Characterization of the hepatitis B virus X- and nucleocapsid gene transcriptional regulatory elements.
The regulatory DNA sequence elements that control the expression of the hepatitis B virus X- and nucleocapsid genes in the differentiated human hepatoma cell lines, Huh7, Hep3B, PLC/PRF/5, and HepG2, the dedifferentiated human hepatoma cell line, HepG2.1, and the human cervical carcinoma cell line, HeLa S3, were analyzed using transient transfection assays. In this system, the hepatitis B virus enhancer I located between coordinates 1071 (-239) and 1238 (-72) increases transcription from the X-gene promoter located between coordinates 1239 (-71) and 1376 (+67) more than 30-fold in the differentiated hepatoma and the HeLa S3 cell lines. In the dedifferentiated hepatoma cell line, HepG2.1, the enhancer I sequence increases the level of transcription from the X-gene promoter approximately 10-fold. The enhancer I subregion between coordinates 1117 (-193) and 1204 (-106) appears to be important for enhancer function only in the differentiated hepatoma cell lines, whereas the enhancer I subregion between coordinates 1222 (-88) and 1238 (-72) is required for enhancer activity in each of the cell lines examined. In all of the cell lines, the X-gene minimal promoter element was within a 138-nucleotide sequence located between coordinates 1239 (-71) and 1376 (+67). The enhancer I sequence increases transcription from the nucleocapsid promoter approximately 3- to 10-fold in the Huh7, Hep3B, PLC/PRF/5, and HeLa S3 cell lines, whereas it had little influence on the level of transcription from this promoter in HepG2 and HepG2.1 cells. The minimal nucleocapsid promoter element was within a 105 nucleotide sequence located between coordinates 1700 (-85) and 1804 (+20). This indicates that the levels of transcription from the X- and nucleocapsid gene promoters are determined in a cell-type-specific manner, in part, by the hepatitis B virus enhancer I and the corresponding minimal promoter sequence.
Zhang
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Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037.
Raney
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AK
McLachlan
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D001483:Base Sequence; D004279:DNA, Viral; D004742:Enhancer Elements, Genetic; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D017384:Sequence Deletion; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D014758:Viral Core Proteins / Q000235:genetics*; D054334:Viral Regulatory and Accessory Proteins
D004279:DNA, Viral; D015534:Trans-Activators; D014758:Viral Core Proteins; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein