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Functional analysis of a Drosophila/Chironomous ultraspiracle chimera to examine the role of USP in ecdysteroid-inducible gene expression.

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Jenna L. Callender (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
Advisor
Vincent Henrich

Abstract: The molting hormone, 20-hydroxyecdysone (20E), orchestrates Drosophila development through the actions of the ecdysteroid receptor, which is a heterodimer of two members of the nuclear hormone receptor superfamily, EcR and Ultraspiracle (USP). The EcR/USP heterodimer mediates ecdysteroid response by inducing or repressing the expression of target genes. In this study a chimeric USP whose ligand binding domain (LBD) was replaced by that of a Chironomus LBD was used to test ecdysteroid responsiveness in vitro and in vivo. This was done to determine if the late larval lethality observed in d/cusp mutant flies is a result of the EcR/d/cUSP heterodimer’s inability to mediate 20E response. The chimeric USP had transcriptional capabilities comparable to those of Drosophila USP with all three DmEcR isoforms in vitro, while the ?DBD versions of the chimeric USP and CtUSP constructs did not show the 20E-inducibility with DmEcRB1 that is seen with DmUSP ?DBD (Beatty et al., 2006). RT-PCR was used to test the ability of EcR/d/cUSP to induce the expression of the 20E-regulated genes, E74A, E74B and BRC-Z1 in larval salivary glands. The expression level of these genes in mutant salivary glands was comparable to the levels seen in salivary glands extracted from wild-type animals. These results suggest the chimeric USP phenotype is not the result of impairment of 20E-inducibility, and that USP may have some function outside its classically understood role as the heterodimeric partner of EcR.

Additional Information

Publication
Thesis
Language: English
Date: 2009
Keywords
Chironomus, Drosophila, Ecdysone, Ecdysteroid receptor, Ultraspiracle
Subjects
Insect hormones.
Ecdysteroids.
Mosaicism.
Drosophila.
Chironomus.