The activity of the mouse renin promoter in cells that do not normally produce renin is dependent upon the presence of a functional enhancer.

The expression of a hybrid gene containing the promoter region of the mouse Ren-1 or Ren-2 genes and the chloramphenicol acetyl transferase (CAT) gene coding region was analysed in five cell lines that do not normally express the renin gene. The renin promoter is inactive in each of these cell lines unless the SV40 enhancer is also present in the construct. In the latter case, transcription initiates at the normal renin start site. This is in contrast to the situation observed in lymphoid cells where the renin promoter is inactive even when coupled to a functional enhancer [(1987) EMBO J. 6, 1685-1690]. Furthermore, 5'-flanking sequences of Ren-2, placed upstream of the thymidine kinase or SV40 early region promoters do not alter the activity of these promoters in three different cell lines. The results suggest that, except for B cells, the renin promoter is not tissue-specific but that its lack of activity in cells that do not express the gene is not the result of repression but may be due to the absence in these cells of one or several trans-acting positive factors.