Title: Origin of soft glassy rheology in the cytoskeleton,
Abstract: Dynamically crosslinked semiflexible biopolymers such as the actin
cytoskeleton govern the mechanical behavior of living cells. Semiflexible
biopolymers stiffen nonlinearly in response to mechanical loads, whereas the
crosslinker dynamics allow for stress relaxation over time. Here we show,
through rheology and theoretical modeling, that the combined nonlinearity in
time and stress leads to an unexpectedly slow stress relaxation, similar to the
dynamics of disordered systems close to the glass transition. Our work suggests
that transient crosslinking combined with internal stress is the microscopic
origin for the universal glassy dynamics as frequently observed in cellular
mechanics.