The effect of dexamethasone on the initiation of beta-globin gene transcription in differentiating Friend cells.

Plasmid subclones of the 5' and 3' regions of the beta major-globin gene have been used as probes to assay the level and character of the transcripts of this gene in differentiating Friend erythroleukemia cells treated with dexamethasone. Using an S1 nuclease protection protocol, it is shown that dexamethasone reduces the amount of precursor-specific sequences in differentiating Friend cells within 30 min without significantly affecting the nuclear turnover of these molecules. The sites of initiation and termination of transcription remained the same during the shutdown of transcription by the hormone. In contrast to the situation in Friend cells, dexamethasone failed to inhibit globin gene transcription in three normal erythroid tissues. The manner in which the Friend virus complex might render the globin genes sensitive to glucocorticoids is discussed.