Institute of Science and Technology Austria, Am Campus 1, A-3400 Klosterneuburg, Austria.
Nat Cell Biol. 2013 Dec;15(12):1405-14. doi: 10.1038/ncb2869. Epub 2013 Nov 10.
Epithelial spreading is a common and fundamental aspect of various developmental and disease-related processes such as epithelial closure and wound healing. A key challenge for epithelial tissues undergoing spreading is to increase their surface area without disrupting epithelial integrity. Here we show that orienting cell divisions by tension constitutes an efficient mechanism by which the enveloping cell layer (EVL) releases anisotropic tension while undergoing spreading during zebrafish epiboly. The control of EVL cell-division orientation by tension involves cell elongation and requires myosin II activity to align the mitotic spindle with the main tension axis. We also found that in the absence of tension-oriented cell divisions and in the presence of increased tissue tension, EVL cells undergo ectopic fusions, suggesting that the reduction of tension anisotropy by oriented cell divisions is required to prevent EVL cells from fusing. We conclude that cell-division orientation by tension constitutes a key mechanism for limiting tension anisotropy and thus promoting tissue spreading during EVL epiboly.
上皮细胞铺展是各种发育和疾病相关过程（如上皮细胞闭合和伤口愈合）的常见和基本方面。正在进行铺展的上皮组织面临的一个关键挑战是在不破坏上皮完整性的情况下增加其表面积。在这里，我们表明通过张力定向细胞分裂是一种有效的机制，通过该机制，在斑马鱼胚外包裹过程中，包裹细胞层（EVL）在进行铺展的同时释放各向异性张力。张力对 EVL 细胞分裂方向的控制涉及细胞伸长，并需要肌球蛋白 II 活性使有丝分裂纺锤体与主要张力轴对齐。我们还发现，在不存在张力定向细胞分裂的情况下和在组织张力增加的情况下，EVL 细胞发生异位融合，这表明通过定向细胞分裂减少张力各向异性对于防止 EVL 细胞融合是必需的。我们得出结论，张力定向细胞分裂是限制张力各向异性并因此促进 EVL 胚外包裹过程中组织铺展的关键机制。
