Mechanisms of cell positioning during C-elegans gastrulation
Mechanisms of cell positioning during C-elegans gastrulation
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DOI：
10.1242/dev.00211
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发表时间：
2003-01-01
期刊：
影响因子：
4.6
通讯作者：
Goldstein, B
中科院分区：
文献类型：
--
作者：
Lee, JY;Goldstein, B
细胞重排在发育过程中至关重要。在本研究中，我们使用线虫原肠胚形成作为简单模型来研究细胞定位的机制。在秀丽隐杆线虫原肠胚形成过程中，两个内胚层前体细胞从腹侧表面移动到胚胎的中心，在这些进入的细胞和蛋壳之间留下间隙。六个相邻的细胞聚集在内胚层前体下方，填补了这个空白。使用体外系统，我们观察到这些运动在没有蛋壳和卵黄包膜的情况下一致发生。我们发现相邻细胞之间的运动并不依赖于这些细胞之间的趋化信号传导。我们进一步发现线虫原肠胚形成需要完整的微丝，但不需要微管。基于微丝的运动的主要机制似乎并不是通过突出的结构，例如板状伪足或丝状伪足。相反，我们的结果提出了一种替代机制。我们发现原肠胚形成需要肌球蛋白活性，进入细胞的顶端收缩，并且进入细胞决定其邻近细胞的运动方向。基于这些结果，我们提出进入是由进入细胞顶端侧基于肌动球蛋白的收缩驱动的，它将邻近的细胞拉到下面。我们得出的结论是，即使在细胞之间形成锚定连接之前，顶端收缩也可以在早期胚胎中定位卵裂球。
Cell rearrangements are crucial during development. In this study, we use C. elegans gastrulation as a simple model to investigate the mechanisms of cell positioning. During C. elegans gastrulation, two endodermal precursor cells move from the ventral surface to the center of the embryo, leaving a gap between these ingressing cells and the eggshell. Six neighboring cells converge under the endodermal precursors, filling this gap. Using an in vitro system, we observed that these movements occurred consistently in the absence of the eggshell and the vitelline envelope. We found that movement of the neighbors towards each other is not dependent on chemotactic signaling between these cells. We further found that C. elegans gastrulation requires intact microfilaments, but not microtubules. The primary mechanism of microfilament-based motility does not appear to be through protrusive structures, such as lamellipodia or filopodia. Instead, our results suggest an alternative mechanism. We found that myosin activity is required for gastrulation, that the apical sides of the ingressing cells contract, and that the ingressing cells determine the direction of movement of their neighboring cells. Based on these results, we propose that ingression is driven by an actomyosin-based contraction of the apical side of the ingressing cells, which pulls neighboring cells underneath. We conclude that apical constriction can function to position blastomeres in early embryos, even before anchoring junctions form between cells.