The synthesis of cytochrome P-450c is induced remarkably in cultured cells as well as animal tissues in response to added chemicals such as 3-methylcholanthrene and 2,3,7,8-tetrachlorodibenzodioxin. To study this mechanism, we joined the sequence of 5'-flanking and upstream regions of the P-450c gene to the structural for chloramphenicol acetyltransferase. The fusion gene was introduced into Hepa-1 cells for the assay of the expressed acetyltransferase activity. At least three cis-acting regulatory regions that are responsible for the inductive expression were determined in the sequences from nucleotide -3674 to -3067, from -1682 to -1429, and from -1139 to -1029, relative to the transcription start site, by external deletion analysis. Further detailed analysis of the region (nucleotides -1139 to -1029) most influential on the inducibility revealed that a regulatory element consisting of 10 base pairs termed a drug regulatory element (DRE) and its homologues were tandemly arranged in this region. The consensus sequence deduced from DREs is 5'-(C)(G)N(GG)(TA)GCTGGG-3'. The regulatory sequence from nucleotide -1140 to -844 is capable of conferring inducibility on a heterologous promoter in a manner independent of its orientation and distance from the subordinate promoter.
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - 1986 Jan 1|
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