Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada.
Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada.
Mol Biol Cell. 2018 Feb 15;29(4):419-434. doi: 10.1091/mbc.E17-05-0294. Epub 2017 Dec 27.
An intact actomyosin network is essential for anchoring polarity proteins to the cell cortex and maintaining cell size asymmetry during asymmetric cell division of neuroblasts (NBs). However, the mechanisms that control changes in actomyosin dynamics during asymmetric cell division remain unclear. We find that the actin-binding protein, Moesin, is essential for NB proliferation and mitotic progression in the developing brain. During metaphase, phosphorylated Moesin (p-Moesin) is enriched at the apical cortex, and loss of Moesin leads to defects in apical polarity maintenance and cortical stability. This asymmetric distribution of p-Moesin is determined by components of the apical polarity complex and Slik kinase. During later stages of mitosis, p-Moesin localization shifts more basally, contributing to asymmetric cortical extension and myosin basal furrow positioning. Our findings reveal Moesin as a novel apical polarity protein that drives cortical remodeling of dividing NBs, which is essential for polarity maintenance and initial establishment of cell size asymmetry.
一个完整的肌动球蛋白网络对于锚定极性蛋白到细胞皮层和维持神经母细胞（NB）不对称细胞分裂期间的细胞大小不对称是必不可少的。然而，控制肌动球蛋白动力学在不对称细胞分裂过程中变化的机制尚不清楚。我们发现肌动蛋白结合蛋白 Moesin 对于大脑发育过程中 NB 的增殖和有丝分裂进展是必需的。在中期，磷酸化的 Moesin（p-Moesin）在顶端皮层富集，Moesin 的缺失导致顶端极性的维持和皮层稳定性的缺陷。这种 p-Moesin 的不对称分布是由顶端极性复合物和 Slik 激酶的成分决定的。在有丝分裂的后期，p-Moesin 的定位更向基底转移，有助于不对称的皮层延伸和肌球蛋白基底沟的定位。我们的发现揭示了 Moesin 作为一种新的顶端极性蛋白，驱动分裂 NB 的皮层重塑，这对于极性的维持和细胞大小不对称的初始建立是必不可少的。
