The Plant TPX2 Protein Regulates Prospindle Assembly before Nuclear Envelope Breakdown

J.W. Vos, L. Pieuchot, J.L. Evrard, N. Janski, M. Bergdoll, D. de Ronde

    Research output: Contribution to journalArticleAcademicpeer-review

    78 Citations (Scopus)

    Abstract

    The Targeting Protein for Xklp2 (TPX2) is a central regulator of spindle assembly in vertebrate cells. The absence or excess of TPX2 inhibits spindle formation. We have defined a TPX2 signature motif that is present once in vertebrate sequences but twice in plants. Plant TPX2 is predominantly nuclear during interphase and is actively exported before nuclear envelope breakdown to initiate prospindle assembly. It localizes to the spindle microtubules but not to the interdigitating polar microtubules during anaphase or to the phragmoplast as it is rapidly degraded during telophase. We characterized the Arabidopsis thaliana TPX2-targeting domains and show that the protein is able to rescue microtubule assembly in TPX2-depleted Xenopus laevis egg extracts. Injection of antibodies to TPX2 into living plant cells inhibits the onset of mitosis. These results demonstrate that plant TPX2 already functions before nuclear envelope breakdown. Thus, plants have adapted nuclear¿cytoplasmic shuttling of TPX2 to maintain proper spindle assembly without centrosomes
    Original languageEnglish
    Pages (from-to)2783-2797
    JournalThe Plant Cell
    Volume20
    Issue number10
    DOIs
    Publication statusPublished - 2008

    Keywords

    • xenopus egg extracts
    • aurora-a activation
    • microtubule nucleation
    • mitotic-spindle
    • cell-cycle
    • gamma-tubulin
    • arabidopsis-thaliana
    • importin-alpha
    • ran gtpase
    • expression

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