title: Transcriptional factor C/EBP binds to and transactivates the enhancer element II of the hepatitis B virus.
abstract: The human hepatitis B Virus genome (HBV) contains a liver-specific enhancer upstream of the X ORF which has been studied in detail by several investigators. A second liver-specific enhancer element, designated here as enhancer II, has been relatively recently described in the HBV genome, which is located within the core/pregenomic promoter. We have studied the interactions of transcriptional factors with this element and show here that the nuclear factor CCAAT/enhancer binding protein (C/EBP) binds at a unique site within these sequences. Further, using the transient cotransfection scheme of expression with C/EBP encoding vectors and an enhancer II-reporter gene construct, we demonstrate that the enhancer element II responds to increasing amounts of C/EBP by displaying transactivation. Evidence for the functional role of the enhancer element II in transcriptional regulation of the HBV gene expression is presented. A major influence of the enhancer II appears to be on the surface antigen expression.
authors.affiliation: Department of Microbiology and Immunology, Biochemistry, Biophysics and Genetics, University of Colorado School of Medicine, Denver 80262.
authors.forename: M
authors.initials: M
authors.lastname: López-Cabrera
authors.forename: J
authors.initials: J
authors.lastname: Letovsky
authors.forename: K Q
authors.initials: KQ
authors.lastname: Hu
authors.forename: A
authors.initials: A
authors.lastname: Siddiqui
mesh_terms: D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral; D006515:Hepatitis B virus / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors