Abstract
Pbx1 is a homeodomain transcription factor involved in cAMP-dependent transcriptional regulation of the bovine CYP17 gene. In this study, we have investigated the involvement of Pbx1 in the transcriptional regulation of the human CYP17 gene. Although a sequence identical to previously determined Pbx-binding sites is not present in the promoter region of the human CYP17 gene, three putative Pbx-binding sites are identified by sequence similarity analysis. Coexpression of Pbx1 and a catalytic subunit of protein kinase A (PKA) greatly enhances reporter gene transcription via the 5'-flanking region of the human CYP17 gene. Upon gel shift analysis utilizing nuclear extracts from human adrenal H295R cells, one of the three putative Pbx1-binding sites, -250/-241 bp, shows the typical intense doublet observed with other Pbx-binding sites. 5'-Deletion analyses of the reporter construct containing this Pbx-binding site showed approximately sixfold induction by coexpression of Pbx1 and PKA compared to the basal transcription, suggesting that Pbx1 binds the -250/-241 bp sequence and participates in cAMP-dependent regulation of the human CYP17 gene.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adrenal Glands / enzymology
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Animals
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Base Sequence
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Binding Sites
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Cattle
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Cell Line
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Consensus Sequence
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Cyclic AMP / metabolism*
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Cyclic AMP-Dependent Protein Kinases / biosynthesis
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Cyclic AMP-Dependent Protein Kinases / metabolism*
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DNA-Binding Proteins / biosynthesis
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DNA-Binding Proteins / metabolism*
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Genes, Reporter
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Homeodomain Proteins / biosynthesis
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Homeodomain Proteins / metabolism*
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Humans
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Luciferases / biosynthesis
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Oligodeoxyribonucleotides
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Pre-B-Cell Leukemia Transcription Factor 1
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Promoter Regions, Genetic
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Proto-Oncogene Proteins / biosynthesis
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Proto-Oncogene Proteins / metabolism*
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Recombinant Fusion Proteins / biosynthesis
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Sequence Deletion
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Steroid 17-alpha-Hydroxylase / biosynthesis*
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Transcription, Genetic*
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Transcriptional Activation
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Transfection
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Tumor Cells, Cultured
Substances
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DNA-Binding Proteins
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Homeodomain Proteins
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Oligodeoxyribonucleotides
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Pre-B-Cell Leukemia Transcription Factor 1
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Proto-Oncogene Proteins
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Recombinant Fusion Proteins
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PBX1 protein, human
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Cyclic AMP
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Luciferases
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Steroid 17-alpha-Hydroxylase
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Cyclic AMP-Dependent Protein Kinases