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XB-ART-54435
Elife January 1, 2018; 7
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Autocatalytic microtubule nucleation determines the size and mass of Xenopus laevis egg extract spindles.

Decker F , Oriola D , Dalton B , Brugués J .


Abstract
Regulation of size and growth is a fundamental problem in biology. A prominent example is the formation of the mitotic spindle, where protein concentration gradients around chromosomes are thought to regulate spindle growth by controlling microtubule nucleation. Previous evidence suggests that microtubules nucleate throughout the spindle structure. However, the mechanisms underlying microtubule nucleation and its spatial regulation are still unclear. Here, we developed an assay based on laser ablation to directly probe microtubule nucleation events in Xenopus laevis egg extracts. Combining this method with theory and quantitative microscopy, we show that the size of a spindle is controlled by autocatalytic growth of microtubules, driven by microtubule-stimulated microtubule nucleation. The autocatalytic activity of this nucleation system is spatially regulated by the limiting amounts of active microtubule nucleators, which decrease with distance from the chromosomes. This mechanism provides an upper limit to spindle size even when resources are not limiting.

PubMed ID: 29323637
PMC ID: PMC5814149
Article link: Elife
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: cox7a2l kif2c mapre1
GO keywords: microtubule nucleation [+]


Article Images: [+] show captions
References [+] :
Brugués, Nucleation and transport organize microtubules in metaphase spindles. 2012, Pubmed, Xenbase