Conserved molecular mechanism for the stage specificity of the mosquito vitellogenic response to ecdysone
Autor(es): Li, C; Kapitskaya, MZ; Zhu, J; Miura, K; Segraves, W; Raikhel, AS
Resumo: In the mosquito Aedes aegypti, the adult female becomes competent for a vitellogenic response to ecdysone after previtellogenic development. Here, we show that beta FTZ-F1, the nuclear receptor implicated as a competence factor for stage-specific responses to ecdysone during Drosophila metamorphosis, serves a similar function during mosquito vitellogenesis. AaFTZ-F1 is expressed highly in the mosquito fat body during pre- and postvitellogenic periods when ecdysteroid titers are low. The mosquito AaFTZ-F1 transcript nearly disappears in mid-vitellogenesis when ecdysteroid titers are high. An expression peak of HR3, a nuclear receptor implicated in the activation of beta FTZ-P1 in Drosophila, precedes each rise in mosquito FTZ-F1 expression. In in vitro fat body culture, AaFTZ-F1 expression is inhibited by 20-hydroxyecdysone (20E) and superactivated by its withdrawal. Following in vitro AaFTZ-F1 superactivation, a secondary 20E challenge results in superinduction of the early AaE75 gene and the late target VCP gene. Electrophoretic mobility-shift assays show that the onset of ecdysone-response competence in the mosquito fat body is correlated with the appearance of the functional AeFTZ-F1 protein at the end of the previtellogenic development. These findings suggest that a conserved molecular mechanism for controlling stage specificity is reiteratively used during metamorphic and reproductive responses to ecdysone. (C) 2000 Academic Press.
Palavras-Chave: 20-Hydroxyecdysone; Ecdysone; Developmental competence; Nuclear receptor; Early gene; FTZ-F1; Vitellogenesis; Mosquito
Imprenta: Developmental Biology, v. 224, n. 1, p. 96-110, 2000
Identificador do objeto digital: 10.1006/dbio.2000.9792
Descritores: Aedes aegypti - DNA
Data de publicação: 2000
