Piwi-interacting RNAs (piRNAs) and PIWI proteins are essential in germ cells to repress transposons and regulate mRNAs. In Drosophila, piRNAs bound to the PIWI protein Aubergine (Aub) are transferred maternally to the embryo and regulate maternal mRNA stability through two opposite roles. They target mRNAs by incomplete base pairing, leading to their destabilization in the soma and stabilization in the germ plasm. Here, we report a function of Aub in translation. Aub is required for translational activation of nanos mRNA, a key determinant of the germ plasm. Aub physically interacts with the poly(A)-binding protein (PABP) and the translation initiation factor eIF3. Polysome gradient profiling reveals the role of Aub at the initiation step of translation. In the germ plasm, PABP and eIF3d assemble in foci that surround Aub-containing germ granules, and Aub acts with eIF3d to promote nanos translation. These results identify translational activation as a new mode of mRNA regulation by Aub, highlighting the versatility of PIWI proteins in mRNA regulation.

中文翻译：

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PIWI蛋白茄子募集eIF3以激活种质中的翻译。

piwi相互作用RNA（piRNA）和PIWI蛋白在生殖细胞中是抑制转座子和调节mRNA所必需的。在果蝇中，与PIWI蛋白茄子（Aubbergine）（Aub）结合的piRNA在母体中转移到胚胎中，并通过两种相反的作用调节母体mRNA的稳定性。它们通过不完全的碱基配对靶向mRNA，从而导致它们在体细胞中不稳定并在种质中稳定。在这里，我们报告Aub在翻译中的功能。Aub是nanos mRNA（种质的关键决定因素）的翻译激活所必需的。Aub与poly（A）结合蛋白（PABP）和翻译起始因子eIF3物理相互作用。多核糖体梯度分析揭示了Aub在翻译起始步骤的作用。在种质中，PABP和eIF3d在围绕含Aub的种质颗粒的病灶中聚集，Aub与eIF3d一起促进纳米翻译。这些结果确定了翻译激活是Aub进行mRNA调控的新模式，突显了PIWI蛋白在mRNA调控中的多功能性。