title: Divergent microtubule assembly rates after short- versus long-term loss of end-modulating kinesins.
abstract: Depletion of microtubule (MT) regulators can initiate stable alterations in MT assembly rates that affect chromosome instability and mitotic spindle function, but the manner by which cellular MT assembly rates can stably increase or decrease is not understood. To investigate this phenomenon, we measured the response of microtubule assembly to both rapid and long-term loss of MT regulators MCAK/Kif2C and Kif18A. Depletion of MCAK/Kif2C by siRNA stably decreases MT assembly rates in mitotic spindles, whereas depletion of Kif18A stably increases rates of assembly. Surprisingly, this is not phenocopied by rapid rapamycin-dependent relocalization of MCAK/Kif2C and Kif18A to the plasma membrane. Instead, this treatment yields opposite affects on MT assembly. Rapidly increased MT assembly rates are balanced by a decrease in nucleated microtubules, whereas nucleation appears to be maximal and limiting for decreased MT assembly rates and also for long-term treatments. We measured amplified tubulin synthesis during long-term depletion of MT regulators and hypothesize that this is the basis for different phenotypes arising from long-term versus rapid depletion of MT regulators.
authors.affiliation: Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA 98195 worde@uw.edu.
authors.forename: Linda
authors.initials: L
authors.lastname: Wordeman
authors.affiliation: Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA 98195.
authors.forename: Justin
authors.initials: J
authors.lastname: Decarreau
authors.affiliation: Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA 98195.
authors.forename: Juan Jesus
authors.initials: JJ
authors.lastname: Vicente
authors.affiliation: Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA 98195.
authors.forename: Michael
authors.initials: M
authors.lastname: Wagenbach
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D045325:HCT116 Cells / Q000166:cytology / Q000187:drug effects; D006367:HeLa Cells / Q000166:cytology / Q000187:drug effects; D006801:Humans; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D008941:Spindle Apparatus / Q000378:metabolism; D022021:Tacrolimus Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C091489:KIF2C protein, human; C500985:MAPRE1 protein, human; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; C502735:KIF18A protein, human; D016547:Kinesins; D022021:Tacrolimus Binding Proteins; D020123:Sirolimus