Laboratory of Plant Molecular Biology, Rockefeller University, New York, NY, 10065-6399, USA.
Temasek Life Sciences Laboratory, Singapore City, 117604, Singapore.
New Phytol. 2018 Sep;219(4):1480-1491. doi: 10.1111/nph.15231. Epub 2018 Jun 4.
Dispersed H3K27 trimethylation (H3K27me3) of the AGAMOUS (AG) genomic locus is mediated by CURLY LEAF (CLF), a component of the Polycomb Repressive Complex (PRC) 2. Previous reports have shown that the AG second intron, which confers AG tissue-specific expression, harbors sequences targeted by several positive and negative regulators. Using RACE reverse transcription polymerase chain reaction, we found that the AG intron 2 encodes several noncoding RNAs. RNAi experiment showed that incRNA4 is needed for CLF repressive activity. AG-incRNA4RNAi lines showed increased leaf AG mRNA levels associated with a decrease of H3K27me3 levels; these plants displayed AG overexpression phenotypes. Genetic and biochemical analyses demonstrated that the AG-incRNA4 can associate with CLF to repress AG expression in leaf tissues through H3K27me3-mediated repression and to autoregulate its own expression level. The mechanism of AG-incRNA4-mediated repression may be relevant to investigations on tissue-specific expression of Arabidopsis MADS-box genes.
AG 基因座的分散 H3K27 三甲基化（H3K27me3）由卷曲叶（CLF）介导，CLF 是多梳抑制复合物（PRC）2 的一个组成部分。先前的报告表明，赋予 AG 组织特异性表达的 AG 第二内含子含有几个正调控和负调控因子靶向的序列。通过 RACE 逆转录聚合酶链反应，我们发现 AG 内含子 2 编码几种非编码 RNA。RNAi 实验表明，lncRNA4 是 CLF 抑制活性所必需的。AG-incRNA4RNAi 系表现出叶片 AG mRNA 水平升高，与 H3K27me3 水平降低相关；这些植物表现出 AG 过表达表型。遗传和生化分析表明，AG-incRNA4 可以与 CLF 结合，通过 H3K27me3 介导的抑制来抑制叶片组织中 AG 的表达，并自我调节其自身的表达水平。AG-incRNA4 介导的抑制机制可能与拟南芥 MADS 盒基因的组织特异性表达研究有关。
