Roles of Catch Bond Dynamics in Cytoskeletal Networks

The cytoskeleton plays an important role in various physiological processes. For example, actin networks which consist of F-actins inter-connected via cross-linking proteins are known to serve as a scaffolding structure in cells. The cross-linking proteins can be dissociated from F-actins as either a slip bond or a catch bond. We recently demonstrated that an actin network comprised of weak catch bonds exhibits higher yielding stress/strain than those with strong slip bonds. In this study, we employed an agent-based computational model to understand better how and when weak bonds can make a stronger material by exploring parametric spaces consisting of F-actin length, actin concentration, and the density and kinetics of cross-linking proteins. Further, we investigated how catch bonds affect the propagation of cracks formed in the network. It was found that weak catch bonds unbind from low-stress areas and eventually move to higher-stress areas, whereas slip bonds remain trapped in their initial positions. This difference leads to different yielding stress/strain and distinct crack propagation. Our study provides further insights into understanding potential roles of catch and slip bonds of various proteins in physiological processes.