Mostly Biomathematics Lunchtime Seminar
How friction controls actomyosin contraction on micropatterned surfaces
Speaker: Mariya Savinov, Courant
Location: Warren Weaver Hall 1314
Date: Tuesday, March 5, 2024, 12:45 p.m.
Actomyosin network self-organization and contraction are central for cell organization, shape, and motility. The dynamics emerge from a balance of active local stresses, network deformation, external global friction stresses, and geometry. To investigate the relative importance of these components, our collaborators conducted in vitro experiments with reconstituted actomyosin networks on micropatterned surfaces. These systems self-organize such that myosin motors rapidly condense into a few spots, then initiate a contraction process which compacts the whole actin network. Remarkably, the compaction point is insensitive to the myosin distribution, centered in homogeneous domains and biased to more adhesive regions for heterogeneous patterns.
To explain this result, we model the actomyosin network as a 2D deformable viscoelastic cable-network material with active contractile stresses generated by advected myosin spots and external friction forces from adhesions. Through analysis and simulation, we find that our model reproduces key experimental results. Notably, the model explains why the friction, not myosin, pattern determines the compaction point. Though contraction is local and randomly initialized, the external friction pattern and network connectedness lead to robust global behaviors on the cellular level.