A cartoon of a section of chromatin in the nucleus with replication origins in three different states.

John Diffley : Chromosome Replication Laboratory

We are studying how cells copy their DNA and finding out how mistakes in this process lead to cancer.

Every time a cell divides it must copy (replicate) all its DNA and divide it equally into the two new cells. The cell’s DNA must be copied precisely once before it divides, otherwise each new cell will end up with the wrong amount, leading to loss or duplication of crucial genetic information.

Furthermore, mistakes in DNA replication can cause errors, known as mutations, to accumulate. Mutations can kill cells or stop them from dividing when they are needed. Alternatively, they may lead to cells dividing out of control, forming a tumour.

We have discovered many of the mechanisms that regulate this process, ensuring that DNA is accurately copied just once every time a cell divides. To do this, we use a range of methods to study the molecular ‘machines’ that copy DNA in yeast and human cells. Recently we have developed a way of using these machines to copy DNA in a test tube. This is giving us an unprecedented view of this fascinating and essential process.

By finding out the exact sequence of events involved in DNA replication, we will shed light on how normal cells divide to keep the body healthy. And we are also revealing what goes wrong when cells divide out of control as cancer develops.