Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan.
Dev Growth Differ. 2011 Apr;53(3):366-77. doi: 10.1111/j.1440-169X.2010.01244.x.
During axis formation in amniotes, posterior and lateral epiblast cells in the area pellucida undergo a counter-rotating movement along the midline to form primitive streak (Polonaise movements). Using chick blastoderms, we investigated the signaling involved in this cellular movement in epithelial-epiblast. In cultured posterior blastoderm explants from stage X to XI embryos, either Lefty1 or Cerberus-S inhibited initial migration of the explants on chamber slides. In vivo analysis showed that inhibition of Nodal signaling by Lefty1 affected the movement of DiI-marked epiblast cells prior to the formation of primitive streak. In Lefty1-treated embryos without a primitive streak, Brachyury expression showed a patchy distribution. However, SU5402 did not affect the movement of DiI-marked epiblast cells. Multi-cellular rosette, which is thought to be involved in epithelial morphogenesis, was found predominantly in the posterior half of the epiblast, and Lefty1 inhibited the formation of rosettes. Three-dimensional reconstruction showed two types of rosette, one with a protruding cell, the other with a ventral hollow. Our results suggest that Nodal signaling may have a pivotal role in the morphogenetic movements of epithelial epiblast including Polonaise movements and formation of multi-cellular rosette.
在羊膜动物的中轴线形成过程中，明区的背部和侧部外胚层细胞沿着中轴线进行反向旋转运动，形成原始条带（波兰式运动）。使用鸡胚外胚层，我们研究了上皮-外胚层中涉及这种细胞运动的信号转导。在来自 X 期到 XI 期胚胎的培养的后部胚外层外植体中，Lefty1 或 Cerberus-S 抑制了腔室载玻片上外植体的初始迁移。体内分析表明，Lefty1 抑制 Nodal 信号转导会影响原始条带形成之前 DiI 标记的外胚层细胞的运动。在没有原始条带的 Lefty1 处理的胚胎中，Brachyury 表达显示出斑片状分布。然而，SU5402 不会影响 DiI 标记的外胚层细胞的运动。多细胞玫瑰花结，被认为参与上皮形态发生，主要存在于外胚层的后半部分，Lefty1 抑制了玫瑰花结的形成。三维重建显示出两种类型的玫瑰花结，一种具有突出的细胞，另一种具有腹侧空洞。我们的结果表明，Nodal 信号转导可能在包括波兰式运动和多细胞玫瑰花结形成在内的上皮外胚层的形态发生运动中具有关键作用。
