Cramer L P, Mitchison T J
Department of Cellular and Molecular Pharmacology, University of California, San Francisco 94143-0450, USA.
Mol Biol Cell. 1997 Jan;8(1):109-19. doi: 10.1091/mbc.8.1.109.
We have studied two types of cell motility directed toward the cell center: retraction of the cell margin and rearward flow of small cytoplasmic nodules during mitotic cell rounding in Potoroo tridactylis kidney (PtK2) cells by time-lapse video microscopy, drug treatments, and photoactivation of fluorescence. Nodules flow rearward on thin, actin-rich fibers (retraction fibers) exposed as the cell margin retracts. Retraction of the cell margin and rearward flow of nodules require intact actin filaments, but are insensitive to an inhibitor of myosin function (butanedione monoxime). Using photoactivation of fluorescence marking, we have determined that actin filaments in the majority of retraction fibers remain stationary while the cell margin retracts and nodules flow rearward. The pointed ends of retraction fiber actin filaments face the cell center. We argue that nodule motility is driven by a novel actin-based force that perhaps also partially contributes to retraction of the cell margin during cell rounding at mitosis.
我们通过延时视频显微镜、药物处理和荧光光激活技术，研究了袋鼠肾（PtK2）细胞有丝分裂细胞变圆过程中两种朝向细胞中心的细胞运动类型：细胞边缘的回缩以及小细胞质结节的向后流动。随着细胞边缘回缩，结节在暴露的富含肌动蛋白的细纤维（回缩纤维）上向后流动。细胞边缘的回缩和结节的向后流动需要完整的肌动蛋白丝，但对肌球蛋白功能抑制剂（丁二酮单肟）不敏感。利用荧光标记的光激活技术，我们确定在细胞边缘回缩和结节向后流动时，大多数回缩纤维中的肌动蛋白丝保持静止。回缩纤维肌动蛋白丝的尖端朝向细胞中心。我们认为，结节运动是由一种基于肌动蛋白的新力量驱动的，这种力量可能在有丝分裂细胞变圆过程中也部分促成了细胞边缘的回缩。
