ON THE COVER

Vol. 73 No.4 December 2008

Technical note

     Plant Aurora kinase has dual roles on chromosome alignment and segregation during mitosis

     For accurate distribution of genetic information by two daughter cells, all chromosomes are aligned on the spindle equator and properly segregated during mitosis. Defects in these processes result in aneuploidy, which can lead to dosage imbalance of genes, inheritance instability, and cancer. Plant Aurora kinases are involved in mitosis. Previously, application of an Aurora kinase inhibitor, Hesperadin, to tobacco BY-2 cultured cells induced aberrant chromosome segregation, such as frequent formation of lagging chromosomes and micronuclei. However, the mechanisms of formation of lagging chromosomes and micronuclei in the inhibition have not yet been investigated. Therefore, we used live cell imaging of GFP-α-tubulin and RFP-CenH3 in BY-2 cells after Hesperadin treatment to analyze the function of plant Aurora kinase during mitosis.
     The cover micrographs show time lapse images of BY-2 cells expressing GFP-α-tubulin (green) and RFP-CenH3 (magenta) from prophase to telophase during mitosis. The white chemical structure represents Hesperadin. The top-right yellow images show the prometaphase cells demonstrating the delay of CenH3 alignment on the spindle equator during chromosome alignment, and anaphase/telophase cells showing the lagging CenH3s during chromosome segregation with Hesperadin treatment. The bottom schematic diagram indicates the two distinct pathways for lagging chromosome formation in plantAurora kinase inhibition
     Two types of dynamics for lagging CenH3s were observed during chromosome segregation. In the frst type, only one CenH3 was lagged, indicating that merotelic attachment was generated. In the second type, both CenH3s remained on the spindle equator, suggesting that cohesin dissociation was inhibited. Thus, the data obtained by live cell imaging suggested that the plant Aurora kinase has dual roles; correction of aberrant kinetochore-microtubule attachment and dissociation of cohesin during chromosome alignment and segregation (see Kurihara D., Matsunaga S., Uchiyama S. and Fukui K. 2008: Plant Cell Physiol.49: 1256-1261 ).

     (Daisuke Kurihara, Sachihiro Matsunaga,Susumu Uchiyama, and Kiichi Fukui, Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan)

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ON THE COVER

Vol. 73 No.4 December 2008
Technical note

Plant Aurora kinase has dual roles on chromosome alignment and segregation during mitosis For accurate distribution of genetic information by two daughter cells, all chromosomes are aligned on the spindle equator and properly segregated during mitosis. Defects in these processes result in aneuploidy, which can lead to dosage imbalance of genes, inheritance instability, and cancer. Plant Aurora kinases are involved in mitosis. Previously, application of an Aurora kinase inhibitor, Hesperadin, to tobacco BY-2 cultured cells induced aberrant chromosome segregation, such as frequent formation of lagging chromosomes and micronuclei. However, the mechanisms of formation of lagging chromosomes and micronuclei in the inhibition have not yet been investigated. Therefore, we used live cell imaging of GFP-α-tubulin and RFP-CenH3 in BY-2 cells after Hesperadin treatment to analyze the function of plant Aurora kinase during mitosis. The cover micrographs show time lapse images of BY-2 cells expressing GFP-α-tubulin (green) and RFP-CenH3 (magenta) from prophase to telophase during mitosis. The white chemical structure represents Hesperadin. The top-right yellow images show the prometaphase cells demonstrating the delay of CenH3 alignment on the spindle equator during chromosome alignment, and anaphase/telophase cells showing the lagging CenH3s during chromosome segregation with Hesperadin treatment. The bottom schematic diagram indicates the two distinct pathways for lagging chromosome formation in plantAurora kinase inhibition Two types of dynamics for lagging CenH3s were observed during chromosome segregation. In the frst type, only one CenH3 was lagged, indicating that merotelic attachment was generated. In the second type, both CenH3s remained on the spindle equator, suggesting that cohesin dissociation was inhibited. Thus, the data obtained by live cell imaging suggested that the plant Aurora kinase has dual roles; correction of aberrant kinetochore-microtubule attachment and dissociation of cohesin during chromosome alignment and segregation (see Kurihara D., Matsunaga S., Uchiyama S. and Fukui K. 2008: Plant Cell Physiol.49: 1256-1261 ). (Daisuke Kurihara, Sachihiro Matsunaga,Susumu Uchiyama, and Kiichi Fukui, Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan)
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