Glucocorticoid regulation of murine leukemia virus transcription elements is specified by determinants within the viral enhancer region.

The transcriptional control region (the long terminal repeat, LTR) of the leukemogenic murine retrovirus SL3-3 contains a glucocorticoid-responsive consensus sequence, as does the corresponding region of the nonleukemogenic virus Akv. Dexamethasone increases gene expression directed by both LTR sequences. However, the responses of the LTRs of the two viruses to dexamethasone differ according to the cell line in which the response is measured. The results of these studies provide insights regarding differences in response to glucocorticoids dependent upon cell line and indicate that the glucocorticoid-responsive elements may compose one of the determinants of tissue specificity and pathogenicity of the murine retroviruses.