Uchida Kazuhiko S K, Kitanishi-Yumura Toshiko, Yumura Shigehiko
Department of Biology, Faculty of Science, Yamaguchi University, Yamaguchi 753-8512, Japan.
J Cell Sci. 2003 Jan 1;116(Pt 1):51-60. doi: 10.1242/jcs.00195.
Cells must exert force against the substrate to migrate. We examined the vectors (both the direction and the magnitude) of the traction force generated by Dictyostelium cells using an improved non-wrinkling silicone substrate. During migration, the cells showed two 'alternate' phases of locomotory behavior, an extension phase and a retraction phase. In accordance with these phases, two alternate patterns were identified in the traction force. During the extension phase, the cell exerted a 'pulling force' toward the cell body in the anterior and the posterior regions and a 'pushing force' in the side of the cell (pattern 1). During the retraction phase, the cell exerted a 'pushing force' in the anterior region, although the force disappeared in the side and the posterior regions of the cell (pattern 2). Myosin II heavy chain null cells showed a single pattern in their traction force comparable to 'pattern 1', although they still had the alternate biphasic locomotory behavior similar to the wild-type cells. Therefore, the generation of 'pushing force' in the anterior and the cancellation of the traction force in the side and the posterior during the retraction phase were deficient in myosin knock-out mutant cells, suggesting that these activities depend on myosin II via the posterior contraction. Considering all these results, we hypothesized that there is a highly coordinated, biphasic mechanism of cell migration in Dictyostelium.
细胞迁移时必须对底物施加力。我们使用一种改进的无褶皱硅酮底物，研究了盘基网柄菌细胞产生的牵引力的矢量（包括方向和大小）。在迁移过程中，细胞表现出两个“交替”的运动行为阶段，即伸展阶段和收缩阶段。与这些阶段一致，在牵引力中识别出两种交替模式。在伸展阶段，细胞在前后区域向细胞体施加“拉力”，在细胞侧面施加“推力”（模式1）。在收缩阶段，细胞在前部区域施加“推力”，尽管该力在细胞的侧面和后部区域消失（模式2）。肌球蛋白II重链缺失细胞在其牵引力中表现出与“模式1”相当的单一模式，尽管它们仍然具有与野生型细胞相似的交替双相运动行为。因此，在收缩阶段，肌球蛋白基因敲除突变细胞在前部产生“推力”以及在侧面和后部消除牵引力的能力存在缺陷，这表明这些活动通过后部收缩依赖于肌球蛋白II。综合所有这些结果，我们推测盘基网柄菌中存在一种高度协调的双相细胞迁移机制。
