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Hofmann S, Luther J, Plank V, Oswald A, Mai J, Simons I, Miller J, Falcone V, Hansen-Palmus L, Hengel H, Nassal M, Protzer U, Schreiner S. Arsenic trioxide impacts hepatitis B virus core nuclear localization and efficiently interferes with HBV infection. Microbiol Spectr 2024; 12:e0378823. [PMID: 38567974 PMCID: PMC11064512 DOI: 10.1128/spectrum.03788-23] [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: 10/30/2023] [Accepted: 03/14/2024] [Indexed: 05/03/2024] Open
Abstract
The key to a curative treatment of hepatitis B virus (HBV) infection is the eradication of the intranuclear episomal covalently closed circular DNA (cccDNA), the stable persistence reservoir of HBV. Currently, established therapies can only limit HBV replication but fail to tackle the cccDNA. Thus, novel therapeutic approaches toward curative treatment are urgently needed. Recent publications indicated a strong association between the HBV core protein SUMOylation and the association with promyelocytic leukemia nuclear bodies (PML-NBs) on relaxed circular DNA to cccDNA conversion. We propose that interference with the cellular SUMOylation system and PML-NB integrity using arsenic trioxide provides a useful tool in the treatment of HBV infection. Our study showed a significant reduction in HBV-infected cells, core protein levels, HBV mRNA, and total DNA. Additionally, a reduction, albeit to a limited extent, of HBV cccDNA could be observed. Furthermore, this interference was also applied for the treatment of an established HBV infection, characterized by a stably present nuclear pool of cccDNA. Arsenic trioxide (ATO) treatment not only changed the amount of expressed HBV core protein but also induced a distinct relocalization to an extranuclear phenotype during infection. Moreover, ATO treatment resulted in the redistribution of transfected HBV core protein away from PML-NBs, a phenotype similar to that previously observed with SUMOylation-deficient HBV core. Taken together, these findings revealed the inhibition of HBV replication by ATO treatment during several steps of the viral replication cycle, including viral entry into the nucleus as well as cccDNA formation and maintenance. We propose ATO as a novel prospective treatment option for further pre-clinical and clinical studies against HBV infection. IMPORTANCE The main challenge for the achievement of a functional cure for hepatitis B virus (HBV) is the covalently closed circular DNA (cccDNA), the highly stable persistence reservoir of HBV, which is maintained by further rounds of infection with newly generated progeny viruses or by intracellular recycling of mature nucleocapsids. Eradication of the cccDNA is considered to be the holy grail for HBV curative treatment; however, current therapeutic approaches fail to directly tackle this HBV persistence reservoir. The molecular effect of arsenic trioxide (ATO) on HBV infection, protein expression, and cccDNA formation and maintenance, however, has not been characterized and understood until now. In this study, we reveal ATO treatment as a novel and innovative therapeutic approach against HBV infections, repressing viral gene expression and replication as well as the stable cccDNA pool at low micromolar concentrations by affecting the cellular function of promyelocytic leukemia nuclear bodies.
