Regulation of cell cycle transitions by cyclin-dependent kinase in trypanosomes

项目概要 细胞周期调控研究的一个中心问题是如何控制细胞周期转变 允许在适当的时间过渡到下一个细胞周期阶段？这种控制机制对于 保持基因组完整性，因为从细胞周期的一个阶段到下一阶段的过早转变 可导致非整倍体，从而导致细胞死亡。四个主要的细胞周期转变点：G1/S 转变、 G2/M 转变、中期/后期转变和有丝分裂/细胞分裂转变受到严格限制 控制，但它们如何在T. brucei（一种原生动物寄生虫及其致病原因）的分子水平上受到调节 人类昏睡病的病原体，目前仍知之甚少。细胞周期蛋白依赖性激酶 (CDK) 是关键 T. brucei 是真核生物细胞周期转变的调节因子，T. brucei 利用 CDK 相关激酶 CRK1 CRK2 控制 G1/S 转变，CRK2 促进 S 期进展，CRK3 控制 G2/M 转变。 CRK1在控制核事件促进G1/S转变中的作用以及CRK2在促进G1/S转变中的作用 我们最近揭示了调节 S 期进展的方法。然而，分子机制 G2/M 转变和中期/后期转变的基础仍然难以捉摸。此外，一般来说 承认布氏锥虫缺乏几个细胞周期检查点，包括纺锤体组装检查点，并且它 目前还不清楚布氏锥虫如何识别细胞周期中发生的基因组错误并防止错误发生 基因组复制和过早的基因组分离。我们最近发现了一种新的 DNA 损伤—— 诱导的中期检查点表明 T. brucei 中存在基于动粒的检查点机制，但 根本机制仍然很大程度上未知。当前的提案旨在了解对 G2/M 转变通过 CRK3 介导的染色体过客复合体调控， CRK3介导的着丝粒蛋白调节的中期/后期转变及其机制 由 KKIP5 及其相关蛋白介导的中期检查点。这些结果 研究不仅具有重要的生物学意义，而且可以为抗肿瘤药物提供新的靶点。 锥虫病化疗。

Project Summary A central question in the study of cell cycle regulation is, how the cell cycle transitions are controlled to allow the transition to the next cell cycle stage at a right time? Such control mechanisms are critical for maintaining genome integrity because premature transition from one stage to the next stage of the cell cycle can lead to aneuploidy and, hence, cell death. Four major cell cycle transition points, the G1/S transition, the G2/M transition, the metaphase/anaphase transition, and the mitosis/cytokinesis transition, are under stringent control, but how they are regulated at the molecular level in T. brucei, a protozoan parasite and the causative agent of human sleeping sickness, remains poorly understood. Cyclin-dependent kinases (CDKs) are key regulators of the cell cycle transitions in eukaryotes, and T. brucei employs the CDK-related kinase CRK1 to control the G1/S transition, CRK2 to promote S-phase progression, and CRK3 to govern the G2/M transition. The roles of CRK1 in controlling the nuclear events in promoting the G1/S transition and the role of CRK2 in regulating S-phase progression have been recently revealed by us. However, the molecular mechanisms underlying the G2/M transition and the metaphase/anaphase transition are still elusive. Further, it is generally accepted that T. brucei lacks several cell cycle checkpoints, including the spindle assembly checkpoint, and it is unclear how T. brucei recognizes the genomic errors occurred during the cell cycle and prevents erroneous genome duplication and premature genome segregation. Our recent discovery of a novel DNA damage- induced metaphase checkpoint suggests a kinetochore-based checkpoint machinery in T. brucei, but the underlying mechanism remains largely unknown. The current proposal aims to understand the control of the G2/M transition by CRK3-mediated regulation of the chromosomal passenger complex, the control of metaphase/anaphase transition by CRK3-mediated regulation of kinetochore proteins, and the mechanism of the metaphase checkpoint mediated by KKIP5 and its associated proteins. The outcomes from these investigations not only will have important biological significance, but also could provide novel targets for anti- trypanosomiasis chemotherapy.