Development. 2018 Dec 17;145(24):dev170670.doi: 10.1242/dev.170670.

The microRNAs let-7 and miR-278 regulate insect metamorphosis and oogenesis by targeting the juvenile hormone early-response gene Krüppel-homolog 1

Jiasheng Song  1 Wanwan Li  1 Haihong Zhao  1 Lulu Gao  1 Yuning Fan  1 Shutang Zhou  2 Affiliations

Abstract

Krüppel-homolog 1 (Kr-h1), a zinc-finger transcription factor, inhibits larval metamorphosis and promotes adult reproduction by transducing juvenile hormone (JH). Although the transcriptional regulation of Kr-h1 has been extensively studied, little is known about its regulation at the post-transcriptional level. Using the migratory locust Locusta migratoria as a model system, we report here that the microRNAs let-7 and miR-278 bound to the Kr-h1 coding sequence and downregulated its expression. Application of let-7 and miR-278 mimics (agomiRs) significantly reduced the level of Kr-h1 transcripts, resulting in partially precocious metamorphosis in nymphs as well as markedly decreased yolk protein precursors, arrested ovarian development and blocked oocyte maturation in adults. Moreover, the expression of let-7 and miR-278 was repressed by JH, constituting a regulatory loop of JH signaling. This study thus reveals a previously unknown regulatory mechanism whereby JH suppresses the expression of let-7 and miR-278, which, together with JH induction of Kr-h1 transcription, prevents the precocious metamorphosis of nymphs and stimulates the reproduction of adult females. These results advance our understanding of the coordination of JH and miRNA regulation in insect development.

Keywords: Female reproduction; Juvenile hormone; Kr-h1; Metamorphosis; MicroRNA.

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