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Giraud G, El Achi K, Zoulim F, Testoni B. Co-Transcriptional Regulation of HBV Replication: RNA Quality Also Matters. Viruses 2024; 16:615. [PMID: 38675956 PMCID: PMC11053573 DOI: 10.3390/v16040615] [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: 03/25/2024] [Revised: 04/12/2024] [Accepted: 04/15/2024] [Indexed: 04/28/2024] Open
Abstract
Chronic hepatitis B (CHB) virus infection is a major public health burden and the leading cause of hepatocellular carcinoma. Despite the efficacy of current treatments, hepatitis B virus (HBV) cannot be fully eradicated due to the persistence of its minichromosome, or covalently closed circular DNA (cccDNA). The HBV community is investing large human and financial resources to develop new therapeutic strategies that either silence or ideally degrade cccDNA, to cure HBV completely or functionally. cccDNA transcription is considered to be the key step for HBV replication. Transcription not only influences the levels of viral RNA produced, but also directly impacts their quality, generating multiple variants. Growing evidence advocates for the role of the co-transcriptional regulation of HBV RNAs during CHB and viral replication, paving the way for the development of novel therapies targeting these processes. This review focuses on the mechanisms controlling the different co-transcriptional processes that HBV RNAs undergo, and their contribution to both viral replication and HBV-induced liver pathogenesis.
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Affiliation(s)
- Guillaume Giraud
- INSERM U1052, CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, Université Claude Bernard Lyon 1, 69008 Lyon, France (F.Z.)
- The Lyon Hepatology Institute EVEREST, 69003 Lyon, France
| | - Khadija El Achi
- INSERM U1052, CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, Université Claude Bernard Lyon 1, 69008 Lyon, France (F.Z.)
| | - Fabien Zoulim
- INSERM U1052, CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, Université Claude Bernard Lyon 1, 69008 Lyon, France (F.Z.)
- The Lyon Hepatology Institute EVEREST, 69003 Lyon, France
- Hospices Civils de Lyon, Hôpital Croix Rousse, Service d’Hépato-Gastroentérologie, 69004 Lyon, France
| | - Barbara Testoni
- INSERM U1052, CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, Université Claude Bernard Lyon 1, 69008 Lyon, France (F.Z.)
- The Lyon Hepatology Institute EVEREST, 69003 Lyon, France
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2
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Tsukuda S, Harris JM, Magri A, Balfe P, Siddiqui A, Wing PA, McKeating JA. The N6-methyladenosine demethylase ALKBH5 regulates the hypoxic HBV transcriptome. PLoS Pathog 2024; 20:e1011917. [PMID: 38227578 PMCID: PMC10817175 DOI: 10.1371/journal.ppat.1011917] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 01/26/2024] [Accepted: 12/20/2023] [Indexed: 01/18/2024] Open
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 (BCP). Here we show that the hypoxic-dependent increase in BCP-derived transcripts is dependent on N6-methyladenosine (m6A) modifications in the 5' stem loop that regulate RNA half-life. Application of a probe-enriched long-read sequencing method to accurately map the HBV transcriptome showed an increased abundance of pre-genomic RNA under hypoxic conditions. Mapping the transcription start sites of BCP-RNAs identified a role for hypoxia to regulate pre-genomic RNA splicing that is dependent on m6A modification. 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-NTCP cell line showed increased ALKBH5 gene expression under hypoxic conditions and a concomitant reduction in m6A-modified HBV BCP-RNA and host RNAs. Silencing the demethylase reduced the level of BCP-RNAs 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, United Kingdom
| | - James M. Harris
- Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Andrea Magri
- Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Peter Balfe
- Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Aleem Siddiqui
- Department of Medicine, University of California, California, United States of America
| | - Peter A.C. Wing
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, United Kingdom
| | - Jane A. McKeating
- Nuffield Department of Medicine, University of Oxford, United Kingdom
- Department of Medicine, University of California, California, United States of America
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3
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Giraud G, Kim D, Stadelmayer B, Chapus F, Testoni B, Zoulim F. Detection and Quantification of HBV Transcripts by Full-Length 5'RACE-PCR. Methods Mol Biol 2024; 2837:149-158. [PMID: 39044082 DOI: 10.1007/978-1-0716-4027-2_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Chronic hepatitis B virus infection is a major health burden worldwide. Although efficient in maintaining the infection under control, current treatments are unable to fully eradicate the virus due to the persistence of its minichromosome, the so-called cccDNA. In the context of emerging antiviral and combinatorial therapies aiming at decreasing the cccDNA pool or at silencing its transcriptional activity, the detection and quantification of viral RNAs have gained increasing interest as a way to monitor the HBV reservoir. Here, we describe the protocol of the HBV full-length 5'RACE, a technique that allows to define the repertoire of the different HBV RNA species in vitro, intracellularly and extracellularly, and in vivo, in patients' serum in a qualitative or quantitative manner, depending on the choice of the post-analysis methodology.
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Affiliation(s)
- Guillaume Giraud
- Cancer Research Center of Lyon (CRCL), UMR Inserm 1052 CNRS 5286 Mixte, CLB, Université de Lyon 1 (UCBL1), Lyon, France
| | - Doohyun Kim
- Cancer Research Center of Lyon (CRCL), UMR Inserm 1052 CNRS 5286 Mixte, CLB, Université de Lyon 1 (UCBL1), Lyon, France
| | - Bernd Stadelmayer
- Cancer Research Center of Lyon (CRCL), UMR Inserm 1052 CNRS 5286 Mixte, CLB, Université de Lyon 1 (UCBL1), Lyon, France
| | - Fleur Chapus
- Cancer Research Center of Lyon (CRCL), UMR Inserm 1052 CNRS 5286 Mixte, CLB, Université de Lyon 1 (UCBL1), Lyon, France
| | - Barbara Testoni
- Cancer Research Center of Lyon (CRCL), UMR Inserm 1052 CNRS 5286 Mixte, CLB, Université de Lyon 1 (UCBL1), Lyon, France.
| | - Fabien Zoulim
- Cancer Research Center of Lyon (CRCL), UMR Inserm 1052 CNRS 5286 Mixte, CLB, Université de Lyon 1 (UCBL1), Lyon, France.
- Université Claude-Bernard Lyon I, Lyon, France.
- Hepatology Department, Hospices Civils de Lyon, Lyon, France.
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4
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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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5
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Kim SC, Wallin JJ, Ghosheh Y, Zahoor MA, Sanchez Vasquez JD, Nkongolo S, Fung S, Mendez P, Feld JJ, Janssen HL, Gehring AJ. Efficacy of antiviral therapy and host-virus interactions visualised using serial liver sampling with fine-needle aspirates. JHEP Rep 2023; 5:100817. [PMID: 37600958 PMCID: PMC10432215 DOI: 10.1016/j.jhepr.2023.100817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 05/09/2023] [Indexed: 08/22/2023] Open
Abstract
Background & Aims Novel therapies for chronic hepatitis B (CHB), such as RNA interference, target all viral RNAs for degradation, whereas nucleoside analogues are thought to block reverse transcription with minimal impact on viral transcripts. However, limitations in technology and sampling frequency have been obstacles to measuring actual changes in HBV transcription in the liver of patients starting therapy. Methods We used elective liver sampling with fine-needle aspirates (FNAs) to investigate the impact of treatment on viral replication in patients with CHB. Liver FNAs were collected from patients with CHB at baseline and 12 and 24 weeks after starting tenofovir alafenamide treatment. Liver FNAs were subjected to single-cell RNA sequencing and analysed using the Viral-Track method. Results HBV was the only viral genome detected and was enriched within hepatocytes. The 5' sequencing technology identified protein-specific HBV transcripts and showed that tenofovir alafenamide therapy specifically reduced pre-genomic RNA transcripts with little impact on HBsAg or HBx transcripts. Infected hepatocytes displayed unique gene signatures associated with an immunological response to viral infection. Conclusions Longitudinal liver sampling, combined with single-cell RNA sequencing, captured the dynamic impact of antiviral therapy on the replication status of HBV and revealed host-pathogen interactions at the transcriptional level in infected hepatocytes. This sequencing-based approach is applicable to early-stage clinical studies, enabling mechanistic studies of immunopathology and the effect of novel therapeutic interventions. Impact and Implications Infection-dependent transcriptional changes and the impact of antiviral therapy on viral replication can be measured in longitudinal human liver biopsies using single-cell RNA sequencing data.
