Kinesin-driven active cytoskeletal composite restructuring.

Abstract

The cytoskeleton is an intricate dynamic network that enables vital processes in the cell such as mitosis, movement, and growth. It is composed of protein filaments including semi-flexible actin filaments and rigid microtubules, as well as motor proteins, such as kinesin. The versatile restructurability of the cytoskeleton makes it highly intriguing for designing materials that combine tunability, flexibility, and resilience. Applications can span from soft tissue repair to biodegradable plastics and rubbers. Here, we create actin-microtubule composites, driven by kinesin motors, and adapted by different types of cross-linkers. We observe a range of restructuring of the composites, from formation of homogeneous clusters to heterogeneous threadlike networks. We quantify dynamics of our active composites by using particle image velocimetry (PIV) on time series videos of fluorescently labeled actin and microtubules, and by performing single particle tracking (SPT) on fluorescently labeled NeutrAvidin. Additionally, by imaging spherical hydrogels in the networks, then measuring the deformation of the spheres, we are able to measure forces generated by actin-microtubule composites being reconfigured by kinesin motors.