Key result
Simulations show compliant crosslinkers enable molecular motors to stiffen actin networks ~100-fold vs incompliant linkers.
Why the study?
The mechanisms by which molecular motors induce strain stiffening in actin networks with different crosslink compliances were not fully understood.
Finite element simulations demonstrate that compliant crosslinkers in actin networks allow significant strain stiffening by molecular motors compared to rigid crosslinkers.
We have studied the elastic response of actin networks with both compliant and rigid crosslinks by modeling molecular motors as force dipoles. Our finite element simulations show that for compliant crosslinkers such as filamin A, the network can be stiffened by two orders of magnitude while stiffening achieved with incompliant linkers such as scruin is significantly smaller, typically a factor of two, in excellent agreement with recent experiments. We show that the differences arise from the fact that the motors are able to stretch the compliant crosslinks to the fullest possible extent, which in turn causes to the deformation of the filaments. With increasing applied strain, the filaments further deform leading to a stiffened elastic response. When the crosslinks are incompliant, the contractile forces due to motors do not alter the network morphology in a significant manner and hence only small stiffening is observed.
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Chen et al. (2010) studied this question. Compliant crosslinkers (e.g., filamin A) vs. Incompliant linkers (e.g., scruin) was evaluated on Elastic response and strain stiffening. Finite element simulations showed that actin networks with compliant crosslinkers can be stiffened by two orders of magnitude by molecular motors, compared to a factor of two with incompliant linkers.
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