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Affiliation(s)
| | | | - Yanal Ghosheh
- Toronto Centre for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
| | - Muhammad Atif Zahoor
- Toronto Centre for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
| | - Juan Diego Sanchez Vasquez
- Toronto Centre for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
- Department of Immunology, University of Toronto, Toronto, ON, Canada
| | - Shirin Nkongolo
- Toronto Centre for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
- Department of Internal Medicine IV (Gastroenterology, Hepatology, Infectious Diseases), University Hospital Heidelberg, Heidelberg, Germany
| | - Scott Fung
- Toronto Centre for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
| | | | - Jordan J. Feld
- Toronto Centre for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
| | - Harry L.A. Janssen
- Toronto Centre for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
- Erasmus Medical Center, Division of Gastroenterology and Hepatology, Rotterdam, The Netherlands
| | - Adam J. Gehring
- Toronto Centre for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
- Department of Immunology, University of Toronto, Toronto, ON, Canada
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Villanueva RA, Loyola A. Pre- and Post-Transcriptional Control of HBV Gene Expression: The Road Traveled towards the New Paradigm of HBx, Its Isoforms, and Their Diverse Functions. Biomedicines 2023; 11:1674. [PMID: 37371770 DOI: 10.3390/biomedicines11061674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/04/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
Hepatitis B virus (HBV) is an enveloped DNA human virus belonging to the Hepadnaviridae family. Perhaps its main distinguishable characteristic is the replication of its genome through a reverse transcription process. The HBV circular genome encodes only four overlapping reading frames, encoding for the main canonical proteins named core, P, surface, and X (or HBx protein). However, pre- and post-transcriptional gene regulation diversifies the full HBV proteome into diverse isoform proteins. In line with this, hepatitis B virus X protein (HBx) is a viral multifunctional and regulatory protein of 16.5 kDa, whose canonical reading frame presents two phylogenetically conserved internal in-frame translational initiation codons, and which results as well in the expression of two divergent N-terminal smaller isoforms of 8.6 and 5.8 kDa, during translation. The canonical HBx, as well as the smaller isoform proteins, displays different roles during viral replication and subcellular localizations. In this article, we reviewed the different mechanisms of pre- and post-transcriptional regulation of protein expression that take place during viral replication. We also investigated all the past and recent evidence about HBV HBx gene regulation and its divergent N-terminal isoform proteins. Evidence has been collected for over 30 years. The accumulated evidence simply strengthens the concept of a new paradigm of the canonical HBx, and its smaller divergent N-terminal isoform proteins, not only during viral replication, but also throughout cell pathogenesis.
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Affiliation(s)
| | - Alejandra Loyola
- Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago 8580702, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago 7510602, Chile
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Ng E, Dobrica MO, Harris JM, Wu Y, Tsukuda S, Wing PAC, Piazza P, Balfe P, Matthews PC, Ansari MA, McKeating JA. An enrichment protocol and analysis pipeline for long read sequencing of the hepatitis B virus transcriptome. J Gen Virol 2023; 104:001856. [PMID: 37196057 PMCID: PMC10845048 DOI: 10.1099/jgv.0.001856] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 04/21/2023] [Indexed: 05/19/2023] Open
Abstract
Hepatitis B virus (HBV) is one of the smallest human DNA viruses and its 3.2 Kb genome encodes multiple overlapping open reading frames, making its viral transcriptome challenging to dissect. Previous studies have combined quantitative PCR and Next Generation Sequencing to identify viral transcripts and splice junctions, however the fragmentation and selective amplification used in short read sequencing precludes the resolution of full length RNAs. Our study coupled an oligonucleotide enrichment protocol with state-of-the-art long read sequencing (PacBio) to identify the repertoire of HBV RNAs. This methodology provides sequencing libraries where up to 25 % of reads are of viral origin and enable the identification of canonical (unspliced), non-canonical (spliced) and chimeric viral-human transcripts. Sequencing RNA isolated from de novo HBV infected cells or those transfected with 1.3 × overlength HBV genomes allowed us to assess the viral transcriptome and to annotate 5' truncations and polyadenylation profiles. The two HBV model systems showed an excellent agreement in the pattern of major viral RNAs, however differences were noted in the abundance of spliced transcripts. Viral-host chimeric transcripts were identified and more commonly found in the transfected cells. Enrichment capture and PacBio sequencing allows the assignment of canonical and non-canonical HBV RNAs using an open-source analysis pipeline that enables the accurate mapping of the HBV transcriptome.
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Affiliation(s)
- Esther Ng
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Mihaela-Olivia Dobrica
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Present address: Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - James M. Harris
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Yanxia Wu
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Senko Tsukuda
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Peter A. C. Wing
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, UK
| | - Paolo Piazza
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Peter Balfe
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Philippa C. Matthews
- The Francis Crick Institute, London, UK
- Division of Infection and Immunity, University College London, London, UK
| | - M. Azim Ansari
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
- Peter Medawar Building for Pathogen Research, Nuffield Department of Medicine, 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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Zaiets I, Gunewardena S, Menne S, Weinman SA, Gudima SO. Sera of Individuals Chronically Infected with Hepatitis B Virus (HBV) Contain Diverse RNA Types Produced by HBV Replication or Derived from Integrated HBV DNA. J Virol 2023; 97:e0195022. [PMID: 36877036 PMCID: PMC10062156 DOI: 10.1128/jvi.01950-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 02/11/2023] [Indexed: 03/07/2023] Open
Abstract
This study aimed to better characterize the repertoire of serum hepatitis B virus (HBV) RNAs during chronic HBV infection in humans, which remains understudied. Using reverse transcription-PCR (RT-PCR), real-time quantitative PCR (RT-qPCR), RNA-sequencing, and immunoprecipitation, we found that (i) >50% of serum samples bore different amounts of HBV replication-derived RNAs (rd-RNAs); (ii) a few samples contained RNAs transcribed from integrated HBV DNA, including 5'-HBV-human-3' RNAs (integrant-derived RNAs [id-RNAs]) and 5'-human-HBV-3' transcripts, as a minority of serum HBV RNAs; (iii) spliced HBV RNAs were abundant in <50% of analyzed samples; (iv) most serum rd-RNAs were polyadenylated via conventional HBV polyadenylation signal; (v) pregenomic RNA (pgRNA) was the major component of the pool of serum RNAs; (vi) the area of HBV positions 1531 to 1739 had very high RNA read coverage and thus should be used as a target for detecting serum HBV RNAs; (vii) the vast majority of rd-RNAs and pgRNA were associated with HBV virions but not with unenveloped capsids, exosomes, classic microvesicles, or apoptotic vesicles and bodies; (viii) considerable rd-RNAs presence in the circulating immune complexes was found in a few samples; and (ix) serum relaxed circular DNA (rcDNA) and rd-RNAs should be quantified simultaneously to evaluate HBV replication status and efficacy of anti-HBV therapy with nucleos(t)ide analogs. In summary, sera contain various HBV RNA types of different origin, which are likely secreted via different mechanisms. In addition, since we previously showed that id-RNAs were abundant or predominant HBV RNAs in many of liver and hepatocellular carcinoma tissues as compared to rd-RNAs, there is likely a mechanism favoring the egress of replication-derived RNAs. IMPORTANCE The presence of integrant-derived RNAs (id-RNAs) and 5'-human-HBV-3' transcripts derived from integrated hepatitis B virus (HBV) DNA in sera was demonstrated for the first time. Thus, sera of individuals chronically infected with HBV contained both replication-derived and integrant-transcribed HBV RNAs. The majority of serum HBV RNAs were the transcripts produced by HBV genome replication, which were associated with HBV virions and not with other types of extracellular vesicles. These and other above-mentioned findings advanced our understanding of the HBV life cycle. In addition, the study suggested a promising target area on the HBV genome to increase sensitivity of the detection of serum HBV RNAs and supported the idea that simultaneous detection of replication-derived RNAs (rd-RNAs) and relaxed circular DNA (rcDNA) in serum provides more adequate evaluation of (i) the HBV genome replication status and (ii) the durability and efficiency of the therapy with anti-HBV nucleos(t)ide analogs, which could be useful for improvement of the diagnostics and treatment of HBV-infected individuals.
