Epigenetic Regulation of Repetitive Elements Is Attenuated by Prolonged Heat Stress in Arabidopsis
Epigenetic Regulation of Repetitive Elements Is Attenuated by Prolonged Heat Stress in Arabidopsis
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DOI：
10.1105/tpc.110.078493
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发表时间：
2010-09-01
期刊：
影响因子：
11.6
通讯作者：
Scheid, Ortrun Mittelsten
中科院分区：
文献类型：
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作者：
Pecinka, Ales;Dinh, Huy Q.;Scheid, Ortrun Mittelsten
表观遗传因素决定真核生物对内部和外部刺激的反应。环境条件是否以及如何反馈到表观遗传景观更多的是一个建议而不是证实的问题。植物是解决这个问题的合适生物，因为它们的无根生活方式和表观遗传调节因子的多样化。我们发现拟南芥的几个重复元件在环境温度和短期热暴露下通过转录基因沉默受到表观遗传调控，在长时间热胁迫下被激活。激活可以在不丢失DNA甲基化的情况下发生，只有轻微的组蛋白修饰变化，但伴随着核小体的丢失和异染色质的去浓缩。尽管去浓缩持续存在，核小体装载和转录沉默在热应激后恢复，但在染色质组装功能受损的突变体中延迟。研究结果提供了证据，表明环境条件可以至少暂时凌驾于表观遗传调控之上，这可能为更永久的表观遗传变化打开了一扇窗。
Epigenetic factors determine responses to internal and external stimuli in eukaryotic organisms. Whether and how environmental conditions feed back to the epigenetic landscape is more a matter of suggestion than of substantiation. Plants are suitable organisms with which to address this question due to their sessile lifestyle and diversification of epigenetic regulators. We show that several repetitive elements of Arabidopsis thaliana that are under epigenetic regulation by transcriptional gene silencing at ambient temperatures and upon short term heat exposure become activated by prolonged heat stress. Activation can occur without loss of DNA methylation and with only minor changes to histone modifications but is accompanied by loss of nucleosomes and by heterochromatin decondensation. Whereas decondensation persists, nucleosome loading and transcriptional silencing are restored upon recovery from heat stress but are delayed in mutants with impaired chromatin assembly functions. The results provide evidence that environmental conditions can override epigenetic regulation, at least transiently, which might open a window for more permanent epigenetic changes.