Mutations in the MED12 protein are a marker for FG syndrome (also know as OpitzKaveggia syndrome), a rare genetic disorder that leads to abnormalities throughout the body and varying degrees of physical and neurological problems. "This clearly shows how activating ncRNAs can influence disease development, an idea that has been gaining evidence in the scientific literature," Shiekhattar said. To confirm that ncRNA-a works with Mediator to form a loop in DNA, the researchers used a technique called chromosome conformation capture (3C) to gain a better understanding of the three-dimensional structure of chromosomes. Their results show how Mediator gets a foothold of sorts on the portion of DNA that encodes the ncRNA-a, and twists the DNA to form a loop.
"The looping mechanism serves to physically bring together a distant enhancer element with the start site of the targeted gene, allowing Mediator to recruit the proteins responsible for reading the gene to the location," Shiekhattar said. "It is at least one answer to how these classical enhancer elements function while being physically distant from their target genes."
|Contact: Greg Lester|
The Wistar Institute