Sequence-selective interactions of transcription factor elements with tandem glucocorticoid-responsive elements at...

Area of Science:

• Molecular Endocrinology
• Gene Regulation
• Transcription Factors

Background:

• Synergism in transcription enhances gene response when multiple DNA elements bind trans-acting factors.
• Steroid receptors play a key role in steroid-regulated gene transcription through synergistic interactions.
• A previously identified glucocorticoid modulatory element (GME) modulates transcriptional activity of steroid receptor complexes.

Purpose of the Study:

• To investigate the synergistic activity of the GME with a glucocorticoid-responsive element (GRE).
• To characterize the distinct properties of GME-mediated synergism compared to conventional synergism.
• To explore the potential of GME for selective transcriptional modulation.

Main Methods:

• Comparative analysis of GME and GRE activity under varying glucocorticoid concentrations (saturating vs. subsaturating).
• Assessment of GME's effect on partial antiglucocorticoids.
• Evaluation of GME's synergistic potential with tandem GREs and varying element spacing.

Main Results:

• GME displayed synergistic activity with GREs, particularly at subsaturating/physiological glucocorticoid concentrations.
• GME enhanced agonist activity of partial antiglucocorticoids, a novel observation for antisteroid synergism.
• GME exhibited sequence-selective activity, greater efficacy than other tested elements, and insensitivity to spacing.

Conclusions:

• The GME provides a unique mechanism for selective transcriptional modulation by physiological steroid concentrations and antisteroids.
• This modulation affects genes controlled by multiple GREs.
• GME's distinct properties expand the understanding of transcriptional synergism and steroid hormone action.