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Affiliation(s)
- Igor Zaiets
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Sumedha Gunewardena
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Stephan Menne
- Department of Microbiology and Immunology, Georgetown University, Washington, DC, USA
| | - Steven A. Weinman
- Department of Internal Medicine, Division of Gastroenterology, Liver Center, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Severin O. Gudima
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
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Relevance of HBx for Hepatitis B Virus-Associated Pathogenesis. Int J Mol Sci 2023; 24:ijms24054964. [PMID: 36902395 PMCID: PMC10003785 DOI: 10.3390/ijms24054964] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/20/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
The hepatitis B virus (HBV) counts as a major global health problem, as it presents a significant causative factor for liver-related morbidity and mortality. The development of hepatocellular carcinomas (HCC) as a characteristic of a persistent, chronic infection could be caused, among others, by the pleiotropic function of the viral regulatory protein HBx. The latter is known to modulate an onset of cellular and viral signaling processes with emerging influence in liver pathogenesis. However, the flexible and multifunctional nature of HBx impedes the fundamental understanding of related mechanisms and the development of associated diseases, and has even led to partial controversial results in the past. Based on the cellular distribution of HBx-nuclear-, cytoplasmic- or mitochondria-associated-this review encompasses the current knowledge and previous investigations of HBx in context of cellular signaling pathways and HBV-associated pathogenesis. In addition, particular focus is set on the clinical relevance and potential novel therapeutic applications in the context of HBx.
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10
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Nonproductive Hepatitis B Virus Covalently Closed Circular DNA Generates HBx-Related Transcripts from the HBx/Enhancer I Region and Acquires Reactivation by Superinfection in Single Cells. J Virol 2023; 97:e0171722. [PMID: 36475867 PMCID: PMC9888189 DOI: 10.1128/jvi.01717-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hepatitis B virus (HBV) infection remains a public health problem worldwide. Persistent HBV infection relies on active transcription of the covalently closed circular DNA (cccDNA) in hepatocytes, which is less understood at the single-cell level. In this study, we isolated primary human hepatocytes from liver-humanized FRG mice infected with HBV and examined cccDNA transcripts in single cells based on 5' end sequencing. Our 5' transcriptome sequencing (RNA-seq) analysis unambiguously assigns different viral transcripts with overlapping 3' sequences and quantitatively measures viral transcripts for structural genes (3.5 kb, 2.4 kb, and 2.1 kb) and the nonstructural X gene (0.7 kb and related) in single cells. We found that an infected cell either can generate all viral transcripts, signifying active transcription, or presents only transcripts from the X gene and its associated enhancer I domain and no structural gene transcripts. Results from cell infection assays with recombinant HBV show that nonproductive transcription of cccDNA can be activated by incoming virus through superinfection. Moreover, upon HBV infection, cccDNA apparently can be transcribed in the absence of HBx and produces HBx, needed for productive transcription of other viral genes. These results shed new light on cccDNA transcription at the single-cell level and provide insights useful for improving the treatment strategy against chronic HBV infection. IMPORTANCE Hepatitis B virus (HBV) infection can be effectively suppressed but rarely cured by available drugs. Chronic HBV infection is based on persistence of covalently closed circular DNA (cccDNA) and continuous infection and reinfection with HBV in the liver. Understanding transcriptional regulation of cccDNA will help to achieve permanent transcriptional silencing, i.e., functional cure of HBV. In our study, we found that an infected cell either can generate all viral transcripts, signifying active transcription, or presents only transcripts from the X gene and its associated enhancer I domain and no structural gene transcripts. The nonproductive transcription of cccDNA can be activated by incoming virus through superinfection. Upon an infection, cccDNA apparently can be transcribed in the absence of HBx to produce HBx, necessary for subsequent transcription of other HBV genes. Our studies shed new light on the mechanism of HBV infection and may have implications for a functional cure regimen for HBV.
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11
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Kiyose H, Nakagawa H, Ono A, Aikata H, Ueno M, Hayami S, Yamaue H, Chayama K, Shimada M, Wong JH, Fujimoto A. Comprehensive analysis of full-length transcripts reveals novel splicing abnormalities and oncogenic transcripts in liver cancer. PLoS Genet 2022; 18:e1010342. [PMID: 35926060 PMCID: PMC9380957 DOI: 10.1371/journal.pgen.1010342] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 08/16/2022] [Accepted: 07/14/2022] [Indexed: 12/24/2022] Open
Abstract
Genes generate transcripts of various functions by alternative splicing. However, in most transcriptome studies, short-reads sequencing technologies (next-generation sequencers) have been used, leaving full-length transcripts unobserved directly. Although long-reads sequencing technologies would enable the sequencing of full-length transcripts, the data analysis is difficult. In this study, we developed an analysis pipeline named SPLICE and analyzed cDNA sequences from 42 pairs of hepatocellular carcinoma (HCC) and matched non-cancerous livers with an Oxford Nanopore sequencer. Our analysis detected 46,663 transcripts from the protein-coding genes in the HCCs and the matched non-cancerous livers, of which 5,366 (11.5%) were novel. A comparison of expression levels identified 9,933 differentially expressed transcripts (DETs) in 4,744 genes. Interestingly, 746 genes with DETs, including the LINE1-MET transcript, were not found by a gene-level analysis. We also found that fusion transcripts of transposable elements and hepatitis B virus (HBV) were overexpressed in HCCs. In vitro experiments on DETs showed that LINE1-MET and HBV-human transposable elements promoted cell growth. Furthermore, fusion gene detection showed novel recurrent fusion events that were not detected in the short-reads. These results suggest the efficiency of full-length transcriptome studies and the importance of splicing variants in carcinogenesis. Genes generate transcripts of various functions by alternative splicing. However, in most transcriptome studies, short-reads sequencing technologies (next-generation sequencers) have been used, leaving full-length transcripts unobserved directly. In this study, we developed an analysis pipeline named SPLICE for long-read transcriptome sequencing and analyzed cDNA sequences from 42 pairs of hepatocellular carcinoma (HCC), and matched non-cancerous livers with an Oxford Nanopore sequencer. Our analysis detected 5,366 novel transcripts and 9,933 differentially expressed transcripts in 4,744 genes between HCCs and non-cancerous livers. An analysis of hepatitis B virus (HBV) transcripts showed that fusion transcripts of the HBV gene and human transposable elements were overexpressed in HBV-infected HCCs. We also identified fusion genes that were not found in the short-reads. These results suggest that long-reads sequencing technologies provide a fuller understanding of cancer transcripts and that our method contributes to the analysis of transcriptome sequences by such technologies.
