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Molecular mechanisms controlled by cytokinin ofM phase progression in division cycle at tobacco BY-2 cells

烟草 BY-2 细胞分裂周期中细胞分裂素 ofM 期进展控制的分子机制

基本信息

批准号：
17370016
负责人：
MACHIDA Yasunori
金额：
$ 10.1万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17370016/
关键词：
Plant Cell Cell Cycle M phase MAP Kinese myb Transcript Gene myb転写因子

项目摘要

The aim of the present research is to identify processes in M phase of division cycle of tobacco BY-2 cells that might be regulated by cytokinin. In particular, we have sought for target molecular events of cytokinin during phase focusing on expression of Ntmyb genes that are required for transcription of genes during G2/M phase; activation and inactivation of CDK (cyclin-dependent protein kinase); formation &the NACK/MAPKKK complex that is required for activation of the MAP kinase cascade controlling cytokinesis; the activation of the MAP kinase. We have examined effects of depletion of cytokinin and those of expression of genes for cytokinin oxydase, which can degrade this phytohormone, on the M phase progression of BY-2 cells. Our results showed no obvious difference between patterns of M phase progression of BY2 cells incubated with and without cytokinin, respectively. When the cytokinin oxydase genes were introduced and expressed in transgenic Arabidopsis plants, levels of transcr … More ipts of G2/M-phase-specific genes, however, decreased. We also have compared the pattern of the progression of M phase of synchronized BY-2 cells incubated with hormone-free medium to that incubated with trans-zeatin-containing medium. We did not observe clear difference between two patterns obtained in these experiments. We found similar patterns of CDK activation and inactivation when we incubated BY-2 cells with or without cytokinin. Unexpectedly, we, however, found that the level of NACK1 protein increased by 2-fold in the hormone-free medium. Further investigations must be required for understanding of physiological relevance of the unexpected observations obtained by this research project. Although our results did not dearly show target processes of cytokinin during M phase progression, our researches related to cytokinesis have contributed to understanding of new aspects of regulatory mechanisms of cytokinesis in plant cells: (1) CDK phosphorylated both NACK1 and MAPKKK before metaphase, which resulted in interfering the formation of the NACK/MAPKKK complex and after metaphase, these proteins were dephosphorylated, which induced the interaction of these proteins that activated the MAP kinase cascade, leading to the progression of cytokinesis; (2) MYB factors that positively or negatively controlled G2/M-phase-specific transcription in Arabidopsis plants were identified and unidentified factors that may be also involved in the transcription have been predicted. Less

本研究的目的是鉴定烟草BY-2细胞分裂周期M期可能受细胞分裂素调控的过程。特别地，我们已经寻找了细胞分裂素在G2/M期期间的靶分子事件，其集中于G2/M期期间基因转录所需的Ntmyb基因的表达; CDK（细胞周期蛋白依赖性蛋白激酶）的激活和失活;控制胞质分裂的MAP激酶级联激活所需的NACK/MAPKKK复合物的形成; MAP激酶的激活。我们已经研究了细胞分裂素耗竭和细胞分裂素氧化酶基因表达的影响，细胞分裂素氧化酶可以降解这种植物激素，对BY-2细胞的M期进展。我们的结果表明，细胞分裂素孵育和不孵育的BY2细胞的M期进展模式之间没有明显的差异。当细胞分裂素氧化酶基因被导入并在转基因拟南芥植物中表达时，转录水平降低。 ...更多信息而G2/M期特异性基因的ipts减少。我们还比较了M期的同步化BY-2细胞与无淀粉酶培养基孵育的模式，与含反式玉米素的培养基孵育。我们没有观察到在这些实验中获得的两个图案之间的明显差异。我们发现，当我们孵育BY-2细胞与或不与细胞分裂素的CDK激活和失活类似的模式。然而，出乎意料的是，我们发现NACK 1蛋白的水平在无酵母培养基中增加了2倍。必须进行进一步的调查，以了解本研究项目获得的意外观察结果的生理相关性。虽然我们的结果没有清楚地显示细胞分裂素在M期进程中的靶过程，但我们与细胞分裂相关的研究有助于理解植物细胞中细胞分裂调控机制的新方面：（1）CDK在分裂中期之前磷酸化NACK 1和MAPKKK，这导致干扰NACK/MAPKKK复合物的形成，而在分裂中期之后，这些蛋白质被去磷酸化，（2）在拟南芥中鉴定出了MYB因子，这些MYB因子正或负调控G2/M期特异性转录，并预测了可能参与转录的未知因子。少