A noncoding RNA transcribed from the AGAMOUS (AG) second intron binds to CURLY LEAF and represses AG expression in leaves

First author: Hui‐Wen Wu; Affiliations: Rockefeller University (洛克菲勒大学): New York, USA

Corresponding author: Nam‐Hai Chua

Dispersed H3K27 trimethylation (H3K27me3) of the AGAMOUS (AG) genomic locus is mediated by CURLY LEAF (CLF), a component of the Polycomb Repressive Complex (PRC; 多梳状抑制复合物) 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‐incRNA4 RNAi 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‐ox genes.

AG基因区域的H3K27三甲基化是由多梳状抑制复合物PRC2其中一个组分CLF所介导的。先前的报道显示AG基因上第二个内含子赋予了AG的组织特异性表达，其序列能够被一些正向和负向调控子所靶定。作者通过RACE逆转录聚合酶链反应发现AG第二个内含子编码一些非编码RNA。RNAi干扰试验表明incRNA4对于CLF的活性抑制至关重要。AG‐incRNA4 RNAi干扰株系叶片中的AG基因mRNA水平升高，同时H3K27me3水平降低。另外，这些AG‐incRNA4 RNAi干扰株系表现出AG过表达的表型。遗传和生化分析显示AG‐incRNA4通过CLF介导的H3K27me3抑制AG基因在叶片组织中的表达，并自动调控其自身的表达水平。由 AG‐incRNA4介导的抑制机制可能对于拟南芥MADS‐ox基因组织特异性表达的研究有所启示。

通讯：Nam‐Hai Chua (https://www.rockefeller.edu/our-scientists/heads-of-laboratories/929-nam-hai-chua/)

个人简介：1965年，新加坡大学，植物学与生物化学学士；1967年，哈佛大学，植物学硕士；1969年，哈佛大学，植物学博士。

研究方向：植物响应胁迫、光及侵染的分子信号。

doi: https://doi.org/10.1111/nph.15231

Journal: New Physiologist

First Published: 04 June, 2018

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