Mutator transposon activation after UV-B involves chromatin remodeling.
Mutator transposon activation after UV-B involves chromatin remodeling.
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DOI：
10.4161/epi.5.4.11751
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发表时间：
2010-05-16
期刊：
影响因子：
3.7
通讯作者：
Casati P
中科院分区：
文献类型：
--
作者：
Qüesta JI;Walbot V;Casati P
MUDR/Mu转座子的自发沉默发生在活跃植物后代中的~10%-100%，一旦沉默，重新激活的情况非常罕见。到目前为止，只有辐射治疗重新激活了沉默的Mu；例如，UV-B辐射重新激活了突变体活性。在这里，我们研究了UV-B通过监测转录丰度、表观遗传DNA标记和与这些元素相关的染色质因子来重新激活Mu转座子的可能机制。我们证明，经过8h的UV-B处理后，Mudra和B转录产物在活跃的突变体和沉默植物中都有较高水平的表达，并且在MuDR的启动子区域发生的染色质重塑事件不同于非自主的MU1元件。随着转录物丰度的增加，组蛋白H3乙酰化增加，DNA和H3K9me2甲基化减少。未检测到siRNA水平的变化。相比之下，在沉默植物中，UV-B后Mu元件中H3K9me2的减少是显著的，这表明K9中H3甲基化的早期变化、染色质重塑和转录因子结合直接参与了UV-B对玉米转座子的重新激活。
Spontaneous silencing of MuDR/Mu transposons occurs in ~10 – 100% of the progeny of an active plant, and once silenced reactivation is very rare. To date, only radiation treatments have reactivated silenced Mu; for example UV-B radiation reactivated Mutator activities. Here we have investigated possible mechanisms by which UV-B could reactivate Mu transposons by monitoring transcript abundance, epigenetic DNA marks, and chromatin factors associated with these elements. We demonstrate that both mudrA and B transcripts are expressed at higher levels after an 8 h-UV-B treatment, in both active Mutator and silencing plants, and that different chromatin remodeling events occur in the promoter regions of MuDR than in non-autonomous Mu1 elements. Increased transcript abundance is accompanied by an increase in histone H3 acetylation and by decreased DNA and H3K9me2 methylation. No changes in siRNA levels were detected. In contrast, the decrease in H3K9me2 present at Mu elements after UV-B is significant in silencing plants, suggesting that early changes in H3 methylation in K9, chromatin remodeling, and transcription factor binding contribute directly to transposon reactivation by UV-B in maize.