The switch, called CTCF, is a protein that binds to DNA and forms a loop. When the loop is formed, it prevents RNA polymerase from accessing the gene, and the gene is turned off. When the loop is untied, RNA polymerase can access the gene, and the gene is turned on.
The researchers found that CTCF forms loops by binding to two different sites on DNA. One site is located near the gene that CTCF is regulating, and the other site is located further away. When CTCF binds to both sites, it forms a loop that brings the two sites together. This loop prevents RNA polymerase from accessing the gene, and the gene is turned off.
When the CTCF protein is removed from the DNA, the loop is untied, and RNA polymerase can access the gene. This allows the gene to be turned on.
The researchers say that the CTCF switch is a powerful tool for controlling gene expression. They believe that this switch could be used to develop new drugs and therapies that target specific genes.
"The CTCF protein is a key player in the regulation of gene expression," said Dr. Lars Herold, who led the study. "By understanding how CTCF works, we can develop new ways to control gene expression and treat diseases."
The study was published in the journal *Nature Genetics*.
Source: Max Planck Institute of Molecular Genetics
