Cell autonomous sorting and surface positioning in the formation of primitive endoderm in embryoid bodies

Abstract

The differentiation and formation of the primitive endoderm in early embryos can be mimicked in vitro by the aggregation of embryonic stem cells to form embryoid bodies. We present morphological evidence that primitive endoderm cells often first locate in the interior of embryoid bodies and subsequently migrate to the surface. Cell mixing experiments indicate that surface positioning is an intrinsic property of endoderm epithelial cells. Moreover, Disabled-2 (Dab2) is required for surface sorting and positioning of the endoderm cells: when Dab2 expression was eliminated, the differentiated endoderm epithelial cells distributed throughout the interior of the embryoid bodies. Surprisingly, E-cadherin is dispensable for primitive endoderm differentiation and surface sorting in embryoid bodies. These results support the model that primitive endoderm cells first emerge in the interior of the inner cell mass and are subsequently sorted to the surface to form the primitive endoderm.

Stk40 links the pluripotency factor Oct4 to the Erk/MAPK pathway and controls extraembryonic endoderm differentiation

“…Wild-type ESCs spontaneously differentiated into cystic EBs containing heterogeneous cell types representing all three germ layers and an outer layer of ExEn cells when cultured in suspension (18). Remarkably, the outer layer of EBs aggregated from Stk40 overexpressing ESCs was more prominent and thicker than that of control EBs (Fig.…”

A role for PDGF signaling in expansion of the extra-embryonic endoderm lineage of the mouse blastocyst

“…These paradigms have proved invaluable for studying diverse aspects of ExEn biology (Coucouvanis and Martin, 1999;Fujikura et al, 2002;Rula et al, 2007;Shimosato et al, 2007;Yang et al, 2007). We used the Pdgfra H2B-GFP reporter (Hamilton et al, 2003;Plusa et al, 2008) to visualize Pdgfra expression in these assays.…”

Geometric Control of Cardiomyogenic Induction in Human Pluripotent Stem Cells

“…Geometric relationships also vary with aggregate size, given that the ratio of the surface area to volume of a sphere decreases with increasing sphere size. It has been widely published in reports examining spatial organization during EB development that one of the first events involves the organization of an outer layer of ExE cells surrounding a pluripotent epiblast-like core (Coucouvanis and Martin 1995;Abe, Niwa et al 1996;Coucouvanis and Martin 1999;Rula, Cai et al 2007;Ungrin, Joshi et al 2008;Moore, Cai et al 2009). Given that as aggregate size increases, there are fewer cells on the surface relative to interior cells, and that the outer layer of cells consists of ExE cells, it may be that the frequency of ExE cells that develop in an aggregate decreases with increasing aggregate size.…”

“…It has been previously reported that primitive endoderm cells do not originate at the EB surface but first appear throughout the EB and subsequently migrate to the surface to form an epithelial layer (Rula, Cai et al 2007;Moore, Cai et al 2009). Early aggregates of F9 embryonal carcinoma cells (1 and 2 days old) are largely made up of undifferentiated cells but do contain a few primitive endoderm cells, detected by the expression of GATA4 and the cytoplasmic endocytic adaptor Dab2 (Rula, Cai et al 2007), which are mainly located in the interior of some of the spheroids with some also present on the surface. By day 4 and 7 of aggregate culture primitive endoderm cells are located on the outer layer of the aggregates, probably by migration, and only a few differentiated cells are located in the interior.…”