Previous Article | Next Article ![]()
Journal of Virology, December 2001, p. 11354-11364, Vol. 75, No. 23
McArdle Laboratory for Cancer Research,
University of Wisconsin Medical School, Madison, Wisconsin 53706-1599
Received 29 May 2001/Accepted 22 August 2001
Functional analysis of the roles of the nuclear receptor
response elements (NRREs) in the transcription and replication of hepatitis B virus (HBV) in the context of its whole genome has been
hampered by the extensive overlapping of the NRREs with the regions
encoding viral proteins. We introduced point mutations that inactivate
the NRREs individually without altering the open reading frames of
viral proteins. These mutations in the context of a plasmid containing
1.2 copies of the HBV genome were transiently transfected into the
human hepatoma cell line Huh7. Inactivation of the NRRE in either the
preC promoter (NRREpreC) or enhancer I
(NRREenhI) led to moderate reductions in synthesis of viral RNAs. Concurrent inactivation of both NRREs led to 7- to 8-fold reductions in synthesis of the preC, pregenomic, and preS RNAs and a
15-fold reduction in synthesis of the S RNA. The accumulation of viral
DNA in the cytoplasmic nucleocapsids and virion particles in the
culture medium was also reduced seven- to eightfold. These results
suggest that these NRREs are critical for the efficient propagation of
HBV in hepatocytes. In cotransfection experiments we also found that
overexpression of PPAR
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.23.11354-11364.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Critical Roles of Nuclear Receptor Response
Elements in Replication of Hepatitis B Virus
-RXR
in the presence of their respective
ligands led to a fourfold increase in pregenomic RNA synthesis
and a four- to fivefold increase in viral DNA synthesis, while it had
little or no effect on synthesis of the other viral RNAs. Similar
effects were observed with overexpression of PPAR
-RXR
in the
presence of their respective ligands. This activation was dependent on
NRREpreC, because the increase in synthesis of viral RNA
and DNA was not observed when this site was mutated. Likewise, no
activation of synthesis of pregenomic RNA and viral DNA by PPAR
-RXR
was observed in a naturally occurring
NRREpreC
mutant of HBV. Our results suggest
that interactions between nuclear receptors and NRREs present in the
HBV genome may play critical roles in regulating its transcription and
replication during HBV infection of hepatocytes.
*
Corresponding author. Mailing address: McArdle
Laboratory for Cancer Research, University of Wisconsin Medical School,
Madison, WI 53706-1599. Phone: (608)262-2383. Fax: (608)262-2824.
E-mail: mertz{at}oncology.wisc.edu.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»