Ezrin becomes restricted to outer cells following asymmetrical division in the preimplantation mouse embryo
Ezrin becomes restricted to outer cells following asymmetrical division in the preimplantation mouse embryo
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DOI：
10.1006/dbio.1996.0186
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发表时间：
1996-08-01
影响因子：
2.7
通讯作者：
Maro, B
中科院分区：
文献类型：
--
作者：
Louvet, S;Aghion, J;Maro, B
在小鼠着床前发育过程中，两个表型不同的细胞群出现在16细胞阶段：非极化的内细胞，产生内细胞团和极化的外细胞，主要产生滋养外胚层。这两种细胞谱系的分歧是由于在卵裂球极化后可能发生的从8细胞阶段到16细胞阶段的过渡期间的不对称细胞分裂。在致密化过程中，在8-细胞阶段，细胞质细胞器聚集在顶端区域，形成微绒毛的表面极，并且卵裂球彼此扁平。在8- 16-细胞期的分裂过程中，只有微绒毛极保持着不对称的结构。在16-细胞期，只有继承了大部分微绒毛极结构的卵裂球才能重建极化组织。微绒毛顶极的形成和稳定机制尚不清楚。Ezrin是一种肌动蛋白相关蛋白，已被提出在微绒毛结构的形成中发挥作用。这导致我们研究ezrin在小鼠胚胎早期发育过程中的表达。我们观察到埃兹蛋白mRNA和蛋白质存在于小鼠卵母细胞和整个植入前胚胎发育过程中，尽管蛋白质的存在量在早期发育过程中不断减少，特别是在8细胞阶段之后，在压实时。两种异构体的ezrin磷酸化的酪氨酸残基是存在于所有的植入前发育，而第三个非酪氨酸磷酸化的异构体出现在8细胞阶段，其相对量增加，从8细胞阶段的囊胚阶段。在压实之前，埃兹蛋白分布在细胞皮层周围。然而，埃兹林成为限制在微绒毛的顶极压实后。在后期，埃兹蛋白存在于外细胞顶面的微绒毛中。最后，ezrin在从8-到16-细胞阶段的过渡期间保持与微绒毛极结合，并且仅在分裂后的外部细胞中发现。因此，埃兹蛋白是第一个描述的细胞皮质蛋白，在不对称分裂后的16细胞阶段完全分离在外细胞中。(C)出版社：Academic Press，Inc.
During preimplantation development in the mouse, two phenotypically distinct cell populations appear at the 16-cell stage: nonpolarized inner cells that give rise to the inner cell mass and polarized outer cells that give rise mainly to the trophectoderm. The divergence of these two cell lineages is due to asymmetrical cell divisions during the transition from the 8- to the 16 cell stage which can occur following blastomere polarization. During compaction, at the 8-cell stage, cytoplasmic organelles accumulate in the apical domain, a surface pole of microvilli forms, and blastomeres flatten onto one another. During the division from the 8- to the 16-cell stage, the only asymmetrical structure maintained is the pole of microvilli, At the 16-cell stage, only blastomeres inheriting a large part of this apical structure can reestablish a polarized organization. The mechanisms involved in the formation and stabilization of the apical pole of microvilli are still unknown. Ezrin is an actin-associated protein that has been proposed to play a role in the formation of microvillous structures. This led us to study the expression of ezrin during early development of the mouse embryo. We observed that ezrin mRNA and protein are present in the mouse oocyte and throughout preimplantation embryo development, although the amount of protein present decreases continuously during early development, particularly after the 8-cell stage, at the time of compaction. Two isoforms of ezrin phosphorylated on tyrosine residues are present during all of preimplantation development while a third non-tyrosine-phosphorylated isoform appears at the 8-cell stage and its relative amount increases from the 8-cell stage to the blastocyst stage. Before compaction, ezrin is distributed around the cell cortex. However ezrin becomes restricted to the microvilli of the apical pole after compaction. At later stages, ezrin is found in the microvilli of the apical surface of outer cells. finally, ezrin remains associated with the microvillous pole during the transition from the 8- to 16-cell stage and is found only in the outer cells after division. Thus, ezrin is the first cytocortical protein described that is totally segregated in outer cells at the 16-cell stage after an asymmetrical division. (C) 1996 Academic Press, Inc.