A Tale of Cytoskeletal Teamwork

At the core of all living organisms are cells, the basic building blocks of life. To survive and function, they must endure mechanical stresses while still performing essential processes such as division and migration. In our own bodies, cells are continually stretched and compressed as we breathe, our hearts beat, and as forces are applied to and by muscles and joints with every step we take. To withstand these forces while maintaining their function, cells rely on the cytoskeleton, a dynamic network composed of three distinct types of protein filaments: actin, microtubules and intermediate filaments. When the cytoskeleton is disrupted by genetic defects, cells can no longer withstand mechanical stress effectively, which can result in various diseases and developmental disorders. For example, mutations in intermediate filaments are linked with conditions such as muscular dystrophies and certain skin disorders, where cells are unable to cope with mechanical strain. Seemingly paradoxically, the cytoskeleton provides cells with elastic mechanical strength, while its ability to actively remodel gives rise to behaviours commonly seen in liquids, such as flowing and deforming over time, enabling essential processes like spreading, migration and division. These properties arise from the complex interplay between cytoskeletal filaments, molecular motors, and cross-linking proteins, which together enable cells to finely tune their mechanical responses. This combination of elastic solidity and liquid-like flow is known as viscoelasticity, a property that allows cells to change shape, adapt to their mechanical environment, and perform dynamic functions. Understanding how cells regulate their viscoelastic properties is key to revealing how they maintain their integrity under stress while remaining flexible enough to grow, move, and divide. In this light, we can think of the cell as a cabinet of mechanical curiosities, where the cytoskeleton, motors, and cross-links interact in finely tuned ways to generate this remarkable mechanical versatility.