Biology subjects

Stainier, D. Y. R.

Publications and source records attributed to Stainier, D. Y. R..

26 records · Page 2Linked to original sources

bioRxiv2019

Cardiac function modulates endocardial cell dynamics to shape the cardiac outflow tract

Physical forces are important participants in the cellular dynamics that shape developing organs. During heart formation, for example, contractility and blood flow generate biomechanical cues that influence patterns of cell behavior. Here, we address the interplay between function and form during the assembly of the cardiac outflow tract (OFT), a crucial connection between the heart and vasculature that develops while circulation is underway. In zebrafish, we find that the OFT expands via accrual of both endocardial and myocardial cells. However, when cardiac function is disrupted, OFT endocardial growth ceases, accompanied by reduced proliferation and reduced addition of cells from adjacent vessels. The TGF{beta} receptor Acvrl1 is required for addition of endocardial cells, but not for their proliferation, indicating distinct regulation of these essential cell behaviors. Together, our results suggest that cardiac function modulates OFT morphogenesis by triggering endocardial cell accumulation that induces OFT lumen expansion and shapes OFT dimensions.

developmental biology↗

bioRxiv2019

Cardiac valve regeneration in adult zebrafish: importance of TGF-β signaling in new tissue formation

Cardiac valve disease can lead to severe cardiac dysfunction and is thus a frequent cause of morbidity and mortality. Its main treatment is valve replacement, which is currently greatly limited by the poor recellularization and tissue formation potential of the implanted valves. As we still lack suitable animal models to identify modulators of these processes, here we used the adult zebrafish and found that, upon valve decellularization, they initiate a striking regenerative program that leads to the formation of new functional valves. After injury, endothelial and kidney marrow-derived cells undergo cell cycle re-entry and differentiate into new extracellular matrix-secreting valve cells. The Transforming Growth Factor beta (TGF{beta}) signaling pathway promotes this process by enhancing progenitor cell proliferation as well as valve cell differentiation. These findings reveal a key role for TGF{beta} signaling in valve regeneration and also establish the zebrafish as a model to identify and test factors promoting valve recellularization and growth.

developmental biology↗

bioRxiv2018

Induction of Interferon-Stimulated Genes and Cellular Stress Pathways by Morpholinos

The phenotypes caused by morpholino-mediated interference of gene function in zebrafish are often not observed in the corresponding mutant(s). We took advantage of the availability of a relatively large collection of transcriptomic datasets to identify common signatures that characterize morpholino-injected animals (morphants). In addition to the previously reported activation of tp53 expression, we observed increased expression of the interferon-stimulated genes (ISGs), isg15 and isg20, an extrinsic cell death pathway gene, casp8, and other cellular stress response genes including phlda3, mdm2 and gadd45aa. Studies involving segmentation stage embryos were more likely to show upregulation of these genes. We also found that these genes could be upregulated by an increasing dose of egfl7 morpholino, or high doses of standard control morpholino. Thus, these data suggest that morpholinos can stimulate the innate immune response in zebrafish, as was recently reported in Xenopus.

genetics↗

bioRxiv2018

Myh10 deficiency leads to defective extracellular matrix remodeling and pulmonary disease

Impaired alveolar formation and maintenance are features of many pulmonary diseases that are associated with significant morbidity and mortality. In a forward genetic screen for modulators of mouse lung development, we identified the non-muscle myosin II heavy chain gene, Myh10. Myh10 mutant pups exhibit cyanosis and respiratory distress, and die shortly after birth from differentiation defects in alveolar epithelium and mesenchyme. From omics analyses and follow up studies, we find decreased Thrombospondin expression accompanied with increased matrix metalloproteinase activity in both mutant lungs and cultured mutant fibroblasts, as well as disrupted extracellular matrix (ECM) remodeling. Loss of Myh10 specifically in mesenchymal cells results in ECM deposition defects and alveolar simplification. Notably, MYH10 expression is down-regulated in the lung of emphysema patients. Altogether, our findings reveal critical roles for Myh10 in alveologenesis at least in part via the regulation of ECM remodeling, which may contribute to the pathogenesis of emphysema.

developmental biology↗

bioRxiv2018

The transmembrane protein Crb2a regulates cardiomyocyte apicobasal polarity and adhesion in zebrafish

Tissue morphogenesis requires changes in cell-cell adhesion as well as in cell shape and polarity. Cardiac trabeculation is a morphogenetic process essential to form a functional ventricular wall. Here we show that zebrafish hearts lacking Crb2a, a component of the Crumbs polarity complex, display compact wall integrity defects and fail to form trabeculae. Crb2a localization is very dynamic, at a time when other cardiomyocyte junctional proteins also relocalize. Before the initiation of cardiomyocyte delamination to form the trabecular layer, Crb2a is expressed in all ventricular cardiomyocytes colocalizing with the junctional protein ZO-1. Subsequently, Crb2a becomes localized all along the apical membrane of compact layer cardiomyocytes and is downregulated by those delaminating. We show that blood flow and Nrg/ErbB2 signaling regulate these Crb2a localization changes. crb2a mutants display a multilayered wall with polarized cardiomyocytes, a unique phenotype. Our data further indicate that Crb2a regulates cardiac trabeculation by controlling the localization of tight and adherens junctions in cardiomyocytes. Importantly, transplantation data show that Crb2a controls trabeculation in a CM-autonomous manner. Altogether, our study reveals a critical role for Crb2a during cardiac development.\n\nSummary statementInvestigation of the Crumbs polarity protein Crb2a in zebrafish reveals a novel role in cardiac development via regulation of cell-cell adhesion and apicobasal polarity.

