Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 17: Posters: Physics of Cells

BP 17.22: Poster

Wednesday, March 28, 2012, 17:30–19:30, Poster A

When Folding does not Imply Pullout: Different Modes of Growth Cone Collapse in NG 108-15 Cells — Philipp Rauch¹, •Paul Heine¹, Barbara Göttgens², and Josef Käs¹ — ¹Institute of Experimental Physics I, University of Leipzig, Germany — ²Institute of Biology, University of Leipzig, Germany

Neuronal pathfinding is crucial for the proper wiring of the central and peripheral nervous system. A growth cone at the tip of every neurite detects and follows multiple guidance cues initiating directional changes, outgrowth, or neurite retraction. However, when focusing on cytoskeletal retraction mechanisms it is rarely considered that even partial retractions of the neurite appear excessive in cases where outgrowth is merely supposed to locally cease or stall.

We evaluated cytoskeletal dynamics of transiently transfected NG108-15 growth cones using fluorescence time lapse microscopy and could identify an alternative mode of growth cone collapse leading to a controlled halt of neurite extension without retraction. Our findings show that lateral movement and folding of actin bundles confine microtubule extension and limit their expansion. This process stands in stark contrast to neurite retraction where collapsing actin structures buckle microtubules. The flexure of these stiff polymers most likely generates considerable forces on the remaining adhesion sites, which inevitably leads to their disintegration and subsequent neurite retraction. Altogether the described mechanisms elucidate neuronal growth regulation by closing the gap between full retraction and small scale fluctuations.