A team of scientists have discovered that an invasion of viruses into the human genome millions of years ago altered the way genes turn on and off in human embryonic stem cells. This theory was first proposed in the 1950s by Barbara McClintock who believed that sequences of genetic material, such as viruses, can override the “control elements” that regulate genes. Using new sequencing technologies, the team of scientists was able to confirm McClintock’s hypothesis, showing that specific types of viruses inserted themselves into the human genome millions of years ago, dramatically changing the gene regulatory network in human stem cells.
Furthermore, the study showed that by “comparing the genomes of mouse with human… the binding sites for gene regulatory factors are very often not in the same place between the two species… the sites are imbedded within a class of DNA sequences called ‘transposable’ elements because of their ability to move to new places in the genome.” It is these elements within the DNA sequence that is believed to be the “evolutionary remnants of viral genomes…carrying binding sites for regulatory elements to new locations.” These changes, induced by the hijacking virus, had the potential to create major changes in the organism which are believed to have played a prominent role “in the evolution of humans from their predecessors.”
This breakthrough will allow stem cell research, and DNA decoding, to progress in leaps and bounds, and help us to understand the fundamental differences in DNA between us and our closest relatives. The virus factor may rewrite what we know about evolutionary biology, and offer insight into the genetic leap between species, as well as a better understanding of the genetic computation of stem cells, aiding the “development of regenerative medicine for diseases such as Parkinson's disease and leukaemia.”
Image: "Viral DNA" by EMSL on Flickr courtesy of Creative Commons Licensing.