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来自奥地利分子生物技术研究所Julius Brennecke实验室发现了在染色质模式和基因表达中转录子和piRNA途径的重要作用,这篇文章刊登在最新一期《CELL》杂志上。

-2012年11月21日《细胞》


中文翻译


【题目】Piwi和Maelstrom导致的转录子转录沉默和其对染色质及基因表达的影响

【译文】真核生物基因通过转录子被转移,这些转录子因为具有不可控的活性而引起基因组的不稳定性。在动物生殖腺中,piRNA途径沉默转录子,但是其中的分子机制还存在疑问。我们发现在果蝇中HMG蛋白Maelstrom对于Piwi调节的沉默很重要。全基因分析发现RNA聚合酶II招募、新生RNA输出和转座子稳定的RNA水平在缺失Piwi或Maelstrom时发生相关的改变。我们的数据表明在转录水平有成百个转录子拷贝受piRNA调节而表现出沉默。我们发现Piwi对于建立异染色质H3K9me3标记转座子和其基因组环境是必须的。相反,Maelstrom缺失影响转座子H3K9me3的模式,这导致被增加的异染色质的扩散,这也表明Maelstrom位于H3K9me3的上游或是H3K9me3的等位基因。我们的研究工作表明在染色质模式和基因表达中转录子和piRNA途径的重要作用。

英文原稿


[Title]Transcriptional Silencing of Transposons by Piwi and Maelstrom and Its Impact onChromatinStateand Gene Expression

[author]Grzegorz Sienski, Derya Dönertas, Julius Brennecke

[Abstract]Eukaryotic genomes are colonized by transposons whose uncontrolled activity causes genomic instability. The piRNA pathway silences transposons in animal gonads, yet how this is achieved molecularly remains controversial. Here, we show that the HMG protein Maelstrom is essential for Piwi-mediated silencing in Drosophila. Genome-wide assays revealed highly correlated changes in RNA polymerase II recruitment, nascent RNA output, and steady-state RNA levels of transposons upon loss of Piwi or Maelstrom. Our data demonstrate piRNA-mediated trans-silencing of hundreds of transposon copies at the transcriptional level. We show that Piwi is required to establish heterochromatic H3K9me3 marks on transposons and their genomic surroundings. In contrast, loss of Maelstrom affects transposon H3K9me3 patterns only mildly yet leads to increased heterochromatin spreading, suggesting that Maelstrom acts downstream of or in parallel to H3K9me3. Our work illustrates the widespread influence of transposons and the piRNA pathway on chromatin patterns and gene expression.

原文地址

http://www.cell.com/abstract/S0092-8674(12)01303-7

 

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