Cdc42 activation by endothelin regulates neural crest cell migration in the cardiac outflow tract

Polarity and migration of cranial and cardiac neural crest cells: underlying molecular mechanisms and disease implications

The Neural Crest cells are multipotent progenitor cells formed at the neural plate border that differentiate and give rise to a wide range of cell types and organs. Directional migration of NC cells and their correct positioning at target sites are essential during embryonic development, and defects in these processes results in congenital diseases. The NC migration begins with the epithelial-mesenchymal transition and extracellular matrix remodeling. The main cellular mechanisms that sustain this migration include contact inhibition of locomotion, co-attraction, chemotaxis and mechanical cues from the surrounding environment, all regulated by proteins that orchestrate cell polarity and motility. In this review we highlight the molecular mechanisms involved in neural crest cell migration and polarity, focusing on the role of small GTPases, Heterotrimeric G proteins and planar cell polarity complex. Here, we also discuss different congenital diseases caused by altered NC cell migration.

Cyclin-dependent kinase 13 is indispensable for normal mouse heart development

Congenital heart disease (CHD) has an incidence of approximately 1%. Over the last decade, sequencing studies including large cohorts of individuals with CHD have begun to unravel the genetic mechanisms underpinning CHD. This includes the identification of variants in cyclin-dependent kinase 13 (CDK13), in individuals with syndromic CHD. CDK13 encodes a serine/threonine protein kinase. The cyclin partner of CDK13 is cyclin K; this complex is thought to be important in transcription and RNA processing. Pathogenic variants in CDK13 cause CDK13-related disorder in humans, characterised by intellectual disability and developmental delay, recognisable facial features, feeding difficulties and structural brain defects, with 35% of individuals having CHD. To obtain a greater understanding for the role that this essential protein kinase plays in embryonic heart development, we have analysed a presumed loss of function Cdk13 transgenic mouse model (Cdk13tm1b). The homozygous mutants were embryonically lethal in most cases by E15.5. X-gal staining showed Cdk13 expression localised to developing facial regions, heart and surrounding areas at E10.5, whereas at E12.5, it was more widely present. In the E15.5 heart, staining was seen throughout. RT-qPCR showed significant reduction in Cdk13 transcript expression in homozygous compared with WT and heterozygous hearts at E10.5 and E12.5. Detailed morphological 3D analysis of embryonic and postnatal hearts was performed using high-resolution episcopic microscopy, which affords a more detailed analysis of structures such as cardiac valve leaflets and endocardial cushions, compared with more traditional histological techniques. We show that both the homozygous and heterozygous Cdk13tm1b mutants exhibit a range of CHD, including ventricular septal defects, bicuspid aortic valve, double outlet right ventricle and atrioventricular septal defects. 100% (n = 4) of homozygous hearts displayed CHD. Differential expression was seen in Cdk13tm1b homozygous mutants for two genes known to be necessary for normal heart development. The types of defects, and the presence of CHD in heterozygous mice (17.02%, n = 8/47), are consistent with the CDK13-related disorder phenotype in humans. This study provides important insights into the effects of reduced function of CDK13 in the mouse heart and contributes to our understanding of the mechanism behind this disorder as a cause of CHD.

Endothelin signaling in development

Since the discovery of endothelin 1 (EDN1) in 1988, the role of endothelin ligands and their receptors in the regulation of blood pressure in normal and disease states has been extensively studied. However, endothelin signaling also plays crucial roles in the development of neural crest cell-derived tissues. Mechanisms of endothelin action during neural crest cell maturation have been deciphered using a variety of in vivo and in vitro approaches, with these studies elucidating the basis of human syndromes involving developmental differences resulting from altered endothelin signaling. In this Review, we describe the endothelin pathway and its functions during the development of neural crest-derived tissues. We also summarize how dysregulated endothelin signaling causes developmental differences and how this knowledge may lead to potential treatments for individuals with gene variants in the endothelin pathway.

