title: Nanoscale segregation of actin nucleation and elongation factors determines dendritic spine protrusion.
abstract: Actin dynamics drive morphological remodeling of neuronal dendritic spines and changes in synaptic transmission. Yet, the spatiotemporal coordination of actin regulators in spines is unknown. Using single protein tracking and super-resolution imaging, we revealed the nanoscale organization and dynamics of branched F-actin regulators in spines. Branched F-actin nucleation occurs at the PSD vicinity, while elongation occurs at the tip of finger-like protrusions. This spatial segregation differs from lamellipodia where both branched F-actin nucleation and elongation occur at protrusion tips. The PSD is a persistent confinement zone for IRSp53 and the WAVE complex, an activator of the Arp2/3 complex. In contrast, filament elongators like VASP and formin-like protein-2 move outwards from the PSD with protrusion tips. Accordingly, Arp2/3 complexes associated with F-actin are immobile and surround the PSD. Arp2/3 and Rac1 GTPase converge to the PSD, respectively, by cytosolic and free-diffusion on the membrane. Enhanced Rac1 activation and Shank3 over-expression, both associated with spine enlargement, induce delocalization of the WAVE complex from the PSD. Thus, the specific localization of branched F-actin regulators in spines might be reorganized during spine morphological remodeling often associated with synaptic plasticity.
authors.affiliation: Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France.
authors.forename: Anaël
authors.initials: A
authors.lastname: Chazeau
authors.affiliation: Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France.
authors.forename: Amine
authors.initials: A
authors.lastname: Mehidi
authors.affiliation: Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France.
authors.forename: Deepak
authors.initials: D
authors.lastname: Nair
authors.affiliation: CNRS UPR3082, Laboratoire d'Enzymologie et Biochimie Structurales, Gif-sur-Yvette Cedex, France.
authors.forename: Jérémie J
authors.initials: JJ
authors.lastname: Gautier
authors.affiliation: University Bordeaux, LP2N, Talence, France CNRS & Institut d'Optique, LP2N, Talence, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Leduc
authors.affiliation: Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Chamma
authors.affiliation: Division of Molecular Cell Biology, Zoological Institute, Technical University Braunschweig, Braunschweig, Germany.
authors.forename: Frieda
authors.initials: F
authors.lastname: Kage
authors.affiliation: Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France.
authors.forename: Adel
authors.initials: A
authors.lastname: Kechkar
authors.affiliation: Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Thoumine
authors.affiliation: Division of Molecular Cell Biology, Zoological Institute, Technical University Braunschweig, Braunschweig, Germany Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Klemens
authors.initials: K
authors.lastname: Rottner
authors.affiliation: Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Choquet
authors.affiliation: CNRS UPR3082, Laboratoire d'Enzymologie et Biochimie Structurales, Gif-sur-Yvette Cedex, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Gautreau
authors.affiliation: Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Sibarita
authors.affiliation: Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France gregory.giannone@u-bordeaux2.fr.
authors.forename: Grégory
authors.initials: G
authors.lastname: Giannone
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D049229:Dendritic Spines / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D000080865:Formins; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000378:metabolism; D016133:Polymerase Chain Reaction; D057907:Post-Synaptic Density / Q000378:metabolism*; D011506:Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D018709:Statistics, Nonparametric; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; C503229:Baiap2 protein, rat; C476208:FMNL2 protein, human; D000080865:Formins; D009419:Nerve Tissue Proteins; D011506:Proteins
keywords: branched F‐actin regulators; dendritic spine; postsynaptic density; single protein tracking; super‐resolution microscopy