title: Intra-spindle Microtubule Assembly Regulates Clustering of Microtubule-Organizing Centers during Early Mouse Development.
abstract: Errors during cell division in oocytes and early embryos are linked to birth defects in mammals. Bipolar spindle assembly in early mouse embryos is unique in that three or more acentriolar microtubule-organizing centers (MTOCs) are initially formed and are then clustered into two spindle poles. Using a knockout mouse and live imaging of spindles in embryos, we demonstrate that MTOC clustering during the blastocyst stage requires augmin, a critical complex for MT-dependent MT nucleation within the spindle. Functional analyses in cultured cells with artificially increased numbers of centrosomes indicate that the lack of intra-spindle MT nucleation, but not loss of augmin per se or overall reduction of spindle MTs, is the cause of clustering failure. These data suggest that onset of mitosis with three or more MTOCs is turned into a typical bipolar division through augmin-dependent intra-spindle MT assembly.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan. Electronic address: sadanori.watanabe@bio.nagoya-u.ac.jp.
authors.forename: Sadanori
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Genetic Engineering Team, RIKEN Center for Life Science Technologies, Minatojima Minami-machi, Chuou-ku, Kobe 650-0047, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Shioi
authors.affiliation: Genetic Engineering Team, RIKEN Center for Life Science Technologies, Minatojima Minami-machi, Chuou-ku, Kobe 650-0047, Japan; Animal Resource Development Unit, RIKEN Center for Life Science Technologies, Minatojima Minami-machi, Chuou-ku, Kobe 650-0047, Japan.
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Furuta
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan. Electronic address: goshima@bio.nagoya-u.ac.jp.
authors.forename: Gohta
authors.initials: G
authors.lastname: Goshima
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D022101:Microtubule-Organizing Center / Q000378:metabolism* / Q000648:ultrastructure; D008870:Microtubules / Q000378:metabolism*; D008938:Mitosis
chemical_list: D008869:Microtubule-Associated Proteins; C000612995:haus6 protein, mouse
keywords: MTOC clustering; augmin; early mouse development; spindle; γ-tubulin complex