Avalanches in simulations of branched actomyosin networks with the Arp2/3 complex*

Actomyosin networks are ubiquitous in biology. They provide structure to cells and are involved in cell movement, growth, and division. The dynamics of actomyosin networks are active processes and are greatly influenced by actin binding-proteins (ABPs). These ABPs include both motor proteins (non-muscle myosin IIA heavy chain (NMIIA)) and cross-linker proteins (α-actinin). Another important ABP, the Arp2/3 complex, nucleates branched filaments thereby influencing the topology of the network. In this work, we simulate the spatiotemporal configurations of actomyosin networks with and without the Arp2/3 complex. The simulations show that the branched actomyosin networks that include the Arp2/3 complex exhibit sporadic convulsive movements, which we call avalanches, that release built-up stress in the network. We then identify and characterize these avalanches. The characteristics of these avalanches observed in the simulations are consistent with the recent experimental observation of “cytoquakes”.