Ancient viral DNA switched off a brain-development gene in chimpanzees
A study in Science Advances finds that the retrovirus PTERV1 inserted DNA into ancestral chimpanzees, silencing LINC00662, a gene active in human brain development. In lab-grown brain organoids, switching off the gene reduced activity in genes linked to neuron development and connections; removing the viral insertion from chimpanzee stem cells restored LINC00662 activity.
Bottom line — The Lund University team says PTERV1 may help explain differences in human and chimpanzee brain development, but not their full scale or cause.
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Science News reports that PTERV1 DNA appears at 158 locations in the chimpanzee genome and is absent in humans.
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Phys.org says the viral sequences are silenced through methylation, a chemical process that can switch genes off.
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The infection is thought to have affected ancestral African apes between 5 million and 7 million years ago, according to Science News.
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Science News quotes evolutionary geneticist Ravinder Kanda cautioning that the findings do not establish how much the insertion shaped chimpanzee brains.
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ScienceAlert reports that the researchers do not know all of LINC00662’s roles or what its reduced activity means for chimpanzees as a whole.
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The Lund University researchers plan to investigate whether other viral remnants influenced brain evolution, according to Phys.org.