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首页> 外文期刊>Journal of Experimental Botany >Reduced expression of top1β gene induces programmed cell death and alters ascorbate metabolism in Daucus carota cultured cells
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Reduced expression of top1β gene induces programmed cell death and alters ascorbate metabolism in Daucus carota cultured cells

机译：top1β基因的表达减少诱导胡萝卜动植物培养的程序性细胞死亡并改变抗坏血酸代谢

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摘要

Topoisomerase I (topo I) is a nuclear enzyme which plays a fundamental role in several pathways involving changes in DNA topology. The topo I-mediated reaction is accomplished by the transient covalent binding of the enzyme to DNA (topo I–DNA complex). Stabilization of the topo I–DNA complex, leading to irreversible double-strand breaks, has been reported to occur in animal cells under oxidative stress conditions and during apoptosis. In order to study the existence of a putative link between the topo I-mediated DNA damage and ascorbate (ASC) metabolism, also involved in the responses against oxidative stress and in the apoptotic process in plants, Daucus carota cells showing reduced expression of the top1β gene encoding the topo Iβ isoform were produced, using an antisense RNA strategy. Two independent transgenic lines (AT1-β/22 and β/36), characterized by a slow growth phenotype, resistance to camptothecin, a specific inhibitor of topo I, but sensitivity to etoposide, an inhibitor of topo II, were investigated in this study. In the absence of external stimuli, AT1-β/22 and β/36 cells underwent programmed cell death (PCD) in a precocious phase of the growth curve. ASC metabolism showed remarkable differences in AT1-β/22 and β/36 cells, compared with control, and the observed alterations were similar to those occurring in tobacco Yellow Bright-2 cells induced to enter PCD by exogenous stimuli. However, differently from other studied examples of PCD, overproduction of reactive oxygen species was not detected in AT1-β/22 and β/36 cells. The relevance of these findings in relation to the signalling pathways leading to PCD is discussed.
机译：拓扑异构酶I（拓扑I）是一种核酶，在涉及DNA拓扑变化的几种途径中起着基本作用。拓扑I介导的反应是通过酶与DNA的瞬时共价结合（拓扑I–DNA复合体）来完成的。据报道，在氧化应激条件下和凋亡过程中，动物细胞中发生了topo I-DNA复合物的稳定化，导致不可逆的双链断裂。为了研究在topo I介导的DNA损伤与抗坏血酸（ASC）代谢之间存在假定的联系，并且还参与了抗氧化胁迫的反应以及植物的凋亡过程，Daucus carota细胞表现出top1β的表达降低使用反义RNA策略产生了编码topoIβ同工型的基因。在这项研究中，研究了两个独立的转基因品系（AT1-β/ 22和β/ 36），其特征在于生长表型缓慢，对喜树碱（一种topo I的特异性抑制剂）具有抗性，但对依托泊苷（一种topo II的抑制剂）具有敏感性。 。在没有外部刺激的情况下，AT1-β/ 22和β/ 36细胞在生长曲线的早熟期经历了程序性细胞死亡（PCD）。与对照相比，ASC代谢在AT1-β/ 22和β/ 36细胞中显示出显着差异，并且观察到的变化与外源性刺激诱导进入PCD的烟草Yellow Bright-2细胞发生的变化相似。但是，与PCD的其他研究实例不同，在AT1-β/ 22和β/ 36细胞中未检测到活性氧的过量产生。讨论了这些发现与导致PCD的信号通路的相关性。

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  • 来源
    《Journal of Experimental Botany》 |2006年第8期|1667-1676|共10页
  • 作者

    Vittoria Locato; Alma Balestrazzi; Laura De Gara; † and Daniela Carbonera;

  • 作者单位

    Department of Plant Biology and Pathology University of Bari Via Orabona 4 I-70125 Bari Italy;

    Department of Genetics and Microbiology University of Pavia Via Ferrata 1 I-27100 Pavia Italy;

    Interdisciplinary Center for Biomedical Research (CIR) Università Campus Biomedico Via Longoni 83 I-00155 Roma Italy;

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