Yukawa Masashi, Teratani Yasuhiro, Toda Takashi
Hiroshima Research Center for Healthy Aging (HiHA), Hiroshima University, Higashi-Hiroshima 739-8530, Japan.
Laboratory of Molecular and Chemical Cell Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima 739-8530, Japan.
iScience. 2021 Jan 1;24(1):102031. doi: 10.1016/j.isci.2020.102031. eCollection 2021 Jan 22.
Eukaryotic cells position the nucleus within the proper intracellular space, thereby safeguarding a variety of cellular processes. In fission yeast, the interphase nucleus is placed in the cell middle in a microtubule-dependent manner. By contrast, how the mitotic nucleus is positioned remains elusive. Here we show that several cell-cycle mutants that arrest in mitosis all displace the nucleus toward one end of the cell. Intriguingly, the actin cytoskeleton is responsible for nuclear movement. Time-lapse live imaging indicates that mitosis-specific F-actin cables possibly push the nucleus through direct interaction with the nuclear envelope, and subsequently actomyosin ring constriction further shifts the nucleus away from the center. This nuclear movement is beneficial, because if the nuclei were retained in the center, unseparated chromosomes would be intersected by the contractile actin ring and the septum, imposing the lethal cut phenotype. Thus, fission yeast escapes from mitotic catastrophe by means of actin-dependent nuclear movement.
真核细胞将细胞核定位在合适的细胞内空间，从而保障各种细胞过程。在裂殖酵母中，间期细胞核以微管依赖的方式位于细胞中部。相比之下，有丝分裂细胞核的定位方式仍不清楚。在这里，我们表明，几个在有丝分裂中停滞的细胞周期突变体都会将细胞核移向细胞的一端。有趣的是，肌动蛋白细胞骨架负责细胞核的移动。延时实时成像表明，有丝分裂特异性F-肌动蛋白束可能通过与核膜的直接相互作用推动细胞核，随后肌动球蛋白环收缩进一步将细胞核从中心移开。这种细胞核移动是有益的，因为如果细胞核保留在中心，未分离的染色体将被收缩的肌动蛋白环和隔膜交叉，导致致命的切割表型。因此，裂殖酵母通过肌动蛋白依赖的细胞核移动避免有丝分裂灾难。
