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J Cell Biol August 16, 2004; 166 (4): 465-71.
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Dynein/dynactin regulate metaphase spindle length by targeting depolymerizing activities to spindle poles.

Gaetz J , Kapoor TM .

During cell division metaphase spindles maintain constant length, whereas spindle microtubules continuously flux polewards, requiring addition of tubulin subunits at microtubule plus-ends, polewards translocation of the microtubule lattice, and removal of tubulin subunits from microtubule minus-ends near spindle poles. How these processes are coordinated is unknown. Here, we show that dynein/dynactin, a multi-subunit microtubule minus-end-directed motor complex, and NuMA, a microtubule cross-linker, regulate spindle length. Fluorescent speckle microscopy reveals that dynactin or NuMA inhibition suppresses microtubule disassembly at spindle poles without affecting polewards microtubule sliding. The observed uncoupling of these two components of flux indicates that microtubule depolymerization is not required for the microtubule transport associated with polewards flux. Inhibition of Kif2a, a KinI kinesin known to depolymerize microtubules in vitro, results in increased spindle microtubule length. We find that dynein/dynactin contribute to the targeting of Kif2a to spindle poles, suggesting a model in which dynein/dynactin regulate spindle length and coordinate flux by maintaining microtubule depolymerizing activities at spindle poles.

PubMed ID: 15314063
PMC ID: PMC1401226
Article link: J Cell Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: abl1 arhgef7 dctn2 gpsm2 kif2a kif2c numa1

Article Images: [+] show captions
References [+] :
Cassimeris, Accessory protein regulation of microtubule dynamics throughout the cell cycle. 1999, Pubmed, Xenbase