Institute of Molecular Biology, Department of Chemistry and Biochemistry, University of Oregon, Eugene, United States.
Elife. 2021 Nov 15;10:e66574. doi: 10.7554/eLife.66574.
The Par complex dynamically polarizes to the apical cortex of asymmetrically dividing neuroblasts where it directs fate determinant segregation. Previously, we showed that apically directed cortical movements that polarize the Par complex require F-actin (Oon and Prehoda, 2019). Here, we report the discovery of cortical actomyosin dynamics that begin in interphase when the Par complex is cytoplasmic but ultimately become tightly coupled to cortical Par dynamics. Interphase cortical actomyosin dynamics are unoriented and pulsatile but rapidly become sustained and apically-directed in early mitosis when the Par protein aPKC accumulates on the cortex. Apical actomyosin flows drive the coalescence of aPKC into an apical cap that depolarizes in anaphase when the flow reverses direction. Together with the previously characterized role of anaphase flows in specifying daughter cell size asymmetry, our results indicate that multiple phases of cortical actomyosin dynamics regulate asymmetric cell division.
Par 复合物动态极化到不对称分裂的神经母细胞的顶端皮层，在那里它指导命运决定因素的分离。此前，我们表明，极化 Par 复合物的顶端定向皮质运动需要 F- 肌动蛋白（Oon 和 Prehoda，2019）。在这里，我们报告了皮质肌动球蛋白动力学的发现，这些动力学始于有丝分裂前期，此时 Par 复合物位于细胞质中，但最终与皮质 Par 动力学紧密耦合。有丝分裂前期的皮质肌动球蛋白动力学是无定向和脉冲式的，但在 Par 蛋白 aPKC 积累在皮质上时，早期有丝分裂时迅速持续并向顶端定向。顶端肌动球蛋白流驱动 aPKC 聚合并形成一个顶端帽，在后期反转方向时去极化。与以前描述的后期流在指定子细胞大小不对称方面的作用一起，我们的结果表明，皮质肌动球蛋白动力学的多个阶段调节不对称细胞分裂。
