DNA Repair Gone Wrong Leads to Cascade of Chromosome Rearrangements

Homologous Recombination Can Cause More Breaks As It Fixes Them

The traditional view of cancer is that a cell has to sustain a series of hits to its DNA before its defenses break down enough for it to turn cancerous. But cancer researchers have also found that cells can experience very rapid and widespread DNA damage that could quickly lead to cancer or developmental defects.

Now researchers at the University of California, Davis, have found that these complex chromosomal rearrangements can be triggered in a single event when a process used to repair DNA breaks, homologous recombination, goes wrong. The work is published Aug. 10 in the journal Cell.

New Steps in the Meiosis Chromosome Dance

Where would we be without meiosis and recombination? For a start, none of us sexually reproducing organisms would be here, because that’s how sperm and eggs are made. And when meiosis doesn’t work properly, it can lead to infertility, miscarriage, birth defects and developmental disorders.

Neil Hunter’s laboratory at the UC Davis College of Biological Sciences is teasing out the complex details of how meiosis works. In a new paper published online Jan. 6 in the journal Science, Hunter’s group describes new key players in meiosis, proteins called SUMO and ubiquitin and molecular machines called proteasomes. Ubiquitin is already well-known as a small protein that “tags” other proteins to be destroyed by proteasomes (wood chippers for proteins). SUMO is a close relative of ubiquitin.