Termination of DNA replication - a novel threat to genomic stability and cell cycle control

DNA 复制的终止——对基因组稳定性和细胞周期控制的新威胁

• 批准号: BB/K015729/1
• 负责人: Christian Rudolph
• 金额: $ 51.46万
• 依托单位: Brunel University London
• 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=BB%2FK015729%2F1
• 关键词: Termination; DNA; replication; novel; threat

Cancer is rapidly becoming one of the most common causes of death in human populations, and more than one in three individuals will suffer from it within their lifetime. A hallmark of cancer is the uncontrolled growth of cells, which is normally prevented by a network of control mechanisms that restricts the number of divisions normal cells can do. Cells that are damaged or have reached a certain age are prevented from any further divisions to remove the potential for them becoming cancerous. However, this continuous removal of old and damaged cells comes at a cost. While it avoids the formation of cancerous cells, it also increasingly impedes the regeneration of tissues, which is thought to be a major factor contributing to the ageing process of an individual. Thus, oncogenesis and ageing are opposite but tightly linked forces. My interest in cancer genetics and ageing was one of the key motivations for studying molecular biology and for most of my research up to now. Initially, the medical aspects of cancer were my main interest. I spent several months in a human genetics laboratory where I worked directly with cancerous tissue. However, this work, although interesting, left me rather unsatisfied. Little was known about the details of cancer development in human cells and the studies I was doing felt rather like shots in the dark. Shortly afterwards I did a course in a lab that was interested in genomic stability in baker's yeast. Here I experienced that the understanding of the molecular details of DNA metabolism in yeast was far advanced in comparison to human cells. I was able to do simple experiments that allowed me to understand why the genetic information became unstable. In humans this lack of genomic stability is one of the key stages that results in transformation of a normal cell into a cancer cell, as it corrodes the complex network of quality control systems that maintains genomic integrity and ensures that cells only divide once it is safe to do so. Motivated by this key feature of the biology of cancer, I went on to investigate how a specific yeast protein called Mph1, which was newly discovered at the time, helps to maintain the genetic information. These studies formed the basis of my Diploma and subsequent PhD training. A similar protein has been identified in humans. It is called FancM since its absence causes Fanconi anemia, a genetic disease associated with a much-elevated risk of cancer. It was exciting to see how investigations of a yeast protein can be of interest for human geneticists.After completing my PhD I decided to study a protein called RecG, a DNA processing enzyme found in almost all species of bacteria. It was thought that RecG, Mph1 and FancM might all have a similar function in DNA metabolism. However, my studies revealed that RecG has an important and previously unknown function. It limits a major cause of genomic instability, one associated with events necessary for the orderly completion of chromosome replication, a fundamental requirement in all organisms. This trigger of genomic instability was unexpected and I am excited by the prospect of dissecting the molecular details. Ultimately, I aim to understand how it might contribute to the development of cancer and ageing. However, my initial studies will continue to exploit more tractable bacterial models so as to build some basic understanding before progressing to the more complex systems operating in higher organisms. As such my studies will also shed light on aspects of genomic instability that enable bacterial pathogens to overcome host defences and to acquire resistance to antibiotics.

