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Nat Commun. 2016 Jan 4;7:10253. doi: 10.1038/ncomms10253.

F-actin mechanics control spindle centring in the mouse zygote.

Author information

1
CIRB, Collège de France, and CNRS-UMR7241 and INSERM-U1050, Equipe labellisée Ligue contre le Cancer, Paris F-75005, France.
2
Université Evry Val d'Essonne, LAMBE, Boulevard F Mitterrand, Evry 91025, France.
3
UMR7600-CNRS/UPMC, 4 Place Jussieu, Paris F-75005, France.
4
Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
5
CNRS-UMR168, Paris F-75248, France.
6
UPMC, 4 Place Jussieu, Paris F-75248, France.
7
Institut Curie, Centre de Recherche, Laboratoire Physico-Chimie, Paris F-75248, France.

Abstract

Mitotic spindle position relies on interactions between astral microtubules nucleated by centrosomes and a rigid cortex. Some cells, such as mouse oocytes, do not possess centrosomes and astral microtubules. These cells rely only on actin and on a soft cortex to position their spindle off-centre and undergo asymmetric divisions. While the first mouse embryonic division also occurs in the absence of centrosomes, it is symmetric and not much is known on how the spindle is positioned at the exact cell centre. Using interdisciplinary approaches, we demonstrate that zygotic spindle positioning follows a three-step process: (1) coarse centring of pronuclei relying on the dynamics of an F-actin/Myosin-Vb meshwork; (2) fine centring of the metaphase plate depending on a high cortical tension; (3) passive maintenance at the cell centre. Altogether, we show that F-actin-dependent mechanics operate the switch between asymmetric to symmetric division required at the oocyte to embryo transition.

PMID:
26727405
PMCID:
PMC4725770
DOI:
10.1038/ncomms10253
[Indexed for MEDLINE]
Free PMC Article

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