title: Cdc42 controls the dilation of the exocytotic fusion pore by regulating membrane tension.
abstract: Membrane fusion underlies multiple processes, including exocytosis of hormones and neurotransmitters. Membrane fusion starts with the formation of a narrow fusion pore. Radial expansion of this pore completes the process and allows fast release of secretory compounds, but this step remains poorly understood. Here we show that inhibiting the expression of the small GTPase Cdc42 or preventing its activation with a dominant negative Cdc42 construct in human neuroendocrine cells impaired the release process by compromising fusion pore enlargement. Consequently the mode of vesicle exocytosis was shifted from full-collapse fusion to kiss-and-run. Remarkably, Cdc42-knockdown cells showed reduced membrane tension, and the artificial increase of membrane tension restored fusion pore enlargement. Moreover, inhibiting the motor protein myosin II by blebbistatin decreased membrane tension, as well as fusion pore dilation. We conclude that membrane tension is the driving force for fusion pore dilation and that Cdc42 is a key regulator of this force.
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France Institut National de la Santé et de la Recherche Médicale, U932, Institut Curie, 75005 Paris, France.
authors.forename: Marine
authors.initials: M
authors.lastname: Bretou
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France.
authors.forename: Ouardane
authors.initials: O
authors.lastname: Jouannot
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Fanget
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U932, Institut Curie, 75005 Paris, France.
authors.forename: Paolo
authors.initials: P
authors.lastname: Pierobon
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France.
authors.forename: Nathanaël
authors.initials: N
authors.lastname: Larochette
authors.affiliation: Institut Curie, Paris 75248, France Institut National de la Santé et de la Recherche Médicale, U900, Paris 75248, France Ecole des Mines ParisTech, Fontainebleau, 77300 France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Gestraud
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Guillon
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France.
authors.forename: Valentina
authors.initials: V
authors.lastname: Emiliani
authors.affiliation: Centre National de la Recherche Scientifique/UPR3212, Institut des Neurosciences Cellulaires et Intégratives, Université Strasbourg, 67084 Strasbourg, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Gasman
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Desnos
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U932, Institut Curie, 75005 Paris, France.
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Lennon-Duménil
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Centre National de la Recherche Scientifique, UMR 8250, 75270 Paris Cedex 06, France Francois.Darchen@parisdescartes.fr.
authors.forename: François
authors.initials: F
authors.lastname: Darchen
mesh_terms: D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology*; D006801:Humans; D008561:Membrane Fusion / Q000502:physiology*; D024462:Myosin Type II / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D024462:Myosin Type II; D020764:cdc42 GTP-Binding Protein