癌症正迅速成为人类最常见的死亡原因之一，超过三分之一的人将在有生之年遭受癌症之苦。癌症的一个标志是细胞的不受控制的生长，这通常是通过一系列控制机制来防止的，这些控制机制限制了正常细胞可以进行的分裂数量。受损或已经达到一定年龄的细胞被阻止进一步分裂，以消除它们变得癌症的可能性。然而，不断移除陈旧和受损的细胞是有代价的。虽然它避免了癌细胞的形成，但它也越来越多地阻碍组织的再生，而组织再生被认为是导致个人衰老过程的一个主要因素。因此，致癌和衰老是对立但紧密相连的力量。我对癌症遗传学和衰老的兴趣是学习分子生物学和到目前为止我大部分研究的主要动机之一。起初，癌症的医学方面是我的主要兴趣。我在一家人类遗传学实验室里呆了几个月，在那里我直接与癌症组织打交道。然而，这项工作虽然有趣，但让我相当不满意。人们对人类细胞中癌症发展的细节知之甚少，我所做的研究感觉就像是在黑暗中射击。不久之后，我在实验室上了一门课程，对面包师酵母的基因组稳定性感兴趣。在这里，我体验到，与人类细胞相比，对酵母中DNA新陈代谢的分子细节的了解要先进得多。我能够做一些简单的实验，让我了解为什么基因信息会变得不稳定。在人类中，这种基因组稳定性的缺乏是导致正常细胞转化为癌细胞的关键阶段之一，因为它侵蚀了维持基因组完整性的复杂质量控制系统网络，并确保细胞只有在这样做是安全的情况下才会分裂。在癌症生物学这一关键特征的激励下，我继续研究了一种名为Mph1的特定酵母蛋白是如何帮助维持遗传信息的，这种蛋白是当时新发现的。这些研究构成了我的文凭和随后的博士培训的基础。在人类身上也发现了类似的蛋白质。它被称为FancM，因为它的缺失会导致范可尼贫血，这是一种与癌症风险大大增加有关的遗传病。看到人类遗传学家对酵母蛋白的研究是多么感兴趣，这是一件令人兴奋的事情。在完成博士学位后，我决定研究一种名为RecG的蛋白质，这是一种DNA处理酶，几乎在所有种类的细菌中都存在。有人认为，RecG、Mph1和FancM在DNA代谢中可能都具有相似的功能。然而，我的研究表明，RecG具有一个以前未知的重要功能。它限制了基因组不稳定的一个主要原因，这个原因与有序完成染色体复制所必需的事件有关，而染色体复制是所有生物体的基本要求。这种引发基因组不稳定的因素是意想不到的，我对剖析分子细节的前景感到兴奋。最终，我的目标是了解它可能如何促进癌症和衰老的发展。然而，我的初步研究将继续开发更易处理的细菌模型，以便在进入更复杂的在高等有机体中运行的系统之前建立一些基本的理解。因此，我的研究还将阐明基因组不稳定的方面，这些方面使细菌病原体能够克服宿主防御并获得对抗生素的抗药性。

项目成果

Shaping the landscape of the Escherichia coli chromosome: replication-transcription encounters in cells with an ectopic replication origin.

• DOI: 10.1093/nar/gkv704
• 发表时间: 2015-09-18
• 期刊: Nucleic acids research
• 影响因子: 14.9
• 作者: Ivanova D;Taylor T;Smith SL;Dimude JU;Upton AL;Mehrjouy MM;Skovgaard O;Sherratt DJ;Retkute R;Rudolph CJ
• 通讯作者: Rudolph CJ

The Consequences of Replicating in the Wrong Orientation: Bacterial Chromosome Duplication without an Active Replication Origin.

• DOI: 10.1128/mbio.01294-15
• 发表时间: 2015-11-03
• 期刊: mBio
• 影响因子: 6.4
• 作者: Dimude JU;Stockum A;Midgley-Smith SL;Upton AL;Foster HA;Khan A;Saunders NJ;Retkute R;Rudolph CJ
• 通讯作者: Rudolph CJ

Origins Left, Right, and Centre: Increasing the Number of Initiation Sites in the Escherichia coli Chromosome.

• DOI: 10.3390/genes9080376
• 发表时间: 2018-07-27
• 期刊: Genes
• 影响因子: 3.5
• 作者: Dimude JU;Stein M;Andrzejewska EE;Khalifa MS;Gajdosova A;Retkute R;Skovgaard O;Rudolph CJ
• 通讯作者: Rudolph CJ

Replication Termination: Containing Fork Fusion-Mediated Pathologies in Escherichia coli.

• DOI: 10.3390/genes7080040
• 发表时间: 2016-07-25
• 期刊: Genes
• 影响因子: 3.5
• 作者: Dimude JU;Midgley-Smith SL;Stein M;Rudolph CJ
• 通讯作者: Rudolph CJ

Chromosomal over-replication in Escherichia coli recG cells is triggered by replication fork fusion and amplified if replichore symmetry is disturbed.

• DOI: 10.1093/nar/gky566
• 发表时间: 2018-09-06
• 期刊: Nucleic acids research
• 影响因子: 14.9
• 作者: Midgley-Smith SL;Dimude JU;Taylor T;Forrester NM;Upton AL;Lloyd RG;Rudolph CJ
• 通讯作者: Rudolph CJ