DNA endgames

摘要

If it is not repaired efficiently, damage to DNA double strands can have dire consequences for both the cell and the organism. Given the gravity of this situation, cells use two pathways to start the process. In human cells, the two strands of DNA that make up each of our chromosomes break several times a day, either during normal cellular metabolism or following exposure to DNA-damaging agents. Efficient repair of such damage is crucial for restoring the integrity of the genome, and also for preventing premature termination of a process that occurs during meiotic cell division to ensure the genetic diversity of our progeny. Studies in bacteria have shed light on how double-strand breaks are processed for mending, but uncertainty remains over many pivotal aspects of DNA repair in eukaryotic organisms (yeast, plants and animals). Three studies, including one by Mimitou and Symington1 on page 770 of this issue, unlock some of the mysteries of the initiating steps in eukaryotic DNA repair.