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Harris JM, Magri A, Faria AR, Tsukuda S, Balfe P, Wing PAC, McKeating JA. Oxygen-dependent histone lysine demethylase 4 restricts hepatitis B virus replication. J Biol Chem 2024; 300:105724. [PMID: 38325742 PMCID: PMC10914488 DOI: 10.1016/j.jbc.2024.105724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 01/25/2024] [Accepted: 02/01/2024] [Indexed: 02/09/2024] Open
Abstract
Mammalian cells have evolved strategies to regulate gene expression when oxygen is limited. Hypoxia-inducible factors (HIF) are the major transcriptional regulators of host gene expression. We previously reported that HIFs bind and activate hepatitis B virus (HBV) DNA transcription under low oxygen conditions; however, the global cellular response to low oxygen is mediated by a family of oxygenases that work in concert with HIFs. Recent studies have identified a role for chromatin modifiers in sensing cellular oxygen and orchestrating transcriptional responses, but their role in the HBV life cycle is as yet undefined. We demonstrated that histone lysine demethylase 4 (KDM4) can restrict HBV, and pharmacological or oxygen-mediated inhibition of the demethylase increases viral RNAs derived from both episomal and integrated copies of the viral genome. Sequencing studies demonstrated that KDM4 is a major regulator of the hepatic transcriptome, which defines hepatocellular permissivity to HBV infection. We propose a model where HBV exploits cellular oxygen sensors to replicate and persist in the liver. Understanding oxygen-dependent pathways that regulate HBV infection will facilitate the development of physiologically relevant cell-based models that support efficient HBV replication.
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Affiliation(s)
- James M Harris
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Andrea Magri
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Ana Rita Faria
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Senko Tsukuda
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Peter Balfe
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Peter A C Wing
- Nuffield Department of Medicine, University of Oxford, Oxford, UK; Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, UK.
| | - Jane A McKeating
- Nuffield Department of Medicine, University of Oxford, Oxford, UK; Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, UK.
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Dobrica MO, Varghese CS, Harris JM, Ferguson J, Magri A, Arnold R, Várnai C, Parish JL, McKeating JA. CTCF regulates hepatitis B virus cccDNA chromatin topology. J Gen Virol 2024; 105. [PMID: 38175123 DOI: 10.1099/jgv.0.001939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024] Open
Abstract
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 transcription, 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 Accessible Chromatin 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.
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Affiliation(s)
- Mihaela Olivia Dobrica
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Present address: Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - Christy Susan Varghese
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | | | - Jack Ferguson
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
- Present address: Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Andrea Magri
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Roland Arnold
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Csilla Várnai
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Joanna L Parish
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
- National Institute for Health and Care Research (NIHR) Birmingham Biomedical Research Centre, Oxford, UK
| | - Jane A McKeating
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, UK
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Tsukuda S, Harris JM, Magri A, Balfe P, Wing PAC, Siddiqui A, McKeating JA. The N6-methyladenosine demethylase ALKBH5 regulates the hypoxic HBV transcriptome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.31.564956. [PMID: 37961409 PMCID: PMC10634982 DOI: 10.1101/2023.10.31.564956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Chronic hepatitis B is a global health problem and current treatments only suppress hepatitis B virus (HBV) infection, highlighting the need for new curative treatments. Oxygen levels influence HBV replication and we previously reported that hypoxia inducible factors (HIFs) activate the basal core promoter to transcribe pre-genomic RNA. Application of a probe-enriched long-read sequencing method to map the HBV transcriptome showed an increased abundance of all viral RNAs under low oxygen or hypoxic conditions. Importantly, the hypoxic-associated increase in HBV transcripts was dependent on N6-methyladenosine (m6A) modifications and an m6A DRACH motif in the 5' stem loop of pre-genomic RNA defined transcript half-life under hypoxic conditions. Given the essential role of m6A modifications in the viral transcriptome we assessed the oxygen-dependent expression of RNA demethylases and bioinformatic analysis of published single cell RNA-seq of murine liver showed an increased expression of the RNA demethylase ALKBH5 in the peri-central low oxygen region. In vitro studies with a human hepatocyte derived HepG2 cell line showed increased ALKBH5 gene expression under hypoxic conditions. Silencing the demethylase reduced the levels of HBV pre-genomic RNA and host gene (CA9, NDRG1, VEGFA, BNIP3, FUT11, GAP and P4HA1) transcripts and this was mediated via reduced HIFα expression. In summary, our study highlights a previously unrecognized role for ALKBH5 in orchestrating viral and cellular transcriptional responses to low oxygen.
