Temporal aspects of major viral transcript expression in Hep G2 cells transfected with cloned hepatitis B virus DNA: with emphasis on the X transcript.
The major transcripts of hepatitis B virus (HBV) and the kinetics of their expression were studied in a transient expression system by transfecting partially duplicated copies of HBV genome into Hep G2 cells. By Northern blotting, six species of HBV-specific transcripts could be identified. They were the pregenomic (3.6 kb), the preS1 (2.6 kb), the preS2/S (2.2 kb), the X (0.8 kb), and two spliced (2.2 kb) RNAs, respectively. The preS2/S RNA and the spliced RNAs could be distinguished when a core gene-specific probe, which could not hybridize with the former, was used. Kinetic analysis of the expression of these RNAs revealed that the X transcript exhibited a pattern different from that of other viral transcripts. Amounts of all RNAs peaked at 24-48 hr post-transfection and then gradually declined. However, the X transcript became undetectable on Day 4 post-transfection while other viral RNAs persisted for at least 10 days. The unique expression profile of the X transcript suggested that it probably behaves as an early gene and this is consistent with its proposed role as a transactivator. Nevertheless, frameshift mutations within the X ORF had no obvious effects on the activities and temporal pattern of HBV transcription in this transient expression system.
Wu
H L
HL
Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University Hospital, Taipei.
Chen
P J
PJ
Lin
M H
MH
Chen
D S
DS
D001483:Base Sequence; D015152:Blotting, Northern; D015870:Gene Expression / Q000235:genetics*; D005807:Genes, Overlapping / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D016366:Open Reading Frames / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured; D054334:Viral Regulatory and Accessory Proteins
D012367:RNA, Viral; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein