A network of protein fibres helps to prevent the all-important organelle from being bent out of shape.

A cell protects its nucleus by swaddling it in a minuscule wrapping of soft but resilient protein fibres.

Cells sometimes need to squeeze through tight spaces, but such contortions can squash a cell’s precious nucleus, which holds much of its DNA. To investigate how cells safeguard their nuclei, Robert Goldman at Northwestern University in Chicago, Illinois, Paul Janmey at the University of Pennsylvania in Philadelphia and their colleagues examined the role of the cellular protein vimentin, which forms fibres that stiffen under stress.

The team’s observations of mouse cells showed a cage of vimentin around the nucleus. However, that cage was missing in cells that lacked the vimentin gene, and the nuclei of these cells were much more likely to rupture during movement than the nuclei of normal cells.

When cells without vimentin wriggled through a narrow passageway, the cells’ DNA showed 50% more damage than did the DNA of cells that contained vimentin. The results show that vimentin has a hand in determining the fate of a cell and its genome.