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AHR38, a homolog of NGFI‐B, inhibits formation of the functional ecdysteroid receptor in the mosquito Aedes aegypti
Author(s) -
Zhu Jinsong,
Miura Ken,
Chen Li,
Raikhel Alexander S.
Publication year - 2000
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/19.2.253
Subject(s) - ecdysteroid , biology , ecdysone receptor , 20 hydroxyecdysone , vitellogenesis , orphan receptor , retinoid x receptor , microbiology and biotechnology , nuclear receptor , drosophila melanogaster , ecdysone , medicine , endocrinology , transcription factor , gene , genetics , oocyte , embryo , hormone
In anautogenous mosquitoes, vitellogenesis, the key event in egg maturation, requires a blood meal. Consequently, mosquitoes are vectors of numerous devastating human diseases. After ingestion of blood, 20‐hydroxyecdysone activates yolk protein precursor ( YPP ) genes in the metabolic tissue, the fat body. An important adaptation for anautogenicity is the previtellogenic developmental arrest (the state‐of‐arrest) preventing the activation of YPP genes in previtellogenic females prior to blood feeding. Here, we show that a retinoid X receptor homolog, Ultraspiracle (AaUSP), which is an obligatory partner in the functional ecdysteroid receptor, exists at the state‐of‐arrest as a heterodimer with the orphan nuclear receptor AHR38, a homolog of Drosophila DHR38 and nerve growth factor‐induced protein B. Yeast two‐hybrid and glutathione S ‐transferase pull‐down assays demonstrate that AHR38 can interact strongly with AaUSP. AHR38 also disrupts binding of ecdysteroid receptor to ecdysone response elements. Cell co‐transfection of AHR38 with AaEcR and AaUSP inhibits ecdysone‐dependent activation of a reporter gene by the ecdysteroid receptor. Co‐immunoprecipitation experiments indicate that AaUSP protein associates with AHR38 instead of AaEcR in fat body nuclei at the state‐of‐arrest.