Ancient viruses embedded in our DNA help switch genes on and off, study finds
The DNA that humans acquired from ancient viruses plays a key role in switching on parts of our genetic code on and deactivated, revealed a new study.
Almost half of the human genome consists of segments called transposable elements (TES), also known as “Jump genes” because they can jump around the genome. Some of these There are remains of ancient viruses which have anchored in the genomes of our ancestors and have been transmitted over millions of years.
For decades after the discovery of TES, scientists assumed that they were used no useful objective – that they were “undesirable” DNA. But this new study adds to the evidence of assembly that this description was far from correct.
Far from being fossils without function, these ostensibly dormant stretches of our DNA could be crucial in the regulation of gene expression, in particular during early development, suggests research. Scientists published their conclusions on July 18 in the journal Scientific advances.
“Our genome was sequenced a long time ago, but the function of many of its parts remains unknown”, co-author of the study Hiromi Nakao-InoueResearch coordinator at the Institute of Advanced Study of Human Biology of the University of Kyoto, said in a press release. “We think that transposable elements play an important role in the evolution of the genome, and their meaning should become clearer because the research continues to progress.”
Not so junky after all
The you were deemed “undesirable” because they seemed not relevant for the creation of proteins – the molecules which build cells and maintain them on the move. While genes carry plans for proteins, these repetitive and transposable elements have long been rejected as “non -functional” DNA.
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However, in recent years, evidence has started to accumulate that these repetitive parts of our genomes play a role in the regulation of genes. For example, their Codes are often used to do without coding RNAa molecule that can act on other genes to differentiate cells And regulate the growth of embryos.
A more detailed study of the transposable elements was also made possible by Crispr. The famous gene publishing tool allowed scientists to look at how you influence the Chromatin structure – the mixture of DNA and protein from which chromosomes are made – and Jump the activity of the genes of an embryo After fertilization.
Scientists behind the new research focused on a specific family of and called sea11. The family belongs to a greater class of and which entered the genomes of the primate about 40 million years ago.
The researchers classified the sequences within the MER11 family according to their evolving relationships with each other. This produced four sea subgroups11_G1 (the oldest) at sea11_G4 (the youngest).
To see what effects these have on cells, they have inserted nearly 7,000 of the sequences in cells in laboratory dishes. The sequences, taken from humans and other primates, were placed inside stem cells and neural cells at an early stage, whose gene activity was then measured.
Their results have shown that the youngest members of the MER11 – MER11_G4 – had a strong capacity to activate genes. They were equipped with “unique transcription factor binding sites”, which are DNA patterns that are essential to development and act as reception pads for proteins that control the expression of genes.
Subtile variations in the MER11_G4 sequences also existed between humans, chimpanzees and macaques, with variations modifying the regulatory effect of species sequences.
“The study underlines how much it remains to learn from the genome sequence”, ” Cristina TufarelliA geneticist at the University University Research Center of the University of Leicester, who was not involved in the study, told Live Science. “Especially with regard to transposon rehearsals in the form of viruses whose variety between and within families has been largely neglected.”
She added that work will open several ways for a future investigation. “The approach could be applied to any transposable element with the potential to help acquire more in-depth knowledge of other elements with potential regulatory functions,” she said.
Tufarelli added that future experiences could involve removing certain parts of ETS with CRISPR to help disentangle their roles in regulating the expression of health and sickness genes.
