title: Condensins I and II are essential for construction of bivalent chromosomes in mouse oocytes.
abstract: In many eukaryotes, condensins I and II associate with chromosomes in an ordered fashion during mitosis and play nonoverlapping functions in their assembly and segregation. Here we report for the first time the spatiotemporal dynamics and functions of the two condensin complexes during meiotic divisions in mouse oocytes. At the germinal vesicle stage (prophase I), condensin I is present in the cytoplasm, whereas condensin II is localized within the nucleus. After germinal vesicle breakdown, condensin II starts to associate with chromosomes and becomes concentrated onto chromatid axes of bivalent chromosomes by metaphase I. REC8 "glues" chromosome arms along their lengths. In striking contrast to condensin II, condensin I localizes primarily around centromeric regions at metaphase I and starts to associate stably with chromosome arms only after anaphase I. Antibody injection experiments show that condensin functions are required for many aspects of meiotic chromosome dynamics, including chromosome individualization, resolution, and segregation. We propose that the two condensin complexes play distinctive roles in constructing bivalent chromosomes: condensin II might play a primary role in resolving sister chromatid axes, whereas condensin I might contribute to monopolar attachment of sister kinetochores, possibly by assembling a unique centromeric structure underneath.
authors.affiliation: Chromosome Dynamics Laboratory, RIKEN Advanced Science Institute, Wako 351-0198, Japan.
authors.forename: Jibak
authors.initials: J
authors.lastname: Lee
authors.forename: Sugako
authors.initials: S
authors.lastname: Ogushi
authors.forename: Mitinori
authors.initials: M
authors.lastname: Saitou
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hirano
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D000951:Antigens, Neoplasm / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000037:antagonists & inhibitors / Q000378:metabolism; D020090:Chromosome Segregation / Q000187:drug effects; D033481:Chromosomes, Mammalian / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D018386:Kinetochores / Q000187:drug effects / Q000378:metabolism; D008540:Meiosis; D051379:Mice; D008813:Mice, Inbred ICR; D008856:Microscopy, Fluorescence; D046912:Multiprotein Complexes / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism*; D021381:Protein Transport; D000097722:Cohesins
chemical_list: D000251:Adenosine Triphosphatases; D000906:Antibodies; D000951:Antigens, Neoplasm; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004250:DNA Topoisomerases, Type II; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D000097722:Cohesins; C550185:SMC2 protein, mouse; C108312:condensin complexes