Beta- and Gamma-Cytoplasmic Actins Are Required for Meiosis in Mouse Oocytes1

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 loca...

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Bibliographic Details
Published inBiology of reproduction Vol. 85; no. 5; pp. 1025 - 1039
Main Authors Brockmann, Céline, Huarte, Joachim, Dugina, Vera, Challet, Ludivine, Rey, Emmanuelle, Conne, Béatrice, Swetloff, Adam, Nef, Serge, Chaponnier, Christine, Vassalli, Jean-Dominique
Format Journal Article
LanguageEnglish
Published Society for the Study of Reproduction, Inc 01.11.2011
Subjects
actin
actin isoforms
asymmetric cell division
blastocyst
meiosis
oocyte
polarity
preimplantation development
preimplantation embryo
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Summary: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.
ISSN:0006-3363
1529-7268
DOI:10.1095/biolreprod.111.091736