Ibec Seminar. Ulrich Schwarz.
Modelling optogenetic control of cell contractility
Ulrich Schwarz, Heidelberg University
Animal cells are highly dynamic and continuously generate force, for example for mechanosensing, cell division, cell migration, morphogenesis and regeneration. Their main force generators are non-muscle myosin II molecular motors that slide actin filaments past one another. We first discuss how myosin II minifilaments dynamically assemble on demand and how this system can be controlled by optogenetics. The resulting deformations and forces can be predicted with continuum models for active solids, which are solved with the finite element method and verified experimentally with traction force microscopy. Next, we use active gel theory combined with van der Waals theory for myosin II molecules to demonstrate that cell contractility is sufficient to explain cell migration and that optogenetics can be used to initiate, revert and stop migration. We then turn to multiple cells and show for a cell doublet how the neighboring cell actively responds to the contraction of an optogenetically activated cell. We finally introduce a finite element framework for cellularized active solids that allows us to study mechanosensitive wave propagation in optogenetically activated cell layers.
