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Ecdysterone regulatory elements function as both transcriptional activators and repressors
L Dobens1, K Rudolph, E M Berger
1Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755.
Molecular and Cellular Biology
|April 1, 1991
Summary
A synthetic ecdysterone regulatory element (EcRE) from Drosophila controls gene expression. It represses basal transcription without hormone and enhances it upon ecdysterone binding, demonstrating a novel regulatory mechanism.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The ecdysterone regulatory element (EcRE) is crucial for insect development and gene regulation.
- Understanding EcRE function is key to deciphering hormonal control of gene expression in Drosophila.
Purpose of the Study:
- To investigate the regulatory role of a synthetic ecdysterone regulatory element (EcRE) in controlling gene expression.
- To characterize the mechanism of ecdysterone-inducible gene expression mediated by EcRE.
Main Methods:
- Construction of hybrid plasmids with the EcRE adjacent to the herpes simplex virus thymidine kinase promoter and chloramphenicol acetyltransferase (CAT) reporter gene.
- Transfection of Drosophila S3 cells and assay for ecdysterone-inducible CAT expression.
- Analysis of EcRE function when inserted at different positions and in combination with multiple EcRE copies.
Main Results:
- A tandem pair of EcREs repressed basal CAT activity in the absence of ecdysterone.
- Ecdysterone addition led to very high levels of CAT activity, indicating hormone-inducible expression.
- Insertion of EcREs downstream of the gene or co-transfection with additional EcREs modulated basal and induced CAT expression levels.
Conclusions:
- The EcRE binds the ecdysterone receptor in the absence of hormone, acting as a repressor of basal transcription.
- Hormone-bound receptor binding to EcRE significantly enhances transcription.
- The position and number of EcREs influence both basal and induced gene expression levels.