Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, MO 63110, USA.
Curr Biol. 2009 Dec 15;19(23):2026-30. doi: 10.1016/j.cub.2009.10.020. Epub 2009 Nov 12.
The objective of mitosis is to provide a copy of the genome to each progeny of a cell division. This requires the separation of duplicate chromatids by the spindle apparatus and the delivery of one set of chromosomes to each of the daughter cells. In budding yeast, the fidelity of chromosome delivery depends on the spindle position checkpoint, which prolongs mitosis until one end of the anaphase spindle arrives in the bud. Here we tested the hypothesis that the activity of the spindle position checkpoint depends on persistent interactions between cytoplasmic microtubules and the mother-bud neck, the future site of cytokinesis. We used laser ablation to disrupt microtubule interactions with the bud neck, and we found that loss of microtubules from the neck leads to mitotic exit in a majority of checkpoint-activated cells. Our findings suggest that cytoplasmic microtubules are used to monitor the location of the spindle in the dividing cell and, in the event of positioning errors, relay a signal to inhibit mitotic exit until the spindle is appropriately positioned.
有丝分裂的目的是为细胞分裂的每个后代提供一份基因组副本。这需要纺锤体装置将重复的染色单体分开，并将一组染色体分配到每个子细胞中。在芽殖酵母中，染色体传递的保真度取决于纺锤体位置检查点，该检查点会延长有丝分裂，直到后期纺锤体的一端到达芽中。在这里，我们测试了这样一个假设，即纺锤体位置检查点的活性取决于细胞质微管与母-芽颈之间的持续相互作用，芽颈是细胞分裂的未来位点。我们使用激光消融破坏微管与芽颈的相互作用，我们发现芽颈处的微管消失会导致大多数检查点激活的细胞退出有丝分裂。我们的发现表明，细胞质微管用于监测分裂细胞中纺锤体的位置，如果出现定位错误，就会传递信号抑制有丝分裂退出，直到纺锤体被适当地定位。
