Juvenile hormone and its receptor methoprene-tolerant promote ribosomal biogenesis and vitellogenesis in the Aedes aegypti mosquito [Developmental Biology]

Juvenile hormone (JH) controls many biological activities in insects, including development, metamorphosis and reproduction. In the Aedes aegypti mosquito, a vector of Dengue, Yellow fever, Chikungunya and Zika viruses, the metabolic tissue, the fat body, which is an analogue of the vertebrate liver, produces yolk proteins (YPs) for developing oocytes. JH is important for the fat body to acquire competence for YP production. However, the molecular mechanisms of how JH promotes mosquito reproduction are not completely understood. In this study, we show that stimulation of the JH receptor methoprene-tolerant (Met) activates expression of genes encoding the regulator of ribosome synthesis 1 (RRS1) and six ribosomal proteins (two ribosomal large subunit proteins, two ribosomal small subunit proteins and two mitochondrial ribosomal proteins). Moreover, RNAi-mediated depletion of RRS1 decreased biosynthesis of the ribosomal protein L32 (RpL32). Depletion of Met, RRS1, or RpL32 led to retardation of ovarian growth and reduced mosquito fecundity, which may at least in part have resulted from decreased Vg protein production in the fat body. In summary, our results indicate that JH is critical for inducing the expression of ribosomal protein genes and demonstrate that RRS1 mediates the JH signal to enhance both ribosomal biogenesis and vitellogenesis.

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