Tbx16 and Msgn1 are required to establish directional cell migration of zebrafish mesodermal progenitors.
Tbx16 and Msgn1 are required to establish directional cell migration of zebrafish mesodermal progenitors.
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DOI：
10.1016/j.ydbio.2015.09.001
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发表时间：
2015-10-15
影响因子：
2.7
通讯作者：
Kimelman D
中科院分区：
文献类型：
--
作者：
Manning AJ;Kimelman D
上皮向间充质转化(EMT)是胚胎发育过程中反复发生的一个重要过程，稳定的贴壁细胞通过该过程转化为活跃的迁移状态。虽然人们对启动EMT的因素和事件知道得很多，但对细胞进行定向迁移所经历的步骤还知之甚少。斑马鱼胚胎缺乏转录因子Tbx16/SpaDetail和Mesgenin1(Msgn1)，是研究EMT的有价值的系统。这些胚胎中的中胚层细胞不能进行必要的EMT，以离开身体的最后端(尾芽)并加入体节前中胚层，这一过程在所有脊椎动物中都是保守的。以前在脊椎动物中研究这种EMT非常困难，因为尾芽中有多种细胞类型，而且整个胚胎都经历了形态发生的变化。在这里，我们描述了一种新的组织外植体系统，用于在体内对中胚层细胞EMT进行成像，使我们能够以高时空分辨率研究在EMT过程中细胞获得迁移属性的要求。这种方法显示，尽管tbx16；msgn1缺陷的细胞不能离开尾芽，但令人惊讶的是，这些细胞中基于肌动蛋白的突起形成得很正常，它们变得非常能动。然而，tbx16；msgn1缺陷细胞在迁徙的持续性和前向性上有特殊的细胞自主性缺陷，因为它们形成的片状脂膜不能有效地驱动向前迁移。此外，我们发现中胚层的形态发生和分化是可分离的，并且存在一个独立于Tbx16和Msgn1的指导中胚层细胞迁移的迁移线索。这项工作定义了细胞在完成EMT时所经历的变化，并为体内细胞成为间充质所需的机制提供了新的见解。
The epithelial to mesenchymal transition (EMT) is an essential process that occurs repeatedly during embryogenesis whereby stably adherent cells convert to an actively migrating state. While much is known about the factors and events that initiate the EMT, the steps that cells undergo to become directionally migratory are far less well understood. Zebrafish embryos lacking the transcription factors Tbx16/Spadetail and Mesogenin1 (Msgn1) are a valuable system for investigating the EMT. Mesodermal cells in these embryos are unable to perform the EMT necessary to leave the most posterior end of the body (the tailbud) and join the pre-somitic mesoderm, a process that is conserved in all vertebrates. It has previously been very difficult to study this EMT in vertebrates because of the multiple cell types in the tailbud and the morphogenetic changes the whole embryo undergoes. Here, we describe a novel tissue explant system for imaging the mesodermal cell EMT in vivo that allows us to investigate the requirements for cells to acquire migratory properties during the EMT with high spatio-temporal resolution. This method revealed that, despite the inability of tbx16;msgn1-deficient cells to leave the tailbud, actin-based protrusions form surprisingly normally in these cells and they become highly motile. However, tbx16;msgn1-deficient cells have specific cell-autonomous defects in the persistence and anterior direction of migration because the lamellipodia they form are not productive in driving anteriorward migration. Additionally, we show that mesoderm morphogenesis and differentiation are separable and that there is a migratory cue that directs mesodermal cell migration that is independent of Tbx16 and Msgn1. This work defines changes that cells undergo as they complete the EMT and provides new insight into the mechanisms required in vivo for cells to become mesenchymal.