The EF1A2-PABP-E75 axis coordinates metabolic reprogramming and 20E-dependent reproduction in the mosquito Aedes aegypti

Ovarian development and reproductive maturation in Aedes aegypti critically depend on 20-hydroxyecdysone (20E) signaling and energy metabolic homeostasis. Knockdown of EF1A2 (AAEL017096) profoundly affects lipid nutrient metabolism in the fat body and ovarian development, yet whether this effect involves 20E signaling has remained unclear. Here, we show that EF1A2 silencing significantly suppresses transcription of the Halloween genes CYP314A1, CYP315A1, and CYP307A1, reduces endogenous 20E titers, and blocks downstream hormonal signaling. Differential proteomic analysis reveals that EF1A2 broadly participates in metabolic reprogramming, endoplasmic reticulum protein processing, and mRNA regulation. The poly(A)-binding protein PABP (AAEL010318) is identified as a core downstream effector and is specifically highly expressed in ovaries of post-blood-meal mosquitoes. PABP knockdown causes aberrant lipid accumulation in the fat body, disrupts glycolipid metabolism, and ultimately arrests ovarian development and impairs reproductive output, recapitulating EF1A2 knockdown phenotypes. Mechanistically, EF1A2 directly binds full-length PABP via its domain I, positively regulating PABP protein abundance. PABP regulates transcription of the Halloween genes CYP302A1, CYP306A1, and CYP315A1, thereby modulating 20E titer and, in turn, Vg transcription. PABP also associates with the 3' UTR of E75 mRNA, stabilizing the transcript and activating downstream 20E signaling. E75 positively regulates CYP302A1, CYP306A1, and CYP314A1 through a positive feedback mechanism; E75 downregulation impairs ovarian development and reduces egg production. Collectively, the EF1A2-PABP-E75 axis coordinates hormone biosynthesis and metabolic homeostasis to sustain ovarian development and reproductive capacity, offering molecular targets for mosquito vector control.