Skip to main content

Role of ubiquitin in DNA replication and damage

Principal Supervisor: Dr Aga Gambus - Institute of Cancer and Genomic Sciences

PhD project title: Role of Ubiquitin in DNA replication and damage

University of Registration: Birmingham

Project outline:

Every dividing cell needs to duplicate its genome perfectly before cell division. When mistakes happen during replication they do need to be efficiently repaired by DNA damage repair (DDR) mechanisms. Failure to do so can result in cell death or development of mutations leading to cancer. It is essential therefore to understand the mechanism of eukaryotic DNA replication and DDR, how they are regulated in normal cells, how they misregulation contributes to tumorigenesis and how this misregulation can be exploited in the treatment of cancer. The proposed project is focusing on studying how ubiquitylation regulates chromosomal replication and DDR.

Ubiquitylation is a posttranslational modification of substrate proteins by attachment of one or many ubiquitins (small protein). Ubiquitylation is very flexible and versatile and regulates almost every aspect of cell biology. Not surprisingly it is essential for proper DDR and we have shown that polyubiquitylation is essential for a truly enigmatic stage of DNA replication – its termination (Moreno et al. Science, 2014). This project provides therefore and exciting opportunity to follow up this discovery, use established techniques and unravel new essential regulatory roles for this amazing modification.

DNA replication is such a fundamental biological process that it is incredibly well conserved throughout evolution and DDR processes have been studied in many different model systems. The aim of this project is to carry out our work in the best model system available to answer the biological question in mind. We have expertise in the lab using a cell-free system of Xenopus laevis egg extract as it provides a simpler model system to study DNA replication. We also work with human cell lines and collaborate with groups working with buddying yeast S.cerevisiae and worm C.elenags. We use biochemistry, proteomics but also genomic modifications (CRISPR/Cas9), cell biology techniques and microscopy.

Importantly, enzymes attaching ubiquitin to substrates (ubiquitin ligases) and removing it (deubiquitylating enzymes, DUBs) were shown to be druggable. It is essential therefore to consider studied processes and enzymes as potential targets for cancer therapies. Indeed first drugs affecting ubiquitylation regulating DNA replication are now being tested in clinical trials as future cancer therapies.

BBSRC Strategic Research Priority: Molecules, cells and systems

Techniques that will be undertaken during the project:

The student will work both with human cell lines as well as Xenopus laevis egg extract system and henceforth learn techniques specific for both. It will provide opportunity to carry on proteomic analysis of chromatin bound complexes in egg extract system but also DNA analysis and microscopy in human cell lines.

Contact: Dr Aga Gambus, University of Birmingham