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Affiliation(s)
- Samuel Hofmann
- Institute of Virology, School of Medicine, Technical University of Munich, Munich, Germany
- Institute of Virology, Hannover Medical School, Hannover, Germany
- Cluster of Excellence RESIST (Resolving Infection Susceptibility, EXC 2155), Hannover Medical School, Hannover, Germany
- Division of Pediatric Neurology and Metabolic Medicine, Center for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Julius Luther
- Institute of Virology, Hannover Medical School, Hannover, Germany
- Cluster of Excellence RESIST (Resolving Infection Susceptibility, EXC 2155), Hannover Medical School, Hannover, Germany
| | - Verena Plank
- Institute of Virology, School of Medicine, Technical University of Munich, Munich, Germany
| | - Andreas Oswald
- Institute of Virology, School of Medicine, Technical University of Munich, Munich, Germany
| | - Julia Mai
- Institute of Virology, Hannover Medical School, Hannover, Germany
- Cluster of Excellence RESIST (Resolving Infection Susceptibility, EXC 2155), Hannover Medical School, Hannover, Germany
- Department of Internal Medicine II/Molecular Biology, University Hospital Freiburg, Freiburg, Germany
| | - Ilka Simons
- Institute of Virology, Hannover Medical School, Hannover, Germany
- Cluster of Excellence RESIST (Resolving Infection Susceptibility, EXC 2155), Hannover Medical School, Hannover, Germany
| | - Julija Miller
- Department of Internal Medicine II/Molecular Biology, University Hospital Freiburg, Freiburg, Germany
| | - Valeria Falcone
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
| | - Lea Hansen-Palmus
- Institute of Virology, School of Medicine, Technical University of Munich, Munich, Germany
| | - Hartmut Hengel
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
| | - Michael Nassal
- Department of Internal Medicine II/Molecular Biology, University Hospital Freiburg, Freiburg, Germany
| | - Ulrike Protzer
- Institute of Virology, School of Medicine, Technical University of Munich, Munich, Germany
- Institute of Virology, Helmholtz Zentrum München, Munich, Germany
- German Center for Infection Research (DZIF), Munich, Germany
| | - Sabrina Schreiner
- Institute of Virology, School of Medicine, Technical University of Munich, Munich, Germany
- Institute of Virology, Hannover Medical School, Hannover, Germany
- Cluster of Excellence RESIST (Resolving Infection Susceptibility, EXC 2155), Hannover Medical School, Hannover, Germany
- Institute of Virology, Medical Center – University of Freiburg, Freiburg, Germany
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2
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Su Y, Bu F, Zhu Y, Yang L, Wu Q, Zheng Y, Zhao J, Yu L, Jiang N, Wang Y, Wu J, Xie Y, Zhang X, Gao Y, Lan K, Deng Q. Hepatitis B virus core protein as a Rab-GAP suppressor driving liver disease progression. Sci Bull (Beijing) 2024:S2095-9273(24)00248-2. [PMID: 38670853 DOI: 10.1016/j.scib.2024.04.014] [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: 11/14/2023] [Revised: 02/28/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024]
Abstract
Chronic hepatitis B virus (HBV) infection can lead to advanced liver pathology. Here, we establish a transgenic murine model expressing a basic core promoter (BCP)-mutated HBV genome. Unlike previous studies on the wild-type virus, the BCP-mutated HBV transgenic mice manifest chronic liver injury that culminates in cirrhosis and tumor development with age. Notably, agonistic anti-Fas treatment induces fulminant hepatitis in these mice even at a negligible dose. As the BCP mutant exhibits a striking increase in HBV core protein (HBc) expression, we posit that HBc is actively involved in hepatocellular injury. Accordingly, HBc interferes with Fis1-stimulated mitochondrial recruitment of Tre-2/Bub2/Cdc16 domain family member 15 (TBC1D15). HBc may also inhibit multiple Rab GTPase-activating proteins, including Rab7-specific TBC1D15 and TBC1D5, by binding to their conserved catalytic domain. In cells under mitochondrial stress, HBc thus perturbs mitochondrial dynamics and prevents the recycling of damaged mitochondria. Moreover, sustained HBc expression causes lysosomal consumption via Rab7 hyperactivation, which further hampers late-stage autophagy and substantially increases apoptotic cell death. Finally, we show that adenovirally expressed HBc in a mouse model is directly cytopathic and causes profound liver injury, independent of antigen-specific immune clearance. These findings reveal an unexpected cytopathic role of HBc, making it a pivotal target for HBV-associated liver disease treatment. The BCP-mutated HBV transgenic mice also provide a valuable model for understanding chronic hepatitis B progression and for the assessment of therapeutic strategies.
