1 Section of Molecular Pathology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, Københavns Universitet2 Department of Biomedical Sciences, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, Københavns Universitet3 State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China Molecular Pathology Section, Department of Biomedical Sciences, Biotech Research and Innovation Centre, University of Copenhagen, 2200 Copenhagen, Denmark Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211.4 unknown5 Brakebusch Group, BRIC, Faculty of Health and Medical Sciences, Københavns Universitet6 Brakebusch Group, BRIC, Faculty of Health and Medical Sciences, Københavns Universitet
Mammalian oocyte maturation is distinguished by highly asymmetric meiotic divisions during which a haploid female gamete is produced and almost all the cytoplasm is maintained in the egg for embryo development. Actin-dependent meiosis I spindle positioning to the cortex induces the formation of a polarized actin cap and oocyte polarity, and it determines asymmetric divisions resulting in two polar bodies. Here we investigate the functions of Cdc42 in oocyte meiotic maturation by oocyte-specific deletion of Cdc42 through Cre-loxP conditional knockout technology. We find that Cdc42 deletion causes female infertility in mice. Cdc42 deletion has little effect on meiotic spindle organization and migration to the cortex but inhibits polar body emission, although homologous chromosome segregation occurs. The failure of cytokinesis is due to the loss of polarized Arp2/3 accumulation and actin cap formation; thus the defective contract ring. In addition, we correlate active Cdc42 dynamics with its function during polar body emission and find a relationship between Cdc42 and polarity, as well as polar body emission, in mouse oocytes.
Molecular Biology of the Cell, 2013, Vol 24, Issue 24, p. 3832-41