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Hormone activation induces nucleosome positioning in vivo
S Belikov1, B Gelius, G Almouzni
1Laboratory of Molecular Genetics, Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, SE-17177 Stockholm, Sweden.
The EMBO Journal
|March 4, 2000
Summary
Glucocorticoid hormone induces mouse mammary tumor virus promoter activity. Hormone activation establishes nucleosome positioning and forms a subnucleosomal particle at the glucocorticoid receptor binding site, revealing a stepwise transcriptional activation process.
Area of Science:
- Molecular Biology
- Gene Regulation
- Chromatin Structure
Background:
- The mouse mammary tumor virus (MMTV) promoter is a well-characterized model for studying hormone-induced gene expression.
- Glucocorticoid hormones regulate gene transcription through specific receptor interactions.
Purpose of the Study:
- To investigate the chromatin structural changes associated with hormone-induced MMTV promoter activation.
- To identify key elements and processes involved in glucocorticoid receptor-mediated transcriptional activation.
Main Methods:
- Utilizing Xenopus laevis oocytes for robust and reproducible hormone-dependent promoter activation.
- Detailed analysis of chromatin structure transitions using high-resolution techniques.
Main Results:
- Hormone activation induced specific translational positioning of nucleosomes, absent in the inactive state.
- A subnucleosomal particle containing the glucocorticoid receptor (GR)-binding region was detected in the active promoter.
- A single GR-binding site was sufficient to trigger the structural transition, independent of basal promoter elements or ongoing transcription.
Conclusions:
- Glucocorticoid hormone triggers a stepwise process for MMTV promoter activation.
- Specific nucleosome positioning and the formation of a subnucleosomal particle are critical early events in transcriptional activation.