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BP: Fachverband Biologische Physik

BP 5: Cell Adhesion

BP 5.8: Vortrag

Montag, 26. März 2007, 12:45–13:00, H44

Directed cytoskeletal remodeling in response to integrin activation — •Carina Raupach, Claudia Tanja Mierke, Claus Metzner, and Ben Fabry — Zentrum für medizinische Physik und Technik, Universität Erlangen-Nürnberg

Binding of fibronectin-coated beads to the cell surface has been previously shown to trigger integrin clustering, recruitment of focal adhesion proteins, and directed cytoskeletal (CSK) remodeling (Galbraith et al. JCB (2002)). Moreover, these events have been shown to depend on bead size and bead binding time. To quantify CSK remodeling triggered by integrin activation, we measured the spontaneous motion of fibronectin-coated beads bound to carcinoma cells. We analyzed bead binding times ranging from 15 min to 7 h, and used beads with diameters of 0.5, 1, 2 and 4.5 µm. From the bead trajectories we computed the mean square displacement (MSD) and the persistence of motion, p_φ ∈[−1,1]. For all bead sizes and binding times, the MSD followed a power law, Δ r²(Δ t) = D· Δ t^β+ c, with a motion that was superdiffusive (β > 1) and directionally persistent (p_φ>0 for Δ t > 3 s). Persistence p_φ (for Δ t = 3s) and β decreased monotonically with increasing bead binding time from a highly persistent and nearly ballistic behavior (at 15 min) to a more undirected and random behavior (at 7 h). With increasing bead size, persistence p_φ and β increased monotonically. These data show that directionally persistent CSK remodeling is highly dependent on bead size, and continues, although with declining persistence p_φ, for several hours after the initial integrin receptor activation through bead binding.