Knotted Networks Form Cellular Safety Nets

T hin bags filled with water aren’t the obvious material for building robust, complex structures. But when it comes to constructing biological tissues, such bags—which biological cells essentially resemble—are what nature has to work with. To provide the necessary mechanical properties, cells’ interiors are reinforced with various biopolymer networks, with each network resisting strain in a different stress regime. NowMarco Pensalfini of the Polytechnic University of Catalonia, Spain, and his colleagues have investigated the dynamics of one of these networks—the so-called intermediate-filament (IF) network—which helps keep the cells in epithelial tissues intact under large deformations [1]. The researchers show that the role of this network as a cellular “safety net” depends on how the filaments tangle together.