Dual Requirement for the EcR/USP Nuclear Receptor and the dGATAb Factor in an Ecdysone Response in Drosophila melanogaster

AUTOR(ES)

Brodu, Véronique

FONTE

American Society for Microbiology

RESUMO

The EcR/USP nuclear receptor controls Drosophila metamorphosis by activating complex cascades of gene transcription in response to pulses of the steroid hormone ecdysone at the end of larval development. Ecdysone release provides a ubiquitous signal for the activation of the receptor, but a number of its target genes are induced in a tissue- and stage-specific manner. Little is known about the molecular mechanisms involved in this developmental modulation of the EcR/USP-mediated pathway. Fbp1 is a good model of primary ecdysone response gene expressed in the fat body for addressing this question. We show here that the dGATAb factor binds to three target sites flanking an EcR/USP binding site in a 70-bp enhancer that controls the tissue and stage specificity of Fbp1 transcription. We demonstrate that one of these sites and proper expression of dGATAb are required for specific activation of the enhancer in the fat body. In addition, we provide further evidence that EcR/USP plays an essential role as a hormonal timer. Our study provides a striking example of the integration of molecular pathways at the level of a tissue-specific hormone response unit.

Documentos Relacionados

• The ecdysone response enhancer of the Fbp1 gene of Drosophila melanogaster is a direct target for the EcR/USP nuclear receptor.
• Direct repeats bind the EcR/USP receptor and mediate ecdysteroid responses in Drosophila melanogaster.
• Activation of a Delayed-Early Gene Encoding MHR3 by the Ecdysone Receptor Heterodimer EcR-B1–USP-1 but Not by EcR-B1–USP-2
• The dual role of ultraspiracle, the Drosophila retinoid X receptor, in the ecdysone response
• Identification and characterization of a Drosophila nuclear receptor with the ability to inhibit the ecdysone response.