title: Cyclin B degradation leads to NuMA release from dynein/dynactin and from spindle poles.
abstract: The protein NuMA localizes to mitotic spindle poles where it contributes to the organization of microtubules. In this study, we demonstrate that NuMA loses its stable association with the spindle poles after anaphase onset. Using extracts from Xenopus laevis eggs, we show that NuMA is dephosphorylated in anaphase and released from dynein and dynactin. In the presence of a nondegradable form of cyclin B (Delta90), NuMA remains phosphorylated and associated with dynein and dynactin, and remains localized to stable spindle poles that fail to disassemble at the end of mitosis. Inhibition of NuMA or dynein allows completion of mitosis, despite inducing spindle pole abnormalities. We propose that NuMA functions early in mitosis during the formation of spindle poles, but is released from the spindle after anaphase, to allow spindle disassembly and remodelling of the microtubule network.
authors.affiliation: Wellcome Trust Centre for Cell Biology, ICMB, University of Edinburgh, Edinburgh EH9 3JR, UK.
authors.forename: Katja
authors.initials: K
authors.lastname: Gehmlich
authors.forename: Laurence
authors.initials: L
authors.lastname: Haren
authors.forename: Andreas
authors.initials: A
authors.lastname: Merdes
mesh_terms: D000705:Anaphase; D000818:Animals; D003080:Cold Temperature; D019926:Cyclin B / Q000378:metabolism*; D000072159:Dynactin Complex; D004398:Dyneins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D008845:Microinjections; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000378:metabolism*; D008941:Spindle Apparatus / Q000502:physiology* / Q000648:ultrastructure; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D019926:Cyclin B; D000072159:Dynactin Complex; D008869:Microtubule-Associated Proteins; C489079:NUMA1 protein, Xenopus; D009687:Nuclear Proteins; D029867:Xenopus Proteins; D004398:Dyneins