The requirement of GW182 in miRNA-mediated gene silencing in Drosophila larval development

Abstract

AbstractmicroRNAs (miRNAs) regulate a wide variety of biological processes by silencing their target genes. Argonaute (AGO) proteins load miRNAs to form 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 even in the absence of GW182. Nevertheless, gw182-null flies have defects in the expression of chitin-related genes and the formation of the larval trachea system, preventing them to complete the larval development. Our results highlight the importance of both GW182-dependent and -independent silencing mechanisms in vivo.