Estradiol repression of tumor necrosis factor-α transcription requires estrogen receptor activation function-2 and is enhanced by coactivators

The tumor necrosis factor-α (TNF-α) promoter was used to explore the molecular mechanisms of estradiol (E(2))-dependent repression of gene transcription. E(2) inhibited basal activity and abolished TNF-α activation of the TNF-α promoter. The E(2)-inhibitory element was mapped to the −125 to −82 region of the TNF-α promoter, known as the TNF-responsive element (TNF-RE). An AP-1-like site in the TNF-RE is essential for repression activity. Estrogen receptor (ER) β is more potent than ERα at repressing the −1044 TNF-α promoter and the TNF-RE upstream of the herpes simplex virus thymidine kinase promoter, but weaker at activating transcription through an estrogen response element. The activation function-2 (AF-2) surface in the ligand-binding domain is required for repression, because anti-estrogens and AF-2 mutations impair repression. The requirement of the AF-2 surface for repression is probably due to its capacity to recruit p160 coactivators or related coregulators, because overexpressing the coactivator glucocorticoid receptor interacting protein-1 enhances repression, whereas a glucocorticoid receptor interacting protein-1 mutant unable to interact with the AF-2 surface is ineffective. Furthermore, receptor interacting protein 140 prevents repression by ERβ, probably by interacting with the AF-2 surface and blocking the binding of endogenous coactivators. These studies demonstrate that E(2)-mediated repression requires the AF-2 surface and the participation of coactivators or other coregulatory proteins.