WORCESTER, MA A retrovirus called HERV-H, which inserted itself into the human genome millions of years ago, may play an important role in pluripotent stem cells, according to a new study published in the journal Retrovirology by scientists at UMass Medical School. Pluripotent stem cells are capable of generating all tissue types, including blood cells, brain cells and heart cells. The discovery, which may help explain how these cells maintain a state of pluripotency and are able to differentiate into many types of cells, could have profound implications for therapies that would use pluripotent stem cells to treat a range of human diseases.
"What we've observed is that a group of endogenous retroviruses called HERV-H is extremely busy in human embryonic stem cells," said Jeremy Luban, MD, the David L. Freelander Memorial Professor in HIV/AIDS Research, professor of molecular medicine and lead author of the study. "In fact, HERV-H is one of the most abundantly expressed genes in pluripotent stem cells and it isn't found in any other cell types."
In the study, Dr. Luban and colleagues describe how RNA from the HERV-H sequence makes up as much as 2 percent of the total RNA found in pluripotent stem cells. The HERV-H sequence is controlled by the same factors that are used to reprogram skin cells into induced pluripotent stem (iPS) cells, a discovery that garnered the 2012 Nobel Prize in Physiology or Medicine. "In other words, HERV-H is a new marker for pluripotency in humans that has the potential to aid in the development of iPS cells and transform current stem cell technology," said Luban.
When a retrovirus infects a cell, it inserts its own genes into the chromosomal DNA of the host cell. As a result, the host cell treats the viral genome as part of its own DNA sequence and begins making the proteins required to assemble new copies of the virus. And because the retrovirus is now part of the host cell's genome, when the cell
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University of Massachusetts Medical School