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J. Virol., Feb 1997, 1058-1071, Vol 71, No. 2
AK Raney, JL Johnson, CN Palmer and A McLachlan
The role of members of the nuclear receptor superfamily of transcription
factors in regulating hepatitis B virus (HBV) transcription was
investigated. Hepatocyte nuclear factor 4 (HNF4), the retinoid X receptor
(RXR), and the peroxisome proliferator-activated receptor (PPAR) were
examined for their capacity to modulate the level of transcriptional
activity from the four HBV promoters by transient- transfection analysis in
the dedifferentiated hepatoma cell line, HepG2.1. It was found that the
nucleocapsid and large surface antigen promoters were transactivated in the
presence of HNF4 whereas the enhancer I/X gene, nucleocapsid, and large
surface antigen promoters were transactivated in the presence of RXR and
PPAR. Characterization of the nuclear receptors interacting with the
nucleocapsid promoter region demonstrated that HNF4 is the primary
transcription factor binding to the regulatory region spanning nucleotides
-127 to -102 whereas HNF4, RXR-PPAR heterodimers, COUPTF1, and ARP1 bind
the regulatory region spanning nucleotides -34 to -7. Transcriptional
transactivation from the nucleocapsid promoter by HNF4 appears to be
mediated through the two HNF4 binding sites in the promoter, whereas
modulation of the level of transcription from the nucleocapsid promoter by
RXR-PPAR appears to be regulated by the regulatory sequence element
spanning nucleotides -34 to -7 and the HBV enhancer 1 region. These
observations indicate that HBV transcription, and pregenomic RNA synthesis
in particular, is regulated by ligand-dependent nuclear receptors. Agonists
and antagonists capable of regulating the activity of these nuclear
receptors may permit the modulation of HBV transcription and consequently
replication during viral infection.
Copyright © 1997, American Society for Microbiology
Members of the nuclear receptor superfamily regulate transcription from the hepatitis B virus nucleocapsid promoter
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA.
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