Genomic Health & Safety: Does Elg1 maintain genome stability by resetting chromatin factors used in DNA replication and repair?

基因组健康

• 批准号: MR/L019698/1
• 负责人: Takashi Kubota
• 金额: $ 123.21万
• 依托单位: University of Aberdeen
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FL019698%2F1
• 关键词: Genomic; Health; Safety; Does; Elg1

The preservation of correct and accurate information is critical in almost all aspects of life. The information that enables life is encoded in DNA, which is folded up with proteins inside cells to form chromosomes. The failure to maintain chromosomes leads to the loss of or rewriting of important information, which can cause cancer and other diseases. The protein called Elg1 is a cellular factor that is very important in maintaining chromosomes. Defects in this one protein cause tumors in humans and mice, but we do not know why. The aim of this work is to understand how the Elg1 protein maintains chromosome stability so that we may exploit these findings to develop new cancer therapies.Whenever a cell divides to produce two new cells, the genetic information in the chromosomes must be duplicated precisely. This duplication process is called DNA replication. In most cases, cells achieve precise DNA replication without any mistakes. Hundreds of proteins in cells contribute to such precise DNA replication. If such 'chromosome stability' proteins cannot carry out their proper functions, cell cannot duplicate genetic information precisely, resulting in loss of or rewriting of important information, and leading eventually to cancer, genetic disorders, and ageing. A protein called Elg1 is one of these chromosome stability proteins. Recently I discovered that the molecular function of Elg1 is removal of a sliding clamp called PCNA from DNA during DNA replication. PCNA is ring-shaped and encircles DNA. PCNA stabilises the machinery that copies DNA, and additionally the PCNA ring acts like a tool-belt, recruiting many other collaborating proteins that are important for chromosome maintenance and precise DNA replication. During DNA replication, the PCNA tool-belt is repeatedly loaded on DNA, and repeatedly removed from DNA by Elg1 after each section of the DNA replication task is complete. In cells lacking Elg1, the PCNA tool-belt and its tools (i.e. its collaborating proteins) accumulate on chromosomes since the PCNA tool-belt is not removed even after completion of each new DNA section. This abnormal accumulation of the PCNA tool-belt resembles a construction worker with ten tool-belts around his body, each containing several unnecessary tools. Workers carrying ten tool-belts and lots of unnecessary tools may be not able to move their bodies flexibly, respond effectively to unexpected events, or use tools efficiently-and so will be more liable to make mistakes. In chromosome stablity, even occasional mistakes may cause catastrophe. My hypothesis is that the aberrant accumulation on DNA of the PCNA tool-belt and its associated tools causes loss of or rewriting of genetic information during chromosome duplication, ultimately resulting in cancer. I aim to understand why PCNA removal by Elg1 is important for chromosome maintenance, and whether its collaborating proteins are involved. First, by manipulating the PCNA tool-belt, I will test whether unwanted accumulation of the PCNA tool-belt interferes directly with chromosome maintenance. Next I will test whether the accumulation of particular unnecessary tools (i.e. unwanted retention of the collaborating proteins) contributes to chromosome instability. These experiments will be carried out using the baker's yeast system, which allows sophisticated molecular genetic approaches to be used for careful dissection of the chromosome stability machinery. In the third part, I am keen to extend this investigation to test the role of Elg1 in human cells, since loss of Elg1 is directly implicated in mammalian tumors. Since this project studies the mechanism of action of gene that is associated with cancer, this work holds long-term potential for cancer therapy.

