How do tissues withstand stretching for hours or even days? A study published in the journal Nature Physics has found an unexpected answer: the cells radically reorganize their internal structure and, in the process, release their nuclei from a protective keratin network, one of the main components of the cytoskeleton that gives cells their shape and mechanical strength.
Although it has long been known that keratin protects tissues from major deformations, it was not clear exactly how tissues respond to prolonged stretching. The study reveals that tissues adapt to sustained mechanical forces, a process that ultimately pushes the cell nuclei out of the surrounding keratin cage.
"One of the most intriguing questions our study raises is whether this release process ultimately protects the nucleus or makes it more vulnerable," says Xavier Trepat, professor at the Department of Biomedicine at the Faculty of Medicine and Health Sciences of the University of Barcelona, co-leader of the study and head of the Integrative Cell and Tissue Dynamics group at the Institute for Bioengineering of Catalonia (IBEC).
"On the one hand, the removal of the keratin cage could expose the nucleus more directly to mechanical forces. On the other hand, and although it may seem contradictory, disconnecting the nucleus from a cytoskeletal network under high tension could protect it by preventing the transmission of force," explains Trepat, who is a member of the CIBER Area for Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN). "Further studies are necessary to understand which of these effects predominates and to examine how the nuclei respond to prolonged mechanical stress."
Just as engineers typically reinforce bridges and buildings to withstand repeated loads, the study shows that cells have developed a fairly similar strategy: they continuously rebuild their internal structure to maintain tissue strength against everyday mechanical forces.
