Reassessing the role and dynamics of nonmuscle myosin II during furrow formation in early Drosophila embryos
Reassessing the role and dynamics of nonmuscle myosin II during furrow formation in early Drosophila embryos
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DOI：
10.1091/mbc.e03-06-0440
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发表时间：
2004-02-01
影响因子：
3.3
通讯作者：
Karess, R
中科院分区：
文献类型：
--
作者：
Royou, A;Field, C;Karess, R
早期果蝇胚胎经历了两个不同的膜内陷事件，被认为是机械相关的胞质分裂：中期沟形成和细胞化。两者都涉及肌动蛋白细胞骨架重排，都有肌球蛋白II或附近的形成沟。肌动蛋白和肌球蛋白被认为提供了驱动膜内陷的力量;然而，膜的添加也很重要。我们已经研究了肌球蛋白在活胚胎中这些事件中的作用，具有全功能的肌球蛋白调节轻链-GFP嵌合体。我们发现，沟内陷在中期和细胞化发生，即使肌球蛋白活性已被实验扰动。相反，细胞化沟的基底闭合和细胞化后的第一次胞质分裂高度依赖于肌球蛋白。引人注目的是，当细胞化犁沟的侵入被秋水仙素处理实验抑制时，基底闭合仍然在适当的时间发生，这表明它独立于早期细胞化事件而被调节。我们还确定了一个以前未被认识的水库颗粒肌球蛋白，是招募到内陷沟的基底在一个微生物不依赖和微管依赖的方式。我们认为，细胞化可以分为两个不同的过程：沟内陷，驱动微管介导的囊泡交付，和基底关闭，这是由肌动蛋白/肌球蛋白为基础的收缩介导。
The early Drosophila embryo undergoes two distinct membrane invagination events believed to be mechanistically related to cytokinesis: metaphase furrow formation and cellularization. Both involve actin cytoskeleton rearrangements, and both have myosin II at or near the forming furrow. Actin and myosin are thought to provide the force driving membrane invagination; however, membrane addition is also important. We have examined the role of myosin during these events in living embryos, with a fully functional myosin regulatory light-chain-GFP chimera. We find that furrow invagination during metaphase and cellularization occurs even when myosin activity has been experimentally perturbed. In contrast, the basal closure of the cellularization furrows and the first cytokinesis after cellularization are highly dependent on myosin. Strikingly, when ingression of the cellularization furrow is experimentally inhibited by colchicine treatment, basal closure still occurs at the appropriate time, suggesting that it is regulated independently of earlier cellularization events. We have also identified a previously unrecognized reservoir of particulate myosin that is recruited basally into the invaginating furrow in a microfilament-independent and microtubule-dependent manner. We suggest that cellularization can be divided into two distinct processes: furrow ingression, driven by microtubule mediated vesicle delivery, and basal closure, which is mediated by actin/myosin based constriction.