title: Overexpressed TPX2 causes ectopic formation of microtubular arrays in the nuclei of acentrosomal plant cells.
abstract: TPX2 performs multiple roles in microtubule organization. Previously, it was shown that plant AtTPX2 binds AtAurora1 kinase and colocalizes with microtubules in a cell cycle-specific manner. To elucidate the function of TPX2 further, this work analysed Arabidopsis cells overexpressing AtTPX2-GFP. Distinct arrays of bundled microtubules, decorated with AtTPX2-GFP, were formed in the vicinity of the nuclear envelope and in the nuclei of overexpressing cells. The microtubular arrays showed reduced sensitivity to anti-microtubular drugs. TPX2-mediated formation of nuclear/perinuclear microtubular arrays was not specific for the transition to mitosis and occurred independently of Aurora kinase. The fibres were not observed in cells with detectable programmed cell death and, in this respect, they differed from TPX2-dependent microtubular assemblies functioning in mammalian apoptosis. Colocalization and co-purification data confirmed the interaction of importin with AtTPX2-GFP. In cells with nuclear foci of overexpressed AtTPX2-GFP, strong nuclear signals for Ran and importin diminished when microtubular arrays were assembled. This observation suggests that TPX2-mediated microtubule formation might be triggered by a Ran cycle. Collectively, the data suggest that in the acentrosomal plant cell, in conjunction with importin, overexpressed AtTPX2 reinforces microtubule formation in the vicinity of chromatin and the nuclear envelope.
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany, AS CR, v.v.i., Šlechtitelů 31, Olomouc 783 71, Czech Republic.
authors.forename: Beáta
authors.initials: B
authors.lastname: Petrovská
authors.forename: Hana
authors.initials: H
authors.lastname: Jerábková
authors.forename: Lucie
authors.initials: L
authors.lastname: Kohoutová
authors.forename: Vera
authors.initials: V
authors.lastname: Cenklová
authors.forename: Žaneta
authors.initials: Ž
authors.lastname: Pochylová
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Gelová
authors.forename: Gabriela
authors.initials: G
authors.lastname: Kocárová
authors.forename: Lenka
authors.initials: L
authors.lastname: Váchová
authors.forename: Michaela
authors.initials: M
authors.lastname: Kurejová
authors.forename: Eva
authors.initials: E
authors.lastname: Tomastíková
authors.forename: Pavla
authors.initials: P
authors.lastname: Binarová
mesh_terms: D017209:Apoptosis; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D064127:Aurora Kinases / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D018385:Centrosome / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D003198:Computer Simulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D021621:Imaging, Three-Dimensional; D028884:Karyopherins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008938:Mitosis; D009685:Nuclear Envelope / Q000378:metabolism; D059828:Plant Cells / Q000378:metabolism*; D021381:Protein Transport; D013347:Subcellular Fractions / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002843:Chromatin; D028884:Karyopherins; D008869:Microtubule-Associated Proteins; C535123:TPX2 protein, Arabidopsis; D014404:Tubulin; D049452:Green Fluorescent Proteins; D064127:Aurora Kinases
keywords: Arabidopsis thaliana; AtTPX2; Aurora kinase; Ran.; fibres; importin; microtubules; nuclei; γ-tubulin