Glucocorticoids are known to be critical to CRH transcriptional regulation, via binding to GREs. GREs are hormone inducible enhancer elements 40 that can activate or repress transcription through cooperative action with additional GRE half-sites or other DNA-bound proteins 41, 42. The nucleotide sequence in which we identified variation (-2232 C/G) is a consensus GRE half- site. GREs exert effects in regions distant from the core promoter 43, and half-sites can interact with one another over distances of hundreds of nucleotides 25. It is also known that cooperative binding among receptors bound to GRE half-sites leads to high occupancy at low concentrations and nonlinearity of binding 44. We used GR-containing nuclear extracts, generated from a hypothalamic cell line, to show that -2232 G results in decreased levels of DNA-protein interactions. These results support the notion that the AGAACA (-2232 C) site is functional.
