piRNA-mediated nuclear accumulation of retrotransposon transcripts in the Drosophila female germline
piRNA-mediated nuclear accumulation of retrotransposon transcripts in the Drosophila female germline
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DOI：
10.1073/pnas.0805943105
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发表时间：
2008-09-30
影响因子：
11.1
通讯作者：
Bucheton, Alain
中科院分区：
文献类型：
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作者：
Chambeyron, Severine;Popkova, Anna;Bucheton, Alain
转座元素的种系沉默对于维持基因组完整性至关重要。最近的结果表明，这种抑制在很大程度上是通过涉及PIWI相互作用RNA（PIRNA）的RNA沉默途径来实现的。但是，压抑机制尚不清楚。为了解决这个问题，我们利用了可能性破坏果蝇I元素逆转逆转录子的抑制。我们在这里表明，位于白染色质中的功能I元件的抑制需要PIRNA途径的蛋白质，并且卵巢I元素PIRNA的量与女性种系中的抑制强度相关。反义的RNA可能用于产生反义PIRNA，由异质性有缺陷的I元素转录，但是这些反义小RNA的有效产生需要在圣体功能I元件的基因组中存在。最后，我们证明了PIRNA诱导的功能I元素的沉默至少在转录后部分是部分。在压制背景下，这些元素仍会转录，但是他们的某些感官转录本与DOC Retrotransposon一起保存在护士细胞核灶中。在没有I元素PIRNA的情况下，无论是在失调的雌性中还是在Pirna沉默途径的突变体中，感应I元素转录本被转移到发生逆转录置位的卵母细胞。我们的结果表明，PIRNA参与了导致RNA核积累的转录后基因沉默机制。
Germline silencing of transposable elements is essential for the maintenance of genome integrity. Recent results indicate that this repression is largely achieved through a RNA silencing pathway that involves Piwi-interacting RNAs (piRNAs). However the repressive mechanisms are not well understood. To address this question, we used the possibility to disrupt the repression of the Drosophila I element retrotransposon by hybrid dysgenesis. We show here that the repression of the functional I elements that are located in euchromatin requires proteins of the piRNA pathway, and that the amount of ovarian I element piRNAs correlates with the strength of the repression in the female germline. Antisense RNAs, which are likely used to produce antisense piRNAs, are transcribed by heterochromatic defective I elements, but efficient production of these antisense small RNAs requires the presence in the genome of euchromatic functional I elements. Finally, we demonstrate that the piRNA-induced silencing of the functional I elements is at least partially posttranscriptional. In a repressive background, these elements are still transcribed, but some of their sense transcripts are kept in nurse cell nuclear foci together with those of the Doc retrotransposon. In the absence of I element piRNAs, either in dysgenic females or in mutants of the piRNA silencing pathway, sense I element transcripts are transported toward the oocyte where retrotransposition occurs. Our results indicate that piRNAs are involved in a posttranscriptional gene-silencing mechanism resulting in RNA nuclear accumulation.