Université Grenoble Alpes, Centre National de la Recherche Scientifique (CNRS), Institut Néel, Grenoble, France, Université Grenoble Alpes, Centre National de la Recherche Scientifique (CNRS), Laboratoire des Technologies de la Microélectronique CEA-LETI, Grenoble, France, Laboratoire PhysicoChimie Curie, Institut Curie Pierre-Gilles de Gennes Institute for Microfluidics, CNRS PSL Research University, Paris, France, Biological Algorithms Group, Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, Germany, Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel

Hippocampal neurons produce in their early stages of growth propagative, actin-rich dynamical structures called actin waves. The directional motion of actin waves from the soma to the tip of neuronal extensions has been associated with net forward growth, and ultimately with the specification of neurites into axon and dendrites. Here, geometrical cues are used to control actin wave dynamics by constraining neurons on adhesive stripes of various widths. A key observable, the average time between the production of consecutive actin waves, or mean inter-wave interval (IWI), was identified. It scales with the neurite width, and more precisely with the width of the proximal segment close to the soma. In addition, the IWI is independent of the total number of neurites. These two results suggest a mechanistic model of actin wave production, by which the material conveyed by actin waves is assembled in the soma until it reaches the threshold leading to the initiation and propagation of a new actin wave. Based on these observations, we formulate a predictive theoretical description of actin wave-driven neuronal growth and polarization, which consistently accounts for different sets of experiments. © 2017 Tomba, Braïni, Bugnicourt, Cohen, Friedrich, Gov and Villard.

Actin wave, Axon, Micropatterns, Modeling, Polarization

actin, animal cell, antibody labeling, Article, axon, cell adhesion, comparative study, controlled study, geometry, growth rate, hippocampal neuronal culture, mouse, nerve elongation, neurite outgrowth, nonhuman, polarization