Krüppel homolog1 (Kr‐h1) is a juvenile hormone (JH) response transcriptional factor that transduces JH signalling to repress insect metamorphosis in both hemimetabolous and holometabolous insects. While few studies about microRNAs (miRNAs) downregulating Kr‐h1 expression to mediate insect metamorphosis have been demonstrated in hemimetabolous insects, the miRNAs that target the Kr‐h1 of holometabolous insects have not been reported. Here, we identified two miR‐927 binding sites within the 3′UTR region of Kr‐h1 in Drosophila melanogaster, and miR‐927 was found to downregulate the expression of Kr‐h1. The expression profiles of miR‐927 and Kr‐h1 displayed relatively opposite pattern during most of the larval development stages. Overexpression of miR‐927 in the fat body significantly decreased the expression of Kr‐h1 and resulted in reduced oviposition, increased mortality, delayed pupation, and reduced pupal size. Notably, the co‐overexpression of Kr‐h1 rescued the developmental and growth defects associated with miR‐927 overexpression, indicating that Kr‐h1 is a biologically relevant target of miR‐927. Moreover, the expression of miR‐927 was found to be repressed by JH and its receptor Met/gce, forming a positive regulatory loop of JH signalling. Overall, our studies support a conserved role for the JH/miRNA/Kr‐h1 regulatory axis in growth control during insect development.

中文翻译：

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MicroRNA miR-927靶向少年激素主要应答基因Krüppelhomolog1，以控制果蝇的发育生长。

Krüppelhomolog1（Kr-h1）是一种幼年激素（JH）反应转录因子，可转导JH信号来抑制半代谢和半代谢昆虫的昆虫变态。虽然在半代谢昆虫中很少有关于下调Kr-h1表达以介导昆虫变态的microRNA（miRNA）的研究，但尚未报道靶向全代谢昆虫Kr-h1的miRNA。在这里，我们在果蝇的Kr-h1的3'UTR区域内发现了两个miR-927结合位点，并且发现miR-927下调了Kr-h1的表达。miR‐927和Kr‐h1的表达谱在大多数幼虫发育阶段显示相对相反的模式。脂肪体内miR‐927的过度表达会显着降低Kr‐h1的表达，并导致排卵减少，死亡率增加，化脓延迟和，体积减小。值得注意的是，Kr-h1的共表达挽救了与miR-927过表达相关的发育和生长缺陷，这表明Kr-h1是miR-927的生物学相关靶标。此外，发现JR及其受体Met / gce抑制了miR-927的表达，形成了JH信号传导的正调控环。总体而言，我们的研究支持JH / miRNA / Kr-h1的保守作用 昆虫发育过程中生长控制的调控轴。