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pubmed:abstractText |
A fundamental issue in steroid hormone regulation is the question of how specific transcription is attained in vivo when several receptors can bind the same DNA sequence in vitro. We report an enhancer of the mouse sex-limited protein (Slp) gene that, unlike previously characterized enhancers, is activated by androgens but not by glucocorticoids or progestins. Potent androgen induction requires both a consensus glucocorticoid (hormone) response element and auxiliary elements also present within a 120-base-pair DNA fragment. Cotransfection assays with wild-type and mutant receptors reveal that glucocorticoid receptor can bind, but not transactivate from, the hormone response element within the enhancer. The positive effect of androgen and the null effect of glucocorticoid appear to require the amino-terminal domains of the respective receptors. Thus, exclusive transcriptional response to androgens, and lack of response to glucocorticoids, derives from factor interactions that are determined by the context of the receptor binding site rather than by its distinct sequence.
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