Interface extension is a continuum property suggesting a linkage between AP contractile and DV lengthening processes.
Interface extension is a continuum property suggesting a linkage between AP contractile and DV lengthening processes.
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DOI：
10.1091/mbc.e21-07-0352
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发表时间：
2022-12-01
影响因子：
3.3
通讯作者：
Loerke, Dinah
中科院分区：
文献类型：
--
作者：
Vanderleest, Timothy E.;Xie, Yi;Smits, Celia;Blankenship, J. Todd;Loerke, Dinah
在果蝇早期胚胎中，前-后(AP)体轴的延长是由生殖带上皮中的细胞嵌入所驱动的。相邻细胞通过收缩AP接口(AP邻居之间)进入更高阶顶点，然后通过延伸新的背腹(DV)接口(DV邻居之间)来分解。尽管界面收缩已被广泛研究，但人们对新界面是如何建立的知之甚少。在这里，我们表明DV界面的伸长行为与AP收缩同时开始，并且从更高阶顶点的分辨率新创建的DV界面似乎并不具有唯一的“身份”；相反，所有的水平界面都经历了延长，通过类似于AP界面中发现的棘轮状滑动行为来伸长。皮质F-肌动蛋白网络对于有效棘轮活动所需的高区域振荡幅度是必不可少的。我们的结果表明，与正则模型相反，新DV界面的伸长不是由机械分离过程产生的。相反，内侧肌球蛋白群体驱动细胞内振荡的径向力，在所有三细胞顶点产生瞬变力不对称，与平面极化稳定相结合，产生定向棘轮滑动，从而产生AP界面收缩和DV界面延长。
In the early Drosophila embryo, the elongation of the anterior-posterior (AP) body axis is driven by cell intercalation in the germband epithelium. Neighboring cells intercalate through the contraction of AP interfaces (between AP neighbors) into higher-order vertices, which then resolve through the extension of new dorsal-ventral (DV) interfaces (between DV neighbors). Although interface contraction has been extensively studied, less is known about how new interfaces are established. Here we show that DV interface elongation behaviors initiate at the same time as AP contractions, and that DV interfaces which are newly created from resolution of higher-order vertices do not appear to possess a unique ‘identity;’ instead, all horizontal interfaces undergo lengthening, elongating through ratchetlike sliding behaviors analogous to those found in AP interfaces. Cortical F-actin networks are essential for high area oscillation amplitudes required for effective ratcheting. Our results suggest that, contrary to canonical models, the elongation of new DV interfaces is not produced by a mechanistically separate process. Instead, medial myosin populations drive oscillating radial forces in the cells to generate transient force asymmetries at all tricellular vertices, which—combined with planar polarized stabilization—produce directional ratcheted sliding to generate both AP interface contraction and DV interface elongation.