Asymmetric cortical extension shifts cleavage furrow position in Drosophila neuroblasts.
Asymmetric cortical extension shifts cleavage furrow position in Drosophila neuroblasts.
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DOI：
10.1091/mbc.e11-02-0173
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发表时间：
2011-11
影响因子：
3.3
通讯作者：
Prehoda KE
中科院分区：
文献类型：
--
作者：
Connell M;Cabernard C;Ricketson D;Doe CQ;Prehoda KE
在果蝇神经母细胞不对称分裂的后期，一个不依赖于纺锤体的含有肌球蛋白II的结构域会导致不对称的皮质伸展。异三聚体G蛋白调节肌球蛋白II结构域的活性，它们的缺失导致对称性扩张和子细胞大小。细胞分裂沟通常相对于皮质细胞边界对称，但也可以是不对称的。控制沟槽位置的机制已经得到了深入的研究，但极地皮质运动如何影响最终的沟槽位置仍然知之甚少。我们测量了果蝇神经母细胞不对称分裂的顶叶和基底层皮质的位置，观察到在果蝇神经母细胞分裂后期，顶叶皮质优先移位，成为较大的子细胞，有效地将分裂沟向较小的子细胞移动。不对称的皮质延伸与皮质肌球蛋白II的存在有关，而皮质肌球蛋白II在神经母细胞中被极化。通过干扰异源三聚体G蛋白信号导致肌球蛋白II不对称性的丧失，导致对称伸展和大小相等的子细胞。我们提出了一个模型，在这个模型中，后期神经母细胞皮质的收缩驱动的不对称极性延伸有助于不对称的沟槽位置和子细胞大小。
A spindle-independent, myosin II–containing domain causes asymmetric cortical extension during anaphase of asymmetrically dividing Drosophila neuroblasts. Heterotrimeric G-proteins regulate the activity of the myosin II domain, and their loss leads to symmetric expansion and daughter cell size. The cytokinetic cleavage furrow is typically positioned symmetrically relative to the cortical cell boundaries, but it can also be asymmetric. The mechanisms that control furrow site specification have been intensively studied, but how polar cortex movements influence ultimate furrow position remains poorly understood. We measured the position of the apical and the basal cortex in asymmetrically dividing Drosophila neuroblasts and observed preferential displacement of the apical cortex that becomes the larger daughter cell during anaphase, effectively shifting the cleavage furrow toward the smaller daughter cell. Asymmetric cortical extension is correlated with the presence of cortical myosin II, which is polarized in neuroblasts. Loss of myosin II asymmetry by perturbing heterotrimeric G-protein signaling results in symmetric extension and equal-sized daughter cells. We propose a model in which contraction-driven asymmetric polar extension of the neuroblast cortex during anaphase contributes to asymmetric furrow position and daughter cell size.