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TPX2 levels modulate meiotic spindle size and architecture in Xenopus egg extracts

The spindle segregates chromosomes in dividing eukaryotic cells, and its assembly pathway and morphology vary across organisms and cell types. We investigated mechanisms underlying differences between meiotic spindles formed in egg extracts of two frog species. Small Xenopus tropicalis spindles resi...

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Detalles Bibliográficos
Autores principales: Helmke, Kara J., Heald, Rebecca
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4121975/
https://www.ncbi.nlm.nih.gov/pubmed/25070954
http://dx.doi.org/10.1083/jcb.201401014
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author Helmke, Kara J.
Heald, Rebecca
author_facet Helmke, Kara J.
Heald, Rebecca
author_sort Helmke, Kara J.
collection PubMed
description The spindle segregates chromosomes in dividing eukaryotic cells, and its assembly pathway and morphology vary across organisms and cell types. We investigated mechanisms underlying differences between meiotic spindles formed in egg extracts of two frog species. Small Xenopus tropicalis spindles resisted inhibition of two factors essential for assembly of the larger Xenopus laevis spindles: RanGTP, which functions in chromatin-driven spindle assembly, and the kinesin-5 motor Eg5, which drives antiparallel microtubule (MT) sliding. This suggested a role for the MT-associated protein TPX2 (targeting factor for Xenopus kinesin-like protein 2), which is regulated by Ran and binds Eg5. Indeed, TPX2 was threefold more abundant in X. tropicalis extracts, and elevated TPX2 levels in X. laevis extracts reduced spindle length and sensitivity to Ran and Eg5 inhibition. Higher TPX2 levels recruited Eg5 to the poles, where MT density increased. We propose that TPX2 levels modulate spindle architecture through Eg5, partitioning MTs between a tiled, antiparallel array that promotes spindle expansion and a cross-linked, parallel architecture that concentrates MTs at spindle poles.
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spelling pubmed-41219752015-02-04 TPX2 levels modulate meiotic spindle size and architecture in Xenopus egg extracts Helmke, Kara J. Heald, Rebecca J Cell Biol Research Articles The spindle segregates chromosomes in dividing eukaryotic cells, and its assembly pathway and morphology vary across organisms and cell types. We investigated mechanisms underlying differences between meiotic spindles formed in egg extracts of two frog species. Small Xenopus tropicalis spindles resisted inhibition of two factors essential for assembly of the larger Xenopus laevis spindles: RanGTP, which functions in chromatin-driven spindle assembly, and the kinesin-5 motor Eg5, which drives antiparallel microtubule (MT) sliding. This suggested a role for the MT-associated protein TPX2 (targeting factor for Xenopus kinesin-like protein 2), which is regulated by Ran and binds Eg5. Indeed, TPX2 was threefold more abundant in X. tropicalis extracts, and elevated TPX2 levels in X. laevis extracts reduced spindle length and sensitivity to Ran and Eg5 inhibition. Higher TPX2 levels recruited Eg5 to the poles, where MT density increased. We propose that TPX2 levels modulate spindle architecture through Eg5, partitioning MTs between a tiled, antiparallel array that promotes spindle expansion and a cross-linked, parallel architecture that concentrates MTs at spindle poles. The Rockefeller University Press 2014-08-04 /pmc/articles/PMC4121975/ /pubmed/25070954 http://dx.doi.org/10.1083/jcb.201401014 Text en © 2014 Helmke and Heald This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
spellingShingle Research Articles
Helmke, Kara J.
Heald, Rebecca
TPX2 levels modulate meiotic spindle size and architecture in Xenopus egg extracts
title TPX2 levels modulate meiotic spindle size and architecture in Xenopus egg extracts
title_full TPX2 levels modulate meiotic spindle size and architecture in Xenopus egg extracts
title_fullStr TPX2 levels modulate meiotic spindle size and architecture in Xenopus egg extracts
title_full_unstemmed TPX2 levels modulate meiotic spindle size and architecture in Xenopus egg extracts
title_short TPX2 levels modulate meiotic spindle size and architecture in Xenopus egg extracts
title_sort tpx2 levels modulate meiotic spindle size and architecture in xenopus egg extracts
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4121975/
https://www.ncbi.nlm.nih.gov/pubmed/25070954
http://dx.doi.org/10.1083/jcb.201401014
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