Paris Postdoc Seminar – Dennis Wörthmüller

Invited by theI nstitut Jacques Monod, Dennis Wörthmüller will present a Paris Postdoc Seminar on the theme:

When Actin Meets Curvature: Modeling Free-Standing Cell Protrusions

Abstract:

Cell shape changes are largely controlled by the actin cytoskeleton, a dynamic filament network beneath the plasma membrane. Some cell types can form extended free-standing protrusions that are not supported by an extracellular substrate, and whose initiation is thought to rely on proteins that modulate actin dynamics through sensitivity to membrane curvature. I will present a theoretical model for a free-standing viscous actin network growing on a corrugated membrane, which couples active-gel mechanics, membrane deformation, and the recruitment of curvature-sensitive actin nucleators. The model shows that uniform actin polymerization stabilizes membrane shape, whereas curvature-dependent nucleation can render the membrane linearly unstable and drive spontaneous deformations with a well-defined wavelength that could initiate protrusions. To explore these processes beyond the linear regime, we develop a finite-element framework that captures nonlinear deformations of fluid and elastic layers, opening the way to realistic simulations of actin-driven membrane shape changes.