Project description:Hepatitis B Virus (HBV) is a small DNA virus that replicates via an episomal covalently closed circular DNA (cccDNA) that serves as the transcriptional template for viral mRNAs. The host protein, CCCTC-binding factor (CTCF), is a key regulator of cellular transcription by maintaining epigenetic boundaries, nucleosome phasing, stabilisation of long-range chromatin loops and directing alternative exon splicing. We previously reported that CTCF binds two conserved motifs within Enhancer I of the HBV genome and represses viral transcripts, however, the underlying mechanisms were not identified. We show that CTCF depletion in cells harbouring cccDNA-like HBV molecules and in de novo infected cells resulted in an increase in spliced transcripts, which was most notable in the abundant SP1 spliced transcript. In contrast, depletion of CTCF in cell lines with integrated HBV DNA had no effect on the abundance of viral transcripts and in line with this observation there was limited evidence for CTCF binding to viral integrants, suggesting that CTCF-regulation of HBV transcription is specific to episomal cccDNA. Analysis of HBV chromatin topology by Assay for Transposase Accessibility/sequencing (ATAC-Seq) revealed an accessible region spanning Enhancers I and II and the basal core promoter (BCP). Mutating the CTCF binding sites within Enhancer I resulted in a dramatic rearrangement of chromatin accessibility where the open chromatin region was no longer detected, indicating loss of the phased nucleosome up- and down- stream of the HBV enhancer/BCP. These data demonstrate that CTCF functions to regulate HBV chromatin conformation and nucleosomal positioning in episomal maintained cccDNA, which has important consequences for HBV transcription regulation.
Project description:Hepatitis B Virus (HBV) is a small DNA virus that replicates via an episomal covalently closed circular DNA (cccDNA) that serves as the transcriptional template for viral mRNAs. The host protein, CCCTC-binding factor (CTCF), is a key regulator of cellular transcription by maintaining epigenetic boundaries, nucleosome phasing, stabilisation of long-range chromatin loops and directing alternative exon splicing. We previously reported that CTCF binds two conserved motifs within Enhancer I of the HBV genome and represses viral transcripts, however, the underlying mechanisms were not identified. We show that CTCF depletion in cells harbouring cccDNA-like HBV molecules and in de novo infected cells resulted in an increase in spliced transcripts, which was most notable in the abundant SP1 spliced transcript. In contrast, depletion of CTCF in cell lines with integrated HBV DNA had no effect on the abundance of viral transcripts and in line with this observation there was limited evidence for CTCF binding to viral integrants, suggesting that CTCF-regulation of HBV transcription is specific to episomal cccDNA. Analysis of HBV chromatin topology by Assay for Transposase Accessibility/sequencing (ATAC-Seq) revealed an accessible region spanning Enhancers I and II and the basal core promoter (BCP). Mutating the CTCF binding sites within Enhancer I resulted in a dramatic rearrangement of chromatin accessibility where the open chromatin region was no longer detected, indicating loss of the phased nucleosome up- and down- stream of the HBV enhancer/BCP. These data demonstrate that CTCF functions to regulate HBV chromatin conformation and nucleosomal positioning in episomal maintained cccDNA, which has important consequences for HBV transcription regulation.
Project description:Chronic hepatitis B virus (HBV) infection is an incurable global health threat capable of causing liver disease and hepatocellular carcinoma. During the genesis of infection, HBV establishes an independent chromosome, cccDNA, consisting of the circular viral genome and host histones. The first viral protein expressed, HBx, induces degradation of a host silencing factor to facilitate infection. However, the relationship between cccDNA’s chromatin and early HBx transcription state remains poorly understood. Using reconstituted viral chromosomes, we found that nucleosomes in cccDNA drive HBx transcription. We corroborated these findings in cells and further showed that chromatin destabilizing drugs inhibit viral transcription and antigen expression in hepatocytes. Our results shed new light on a long-standing paradox and represent a novel therapeutic avenue for the treatment of chronic HBV.
