Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.
Nucleic Acids Res. 2020 Jan 10;48(1):141-156. doi: 10.1093/nar/gkz1072.
Ccr4-Not is a highly conserved complex involved in cotranscriptional RNA surveillance pathways in yeast. In Drosophila, Ccr4-Not is linked to the translational repression of miRNA targets and the posttranscriptional control of maternal mRNAs during oogenesis and embryonic development. Here, we describe a new role for the Ccr4-Not complex in nuclear RNA metabolism in the Drosophila germline. Ccr4 depletion results in the accumulation of transposable and telomeric repeat transcripts in the fraction of chromatin-associated RNA; however, it does not affect small RNA levels or the heterochromatin state of the target loci. Nuclear targets of Ccr4 mainly comprise active full-length transposable elements (TEs) and telomeric and subtelomeric repeats. Moreover, Ccr4-Not foci localize at telomeres in a Piwi-dependent manner, suggesting a functional relationship between these pathways. Indeed, we detected interactions between the components of the Ccr4-Not complex and piRNA machinery, which indicates that these pathways cooperate in the nucleus to recognize and degrade TE transcripts at transcription sites. These data reveal a new layer of transposon control in the germline, which is critical for the maintenance of genome integrity.
Ccr4-Not 是一个高度保守的复合物,参与酵母中转录共调控的 RNA 监测途径。在果蝇中,Ccr4-Not 与 miRNA 靶标的翻译抑制以及卵子发生和胚胎发育过程中母体 mRNA 的转录后调控有关。在这里,我们描述了 Ccr4-Not 复合物在果蝇生殖系核 RNA 代谢中的一个新作用。Ccr4 的耗竭导致染色质相关 RNA 部分中转座和端粒重复转录本的积累;然而,它不影响小 RNA 水平或靶位点的异染色质状态。Ccr4 的核靶标主要包括活跃的全长转座元件 (TEs) 和端粒和端粒旁重复。此外,Ccr4-Not 焦点以 Piwi 依赖性的方式定位于端粒,表明这些途径之间存在功能关系。事实上,我们检测到 Ccr4-Not 复合物和 piRNA 机制的成分之间的相互作用,这表明这些途径在核内合作,以识别和降解转录位点的 TE 转录本。这些数据揭示了生殖系中转座子控制的一个新层面,这对于维持基因组完整性至关重要。