The Piwi-interacting RNA (piRNA) pathway is a small RNA-based immune system that silences mobile genetic elements in animal germlines. piRNA biogenesis requires a specialized machinery that converts long single-stranded precursors into small RNAs of ∼25-nucleotides in length. This process involves factors that operate in two different subcellular compartments: the nuage/Yb body and mitochondria. How these two sites communicate to achieve accurate substrate selection and efficient processing remains unclear. Here, we investigate a previously uncharacterized piRNA biogenesis factor, Daedalus (Daed), that is located on the outer mitochondrial membrane. Daed is essential for Zucchini-mediated piRNA production and the correct localization of the indispensable piRNA biogenesis factor Armitage (Armi). We found that Gasz and Daed interact with each other and likely provide a mitochondrial "anchoring platform" to ensure that Armi is held in place, proximal to Zucchini, during piRNA processing. Our data suggest that Armi initially identifies piRNA precursors in nuage/Yb bodies in a manner that depends on Piwi and then moves to mitochondria to present precursors to the mitochondrial biogenesis machinery. These results represent a significant step in understanding a critical aspect of transposon silencing; namely, how RNAs are chosen to instruct the piRNA machinery in the nature of its silencing targets.

中文翻译：

---

Daedalus 和 Gasz 将 Armitage 招募到线粒体中，将 piRNA 前体带入生物发生机制。


Piwi 相互作用 RNA (piRNA) 途径是一种基于小 RNA 的免疫系统，可沉默动物种系中的移动遗传元件。 piRNA 生物发生需要一种特殊的机制，将长单链前体转化为长度约 25 个核苷酸的小 RNA。该过程涉及在两个不同的亚细胞区室中起作用的因子：nuage/Yb 体和线粒体。这两个站点如何进行通信以实现准确的底物选择和高效的处理仍不清楚。在这里，我们研究了一种先前未表征的 piRNA 生物发生因子 Daedalus (Daed)，它位于线粒体外膜上。 Daed 对于西葫芦介导的 piRNA 产生以及不可或缺的 piRNA 生物发生因子 Armitage (Armi) 的正确定位至关重要。我们发现 Gasz 和 Daed 相互作用，并可能提供线粒体“锚定平台”，以确保 Armi 在 piRNA 处理过程中固定在靠近 Zucchini 的位置。我们的数据表明，Armi 最初以依赖于 Piwi 的方式识别 nuage/Yb 体中的 piRNA 前体，然后转移到线粒体，将前体呈现给线粒体生物发生机制。这些结果代表了理解转座子沉默的关键方面的重要一步；也就是说，如何选择 RNA 来指导 piRNA 机制了解其沉默靶标的性质。