title: Cell cycle-dependent localization and possible roles of the small GTPase Ran in mouse oocyte maturation, fertilization and early cleavage.
abstract: The small GTPase Ran controls numerous cellular processes of the mitotic cell cycle. In this experiment, we investigated the localization and possible roles of Ran during mouse oocyte meiotic maturation, fertilization and early cleavage by using confocal laser scanning microscopy, antibody microinjection and microtubule disturbance. The results showed that Ran was localized mainly in the nucleus (except for the nucleolus) in the oocyte, zygote and early embryo. At pro-metaphase of meiosis I, Ran distributed throughout the cell, but predominantly concentrated around the condensed chromosomes. During the completion of meiosis I and meiosis II, it concentrated to the meiotic spindle microtubules except for the midbody region. After sperm penetration, Ran dispersed with the extrusion of the second polar body and gradually concentrated in the male and female pronuclei thereafter. Ran was also observed to exist diffusely in the cytoplasm in prophase; it concentrated at the mitotic spindle, and migrated to the nucleus during early cleavage. Ran's concentration around the spindle disappeared when microtubule assembly was inhibited by colchicine, while it was concentrated around the chromosomes after microtubule stabilization with taxol treatment. Ran did not display any role in cytokinesis during division when pseudo-cleavage of germinal vesicle-intact oocytes was induced. Anti-Ran antibody microinjection decreased the germinal vesicle breakdown and the first polar body extrusion, and distorted spindle organization and chromosome alignment. Our results indicate that Ran has a cell cycle-dependent localization and may have regulatory roles in cell cycle progression and microtubule organization in mouse oocytes, fertilized eggs and early embryos.
authors.affiliation: State Key Laboratory of Reproductive Biology, Institute of Zoology, The Chinese Academy of Sciences, No. 25 Beisihuanxi Road, Beijing 100080, China.
authors.forename: Yun-Kao
authors.initials: YK
authors.lastname: Cao
authors.forename: Zhi-Sheng
authors.initials: ZS
authors.lastname: Zhong
authors.forename: Da-Yuan
authors.initials: DY
authors.lastname: Chen
authors.forename: Gui-Xue
authors.initials: GX
authors.lastname: Zhang
authors.forename: Heide
authors.initials: H
authors.lastname: Schatten
authors.forename: Qing-Yuan
authors.initials: QY
authors.lastname: Sun
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002453:Cell Cycle / Q000502:physiology; D002478:Cells, Cultured; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D003078:Colchicine / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology; D005260:Female; D005306:Fertilization / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D018613:Microscopy, Confocal; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009866:Oogenesis / Q000502:physiology*; D017239:Paclitaxel / Q000494:pharmacology; D008941:Spindle Apparatus / Q000502:physiology; D014404:Tubulin / Q000032:analysis; D020931:ran GTP-Binding Protein / Q000032:analysis* / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D014404:Tubulin; D000431:Ethanol; D020931:ran GTP-Binding Protein; D017239:Paclitaxel; D003078:Colchicine; D015056:1-Methyl-3-isobutylxanthine