Time varying mechanical response of cytoskeletal networks

Actin filaments and microtubules are critical components of the cytoskeleton, a composite network of filamentous polymers and regulatory proteins. The synergistic interplay of networks of actin filaments and microtubules and their continuous disassembly and reassembly via active de/re-polymerization play a crucial role in a wide range of mechanical properties and processes, including cell stiffness, shape change, and motility. While in-vitro actin networks have been intensely investigated over the past two decades due to their promise for understanding cell mechanics and designing smart materials, questions remain as to how the composite nature of the cytoskeleton and de/re-polymerization kinetics of individual filaments impact the collective, time-varying mechanics of cytoskeletal networks. This talk will discuss an integrated approach consisting of theory and experiments, that seeks to address these questions. In particular, we will describe the mechanical response of composites made of interconnected networks of semiflexible and stiff filaments, time-varying responses of these networks, and how they can be explained by mathematical models that couple the time-evolution of filament lengths with rigidity percolation theory. Our results provide insights into mechanisms that enable cells to exhibit a myriad of mechanical properties and can inform the general principles underlying the mechanics of a large class of dynamic systems and biomaterials of current interest.