Project description:Chronic hepatitis B virus (HBV) infection is an incurable global health threat responsible for causing liver disease and hepatocellular carcinoma. During the genesis of infection, HBV establishes an independent minichromosome consisting of the viral covalently closed circular DNA (cccDNA) genome and host histones. The viral X gene must be expressed immediately upon infection to induce degradation of the host silencing factor, Smc5/6. However, the relationship between cccDNA chromatinization and X gene transcription remains poorly understood. Establishing a reconstituted viral minichromosome platform, we found that nucleosome occupancy in cccDNA drives X transcription. We corroborated these findings in cells and further showed that the chromatin destabilizing molecule CBL137 inhibits X transcription and HBV infection in hepatocytes. Our results shed light on a long-standing paradox and represent a potential new therapeutic avenue for the treatment of chronic HBV infection.
Project description:Curing treatment for HBV infection is yet unavailable, mainly due to unmet gaps in current understanding of the details about HBV-host interaction. By quantitatively assessing HBV-induced global changes in host transcriptome, translatome and proteome, we identified multiple previously unknown transcriptional and translational events that HBV orchestrated to remodel host proteostasis networks and afford micro-environments essential for HBV proliferation and persistence.By delineating novel drug targets and biomarkers in HBV-host interaction, multi-omics interrogation may facilitate the development of next-generation therapeutics or diagnostics against HBV infection and the related maladies.
Project description:Chronic hepatitis B virus (HBV) infection is an incurable global health threat responsible for causing liver disease and hepatocellular carcinoma. During the genesis of infection, HBV establishes an independent minichromosome consisting of the viral covalently closed circular DNA (cccDNA) genome and host histones. The viral X gene must be expressed immediately upon infection to induce degradation of the host silencing factor, Smc5/6. However, the relationship between cccDNA chromatinization and X gene transcription remains poorly understood. Establishing a reconstituted viral minichromosome platform, we found that nucleosome occupancy in cccDNA drives X transcription. We corroborated these findings in cells and further showed that the chromatin destabilizing molecule CBL137 inhibits X transcription and HBV infection in hepatocytes. Our results shed light on a long-standing paradox and represent a potential new therapeutic avenue for the treatment of chronic HBV infection.
Project description:Purpose: Chronic infection with hepatitis B virus is the leading global risk factor for the development of liver cancer. A large body of research has shown the many effects an HBV infection has on cellular physiology, particularly on pathways that may be involved in the development of HBV-associated diseases. Unfortunately, a significant portion of this research has been done in systems that may not mimic what is seen in a primary hepatocyte, and is not done on a transcriptome-wide scale. Because of this, we performed an RNA-seq analysis of primary rat hepatocytes either expressing HBV or not over a series of time points to determine the global changes HBV has on primary hepatocyte physiology. Methods: To do this RNA-seq analysis, triplicate samples of total RNA were collected from cultured primary rat hepatocytes (PRH) over the course of 72hr. PRH were collected immediately after isolation (0hr), or 24hr, 48hr, or 72hr after plating. In addition, PRH were infected 24hr after plating with adenovirus expressing GFP alone (AdGFP) or GFP along with a greater than unit length copy of the HBV genome (AdHBV) and collected at 48hr after plating (24hr after infection) or 72hr after plating (48hr after infection). cDNA libraries were sequenced using the Illumina NextSeq 500 platform to generate either 1x75bp reads. Reads were mapped using the STAR aligner, and output BAMs were further analyzed in R using the GenomicAlignments package, to quantify number of reads per transcript, and DESeq2, to determine differential expression. Reads per kilobase transcript per million total reads (RPKM) was calculated by dividing reads per transcript by the transcript length and then normalizing to the total number of reads in the sample. Results: Following this pipeline, we were able to identify a number of HBV-mediated differentially expressed transcripts at 48hr and 72hr. In addition, we noted considerable change to the hepatocyte transcriptome as a direct result of the isolation/plating procedure, regardless of the presence of HBV. Further pathway analysis of these differentially expressed transcripts identified many important cellular pathways, including those involved with cell cycle regulation and metabolism, as being differentially regulated by HBV in primary hepatocytes. mRNA profiles of cultured primary rat hepatocytes were generated, in triplicate, using the Illumina NextSeq 500 platform from freshly isolated cells (0hr), 24hr, 48hr, or 72hr after plating, and with or without expression of HBV 48hr or 72hr after plating.
