title: CDC6 requirement for spindle formation during maturation of mouse oocytes.
abstract: A master regulator of DNA replication, CDC6 also functions in the DNA-replication checkpoint by preventing DNA rereplication. Cyclin-dependent kinases (CDKs) regulate the amount and localization of CDC6 throughout the cell cycle; CDC6 phosphorylation after DNA replication initiation leads to its proteolysis in yeast or translocation to the cytoplasm in mammals. Overexpression of CDC6 during the late S phase prevents entry into the M phase by activating CHEK1 kinase that then inactivates CDK1/cyclin B, which is essential for the G2/M-phase transition. We analyzed the role of CDC6 during resumption of meiosis in mouse oocytes, which are arrested in the first meiotic prophase with low CDK1/cyclin B activity; this is similar to somatic cells at the G2/M-phase border. Overexpression of CDC6 in mouse oocytes does not prevent resumption of meiosis. The RNA interference-mediated knockdown of CDC6, however, reveals a new and unexpected function for CDC6; namely, it is essential for spindle formation in mouse oocytes.
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Anger
authors.forename: Paula
authors.initials: P
authors.lastname: Stein
authors.forename: Richard M
authors.initials: RM
authors.lastname: Schultz
mesh_terms: D000818:Animals; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D008540:Meiosis; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D008941:Spindle Apparatus / Q000502:physiology*
chemical_list: C534699:CCNB1 protein, human; C103706:CDC6 protein, human; C502132:CDC6 protein, mouse; C534700:Ccnb1 protein, mouse; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D009687:Nuclear Proteins; D012333:RNA, Messenger