The genome's mysterious UCE surveillance system

Genomes are dynamic, rearranging themselves as they function and evolve. Ting Wu's lab studies the parts of the animal genome that resist change. Called ultraconserved elements, or UCEs, these chunks of DNA have been maintained essentially unchanged for 300 million to 500 million years—appearing today exactly as they were when birds, reptiles, and mammals diverged from each other. Since UCEs were discovered in 2004, many ideas about their function and significance have been proposed, and yet they remain a mystery. Wu's group has proposed that the maternal and paternal copies of UCEs undergo a process of side-by-side comparison; when the copies don't match up, the individual's fitness decreases, and the lineage eventually dies out. Thus UCEs may provide stability in the midst of genome change, helping sort good mutations from bad ones. Cancer and other disease cells may grow unchecked in part because they have lost this surveillance function. Someday, Wu imagines, there might be therapies that prevent cancer, and even radiation damage for space travelers, by supporting the work of UCEs in blocking the proliferation of damaged cells. Social media hashtag: #WhatsaUCE.