title: KLP-7 acts through the Ndc80 complex to limit pole number in C. elegans oocyte meiotic spindle assembly.
abstract: During oocyte meiotic cell division in many animals, bipolar spindles assemble in the absence of centrosomes, but the mechanisms that restrict pole assembly to a bipolar state are unknown. We show that KLP-7, the single mitotic centromere-associated kinesin (MCAK)/kinesin-13 in Caenorhabditis elegans, is required for bipolar oocyte meiotic spindle assembly. In klp-7(-) mutants, extra microtubules accumulated, extra functional spindle poles assembled, and chromosomes frequently segregated as three distinct masses during meiosis I anaphase. Moreover, reducing KLP-7 function in monopolar klp-18(-) mutants often restored spindle bipolarity and chromosome segregation. MCAKs act at kinetochores to correct improper kinetochore-microtubule (k-MT) attachments, and depletion of the Ndc-80 kinetochore complex, which binds microtubules to mediate kinetochore attachment, restored bipolarity in klp-7(-) mutant oocytes. We propose a model in which KLP-7/MCAK regulates k-MT attachment and spindle tension to promote the coalescence of early spindle pole foci that produces a bipolar structure during the acentrosomal process of oocyte meiotic spindle assembly.
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene, OR 97403 amyc@uoregon.edu.
authors.forename: Amy A
authors.initials: AA
authors.lastname: Connolly
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene, OR 97403.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sugioka
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene, OR 97403.
authors.forename: Chien-Hui
authors.initials: CH
authors.lastname: Chuang
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene, OR 97403.
authors.forename: Joshua B
authors.initials: JB
authors.lastname: Lowry
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene, OR 97403.
authors.forename: Bruce
authors.initials: B
authors.lastname: Bowerman
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005838:Genotype; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008540:Meiosis; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D009154:Mutation; D009865:Oocytes / Q000378:metabolism*; D010641:Phenotype; D015398:Signal Transduction; D064047:Spindle Poles / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D029742:Caenorhabditis elegans Proteins; D008869:Microtubule-Associated Proteins; C492665:NDC-80 protein, C elegans; C502821:klp-7 protein, C elegans; D016547:Kinesins