Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
Curr Biol. 2010 Feb 23;20(4):353-8. doi: 10.1016/j.cub.2009.12.050. Epub 2010 Feb 4.
Just as the size of an organism is carefully controlled, the size of intracellular structures must also be regulated. The mitotic spindle is a supramolecular machine that generates the forces which separate sister chromatids during mitosis. Although spindles show little size variation between cells of the same type, spindle length can vary at least 10-fold between different species. Recent experiments on spindle length showed that in embryonic systems spindle length varied with blastomere size. Furthermore, a comparison between two Xenopus species showed that spindle length was dependent on some cytoplasmic factor. These data point toward mechanisms to scale spindle length with cell size. Centrosomes play an important role in organizing microtubules during spindle assembly. Here we use Caenorhabditis elegans to study the role of centrosomes in setting spindle length. We show that spindle length correlates with centrosome size through development and that a reduction of centrosome size by molecular perturbation reduces spindle length. By systematically analyzing centrosome proteins, we show that spindle length does not depend on microtubule density at centrosomes. Rather, our data suggest that centrosome size sets mitotic spindle length by controlling the length scale of a TPXL-1 gradient along spindle microtubules.
正如生物体的大小受到精细调控一样，细胞内结构的大小也必须受到调控。有丝分裂纺锤体是一种超分子机器，它产生在有丝分裂过程中分离姐妹染色单体的力。尽管纺锤体在同一类型的细胞之间显示出很小的大小变化，但纺锤体的长度在不同物种之间至少可以变化 10 倍。最近关于纺锤体长度的实验表明，在胚胎系统中，纺锤体的长度随卵裂球的大小而变化。此外，对两种非洲爪蟾物种的比较表明，纺锤体的长度取决于一些细胞质因子。这些数据表明存在一些机制可以根据细胞大小来调节纺锤体的长度。中心体在纺锤体组装过程中对微管的组织起着重要作用。在这里，我们使用秀丽隐杆线虫来研究中心体在设定纺锤体长度方面的作用。我们表明，通过发育，纺锤体的长度与中心体的大小相关，并且通过分子干扰减少中心体的大小会降低纺锤体的长度。通过系统地分析中心体蛋白，我们表明纺锤体的长度不依赖于中心体处的微管密度。相反，我们的数据表明，中心体的大小通过控制纺锤体微管上 TPXL-1 梯度的长度尺度来设定有丝分裂纺锤体的长度。
