Reviewed by Kate Anderton, B.Sc. (Editor) Jan 24 2020
"Jumping genes" -- bits of DNA that can move from one spot in the genome to another -- are well-known for increasing genetic diversity over the long course of evolution. Now, new research at Washington University School of Medicine in St. Louis indicates that such genes, also called transposable elements, play another, more surprising role: stabilizing the 3D folding patterns of the DNA molecule inside the cell's nucleus.
The study appears Jan. 24 in the journal Genome Biology .
The DNA molecule inside the nucleus of any human cell is more than six feet long. To fit into such a small space, it must fold into precise loops that also govern how genes are turned on or off. It might seem counterintuitive that bits of DNA that randomly move about the genome can provide stability to these folding patterns. Indeed, the discovery contradicts a long-held assumption that the precise order of letters in the DNA sequence always dictates the broader structure of the DNA molecule.
In places where the larger 3D folding of the genome is the same between mice and humans, you expect the sequence of the letters of the DNA anchoring that shape to be conserved there as well. But that's not what we found, at least not in the portions of the genome that in the past have been called 'junk DNA.'" Ting Wang, PhD, senior author, the Sanford C. and Karen P. Loewentheil Distinguished Professor of Medicine
Studying DNA folding in mouse and human blood cells, the researchers found that in many regions where the folding patterns of DNA are conserved through evolution, the genetic sequence of the DNA letters establishing these folds is not. It is ever so slightly displaced. But this changing sequence, a genetic turnover, doesn't cause problems. Because the structure largely stays the same, the function presumably does, too, so nothing of importance changes.
"We were surprised to find that some young transposable elements serve to maintain old structures," said first author Mayank N.K. Choudhary, a doctoral student in Wang's lab. "The specific sequence may be different, but the function stays the same. And we see that this has happened multiple times over the past 80 million years, when the common ancestors of mice and humans first diverged from one another." Related Stories
Also in Industry News
How to decide whether or not to start treatment for prostate cancer?
Analysis of the SARS-CoV-2 proteome via visual tools
$65m investment increases British Patient Capital’s exposure to life sciences and health technology