Epigenetic control of a transcription factor at the cross section of two antagonistic pathways
Epigenetic control of a transcription factor at the cross section of two antagonistic pathways
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DOI：
10.4161/epi.2.2.4404
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发表时间：
2007-04-01
期刊：
影响因子：
3.7
通讯作者：
Avramova, Zoya
中科院分区：
文献类型：
--
作者：
Alvarez-Venegas, Raul;Al Abdallat, Ayed;Avramova, Zoya
已知拟南芥WRKY70基因的表达受水杨酸（SA）和茉莉酸（JA）信号通路的拮抗调节。该基因编码一个转录因子，在两条途径的交叉点发挥作用。在这里，我们表明，拟南芥同源的三胸，ATX 1，激活WRKY70基因的表达，并参与建立组蛋白H3尾赖氨酸4（H3K4me3）的核小体残基的三甲基化模式。染色质免疫沉淀（ChIP）分析与抗ATX 1特异性抗体表明，WRKY70是ATX 1组蛋白甲基化酶活性的主要目标，而SA响应基因，PR1，和JA响应基因，THI2.1，是次要目标。PR 1和THI2.1核小体携带与其转录状态无关的H3K4me3标记的意外发现表明，防御反应基因PR 1和THI2.1使其核小体保持在“主动”修饰状态，可能是为细胞需要时快速改变转录做准备。基于实验数据，我们提出了一个模型，可以解释一个单一的表观遗传因素的能力，编排大量的基因的表达，特别是在涉及反应的情况下。
The expression of the Arabidopsis gene WRKY70 is known to be antagonistically regulated by the salicylic acid (SA) and jasmonic acid (JA) signaling pathways. The gene encodes a transcription factor functioning at the crossroad of the two pathways. Here we show that the Arabidopsis homolog of Trithorax, ATX1, activates the expression of the WRKY70 gene and is involved in establishing the trimethylation pattern of histone H3 tail lysine 4 (H3K4me3) residues of its nucleosomes. Chromatin immunoprecipitation (ChIP) analyses with antiATX1 specific antibodies demonstrated that WRKY70 is a primary target for the ATX1 histone methylase activity, while the SA-responsive gene, PR1, and the JA-responsive gene, THI2.1, are secondary targets. The unexpected finding that PR1 and THI2.1 nucleosomes carryH3K4me3-marks unrelated to their transcription states suggests that the defense-response genes PR1 and THI2.1 keep their nucleosomes in 'actively' modified state, perhaps, in preparation for quick-changes of transcription when needed by the cell. Based on the experimental data, we propose a model that could explain the ability of a single epigenetic factor to orchestrate expression of a large number of genes, particularly in cases involving response reactions.