保存正确和准确的信息几乎在生活的各个方面都是至关重要的。使生命得以存在的信息被编码在DNA中，DNA与细胞内的蛋白质折叠形成染色体。染色体维护的失败会导致重要信息的丢失或重写，从而导致癌症和其他疾病。这种名为Elg1的蛋白质是一种细胞因子，对维持染色体非常重要。这种蛋白质的缺陷会导致人类和老鼠的肿瘤，但我们不知道原因。这项工作的目的是了解Elg1蛋白如何维持染色体稳定性，以便我们可以利用这些发现开发新的癌症治疗方法。每当一个细胞分裂产生两个新细胞时，染色体中的遗传信息必须精确地复制。这种复制过程被称为DNA复制。在大多数情况下，细胞实现精确的DNA复制，没有任何错误。细胞中的数百种蛋白质有助于这种精确的DNA复制。如果这种“染色体稳定”蛋白不能发挥其应有的功能，细胞就不能精确地复制遗传信息，导致重要信息的丢失或重写，最终导致癌症、遗传疾病和衰老。一种叫做Elg1的蛋白质是这些染色体稳定蛋白之一。最近我发现Elg1的分子功能是在DNA复制过程中从DNA中移除一个叫做PCNA的滑动夹。PCNA呈环状，环绕着DNA。PCNA稳定了复制DNA的机制，此外，PCNA环就像一个工具带，招募许多其他合作蛋白质，这些蛋白质对染色体的维持和精确的DNA复制很重要。在DNA复制过程中，PCNA工具带被反复加载到DNA上，并在每段DNA复制任务完成后被Elg1反复从DNA上移除。在缺乏Elg1的细胞中，PCNA工具带及其工具（即其协作蛋白）在染色体上积累，因为PCNA工具带即使在每个新的DNA片段完成后也不会被移除。PCNA工具带的这种异常积累就像一个建筑工人身上有十个工具带，每一个都有几个不必要的工具。工人们携带10条工具带和许多不必要的工具，可能无法灵活地移动他们的身体，对意外事件做出有效的反应，或者有效地使用工具，因此更容易出错。在染色体稳定性方面，即使偶然的错误也可能导致灾难。我的假设是，PCNA工具带及其相关工具在DNA上的异常积累导致染色体复制过程中遗传信息的丢失或重写，最终导致癌症。我的目的是了解为什么Elg1去除PCNA对染色体维持很重要，以及它的合作蛋白是否参与其中。首先，通过操纵PCNA工具带，我将测试PCNA工具带的不必要积累是否直接干扰染色体维持。接下来，我将测试特定的不必要工具的积累（即不需要的合作蛋白的保留）是否会导致染色体不稳定。这些实验将使用面包师酵母系统进行，该系统允许使用复杂的分子遗传学方法来仔细解剖染色体稳定机制。在第三部分中，我希望将这项研究扩展到测试Elg1在人类细胞中的作用，因为Elg1的缺失与哺乳动物肿瘤有直接关系。由于本项目研究的是与癌症相关的基因的作用机制，因此具有长期的癌症治疗潜力。

项目成果

Ligation of newly replicated DNA controls the timing of DNA mismatch repair.

• DOI: 10.1016/j.cub.2020.12.018
• 发表时间: 2021-03-22
• 期刊: Current biology : CB
• 作者: Reyes GX;Kolodziejczak A;Devakumar LJPS;Kubota T;Kolodner RD;Putnam CD;Hombauer H
• 通讯作者: Hombauer H

SWI/SNF and the histone chaperone Rtt106 drive expression of the Pleiotropic Drug Resistance network genes.

• DOI: 10.1038/s41467-022-29591-z
• 发表时间: 2022-04-12
• 期刊: Nature communications
• 影响因子: 16.6

Replication-Coupled PCNA Unloading by the Elg1 Complex Occurs Genome-wide and Requires Okazaki Fragment Ligation.

• DOI: 10.1016/j.celrep.2015.06.066
• 发表时间: 2015-08-04
• 期刊: Cell reports
• 影响因子: 8.8
• 作者: Kubota T;Katou Y;Nakato R;Shirahige K;Donaldson AD
• 通讯作者: Donaldson AD

PCNA Retention on DNA into G2/M Phase Causes Genome Instability in Cells Lacking Elg1.

• DOI: 10.1016/j.celrep.2016.06.030
• 发表时间: 2016-07-19
• 期刊: Cell reports
• 影响因子: 8.8
• 作者: Johnson C;Gali VK;Takahashi TS;Kubota T
• 通讯作者: Kubota T