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Affiliation(s)
- Hiroki Kiyose
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Drug Discovery Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Hidewaki Nakagawa
- Laboratory for Cancer Genomics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Atsushi Ono
- Department of Gastroenterology and Metabolism, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Hiroshi Aikata
- Department of Gastroenterology and Metabolism, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Masaki Ueno
- Department of Surgery II, Wakayama Medical University, Wakayama, Japan
| | - Shinya Hayami
- Department of Surgery II, Wakayama Medical University, Wakayama, Japan
| | - Hiroki Yamaue
- Department of Surgery II, Wakayama Medical University, Wakayama, Japan
| | - Kazuaki Chayama
- Collaborative Research Laboratory of Medical Innovation, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Research Center for Hepatology and Gastroenterology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Mihoko Shimada
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Jing Hao Wong
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Akihiro Fujimoto
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- * E-mail:
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12
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Skrlec I, Talapko J. Hepatitis B and circadian rhythm of the liver. World J Gastroenterol 2022; 28:3282-3296. [PMID: 36158265 PMCID: PMC9346465 DOI: 10.3748/wjg.v28.i27.3282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/15/2022] [Accepted: 06/17/2022] [Indexed: 02/06/2023] Open
Abstract
The circadian rhythm in humans is determined by the central clock located in the hypothalamus’s suprachiasmatic nucleus, and it synchronizes the peripheral clocks in other tissues. Circadian clock genes and clock-controlled genes exist in almost all cell types. They have an essential role in many physiological processes, including lipid metabolism in the liver, regulation of the immune system, and the severity of infections. In addition, circadian rhythm genes can stimulate the immune response of host cells to virus infection. Hepatitis B virus (HBV) infection is the leading cause of liver disease and liver cancer globally. HBV infection depends on the host cell, and hepatocyte circadian rhythm genes are associated with HBV replication, survival, and spread. The core circadian rhythm proteins, REV-ERB and brain and muscle ARNTL-like protein 1, have a crucial role in HBV replication in hepatocytes. In addition to influencing the virus’s life cycle, the circadian rhythm also affects the pharmacokinetics and efficacy of antiviral vaccines. Therefore, it is vital to apply antiviral therapy at the appropriate time of day to reduce toxicity and improve the effectiveness of antiviral treatment. For these reasons, understanding the role of the circadian rhythm in the regulation of HBV infection and host responses to the virus provides us with a new perspective of the interplay of the circadian rhythm and anti-HBV therapy. Therefore, this review emphasizes the importance of the circadian rhythm in HBV infection and the optimization of antiviral treatment based on the circadian rhythm-dependent immune response.
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Affiliation(s)
- Ivana Skrlec
- Department of Biophysics, Biology, and Chemistry, Faculty of Dental Medicine and Health, J. J. Strossmayer University of Osijek, Osijek 31000, Croatia
| | - Jasminka Talapko
- Department of Anatomy Histology, Embryology, Pathology Anatomy and Pathology Histology, Faculty of Dental Medicine and Health, Osijek 31000, Croatia
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13
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Bustamante-Jaramillo LF, Fingal J, Blondot ML, Rydell GE, Kann M. Imaging of Hepatitis B Virus Nucleic Acids: Current Advances and Challenges. Viruses 2022; 14:v14030557. [PMID: 35336964 PMCID: PMC8950347 DOI: 10.3390/v14030557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/30/2022] [Accepted: 03/01/2022] [Indexed: 11/16/2022] Open
Abstract
Hepatitis B virus infections are the main reason for hepatocellular carcinoma development. Current treatment reduces the viral load but rarely leads to virus elimination. Despite its medical importance, little is known about infection dynamics on the cellular level not at least due to technical obstacles. Regardless of infections leading to extreme viral loads, which may reach 1010 virions per mL serum, hepatitis B viruses are of low abundance and productivity in individual cells. Imaging of the infections in cells is thus a particular challenge especially for cccDNA that exists only in a few copies. The review describes the significance of microscopical approaches on genome and transcript detection for understanding hepatitis B virus infections, implications for understanding treatment outcomes, and recent microscopical approaches, which have not been applied in HBV research.
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Affiliation(s)
- Luisa F. Bustamante-Jaramillo
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; (L.F.B.-J.); (J.F.); (G.E.R.)
| | - Joshua Fingal
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; (L.F.B.-J.); (J.F.); (G.E.R.)
| | - Marie-Lise Blondot
- Microbiologie Fondamentale et Pathogénicité (MFP), CNRS UMR 5234, University of Bordeaux, 33076 Bordeaux, France;
| | - Gustaf E. Rydell
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; (L.F.B.-J.); (J.F.); (G.E.R.)
| | - Michael Kann
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; (L.F.B.-J.); (J.F.); (G.E.R.)
- Region Västra Götaland, Department of Clinical Microbiology, Sahlgrenska University Hospital, 405 30 Gothenburg, Sweden
- Correspondence:
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14
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Broennimann K, Ricardo-Lax I, Adler J, Michailidis E, de Jong YP, Reuven N, Shaul Y. RNR-R2 Upregulation by a Short Non-Coding Viral Transcript. Biomolecules 2021; 11:biom11121822. [PMID: 34944466 PMCID: PMC8698843 DOI: 10.3390/biom11121822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 11/29/2021] [Accepted: 12/01/2021] [Indexed: 01/12/2023] Open
Abstract
DNA viruses require dNTPs for replication and have developed different strategies to increase intracellular dNTP pools. Hepatitis B virus (HBV) infects non-dividing cells in which dNTPs are scarce and the question is how viral replication takes place. Previously we reported that the virus induces the DNA damage response (DDR) pathway culminating in RNR-R2 expression and the generation of an active RNR holoenzyme, the key regulator of dNTP levels, leading to an increase in dNTPs. How the virus induces DDR and RNR-R2 upregulation is not completely known. The viral HBx open reading frame (ORF) was believed to trigger this pathway. Unexpectedly, however, we report here that the production of HBx protein is dispensable. We found that a small conserved region of 125 bases within the HBx ORF is sufficient to upregulate RNR-R2 expression in growth-arrested HepG2 cells and primary human hepatocytes. The observed HBV mRNA embedded regulatory element is named ERE. ERE in isolation is sufficient to activate the ATR-Chk1-E2F1-RNR-R2 DDR pathway. These findings demonstrate a non-coding function of HBV transcripts to support its propagation in non-cycling cells.
