Proteolytic activity of the proteasome is required for female insect reproduction

Non-ATPase regulatory subunits (Rpns) are components of the 26S proteasome involved in polyubiquitinated substrate recognition and deubiquitination in eukaryotes. Here, we identified 15 homologues sequences ofRpn and associated genes by searching the genome and transcriptome databases of the brown planthopper,Nilaparvata lugens , a hemipteran rice pest. Temporospatial analysis showed thatNlRpn genes were significantly highly expressed in eggs and ovaries but were less-highly expressed in males. RNA interference-mediated depletion ofNlRpn genes decreased the proteolytic activity of proteasome and impeded the transcription oflipase andvitellogenin genes in the fat bodies and ovaries in adult females, and reduced the triglyceride content in the ovaries. Decrease of the proteolytic activity of the proteasome via knockdown ofNlRpn s also inhibited the transcription ofhalloween genes, includingNlCYP307A2 ,NlCYP306A2 andNlCYP314A1 , in the 20-hydroxyecdysone (20E) biosynthetic pathway in the ovaries, reduced 20E production in adult females, and impaired ovarian development and oocyte maturation, resulting in reduced fecundity. These novel findings indicate that the proteolytic activity of the proteasome is required for female reproductive processes inN. lugens , thus furthering our understanding of the reproductive and developmental strategies in insects.