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AKB: Biologische Physik

AKB 8: Cell Motility: Neuronal Growth

AKB 8.3: Vortrag

Dienstag, 28. März 2006, 10:45–11:00, ZEU 260

Quantifying the Dynamic Actin Gel and its Active Forces in Neuronal Growth — •Timo Betz, Daniel Koch, Daryl Lim, Miriam Wisehart, Allen Ehrlicher, and Josef Käs — Institut for Soft Matter Physics, University of Leipzig, Linnestr. 5, 04103 Leipzig, Germany

The neuronal wiring of a developing organism is performed by the highly motile structures at the tips of growing neurites, called growth cones. The locomotion of these structures is largely driven by the dynamics of an active actin gel in the lamellipodium, similar to other motile cells. We developed an experimental assay to measure the neuronal actin dynamics by tracking prominent structures in the lamellipodium of GFP-actin transfected neuronal cells. This is used to quantify the active movement of the actin gel in the neuronal growth cones, a process called retrograde flow. It is currently believed that the growth cone exerts forces onto the substrate by coupling the retrograde flow of the active actin gel to the substrate. To further investigate this, we additionally measure the substrate forces directly by detecting the deformation of an elastic substrate, allowing us to correlate retrograde flow with traction forces. With this assay we have established a method to simultaneously measure all the forces and dynamics necessary to test recently proposed theoretical models for cell motility. We present a detailed analysis of the actin dynamics, substrate forces and local friction constants used by neuronal growth cones as they migrate through the body to correctly wire complex neuronal networks during development.