Two competing orientation patterns explain experimentally observed anomalies in growing actin networks

• Verfasst von: Weichsel, Julian [VerfasserIn]
• Verfasst von: Schwarz, Ulrich S. [VerfasserIn]
• Titel: Two competing orientation patterns explain experimentally observed anomalies in growing actin networks
• Verf.angabe: Julian Weichsel and Ulrich S. Schwarz
• Umfang: 6 S.
• Fussnoten: Gesehen am 08.12.2017
• Titel Quelle: Enthalten in: National Academy of Sciences (Washington, DC): Proceedings of the National Academy of Sciences of the United States of America
• Jahr Quelle: 2010
• Band/Heft Quelle: 107(2010), 14, S. 6304-6309
• ISSN Quelle: 1091-6490
• DOI: doi:10.1073/pnas.0913730107
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1566177871

Abstract

The lamellipodium of migrating animal cells protrudes by directed polymerization of a branched actin network. The underlying mechanisms of filament growth, branching, and capping can be studied in in vitro assays. However, conflicting results have been reported for the force-velocity relation of such actin networks, namely both convex and concave shapes as well as history dependencies. Here we model branching as a reaction that is independent of the number of existing filaments, in contrast to capping, which is assumed to be proportional to the number of existing filaments. Using both stochastic network simulations and deterministic rate equations, we show that such a description naturally leads to the stability of two qualitatively different stationary states of the system, namely a ± 35° and a +70/0/-70° orientation pattern. Changes in network growth velocity induce a transition between these two patterns. For sufficiently different protrusion efficiency of the two network architectures, this leads to hysteresis in the growth velocity of actin networks under force. Dependent on the history of the system, convex and concave regimes are obtained for the force-velocity relation. Thus a simple generic model can explain the experimentally observed anomalies, with far reaching consequences for cell migration.