The promoter of the human gene for insulin-like growth factor binding protein-1. Basal promoter activity in HEP G2 cells depends upon liver factor B1.
Characterization of the human insulin-like growth factor binding protein-1 (IGFBP-1) promoter was initiated to facilitate study of developmental and hormonal factors regulating IGFBP-1 production. The region immediately 5' to the IGFBP-1 mRNA capsite is typical of a eukaryotic promoter, with a TATA sequence beginning 28 base pairs (bp) and a CCAAT promoter element beginning 72 bp upstream from this capsite. A 1.3-kilobase insert containing the IGFBP-1 capsite and 1205 bp of this putative IGFBP-1 promoter region directs expression of the reporter gene chloramphenicol acetyltransferase (CAT) in an orientation-specific manner in transfected HEP G2 cells, and the capsite identified for the CAT mRNA is identical to that identified for native IGFBP-1 mRNA. These observations suggest that the 1.3-kilobase insert contains the IGFBP-1 promoter. This promoter was further characterized by deletion analysis, site-directed mutagenesis, gel mobility shift assays, and DNaseI protection assays. These studies identify the CCAAT box region as the major cis element involved in basal IGFBP-1 promoter activity in HEP G2 cells, demonstrate that increased basal promoter activity is associated with the binding of at least one HEP G2 nuclear factor to the CCAAT box region, and indicate that the DNA binding factor(s) responsible for increased basal promoter activity is related to liver factor B1. These observations suggest that liver B1 is the major trans-acting factor stimulating basal IGFBP-1 promoter activity in HEP G2 cells.
Suwanichkul
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Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77054.
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D001483:Base Sequence; D006528:Carcinoma, Hepatocellular; D002352:Carrier Proteins / Q000235:genetics*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D005796:Genes; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008113:Liver Neoplasms; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D015345:Oligonucleotide Probes; D011401:Promoter Regions, Genetic; D012315:RNA Caps / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D016385:TATA Box; D014157:Transcription Factors / Q000502:physiology*
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C496487:HNF1A protein, human; C496495:HNF1B protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; D018969:Insulin-Like Growth Factor Binding Proteins; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D012315:RNA Caps; D012333:RNA, Messenger; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D007334:Insulin-Like Growth Factor I