Krüppel-homolog 1 mediates juvenile hormone action to promote vitellogenesis and oocyte maturation in the migratory locust

• Kr-h1 is expressed in response to juvenile hormone (JH) in adult female locusts.
• Kr-h1 RNAi phenocopies JH deprival and Met RNAi in locust vitellogenesis.
• Kr-h1 RNAi causes substantial reduction of Vg expression and lipid accumulation.
• Kr-h1 depletion leads to blocked oocyte maturation and ovarian growth.
• JH-receptor complex regulates the transcription of Kr-h1 in locusts.

Juvenile hormone (JH) prevents insect larval metamorphosis and stimulates processes for adult reproduction. Krüppel-homolog 1 (Kr-h1), a zinc finger transcription factor, is shown to mediate the anti-metamorphic effect of JH in both holometabolous and hemimetabolous insects. However, the role of Kr-h1 in JH-mediated reproduction has not been determined. Using the migratory locust, Locusta migratoria, we showed here that Kr-h1 was expressed in response to JH in female adults, and Kr-h1 transcription was directly regulated by the JH-receptor complex comprised of Methoprene-tolerant (Met) and steroid receptor co-activator. We demonstrated that Kr-h1 RNAi phenocopied Met RNAi and JH-deprived condition during post-eclosion development and vitellogenesis of female locusts. Knockdown of Kr-h1 resulted in substantial reduction of Vg expression in the fat body and lipid accumulation in the primary oocytes, accompanied by blocked follicular epithelium development, oocyte maturation and ovarian growth. Our data therefore reveal a crucial role of Kr-h1 in insect vitellogenesis and egg production. This study suggests that JH-Met-Kr-h1 signaling pathway is also functional in insect reproduction.

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