microRNAs (miRNA) are small non-coding RNAs that modulate the myriad biological activities by targeting genes, and many studies showed that miRNAs played a pivotal role in insect development. Here, we find that Bm-miRNA (miR-34) controls larval growth and wing morphology by targeting BmE74 and BmCPG4. Overexpression of miR-34 in the whole body caused a smaller body size, partially displays deformed wings and venation defects in adults. Ablation of miR-34 by transgenic CRISPR/Cas9 technology resulted in a severe developmental delay during the larval stage. Moreover, we confirmed that miR-34 directly targeted BmE74 and BmCPG4 by using a dual luciferase reporter assay in HEK293T cells. Remarkably, loss-of-function of BmCPG4 caused wing defects, which was similar to the phenotype of miR-34 overexpression in animals. In addition, our analysis revealed that ecdysone strongly inhibited miR-34 expression in vivo. Taken together, our study identifies miR-34 as a modulator that regulates larval growth and wing morphogenesis by directly modulating ecdysone signalling and cuticle protein in Bombyx mori.

microRNA（miRNA）是小的非编码RNA，通过靶向基因来调节多种生物活性，许多研究表明miRNA在昆虫发育中起着关键作用。在这里，我们发现Bm-miRNA（miR-34）通过靶向BmE74和BmCPG4控制幼虫的生长和机翼形态。miR-34在整个体内的过度表达会导致较小的体形，部分显示成年人的翅膀变形和静脉缺陷。转基因CRISPR / Cas9技术消除miR-34导致幼虫阶段严重的发育延迟。此外，我们通过在HEK293T细胞中使用双重萤光素酶报告基因检测证实了miR-34直接靶向BmE74和BmCPG4。值得注意的是，BmCPG4的功能丧失引起机翼缺陷，类似于动物中miR-34过表达的表型。此外，我们的分析显示，蜕皮激素在体内强烈抑制miR-34表达。综上所述，我们的研究确定miR-34是通过直接调节家蚕蜕皮激素信号传导和表皮蛋白来调节幼虫生长和机翼形态发生的调节剂。