Multiscale analysis of single and double maternal-zygotic Myh9 and Myh10 mutants during mouse preimplantation development
- Institut Curie, France
Abstract
During the first days of mammalian development, the embryo forms the blastocyst, the structure responsible for implanting the mammalian embryo. Consisting of an epithelium enveloping the pluripotent inner cell mass and a fluid-filled lumen, the blastocyst results from a series of cleavages divisions, morphogenetic movements and lineage specification. Recent studies identified the essential role of actomyosin contractility in driving the cytokinesis, morphogenesis and fate specification leading to the formation of the blastocyst. However, the preimplantation development of contractility mutants has not been characterized. Here, we generated single and double maternal-zygotic mutants of non-muscle myosin II heavy chains (NMHC) to characterize them with multiscale imaging. We find that Myh9 (NMHC II-A) is the major NMHC during preimplantation development as its maternal-zygotic loss causes failed cytokinesis, increased duration of the cell cycle, weaker embryo compaction and reduced differentiation, whereas Myh10 (NMHC II-B) maternal-zygotic loss is much less severe. Double maternal-zygotic mutants for Myh9 and Myh10 show a much stronger phenotype, failing most attempts of cytokinesis. We find that morphogenesis and fate specification are affected but nevertheless carry on in a timely fashion, regardless of the impact of the mutations on cell number. Strikingly, even when all cell divisions fail, the resulting single-celled embryo can initiate trophectoderm differentiation and lumen formation by accumulating fluid in increasingly large vacuoles. Therefore, contractility mutants reveal that fluid accumulation is a cell-autonomous process and that the preimplantation program carries on independently of successful cell division.
Data availability
The microscopy data, ROI and analyses are available on the following repository under a CC BY- NC-SA license: https://ressources.curie.fr/mzmyh/
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Single-cell RNA-Seq reveals dynamic, random monoallelic gene expression in mammalian cellsNCBI Gene Expression Omnibus, GSE45719.
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Tracing pluripotency of human early embryos and embryonic stem cells by single cell RNA-seqNCBI Gene Expression Omnibus, GSE36552.
Article and author information
Author details
Markus Frederik Schliffka
Anna-Francesca Tortorelli
Ludmilla de Plater
Funding
Institut des sciences biologiques
- Diane Pelzer
Agence Nationale de la Recherche (ANR-11-LABX-0044)
- Jean-Léon Maître
Agence Nationale de la Recherche (ANR-10-IDEX-0001-02)
- Jean-Léon Maître
Association Nationale de la Recherche et de la Technologie (2019/0253)
- Markus Frederik Schliffka
H2020 Marie Skłodowska-Curie Actions (666003)
- Özge Özgüç
Institut National de la Santé et de la Recherche Médicale
- Jean-Léon Maître
Fondation pour la Recherche Médicale
- Özge Özgüç
Fondation Schlumberger pour l'Education et la Recherche
- Jean-Léon Maître
H2020 European Research Council (ERC-2017-StG 757557)
- Jean-Léon Maître
European Molecular Biology Organisation
- Jean-Léon Maître
Université de Recherche Paris Sciences et Lettres (17-CONV-0005)
- Jean-Léon Maître
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All animal work is performed in the animal facility at the Institut Curie, with permission by the institutional veterinarian overseeing the operation (APAFIS #11054- 2017082914226001). The animal facilities are operated according to international animal welfare rules.
Copyright
© 2021, Schliffka 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.
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Multiscale analysis of single and double maternal-zygotic Myh9 and Myh10 mutants during mouse preimplantation development
eLife 10:e68536.
https://doi.org/10.7554/eLife.68536
Further reading
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- Cell Biology
- Developmental Biology
Eukaryotic cells depend on exocytosis to direct intracellularly synthesized material toward the extracellular space or the plasma membrane, so exocytosis constitutes a basic function for cellular homeostasis and communication between cells. The secretory pathway includes biogenesis of secretory granules (SGs), their maturation and fusion with the plasma membrane (exocytosis), resulting in release of SG content to the extracellular space. The larval salivary gland of Drosophila melanogaster is an excellent model for studying exocytosis. This gland synthesizes mucins that are packaged in SGs that sprout from the trans-Golgi network and then undergo a maturation process that involves homotypic fusion, condensation, and acidification. Finally, mature SGs are directed to the apical domain of the plasma membrane with which they fuse, releasing their content into the gland lumen. The exocyst is a hetero-octameric complex that participates in tethering of vesicles to the plasma membrane during constitutive exocytosis. By precise temperature-dependent gradual activation of the Gal4-UAS expression system, we have induced different levels of silencing of exocyst complex subunits, and identified three temporarily distinctive steps of the regulated exocytic pathway where the exocyst is critically required: SG biogenesis, SG maturation, and SG exocytosis. Our results shed light on previously unidentified functions of the exocyst along the exocytic pathway. We propose that the exocyst acts as a general tethering factor in various steps of this cellular process.
