Venus trap in the mouse embryo reveals distinct molecular dynamics underlying specification of first embryonic lineages
Venus trap in the mouse embryo reveals distinct molecular dynamics underlying specification of first embryonic lineages
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DOI：
10.15252/embr.201540162
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发表时间：
2015-08-01
期刊：
影响因子：
7.7
通讯作者：
Hiiragi, Takashi
中科院分区：
文献类型：
--
作者：
Dietrich, Jens-Erik;Panavaite, Laura;Hiiragi, Takashi
哺乳动物的发育始于胚泡中胚胎和胚外谱系的分离。最近的研究揭示了小鼠囊胚形成过程中细胞间基因表达的异质性和动态细胞重排。因此，谱系规范的机械理解需要在活胚胎中以单细胞分辨率定量描述基因表达动态。然而，迄今为止，只有少数荧光基因表达报告小鼠可用，并且定量活体图像分析有限。在这里，我们进行了荧光基因陷阱筛选，并建立了报告小鼠表达金星特异性在第一谱系。谱系追踪，定量基因表达和细胞位置分析使我们能够建立一个全面的谱系图小鼠植入前发育。我们的系统分析表明，与现有的模型相反，滋养外胚层和内细胞团之间的谱系特化的时间和机制可能是不同的。虽然我们的滋养外胚层特异性谱系标志物的表达在8-和16-细胞阶段的不对称分裂时在外部细胞中上调，但内部细胞质量标志物的内部特异性上调仅在64-细胞阶段变得明显。因此，这项研究提供了一个框架，对系统水平的理解，胚胎发生标记的高动态性和随机变异。
Mammalian development begins with the segregation of embryonic and extra-embryonic lineages in the blastocyst. Recent studies revealed cell-to-cell gene expression heterogeneity and dynamic cell rearrangements during mouse blastocyst formation. Thus, mechanistic understanding of lineage specification requires quantitative description of gene expression dynamics at a single-cell resolution in living embryos. However, only a few fluorescent gene expression reporter mice are available and quantitative live image analysis is limited so far. Here, we carried out a fluorescence gene-trap screen and established reporter mice expressing Venus specifically in the first lineages. Lineage tracking, quantitative gene expression and cell position analyses allowed us to build a comprehensive lineage map of mouse pre-implantation development. Our systematic analysis revealed that, contrary to the available models, the timing and mechanism of lineage specification may be distinct between the trophectoderm and the inner cell mass. While expression of our trophectoderm-specific lineage marker is upregulated in outside cells upon asymmetric divisions at 8- and 16-cell stages, the inside-specific upregulation of the inner-cell-mass marker only becomes evident at the 64-cell stage. This study thus provides a framework toward systems-level understanding of embryogenesis marked by high dynamicity and stochastic variability.