Force chains lead to long range percolation of forces produced by myosin motors in a disordered cytoskeleton network

Myosin motors produce contractile forces in the actin cytoskeleton of animal cells and are responsible for cell shape changes and locomotion. Myosin generated forces percolate through a disordered elastic crosslinked actin network mediating mechanical interactions between distant myosin motors. Long-range Myosin-myosin interactions can produce energetically favorable ordered structures of myosin in the form of stacks, which are observed in non-muscle cells. We model myosin motors as force dipoles embedded in a random fiber network with linear elastic elements that have both bending and stretching moduli. This model captures the disordered nature of the cytoskeletal network and its nonlinear and anisotropic elastic properties. Minimizing the network elastic energy generated by two motors separated over a distance in the fiber network, we discovered favorable spatial configurations of myosin motors. These optimal configurations reveal force chains and strain clusters that show long range force transmission when compared to a corresponding linear elastic medium. Further, analyzing local network bond orientation can show preferential alignment of fibers. Finally, we predict how the mechanical interactions change with distance and orientation of myosin and network density.