Microrheology Of Actin-Vimentin-Microtubule Composite Cytoskeletal Networks

Mechanics of the cytoskeleton is known to be responsible for maintaining cell mechanical integrity and determining cellular functions. We develop a method that enables us to reconstruct a three-component in­ vitro network composed of intermediate filaments (vimentin filaments), microtubules and F-actin filaments, which are three fundamental cytoskeletal components. This composition is more physiologically relevant compared with any of the previously reconstituted cytoskeletal networks, which are composed of one or two components only. We investigate the structure and mechanical properties of this multicomponent cytoskeletal network using a combination of several microscopies and microrheology. We show that vimentin filaments couple the other cytoskeletal filaments together by introducing steric constraints between cytoskeletal polymers; these inter­network interactions extend the composite network elastic behavior to a longer time scale, prolong the network relaxation time, and facilitate the stress propagation within the network. These findings are helpful to deepen our understanding of the mechanical role vimentin plays in regulating cellular activities.