DNA flows inside a cell's nucleus in a choreographed line dance, new simulations reveal. The finding is the first large-scale explanation of genetic material moving within a working cell.
DNA flows inside a cell's nucleus in a choreographed line dance, new simulations reveal. The finding is the first large-scale explanation of genetic material moving within a working cell.
"Previous work mostly focused on what was going on at the microscale of DNA," says study co-author Michael Shelley, group leader for biophysical modeling at the Flatiron Institute's Center for Computational Biology in New York City and co-director of the Courant Institute's Applied Mathematics Laboratory at New York University. "People didn't really think about what was going on at the larger scale."
Shelley and colleagues simulated the motions of chromatin, the functional form of DNA inside the nucleus. Chromatin looks like beads on a string, with ball-like clusters of genetic material linked by strands of DNA. The researchers propose that molecular machines along the DNA cause segments of the chromatin to straighten and pull taut. This activity aligns neighboring strands to face the same direction. That alignment, in turn, results in a cascading waltz of genetic material shimmying across the nucleus.
The dancing DNA may play a role in gene expression, replication and remodeling, though the exact effects remain unclear, the researchers reported online October 22 in Proceedings of the National Academy of Sciences.
The findings help explain measurements reported in 2013 by scientists, including Alexandra Zidovska, at Harvard University. Besides previously known small-scale motions of individual genes, the scientists' experiment revealed large regions of chromatin that shifted in unison through a cell's nucleus at a rate of a fraction of a micron every few seconds. The scientists, though, couldn't identify the cause or details of the movement.
