Turning off “junk DNA” may free stem cells to become neurons

Monday, July 13, 2020

For every cell in the body there comes a time when it must decide what it wants to do for the rest of its life. In an article published in the journal PNAS, National Institutes of Health researchers report for the first time that ancient viral genes that were once considered “junk DNA” may play a role in this process. The article describes a series of preclinical experiments that showed how some human endogenous retrovirus (HERV-K) genes inscribed into chromosomes 12 and 19 may help control the differentiation, or maturation, of human stem cells into the trillions of neurons that are wired into our nervous systems. The experiments were performed by researchers in a lab led by Avindra Nath, M.D., clinical director, at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS).

Over the course of evolution, the human genome has absorbed thousands of human endogenous retrovirus genes. As a result, nearly eight percent of the DNA that lines our chromosomes includes remnants of these genes. Although once thought to be inactive, or “junk”, recent studies have shown that these genes may be involved in human embryonic development, the growth of some tumors, and nerve damage during multiple sclerosis. Previously, researchers in Dr. Nath’s lab showed that amyotrophic lateral sclerosis (ALS) may be linked to activation of the HERV-K gene. In this study, led by Tongguang (David) Wang, M.D., Ph.D., staff scientist at NINDS, the team showed that deactivation of the gene may free stem cells to become neurons.