IFN-α inhibits HBV transcription and replication in cell culture and in humanized mice by targeting the epigenetic regulation of the nuclear cccDNA minichromosome
Laura Belloni, … , Maura Dandri, Massimo Levrero
Laura Belloni, … , Maura Dandri, Massimo Levrero
Published January 17, 2012
Citation Information: J Clin Invest. 2012;122(2):529-537. https://doi.org/10.1172/JCI58847.
View: Text | PDF
Research Article Virology

IFN-α inhibits HBV transcription and replication in cell culture and in humanized mice by targeting the epigenetic regulation of the nuclear cccDNA minichromosome

Abstract

HBV infection remains a leading cause of death worldwide. IFN-α inhibits viral replication in vitro and in vivo, and pegylated IFN-α is a commonly administered treatment for individuals infected with HBV. The HBV genome contains a typical IFN-stimulated response element (ISRE), but the molecular mechanisms by which IFN-α suppresses HBV replication have not been established in relevant experimental systems. Here, we show that IFN-α inhibits HBV replication by decreasing the transcription of pregenomic RNA (pgRNA) and subgenomic RNA from the HBV covalently closed circular DNA (cccDNA) minichromosome, both in cultured cells in which HBV is replicating and in mice whose livers have been repopulated with human hepatocytes and infected with HBV. Administration of IFN-α resulted in cccDNA-bound histone hypoacetylation as well as active recruitment to the cccDNA of transcriptional corepressors. IFN-α treatment also reduced binding of the STAT1 and STAT2 transcription factors to active cccDNA. The inhibitory activity of IFN-α was linked to the IRSE, as IRSE-mutant HBV transcribed less pgRNA and could not be repressed by IFN-α treatment. Our results identify a molecular mechanism whereby IFN-α mediates epigenetic repression of HBV cccDNA transcriptional activity, which may assist in the development of novel effective therapeutics.

Authors

Laura Belloni, Lena Allweiss, Francesca Guerrieri, Natalia Pediconi, Tassilo Volz, Teresa Pollicino, Joerg Petersen, Giovanni Raimondo, Maura Dandri, Massimo Levrero

×

Figure 5

IFN-α modulates the epigenetic control of cccDNA function by affecting the recruitment of chromatin-modifying enzymes.

Options: View larger image (or click on image) Download as PowerPoint
IFN-α modulates the epigenetic control of cccDNA function by affecting t...
(A) Cross-linked chromatin from untreated and IFN-α–treated HepG2 cells transfected with WT HBV genomes was immunoprecipitated with a relevant control IgG or anti-HDAC1, anti-YY1, anti-hSirt1 and anti-EzH2 antibodies and analyzed as in Figure 1D. (B) HepG2 cells, transfected as in A, were either left untreated (96nt), or treated for 96 hours after transfection with IFN-α (96t), or treated with IFN-α for 48 hours and then left untreated for 48 hours (48t + 48nt). Left panel: cross-linked chromatin immunoprecipitated with a relevant control IgG or anti-Ezh2 antibody was analyzed as in Figure 1D. pgRNA (middle panel) and cytoplasmic core particles HBV-DNA (right panel) were quantified by real-time qPCR. Results are expressed as in Figure 1. (C and D) Chromatin was prepared from untreated and IFN-α–treated HepG2 cells transfected with WT or ISREmt HBV genomes and immunoprecipitated with a relevant control IgG or anti-AcH4 (B) or anti-HDAC1 (C) antibodies. Immunoprecipitated chromatin was analyzed by qPCR and results expressed as in Figure 1D. All histograms show the mean from 3 independent experiments; bars indicate SD. P values were determined using Student’s t test. *P < 0.05; **P < 0.01; ***P < 0.001.