One person’s junk is another’s treasure.
An international team of scientists has found that the strings of “garbage” DNA in the human genome that have previously been written off because there is no useful function are actually quite important at the end.
The work published as a exploration In the magazine Science is progressingfocuses on transposed elements, class DNA sequences that can “jump” through a biological mechanism for copying and placing different places in the genome. These “jumping genes” occupy nearly 50 percent of human DNA; In other organisms, the proportion is even higher.
What researchers from Japan, China, Canada and the United States have discovered that a family of those called Mer11 can greatly affect gene expression and act as “genetic switches” – without actually changing the main DNA.
“Our genome has been sequentially sequenced, but the function of many of its parts remains unknown,” said study co -author Fumitaka Inu of the University of Kyoto in A A statement For the work.
Mer11 sequences are what is known as Long Terminal Repeat (Ltr) Retrotransposons. It is believed that they were derived from an endogenous retrovirus (ERV), which infects the Simic predecessor tens of millions of years ago, abducting the DNA of the cells to which he has invaded to produce copies of his genetic composition, which have never disappeared but are largely remained. To the researchers, at least eight percent of the human genome comes from these retroviruses.
That plus all the other TES that strengthens our genome makes a lot puzzling pile of human scientists to sift. The authors claim that the current methods of classification and appearance of TES are inaccurate, resulting in the DNA sequences are neglected as genetic junk. This inspired them to test their own classification system.
“The correct classification and explanation of LTR specimens is crucial to understanding their evolution, cooperation and potential impact on the host,” the authors wrote in the study.
The system of researchers classifies the sequences of Mer11 based on their evolutionary relationships and how well they are preserved in primitive genomes, according to a statement by researchers. They then divided the Mer11 into four separate subfamates, Mer11_G1 to G4, based on their age.
This allowed the team to compare the subfamily MER11 with what is known as Epigenetic: chemicals that can influence how important proteins function, And as a consequence it affects gene activity. The most important thing is that epigenetic signs should not physically change the DNA of the cell to change the behavior of the cell, such as silence of a gene that must be expressed. The accurate binding of the Mer11 subfamily to the markers is a key step towards revealing the extent of their impact on gene expression.
With this as a springboard, the team tests about 7,000 sequences of Mer11 by people and primates, measures how much it affected gene activity and found that the most jerk subfamily Mer11, G4, has a strong ability to influence gene expression – namely, bearing their own DNA motifs that attract are excluded outside.
“The young Mer11_G4 is associated with a separate set of transcription factors, indicating that this group has acquired various regulatory functions through changes in sequence and contributes to the specification,” said leading author Xun Chen of the Chinese Academy of Sciences.
The consequences are compelling. Although these DNA directions may have begun as “junk”, they have gradually planted their way to playing a role in regulating a gene today – suggesting a huge part of the unknown evolutionary story, to which we only scratch the surface of.
“It is believed that transposable elements play an important role in the evolution of the genome and their importance is expected to become more clear as research continues to progress,” Inue said.
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