The Apical Domain Is Required and Sufficient for the First Lineage Segregation in the Mouse Embryo

Publication date: 6 February 2017
Source:Developmental Cell, Volume 40, Issue 3
Author(s): Ekaterina Korotkevich, Ritsuya Niwayama, Aurélien Courtois, Stefanie Friese, Nicolas Berger, Frank Buchholz, Takashi Hiiragi
Mammalian development begins with segregation of the extra-embryonic trophectoderm from the embryonic lineage in the blastocyst. While cell polarity and adhesion play key roles, the decisive cue driving this lineage segregation remains elusive. Here, to study symmetry breaking, we use a reduced system in which isolated blastomeres recapitulate the first lineage segregation. We find that in the 8-cell stage embryo, the apical domain recruits a spindle pole to ensure its differential distribution upon division. Daughter cells that inherit the apical domain adopt trophectoderm fate. However, the fate of apolar daughter cells depends on whether their position within the embryo facilitates apical domain formation by Cdh1-independent cell contact. Finally, we develop methods for transplanting apical domains and show that acquisition of this domain is not only required but also sufficient for the first lineage segregation. Thus, we provide mechanistic understanding that reconciles previous models for symmetry breaking in mouse development.

Graphical abstract

Teaser

Korotkevich et al. use a reduced system to study symmetry breaking in early mouse development and show that Cdh1-independent contact asymmetry directs temporally controlled apical domain formation, which is necessary and sufficient for segregating the first cell lineages.


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