Before a cell can divide to generate two daughter cells it must first duplicate the information held in its genome. This process of DNA replication is essential for all dividing cells (required during development, growth, tissue repair and homeostasis) but it is also risky, as during DNA replication mistakes can occur that result in mutations. The formation of mutation underlies the development and progression of cancer and other disorders. It is now becoming clear that information that regulates the usage of the genome is also contained within the chromatin, a complex of DNA and protein that acts to package and regulate the genetic material.
This chromatin structure must therefore be accurately copied at the same time as the DNA is replicated, as alterations to this information (the “epigenome”) may also result in deregulation of cell function and cause disease.
The enzymatic process used to copy the DNA sequence is well understood, but we lack an understanding of how this process is regulated in order to ensure its accuracy. Furthermore, we are only now beginning to grasp the complexity of chromatin structures and to envisage mechanisms for their accurate duplication.
The aim of my research programme is to understand how the processes of genome and epigenome replication are controlled within space and time in the mammalian cell nucleus. This control is likely to be vital in reducing the occurrence of mutations, and its failure will likely result in the acquisition of harmful changes to the genome and epigenome. We have a particular interest in so called “replication factories” which are the locations in the nucleus where the DNA is copied and the chromatin assembled after replication. We have recently been focussing on the key replication factor PCNA (proliferating cell nuclear antigen), a protein which recruits and coordinates many replication enzymes within these factories.
We use a wide variety of experimental strategies to pursue our aims. Protein purification and other screening methods are used to identify the components of factories and then molecular biology and advanced microscopy techniques allow us to assess the function, location and dynamic activities of these components. We have used super-resolution microscopy and FRET (Förster resonance energy transfer) methodologies to analyse replication factory structure in fine detail, and are developing methods to analyse how the three dimensional organisation of the nucleus affects DNA and chromatin replication.