For the first time, images have been obtained and the structure of the LINE-1 retrotransposon, a remnant of an ancient virus found in human DNA, has been revealed. It is believed that its activation in cells can lead to cancer, dementia and autoimmune diseases. A study by scientists from Harvard Medical School and ROME Therapeutics was published in the journal Nature.
The function of 98% of human DNA is unknown because it contains no active genes. For example, retrotransposons (remnants of ancient viruses) were found in this part of the genome. Human DNA contains approximately half a million copies of the LINE-1 retrotransposon. In a new study, scientists have obtained their first high-resolution images and structural details. They describe it as “an ancient genetic parasite.”
Most copies of LINE-1 are damaged, but about a hundred can potentially become active. A healthy body has mechanisms to suppress retrotransposons. However, research suggests that their activation may be a cause of autoimmune diseases and cancer in humans. Once activated, human cells begin producing the virus’ proteins, using its DNA as instructions. One of these proteins, LINE-1 ORF2 (L1 ORF2p), can cause new mutations in human DNA.
The LINE-1 ORF2p protein acts as reverse transcriptase, an enzyme found in retroviruses, including HIV. Its discovery allowed the development of drugs that suppress the activity of the virus in the body. Similarly, defining the structure of LINE-1 could help develop drugs against autoimmune diseases, cancer and neurodegeneration, the authors say.
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