Science

DNA is constantly under threat of damage; breaks in one or both strands of its double helical structure are associated with many disorders including cancer, premature ageing, infertility, immune deficiencies and neurodegeneration.

Sources of damage arise both in and outside the cell and while most injury is a consequence of natural cellular metabolic processes, external agents such as UV light, ionising radiation or smoking can also disrupt DNA.

To combat DNA damage and allow normal cell function and replication, cells have an array of mechanisms that detect DNA damage and carry out repair. Accurate repair is critical if DNA is to continue coding for the right proteins in the right amount at the right time.

Distinct phases in DNA repair exist when damage occurs. DNA damage ‘sensors’ bind to the injured site, triggering signalling pathways in the cell that promote a variety of responses, each specific to the type of damage. Such responses include halting the cell cycle to allow repair of the damaged DNA or where the damage is too great, entering the cell into programmed cell death (apoptosis). This prevents the carry-over of damaged DNA to, and the possible abnormal function of, daughter cells.