Flow-dependent myosin recruitment during Drosophila cellularization requires zygotic dunk activity
Flow-dependent myosin recruitment during Drosophila cellularization requires zygotic dunk activity
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DOI：
10.1242/dev.131334
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发表时间：
2016-07-01
期刊：
影响因子：
4.6
通讯作者：
Wieschaus, Eric
中科院分区：
文献类型：
--
作者：
He, Bing;Martin, Adam;Wieschaus, Eric
肌动球蛋白收缩性是形态发生中从胞质分裂到上皮延伸或内陷的力产生的基础。在果蝇中，合胞体胚层的分裂是由从胚胎表面内陷的膜沟底部的肌动球蛋白网络启动的。目前尚不清楚该网络如何形成以及它如何影响组织力学。在这里，我们表明，在果蝇卵裂过程中，肌球蛋白向卵裂沟的募集在张力驱动的皮层流动和直接募集的时间上不同的阶段进行，受不同合子基因的调节。我们鉴定了基因 dunk，我们发现该基因在细胞化开始时短暂转录，并在流动阶段发挥维持皮质肌球蛋白的作用。然而，随后的直接肌球蛋白招募与 Dunk 无关，但需要 Slam。肌球蛋白的 Slam 依赖性直接募集足以驱动 dunk 突变体中的裂解，并且突变体的后续发育是正常的。在 dunk 突变体中，皮质肌球蛋白的丢失会引发错误的流动并破坏进入沟槽的六边形堆积。计算机模拟与激光消融相结合表明，皮质肌球蛋白的 Dunk 依赖性维持能够增强机械张力，从而提供一种引导肌球蛋白流动并定义皱纹的六边形对称性的机制。
Actomyosin contractility underlies force generation in morphogenesis ranging from cytokinesis to epithelial extension or invagination. In Drosophila, the cleavage of the syncytial blastoderm is initiated by an actomyosin network at the base of membrane furrows that invaginate from the surface of the embryo. It remains unclear how this network forms and how it affects tissue mechanics. Here, we show that during Drosophila cleavage, myosin recruitment to the cleavage furrows proceeds in temporally distinct phases of tension-driven cortical flow and direct recruitment, regulated by different zygotic genes. We identify the gene dunk, which we show is transiently transcribed when cellularization starts and functions to maintain cortical myosin during the flow phase. The subsequent direct myosin recruitment, however, is Dunk-independent but requires Slam. The Slam-dependent direct recruitment of myosin is sufficient to drive cleavage in the dunk mutant, and the subsequent development of the mutant is normal. In the dunk mutant, cortical myosin loss triggers misdirected flow and disrupts the hexagonal packing of the ingressing furrows. Computer simulation coupled with laser ablation suggests that Dunk-dependent maintenance of cortical myosin enables mechanical tension build-up, thereby providing a mechanism to guide myosin flow and define the hexagonal symmetry of the furrows.