title: Pulsatile cell-autonomous contractility drives compaction in the mouse embryo.
abstract: Mammalian embryos initiate morphogenesis with compaction, which is essential for specifying the first lineages of the blastocyst. The 8-cell-stage mouse embryo compacts by enlarging its cell-cell contacts in a Cdh1-dependent manner. It was therefore proposed that Cdh1 adhesion molecules generate the forces driving compaction. Using micropipette aspiration to map all tensions in a developing embryo, we show that compaction is primarily driven by a twofold increase in tension at the cell-medium interface. We show that the principal force generator of compaction is the actomyosin cortex, which gives rise to pulsed contractions starting at the 8-cell stage. Remarkably, contractions emerge as periodic cortical waves when cells are disengaged from adhesive contacts. In line with this, tension mapping of mzCdh1(-/-) embryos suggests that Cdh1 acts by redirecting contractility away from cell-cell contacts. Our study provides a framework to understand early mammalian embryogenesis and original perspectives on evolutionary conserved pulsed contractions.
authors.affiliation: European Molecular Biology Laboratory, Meyerhofstrasse 1 69117 Heidelberg, Germany.
authors.forename: Jean-Léon
authors.initials: JL
authors.lastname: Maître
authors.affiliation: European Molecular Biology Laboratory, Meyerhofstrasse 1 69117 Heidelberg, Germany.
authors.forename: Ritsuya
authors.initials: R
authors.lastname: Niwayama
authors.affiliation: European Molecular Biology Laboratory, Meyerhofstrasse 1 69117 Heidelberg, Germany.
authors.forename: Hervé
authors.initials: H
authors.lastname: Turlier
authors.affiliation: European Molecular Biology Laboratory, Meyerhofstrasse 1 69117 Heidelberg, Germany.
authors.forename: François
authors.initials: F
authors.lastname: Nédélec
authors.affiliation: European Molecular Biology Laboratory, Meyerhofstrasse 1 69117 Heidelberg, Germany.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hiiragi
mesh_terms: D000205:Actomyosin / Q000502:physiology; D000818:Animals; D001757:Blastomeres / Q000502:physiology*; D064200:Cdh1 Proteins / Q000235:genetics / Q000502:physiology; D002448:Cell Adhesion / Q000502:physiology; D002450:Cell Communication / Q000502:physiology; D048430:Cell Shape / Q000502:physiology; D004622:Embryo, Mammalian / Q000166:cytology / Q000196:embryology* / Q000502:physiology*; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D007700:Kinetics; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D018994:Myosin Light Chains / Q000378:metabolism; D013997:Time Factors; D059008:Time-Lapse Imaging
chemical_list: D064200:Cdh1 Proteins; C577585:Fzr1 protein, mouse; D018994:Myosin Light Chains; D049452:Green Fluorescent Proteins; D000205:Actomyosin