title: Actin Filaments Regulate Exocytosis at the Hair Cell Ribbon Synapse.
abstract: Exocytosis at the inner hair cell ribbon synapse is achieved through the functional coupling between calcium channels and glutamate-filled synaptic vesicles. Using membrane capacitance measurements, we investigated whether the actin network regulates the exocytosis of synaptic vesicles at the mouse auditory hair cell. Our results suggest that actin network disruption increases exocytosis and that actin filaments may spatially organize a subfraction of synaptic vesicles with respect to the calcium channels. Significance statement: Inner hair cells (IHCs), the auditory sensory cells of the cochlea, release glutamate onto the afferent auditory nerve fibers to encode sound stimulation. To achieve this task, the IHC relies on the recruitment of glutamate-filled vesicles that can be located in close vicinity to the calcium channels or more remotely from them. The molecular determinants responsible for organizing these vesicle pools are not fully identified. Using pharmacological tools in combination with membrane capacitance measurements, we show that actin filament disruption increases exocytosis in IHCs and that actin filaments most likely position a fraction of vesicles away from the calcium channels.
authors.affiliation: Inserm, Unité Mixte de Recherche 1051, Institute for Neurosciences of Montpellier, 34295 Montpellier Cedex 5, France, and Université Montpellier, 34090 Montpellier, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Guillet
authors.affiliation: Inserm, Unité Mixte de Recherche 1051, Institute for Neurosciences of Montpellier, 34295 Montpellier Cedex 5, France, and Université Montpellier, 34090 Montpellier, France.
authors.forename: Gaston
authors.initials: G
authors.lastname: Sendin
authors.affiliation: Inserm, Unité Mixte de Recherche 1051, Institute for Neurosciences of Montpellier, 34295 Montpellier Cedex 5, France, and Université Montpellier, 34090 Montpellier, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Bourien
authors.affiliation: Inserm, Unité Mixte de Recherche 1051, Institute for Neurosciences of Montpellier, 34295 Montpellier Cedex 5, France, and Université Montpellier, 34090 Montpellier, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Puel
authors.affiliation: Inserm, Unité Mixte de Recherche 1051, Institute for Neurosciences of Montpellier, 34295 Montpellier Cedex 5, France, and Université Montpellier, 34090 Montpellier, France regis.nouvian@inserm.fr.
authors.forename: Régis
authors.identifier: http://orcid.org/0000-0002-0901-4666
authors.initials: R
authors.lastname: Nouvian
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D005089:Exocytosis / Q000502:physiology*; D005260:Female; D006199:Hair Cells, Auditory, Inner / Q000378:metabolism*; D008297:Male; D051379:Mice; D013569:Synapses / Q000378:metabolism*
keywords: cochlea; membrane capacitance; patch-clamp; synaptic release