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Affiliation(s)
- Yu Su
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China
| | - Fan Bu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China
| | - Yuanfei Zhu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China; Laboratory of Cellular Immunity, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Le Yang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China
| | - Qiong Wu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China
| | - Yuan Zheng
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China
| | - Jianjin Zhao
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China
| | - Lin Yu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China
| | - Nan Jiang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China
| | - Yongxiang Wang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China
| | - Jian Wu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China
| | - Youhua Xie
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China
| | - Xinxin Zhang
- Department of Infectious Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yueqiu Gao
- Laboratory of Cellular Immunity, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
| | - Ke Lan
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
| | - Qiang Deng
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity, Fudan University, Shanghai 200032, China; Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Fudan University, Shanghai 200032, China.
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3
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Elizalde MM, Giadans CG, Campos RH, Flichman DM. Impact of core protein naturally selected mutants associated with HBeAg-negative status in HBV biosynthesis. J Med Virol 2023; 95:e29195. [PMID: 37881005 DOI: 10.1002/jmv.29195] [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] [Received: 07/12/2023] [Revised: 10/04/2023] [Accepted: 10/11/2023] [Indexed: 10/27/2023]
Abstract
Hepatitis B e antigen (HBeAg) loss represents a late stage of chronic hepatitis B virus (HBV) infection associated with a drastic decrease in HBV-DNA, a lower risk of disease progression, and the occurrence of several mutations in the preCore/core region. However, the underlying mechanisms supporting the downregulation of viral replication have yet to be elucidated. In the present study, the analysis of the frequency of subgenotype D1 core protein (HBc) mutations associated with HBeAg status revealed a higher mutation rate in HBeAg-negative sequences compared to HBeAg-positive ones. Particularly, 22 amino acids exhibited a higher frequency of mutation in HBeAg-negative sequences, while the remaining residues showed a high degree of conservation. Subsequently, the assessment of HBc mutants derived from HBeAg-negative patients in viral structure and replicative capacity revealed that HBc mutations have the ability to modulate the subcellular localization of the protein (either when the protein was expressed alone or in the context of viral replication), capsid assembly, and, depending on specific mutation patterns, alter covalently closed circular DNA (cccDNA) recycling and up- or downregulate viral replication. In conclusion, HBc mutations associated with HBeAg-negative status impact on various stages of the HBV life cycle modulating viral replication during the HBeAg-negative stage of infection.
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Affiliation(s)
- María Mercedes Elizalde
- Facultad de Medicina, Departamento de Microbiología, Parasitología e Inmunología, Instituto de Investigaciones Biomédicas en Retrovirus y Sida (INBIRS), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Cecilia Graciela Giadans
- Facultad de Medicina, Departamento de Microbiología, Parasitología e Inmunología, Instituto de Investigaciones Biomédicas en Retrovirus y Sida (INBIRS), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Rodolfo Héctor Campos
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Departamento de Microbiología, Inmunología, Biotecnología y Genética, Cátedra de Virología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Diego Martín Flichman
- Facultad de Medicina, Departamento de Microbiología, Parasitología e Inmunología, Instituto de Investigaciones Biomédicas en Retrovirus y Sida (INBIRS), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
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4
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Duchemin NJ, Loonawat R, Yeakle K, Rosenkranz A, Bouchard MJ. Hypoxia-inducible factor affects hepatitis B virus transcripts and genome levels as well as the expression and subcellular location of the hepatitis B virus core protein. Virology 2023; 586:76-90. [PMID: 37490813 DOI: 10.1016/j.virol.2023.06.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 06/13/2023] [Accepted: 06/21/2023] [Indexed: 07/27/2023]
Abstract
Globally, a chronic-hepatitis B virus (HBV) infection is the leading cause of hepatocellular carcinoma (HCC). The transcription factor hypoxia-inducible factor 1 (HIF1) is often elevated in HCC, including HBV-associated HCC. Previous studies have suggested that the expression of the HIF1 subunit, HIF1α, is elevated in HBV-infected hepatocytes; however, whether HIF1 activity affects the HBV lifecycle has not been fully explored. We used a liver-derived cell line and ex vivo cultured primary hepatocytes as models to determine how HIF1 affects the HBV lifecycle. We observed that HIF1 elevates HBV RNA transcript levels, core protein levels, core protein localization to the cytoplasm, and HBV genome replication. Attenuating the transcription activity of HIF1 blocked HIF1-mediated effects on the HBV lifecycle. Our studies show that HIF1 regulates various stages of the HBV lifecycle in hepatocytes and could be a therapeutic target for blocking HBV replication and the development of HBV-associated diseases.