Project description:Purpose: Chronic infection with hepatitis B virus is the leading global risk factor for the development of liver cancer. A large body of research has shown the many effects an HBV infection has on cellular physiology, particularly on pathways that may be involved in the development of HBV-associated diseases. Unfortunately, a significant portion of this research has been done in systems that may not mimic what is seen in a primary hepatocyte, and is not done on a transcriptome-wide scale. Because of this, we performed an RNA-seq analysis of primary rat hepatocytes expressing HBV to determine the global changes HBV has on primary hepatocyte physiology. Methods: To do this RNA-seq analysis, triplicate samples of total RNA were collected from cultured primary rat hepatocytes infected with adenovirus expressing GFP alone (AdGFP) or GFP along with a greater than unit length copy of the HBV genome (AdHBV). Samples were collected either 24h or 48h after infection. cDNA libraries were sequenced two times using the Illumina HiSeq or Illumina NextSeq platform to generate either 1x50bp or 1x75bp reads. Reads from each sequencing run were mapped using the STAR aligner, and output BAMs were merged into a single BAM for each sample. The merged BAM was further analyzed in R using the GenomicAlignments package to quantify number of reads per transcript and DESeq2 to determine differential expression. Reads per kilobase transcript per million total reads (RPKM) was calculated by dividing reads per transcript by the transcript length and then normalizing to the total number of reads in the sample. Results: Following this pipeline, we were able to identify a number of HBV-mediated differentially expressed transcripts at 24h and 48h post-infection. Further pathway analysis of these differentially expressed transcripts identified many important cellular pathways, including those involved with cell cycle regulation and metabolism, as being differentially regulated by HBV in primary hepatocytes. mRNA profiles of HBV-expressing and non-expressing primary rat hepatocytes were generated, in triplicate, 24h and 48h post-infection using Illumina HiSeq 2500 and NextSeq 500 instruments.
Project description:Global temporal quantitative proteomic and transcriptomic analysis using long-term hepatitis B virus (HBV)-infected primary human hepatocytes uncovered extensive remodeling of host proteome and transcriptome, and revealed cytopathic effects of long-term viral replication. Metabolic-, complement-, cytoskeleton-, mitochondrial- and oxidation-related pathways were modulated at transcriptional or post-transcriptional levels, which could be partially rescued by early rather than late nucleot(s)ide analogs (NAs) therapy. Overexpression screening identified a series of pro- or anti- HBV host factors. These data have deepened the understanding of the mechanisms of viral pathogenesis and HBV-host interactions in hepatocytes, with implications for therapeutic intervention.
Project description:Phosphorylation is a major post-translation modification (PTM) of proteins, and small molecules, which is finely tuned by the activity of several hundred kinases and phosphatases. It controls most if not all cellular pathways including anti-viral responses. Accordingly, viruses often induce important changes in the phosphorylation of host factors that can either help or counteract viral replication. Surprisingly, among more than 500 kinases constituting the human kinome only few have been described as important for the Hepatitis B virus (HBV) infectious cycle, and most of them intervene during early or late infectious steps by phosphorylating the viral Core protein (HBc) protein. In addition, scarce information is available on the consequences of HBV infection on the activity of cellular kinases. The objective of this study was to investigate the global impact of HBV infection on the cellular phosphorylation landscape at early after infection. For this, primary human hepatocytes (PHH) were challenged or not with HBV, and a mass spectrometry (MS)-based quantitative phospho-proteomic analysis was conducted two- and seven-days post-infection.