Retroviruses have been integrated into our human DNA. A research group at Lund University in Sweden has now identified a structure through which these retroviruses may have an impact on gene expression. This means that they may have played an important role in the development of the human brain, as well as in various neurological disorders.
Retroviruses are an exclusive group of viruses including some which are serious, such as HIV, while others are considered to be not as dangerous. The viruses that were researched by Johan Jakobsson and his colleagues are called endogenous retroviruses (ERV). They have existed in the human genome for millions of years. They can be detected in a part of DNA that was previously considered irrelevant, which analysts have now begun to reevaluate.
Johan Jakobsson said, “The genes that control the production of various proteins in the body represent a smaller proportion of our DNA than endogenous retroviruses. They account for approximately 2%, while retroviruses account for 8-10% of the total genome. If it turns out that they are able to influence the production of proteins, this will provide us with a large new source of information about the human brain.”
This is exactly what the analysts found. They have come to the conclusion that thousands of the retroviruses that have settled themselves in our genome may serve as “docking platforms” for a protein called TRIM28. This protein has the capability to “switch off” not only viruses, but also the basic genes adjacent to them in the DNA helix, allowing the presence of ERV to affect gene expression.
This switching-off mechanism may not behave the same in all people. This makes it a possible tool for evolution. There are studies that indicate a deviating regulation of ERV in several neurological diseases such as bipolar disorder, schizophrenia, and ALS.
Johan Jakobsson said, “Much of what we know about the overall development of the brain comes from the fruit fly, zebrafish and mouse. 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.”