The oestrogen receptor regulates NFkappaB and AP-1 activity in a cell-specific manner

Area of Science:

• Molecular Biology
• Endocrinology
• Cell Biology

Background:

• Estrogens mediate gene expression via the estrogen receptor (ER).
• ER interactions with DNA and other nuclear proteins modulate gene expression.
• ERalpha's role in regulating diverse gene response elements requires further investigation.

Purpose of the Study:

• To investigate ERalpha's ability to regulate reporter gene expression.
• To examine ERalpha's activity on estrogen response elements (EREs), NF-kappaB response elements (NREs), and AP-1/TPA response elements (TREs).
• To determine the cell-specific mechanisms of ERalpha-mediated gene regulation.

Main Methods:

• Transient transfection of ERalpha and reporter gene constructs (beta-galactosidase) in HeLa and HEK-293 cells.
• Utilizing EREs, NREs, and TREs to control reporter gene expression.
• Co-expression of ERalpha with cofactors steroid receptor coactivator-1 alpha (SRC-1alpha) and receptor interacting protein-140 (RIP-140).

Main Results:

• ERalpha activated ERE-driven reporter gene expression in an oestradiol (E2)-dependent manner in both cell types.
• ERalpha repressed TNF-mediated NRE activity by 80% in HeLa cells, but not in HEK-293 cells.
• ERalpha/E2 potentiated TPA-mediated TRE activity two-fold in HeLa cells, but not in HEK-293 cells.
• SRC-1alpha and RIP-140 did not influence ERalpha's modulation of NFkappaB or AP-1 activity in either cell type.

Conclusions:

• ERalpha exhibits cell-specific regulation of gene expression.
• The cell-specific effects of ERalpha are not mediated by SRC-1alpha or RIP-140.
• Additional factors likely contribute to ERalpha's differential gene regulatory functions across cell types.