Light-activated Frizzled7 reveals a permissive role of non-canonical Wnt signaling in mesendoderm cell migration
Non-canonical Wnt-signaling plays a central role for coordinated cell polarization and directed migration in metazoan development. While spatiotemporally restricted activation of non-canonical Wnt-signaling drives cell polarization in epithelial tissues, it remains unclear whether such instructive activity is also critical for directed mesenchymal cell migration. Here, we developed a light-activated version of the non-canonical Wnt receptor Frizzled 7 (Fz7) to analyze how restricted activation of non-canonical Wnt-signaling affects directed anterior axial mesendoderm (prechordal plate, ppl) cell migration within the zebrafish gastrula. We found that Fz7 signaling is required for ppl cell protrusion formation and migration, and that spatiotemporally restricted ectopic activation is capable of redirecting their migration. Finally, we show that uniform activation of Fz7 signaling in ppl cells fully rescues defective directed cell migration in fz7 mutant embryos. Together, our findings reveal that in contrast to the situation in epithelial cells, non-canonical Wnt-signaling functions permissively rather than instructively in directed mesenchymal cell migration during gastrulation.
All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 1-5, and figure supplements S1, S2, and S4-10
Article and author information
European Research Council (742573)
- Carl-Philipp Heisenberg
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: Experiments involving zebrafish reported in this study included the creation and maintenance of transgenic mutant lines of zebrafish. In my role as Ethics Officer at IST Austria, I herewith confirm that the use of animals for experimental purposes within the scope of this study does not require the approval of the Ethics Committee at IST Austria. In line with EU directive 2010/63/EU on the protection of animals used for scientific purposes, Austrian legislation requires that the use of animals for scientific purposes has to be approved by the respective unit at the Federal Ministry of Education, Science, and Research. This process includes an ethical evaluation of the planned experiments as part of the harm-benefit analysis. Beyond that no further approval by the Ethics Committee at IST Austria is required. The respective approval number that covers the experiments that were performed is 66.018/0010-WF/II/3b/2014.Yours sincerely,Dr. Verena SeibothEthics Officer
- Didier Y Stainier, Max Planck Institute for Heart and Lung Research, Germany
- Received: September 17, 2018
- Accepted: January 14, 2019
- Accepted Manuscript published: January 16, 2019 (version 1)
- Version of Record published: February 6, 2019 (version 2)
© 2019, Čapek et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
- Page views
Article citation count generated by polling the highest count across the following sources: Scopus, Crossref, PubMed Central.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
- Cell Biology
- Stem Cells and Regenerative Medicine
Following acute injury, the capillary vascular bed in the lung must be repaired to reestablish gas exchange with the external environment. Little is known about the transcriptional and signaling factors that drive pulmonary endothelial cell (EC) proliferation and subsequent regeneration of pulmonary capillaries, as well as their response to stress. Here, we show that the transcription factor Atf3 is essential for the regenerative response of the mouse pulmonary endothelium after influenza infection. Atf3 expression defines a subpopulation of capillary ECs enriched in genes involved in endothelial development, differentiation, and migration. During lung alveolar regeneration, this EC population expands and increases the expression of genes involved in angiogenesis, blood vessel development, and cellular response to stress. Importantly, endothelial cell-specific loss of Atf3 results in defective alveolar regeneration, in part through increased apoptosis and decreased proliferation in the endothelium. This leads to the general loss of alveolar endothelium and persistent morphological changes to the alveolar niche, including an emphysema-like phenotype with enlarged alveolar airspaces lined with regions that lack vascular investment. Taken together, these data implicate Atf3 as an essential component of the vascular response to acute lung injury that is required for successful lung alveolar regeneration.
- Cell Biology
- Microbiology and Infectious Disease
African trypanosomes proliferate as bloodstream forms (BSFs) and procyclic forms in the mammal and tsetse fly midgut, respectively. This allows them to colonise the host environment upon infection and ensure life cycle progression. Yet, understanding of the mechanisms that regulate and drive the cell replication cycle of these forms is limited. Using single-cell transcriptomics on unsynchronised cell populations, we have obtained high resolution cell cycle regulated (CCR) transcriptomes of both procyclic and slender BSF Trypanosoma brucei without prior cell sorting or synchronisation. Additionally, we describe an efficient freeze–thawing protocol that allows single-cell transcriptomic analysis of cryopreserved T. brucei. Computational reconstruction of the cell cycle using periodic pseudotime inference allowed the dynamic expression patterns of cycling genes to be profiled for both life cycle forms. Comparative analyses identify a core cycling transcriptome highly conserved between forms, as well as several genes where transcript levels dynamics are form specific. Comparing transcript expression patterns with protein abundance revealed that the majority of genes with periodic cycling transcript and protein levels exhibit a relative delay between peak transcript and protein expression. This work reveals novel detail of the CCR transcriptomes of both forms, which are available for further interrogation via an interactive webtool.