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Affiliation(s)
- Senko Tsukuda
- Nuffield Department of Medicine, University of Oxford, UK
| | - James M Harris
- Nuffield Department of Medicine, University of Oxford, UK
| | - Andrea Magri
- Nuffield Department of Medicine, University of Oxford, UK
| | - Peter Balfe
- Nuffield Department of Medicine, University of Oxford, UK
| | - Peter AC Wing
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, UK
| | - Aleem Siddiqui
- Division of Infectious Diseases and Global Public Health, University of California, CA, USA
| | - Jane A McKeating
- Nuffield Department of Medicine, University of Oxford, UK
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, UK
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Vachon A, Seo GE, Patel NH, Coffin CS, Marinier E, Eyras E, Osiowy C. Hepatitis B virus serum RNA transcript isoform composition and proportion in chronic hepatitis B patients by nanopore long-read sequencing. Front Microbiol 2023; 14:1233178. [PMID: 37645229 PMCID: PMC10461054 DOI: 10.3389/fmicb.2023.1233178] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 07/31/2023] [Indexed: 08/31/2023] Open
Abstract
Introduction Serum hepatitis B virus (HBV) RNA is a promising new biomarker to manage and predict clinical outcomes of chronic hepatitis B (CHB) infection. However, the HBV serum transcriptome within encapsidated particles, which is the biomarker analyte measured in serum, remains poorly characterized. This study aimed to evaluate serum HBV RNA transcript composition and proportionality by PCR-cDNA nanopore sequencing of samples from CHB patients having varied HBV genotype (gt, A to F) and HBeAg status. Methods Longitudinal specimens from 3 individuals during and following pregnancy (approximately 7 months between time points) were also investigated. HBV RNA extracted from 16 serum samples obtained from 13 patients (73.3% female, 84.6% Asian) was sequenced and serum HBV RNA isoform detection and quantification were performed using three bioinformatic workflows; FLAIR, RATTLE, and a GraphMap-based workflow within the Galaxy application. A spike-in RNA variant (SIRV) control mix was used to assess run quality and coverage. The proportionality of transcript isoforms was based on total HBV reads determined by each workflow. Results All chosen isoform detection workflows showed high agreement in transcript proportionality and composition for most samples. HBV pregenomic RNA (pgRNA) was the most frequently observed transcript isoform (93.8% of patient samples), while other detected transcripts included pgRNA spliced variants, 3' truncated variants and HBx mRNA, depending on the isoform detection method. Spliced variants of pgRNA were primarily observed in HBV gtB, C, E, or F-infected patients, with the Sp1 spliced variant detected most frequently. Twelve other pgRNA spliced variant transcripts were identified, including 3 previously unidentified transcripts, although spliced isoform identification was very dependent on the workflow used to analyze sequence data. Longitudinal sampling among pregnant and post-partum antiviral-treated individuals showed increasing proportions of 3' truncated pgRNA variants over time. Conclusions This study demonstrated long-read sequencing as a promising tool for the characterization of the serum HBV transcriptome. However, further studies are needed to better understand how serum HBV RNA isoform type and proportion are linked to CHB disease progression and antiviral treatment response.
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Affiliation(s)
- Alicia Vachon
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Grace E. Seo
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Nishi H. Patel
- Department of Medicine and Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Carla S. Coffin
- Department of Medicine and Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Eric Marinier
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Eduardo Eyras
- EMBL Australia Partner Laboratory Network at the Australian National University, Canberra, ACT, Australia
- The John Curtin School of Medical Research, ANU College of Health and Medicine, Canberra, ACT, Australia
- Catalan Institution for Research and Advanced Studies, Barcelona, Spain
- Hospital del Mar Medical Research Institute, Barcelona, Spain
| | - Carla Osiowy
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
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