Two-tiered coupling between flowing actin and immobilized N-cadherin/catenin complexes in neuronal growth cones
Proc Natl Acad Sci USA. 2015-05-18; 112(22): 6997-7002
DOI: 10.1073/pnas.1423455112
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1. Proc Natl Acad Sci U S A. 2015 Jun 2;112(22):6997-7002. doi:
10.1073/pnas.1423455112. Epub 2015 May 18.
Two-tiered coupling between flowing actin and immobilized N-cadherin/catenin
complexes in neuronal growth cones.
Garcia M(1), Leduc C(2), Lagardère M(3), Argento A(4), Sibarita JB(3), Thoumine
O(5).
Author information:
(1)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;
(2)Cell Polarity, Migration, and Cancer Unit, CNRS, Unité de Recherche Associée
2582, Institut Pasteur, 75724 Paris Cedex 15, France.
(3)Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la
Recherche Scientifique (CNRS), University of Bordeaux, 33077 Bordeaux, France;
(4)CYTOO SA, Minatec, 38040 Grenoble, France;
(5)Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la
Recherche Scientifique (CNRS), University of Bordeaux, 33077 Bordeaux, France;
.
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.