Salk scientists solve longstanding biological mystery of DNA organization

Stretched out, the DNA from all the cells in our body would reach Pluto. So how does each tiny cell pack a two-meter length of DNA into its nucleus, which is just one-thousandth of a millimeter across? The answer to this daunting biological riddle is central to understanding how the three-dimensional organization of DNA in the nucleus influences our biology. Associate Professor Clodagh O’Shea, first author Horng Ou and collaborators have provided an unprecedented view of the 3D structure of human chromatin—the combination of DNA and proteins—in the nucleus of living human cells. In the tour de force study, the Salk researchers identified a novel DNA dye that, when paired with advanced microscopy in a combined technology called ChromEMT, allows highly detailed visualization of chromatin structure in cells in the resting and mitotic (dividing) stages. By revealing nuclear chromatin structure in living cells, the work may help rewrite the textbook model of DNA organization and even change how we approach treatments for disease.