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Affiliation(s)
- Nicholas J Duchemin
- Molecular and Cellular Biology and Genetic Graduate Program, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, USA
| | - Ronak Loonawat
- Microbiology and Immunology Graduate Program, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, USA
| | - Kyle Yeakle
- Molecular and Cellular Biology and Genetic Graduate Program, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, USA
| | - Andrea Rosenkranz
- Molecular and Cellular Biology and Genetic Graduate Program, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, USA
| | - Michael J Bouchard
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, 19102, USA.
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5
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Zheng Y, Yang L, Yu L, Zhu Y, Wu Y, Zhang Z, Xia T, Deng Q. Canocapavir Is a Novel Capsid Assembly Modulator Inducing a Conformational Change of the Linker Region of HBV Core Protein. Viruses 2023; 15:v15051195. [PMID: 37243280 DOI: 10.3390/v15051195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 05/11/2023] [Accepted: 05/15/2023] [Indexed: 05/28/2023] Open
Abstract
Canocapavir is a novel antiviral agent with characteristics of core protein allosteric modulators (CpAMs) that is currently in a phase II clinical trial for treatment of hepatitis B virus (HBV) infection. Herein, we show that Canocapavir prevented the encapsidation of HBV pregenomic RNA and increased the accumulation of cytoplasmic empty capsids, presumably by targeting the hydrophobic pocket at the dimer-dimer interface of HBV core protein (HBc). Canocapavir treatment markedly reduced the egress of naked capsids, which could be reversed by Alix overexpression through a mechanism other than direct association of Alix with HBc. Moreover, Canocapavir interfered with the interaction between HBc and HBV large surface protein, resulting in diminished production of empty virions. Of particular note, Canocapavir induced a conformational change of capsids, with the C-terminus of HBc linker region fully exposed on the exterior of capsids. We posit that the allosteric effect may have great importance in the anti-HBV activity of Canocapavir, given the emerging virological significance of HBc linker region. In support of this notion, the mutation at HBc V124W typically recapitulated the conformational change of the empty capsid with aberrant cytoplasmic accumulation. Collectively, our results indicate Canocapavir as a mechanistically distinct type of CpAMs against HBV infection.
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Affiliation(s)
- Yuan Zheng
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai 200032, China
| | - Le Yang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai 200032, China
| | - Lin Yu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai 200032, China
| | - Yuanfei Zhu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai 200032, China
| | - Yang Wu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Zhijun Zhang
- Shanghai Zhimeng Biopharma, Inc., 1976 Gaoke Middle Road, Suite A-302, Pudong District, Shanghai 201210, China
| | - Tian Xia
- Shanghai Zhimeng Biopharma, Inc., 1976 Gaoke Middle Road, Suite A-302, Pudong District, Shanghai 201210, China
| | - Qiang Deng
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai 200032, China
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6
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Romero S, Unchwaniwala N, Evans EL, Eliceiri KW, Loeb DD, Sherer NM. Live Cell Imaging Reveals HBV Capsid Translocation from the Nucleus To the Cytoplasm Enabled by Cell Division. mBio 2023; 14:e0330322. [PMID: 36809075 PMCID: PMC10127671 DOI: 10.1128/mbio.03303-22] [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: 11/29/2022] [Accepted: 01/17/2023] [Indexed: 02/23/2023] Open
Abstract
Hepatitis B virus (HBV) capsid assembly is traditionally thought to occur predominantly in the cytoplasm, where the virus gains access to the virion egress pathway. To better define sites of HBV capsid assembly, we carried out single cell imaging of HBV Core protein (Cp) subcellular trafficking over time under conditions supporting genome packaging and reverse transcription in Huh7 hepatocellular carcinoma cells. Time-course analyses including live cell imaging of fluorescently tagged Cp derivatives showed Cp to accumulate in the nucleus at early time points (~24 h), followed by a marked re-distribution to the cytoplasm at 48 to 72 h. Nucleus-associated Cp was confirmed to be capsid and/or high-order assemblages using a novel dual label immunofluorescence strategy. Nuclear-to-cytoplasmic re-localization of Cp occurred predominantly during nuclear envelope breakdown in conjunction with cell division, followed by strong cytoplasmic retention of Cp. Blocking cell division resulted