PT  - JOURNAL ARTICLE
AU  - Ali Hashmi
AU  - Sham Tlili
AU  - Pierre Perrin
AU  - Alfonso Martinez-Arias
AU  - Pierre-François Lenne
TI  - Cell-state transitions and collective cell movement generate an endoderm-like region in gastruloids
AID  - 10.1101/2020.05.21.105551
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.05.21.105551
4099  - http://biorxiv.org/content/early/2020/06/10/2020.05.21.105551.short
4100  - http://biorxiv.org/content/early/2020/06/10/2020.05.21.105551.full
AB  - Shaping the animal body plan is a complex process that involves the spatial organization and patterning of different cell layers. Recent advances in live imaging have started to unravel the cellular choreography underlying this process in mammals, however, the sequence of events transforming an unpatterned cell ensemble into structured territories is largely unknown. Here, using 3D aggregates of mouse embryonic stem cells, we study the formation of one of the three germ layers, the endoderm. We show that the endoderm is generated from an epiblast-like state by a three-step mechanism: a release of islands of Ecadherin expressing cells, their flow toward the aggregate tip, and their segregation. Unlike the prevailing view, this mechanism does not require epithelial-to-mesenchymal transitions and vice-versa but rather a fragmentation, which is mediated by Wnt/β-catenin, and a sorting process. Our data emphasize the role of signaling and cell flows in the establishment of the body plan.Competing Interest StatementThe authors have declared no competing interest.