UV-B-induced DNA damage mediates expression changes of cell cycle regulatory genes in Arabidopsis root tips
UV-B-induced DNA damage mediates expression changes of cell cycle regulatory genes in Arabidopsis root tips
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UV-B诱导的DNA损伤介导拟南芥根尖细胞周期调控基因的表达变化
DOI：
10.1007/s00425-010-1340-5
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发表时间：
2011-04-01
期刊：
影响因子：
4.3
通讯作者：
Li, Shaoshan
中科院分区：
文献类型：
--
作者：
Jiang, Lei;Wang, Yan;Li, Shaoshan
尽管许多研究表明UV-B辐射抑制植物生长并调节细胞周期进程，但对其分子和细胞机制知之甚少。在此，我们建立了一个同步的根尖细胞系统来研究紫外线辐射下细胞周期标志基因的表达变化和DNA损伤。细胞周期标志基因的表达分析表明，根尖细胞在6 h内完成了g1到s的转变。在体内同步根尖细胞中，高水平的UV-B辐射（0.45 W m(-2)）诱导了细胞周期调控基因的表达变化。参与G1-to-S转换的基因组蛋白H4和E2Fa在UV-B照射2-6 h时下调；而KRP2 （G1-to-S转化的负调控因子）转录本在2 h时被UV-B上调。CYCD3转录本水平的峰值时间；1是g1向s转变的积极因子，被UV-B辐射延迟。有趣的是，中等水平的UV-B辐射（0.25 W m(-2)）没有改变野生型根尖细胞中这些基因的表达。而突变体uvh1细胞周期调控基因受到较大影响，其环丁烷嘧啶二聚体（CPDs）含量较高。抗坏血酸处理没有改变受高水平UV-B影响的细胞周期调控基因的表达模式。我们的研究结果表明，uv - b诱导的DNA损伤导致植物细胞周期从g1到s转变的延迟。UV-B诱导的G1-to-S阻滞可能是一种防止DNA受损细胞分裂的保护机制，并可能解释太阳UV-B辐射增加下植物生长抑制的原因。
Even though a number of studies have shown that UV-B radiation inhibits plant growth and regulates the cell cycle progress, little is known about the molecular and cellular mechanisms. Here, we developed a synchronous root-tip cell system to investigate expression changes of cell cycle marker genes and DNA damage under UV-B radiation. Expression analysis of cell cycle marker genes revealed that G1-to-S transition in root-tip cells was accomplished within 6 h. In the in vivo synchronous root-tip cells, high level of UV-B radiation (0.45 W m(-2)) induced expression changes of the cell cycle regulatory genes. Genes involved in G1-to-S transition, Histone H4 and E2Fa, were down-regulated by UV-B radiation during 2-6 h; whereas transcripts for KRP2, a negative regulator of G1-to-S transition, were up-regulated by UV-B at 2 h. The peak time for transcript level of CYCD3;1, a positive factor in G1-to-S transition, was delayed by UV-B radiation. Interestingly, a medium level of UV-B radiation (0.25 W m(-2)) did not change the expression of these genes in root tip cells from wild type. However, cell cycle regulatory genes were greatly affected in uvh1 mutant, which exhibited higher content of cyclobutane pyrimidine dimers (CPDs). Ascorbic acid treatment did not change the expression pattern of cell cycle regulatory genes that were affected by high-level UV-B. Our results implied that UV-B-induced DNA damage results in the delay of G1-to-S transition of plant cell cycle. UV-B-induced G1-to-S arrest may be a protective mechanism that prevents cells with damaged DNA from dividing and may explain the plant growth inhibition under increased solar UV-B radiation.