title: Beta- and gamma-cytoplasmic actins are required for meiosis in mouse oocytes.
abstract: In mammals, female meiosis consists of two asymmetric cell divisions, which generate a large haploid oocyte and two small polar bodies. Asymmetric partitioning of the cytoplasm results from migration of the meiotic spindle toward the cortex and requires actin filaments. However, the subcellular localization and the role of the existing two cytoplasmic actin (CYA) isoforms, beta and gamma, have not been characterized. We show that beta- and gamma-CYA are differentially distributed in the maturing oocyte from late metaphase I as well as in preimplantation embryos. Gamma-CYA is preferentially enriched in oocyte cortices and is absent from all cell-cell contact areas from metaphase II until the blastocyst stage. Beta-CYA is enriched in contractile structures, at cytokinesis, at cell-cell contacts, and around the forming blastocoel. Alteration of beta- or gamma-CYA function by isoform-specific antibody microinjection suggests that gamma-CYA holds a major and specific role in the establishment and/or maintenance of asymmetry in meiosis I and in the maintenance of overall cortical integrity. In contrast, beta- and gamma-CYA, together, appear to participate in the formation and the cortical anchorage of the second meiotic spindle in waiting for fertilization. Finally, differences in gamma-CYA expression are amongst the earliest markers of cell fate determination in development.
authors.affiliation: Departments of Genetic Medicine and Development and Pathology and Immunology, University of Geneva Medical School, Geneva, Switzerland.
authors.forename: Céline
authors.initials: C
authors.lastname: Brockmann
authors.forename: Joachim
authors.initials: J
authors.lastname: Huarte
authors.forename: Vera
authors.initials: V
authors.lastname: Dugina
authors.forename: Ludivine
authors.initials: L
authors.lastname: Challet
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Rey
authors.forename: Béatrice
authors.initials: B
authors.lastname: Conne
authors.forename: Adam
authors.initials: A
authors.lastname: Swetloff
authors.forename: Serge
authors.initials: S
authors.lastname: Nef
authors.forename: Christine
authors.initials: C
authors.lastname: Chaponnier
authors.forename: Jean-Dominique
authors.initials: JD
authors.lastname: Vassalli
mesh_terms: D000199:Actins / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D000818:Animals; D000906:Antibodies / Q000008:administration & dosage / Q000276:immunology / Q000494:pharmacology; D002450:Cell Communication / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D016764:Cell Polarity; D002478:Cells, Cultured; D003593:Cytoplasm / Q000502:physiology*; D005260:Female; D008540:Meiosis / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D008845:Microinjections; D023421:Models, Animal; D009865:Oocytes / Q000166:cytology* / Q000502:physiology
chemical_list: D000199:Actins; D000906:Antibodies