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Affiliation(s)
- Karin Broennimann
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel; (K.B.); (I.R.-L.); (J.A.); (N.R.)
| | - Inna Ricardo-Lax
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel; (K.B.); (I.R.-L.); (J.A.); (N.R.)
- Laboratory of Virology and Infectious Disease, Rockefeller University, New York, NY 10065, USA; (E.M.); (Y.P.d.J.)
| | - Julia Adler
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel; (K.B.); (I.R.-L.); (J.A.); (N.R.)
| | - Eleftherios Michailidis
- Laboratory of Virology and Infectious Disease, Rockefeller University, New York, NY 10065, USA; (E.M.); (Y.P.d.J.)
| | - Ype P. de Jong
- Laboratory of Virology and Infectious Disease, Rockefeller University, New York, NY 10065, USA; (E.M.); (Y.P.d.J.)
- Division of Gastroenterology and Hepatology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Nina Reuven
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel; (K.B.); (I.R.-L.); (J.A.); (N.R.)
| | - Yosef Shaul
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel; (K.B.); (I.R.-L.); (J.A.); (N.R.)
- Correspondence: ; Tel.: +972-8-934-2320
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15
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Canonical and Divergent N-Terminal HBx Isoform Proteins Unveiled: Characteristics and Roles during HBV Replication. Biomedicines 2021; 9:biomedicines9111701. [PMID: 34829930 PMCID: PMC8616016 DOI: 10.3390/biomedicines9111701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/11/2021] [Accepted: 11/11/2021] [Indexed: 11/16/2022] Open
Abstract
Hepatitis B virus (HBV) X protein (HBx) is a viral regulatory and multifunctional protein. It is well-known that the canonical HBx reading frame bears two phylogenetically conserved internal in-frame translational initiation codons at Met2 and Met3, thus possibly generating divergent N-terminal smaller isoforms during translation. Here, we demonstrate that the three distinct HBx isoforms are generated from the ectopically expressed HBV HBx gene, named XF (full-length), XM (medium-length), and XS (short-length); they display different subcellular localizations when expressed individually in cultured hepatoma cells. Particularly, the smallest HBx isoform, XS, displayed a predominantly cytoplasmic localization. To study HBx proteins during viral replication, we performed site-directed mutagenesis to target the individual or combinatorial expression of the HBx isoforms within the HBV viral backbone (full viral genome). Our results indicate that of all HBx isoforms, only the smallest HBx isoform, XS, can restore WT levels of HBV replication, and bind to the viral mini chromosome, thereby establishing an active chromatin state, highlighting its crucial activities during HBV replication. Intriguingly, we found that sequences of HBV HBx genotype H are devoid of the conserved Met3 position, and therefore HBV genotype H infection is naturally silent for the expression of the HBx XS isoform. Finally, we found that the HBx XM (medium-length) isoform shares significant sequence similarity with the N-terminus domain of the COMMD8 protein, a member of the copper metabolism MURR1 domain-containing (COMMD) protein family. This novel finding might facilitate studies on the phylogenetic origin of the HBV X protein. The identification and functional characterization of its isoforms will shift the paradigm by changing the concept of HBx from being a unique, canonical, and multifunctional protein toward the occurrence of different HBx isoforms, carrying out different overlapping functions at different subcellular localizations during HBV genome replication. Significantly, our current work unveils new crucial HBV targets to study for potential antiviral research, and human virus pathogenesis.
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16
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Ghosh S, Chakraborty A, Banerjee S. Persistence of Hepatitis B Virus Infection: A Multi-Faceted Player for Hepatocarcinogenesis. Front Microbiol 2021; 12:678537. [PMID: 34526974 PMCID: PMC8435854 DOI: 10.3389/fmicb.2021.678537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/06/2021] [Indexed: 12/14/2022] Open
Abstract
Hepatitis B virus (HBV) infection has a multi-dimensional effect on the host, which not only alters the dynamics of immune response but also persists in the hepatocytes to predispose oncogenic factors. The virus exists in multiple forms of which the nuclear localized covalently closed circular DNA (cccDNA) is the most stable and the primary reason for viral persistence even after clearance of surface antigen and viral DNA. The second reason is the existence of pregenomic RNA (pgRNA) containing virion particles. On the other hand, the integration of the viral genome in the host chromosome also leads to persistent production of viral proteins along with the chromosomal instabilities. The interferon treatment or administration of nucleot(s)ide analogs leads to reduction in the viral DNA load, but the pgRNA and surface antigen clearance are a slow process and complete loss of serological HBsAg is rare. The prolonged exposure of immune cells to the viral antigens, particularly HBs antigen, in the blood circulation results in T-cell exhaustion, which disrupts immune clearance of the virus and virus-infected cells. In addition, it predisposes immune-tolerant microenvironment, which facilitates the tumor progression. Thus cccDNA, pgRNA, and HBsAg along with the viral DNA could be the therapeutic targets in the early disease stages that may improve the quality of life of chronic hepatitis B patients by impeding the progression of the disease toward hepatocellular carcinoma.
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Affiliation(s)
| | | | - Soma Banerjee
- Centre for Liver Research, School of Digestive and Liver Diseases, Institute of Post Graduate Medical Education and Research, Kolkata, India
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17
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D’Arienzo V, Magri A, Harris JM, Wing PAC, Ko C, Rubio CO, Revill PA, Protzer U, Balfe P, McKeating JA. A PCR assay to quantify patterns of HBV transcription. J Gen Virol 2021; 102:001373. [PMID: 31846416 PMCID: PMC7610515 DOI: 10.1099/jgv.0.001373] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 11/27/2019] [Indexed: 12/11/2022] Open
Abstract
Hepatitis B virus (HBV) is the prototype member of the family Hepadnaviridae and replicates via episomal copies of a covalently closed circular DNA (cccDNA) genome of approximately 3.2 kb. The chromatinization of this small viral genome, with overlapping open reading frames and regulatory elements, suggests an important role for epigenetic pathways to regulate HBV transcription. However, the host pathways that regulate HBV transcription and the temporal nature of promoter usage in infected cells are not well understood, in part due to the compact genome structure and overlapping open reading frames. To address this we developed a simple and cost-effective PCR assay to quantify the major viral RNAs and validated this technique using current state-of-art de novo HBV infection model systems. Our PCR method is three orders of magnitude more sensitive than Northern blot and requires relatively small amounts of starting material, making this an attractive tool for assessing HBV transcription.
