title: Caenorhabditis elegans oocyte meiotic spindle pole assembly requires microtubule severing and the calponin homology domain protein ASPM-1.
abstract: In many animals, including vertebrates, oocyte meiotic spindles are bipolar but assemble in the absence of centrosomes. Although meiotic spindle positioning in oocytes has been investigated extensively, much less is known about their assembly. In Caenorhabditis elegans, three genes previously shown to contribute to oocyte meiotic spindle assembly are the calponin homology domain protein encoded by aspm-1, the katanin family member mei-1, and the kinesin-12 family member klp-18. We isolated temperature-sensitive alleles of all three and investigated their requirements using live-cell imaging to reveal previously undocumented requirements for aspm-1 and mei-1. Our results indicate that bipolar but abnormal oocyte meiotic spindles assemble in aspm-1(-) embryos, whereas klp-18(-) and mei-1(-) mutants assemble monopolar and apolar spindles, respectively. Furthermore, two MEI-1 functions--ASPM-1 recruitment to the spindle and microtubule severing--both contribute to monopolar spindle assembly in klp-18(-) mutants. We conclude that microtubule severing and ASPM-1 both promote meiotic spindle pole assembly in C. elegans oocytes, whereas the kinesin 12 family member KLP-18 promotes spindle bipolarity.
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene, OR 97403 Institute of Neuroscience, University of Oregon, Eugene, OR 97403 Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB T2N 4N1, Canada.
authors.forename: Amy A
authors.initials: AA
authors.lastname: Connolly
authors.forename: Valerie
authors.initials: V
authors.lastname: Osterberg
authors.forename: Sara
authors.initials: S
authors.lastname: Christensen
authors.forename: Meredith
authors.initials: M
authors.lastname: Price
authors.forename: Chenggang
authors.initials: C
authors.lastname: Lu
authors.forename: Kathy
authors.initials: K
authors.lastname: Chicas-Cruz
authors.forename: Shawn
authors.initials: S
authors.lastname: Lockery
authors.forename: Paul E
authors.initials: PE
authors.lastname: Mains
authors.forename: Bruce
authors.initials: B
authors.lastname: Bowerman
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D016547:Kinesins / Q000235:genetics / Q000378:metabolism; D008540:Meiosis; D008870:Microtubules / Q000378:metabolism; D048054:Mitogen-Activated Protein Kinase 7 / Q000235:genetics; D009154:Mutation; D009865:Oocytes / Q000201:enzymology; D034622:RNA Interference; D034741:RNA, Small Interfering; D008941:Spindle Apparatus / Q000235:genetics* / Q000378:metabolism; D013696:Temperature
chemical_list: C539484:Aspm-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D034741:RNA, Small Interfering; D048054:Mitogen-Activated Protein Kinase 7; D000251:Adenosine Triphosphatases; C000594402:KLP-18 protein, C elegans; C086678:MEI-1 protein, C elegans; D016547:Kinesins