LUND, Sweden, Jan. 12 (UPI) -- Scientists at Lund University have determined how retroviruses may have affected gene expression and brain development over millions of years.
Retroviruses are a group of viruses made up of both harmful and apparently harmless viruses. Retroviruses have been incorporated into human DNA over millions of years, now making up 10 percent of the human genome.
A team of researchers at Lund University, led by Johan Jakobsson, studied endogenous retroviruses, or ERV, and found that these ERV may play a more important role in gene expression than previously thought.
"The genes that control the production of various proteins in the body represent a smaller proportion of our DNA than endogenous retroviruses," Jakobsson said in a press release. "They account for approximately 2 percent, while retroviruses account for 8 - 10 percent of the total genome. If it turns out that they are able to influence the production of proteins, this will provide us with a huge new source of information about the human brain."
The team has uncovered several thousand retroviruses in the human genome that serve as what they call "docking platforms" for the TRIM28 protein, which can turn off viruses and the standard genes near them in the DNA helix. This allows for ERV to affect gene expression, according to researchers.
The switching activity of TRIM28 varies from person to person, which makes it a possible cause of neurological diseases. Studies have shown there is an altered regulation of ERV in diseases like ALS, schizophrenia and bipolar disorder.
"Much of what we know about the overall development of the brain comes from the fruit fly, zebrafish and mouse," Jakobsson said. "However, if endogenous retroviruses affect brain function, and we have our own set of these ERV, the mechanisms they affect may have contributed to the development of the human brain."
The study was published in Cell Reports.