Two studies by two separate teams, both published last month in the journal Cell, suggest that a protein believed to be crucial to forming long-term memories is the evolutionary remnant of an infection that spread during the early days of four-legged species.
Researchers contend that information stored within these viral cells became incorporated into our genetic code, where it evolved into the activity-regulated cytoskeleton-associated (Arc) protein over the subsequent 400 million years.
The new research shows that when a synapse in the brain fires, the Arc protein copies instructions onto RNA coding molecules and packages the genetic material within virus-like capsules that travel between neurons.
Elissa Pastuzyn, a postdoctoral fellow at the University of Utah and the lead author of one of the studies, told science and technology publication Alphr that her team was shocked to discover just how important the Arc protein is:
“We went into this line of research knowing that Arc was special in many ways, but when we discovered that Arc was able to mediate cell-to-cell transport of RNA, we were floored. No other non-viral protein that we know of acts in this way.”
It may sound a bit odd that a virus could be responsible for such vital pieces of our genetic code, but in actuality, it’s not all that uncommon. A study published in 2016 revealed that between 40 and 80 percent of the human genome is the result of an archaic viral invasion.
“While we think that virus infections and outbreaks are a bad thing (and of course they are), these bouts of infection also provide new source material for evolution to create new genes that ultimately become beneficial for the organism,” Dr. Jason Shepard, a member of Pastuzyn’s team, told Alphr.