Institute of Human Genetics (IGH), CNRS, University of Montpellier, Montpellier, France.
Elife. 2024 Jan 10;13:e95337. doi: 10.7554/eLife.95337.
Small RNAs target their complementary chromatin regions for gene silencing through nascent long non-coding RNAs (lncRNAs). In the ciliated protozoan , the interaction between Piwi-associated small RNAs (scnRNAs) and the nascent lncRNA transcripts from the somatic genome has been proposed to induce target-directed small RNA degradation (TDSD), and scnRNAs not targeted for TDSD later target the germline-limited sequences for programmed DNA elimination. In this study, we show that the SUMO E3 ligase Ema2 is required for the accumulation of lncRNAs from the somatic genome and thus for TDSD and completing DNA elimination to make viable sexual progeny. Ema2 interacts with the SUMO E2 conjugating enzyme Ubc9 and enhances SUMOylation of the transcription regulator Spt6. We further show that Ema2 promotes the association of Spt6 and RNA polymerase II with chromatin. These results suggest that Ema2-directed SUMOylation actively promotes lncRNA transcription, which is a prerequisite for communication between the genome and small RNAs.
小 RNA 通过新生的长非编码 RNA（lncRNA）靶向与其互补的染色质区域以实现基因沉默。在纤毛原生动物中，已提出 Piwi 相关小 RNA（scnRNA）与来自体细胞基因组的新生 lncRNA 转录本之间的相互作用可诱导靶向导向的小 RNA 降解（TDSD），而未被 TDSD 靶向的 scnRNA 随后靶向生殖系受限序列以进行程序性 DNA 消除。在这项研究中，我们表明 SUMO E3 连接酶 Ema2 对于从体细胞基因组积累 lncRNA 以及 TDSD 和完成 DNA 消除以产生有活力的有性后代是必需的。Ema2 与 SUMO E2 缀合酶 Ubc9 相互作用，并增强转录调节剂 Spt6 的 SUMO 化。我们进一步表明，Ema2 促进 Spt6 和 RNA 聚合酶 II 与染色质的结合。这些结果表明，Ema2 定向的 SUMO 化积极促进 lncRNA 转录，这是基因组与小 RNA 之间通讯的先决条件。
