Yang Ching-Po, Fan Seng-Sheen
Department of Life Science, Tunghai University, Taichung, Taiwan, ROC.
Exp Cell Res. 2008 Oct 15;314(17):3209-20. doi: 10.1016/j.yexcr.2008.08.004. Epub 2008 Aug 19.
Spindle assembly is essential for the equal distribution of genetic material to the daughter cells during mitosis. The process of spindle assembly is complicated and involves multiple levels of molecular regulation. It is generally accepted that mitotic spindles are emanated from the centrosomes and are assembled in the vicinity of chromosomes. However, the molecular mechanism involved in the spindle assembly during mitosis remains unclear. In this study, we have provided several lines of evidence to show that Drosophila Mars is required for the assembly and stabilization of kinetochore microtubules. In an immunocytochemical study, we show that Mars is mainly localized on the kinetochore microtubules during mitosis. Using RNA interference to deplete the Mars expression in Drosophila S2 cells resulted in the malformation of mitotic spindle that mainly lacked the kinetochore microtubules. The spindle defect resulted in mitotic delays by increasing the percentage of uncongressed chromosomes both in vitro and in vivo. In summary, this study has extended our previous study of Mars in cell cycle regulation and provided further evidence showing that Mars is required for the assembly of kinetochore microtubules.
纺锤体组装对于有丝分裂期间遗传物质向子细胞的均等分配至关重要。纺锤体组装过程复杂，涉及多个层面的分子调控。人们普遍认为有丝分裂纺锤体源自中心体，并在染色体附近组装。然而，有丝分裂期间纺锤体组装所涉及的分子机制仍不清楚。在本研究中，我们提供了多条证据表明果蝇Mars蛋白是动粒微管组装和稳定所必需的。在一项免疫细胞化学研究中，我们表明Mars蛋白在有丝分裂期间主要定位于动粒微管上。利用RNA干扰降低果蝇S2细胞中Mars蛋白的表达，导致有丝分裂纺锤体畸形，主要表现为缺乏动粒微管。纺锤体缺陷通过增加体外和体内未排列的染色体百分比导致有丝分裂延迟。总之，本研究扩展了我们之前对Mars蛋白在细胞周期调控方面的研究，并提供了进一步的证据表明Mars蛋白是动粒微管组装所必需的。
