How does Condensin mediate topological change during mitosis?

Condensin 如何介导有丝分裂过程中的拓扑变化？

• 批准号: BB/J018554/1
• 负责人: Jonathan Baxter
• 金额: $ 56.64万
• 依托单位: University of Sussex
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FJ018554%2F1
• 关键词: How; does; Condensin; mediate; topological

Maintaining genome stability is essential for normal cellular function. Cellular defects that lead to loss or duplication of genetic information can lead to cell death, cancer or premature aging. Maintenance of genome stability is a particularly acute problem in dividing cells. Every time a cell divides, every one of the chromosomes that makes up the genome must be perfectly copied. The two copies must then fully resolved from one other and finally one copy of every chromosome transported into each daughter cell. Failure to faithfully complete any or these steps could have disastrous effects on genome stability.Understanding how cellular proteins work together to maintain genome instability is therefore crucial to understanding why cells become cancerous or defective with age. The SMC family of proteins appear crucial to genome stability in all organisms from bacteria to humans. The SMC proteins form several different complexes in the cell but in all cases they appear to function by influencing chromosome structure.One of the SMC complexes called condensin appears to be important for chromosomal compaction in mitosis. How condensin compacts chromosomes remains enigmatic although it has been shown in the test tube to generate supercoiled "spring like" structures in DNA. Recently I have shown that similar structures are formed in cells just before the chromosomes are segregated. This change in chromosome structure promotes the resolution of the chromosomes and so appears crucial for chromosome stability.The work in this proposal aims to demonstrate how the condensin complex changes chromosome structure in order to promote genome stability. It will first use molecular biology techniques to modify distinct regions of the condensin factors SMC2 and SMC4. We will then use these modified proteins to assess how specific aspects of SMC2 and SMC4 function are required to generate supercoiled structures in the cells. The ability of the altered proteins to generate supercoiled structures will then be related to how condensin alters chromosome organisation and the cells ability to ensure that one whole copy of each chromosome is segregated to each daughter cell. These experiments aim to provide a detailed description of what aspects of SMC/condensin function are required to change chromosome structure inside cells. We will then use this information to recreate the situation in a test tube and so generate a system where we will be able to fully describe how condensin achieves its function.Using this combination of approaches this work aims to provide unique insights into how SMC/condensin proteins, and potentially all other SMC proteins help maintain genome stability. The information generated by this project will be of general interest not only to researchers studying genome stability but also for research into ageing and cancer evolution.

维持基因组稳定性对正常细胞功能至关重要。导致遗传信息丢失或复制的细胞缺陷可导致细胞死亡、癌症或过早衰老。维持基因组稳定性是分裂细胞中特别严重的问题。每次细胞分裂时，组成基因组的每一条染色体都必须被完美地复制。这两个拷贝必须完全分离，最后每个染色体的一个拷贝被运送到每个子细胞中。如果不能忠实地完成任何一个步骤，都可能对基因组的稳定性产生灾难性的影响。因此，了解细胞蛋白质如何协同工作以维持基因组的不稳定性，对于了解细胞为什么会随着年龄的增长而癌变或有缺陷至关重要。SMC家族的蛋白质似乎对从细菌到人类的所有生物体的基因组稳定性至关重要。SMC蛋白质在细胞中形成几种不同的复合物，但在所有情况下，它们似乎都是通过影响染色体结构来发挥作用的，其中一种称为凝聚素的SMC复合物似乎对有丝分裂中的染色体压实很重要。凝聚素如何压缩染色体仍然是一个谜，尽管它已经在试管中显示出在DNA中产生超螺旋的“弹簧状”结构。最近，我证明了在染色体分离之前，细胞中也会形成类似的结构。染色体结构的这种变化促进了染色体的分辨率，因此对染色体稳定性至关重要。本提案中的工作旨在证明凝聚素复合物如何改变染色体结构以促进基因组稳定性。它将首先使用分子生物学技术来修饰凝聚素因子SMC 2和SMC 4的不同区域。然后，我们将使用这些修饰的蛋白质来评估SMC 2和SMC 4功能的特定方面如何在细胞中产生超螺旋结构。然后，改变的蛋白质产生超螺旋结构的能力将与凝聚素如何改变染色体组织以及细胞确保每个染色体的一个完整拷贝被分离到每个子细胞的能力有关。这些实验旨在提供SMC/凝聚素功能的哪些方面需要改变细胞内的染色体结构的详细描述。然后我们将使用这些信息在试管中重现这种情况，从而生成一个系统，在该系统中我们将能够充分描述凝聚素如何实现其功能。使用这种方法的组合，这项工作的目的是提供独特的见解SMC/凝聚素蛋白，以及潜在的所有其他SMC蛋白如何帮助维持基因组稳定性。该项目产生的信息不仅对研究基因组稳定性的研究人员，而且对衰老和癌症演变的研究都具有普遍意义。

项目成果

Cohesin dependent compaction of mitotic chromosomes

有丝分裂染色体的粘连蛋白依赖性压缩

• DOI: 10.1101/094946
• 发表时间: 2016
• 作者: Schalbetter S

SMC complexes differentially compact mitotic chromosomes according to genomic context.

• DOI: 10.1038/ncb3594
• 发表时间: 2017-09
• 期刊: Nature cell biology
• 影响因子: 21.3
• 作者: Schalbetter SA;Goloborodko A;Fudenberg G;Belton JM;Miles C;Yu M;Dekker J;Mirny L;Baxter J
• 通讯作者: Baxter J

Principles of meiotic chromosome assembly revealed in S. cerevisiae

• DOI: 10.1038/s41467-019-12629-0
• 发表时间: 2019-10
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: S. Schalbetter;G. Fudenberg;J. Baxter;K. Pollard;Matthew J. Neale

Separable functions of Tof1/Timeless in intra-S-checkpoint signalling, replisome stability and DNA topological stress

Tof1/Timeless 在 S-检查点内信号传导、复制体稳定性和 DNA 拓扑应激中的可分离功能

• DOI: 10.1101/2019.12.17.877811
• 发表时间: 2019
• 作者: Westhorpe R

Separable functions of Tof1/Timeless in intra-S-checkpoint signalling, replisome stability and DNA topological stress.

• DOI: 10.1093/nar/gkaa963
• 发表时间: 2020-12-02
• 期刊: Nucleic acids research
• 影响因子: 14.9
• 作者: Westhorpe R;Keszthelyi A;Minchell NE;Jones D;Baxter J
• 通讯作者: Baxter J