Dual functions of Nicotiana benthamiana Rae1 in interphase and mitosis
Article first published online: 7 APR 2009
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd
The Plant Journal
Volume 59, Issue 2, pages 278–291, July 2009
How to Cite
Lee, J.-Y., Lee, H.-S., Wi, S.-J., Park, K. Y., Schmit, A.-C. and Pai, H.-S. (2009), Dual functions of Nicotiana benthamiana Rae1 in interphase and mitosis. The Plant Journal, 59: 278–291. doi: 10.1111/j.1365-313X.2009.03869.x
- Issue published online: 30 JUN 2009
- Article first published online: 7 APR 2009
- Received 16 January 2009; revised 28 February; accepted 4 March 2009; published online 7 April 2009.
- cell division;
- multipolar spindles;
- nuclear envelope;
- virus-induced gene silencing
Rae1 performs multiple functions in animal systems, acting in interphase as an mRNA export factor and during mitosis as a mitotic checkpoint and spindle assembly regulator. In this study we characterized multiple functions of Rae1 in plants. Virus-induced gene silencing of Nicotiana benthamiana Rae1, NbRae1, which encodes a protein with four WD40 repeats, resulted in growth arrest and abnormal leaf development. NbRae1 was mainly associated with the nuclear envelope during interphase, and NbRae1 deficiency caused accumulation of poly(A) RNA in the nuclei of leaf cells, suggesting defective mRNA export. In the shoot apex, depletion of NbRae1 led to reduced mitotic activities, accompanied by reduced cyclin-dependent kinase (CDK) activity and decreased expression of cyclin B1, CDKB1-1, and histones H3 and H4. The secondary growth of stem vasculature was also inhibited, indicating reduced cambial activities. Differentiated leaf cells of NbRae1-silenced plants exhibited elevated ploidy levels. Immunolabeling in BY-2 cells showed that NbRae1 protein localized to mitotic microtubules and the cell plate-forming zone during mitosis, and recombinant NbRae1 directly bound to microtubules in vitro. Inhibition of NbRae1 expression in BY-2 cells using a β-estradiol-inducible RNAi system resulted in severe defects in spindle organization and chromosome alignment and segregation, which correlated with delays in cell cycle progression. Together, these results suggest that NbRae1 plays a dual role in mRNA export in interphase and in spindle assembly in mitosis.