Watch the human genome fold itself in four dimensions

Each human cell nucleus is packed with 2 meters of DNA wrapped around 46 chromosomes like a jumble of spaghetti. These “noodles” are in constant motion as they adjust to what the cell needs to do, and these adjustments bring certain genes into contact so they can work together. Now, researchers have visualized this dance at 20-minute intervals, so that they get a 4D rendering: They can see how this 3D structure changes over time. In doing so they have demonstrated how one protein helps orchestrate these movements. By removing and then adding this protein, called cohesin, researchers made specific DNA loops that disappear and then reappear, they report this month in Cell. But cohesin really only affects looping that brings genes on the same chromosome into contact. A second, still-undefined mechanism seems to bring genes from different chromosomes together, the team notes. The changing landscape of loops helps cells quickly change which genes are active. Understanding this dance could help researchers better understand and treat genetic disease.