The plant TPX2 protein regulates prospindle assembly before nuclear envelope breakdown

Jan W Vos; Laurent Pieuchot; Jean-Luc Evrard; Natacha Janski; Marc Bergdoll; Dryas de Ronde; Laurent H Perez; Teresa Sardon; Isabelle Vernos; Anne-Catherine Schmit

doi:10.1105/tpc.107.056796

The plant TPX2 protein regulates prospindle assembly before nuclear envelope breakdown

Plant Cell. 2008 Oct;20(10):2783-97. doi: 10.1105/tpc.107.056796. Epub 2008 Oct 21.

Authors

Jan W Vos¹, Laurent Pieuchot, Jean-Luc Evrard, Natacha Janski, Marc Bergdoll, Dryas de Ronde, Laurent H Perez, Teresa Sardon, Isabelle Vernos, Anne-Catherine Schmit

Affiliation

¹ Laboratory of Plant Cell Biology, Wageningen University, 6703 BD Wageningen, The Netherlands.

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Sequence
Animals
Antibodies
Arabidopsis / genetics*
Arabidopsis / metabolism
Arabidopsis / ultrastructure
Arabidopsis Proteins / chemistry
Arabidopsis Proteins / metabolism
Arabidopsis Proteins / physiology*
Cell Nucleus / metabolism
Cell Nucleus / ultrastructure
Cell Wall / metabolism*
Fatty Acids, Unsaturated / pharmacology
Microtubule-Associated Proteins / chemistry
Microtubule-Associated Proteins / metabolism
Microtubule-Associated Proteins / physiology*
Microtubules / metabolism
Microtubules / ultrastructure
Models, Molecular
Molecular Sequence Data
Nicotiana / cytology
Nicotiana / drug effects
Nicotiana / genetics
Nuclear Envelope / metabolism*
Protein Sorting Signals
Protein Structure, Tertiary
Protein Transport / drug effects
Sequence Alignment
Sequence Analysis, Protein
Spindle Apparatus / metabolism*
Xenopus
alpha Karyopherins / metabolism

Substances

Antibodies
Arabidopsis Proteins
Fatty Acids, Unsaturated
Microtubule-Associated Proteins
Protein Sorting Signals
TPX2 protein, Arabidopsis
alpha Karyopherins
leptomycin B