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Glucocorticoid-induced DNA demethylation and gene memory during development
H Thomassin1, M Flavin, M L Espinás
1Institut Jacques Monod du CNRS, Universités Paris 6-7, Tour 43, 2 Place Jussieu, 75251 Paris Cedex 05, France.
The EMBO Journal
|April 11, 2001
Summary
Glucocorticoid hormones induce DNA demethylation in a rat gene enhancer, establishing a stable molecular memory. This process primes the gene for future responses, crucial for development and liver function.
Area of Science:
- Molecular Biology
- Epigenetics
- Gene Regulation
Background:
- Glucocorticoid hormones are critical regulators of gene expression.
- DNA methylation and chromatin remodeling are key epigenetic mechanisms controlling gene accessibility.
- The liver-specific tyrosine aminotransferase (Tat) gene's regulation involves complex transcription factor interactions.
Purpose of the Study:
- To investigate the role of DNA demethylation in glucocorticoid-mediated gene regulation.
- To understand the temporal sequence of epigenetic events and transcription factor recruitment.
- To explore the developmental significance of these regulatory mechanisms in liver cells.
Main Methods:
- Genomic footprinting analysis in hepatoma cells.
- Chromatin remodeling assays.
- Hormone withdrawal experiments.
- In vitro cultures of fetal hepatocytes.
Main Results:
- Glucocorticoid receptor triggers DNA demethylation in the Tat gene enhancer.
- Demethylation follows rapid chromatin remodeling and HNF-3 recruitment.
- Stable demethylation occurs after hormone withdrawal, suggesting a memory function.
- Developmentally, demethylation precedes gene inducibility, preparing the enhancer for later stimuli.
Conclusions:
- DNA demethylation is a stable epigenetic mark induced by glucocorticoids, contributing to gene regulation.
- This demethylation acts as a molecular memory, enhancing subsequent gene responses.
- Epigenetic priming via demethylation plays a vital role in preparing genes for developmental cues and environmental stimuli.