Physikalische Biologie, Buchmann Institute for Molecular Life Sciences, Goethe-Universität Frankfurt am Main, Frankfurt am Main, Germany.
Department of Biology and Biochemistry, University of Bath, Bath, England, United Kingdom.
PLoS One. 2020 May 15;15(5):e0233030. doi: 10.1371/journal.pone.0233030. eCollection 2020.
During mammalian blastocyst development, inner cell mass (ICM) cells differentiate into epiblast (Epi) or primitive endoderm (PrE). These two fates are characterized by the expression of the transcription factors NANOG and GATA6, respectively. Here, we investigate the spatio-temporal distribution of NANOG and GATA6 expressing cells in the ICM of the mouse blastocysts with quantitative three-dimensional single cell-based neighbourhood analyses. We define the cell neighbourhood by local features, which include the expression levels of both fate markers expressed in each cell and its neighbours, and the number of neighbouring cells. We further include the position of a cell relative to the centre of the ICM as a global positional feature. Our analyses reveal a local three-dimensional pattern that is already present in early blastocysts: 1) Cells expressing the highest NANOG levels are surrounded by approximately nine neighbours, while 2) cells expressing GATA6 cluster according to their GATA6 levels. This local pattern evolves into a global pattern in the ICM that starts to emerge in mid blastocysts. We show that FGF/MAPK signalling is involved in the three-dimensional distribution of the cells and, using a mutant background, we further show that the GATA6 neighbourhood is regulated by NANOG. Our quantitative study suggests that the three-dimensional cell neighbourhood plays a role in Epi and PrE precursor specification. Our results highlight the importance of analysing the three-dimensional cell neighbourhood while investigating cell fate decisions during early mouse embryonic development.
在哺乳动物囊胚发育过程中，内细胞团（ICM）细胞分化为上胚层（Epi）或原始内胚层（PrE）。这两种命运分别由转录因子 NANOG 和 GATA6 的表达来特征化。在这里，我们通过定量的三维单细胞邻居分析，研究了小鼠囊胚 ICM 中 NANOG 和 GATA6 表达细胞的时空分布。我们通过局部特征来定义细胞邻居，这些特征包括每个细胞及其邻居表达的两个命运标记物的表达水平，以及相邻细胞的数量。我们进一步将细胞相对于 ICM 中心的位置作为全局位置特征包括在内。我们的分析揭示了早期囊胚中已经存在的局部三维模式：1）表达最高 NANOG 水平的细胞被大约九个邻居包围，而 2）表达 GATA6 的细胞根据其 GATA6 水平聚类。这种局部模式在中囊胚开始出现时演变成 ICM 中的全局模式。我们表明 FGF/MAPK 信号通路参与了细胞的三维分布，并且使用突变背景，我们进一步表明 GATA6 邻居受 NANOG 调控。我们的定量研究表明，三维细胞邻居在 Epi 和 PrE 前体特化中起作用。我们的结果强调了在研究早期小鼠胚胎发育过程中的细胞命运决定时，分析三维细胞邻居的重要性。
