Glucocorticoid and estrogen regulation of a rat T-kininogen gene

We have examined the regulation of a rat T-kininogen gene by glucocorticoid and estrogen. Expression of the endogenous gene in a rat hepatoma cell line is increased 5-fold and 2-fold in response to dexamethasone and 17 beta-estradiol-3-benzoate, respectively. Various deletion constructs of the 5' region of an isolated T-kininogen gene were fused to a chloramphenicol acetyltransferase (CAT) gene and introduced into the hepatoma cells by electroporation. Analysis of the CAT activity in cell extracts after treatment with glucocorticoid or estrogen revealed that a fragment from -167 to +52 is sufficient to confer full induction. An additional deletion in this region was unresponsive, while a larger fragment (-612 to -100) linked to a heterologous promoter did result in regulated expression. These results suggested that the sequence responsible for the hormonal response was located at -167 to -100 from the transcription start site. This 67 bp region contains a consensus for the core sequence of the glucocorticoid responsive element (GRE) and the estrogen responsive element (ERE). Interestingly these elements are located within 7 bp of each other and both sequences overlap a 16 bp palindrome that may be important in hormone receptor-DNA recognition.