Transiently and stably introduced CCAAT/enhancer-binding-protein genes are constitutively expressed in cultured cells.
CCAAT/enhancer-binding protein (C/EBP) is expressed in certain cell types including hepatocytes and adipocytes. In order to understand the mechanisms that control the expression of the mouse C/EBP gene in the liver as well as in adipocytes, we have studied both the endogenous gene and transfected C/EBP gene constructs. The initiation site of transcription was identified and a strong liver-specific DNase-I hypersensitive site located at -3 kb, which does not appear to contribute functionally to the regulation of the gene in a variety of either transiently or stably transfected cells with constructs which include sequences up to 6-kb upstream of the transcription start. C/EBP gene expression during the transition from preadipocytes to adipocytes was shown to be controlled at the level of transcription. However, adipocytes stably transfected with constructs that include -3.3 kb upstream of the C/EBP gene do not express the reporter genes in a differentiation-specific manner. We detected several DNA-binding proteins that interact with the upstream sites of the C/EBP gene. Those include two labile and two heat-stable site-specific DNA-binding proteins that are present in nuclear extracts from several tissues and cultured cell lines.
Xanthopoulos
K G
KG
Karolinska Institute, Center for Biotechnology, Novum, Sweden.
Cannon
P D
PD
Robinson
G S
GS
Mirkovitch
J
J
Darnell
J E
JE
D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D006528:Carcinoma, Hepatocellular; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D008113:Liver Neoplasms; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D003850:Deoxyribonuclease I