Estrogen-related receptor alpha 1 functionally binds as a monomer to extended half-site sequences including ones...

Area of Science:

• Molecular Biology
• Endocrinology
• Gene Regulation

Background:

• Human estrogen-related receptor alpha 1 (hERR alpha 1) is an orphan nuclear receptor.
• hERR alpha 1 shares sequence similarity in its DNA-binding domain with estrogen receptor alpha (ER alpha).
• Previous work purified hERR alpha 1 based on its binding to simian virus 40 (SV40) late promoter sites.

Purpose of the Study:

• To determine the primary structure, DNA, and protein binding specificities of hERR alpha 1.
• To develop in vivo and in vitro assays for hERR alpha 1 functional activities.
• To elucidate the role of hERR alpha 1 in gene regulation, particularly concerning estrogen responses.

Main Methods:

• Determination of primary protein structure.
• DNA binding assays to identify high-affinity binding sites (5'-TCAAG-GTCA-3').
• In vivo and in vitro transcription assays to assess functional activities.
• Protein-protein interaction studies with ER alpha and TFIIB.

Main Results:

• hERR alpha 1 binds DNA as a monomer to a specific high-affinity site.
• Binding sites for hERR alpha 1 were found in cellular promoters, including some estrogen-response elements (EREs).
• hERR alpha 1 functions as a sequence-specific repressor of the SV40 late promoter.
• hERR alpha 1 interacts directly with ER alpha and TFIIB.

Conclusions:

• hERR alpha 1 is a sequence-specific DNA-binding protein with repressor activity.
• Its ability to bind EREs and interact with ER alpha suggests a role in modulating estrogen-dependent gene expression.
• hERR alpha 1 may influence gene responses to estrogen through heterodimerization with or competition with ER alpha.