Determining how global genome nucleotide excision repair promotes efficient removal of DNA damage from chromatin

点击翻译按钮获取中文摘要

Contained within each of our cells is the coded information necessary for life. The information is stored in a compartment of the cell called the nucleus which contains a large molecule with a remarkable structure called deoxyribonucleic acid - DNA. The information within the DNA is divided into units called chromosomes which are further subdivided into genes. DNA is packaged into chromatin in order to compact the genetic material in the nucleus and the sum of all the genetic material of an organism is referred to as its genome. It might be anticipated that life's coded information would be extremely stable and resistant to change, since errors in the code could have serious consequences. On the other hand, organisms are able to adapt to changes in their environment by virtue of the genetic variation within the population caused by alterations in the genetic material of individuals. This process is known as evolution. In the human population a lot of genetic variation is the result of 'reshuffling' of the genes during sexual reproduction. However, DNA can also be altered by normal processes operating within the cell, as well as physical or chemical damage from the environment, including ultraviolet radiation from sunlight. The DNA in each of our cells is continuously damaged by such agents. If left unchecked this would quickly erode the genetic information, since copying damaged DNA when cells divide can permanently alter the genetic code - a process called mutation. Over time, a variety of different DNA repair pathways have evolved which serve to prevent this from occuring. Collectively these are fundamental to the stability of the genome. People who inherit defects in the genes controlling these DNA repair pathways are more likely to suffer from certain cancers and other diseases. Our research aims to understand how one of these processes, nucleotide excision repair [NER] operates. People with defects in genes regulating this process suffer highly elevated levels of skin and other cancers. Molecular studies have revealed how defects in different genes involved in the process can result in a number of clinically distinct diseases. Much of our knowledge has come from the study of NER in a variety of different organisms. We study NER in bakers' yeast. Amazingly, the mechanism in yeast is remarkably similar to that in human cells, underlining the fundamental significance of this process. The work described in this proposal aims to help us understand how the NER process is organised in the genome and how lesions are removed from chromatin following UV induced DNA damage. It is emerging that the sensors of DNA damage in chromatin are playing an important role in how DNA repair is regulated in the cell. Research into DNA repair has entered a new phase of discovery, revealing how the various DNA repair mechanisms are controlled in response to DNA damage and how the pathways are integrated with one another. In addition to improving our understanding of the molecular basis of human disease syndromes, novel synthetic genetic interactions between the pathways are identifying new targets for novel and improved cancer treatments. At present our knowledge of how the NER pathway operates in chromatin and how this process is regulated lags behind our knowledge in other repair pathways. The work carried out in this proposal will significantly improve our knowledge in this area providing significant insight for further human studies.