Viruses and their hosts have been at war for more than a billion years…Although the earliest antiviral systems have long since vanished, researchers may now have recovered remnants of one of them embedded, like a fossil, in human cells.
A protein called Drosha, which helps to control gene regulation in vertebrates, also tackles viruses, researchers report[ed]. They suggest that Drosha and the family of enzymes, called RNAse III, it belongs to were the original virus fighters in a single-celled ancestor of animals and plants.
“You can see the footprint of RNAse III in the defense systems through all kingdoms of life,” says Benjamin tenOever, a virologist at Icahn School of Medicine at Mount Sinai in New York….
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[I]n 2010, tenOever witnessed an odd phenomenon: Drosha appeared to leave the nucleus of human cells whenever a virus invaded….To test the hypothesis that Drosha leaves the nucleus to combat viruses in vertebrates, the researchers infected cells that had been genetically engineered to lack Drosha with a virus. They found that the viruses replicated faster in these cells. The team then inserted Drosha from bacteria into fish, human and plant cells. The protein seemed to stunt the replication of viruses, suggesting that this function dates back to an ancient ancestor of all the groups.
[Read the full study here]
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