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首页> 外文期刊>Cell biology international. >DNA topoisomerase II-dependent control of the cell cycle progression in root meristems of Allium cepa.
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DNA topoisomerase II-dependent control of the cell cycle progression in root meristems of Allium cepa.

机译：DNA拓扑异构酶II依赖性的葱属根分生组织中细胞周期进程的控制。

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摘要

The catalytic ability of DNA topoisomerases (Topo) to generate short-term DNA breaks allow these enzymes to play crucial functions in managing DNA topology during S-phase replication, transcription, and chromatin-remodelling processes required to achieve commitment for the onset and transition through mitosis. Our experiments on root meristem cells of onion (Allium cepa) were designed to gain insight into the contribution of Topo II to plant-specific progression throughout interphase and mitosis. Irrespective of the position of the cell in interphase, the immunofluorescence of Topo II revealed similar nuclear labelling pattern with well defined signals dispersed in the nucleoplasm and the cortical zone of the nucleolus. Only weak labelling was detected in metaphase and anaphase chromosomes. Experiments with two potent anti-Topo II agents, doxorubicin (DOX, an anthracycline) and a bisdioxopiperazine derivative, ICRF-193, suggest that the inhibition-mediated increase in Topo II immunofluorescence may represent a compensatory mechanism, by which an up-regulated expression of the enzyme tends to counteract the drug-induced loss of indispensable catalytic and relaxation functions. γ-H2AX immunolabelling seems to indicate that both DOX- and ICRF-193-induced alterations in cell cycle progression reflect primarily the activity of the G2/M DNA damage checkpoint. Our findings provide evidence for the plant-specific cell cycle control mechanism induced by Topo II inhibitors under DNA stress conditions.
机译：DNA拓扑异构酶（Topo）产生短期DNA断裂的催化能力使这些酶在管理S阶段复制，转录和染色质重塑过程中发挥重要作用，以实现启动和过渡所需的承诺。有丝分裂。我们在洋葱（葱属）的根分生组织细胞上进行的实验旨在深入了解Topo II在整个相间和有丝分裂期间对植物特异性进程的贡献。不论细胞在相间的位置如何，Topo II的免疫荧光显示相似的核标记模式，具有明确定义的信号分散在核质和核仁的皮质区中。在中期和后期染色体中仅检测到弱标记。用两种有效的抗Topo II药物阿霉素（DOX，蒽环类）和双二氧杂哌嗪衍生物ICRF-193进行的实验表明，Topo II免疫荧光的抑制介导的增加可能代表了一种补偿机制，通过该机制上调表达这种酶的趋向于抵消药物引起的必不可少的催化和松弛功能的丧失。 γ-H2AX免疫标记似乎表明DOX和ICRF-193诱导的细胞周期进程改变主要反映了G2 / M DNA损伤检查点的活性。我们的发现为DNA胁迫条件下Topo II抑制剂诱导的植物特异性细胞周期控制机制提供了证据。

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