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Title

Hepatitis B virus x protein stimulates gene expression selectively from extrachromosomal DNA templates

Authors
Zoulim, Fabien
Hantz, Olivier
Published in Hepatology. 2012
Abstract Chronic hepatitis B virus (HBV) infection is a major risk factor for liver cancer development. HBV encodes the hepatitis B virus X (HBx) protein that promotes transcription of the viral episomal DNA genome by the host cell RNA polymerase II. Here we provide evidence that HBx accomplishes this task by a conserved and unusual mechanism. Thus, HBx strongly stimulates expression of transiently transfected reporter constructs, regardless of the enhancer and promoter sequences. This activity invariably requires HBx binding to the cellular UV-damaged DDB1 E3 ubiquitin ligase, suggesting a common mechanism. Unexpectedly, none of the reporters tested is stimulated by HBx when integrated into the chromosome, despite remaining responsive to their cognate activators. Likewise, HBx promotes gene expression from the natural HBV episomal template but not from a chromosomally integrated HBV construct. The same was observed with the HBx protein of woodchuck HBV. HBx does not affect nuclear plasmid copy number and functions independently of CpG dinucleotide methylation. Conclusion: We propose that HBx supports HBV gene expression by a conserved mechanism that acts specifically on episomal DNA templates independently of the nature of the cis-regulatory sequences. Because of its uncommon property and key role in viral transcription, HBx represents an attractive target for new antiviral therapies. (HEPATOLOGY 2012).
Identifiers
PMID: 22744635
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Article (Published version) (640 Kb) - document accessible for UNIGE members only Limited access to UNIGE
Structures
Research group Régulation de l'expression des gènes du virus de l'hépatite B (294)
Project FNS: 31003A-127384
Citation
(ISO format)
VAN BREUGEL, Pieter Cornelis et al. Hepatitis B virus x protein stimulates gene expression selectively from extrachromosomal DNA templates. In: Hepatology, 2012. https://archive-ouverte.unige.ch/unige:24257

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Deposited on : 2012-11-30

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