Here’s an interesting factoid about our genomes: If you stretched out the DNA in a single cell, which is only a few millionths of an inch wide, it would span more than six feet. And another: DNA folding is a dynamic process that changes over time. Scientists have been trying to understand how DNA folds itself up so efficiently, and a recent post on the NIH Director’s Blog highlights new research illustrating how the human genome folds inside the cell’s nucleus, as well as how DNA folding affects gene regulation. The research team created this delightful video that demonstrates the principles involved using origami art.
Researchers have been working to determine how cells regulate gene expression for nearly as long as we’ve known about DNA. How, for example, do nerve cells know to turn off only nerve cell genes and turn off bone cell genes? DNA folding loops are part of the answer. This research team, which published their findings in a paper in Cell yesterday, found that the number of loops is much lower than expected. There are only 10,000 loops instead of the predicted millions, and they form on/off switches in DNA. As explained in the blog post:
[The] paper in Cell adds fascinating details to that map, and it confirms that DNA loops appear to play a crucial role in gene regulation. The researchers found that many stretches of DNA with the potential to fold into loops have genes located at one end and, at the other end, novel genetic switches. When a loop forms, placing a hidden switch in contact with a once-distant gene, the gene is turned on or off. In fact, the mapping work uncovered thousands of these “secret” switches within the genome—information that may provide valuable new clues for understanding cancer and many other complex, common diseases.