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Affiliation(s)
- Valentina D’Arienzo
- Nuffield Department of Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, UK
| | - Andrea Magri
- Nuffield Department of Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, UK
| | - James M. Harris
- Nuffield Department of Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, UK
| | - Peter A. C. Wing
- Nuffield Department of Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, UK
| | - Chunkyu Ko
- Institute of Virology, Technische Universität, München/Helmholtz Zentrum München, Germany
| | - Claudia Orbegozo Rubio
- Nuffield Department of Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, UK
| | - Peter A. Revill
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital at the Peter Doherty Institute of Infection and Immunity, Melbourne, Australia
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Australia
| | - Ulrike Protzer
- Institute of Virology, Technische Universität, München/Helmholtz Zentrum München, Germany
- German Center for Infection Research (DZIF), Munich partner site, Munich, Germany
| | - Peter Balfe
- Nuffield Department of Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, UK
- Institute of Immunology and Immunotherapy, University of Birmingham, UK
| | - Jane A. McKeating
- Nuffield Department of Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, UK
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18
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Lim CS, Sozzi V, Littlejohn M, Yuen LK, Warner N, Betz-Stablein B, Luciani F, Revill PA, Brown CM. Quantitative analysis of the splice variants expressed by the major hepatitis B virus genotypes. Microb Genom 2021; 7:mgen000492. [PMID: 33439114 PMCID: PMC8115900 DOI: 10.1099/mgen.0.000492] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/23/2020] [Indexed: 12/13/2022] Open
Abstract
Hepatitis B virus (HBV) is a major human pathogen that causes liver diseases. The main HBV RNAs are unspliced transcripts that encode the key viral proteins. Recent studies have shown that some of the HBV spliced transcript isoforms are predictive of liver cancer, yet the roles of these spliced transcripts remain elusive. Furthermore, there are nine major HBV genotypes common in different regions of the world, these genotypes may express different spliced transcript isoforms. To systematically study the HBV splice variants, we transfected human hepatoma cells, Huh7, with four HBV genotypes (A2, B2, C2 and D3), followed by deep RNA-sequencing. We found that 13-28 % of HBV RNAs were splice variants, which were reproducibly detected across independent biological replicates. These comprised 6 novel and 10 previously identified splice variants. In particular, a novel, singly spliced transcript was detected in genotypes A2 and D3 at high levels. The biological relevance of these splice variants was supported by their identification in HBV-positive liver biopsy and serum samples, and in HBV-infected primary human hepatocytes. Interestingly the levels of HBV splice variants varied across the genotypes, but the spliced pregenomic RNA SP1 and SP9 were the two most abundant splice variants. Counterintuitively, these singly spliced SP1 and SP9 variants had a suboptimal 5' splice site, supporting the idea that splicing of HBV RNAs is tightly controlled by the viral post-transcriptional regulatory RNA element.
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Affiliation(s)
- Chun Shen Lim
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Vitina Sozzi
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Margaret Littlejohn
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Lilly K.W. Yuen
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Nadia Warner
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Brigid Betz-Stablein
- Systems Medicine, School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
- Present address: Dermatology Research Centre, Diamantina Institute, University of Queensland, Brisbane, Queensland, Australia
| | - Fabio Luciani
- Systems Medicine, School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Peter A. Revill
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria, Australia
| | - Chris M. Brown
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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Stadelmayer B, Diederichs A, Chapus F, Rivoire M, Neveu G, Alam A, Fraisse L, Carter K, Testoni B, Zoulim F. Full-length 5'RACE identifies all major HBV transcripts in HBV-infected hepatocytes and patient serum. J Hepatol 2020; 73:40-51. [PMID: 32087349 DOI: 10.1016/j.jhep.2020.01.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 01/10/2020] [Accepted: 01/15/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS Covalently closed circular DNA (cccDNA) is the episomal form of the HBV genome that stably resides in the nucleus of infected hepatocytes. cccDNA is the template for the transcription of 6 major viral RNAs, i.e. preC, pg, preS1/2, S and HBx RNA. All viral transcripts share the same 3' end and are all to various degrees subsets of each other. Especially under infection conditions, it has been difficult to study in depth the transcription of the different viral transcripts. We thus wanted to develop a method with which we could easily detect the full spectrum of viral RNAs in any lab. METHODS We set up an HBV full-length 5'RACE (rapid amplification of cDNA ends) method with which we measured and characterized the full spectrum of viral RNAs in cell culture and in chronically infected patients. RESULTS In addition to canonical HBx transcripts coding for full-length X, we identified shorter HBx transcripts potentially coding for short X proteins. We showed that interferon-β treatment leads to a strong reduction of preC and pgRNAs but has only a moderate effect on the other viral transcripts. We found pgRNA, 1 spliced pgRNA variant and a variety of HBx transcripts associated with viral particles generated by HepAD38 cells. The different HBx RNAs are both capped and uncapped. Lastly, we identified 3 major categories of circulating RNA species in patients with chronic HBV infection: pgRNA, spliced pgRNA variants and HBx. CONCLUSIONS This HBV full-length 5'RACE method should significantly contribute to the understanding of HBV transcription during the course of infection and therapy and may guide the development of novel therapies aimed at targeting cccDNA. LAY SUMMARY Especially under infection conditions, it has been difficult to study the different hepatitis B virus transcripts in depth. This study introduces a new method that can be used in any standard lab to discriminate all hepatitis B viral transcripts in cell culture and in the serum of patients.
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Affiliation(s)
- Bernd Stadelmayer
- INSERM U1052, CNRS UMR-5286, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), 69008 Lyon, France.
| | - Audrey Diederichs
- INSERM U1052, CNRS UMR-5286, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), 69008 Lyon, France
| | - Fleur Chapus
- INSERM U1052, CNRS UMR-5286, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), 69008 Lyon, France
| | - Michel Rivoire
- INSERM U1032, Centre Léon Bérard (CLB), 69008 Lyon, France
| | - Gregory Neveu
- Evotec, 1541 Avenue Marcel Mérieux, 69280 Marcy l'Etoile, France
| | - Antoine Alam
- Evotec, 1541 Avenue Marcel Mérieux, 69280 Marcy l'Etoile, France
| | - Laurent Fraisse
- Evotec, 1541 Avenue Marcel Mérieux, 69280 Marcy l'Etoile, France
| | - Kara Carter
- Evotec, 1541 Avenue Marcel Mérieux, 69280 Marcy l'Etoile, France
| | - Barbara Testoni
- INSERM U1052, CNRS UMR-5286, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), 69008 Lyon, France
| | - Fabien Zoulim
- INSERM U1052, CNRS UMR-5286, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), 69008 Lyon, France; Hospices Civils de Lyon (HCL), 69002 Lyon, France.
