Adenovirus-mediated Transfer of CCAAT/Enhancer-binding Protein-α Identifies a Dominant Antiproliferative Role for This Isoform in Hepatocytes
| Autor: | Huizhi Lin, John H. Lawrence, Shiqi Yang, Laura A. Matelis, David C. Johns, Ming Yin, Anna Mae Diehl |
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| Rok vydání: | 1996 |
| Předmět: |
Gene isoform
DNA Complementary Genetic Vectors Genes myc Gene Expression Simian virus 40 Biology Kidney Transfection Proto-Oncogene Mas Biochemistry Adenoviridae Cell Line Proto-Oncogene Proteins c-myc Mice Multiplicity of infection Complementary DNA Gene expression Animals Humans RNA Messenger Cloning Molecular Promoter Regions Genetic Molecular Biology Gene Cells Cultured Messenger RNA Rous sarcoma virus Ccaat-enhancer-binding proteins Temperature Nuclear Proteins Cell Biology biology.organism_classification Molecular biology Recombinant Proteins Rats DNA-Binding Proteins Kinetics Adipose Tissue Avian Sarcoma Viruses Liver CCAAT-Enhancer-Binding Proteins Cell Division |
| Zdroj: | Journal of Biological Chemistry. 271:7343-7350 |
| ISSN: | 0021-9258 |
| Popis: | CCAAT/enhancer-binding protein (C/EBP) isoforms are thought to be important regulators of the hepatocyte phenotype. However, the specific physiological roles of different isoforms are poorly understood because hepatocytes express multiple C/EBPs, and various isoforms have overlapping functions. To identify the functions of C/EBPalpha in mature hepatocytes, replication-defective adenovirus vectors were used to efficiently and homogeneously overexpress the mouse C/EBPalpha gene in a SV40 virus-conditionally transformed rat hepatocyte line that can be induced to express C/EBPbeta and C/EBPdelta but that has little endogenous C/EBPalpha expression. Hepatocytes were infected with a recombinant adenovirus vector carrying the cDNA for C/EBPalpha driven by Rous sarcoma virus promoter elements (AdCEBPalpha) or a similar vector carrying the Escherichia coli lacZ gene (Adbetagal). Staining for beta-galactosidase demonstrated an infection efficiency of 100% at a multiplicity of infection of 25 plaque-forming units/cell and persistence of foreign gene expression for at least 9 days. Cultures infected with AdCEBPalpha had 50-fold higher levels of C/EBPalpha mRNA and protein than those infected with Ad-beta-gal, but similar expression of C/EBP-beta. Infection with AdCEBPalpha inhibited proliferation in cells expressing little C/EBPbeta, even when proliferation was driven by the SV40 transforming antigen, and also blunted mitogenic induction of the c-myc proto-oncogene in nontransformed cells with high levels of C/EBPbeta. Although overexpression of C/EBPalpha consistently increased C/EBPalpha DNA binding activity, it was not sufficient for albumin expression. Infection with AdCEBPalpha only increased albumin mRNA levels in nontransformed cells that also expressed relatively high levels of C/EBPbeta. Thus, in hepatocytes, C/EBPalpha has a dominant antiproliferative function, but must interact with other factors to regulate hepatocyte-specific gene expression. |
| Databáze: | OpenAIRE |
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