Molecular characterization of the promoter region of a neuroendocrine tumor marker, IA-1.
IA-1 is an intronless gene, which encodes a 510 amino acid protein with a zinc-finger DNA-binding motif that is expressed in tumors of neuroendocrine origin. The 5'-upstream region of the IA-1 gene was recently sequenced. In this paper, the regulatory elements and the promoter region of the 5'-upstream region were analyzed by use of a series of deletion mutants (ranging from +26 bp to -2090 bp upstream of the IA-1 gene), which were tested in a pituitary tumor cell line, AtT-20, and Hela cells by transient transfection assays. These experiments showed that a 506 base pair upstream sequence was sufficient for maximal expression of a reporter gene. Multiple known regulatory elements were found within this region including three E boxes and a clustered Sp-1 site. In addition, Southwestern blot analysis, using a radiolabeled promoter sequence (extending from -108 bp to -66 bp) and nuclear extracts from both neuroendocrine and non-neuroendocrine cell lines, revealed four promoter binding proteins designated PBP1, PBP2, PBP3 and PBP4 with molecular weights of 55 kD, 32 kD, 29 kD, and 27/28 kD, respectively. These studies suggest that several different regulatory elements in the 5'-upstream region of the IA-1 gene and at least four different nuclear proteins may be involved in the cell-specific expression of IA-1.
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Oral Infection and Immunity Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892, USA.
Notkins
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D001665:Binding Sites; D014408:Biomarkers, Tumor; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D017353:Gene Deletion; D006801:Humans; D016296:Mutagenesis; D009363:Neoplasm Proteins / Q000235:genetics*; D018358:Neuroendocrine Tumors / Q000737:chemistry*; D009687:Nuclear Proteins / Q000032:analysis / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D016329:Sp1 Transcription Factor; C087342:INSM1 protein, human; D004247:DNA