title: Kinesin 5-independent poleward flux of kinetochore microtubules in PtK1 cells.
abstract: Forces in the spindle that align and segregate chromosomes produce a steady poleward flux of kinetochore microtubules (MTs [kMTs]) in higher eukaryotes. In several nonmammalian systems, flux is driven by the tetrameric kinesin Eg5 (kinesin 5), which slides antiparallel MTs toward their minus ends. However, we find that the inhibition of kinesin 5 in mammalian cultured cells (PtK1) results in only minor reduction in the rate of kMT flux from approximately 0.7 to approximately 0.5 microm/min, the same rate measured in monopolar spindles that lack antiparallel MTs. These data reveal that the majority of poleward flux of kMTs in these cells is not driven by Eg5. Instead, we favor a polar "pulling-in" mechanism in which a depolymerase localized at kinetochore fiber minus ends makes a major contribution to poleward flux. One candidate, Kif2a (kinesin 13), was detected at minus ends of fluxing kinetochore fibers. Kif2a remains associated with the ends of K fibers upon disruption of the spindle by dynein/dynactin inhibition, and these K fibers flux.
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, 27599, USA.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Cameron
authors.forename: Ge
authors.initials: G
authors.lastname: Yang
authors.forename: Daniela
authors.initials: D
authors.lastname: Cimini
authors.forename: Julie C
authors.initials: JC
authors.lastname: Canman
authors.forename: Olga
authors.initials: O
authors.lastname: Kisurina-Evgenieva
authors.forename: Alexey
authors.initials: A
authors.lastname: Khodjakov
authors.forename: Gaudenz
authors.initials: G
authors.lastname: Danuser
authors.forename: E D
authors.initials: ED
authors.lastname: Salmon
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D016547:Kinesins / Q000037:antagonists & inhibitors / Q000502:physiology*; D018386:Kinetochores / Q000502:physiology*; D008845:Microinjections; D008870:Microtubules / Q000502:physiology*; D008954:Models, Biological; D011743:Pyrimidines / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013871:Thiones / Q000494:pharmacology; D014404:Tubulin / Q000235:genetics
chemical_list: D011743:Pyrimidines; D011993:Recombinant Fusion Proteins; D013871:Thiones; D014404:Tubulin; D049452:Green Fluorescent Proteins; C400223:monastrol; D016547:Kinesins