Characterization of a specific region in the hepatitis B virus enhancer I for the efficient expression of X gene in the hepatic cell

Virology. 1997 Sep 29;236(2):279-87. doi: 10.1006/viro.1997.8750.


Hepatitis B virus (HBV) enhancer I has been shown to consist of several cis-acting sequences for the HBV gene expression efficiently in certain types of cells. Transcriptional regulation of HBV X gene mediated by enhancer I might be one of the mechanisms by which HBV obtains hepatotropism. By mutagenesis analysis of enhancer I function in the enhancer I/X gene promoter complex, we characterized a specific transcriptional regulatory region (designated as a LSR element, nt 989-1030) of enhancer I for the X gene promoter by means of the transient transfection technique using hepatic and nonhepatic cells. Based on the analysis of protein factors interacting with the LSR element, liver-enriched transcriptional factors, HNF3 and HNF4 or retinoid X receptor alpha (RXR alpha), are probably implicated in the activity of enhancer I for the efficient expression of X gene through their interaction with the LSR element in the hepatic cell. Furthermore, the isolated LSR element was demonstrated to function alone as a specific cis-acting element and to be able to activate transcription from the X gene promoter efficiently in the hepatic cell in an orientation-independent manner.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Binding Sites / genetics
  • Cell Line
  • DNA Probes / genetics
  • DNA, Viral / genetics
  • DNA, Viral / metabolism
  • DNA-Binding Proteins*
  • Enhancer Elements, Genetic*
  • Gene Expression
  • Genes, Viral*
  • Hepatitis B virus / genetics*
  • Hepatitis B virus / metabolism
  • Hepatocyte Nuclear Factor 4
  • Humans
  • Liver / virology
  • Molecular Sequence Data
  • Phosphoproteins / metabolism
  • Point Mutation
  • Promoter Regions, Genetic
  • Receptors, Retinoic Acid / metabolism
  • Retinoid X Receptors
  • Trans-Activators / genetics
  • Transcription Factors / metabolism
  • Transcription, Genetic


  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • DNA Probes
  • DNA, Viral
  • DNA-Binding Proteins
  • Hepatocyte Nuclear Factor 4
  • MLX protein, human
  • Phosphoproteins
  • Receptors, Retinoic Acid
  • Retinoid X Receptors
  • Trans-Activators
  • Transcription Factors
  • hepatitis B virus X protein