How cells acquire their fate is a fundamental question in developmental and regenerative biology. Multipotent progenitors undergo cell-fate restriction in response to cues from the microenvironment, the nature of which is poorly understood. In the case of the lymphatic system, venous cells from the cardinal vein are thought to generate lymphatic vessels through trans-differentiation. Here we show that in zebrafish, lymphatic progenitors arise from a previously uncharacterized niche of specialized angioblasts within the cardinal vein, which also generates arterial and venous fates. We further identify Wnt5b as a novel lymphatic inductive signal and show that it also promotes the ‘angioblast-to-lymphatic’ transition in human embryonic stem cells, suggesting that this process is evolutionarily conserved. Our results uncover a novel mechanism of lymphatic specification, and provide the first characterization of the lymphatic inductive niche. More broadly, our findings highlight the cardinal vein as a heterogeneous structure, analogous to the haematopoietic niche in the aortic floor.
Despite the clear major contribution of hyperlipidemia to the prevalence of cardiovascular disease in the developed world, the direct effects of lipoproteins on endothelial cells have remained obscure and are under debate. Here we report a previously uncharacterized mechanism of vessel growth modulation by lipoprotein availability. Using a genetic screen for vascular defects in zebrafish, we initially identified a mutation, stalactite (stl), in the gene encoding microsomal triglyceride transfer protein (mtp), which is involved in the biosynthesis of apolipoprotein B (ApoB)-containing lipoproteins. By manipulating lipoprotein concentrations in zebrafish, we found that ApoB negatively regulates angiogenesis and that it is the ApoB protein particle, rather than lipid moieties within ApoB-containing lipoproteins, that is primarily responsible for this effect. Mechanistically, we identified downregulation of vascular endothelial growth factor receptor 1 (VEGFR1), which acts as a decoy receptor for VEGF, as a key mediator of the endothelial response to lipoproteins, and we observed VEGFR1 downregulation in hyperlipidemic mice. These findings may open new avenues for the treatment of lipoprotein-related vascular disorders.
Formation and remodeling of vascular beds are complex processes orchestrated by multiple signaling pathways. Although it is well accepted that vessels of a particular organ display specific features that enable them to fulfill distinct functions, the embryonic origins of tissue-specific vessels and the molecular mechanisms regulating their formation are poorly understood. The subintestinal plexus of the zebrafish embryo comprises vessels that vascularize the gut, liver and pancreas and, as such, represents an ideal model in which to investigate the early steps of organ-specific vessel formation. Here, we show that both arterial and venous components of the subintestinal plexus originate from a pool of specialized angioblasts residing in the floor of the posterior cardinal vein (PCV). Using live imaging of zebrafish embryos, in combination with photoconvertable transgenic reporters, we demonstrate that these angioblasts undergo two phases of migration and differentiation. Initially, a subintestinal vein forms and expands ventrally through a Bone Morphogenetic Protein-dependent step of collective migration. Concomitantly, a Vascular Endothelial Growth Factor-dependent shift in the directionality of migration, coupled to the upregulation of arterial markers, is observed, which culminates with the generation of the supraintestinal artery. Together, our results establish the zebrafish subintestinal plexus as an advantageous model for the study of organ-specific vessel development and provide new insights into the molecular mechanisms controlling its formation. More broadly, our findings suggest that PCV-specialized angioblasts contribute not only to the formation of the early trunk vasculature, but also to the establishment of late-forming, tissue-specific vascular beds.
SummaryDevelopmental neuronal remodeling is an evolutionarily conserved mechanism required for precise wiring of nervous systems. Despite its fundamental role in neurodevelopment and proposed contribution to various neuropsychiatric disorders, the underlying mechanisms are largely unknown. Here, we uncover the fine temporal transcriptional landscape of Drosophila mushroom body γ neurons undergoing stereotypical remodeling. Our data reveal rapid and dramatic changes in the transcriptional landscape during development. Focusing on DNA binding proteins, we identify eleven that are required for remodeling. Furthermore, we sequence developing γ neurons perturbed for three key transcription factors required for pruning. We describe a hierarchical network featuring positive and negative feedback loops. Superimposing the perturbation-seq on the developmental expression atlas highlights a framework of transcriptional modules that together drive remodeling. Overall, this study provides a broad and detailed molecular insight into the complex regulatory dynamics of developmental remodeling and thus offers a pipeline to dissect developmental processes via RNA profiling.
Gene editing by CRISPR/Cas9 is commonly used to generate germline mutations or perform in vitro screens, but applicability for in vivo screening has so far been limited. Recently, it was shown that in Drosophila , Cas9 expression could be limited to a desired group of cells, allowing tissue-specific mutagenesis. Here, we thoroughly characterize tissue-specific (ts)CRISPR within the complex neuronal system of the Drosophila mushroom body. We report the generation of a library of gRNA-expressing plasmids and fly lines using optimized tools, which provides a valuable resource to the fly community. We demonstrate the application of our library in a large-scale in vivo screen, which reveals insights into developmental neuronal remodeling.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.