Symmetry Breaking and Emergence of Directional Flows in Minimal Actomyosin Cortices.

Sven K Vogel, Christian Wölfer, Diego A Ramirez-Diaz, Robert J Flassig, Kai Sundmacher, Petra Schwille

Cells 2020 Jun 09

filter terms:

Cortical actomyosin flows, among other mechanisms, scale up spontaneous symmetry breaking and thus play pivotal roles in cell differentiation, division, and motility. According to many model systems, myosin motor-induced local contractions of initially isotropic actomyosin cortices are nucleation points for generating cortical flows. However, the positive feedback mechanisms by which spontaneous contractions can be amplified towards large-scale directed flows remain mostly speculative. To investigate such a process on spherical surfaces, we reconstituted and confined initially isotropic minimal actomyosin cortices to the interfaces of emulsion droplets. The presence of ATP leads to myosin-induced local contractions that self-organize and amplify into directed large-scale actomyosin flows. By combining our experiments with theory, we found that the feedback mechanism leading to a coordinated directional motion of actomyosin clusters can be described as asymmetric cluster vibrations, caused by intrinsic non-isotropic ATP consumption with spatial confinement. We identified fingerprints of vibrational states as the basis of directed motions by tracking individual actomyosin clusters. These vibrations may represent a generic key driver of directed actomyosin flows under spatial confinement in vitro and in living systems.

Citation

Sven K Vogel, Christian Wölfer, Diego A Ramirez-Diaz, Robert J Flassig, Kai Sundmacher, Petra Schwille. Symmetry Breaking and Emergence of Directional Flows in Minimal Actomyosin Cortices. Cells. 2020 Jun 09;9(6)