Mechanisms of spindle checkpoint silencing

纺锤体检查点沉默机制

• 批准号: MR/K001000/1
• 负责人: Jonathan Millar
• 金额: $ 234.86万
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FK001000%2F1
• 关键词: Mechanisms; spindle; checkpoint; silencing

This project is about understanding how cells ensure chromosomes are segregated equally to daughter cells. Human beings are built from around 100 trillion individual cells. Each cell contains 46 chromosomes into which is packaged our genetic material (DNA, deoxyribonucleic acid), which provides the instructions for how a cell should work and how a whole organism should be built. This huge number of cells originates from a single cell that is the result of fertilization of an egg with a sperm. This single cell needs to be able to divide itself to generate two new daughter cells, which then also divide to produce further cells; this process repeats until the correct number of cells are generated. Moreover, cells do not live forever and are constantly being replaced by new ones. Thus, cell division is fundamental to the existence of life. A key part of cell division involves the accurate separation of the chromosomes into the two daughter cells - a process called mitosis. It is crucial that each daughter cell receives a complete set of chromosomes. We know that having the wrong number of chromosomes is a cause of multiple human diseases, most notably cancer where greater than 80% of human tumors have the wrong number of chromosomes. Indeed, altering chromosome number experimentally in mice has been shown to cause cancer. Secondly, many developmental disorders are the result of mistakes in chromosome separation such as Downs Syndrome, in which cells have an extra copy of chromosome 21. A large proportion of miscarriages are also caused by problems in chromosome separation. It is clearly vital that we work out how the process of chromosome segregation is controlled and why these controls are defective or over-ridden in these diseases. Each chromosome is made up of two sister chromatids that are stuck together after the cell replicates its DNA. To separate these two sister chromatids (one to each of the two daughter cells), the cell makes use of molecular cables called microtubules. Each sister chromatid has a "hook" called the kinetochore, which can attach to the end of a microtubule cable. As the cables attached to the two sister chromatids grow and shrink the chromosomes are moved around inside the cell. This jostling motion allows the chromosomes to line up in the middle of the cell. When everything is ready, the glue joining the two sister chromatids is removed and the sister chromatids are pulled to opposite daughter cells.But how is this process controlled? It turns out that the kinetochore also operates as the control centre for a monitoring system, called the spindle assembly checkpoint, which ensures that sister chromatids do not separate until the alignment process is complete. We have recently discovered the central players in this process but we do not yet understand how they are controlled nor how this system operates.The experiments that we will do will help answer these exciting and intriguing questions and therefore advance our understanding of how chromosomes are separated equally into daughter cells during cell division. To do this we will use state-of-the-art imaging technology (powerful microscopes) and modern techniques in molecular genetics and biochemistry to observe how chromosomes move in living cells and how the factors involved operate. The answers to these questions will help the identification of new targets and therapies to combat disease.

该项目旨在了解细胞如何确保染色体与子细胞平等分离。人类是由大约 100 万亿个单个细胞构成的。每个细胞包含 46 条染色体，其中包装着我们的遗传物质（DNA、脱氧核糖核酸），它为细胞如何工作以及整个有机体如何构建提供了指导。如此大量的细胞源自单个细胞，该细胞是卵子与精子受精的结果。这个单细胞需要能够自我分裂以产生两个新的子细胞，然后子细胞也分裂产生更多的细胞；重复此过程直到生成正确数量的细胞。此外，细胞不会永远存活，并且会不断被新细胞取代。因此，细胞分裂是生命存在的基础。细胞分裂的一个关键部分涉及将染色体准确分离到两个子细胞中，这一过程称为有丝分裂。每个子细胞接收一套完整的染色体至关重要。我们知道，染色体数量错误是多种人类疾病的原因之一，其中最著名的是癌症，其中超过 80% 的人类肿瘤的染色体数量错误。事实上，通过实验改变小鼠染色体数量已被证明会导致癌症。其次，许多发育障碍是染色体分离错误的结果，例如唐氏综合症，其中细胞有一个额外的21号染色体副本。很大一部分流产也是由染色体分离问题引起的。显然，我们必须弄清楚染色体分离过程是如何被控制的，以及为什么这些控制在这些疾病中存在缺陷或被过度利用。每条染色体均由两条姐妹染色单体组成，在细胞复制其 DNA 后，这两条姐妹染色单体粘在一起。为了分离这两个姐妹染色单体（两个子细胞各一个），细胞利用称为微管的分子电缆。每个姐妹染色单体都有一个称为动粒的“钩子”，它可以附着在微管电缆的末端。随着连接到两个姐妹染色单体的电缆生长和收缩，染色体在细胞内移动。这种推挤运动使染色体能够在细胞中间排列。当一切准备就绪后，连接两个姐妹染色单体的胶水被去除，姐妹染色单体被拉向相对的子细胞。但是这个过程是如何控制的呢？事实证明，着丝粒还充当监控系统的控制中心，称为纺锤体装配检查点，它确保姐妹染色单体在对齐过程完成之前不会分离。我们最近发现了这个过程中的核心参与者，但我们还不知道它们是如何被控制的，也不知道这个系统是如何运作的。我们将要做的实验将有助于回答这些令人兴奋和有趣的问题，从而增进我们对细胞分裂过程中染色体如何平均分离到子细胞中的理解。为此，我们将使用最先进的成像技术（功能强大的显微镜）以及分子遗传学和生物化学领域的现代技术来观察染色体如何在活细胞中移动以及所涉及的因素如何运作。这些问题的答案将有助于确定对抗疾病的新靶点和疗法。

项目成果

Checkpoint proteins come under scrutiny.

• DOI: 10.7554/elife.01494
• 发表时间: 2013-10-08
• 期刊: eLife
• 影响因子: 7.7
• 作者: Mora-Santos M;Millar JB
• 通讯作者: Millar JB

Some assembly required: Redefining the mitotic checkpoint.

• DOI: 10.1080/23723556.2017.1314238
• 发表时间: 2017
• 期刊: Molecular & cellular oncology
• 影响因子: 2.1
• 作者: Meadows JC;Millar JBA
• 通讯作者: Millar JBA

Role and regulation of kinesin-8 motors through the cell cycle.

• DOI: 10.1007/s11693-014-9140-z
• 发表时间: 2014-09-01
• 期刊: Systems and synthetic biology
• 作者: Messin, Liam J;Millar, Jonathan B A
• 通讯作者: Millar, Jonathan B A

Opposing kinesin complexes queue at plus tips to ensure microtubule catastrophe at cell ends.

• DOI: 10.15252/embr.201846196
• 发表时间: 2018-11
• 期刊: EMBO reports
• 影响因子: 7.7
• 作者: Meadows JC;Messin LJ;Kamnev A;Lancaster TC;Balasubramanian MK;Cross RA;Millar JB
• 通讯作者: Millar JB

Cell biology: polar expeditions for PP1.

细胞生物学：PP1 的极地探险。

• DOI: 10.1016/j.cub.2012.12.020
• 发表时间: 2013
• 期刊: CB
• 作者: Meadows JC