Author: ["Ram Kumar Mishra","Papia Chakraborty","Alexei Arnaoutov","Beatriz M.A. Fontoura","Mary Dasso"]
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Abstract
The γ-tubulin ring complex (γ-TuRC) nucleates microtubules. The nuclear pore subcomplex Nup107-160 is found to interact and cooperate with γ-TuRC to nucleate microtubules at kinetochores, thereby promoting spindle assembly. The metazoan nuclear pore complex (NPC) disassembles during mitosis, and many of its constituents distribute onto spindles and kinetochores, including the Nup107-160 sub-complex1,2. We have found that Nup107-160 interacts with the γ-tubulin ring complex (γ-TuRC), an essential and conserved microtubule nucleator3,4, and recruits γ-TuRC to unattached kinetochores. The unattached kinetochores nucleate microtubules in a manner that is regulated by Ran GTPase5; such microtubules contribute to the formation of kinetochore fibres (k-fibres)6, microtubule bundles connecting kinetochores to spindle poles. Our data indicate that Nup107-160 and γ-TuRC act cooperatively to promote spindle assembly through microtubule nucleation at kinetochores: HeLa cells lacking Nup107-160 or γ-TuRC were profoundly deficient in kinetochore-associated microtubule nucleation. Moreover, co-precipitated Nup107-160– γ-TuRC complexes nucleated microtubule formation in assays using purified tubulin. Although Ran did not regulate microtubule nucleation by γ-TuRC alone, Nup107-160–γ-TuRC complexes required Ran–GTP for microtubule nucleation. Collectively, our observations show that Nup107-160 promotes spindle assembly through Ran–GTP-regulated nucleation of microtubules by γ-TuRC at kinetochores, and reveal a relationship between nucleoporins and the microtubule cytoskeleton.Cite this article
Mishra, R., Chakraborty, P., Arnaoutov, A. et al. The Nup107-160 complex and γ-TuRC regulate microtubule polymerization at kinetochores. Nat Cell Biol 12, 164–169 (2010). https://doi.org/10.1038/ncb2016 