Ho Chin-Yee, Wong Chi-Hang, Li Hoi-Yeung
Division of Molecular and Cell Biology, School of Biological Sciences, College of Science, Nanyang Technological University, Singapore 637551, Singapore.
J Cell Biochem. 2008 Oct 15;105(3):835-46. doi: 10.1002/jcb.21879.
Mitotic catastrophe is a form of cell death that results from aberrant mitosis. Currently, the mechanisms involved in this form of cell death remain poorly understood. We found that actinomycin D induces mitotic catastrophe with severe spindle assembly defects. We have studied the nature of three groups of chromosome binding proteins in mitotic cells treated with actinomycin D. We found that actinomycin D reduced the binding affinity of RCC1 to the mitotic chromosome, which led to a reduction of RanGTP level. In addition, Mad2 was not concentrated at the kinetochores, indicating that the mitotic spindle checkpoint was affected. Furthermore, the localization of survivin was altered in cells. These data suggested that chromosomal binding of the mitotic regulators such as RCC1, Mad2 and survivin is essential for mitotic progression. Mitotic chromosomes not only carry the genetic material needed for the newly synthesized daughter cells, but also serve as docking sites for some of the mitotic regulators. Perturbation of their binding to the mitotic chromosome by actinomycin D could affect their functions in regulating mitotic progression thus leading to severe spindle defects and mitotic catastrophe.
有丝分裂灾难是一种由异常有丝分裂导致的细胞死亡形式。目前,这种细胞死亡形式所涉及的机制仍知之甚少。我们发现放线菌素D会诱导有丝分裂灾难,并伴有严重的纺锤体组装缺陷。我们研究了用放线菌素D处理的有丝分裂细胞中三组染色体结合蛋白的性质。我们发现放线菌素D降低了RCC1与有丝分裂染色体的结合亲和力,这导致RanGTP水平降低。此外,Mad2没有集中在动粒上,这表明有丝分裂纺锤体检查点受到了影响。此外,细胞中生存素的定位发生了改变。这些数据表明,有丝分裂调节因子如RCC1、Mad2和生存素的染色体结合对于有丝分裂进程至关重要。有丝分裂染色体不仅携带新合成的子细胞所需的遗传物质,还作为一些有丝分裂调节因子的停靠位点。放线菌素D对它们与有丝分裂染色体结合的干扰可能会影响它们在调节有丝分裂进程中的功能,从而导致严重的纺锤体缺陷和有丝分裂灾难。