Dorer Russell K, Zhong Sheng, Tallarico John A, Wong Wing Hung, Mitchison Timothy J, Murray Andrew W
Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Curr Biol. 2005 Jun 7;15(11):1070-6. doi: 10.1016/j.cub.2005.05.020.
The spindle checkpoint prevents chromosome loss by preventing chromosome segregation in cells with improperly attached chromosomes [1, 2 and 3]. The checkpoint senses defects in the attachment of chromosomes to the mitotic spindle [4] and the tension exerted on chromosomes by spindle forces in mitosis [5, 6 and 7]. Because many cancers have defects in chromosome segregation, this checkpoint may be required for survival of tumor cells and may be a target for chemotherapy. We performed a phenotype-based chemical-genetic screen in budding yeast and identified an inhibitor of the spindle checkpoint, called cincreasin. We used a genome-wide collection of yeast gene-deletion strains and traditional genetic and biochemical analysis to show that the target of cincreasin is Mps1, a protein kinase required for checkpoint function [8]. Despite the requirement for Mps1 for sensing both the lack of microtubule attachment and tension at kinetochores, we find concentrations of cincreasin that selectively inhibit the tension-sensitive branch of the spindle checkpoint. At these concentrations, cincreasin causes lethal chromosome missegregation in mutants that display chromosomal instability. Our results demonstrate that Mps1 can be exploited as a target and that inhibiting the tension-sensitive branch of the spindle checkpoint may be a way of selectively killing cancer cells that display chromosomal instability.
纺锤体检查点通过阻止染色体未正确附着的细胞中的染色体分离来防止染色体丢失[1,2和3]。该检查点可感知染色体与有丝分裂纺锤体附着的缺陷[4]以及有丝分裂中纺锤体力量对染色体施加的张力[5,6和7]。由于许多癌症在染色体分离方面存在缺陷，该检查点可能是肿瘤细胞存活所必需的，并且可能是化疗的靶点。我们在芽殖酵母中进行了基于表型的化学遗传学筛选，并鉴定出一种纺锤体检查点抑制剂，称为cincreasin。我们使用全基因组酵母基因缺失菌株集合以及传统的遗传和生化分析表明，cincreasin的靶点是Mps1，这是一种检查点功能所需的蛋白激酶[8]。尽管Mps1对于感知动粒处微管附着的缺乏和张力都很必要，但我们发现cincreasin的浓度可选择性地抑制纺锤体检查点的张力敏感分支。在这些浓度下，cincreasin会在显示染色体不稳定的突变体中导致致命的染色体错分离。我们的结果表明，Mps1可被用作靶点，并且抑制纺锤体检查点的张力敏感分支可能是选择性杀死显示染色体不稳定的癌细胞的一种方法。