in strong nuclear entrapment of high-order assemblages. A Cp mutant, Cp-V124W, predicted to exhibit enhanced assembly kinetics, also first trafficked to the nucleus to accumulate at nucleoli, consistent with the hypothesis that Cp's transit to the nucleus is a strong and constitutive process. Taken together, these results provide support for the nucleus as an early-stage site of HBV capsid assembly, and provide the first dynamic evidence of cytoplasmic retention after cell division as a mechanism underpinning capsid nucleus-to-cytoplasm relocalization. IMPORTANCE Hepatitis B virus (HBV) is an enveloped, reverse-transcribing DNA virus that is a major cause of liver disease and hepatocellular carcinoma. Subcellular trafficking events underpinning HBV capsid assembly and virion egress remain poorly characterized. Here, we developed a combination of fixed and long-term (>24 h) live cell imaging technologies to study the single cell trafficking dynamics of the HBV Core Protein (Cp). We demonstrate that Cp first accumulates in the nucleus, and forms high-order structures consistent with capsids, with the predominant route of nuclear egress being relocalization to the cytoplasm during cell division in conjunction with nuclear membrane breakdown. Single cell video microscopy demonstrated unequivocally that Cp's localization to the nucleus is constitutive. This study represents a pioneering application of live cell imaging to study HBV subcellular transport, and demonstrates links between HBV Cp and the cell cycle.
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Affiliation(s)
- Sofia Romero
- McArdle Laboratory for Cancer Research (Department of Oncology), University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Carbone Cancer Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Nuruddin Unchwaniwala
- McArdle Laboratory for Cancer Research (Department of Oncology), University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Carbone Cancer Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Edward L. Evans
- Laboratory for Optical and Computational Instrumentation, Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Morgridge Institute for Research, Madison, Wisconsin, USA
| | - Kevin W. Eliceiri
- Laboratory for Optical and Computational Instrumentation, Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Morgridge Institute for Research, Madison, Wisconsin, USA
| | - Daniel D. Loeb
- McArdle Laboratory for Cancer Research (Department of Oncology), University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
- Carbone Cancer Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Nathan M. Sherer
- McArdle Laboratory for Cancer Research (Department of Oncology), University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Carbone Cancer Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA
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7
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Zahoor MA, Kuipery A, Mosa AI, Gehring AJ, Feld JJ. HepG2-NTCP Subclones Exhibiting High Susceptibility to Hepatitis B Virus Infection. Viruses 2022; 14:v14081800. [PMID: 36016422 PMCID: PMC9412438 DOI: 10.3390/v14081800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/10/2022] [Accepted: 08/10/2022] [Indexed: 12/01/2022] Open
Abstract
HepG2 cells reconstituted with Hepatitis B virus (HBV) entry receptor sodium taurocholate co-transporting polypeptide (NTCP) are widely used as a convenient in vitro cell culture infection model for HBV replication studies. As such, it is pertinent that HBV infectivity is maintained at steady-state levels for an accurate interpretation of in vitro data. However, variations in the HBV infection efficiency due to imbalanced NTCP expression levels in the HepG2 cell line may affect experimental results. In this study, we performed single cell-cloning of HepG2-NTCP-A3 parental cells via limiting dilution and obtained multiple subclones with increased permissiveness to HBV. Specifically, one subclone (HepG2-NTCP-A3/C2) yielded more than four-fold higher HBV infection compared to the HepG2-NTCP-A3 parental clone. In addition, though HBV infectivity was universally reduced in the absence of polyethylene glycol (PEG), subclone C2 maintained relatively greater permissiveness under PEG-free conditions, suggesting the functional heterogeneity within parental HepG2-NTCP-A3 may be exploitable in developing a PEG-free HBV infection model. The increased viral production correlated with increased intracellular viral antigen expression as evidenced through HBcAg immunofluorescence staining. Further, these subclones were found to express different levels of NTCP, albeit with no remarkable morphology or cell growth differences. In conclusion, we isolated the subclones of HepG2-NTCP-A3 which support efficient HBV production and thus provide an improved in vitro HBV infection model.
