UTSW Scientists Discover Ancient Viral Remnants in the Human Genome

New research from the Children’s Medical Center Research Institute at UT Southwestern (CRI), published in Science, reveals that ancient viral remnants in the human genome are activated during pregnancy and following significant blood loss to boost blood cell production. This finding is a significant step toward understanding the role of so-called “junk DNA” in humans.

Sean J. Morrison, Ph.D., Director of CRI and Howard Hughes Medical Institute Investigator, along with first author Julia Phan, Ph.D., aimed to uncover how hematopoietic (blood-forming) stem cells—usually infrequently dividing—become active during pregnancy and after blood loss. Their study showed that retrotransposons were activated in stem cells from pregnant mice, but not in nonpregnant ones.

Retrotransposons are ancient viral sequences embedded in our genome, often labeled as “junk DNA” because they do not code for proteins involved in cellular functions. These sequences replicate using an enzyme called reverse transcriptase, similar to the process used by the human immunodeficiency virus (HIV).

Learn more