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Elife February 19, 2013; 2 e00290.
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Mitotic spindle scaling during Xenopus development by kif2a and importin α.

Wilbur JD , Heald R .

Early development of many animals is characterized by rapid cleavages that dramatically decrease cell size, but how the mitotic spindle adapts to changing cell dimensions is not understood. To identify mechanisms that scale the spindle during Xenopus laevis embryogenesis, we established an in vitro system using cytoplasmic extracts prepared from embryos that recapitulates in vivo spindle size differences between stage 3 (4 cells, 37 µm) and stage 8 (∼4000 cells, 18 µm). We identified the kinesin-13 kif2a as a driver of developmental spindle scaling whose microtubule-destabilizing activity is inhibited in stage 3 spindles by the transport receptor importin α, and activated in stage 8 when importin α partitions to a membrane pool. Altering spindle size in developing embryos impaired spindle orientation during metaphase, but chromosome segregation remained robust. Thus, spindle size in Xenopus development is coupled to cell size through a ratiometric mechanism controlling microtubule destabilization.DOI:

PubMed ID: 23425906
PMC ID: PMC3576809
Article link: Elife
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: aurkb cenpe kif2a kif2c kpna1 mbp tbx2 tpx2 tubb2b tubg1

Article Images: [+] show captions
References [+] :
Brown, Xenopus tropicalis egg extracts provide insight into scaling of the mitotic spindle. 2007, Pubmed, Xenbase