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Affiliation(s)
- Muhammad Atif Zahoor
- Toronto Center for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada
| | - Adrian Kuipery
- Toronto Center for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada
- Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Alexander I. Mosa
- Toronto Center for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada
| | - Adam J. Gehring
- Toronto Center for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada
- Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Jordan J. Feld
- Toronto Center for Liver Disease, Toronto General Hospital Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada
- Correspondence:
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8
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Spunde K, Vigante B, Dubova UN, Sipola A, Timofejeva I, Zajakina A, Jansons J, Plotniece A, Pajuste K, Sobolev A, Muhamadejev R, Jaudzems K, Duburs G, Kozlovska T. Design and Synthesis of Hepatitis B Virus (HBV) Capsid Assembly Modulators and Evaluation of Their Activity in Mammalian Cell Model. Pharmaceuticals (Basel) 2022; 15:ph15070773. [PMID: 35890072 PMCID: PMC9317397 DOI: 10.3390/ph15070773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/15/2022] [Accepted: 06/17/2022] [Indexed: 12/02/2022] Open
Abstract
Capsid assembly modulators (CAMs) have emerged as a promising class of antiviral agents. We studied the effects of twenty-one newly designed and synthesized CAMs including heteroaryldihydropyrimidine compounds (HAPs), their analogs and standard compounds on hepatitis B virus (HBV) capsid assembly. Cytoplasmic expression of the HBV core (HBc) gene driven by the exogenously delivered recombinant alphavirus RNA replicon was used for high level production of the full-length HBc protein in mammalian cells. HBV capsid assembly was assessed by native agarose gel immunoblot analysis, electron microscopy and inhibition of virion secretion in HepG2.2.15 HBV producing cell line. Induced fit docking simulation was applied for modelling the structural relationships of the synthesized compounds and HBc. The most efficient were the HAP class compounds—dihydropyrimidine 5-carboxylic acid n-alkoxyalkyl esters, which induced the formation of incorrectly assembled capsid products and their accumulation within the cells. HBc product accumulation in the cells was not detected with the reference HAP compound Bay 41-4109, suggesting different modes of action. A significant antiviral effect and substantially reduced toxicity were revealed for two of the synthesized compounds. Two new HAP compounds revealed a significant antiviral effect and a favorable toxicity profile that allows these compounds to be considered promising leads and drug candidates for the treatment of HBV infection. The established alphavirus based HBc expression approach allows for the specific selection of capsid assembly modulators directly in the natural cell environment.
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Affiliation(s)
- Karina Spunde
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (U.N.D.); (I.T.); (A.Z.); (J.J.); (T.K.)
- Correspondence: (K.S.); (B.V.)
| | - Brigita Vigante
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia; (A.S.); (A.P.); (K.P.); (A.S.); (R.M.); (K.J.); (G.D.)
