title: Formin-2 is required for spindle migration and for the late steps of cytokinesis in mouse oocytes.
abstract: Female meiotic divisions in higher organisms are asymmetric and lead to the formation of a large oocyte and small polar bodies. These asymmetric divisions are due to eccentric spindle positioning which, in the mouse, requires actin filaments. Recently Formin-2, a straight actin filaments nucleator, has been proposed to control spindle positioning, chromosome segregation as well as first polar body extrusion in mouse oocytes. We reexamine here the possible role of Formin-2 during mouse meiotic maturation by live videomicroscopy. We show that Formin-2 controls first meiotic spindle migration to the cortex but not chromosome congression or segregation. We also show that the lack of first polar body extrusion in fmn2(-/-) oocytes is not due to a lack of cortical differentiation or central spindle formation but to a defect in the late steps of cytokinesis. Indeed, Survivin, a component of the passenger protein complex, is correctly localized on the central spindle at anaphase in fmn2(-/-) oocytes. We show here that attempts of cytokinesis in these oocytes abort due to phospho-myosin II mislocalization.
authors.affiliation: Equipe Divisions Méiotiques Chez la Souris, UMR7622, CNRS, Université Pierre et Marie Curie-Paris 6, Bat C, 5e, 9 Quai Saint Bernard 75005, Paris, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Dumont
authors.forename: Karine
authors.initials: K
authors.lastname: Million
authors.forename: Kelsey
authors.initials: K
authors.lastname: Sunderland
authors.forename: Pascale
authors.initials: P
authors.lastname: Rassinier
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Lim
authors.forename: Benjamin
authors.initials: B
authors.lastname: Leader
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Verlhac
mesh_terms: D000818:Animals; D002875:Chromosomes; D048749:Cytokinesis / Q000502:physiology*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009865:Oocytes / Q000166:cytology*; D008941:Spindle Apparatus
chemical_list: D009419:Nerve Tissue Proteins