MicroRNAs (miRNAs) regulate a wide variety of biological processes by silencing their target genes. Argonaute (AGO) proteins load miRNAs to form an RNA-induced silencing complex (RISC), which mediates translational repression and/or mRNA decay of the targets. A scaffold protein called GW182 directly binds AGO and the CCR4-NOT deadenylase complex, initiating the mRNA decay reaction. Although previous studies have demonstrated the critical role of GW182 in cultured cells as well as in cell-free systems, its biological significance in living organisms remains poorly explored, especially in Drosophila melanogaster. Here, we generated gw182-null flies using the CRISPR/Cas9 system and found that, unexpectedly, they can survive until an early second-instar larval stage. Moreover, in vivo miRNA reporters can be effectively repressed in gw182-null first-instar larvae. Nevertheless, gw182-null flies have defects in the expression of chitin-related genes and the formation of the larval trachea system, preventing them from completing larval development. Our results highlight the importance of both GW182-dependent and -independent silencing mechanisms in vivo.

中文翻译：

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果蝇幼虫发育中 miRNA 介导的基因沉默涉及 GW182 依赖性和独立机制。


MicroRNA （miRNA） 通过沉默其靶基因来调节多种生物过程。Argonaute （AGO） 蛋白加载 miRNA 以形成 RNA 诱导的沉默复合物 （RISC），该复合物介导靶标的翻译抑制和/或 mRNA 衰变。一种称为 GW182 的支架蛋白直接结合 AGO 和 CCR4-NOT 脱腺苷酶复合物，引发 mRNA 衰变反应。尽管先前的研究表明 GW182 在培养细胞和无细胞系统中的关键作用，但其在生物体中的生物学意义仍未得到充分探索，尤其是在黑腹果蝇中。在这里，我们使用 CRISPR/Cas9 系统生成了 gw182-null 果蝇，并发现出乎意料的是，它们可以存活到二龄幼虫早期。此外，体内 miRNA 报告基因可在 gw182 缺失的一龄幼虫中被有效抑制。然而，gw182-null 果蝇在几丁质相关基因的表达和幼虫气管系统的形成方面存在缺陷，阻止它们完成幼虫发育。我们的结果强调了 GW182 依赖性和 -非依赖性沉默机制在体内的重要性。