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20
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Rivière L, Quioc-Salomon B, Fallot G, Halgand B, Féray C, Buendia MA, Neuveut C. Hepatitis B virus replicating in hepatocellular carcinoma encodes HBx variants with preserved ability to antagonize restriction by Smc5/6. Antiviral Res 2019; 172:104618. [DOI: 10.1016/j.antiviral.2019.104618] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 08/08/2019] [Accepted: 10/05/2019] [Indexed: 12/26/2022]
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21
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Spatiotemporal Analysis of Hepatitis B Virus X Protein in Primary Human Hepatocytes. J Virol 2019; 93:JVI.00248-19. [PMID: 31167911 PMCID: PMC6675897 DOI: 10.1128/jvi.00248-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 05/28/2019] [Indexed: 12/18/2022] Open
Abstract
Hepatitis B virus X protein (HBx) is a promising drug target since it promotes the degradation of the host structural maintenance of chromosomes 5/6 complex (Smc5/6) that inhibits HBV transcription. To date, it has not been possible to study HBx in physiologically relevant cell culture systems due to the lack of a highly specific and selective HBx antibody. In this study, we developed a novel monoclonal HBx antibody and performed a spatiotemporal analysis of HBx in a natural infection system. This revealed that HBx localizes to the nucleus of infected cells, is expressed shortly after infection, and has a short half-life. In addition, we demonstrated that inhibiting HBx expression or function promotes the reappearance of Smc6 in the nucleus of infected cells. These data provide new insights into HBx and underscore its potential as a novel target for the treatment of chronic HBV infection. The structural maintenance of chromosomes 5/6 complex (Smc5/6) is a host restriction factor that suppresses hepatitis B virus (HBV) transcription. HBV counters this restriction by expressing the X protein (HBx), which redirects the host DNA damage-binding protein 1 (DDB1) E3 ubiquitin ligase to target Smc5/6 for degradation. HBx is an attractive therapeutic target for the treatment of chronic hepatitis B (CHB), but it is challenging to study this important viral protein in the context of natural infection due to the lack of a highly specific and sensitive HBx antibody. In this study, we developed a novel monoclonal antibody that enables detection of HBx protein in HBV-infected primary human hepatocytes (PHH) by Western blotting and immunofluorescence. Confocal imaging studies with this antibody demonstrated that HBx is predominantly located in the nucleus of HBV-infected PHH, where it exhibits a diffuse staining pattern. In contrast, a DDB1-binding-deficient HBx mutant was detected in both the cytoplasm and nucleus, suggesting that the DDB1 interaction plays an important role in the nuclear localization of HBx. Our study also revealed that HBx is expressed early after infection and has a short half-life (∼3 h) in HBV-infected PHH. In addition, we found that treatment with small interfering RNAs (siRNAs) that target DDB1 or HBx mRNA decreased HBx protein levels and led to the reappearance of Smc6 in the nuclei of HBV-infected PHH. Collectively, these studies provide the first spatiotemporal analysis of HBx in a natural infection system and also suggest that HBV transcriptional silencing by Smc5/6 can be restored by therapeutic targeting of HBx. IMPORTANCE Hepatitis B virus X protein (HBx) is a promising drug target since it promotes the degradation of the host structural maintenance of chromosomes 5/6 complex (Smc5/6) that inhibits HBV transcription. To date, it has not been possible to study HBx in physiologically relevant cell culture systems due to the lack of a highly specific and selective HBx antibody. In this study, we developed a novel monoclonal HBx antibody and performed a spatiotemporal analysis of HBx in a natural infection system. This revealed that HBx localizes to the nucleus of infected cells, is expressed shortly after infection, and has a short half-life. In addition, we demonstrated that inhibiting HBx expression or function promotes the reappearance of Smc6 in the nucleus of infected cells. These data provide new insights into HBx and underscore its potential as a novel target for the treatment of chronic HBV infection.
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22
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Hepatitis B Virus X Protein Function Requires Zinc Binding. J Virol 2019; 93:JVI.00250-19. [PMID: 31167910 PMCID: PMC6675892 DOI: 10.1128/jvi.00250-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 05/28/2019] [Indexed: 12/18/2022] Open
Abstract
The host structural maintenance of chromosomes 5/6 complex (Smc5/6) suppresses hepatitis B virus (HBV) transcription. HBV counters this restriction by expressing the X protein (HBx), which redirects the cellular DNA damage-binding protein 1 (DDB1)-containing E3 ubiquitin ligase to target Smc5/6 for degradation. However, the details of how HBx modulates the interaction between DDB1 and Smc5/6 remain to be determined. In this study, we performed biophysical analyses of recombinant HBx and functional analysis of HBx mutants in HBV-infected primary human hepatocytes (PHH) to identify key regions and residues that are required for HBx function. We determined that recombinant HBx is soluble and exhibits stoichiometric zinc binding when expressed in the presence of DDB1. Mass spectrometry-based hydrogen-deuterium exchange and cysteine-specific chemical footprinting of the HBx:DDB1 complex identified several HBx cysteine residues (located between amino acids 61 and 137) that are likely involved in zinc binding. These cysteine residues did not form disulfide bonds in HBx expressed in human cells. In line with the biophysical data, functional analysis demonstrated that HBx amino acids 45 to 140 are required for Smc6 degradation and HBV transcription in PHH. Furthermore, site-directed mutagenesis determined that C61, C69, C137, and H139 are necessary for HBx function, although they are likely not essential for DDB1 binding. This CCCH motif is highly conserved in HBV as well as in the X proteins from various mammalian hepadnaviruses. Collectively, our data indicate that the essential HBx cysteine and histidine residues form a zinc-binding motif that is required for HBx function.IMPORTANCE The structural maintenance of chromosomes 5/6 complex (Smc5/6) is a host restriction factor that suppresses HBV transcription. HBV counters this restriction by expressing HBV X protein (HBx), which redirects a host ubiquitin ligase to target Smc5/6 for degradation. Despite this recent advance in understanding HBx function, the key regions and residues of HBx required for Smc5/6 degradation have not been determined. In the present study, we performed biochemical, biophysical, and cell-based analyses of HBx. By doing so, we mapped the minimal functional region of HBx and identified a highly conserved CCCH motif in HBx that is likely responsible for coordinating zinc and is essential for HBx function. We also developed a method to produce soluble recombinant HBx protein that likely adopts a physiologically relevant conformation. Collectively, this study provides new insights into the HBx structure-function relationship and suggests a new approach for structural studies of this enigmatic viral regulatory protein.
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Charre C, Levrero M, Zoulim F, Scholtès C. Non-invasive biomarkers for chronic hepatitis B virus infection management. Antiviral Res 2019; 169:104553. [PMID: 31288041 DOI: 10.1016/j.antiviral.2019.104553] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 07/05/2019] [Accepted: 07/05/2019] [Indexed: 12/12/2022]
Abstract
Chronic hepatitis B virus (HBV) infection remains a major health burden with over 250 million cases worldwide. This complex infection can lead to chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Complete recovery is seldom achieved due to the persistence in infected hepatocytes of covalently closed circular (ccc)DNA, which is not targeted by current antiviral therapies. Routine circulating biomarkers used for clinical monitoring of patients do not accurately reflect the cccDNA pool and transcriptional activity. New biomarkers, such as serum HB core-related Ag and circulating HBV RNAs, are under development. In this review, we discuss surrogate non-invasive biomarkers for evaluating intrahepatic cccDNA abundance and transcriptional activity. We also present their relevance for improving the classification of patients with regards to their natural history and for evaluating novel compounds to assess target engagement and to define new virological endpoints.
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Affiliation(s)
- Caroline Charre
- INSERM U1052-Cancer Research Center of Lyon (CRCL), 69008, Lyon, France; University of Lyon, University Claude Bernard Lyon 1 (UCBL1), Lyon, France; Department of Virology, Croix Rousse Hospital, Hospices Civils de Lyon, Lyon, France
| | - Massimo Levrero
- INSERM U1052-Cancer Research Center of Lyon (CRCL), 69008, Lyon, France; University of Lyon, University Claude Bernard Lyon 1 (UCBL1), Lyon, France; Department of Hepatology, Croix Rousse Hospital, Hospices Civils de Lyon, Lyon, France
| | - Fabien Zoulim
- INSERM U1052-Cancer Research Center of Lyon (CRCL), 69008, Lyon, France; University of Lyon, University Claude Bernard Lyon 1 (UCBL1), Lyon, France; Department of Hepatology, Croix Rousse Hospital, Hospices Civils de Lyon, Lyon, France
| | - Caroline Scholtès
- INSERM U1052-Cancer Research Center of Lyon (CRCL), 69008, Lyon, France; University of Lyon, University Claude Bernard Lyon 1 (UCBL1), Lyon, France; Department of Virology, Croix Rousse Hospital, Hospices Civils de Lyon, Lyon, France.
