Sequences flanking the core-binding site modulate glucocorticoid receptor structure and activity.

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• The glucocorticoid receptor (GR) is a transcription factor that regulates gene expression.
• GR binds to specific DNA sequences known as response elements as a homodimer.
• The precise mechanisms by which GR achieves target gene specificity are not fully understood.

Purpose of the Study:

• To investigate how DNA sequences flanking the core-binding site influence GR activity.
• To determine the structural basis for DNA sequence-mediated modulation of GR function.
• To elucidate the role of DNA-induced structural changes in GR-dependent gene regulation.

Main Methods:

• Analysis of nucleotide sequences flanking GR binding sites.
• Structural studies of DNA-binding domain and dimeric GR complex.
• Functional assays in a defined genomic context to assess GR activity.
• Mutagenesis of the GR dimerization interface.

Main Results:

• Nucleotides flanking the core GR binding site vary with the strength of gene activation.
• These flanking sequences induce changes in the 3D structure of the DNA, the GR DNA-binding domain, and the dimeric GR complex.
• Mutating the dimerization interface reduces DNA-induced changes in both GR activity and structure.
• GR activity modulation is downstream of DNA binding and not solely due to occupancy differences.

Conclusions:

• DNA sequence identity at genomic binding sites modulates GR activity through downstream structural changes.
• DNA-induced structural alterations in GR play a significant role in regulating its activity.
• This mechanism contributes to the specificity of GR in targeting individual genes.