Dresden 2009 – scientific programme

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BP: Fachverband Biologische Physik

BP 13: Cell Migration

BP 13.7: Talk

Wednesday, March 25, 2009, 12:30–12:45, ZEU 260

Growing Actin Networks Form Lamellipodium and Lamellum by Self-Organization — •Florian Huber, Björn Stuhrmann, and Josef Käs — Universität Leipzig, Linnestr. 5, 04103 Leipzig, Germany

Cell migration is associated with the dynamic protrusion of a thin actin-based cytoskeletal extension at the cell front. This extension has been shown to consist of two different substructures, the lamellipodium and the lamellum, which differ in their kinetic and kinematic properties as well as their molecular composition. While the formation of the lamellipodium is increasingly well understood, organizational principles underlying the emergence of the lamellum are just beginning to be unraveled. We developed a 2D Monte-Carlo simulation and an analytical description that include chemical reaction kinetics, actin monomer diffusion, and filament transport to investigate the formation of growing actin networks in migrating cells. We demonstrate the system*s ability to form two distinct networks by self-organization. We find a characteristic transition in filament lengths and a distinct maximum of depolymerization, both within the leading 1*2 microns of the cell, in agreement with experimental data. We investigate the complex interplay between ADF/cofilin and tropomyosin and propose a mechanism that leads to spatial separation of, respectively, ADF/cofilin- or tropomyosin-dominated compartments. Tropomyosin is found to play an important role in stabilizing the lamellar actin network.. Furthermore, the influence of filament severing and annealing on the network properties is explored. We contribute to a fundamental understanding of how cells organize their molecular components to achieve movement.