A COUP-TF/Svp homolog is highly expressed during vitellogenesis in the mosquito Aedes aegypti
Autor(es): Miura, K; Zhu, J; Dittmer, NT; Chen, L; Raikhel, AS
Resumo: In the mosquito Aedes aegypti, vitellogenesis is activated via an ecclysteroid hormonal cascade initiated by a blood meal. The functional ecdysone receptor is a heterodimer composed of the ecdysone receptor (EcR) and ultraspiracle, the homolog of the retinoid X receptor. The precise tuning of this hormonal response requires participation of both positive and negative transcriptional regulators. In Drosophila, Svp, a homolog of chicken ovalbumin upstream promoter transcription factor (COUP-TF), inhibits ecdysone receptor complex-mediated transactivation in vitro and in vivo. Here we report the cloning and characterization of the Svp homolog in mosquito Aedes aegypti, AaSvp. It possesses a high degree of amino acid sequence similarity to the members of the COUP-TF/Svp subfamily. AaSvp transcripts and protein are present in the fat body at high levels from the state of arrest to about 60 h post blood meal. AaSvp binds strongly to a variety of direct repeats of the sequence AGGTCA, but weakly to inverted repeats such as hsp27EcRE. Transient transfection assays in Drosophila S2 cells showed that AaSvp was able to repress 20-hydroxyecdysone (20E)-dependent transactivation mediated by the mosquito ecclysteroid receptor complex. These data suggest that AaSvp negatively regulates the 20E signaling in the fat body during mosquito vitellogenesis.
Palavras-Chave: Promoter - Transcription factor ; Retinoic acid receptors ; Ligand - Binding domain ; Thyroid ?Hormone ; Nuclear receptors ; Orphan receptors ; Ecdysteroid receptor ; Response elements ; Crystal ? Structure ; Fat - Body
Imprenta: Journal of Molecular Endocrinology, v. 29, n. 2, p. 223-238, 2002
Identificador do objeto digital: 10.1677/jme.0.0290223
Descritores: Aedes aegypti - Cell
Data de publicação: 2002
