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Emergent Active Mechanical Behaviour of the Actomyosin Cell Cortex

Final Report Summary - ACTMECH (Emergent Active Mechanical Behaviour of the Actomyosin Cell Cortex)

This ERC project concerned an investigation of the active and large-scale active mechanical properties
of the actomyosin cell cortex. We have studied how the actomyosin cytoskeleton behaves at scales relevant for cells and tissues, and we investigate how the emergent large-scale behaviours are influenced by molecules. The project was divided into three objectives, (1) actomyosin cortex dynamics forecasting, (2) actin binding proteins and emergent mechanical behaviours, (3) filament alignment in compressive flow and contractile ring formation. We have made significant advances in all objectives and achieved almost all of our goals, by tracking of positions and trajectories of all myosin foci, by providing a physical basis for the formation of pulsatory myosin foci patterns, by characterizing the state of local actin filament in connection to compressive flow, by introducing a novel technique to decipher the biochemical reaction networks that underlie actomyosin cortex homeostasis, and by performing a screen to analyze large-scale actomyosin cortex dynamics phenotypes foci. The biggest achievement of the project was the discovery that the actomyosin cortex can actively generate torques for rotatory chiral flow, and that these chiral rotatory flows are utilized in the four-to-six-cell-stage Caenorhabditis elegans embryo for establishing the embryo’s left-right body axis. Taken together, this ERC grant has provided a significantly improved basis for understanding emergent and cell scale active mechanical behaviors of the actomyosin cytoskeleton.