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Hu J, Cheng J, Tang L, Hu Z, Luo Y, Li Y, Zhou T, Chang J, Guo JT. Virological Basis for the Cure of Chronic Hepatitis B. ACS Infect Dis 2019; 5:659-674. [PMID: 29893548 DOI: 10.1021/acsinfecdis.8b00081] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hepatitis B virus (HBV) has infected one-third of world population, and 240 million people are chronic carriers, to whom a curative therapy is still not available. Similar to other viruses, persistent HBV infection relies on the virus to exploit host cell functions to support its replication and efficiently evade host innate and adaptive antiviral immunity. Understanding HBV replication and concomitant host cell interactions is thus instrumental for development of therapeutics to disrupt the virus-host interactions critical for its persistence and cure chronic hepatitis B. Although the currently available cell culture systems of HBV infection are refractory to genome-wide high throughput screening of key host cellular factors essential for and/or regulating HBV replication, classic one-gene (or pathway)-at-a-time studies in the last several decades have already revealed many aspects of HBV-host interactions. An overview of the landscape of HBV-hepatocyte interaction indicates that, in addition to more tightly suppressing viral replication by directly targeting viral proteins, disruption of key viral-host cell interactions to eliminate or inactivate the covalently closed circular (ccc) DNA, the most stable HBV replication intermediate that exists as an episomal minichromosome in the nucleus of infected hepatocyte, is essential to achieve a functional cure of chronic hepatitis B. Moreover, therapeutic targeting of integrated HBV DNA and their transcripts may also be required to induce hepatitis B virus surface antigen (HBsAg) seroclearance and prevent liver carcinogenesis.
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Affiliation(s)
- Jin Hu
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Science, 1 Tian-tan Xi-li, Beijing, 100050, China
| | - Junjun Cheng
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Liudi Tang
- Microbiology and Immunology Graduate Program, Drexel University College of Medicine, 2900 West Queen Lane, Philadelphia, Pennsylvania 19129, United States
| | - Zhanying Hu
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Yue Luo
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
- Institute of Hepatology, Second Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan 410008, China
| | - Yuhuan Li
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Science, 1 Tian-tan Xi-li, Beijing, 100050, China
| | - Tianlun Zhou
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Jinhong Chang
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Ju-Tao Guo
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
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Mapping the Heterogeneity of Histone Modifications on Hepatitis B Virus DNA Using Liver Needle Biopsies Obtained from Chronically Infected Patients. J Virol 2019; 93:JVI.02036-18. [PMID: 30787147 DOI: 10.1128/jvi.02036-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/01/2019] [Indexed: 12/20/2022] Open
Abstract
Covalently closed circular DNA (cccDNA) forms the basis for replication and persistence of hepatitis B virus (HBV) in the chronically infected liver. We have previously shown that viral transcription is subject to regulation by posttranslational modifications (PTMs) of histone proteins bound to cccDNA through analysis of de novo HBV-infected cell lines. We now report the successful adaptation of this chromatin immunoprecipitation sequencing (ChIPseq) approach for analysis of fine-needle patient liver biopsy specimens to investigate the role of histone PTMs in chronically HBV-infected patients. Using 18 specimens from patients in different stages of chronic HBV infection, our work shows that the profile of histone PTMs in chronic infection is more nuanced than previously observed in in vitro models of acute infection. In line with our previous findings, we find that the majority of HBV-derived sequences are associated with the activating histone PTM H3K4me3. However, we show a striking interpatient variability of its deposition in this patient cohort correlated with viral transcription and patient HBV early antigen (HBeAg) status. Unexpectedly, we detected deposition of the classical inhibitory histone PTM H3K9me3 on HBV-DNA in around half of the patient biopsy specimens, which could not be linked to reduced levels of viral transcripts. Our results show that current in vitro models are unable to fully recapitulate the complex epigenetic landscape of chronic HBV infection observed in vivo and demonstrate that fine-needle liver biopsy specimens can provide sufficient material to further investigate the interaction of viral and host proteins on HBV-DNA.IMPORTANCE Hepatitis B virus (HBV) is a major global health concern, chronically infecting millions of patients and contributing to a rising burden of liver disease. The viral genome forms the basis for chronic infection and has been shown to be subject to regulation by epigenetic mechanisms, such as posttranslational modification of histone proteins. Here, we confirm and expand on previous results by adapting a high-resolution technique for analysis of histone modifications for use with patient-derived fine-needle liver biopsy specimens. Our work highlights that the situation in vivo is more complex than predicted by current in vitro models, for example, by suggesting a novel, noncanonical role of the histone modification H3K9me3 in the HBV life cycle. Importantly, enabling the use of fine-needle liver biopsy specimens for such high-resolution analyses may facilitate further research into the epigenetic regulation of the HBV genome.
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Niu C, Livingston CM, Li L, Beran RK, Daffis S, Ramakrishnan D, Burdette D, Peiser L, Salas E, Ramos H, Yu M, Cheng G, Strubin M, Delaney IV WE, Fletcher SP. The Smc5/6 Complex Restricts HBV when Localized to ND10 without Inducing an Innate Immune Response and Is Counteracted by the HBV X Protein Shortly after Infection. PLoS One 2017; 12:e0169648. [PMID: 28095508 PMCID: PMC5240991 DOI: 10.1371/journal.pone.0169648] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/20/2016] [Indexed: 02/06/2023] Open
Abstract
The structural maintenance of chromosome 5/6 complex (Smc5/6) is a restriction factor that represses hepatitis B virus (HBV) transcription. HBV counters this restriction by expressing HBV X protein (HBx), which targets Smc5/6 for degradation. However, the mechanism by which Smc5/6 suppresses HBV transcription and how HBx is initially expressed is not known. In this study we characterized viral kinetics and the host response during HBV infection of primary human hepatocytes (PHH) to address these unresolved questions. We determined that Smc5/6 localizes with Nuclear Domain 10 (ND10) in PHH. Co-localization has functional implications since depletion of ND10 structural components alters the nuclear distribution of Smc6 and induces HBV gene expression in the absence of HBx. We also found that HBV infection and replication does not induce a prominent global host transcriptional response in PHH, either shortly after infection when Smc5/6 is present, or at later times post-infection when Smc5/6 has been degraded. Notably, HBV and an HBx-negative virus establish high level infection in PHH without inducing expression of interferon-stimulated genes or production of interferons or other cytokines. Our study also revealed that Smc5/6 is degraded in the majority of infected PHH by the time cccDNA transcription could be detected and that HBx RNA is present in cell culture-derived virus preparations as well as HBV patient plasma. Collectively, these data indicate that Smc5/6 is an intrinsic antiviral restriction factor that suppresses HBV transcription when localized to ND10 without inducing a detectable innate immune response. Our data also suggest that HBx protein may be initially expressed by delivery of extracellular HBx RNA into HBV-infected cells.
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Affiliation(s)
- Congrong Niu
- Gilead Sciences, Foster City, California, United States of America
| | | | - Li Li
- Gilead Sciences, Foster City, California, United States of America
| | - Rudolf K. Beran
- Gilead Sciences, Foster City, California, United States of America
| | - Stephane Daffis
- Gilead Sciences, Foster City, California, United States of America
| | | | - Dara Burdette
- Gilead Sciences, Foster City, California, United States of America
| | - Leanne Peiser
- Gilead Sciences, Foster City, California, United States of America
| | - Eduardo Salas
- Gilead Sciences, Foster City, California, United States of America
| | - Hilario Ramos
- Gilead Sciences, Foster City, California, United States of America
| | - Mei Yu
- Gilead Sciences, Foster City, California, United States of America
| | - Guofeng Cheng
- Gilead Sciences, Foster City, California, United States of America
| | - Michel Strubin
- Department of Microbiology and Molecular Medicine, University Medical Center (C.M.U.), Geneva, Switzerland
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