Montembault Emilie, Claverie Marie-Charlotte, Bouit Lou, Landmann Cedric, Jenkins James, Tsankova Anna, Cabernard Clemens, Royou Anne
University of Bordeaux, CNRS, UMR5095, Institut Européen de Chimie et Biologie, 2 Rue Robert Escarpit, Pessac, 33607, France.
Department of Biology, University of Washington, Seattle, WA, 98195, USA.
Nat Commun. 2017 Aug 23;8(1):326. doi: 10.1038/s41467-017-00337-6.
Chromatid segregation must be coordinated with cytokinesis to preserve genomic stability. Here we report that cells clear trailing chromatids from the cleavage site by undergoing two phases of cell elongation. The first phase relies on the assembly of a wide contractile ring. The second phase requires the activity of a pool of myosin that flows from the ring and enriches the nascent daughter cell cortices. This myosin efflux is a novel feature of cytokinesis and its duration is coupled to nuclear envelope reassembly and the nuclear sequestration of the Rho-GEF Pebble. Trailing chromatids induce a delay in nuclear envelope reassembly concomitant with prolonged cortical myosin activity, thus providing forces for the second elongation. We propose that the modulation of cortical myosin dynamics is part of the cellular response triggered by a "chromatid separation checkpoint" that delays nuclear envelope reassembly and, consequently, Pebble nuclear sequestration when trailing chromatids are present at the midzone.Chromatid segregation must be coordinated with cytokinesis to preserve genomic stability. Here the authors show that cells clear trailing chromatids from the cleavage site in a two-step cell elongation and demonstrate the role of myosin efflux in the second phase.
染色单体分离必须与胞质分裂协调进行，以维持基因组稳定性。在此，我们报告细胞通过经历两个细胞伸长阶段，从分裂位点清除滞后染色单体。第一阶段依赖于一个宽阔收缩环的组装。第二阶段需要一群肌球蛋白的活性，这群肌球蛋白从环处流出并富集于新生子细胞的皮质。这种肌球蛋白外流是胞质分裂的一个新特征，其持续时间与核膜重新组装以及Rho鸟嘌呤核苷酸交换因子（Rho-GEF）“鹅卵石”（Pebble）的核隔离相关联。滞后染色单体导致核膜重新组装延迟，并伴有皮质肌球蛋白活性延长，从而为第二次伸长提供动力。我们提出，皮质肌球蛋白动力学的调节是由“染色单体分离检查点”触发的细胞反应的一部分，当滞后染色单体出现在中区时，该检查点会延迟核膜重新组装，进而延迟“鹅卵石”的核隔离。染色单体分离必须与胞质分裂协调进行，以维持基因组稳定性。在此，作者表明细胞通过两步细胞伸长从分裂位点清除滞后染色单体，并证明了肌球蛋白外流在第二阶段中的作用。
