title: Septins promote F-actin ring formation by crosslinking actin filaments into curved bundles.
abstract: Animal cell cytokinesis requires a contractile ring of crosslinked actin filaments and myosin motors. How contractile rings form and are stabilized in dividing cells remains unclear. We address this problem by focusing on septins, highly conserved proteins in eukaryotes whose precise contribution to cytokinesis remains elusive. We use the cleavage of the Drosophila melanogaster embryo as a model system, where contractile actin rings drive constriction of invaginating membranes to produce an epithelium in a manner akin to cell division. In vivo functional studies show that septins are required for generating curved and tightly packed actin filament networks. In vitro reconstitution assays show that septins alone bundle actin filaments into rings, accounting for the defects in actin ring formation in septin mutants. The bundling and bending activities are conserved for human septins, and highlight unique functions of septins in the organization of contractile actomyosin rings.
authors.affiliation: Institut de Biologie du Développement de Marseille, CNRS UMR 7288, Aix-Marseille Université, 13288 Marseille, France.
authors.forename: Manos
authors.initials: M
authors.lastname: Mavrakis
authors.affiliation: Institut de Biologie du Développement de Marseille, CNRS UMR 7288, Aix-Marseille Université, 13288 Marseille, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Azou-Gros
authors.affiliation: 1] FOM Institute AMOLF, 1098 XG Amsterdam, The Netherlands [2].
authors.forename: Feng-Ching
authors.initials: FC
authors.lastname: Tsai
authors.affiliation: 1] FOM Institute AMOLF, 1098 XG Amsterdam, The Netherlands [2].
authors.forename: José
authors.initials: J
authors.lastname: Alvarado
authors.affiliation: 1] Institut Curie, CNRS UMR 168, 75231 Paris, France [2].
authors.forename: Aurélie
authors.initials: A
authors.lastname: Bertin
authors.affiliation: Institut de Biologie du Développement de Marseille, CNRS UMR 7288, Aix-Marseille Université, 13288 Marseille, France.
authors.forename: Francois
authors.initials: F
authors.lastname: Iv
authors.affiliation: Institut Fresnel, CNRS UMR 7249, Aix-Marseille Université, Ecole Centrale Marseille, 13397 Marseille, France.
authors.forename: Alla
authors.initials: A
authors.lastname: Kress
authors.affiliation: Institut Fresnel, CNRS UMR 7249, Aix-Marseille Université, Ecole Centrale Marseille, 13397 Marseille, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Brasselet
authors.affiliation: FOM Institute AMOLF, 1098 XG Amsterdam, The Netherlands.
authors.forename: Gijsje H
authors.initials: GH
authors.lastname: Koenderink
authors.affiliation: Institut de Biologie du Développement de Marseille, CNRS UMR 7288, Aix-Marseille Université, 13288 Marseille, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lecuit
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism; D000818:Animals; D002455:Cell Division; D002970:Cleavage Stage, Ovum / Q000378:metabolism; D048749:Cytokinesis / Q000502:physiology; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics; D006801:Humans; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009218:Myosins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D058112:Septins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D020409:Molecular Motor Proteins; D000205:Actomyosin; D058112:Septins; D009218:Myosins