Regensburg 2007 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 23: Cell Motility and Migration (in vitro and in vivo)
BP 23.6: Vortrag
Donnerstag, 29. März 2007, 15:30–15:45, H43
Investigation of Filopodial Mechanics and Dynamics — •Brian Gentry1, Michel Gögler1, Marie-France Carlier2, and Josef Käs1 — 1Universität Leipzig, Linnestr. 5, Leipzig, Germany — 2CNRS, LEBS, 1 Avenue de la Terrasse, Gif-sur-Yvette, France
The actin cytoskeleton is a complex system that dynamically reorganizes its structure to produce forces that drive the leading edge of a cell membrane outward. Filopodia emerge from local reorganization of the dense lamellipodial filament network. Stiff bundles are essential to produce protrusive forces, so we study their mechanical properties. We directly measure actin bundle bending stiffness in vitro, providing information about crosslinker and bundle characteristics. Formation of long, unbranched bundles also requires that fiber ends be protected from capping. Formin is an end-binding molecule which is capable of nucleating and driving the polymerization of actin polymers in vivo, remaining bound simultaneously to both fiber and substrate. We are studying formin in a controlled, reconstituted system to help elucidate its precise functions as considered in recent models. Both experiments use a state-of-the-art laser tweezer to track the position of a bead attached to an actin filament bundle, allowing us to measure critical buckling and motor-driven forces. The formin measurements are the first for an end-tracking motor and will lend new insight into the underlying dynamics of its operation. Our setup allows us to take a novel approach to the study of filopodial component's properties-bundles which provide stiffness and a molecular engine which produces adequate forces such that protrusion can occur.