title: Two-tiered coupling between flowing actin and immobilized N-cadherin/catenin complexes in neuronal growth cones.
abstract: Neuronal growth cones move forward by dynamically connecting actin-based motility to substrate adhesion, but the mechanisms at the individual molecular level remain unclear. We cultured primary neurons on N-cadherin-coated micropatterned substrates, and imaged adhesion and cytoskeletal proteins at the ventral surface of growth cones using single particle tracking combined to photoactivated localization microscopy (sptPALM). We demonstrate transient interactions in the second time scale between flowing actin filaments and immobilized N-cadherin/catenin complexes, translating into a local reduction of the actin retrograde flow. Normal actin flow on micropatterns was rescued by expression of a dominant negative N-cadherin construct competing for the coupling between actin and endogenous N-cadherin. Fluorescence recovery after photobleaching (FRAP) experiments confirmed the differential kinetics of actin and N-cadherin, and further revealed a 20% actin population confined at N-cadherin micropatterns, contributing to local actin accumulation. Computer simulations with relevant kinetic parameters modeled N-cadherin and actin turnover well, validating this mechanism. Such a combination of short- and long-lived interactions between the motile actin network and spatially restricted adhesive complexes represents a two-tiered clutch mechanism likely to sustain dynamic environment sensing and provide the force necessary for growth cone migration.
authors.affiliation: Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique (CNRS), University of Bordeaux, 33077 Bordeaux, France; CYTOO SA, Minatec, 38040 Grenoble, France;
authors.forename: Mikael
authors.initials: M
authors.lastname: Garcia
authors.affiliation: Cell Polarity, Migration, and Cancer Unit, CNRS, Unité de Recherche Associée 2582, Institut Pasteur, 75724 Paris Cedex 15, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Leduc
authors.affiliation: Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique (CNRS), University of Bordeaux, 33077 Bordeaux, France;
authors.forename: Matthieu
authors.initials: M
authors.lastname: Lagardère
authors.affiliation: CYTOO SA, Minatec, 38040 Grenoble, France;
authors.forename: Amélie
authors.initials: A
authors.lastname: Argento
authors.affiliation: Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique (CNRS), University of Bordeaux, 33077 Bordeaux, France;
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Sibarita
authors.affiliation: Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique (CNRS), University of Bordeaux, 33077 Bordeaux, France; olivier.thoumine@u-bordeaux.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Thoumine
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001696:Biomechanical Phenomena; D015820:Cadherins / Q000378:metabolism*; D051177:Catenins / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology*; D017931:DNA Primers / Q000235:genetics; D004622:Embryo, Mammalian / Q000166:cytology; D005453:Fluorescence; D036681:Fluorescence Recovery After Photobleaching; D020439:Growth Cones / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology*; D007150:Immunohistochemistry; D056004:Molecular Dynamics Simulation; D046912:Multiprotein Complexes / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D051381:Rats; D013997:Time Factors
chemical_list: D000199:Actins; D015820:Cadherins; D051177:Catenins; D017931:DNA Primers; D046912:Multiprotein Complexes
keywords: N-cadherin adhesion; actin flow; growth cone; micropatterned substrates; single-molecule tracking