Time to go: neural crest cell epithelial-to-mesenchymal transition

Neural crest cells (NCCs) are a dynamic, multipotent, vertebrate-specific population of embryonic stem cells. These ectodermally-derived cells contribute to diverse tissue types in developing embryos including craniofacial bone and cartilage, the peripheral and enteric nervous systems and pigment cells, among a host of other cell types. Due to their contribution to a significant number of adult tissue types, the mechanisms that drive their formation, migration and differentiation are highly studied. NCCs have a unique ability to transition from tightly adherent epithelial cells to mesenchymal and migratory cells by altering their polarity, expression of cell-cell adhesion molecules and gaining invasive abilities. In this Review, we discuss classical and emerging factors driving NCC epithelial-to-mesenchymal transition and migration, highlighting the role of signaling and transcription factors, as well as novel modifying factors including chromatin remodelers, small RNAs and post-translational regulators, which control the availability and longevity of major NCC players.

lncRNA deleted in lymphocytic leukaemia 1 (DLEU1) promotes the migration and invasion of human embryonic trophoblast cells

To investigate the roles of lncRNA deleted in lymphocytic leukaemia 1 (DLEU1) on migration and invasion of human trophoblast cells. Human chorionic trophoblast cell line HTR8/SVneo was cultured and transfected using lncRNA DLEU1 small interfering RNA. Real-time quantitative polymerase chain reaction was used to detect lncRNA DLEU1 expression. The activity of migration regulatory protein CDC42 was detected by western blot. The downstream miRNA targets of lncRNA and mRNAs targeted by corresponding miRNAs were respectively predicted using bioinformatics analyses. Compared with the control group, the expression of lncRNA DLEU1 in the small interfering RNA group was significantly decreased (P < 0.05). There was no significant change in cell proliferation capacity for transfected cells (lncRNA DLEU1 siRNA-1, P = 0.537; lncRNA DLEU1 siRNA-2, P = 0.384), but cell migration (lncRNA DLEU1 siRNA-1, P = 0.025; lncRNA DLEU1 siRNA-2, P = 0.019) and invasion (lncRNA DLEU1 siRNA-1, P = 0.0327; lncRNA DLEU1 siRNA-2, P = 0.021) was significantly reduced. CDC42 activity in the lncRNA DLEU1 knockdown group decreased and the phosphorylation of cofilin increased. Therefore, downregulation of lncRNA DLEU1 suppressed the migration and invasion of human trophoblast cells.

Adverse effects of nicotine on cardiogenic differentiation from human embryonic stem cells detected by single-cell RNA sequencing

Tobacco smoking was one of the important adverse factors for congenital heart disease. The effects of nicotine, the main component of tobacco, on human embryonic cardiogenesis and related mechanisms remain poorly understood. This work used single-cell RNA sequencing to investigate the effects of nicotine on human embryonic stem cell (hESC) line H9 and its underlying mechanisms during cardiac differentiation. H9 was cultured in feeder-free medium and differentiated in cardiac condition medium when cells reached 90% confluent. Cell viability was detected by MTT after different concentration of nicotine treatment. Different expressed genes during cardiac differentiation was analyzed by single-cell RNA sequencing (scRNA-seq). Key gene expressions were confirmed by qPCR and Western blot. Results showed that 0.1μM-10μM nicotine did not affect H9 cell proliferation. Nicotine 1 μM down-regulated cardiac progenitor cell, mesoderm cell, smooth muscle cell and neural crest cell relatively. Snail1/2 regulating endocardial cushion development were downregulated apparently at differention day 6. Nicotine didn't affect bry-1 and mesp-1 but inhibited cardiac transcript factors. Consequently, the expression of cTnI, a marker of cardiomyocytes was decreased significantly. The data suggest direct adverse effects of nicotine on heart development at the single-cell level and offer a new approach for estimate drug and environmental toxicity on the pathogenesis of the embryonic cardiovascular system development.