developmental biology↗

bioRxiv2018

Genetic compensation is triggered by mutant mRNA degradation

Genetic compensation by transcriptional modulation of related gene(s) (also known as transcriptional adaptation) has been reported in numerous systems 1-3; however, whether and how such a response can be activated in the absence of protein feedback loops is unknown. Here, we develop and analyze several models of transcriptional adaptation in zebrafish and mouse that we show are not caused by loss of protein function. We find that the increase in transcript levels is due to enhanced transcription, and observe a correlation between the levels of mutant mRNA decay and transcriptional upregulation of related genes. To assess the role of mutant mRNA degradation in triggering transcriptional adaptation, we use genetic and pharmacological approaches and find that mRNA degradation is indeed required for this process. Notably, uncapped RNAs, themselves subjected to rapid degradation, can also induce transcriptional adaptation. Next, we generate alleles that fail to transcribe the mutated gene and find that they do not show transcriptional adaptation, and exhibit more severe phenotypes than those observed in alleles displaying mutant mRNA decay. Transcriptome analysis of these different alleles reveals the upregulation of hundreds of genes with enrichment for those showing sequence similarity with the mutated genes mRNA, suggesting a model whereby mRNA degradation products induce the response via sequence similarity. These results expand the role of the mRNA surveillance machinery in buffering against mutations by triggering the transcriptional upregulation of related genes. Besides implications for our understanding of disease-causing mutations, our findings will help design mutant alleles with minimal transcriptional adaptation-derived compensation.

genetics↗

bioRxiv2018

The potassium channel KCNJ13 is essential for smooth muscle cytoskeletal organization during mouse tracheal tubulogenesis

Tubulogenesis is essential for the formation and function of internal organs. One such organ is the trachea, which allows gas exchange between the external environment and the lungs. However, the cellular and molecular mechanisms underlying tracheal tube development remain poorly understood. Here, we show that the potassium channel KCNJ13 is a critical modulator of tracheal tubulogenesis. We identify Kcnj13 in an ethylnitrosourea forward genetic screen for regulators of mouse respiratory organ development. Kcnj13 mutants exhibit a shorter trachea as well as defective smooth muscle (SM) cell alignment and polarity. KCNJ13 is essential to maintain ion homeostasis in tracheal SM cells, which is required for actin polymerization. This process appears to be mediated, at least in part, through activation of the actin regulator AKT, as pharmacological increase of AKT phosphorylation ameliorates the Kcnj13 mutant trachea phenotypes. These results provide insights into the role of ion homeostasis in cytoskeletal organization during tubulogenesis.

developmental biology↗

bioRxiv2018

Endothelial and non-endothelial responses to estrogen excess during development lead to vascular malformations

Excess estrogen signaling is associated with vascular malformations and pathologic angiogenesis, as well as tumor progression and metastasis. Yet, how dysregulated estrogen signaling impacts vascular morphogenesis in vivo remains elusive. Here we use live imaging of zebrafish embryos to determine the effects of excess estrogen signaling on the developing vasculature. We find that excess estrogens during development induce intersegmental vessel defects, endothelial cell-cell disconnections, and a shortening of the circulatory loop due to arterial-venous segregation defects. Whole-mount in situ hybridization and qPCR analyses reveal that excess estrogens negatively regulate Sonic hedgehog (Hh)/Vegf/Notch signaling. Activation of Hh signaling with SAG partially rescues the estrogen-induced vascular defects. Similarly, increased vegfaa bioavailability, using flt1/vegfr1 mutants or embryos overexpressing vegfaa165, also partially rescues the estrogen-induced vascular defects. We further find that excess estrogens promote aberrant endothelial cell (EC) migration, possibly as a result of increased PI3K and Rho GTPase signaling. Using estrogen receptor mutants and pharmacological studies, we show that Esr1 and the G-protein coupled estrogen receptor (Gper1) are the main receptors driving the estrogen-induced vascular defects. Mosaic overexpression of gper1 in ECs promotes vascular disconnections and aberrant migration, whereas no overt vascular defects were observed in mosaic embryos overexpressing wild-type or constitutively active nuclear estrogen receptors in their ECs. In summary, developmental estrogen excess leads to a mispatterning of the forming vasculature. Gper1 can act cell-autonomously in ECs to cause disconnections and aberrant migration, whilst Esr signaling predominantly downregulates Hh/Vegf/Notch signaling leading to impaired angiogenesis and defective arterial-venous segregation.\n\nSubject codes: angiogenesis, animal models of human disease, mechanisms, vascular biology.

developmental biology↗