The human genome is made up of 23 sets of chromosomes. This is the biological blueprint that makes humans. However, we find that some of our DNA (about 8%) are the remains of ancient viruses that have embedded themselves into our genetic code during the course of human evolution.
These ancient viruses are found in sections of our DNA called translocation elements, also known as “jump genes,” or TE, due to their ability to copy and paste themselves throughout the genome. TES, which accounts for almost half of our genetic material, was once deployed as a sequence “junk” DNA that appears to have no biological function. Now, new research supports the hypothesis that these ancient virus remnants play an important role in the early stages of human development and may be linked to our evolution.
By sequencing the TES, an international team of researchers identified hidden patterns that could be important for gene regulation. The findings were published in Science Advances on July 18th.
“Our genome was sequenced long ago, but many of the functions of that portion remain unknown,” co-author Dr. Fumitaka Inoue, an associate professor of functional genomics at Kyoto University in Japan, said in a statement. “Translocatable elements are thought to play an important role in genome evolution, and its importance is expected to become more clear as research continues to progress.”
There are many benefits to studying how TES activates gene expression. Helps scientists understand role that Sequence It plays with human evolution, uncovers possible links between TE and human diseases, and teaches researchers how to target functional TE in gene therapy, said Xun Chen, a computational biologist and chief investigator of Shanghai immunity and infectious diseases at the Chinese Academy of Sciences.
“We hope that TE, especially ERV (endogenous retroviruses, or ancient viral DNA) will reveal how we become human,” Chen added in an email.
When our primate ancestors are infected with a virus, the sequence of genetic information of the virus is replicated and inserts itself into various locations on the host chromosome.
“Ancient viruses are effective at invading our ancestor genomes, and their remains become a large part of our genome. Our genome has developed many mechanisms to control these ancient viruses and eliminate potentially harmful effects.”
Although in most cases these ancient viruses are inactive and not a cause of concern, research has shown in recent years that some of the translocatable elements may play an important role in human disease. A July 2024 survey examined the possibility of silencing certain TEs to make cancer treatment more effective.
“In the course of evolution, some viruses have been denatured or eliminated, some have been largely suppressed in normal development and physiology, and some have been tamed to be useful in the human genome,” he said, noting that he has been involved in new research. “Although they are simply perceived as harmful, some ancient viruses become part of us and provide raw materials for genomic innovation.”
However, due to their repetitive nature, transposeable elements are notoriously difficult to study and organize. TE sequences are categorized into families and subfamilies based on their function and similarity, but many are poorly documented and classified as “potentially affecting evolutionary and functional analyses.”
The effects of ancient viruses on human development and evolution
The new study focused on a group of TE sequences called MER11 found within the primate genome. By using a new classification system and testing the gene activity of DNA, researchers identified four previously undiscovered subfamilies.
A recently integrated sequence named Mer11_g4 was found to have a strong ability to activate gene expression in human stem cells and early stage neurons. The findings show that this subfamily plays a role in early human development, and “dramatically affects how genes respond to developmental signals or environmental cues,” according to a statement from Kyoto University.
This study also suggests that viral TE was involved in shaping human evolution. By tracking how DNA changes over time, researchers have discovered that subfamilies evolve differently within the genomes of various animals, contributing to biology evolution The result was humans, chimpanzees and macaques.
“Understanding the evolution of our genome is one way to understand why humans are unique,” he said. “It empowers us with tools to understand human biology, human genetic diseases, and human evolution.”
Chen said it is unclear exactly how these TEs are related to the evolutionary process. It is also possible that other TESs that have not yet been identified have played an evolutionary distinct role. process primates, he added.
“This study provides new insights and potential leverage points for understanding the role of TE in shaping the evolution of our genome,” said Dr. Steve Hoffman, a computational biologist on aging in German Jenna, who was not involved in the study. The study also “emphasizes how much we can learn from the type of DNA that we once slandered as molecular freeloaders,” he added in an email.
Hoffman was the lead investigator in a scientific paper that first recorded an almost complete genomic map of the Greenland shark, the world’s longest living vertebrate that can survive to about 400 years. The shark genome was made up of over 70% jump genes, while the human genome is made up of less than 50%. Although the primate genome is different from the shark genome, “this study provides further evidence of the potential impact of TE on genome regulation,” and “a message relevant to all genomic researchers,” Hoffman said.
By investigating how the genome evolved, researchers can determine which DNA sequences remain The same, it was lost in time and recently emerged.
“Taking these sequences into consideration is important in understanding why certain animals often develop diseases that are not,” Hoffman said. “Ultimately, a deeper understanding of genomic regulation will help us discover new therapies and interventions.”
Taylor Nishiori is a freelance journalist based in New York.
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