Tissue-specific transcription of the rat tyrosine hydroxylase gene requires synergy between an AP-1 motif and an overlapping E box-containing dyad.
Transcription of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, is regulated in a tissue-specific manner. We have identified sequences from -205 to -182 as the minimal enhancer for TH in pheochromocytoma cells using site-directed mutagenesis. This segment (TGATTCAGAGGCAGGTGCCTGTGA) is composed of an AP-1 motif (TGATTCA) and an overlapping 20 bp dyad whose core resembles an E box site (CANNTG). Interaction between the two elements is necessary both in vivo and in vitro: mutation of either element caused a 65%-95% reduction in transcription, and the combination of the two elements conferred cell-specific activation on a heterologous promoter; separation of the two elements by an additional helical turn not only disrupted a DNA-protein complex unique to the two elements, but also abolished expression in vivo. Therefore, we conclude that the interaction between the AP-1 and the E box dyad motifs is responsible for cell-specific TH expression.
Yoon
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SO
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111.
Chikaraishi
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DM
D000310:Adrenal Gland Neoplasms / Q000235:genetics / Q000473:pathology; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D015870:Gene Expression / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009841:Oligonucleotides; D010673:Pheochromocytoma / Q000235:genetics / Q000473:pathology; D051381:Rats; D014158:Transcription, Genetic / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000473:pathology; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics*
D009841:Oligonucleotides; D004247:DNA; D014446:Tyrosine 3-Monooxygenase