Regulation of Motions of Myosin Motors in the Actin Cortex

Active transport driven by molecular motors in the cytoskeleton plays an important role in various cellular processes. It has been hypothesized that motions of myosin motors in the cortex are determined by the architecture of the cortex. However, the effects of dynamic, force-dependent behaviors of cytoskeletal components on myosin motors remain elusive despite their potential importance. In this study, we employed an agent-based computational model to study motions of myosin in the cell cortex. The model accounts for possible governing factors, including force-dependent walking of motors and the turnover of cross-linkers and F-actin. We found that motions of motors can be suppressed due to three reasons. Motors can slow down significantly either by local force generation or global force transmission between motors. It is also possible F-actin aggregation prevents motors from consistently walking. However, F-actin turnover can recover motor motility in all three cases by inducing force relaxation on motors and cross-linkers. Our results shed light on how myosin motions are regulated by many factors in vivo.