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Hepatitis B virus DNA contains a glucocorticoid-responsive element
Summary
Hepatitis B virus (HBV) DNA contains a glucocorticoid-responsive element. This element influences HBV gene expression in infected cells, distinct from the previously identified enhancer.
Area of Science:
- Virology
- Molecular Biology
- Hepatology
Background:
- Hepatitis B virus (HBV) possesses a transcriptional enhancer element.
- Glucocorticoids are potent regulators of gene expression in mammalian cells.
Purpose of the Study:
- To investigate if the HBV enhancer responds to glucocorticoids.
- To identify the specific HBV DNA sequences involved in glucocorticoid regulation.
Main Methods:
- Construction of pA10CAT2 plasmid derivatives with HBV enhancer and upstream sequences.
- Transient expression assays of chloramphenicol acetyltransferase (CAT) in various cell lines (PLC/PRF/5, Hep 3B, Hep G2, HeLa, mouse L).
- Dose-response analysis of dexamethasone-induced CAT expression.
Main Results:
- Dexamethasone significantly augmented CAT expression (3- to 8-fold) in all tested cell lines.
- Maximal induction by dexamethasone occurred at 1 microM, with significant effects at 10 nM.
- Glucocorticoid responsiveness was observed only with constructs containing HBV DNA upstream of map position 735.
Conclusions:
- HBV DNA harbors a distinct glucocorticoid-responsive element (GRE).
- This GRE is located separately from the previously defined HBV enhancer region.
- The identified GRE may play a role in regulating HBV gene expression in infected cells.