The human prothrombin gene: transcriptional regulation in HepG2 cells.
The human prothrombin gene is expressed predominantly in hepatocytes. Previous work indicated that this tissue specificity is transcriptionally regulated. In order to identify the cis-acting regulatory elements in the 5' flanking region of the human prothrombin gene which may direct the expression of prothrombin in hepatocytes, a series of hybrid plasmids were constructed linking portions of the 5' flanking region of the human prothrombin gene to the bacterial chloramphenicol acetyltransferase gene. Expression of these hybrid plasmids was examined in calcium phosphate-mediated transient transfections of HepG2 cells, a human hepatoblastoma cell line which expresses prothrombin, and HeLa cells, an adenocarcinoma cell line which does not express detectable amounts of prothrombin. Both the prothrombin promoter and an upstream regulatory region containing sequence homologous to the hepatocyte nuclear factor 1 (HNF-1) binding site (nucleotides -919 to -790 relative to the prothrombin transcription initiation site) were required for expression in HepG2 cells. The upstream region also exhibited non-tissue-specific enhancer activity. Gel mobility shift assays confirmed cell-type-specific differences in the protein-DNA interactions between proteins in HepG2 or HeLa nuclear extracts and either the promoter region or the upstream regulatory region of the gene.
Bancroft
J D
JD
Division of Basic Science Research, Children's Hospital Research Foundation, Cincinnati, Ohio 45229.
McDowell
S A
SA
Degen
S J
SJ
D001483:Base Sequence; D001665:Binding Sites; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D006367:HeLa Cells; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011516:Prothrombin / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid / Q000502:physiology*; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C496487:HNF1A protein, human; C496495:HNF1B protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; D009687:Nuclear Proteins; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D011516:Prothrombin; D015500:Chloramphenicol O-Acetyltransferase