A new study led by Irene Gallego Romero of the University of Melbourne, Australia, was published in the open access journal on December 8, 2022 PLOS Genetics.
The Papuans, indigenous to the island of New Guinea, owe 5% of their genome to the Denisovans, an extinct group closely related to Neanderthals that people have identified only through their DNA and Sparse remains are known in Siberia and Tibet. To better understand the significance of this genetic contribution, the researchers searched the genomes of 56 Papuans to see whether they carried Denisovan or Neanderthal DNA sequences, and then predicted how those sequences might affect different type of cell function.
Based on the location of the nonhuman sequences, the team found that, in the Papuans, Denisovan DNA — but not Neanderthal DNA — appeared to strongly and consistently affect immune cells and function. Further tests on cell cultures confirmed that the Denisovan DNA sequences successfully modulated nearby genes, up- or down-regulating their expression in ways that might affect how people respond to infection.
The new study shows that Denisovan DNA sequences altered the immune responses of early modern humans living in New Guinea and nearby islands, possibly helping them adapt to the local environment. Further exploring how DNA from extinct human ancestors affects gene expression may be key to understanding the consequences of interbreeding with other groups, the researchers concluded. The results also support the idea that ancient DNA has had a broad impact on shaping the genetic diversity and evolution of modern humans, and may have influenced multiple traits in people who inherited Denisovan and Neanderthal DNA.
Dr Davide Vespasiani, first author, added: “We show that not only Neanderthal but also Denisovan DNA is likely to contribute to gene expression in humans. Further validation will reveal that these effects are predominantly cell type specificity or consistency across cells”
Senior author Dr Irene Gallego Romero concluded: “Until today, some Denisovan DNA has been present in Papuan humans, playing a role in regulating genes related to the immune system. Our study is the first to fully reveal the functional heritage of modern Denisovan DNA in the human genome.”
Source of story:
material provider PLOS. NOTE: Content may be edited for style and length.