy induced by PM exposure. And high expression of PDGFRβ may be a potential way to prevent myocardial hypertrophy and cardiac lipid metabolism disorder caused by PM exposure in mice.

Genetic Evidence for Congenital Vascular Disorders in Patients with VACTERL Association

Introduction The VACTERL association is a rare malformation complex, showing at least three anomalies of the following organ systems: vertebra, anorectum, heart and vessels, trachea and esophagus, genitourinary tract, and limbs. In addition to a multifactorial event, congenital vascular disorders are also discussed as triggers for the VACTERL association. The aim of this study was to determine whether there is a genetic background for vascular disorders triggering VACTERL association. Materials and Methods We performed a functional analysis on whole exome sequencing data of 21 patients with VACTERL or VACTERL-like phenotype using the online analysis tool “Database for Annotation, Visualization and Integrated Discovery (DAVID) v6.8.” The study was approved by the institutional ethics committee (approval no. 026–13). Written informed consent was obtained from all patients or their parents. Results We identified a total of 86 genetic variants (in 75 genes) classified as damaging (including probably damaging missense, nonsense, and frameshift variants), which are associated to cardiovascular development. Each investigated patient showed at least one damaging variant in genes associated to cardiovascular development. These variants were further reduced by significance in cardiovascular development to 39 genetic variants (in 33 genes). Of note, a pair of siblings, both presenting with cardiac and renal defects, had the same damaging variant in two different genes. Conclusion Our results indicate a genetic background for congenital vascular disorders in patients with VACTERL association. In line with the literature, our data suggest that genetic mutation led to vascular diseases, which in turn may cause malformations similar to the VACTERL association.

Spotlight on Isl1: A Key Player in Cardiovascular Development and Diseases

Cardiac transcription factors orchestrate a regulatory network controlling cardiovascular development. Isl1, a LIM-homeodomain transcription factor, acts as a key player in multiple organs during embryonic development. Its crucial roles in cardiovascular development have been elucidated by extensive studies, especially as a marker gene for the second heart field progenitors. Here, we summarize the roles of Isl1 in cardiovascular development and function, and outline its cellular and molecular modes of action, thus providing insights for the molecular basis of cardiovascular diseases.

First person – Jun-yi Zhu and Xiaohu Huang

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Disease Models & Mechanisms, helping early-career researchers promote themselves alongside their papers. Jun-yi Zhu and Xiaohu Huang are first authors on ‘ Pharmacological or genetic inhibition of hypoxia signaling attenuates oncogenic RAS-induced cancer phenotypes’, published in DMM. Jun-yi is an assistant professor in the lab of Zhe Han at the University of Maryland School of Medicine, Baltimore, MD, USA, investigating the use of Drosophila as a model to study human disease mechanisms and treatment approaches. Xiaohu is a postdoc in the same lab, investigating gene functions in cardiovascular development and genetic diseases.

Modulation of cell signalling and sulfation in cardiovascular development and disease

Sulf1/Sulf2 genes are highly expressed during early fetal cardiovascular development but down-regulated during later stages correlating with a number of cell signalling pathways in a positive or a negative manner. Immunocytochemical analysis confirmed SULF1/SULF2 expression not only in endothelial cell lining of blood vessels but also in the developing cardiomyocytes but not in the adult cardiomyocytes despite persisting at reduced levels in the adult endothelial cells. The levels of both SULFs in adult ischemic human hearts and in murine hearts following coronary occlusion increased in endothelial lining of some regional blood vessels but with little or no detection in the cardiomyocytes. Unlike the normal adult heart, the levels of SULF1 and SULF2 were markedly increased in the adult canine right-atrial haemangiosarcoma correlating with increased TGFβ cell signalling. Cell signalling relationship to ischaemia was further confirmed by in vitro hypoxia of HMec1 endothelial cells demonstrating dynamic changes in not only vegf and its receptors but also sulfotransferases and Sulf1 & Sulf2 levels. In vitro hypoxia of HMec1 cells also confirmed earlier up-regulation of TGFβ cell signalling revealed by Smad2, Smad3, ALK5 and TGFβ1 changes and later down-regulation correlating with Sulf1 but not Sulf2 highlighting Sulf1/Sulf2 differences in endothelial cells under hypoxia.

Observation of the Clinical Correlation between Carotid Artery Intima-Media Thickness and Cardiovascular Risk Factors in Hypertensive Patients under Microscope Images

With the development of social science and technology and people’s demand for exploring the micro world, digital microscope technology came into being. Microscope image processing technology has been widely used in industrial micromanipulation, biomedicine, and cultural relic identification and preservation. In order to in-depth study the use of microscope image technology to observe the thickness of the carotid artery intima-media in hypertensive patients to find out whether it is feasible to explore many risk factors for cardiovascular development, this article uses data analysis, concept analysis, and graphic construction methods to collect samples, analyzed the image, streamlined the algorithm, and created a microscope image that can study its risk factors. The severity of hypertension, diabetes, and other factors affects the thickness of carotid arteries and cardiovascular diseases. The results show that the longer the duration of hypertension, the higher the central and peripheral blood pressure, the higher the height, and the higher the central blood pressure, which is relatively low. The detection rate of elevated central blood pressure is higher (76.8%). The second group (53.6%) and the third group (49.2%) ( P < 0.008 ); older age, the central blood pressure is relatively high, and the detection rate of central blood pressure increases (75.5%). It is higher than normal blood pressure (24.5%), so it can be concluded that hypertension not only affects central blood pressure but also peripheral blood; height and age are independent factors that affect central blood pressure. It is basically realized that starting from the microscope image, many risk factors of cardiovascular disease have been successfully analyzed.

The Application of Single-Cell Technologies in Cardiovascular Research

Cardiovascular diseases (CVDs) are the leading cause of deaths in the world. The intricacies of the cellular composition and tissue microenvironment in heart and vasculature complicate the dissection of molecular mechanisms of CVDs. Over the past decade, the rapid development of single-cell omics technologies generated vast quantities of information at various biological levels, which have shed light on the cellular and molecular dynamics in cardiovascular development, homeostasis and diseases. Here, we summarize the latest single-cell omics techniques, and show how they have facilitated our understanding of cardiovascular biology. We also briefly discuss the clinical value and future outlook of single-cell applications in the field.