TMBP200, a XMAP215 homologue of tobacco BY-2 cells, has an essential role in plant mitosis
- 210 Downloads
TMBP200 from tobacco BY-2 cells is a member of the highly conserved family of microtubule-associated proteins that includes Xenopus XMAP215, human TOGp, and Arabidopsis MOR1/GEM1. XMAP215 homologues have an essential role in spindle assembly and function in animals and yeast, but their role in plant mitosis is not fully clarified. Here, we show by immunoblot analysis that TMBP200 levels in synchronously cultured BY-2 cells increased when the cells entered mitosis, thus indicating that TMBP200 plays an important role in mitosis in tobacco. To investigate the role of TMBP200 in mitosis, we employed inducible RNA interference to silence TMBP200 expression in BY-2 cells. The resulting depletion of TMBP200 caused severe defects in bipolar spindle formation and resulted in the appearance of multinucleated cells with variable-sized nuclei. This finding indicates that TMBP200 has an essential role in bipolar spindle formation and function.
KeywordsTMBP200 MOR1 XMAP215 family Mitosis Tobacco BY-2 cells Inducible RNAi
We thank Dr. M. Curtis (University of Zürich, Switzerland) for providing pMDC7 and Dr. Y. Niwa (Shizuoka University, Japan) for the 35S-sGFP(S65T) vector. This work was supported by grant-in-aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (no. 15770033 to H.Y.).
Conflicts of interest statement
The authors declare that they have no conflict of interest.
Supplemental Movie 2 Time-lapse observation of the dynamics of microtubule localization during the inhibition of bipolar spindle formation in a living YTUB-TMRNAi-1 cell (an RNAi induced cell) Images were recorded every 1 min. An image showing nuclear envelope breakdown is set at 0 min. The progression of time before or after the breakdown is shown in the upper right corner of the images. (MOV 7177 kb)
- Jiang CJ, Sonobe S (1993) Identification and preliminary characterization of a 65 kDa higher-plant microtubule-associated protein. J Cell Sci 105:891–901Google Scholar
- Kakimoto T, Shibaoka H (1988) Cytoskeletal ultrastructure of phragmoplast–nuclei complexes isolated from cultured tobacco cells. Protoplasma Suppl 2:95–103Google Scholar
- Kumagai F, Yoneda A, Tomida T, Sano T, Nagata T, Hasezawa S (2001) Fate of nascent microtubules organized at the M/G1 interface, as visualized by synchronized tobacco BY-2 cells stably expressing GFP-tubulin: time-sequence observations of the reorganization of cortical microtubules in living plant cells. Plant Cell Physiol 42:723–732PubMedCrossRefGoogle Scholar