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A distinct modulating domain in glucocorticoid receptor monomers in the repression of activity of the transcription
1Kernforschungszentrum Karlsruhe, Institut für Genetik, Germany.
Abstract:
Steroid receptors activate and repress genes. An important class of genes that they repress is controlled by the transcription factor AP-1. The activity of AP-1 is inhibited by the receptor, a mechanism exploited for the therapy of various forms of pathological hyperproliferation in humans. We show here by point mutations in the DNA binding domain and by the choice of steroid ligands that repression of AP-1 activity and transactivation functions of the glucocorticoid receptor (GR) are separable entities. While DNA binding and activation of glucocorticoid-regulated promoters require GR dimerization, we present data that suggest that repression is a function of GR monomers.
Insights
Glucocorticoid receptor (GR) can repress AP-1 activity, a mechanism used in treating hyperproliferation. This study shows GR repression and activation functions are separable, with repression potentially mediated by GR monomers.
Area of Science:
- Molecular biology
- Cellular signaling
- Genetics
Background:
- Steroid receptors modulate gene expression, influencing cellular processes.
- Glucocorticoid receptor (GR) represses genes regulated by the AP-1 transcription factor.
- This repression mechanism is therapeutically relevant for hyperproliferative disorders.
Purpose of the Study:
- To investigate the molecular mechanisms underlying GR-mediated repression of AP-1 activity.
- To determine if GR's transactivation and repression functions are separable.
- To elucidate the role of GR dimerization in these distinct functions.
Main Methods:
- Site-directed mutagenesis in the DNA-binding domain of GR.
- Utilizing specific steroid ligands to modulate GR activity.
- Assessing the impact of these modifications on AP-1 activity and gene transactivation.
Main Results:
- GR's DNA binding and transactivation functions are separable from its repression of AP-1.
- GR dimerization is necessary for DNA binding and activation of target promoters.
- Evidence suggests that GR monomers mediate the repression of AP-1 activity.
Conclusions:
- The distinct functions of GR, including gene activation and repression, are mediated by different molecular mechanisms.
- Repression of AP-1 by GR may occur independently of receptor dimerization.
- Understanding these separable functions offers new insights into therapeutic strategies targeting GR signaling.