Center for Cell Dynamics, Friday Harbor Laboratories, University of Washington, Seattle, WA 98250, USA.
J Cell Biol. 2009 Dec 14;187(6):831-45. doi: 10.1083/jcb.200907090.
Animal cells decide where to build the cytokinetic apparatus by sensing the position of the mitotic spindle. Reflecting a long-standing presumption that a furrow-inducing stimulus travels from spindle to cortex via microtubules, debate continues about which microtubules, and in what geometry, are essential for accurate cytokinesis. We used live imaging in urchin and frog embryos to evaluate the relationship between microtubule organization and cytokinetic furrow position. In normal cells, the cytokinetic apparatus forms in a region of lower cortical microtubule density. Remarkably, cells depleted of astral microtubules conduct accurate, complete cytokinesis. Conversely, in anucleate cells, asters alone can support furrow induction without a spindle, but only when sufficiently separated. Ablation of a single centrosome displaces furrows away from the remaining centrosome; ablation of both centrosomes causes broad, inefficient furrowing. We conclude that the asters confer accuracy and precision to a primary furrow-inducing signal that can reach the cell surface from the spindle without transport on microtubules.
动物细胞通过感知有丝分裂纺锤体的位置来决定在哪里构建细胞分裂装置。这反映了一个长期以来的假设，即沟诱导刺激物通过微管从纺锤体传递到皮质，关于哪些微管以及以何种几何形状对于准确的胞质分裂是必不可少的，这一争论仍在继续。我们使用海胆和青蛙胚胎的实时成像来评估微管组织与胞质分裂沟位置之间的关系。在正常细胞中，细胞分裂装置形成于皮质微管密度较低的区域。值得注意的是，耗尽星体微管的细胞能够进行准确、完整的胞质分裂。相反，在去核细胞中，星状体本身可以在没有纺锤体的情况下支持沟的诱导，但前提是它们之间有足够的距离。切除一个中心体将沟从剩余的中心体移开；切除两个中心体导致广泛而低效的沟形成。我们得出结论，星状体赋予了一个主要的沟诱导信号以准确性和精密度，该信号可以从纺锤体直接到达细胞表面，而不需要微管运输。
