Bringmann Henrik, Hyman Anthony A
Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauer Strasse 108, 01307 Dresden, Germany.
Nature. 2005 Aug 4;436(7051):731-4. doi: 10.1038/nature03823.
The position of the cytokinesis furrow in a cell determines the relative sizes of its two daughter cells as well as the distribution of their contents. In animal cells, the position of the cytokinesis furrow is specified by the position of the mitotic spindle. The cytokinesis furrow bisects the spindle midway between the microtubule asters, at the site of the microtubule-based midzone, producing two daughter cells. Experiments in some cell types have suggested that the midzone positions the furrow, but experiments in other cells have suggested that the asters position the furrow. One possibility is that different organisms and cell types use different mechanisms to position the cytokinesis furrow. An alternative possibility is that both asters and the midzone contribute to furrow positioning. Recent work in C. elegans has suggested that centrosome separation and the midzone are implicated in cytokinesis. Here we examine the relative contributions of different parts of the mitotic spindle to positioning of the cytokinesis furrow in the C. elegans zygote. By spatially separating the spindle midzone from one of the asters using an ultraviolet laser, we show that the cytokinesis furrow is first positioned by a signal determined by microtubule asters, and then by a second signal that is derived from the spindle midzone. Thus, the position of the cytokinesis furrow is specified by two consecutive furrowing activities.
细胞中胞质分裂沟的位置决定了其两个子细胞的相对大小以及它们内容物的分布。在动物细胞中，胞质分裂沟的位置由有丝分裂纺锤体的位置决定。胞质分裂沟在微管星体之间的纺锤体中部、基于微管的中间区位置将纺锤体一分为二，从而产生两个子细胞。在某些细胞类型中的实验表明中间区决定沟的位置，但在其他细胞中的实验则表明星体决定沟的位置。一种可能性是不同的生物体和细胞类型使用不同的机制来定位胞质分裂沟。另一种可能性是星体和中间区都对沟的定位有贡献。秀丽隐杆线虫最近的研究表明中心体分离和中间区与胞质分裂有关。在这里，我们研究了有丝分裂纺锤体不同部分对秀丽隐杆线虫受精卵中胞质分裂沟定位的相对贡献。通过使用紫外激光将纺锤体中间区与其中一个星体在空间上分离，我们表明胞质分裂沟首先由微管星体决定的信号定位，然后由来自纺锤体中间区的第二个信号定位。因此，胞质分裂沟的位置由两个连续的沟形成活动决定。