- Correspondence: (K.S.); (B.V.)
| | - Unda Nelda Dubova
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (U.N.D.); (I.T.); (A.Z.); (J.J.); (T.K.)
| | - Anda Sipola
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia; (A.S.); (A.P.); (K.P.); (A.S.); (R.M.); (K.J.); (G.D.)
| | - Irena Timofejeva
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (U.N.D.); (I.T.); (A.Z.); (J.J.); (T.K.)
| | - Anna Zajakina
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (U.N.D.); (I.T.); (A.Z.); (J.J.); (T.K.)
| | - Juris Jansons
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (U.N.D.); (I.T.); (A.Z.); (J.J.); (T.K.)
| | - Aiva Plotniece
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia; (A.S.); (A.P.); (K.P.); (A.S.); (R.M.); (K.J.); (G.D.)
| | - Karlis Pajuste
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia; (A.S.); (A.P.); (K.P.); (A.S.); (R.M.); (K.J.); (G.D.)
| | - Arkadij Sobolev
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia; (A.S.); (A.P.); (K.P.); (A.S.); (R.M.); (K.J.); (G.D.)
| | - Ruslan Muhamadejev
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia; (A.S.); (A.P.); (K.P.); (A.S.); (R.M.); (K.J.); (G.D.)
| | - Kristaps Jaudzems
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia; (A.S.); (A.P.); (K.P.); (A.S.); (R.M.); (K.J.); (G.D.)
| | - Gunars Duburs
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia; (A.S.); (A.P.); (K.P.); (A.S.); (R.M.); (K.J.); (G.D.)
| | - Tatjana Kozlovska
- Latvian Biomedical Research and Study Centre, LV-1067 Riga, Latvia; (U.N.D.); (I.T.); (A.Z.); (J.J.); (T.K.)
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Wang X, Wei Z, Cheng B, Li J, He Y, Lan T, Kemper T, Lin Y, Jiang B, Jiang Y, Meng Z, Lu M. Endoplasmic reticulum stress promotes HBV production by enhancing use of the autophagosome/multivesicular body axis. Hepatology 2022; 75:438-454. [PMID: 34580902 DOI: 10.1002/hep.32178] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 09/06/2021] [Accepted: 09/24/2021] [Indexed: 12/23/2022]
Abstract
BACKGROUND AND AIMS HBV infection has been reported to trigger endoplasmic reticulum (ER) stress and initiate autophagy. However, how ER stress and autophagy influence HBV production remains elusive. Here, we studied the effect of tunicamycin (TM), an N-glycosylation inhibitor and ER stress inducer, on HBV replication and secretion and examined the underlying mechanisms. APPROACH AND RESULTS Protein disulfide isomerase (an ER marker), microtubule-associated protein 1 light chain 3 beta (an autophagosome [AP] marker), and sequestosome-1 (a typical cargo for autophagic degradation) expression were tested in liver tissues of patients with chronic HBV infection and hepatoma cell lines. The role of TM treatment in HBV production and trafficking was examined in hepatoma cell lines. TM treatment that mimics HBV infection triggered ER stress and increased AP formation, resulting in enhanced HBV replication and secretion of subviral particles (SVPs) and naked capsids. Additionally, TM reduced the number of early endosomes and HBsAg localization in this compartment, causing HBsAg/SVPs to accumulate in the ER. Thus, TM-induced AP formation serves as an alternative pathway for HBsAg/SVP trafficking. Importantly, TM inhibited AP-lysosome fusion, accompanied by enhanced AP/late endosome (LE)/multivesicular body fusion, to release HBsAg/SVPs through, or along with, exosome release. Notably, TM treatment inhibited HBsAg glycosylation, resulting in impairment of HBV virions' envelopment and secretion, but it was not critical for HBsAg/SVP trafficking in our cell systems. CONCLUSIONS TM-induced ER stress and autophagic flux promoted HBV replication and the release of SVPs and naked capsids through the AP-LE/MVB axis.
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Affiliation(s)
- Xueyu Wang
- Department of Infectious DiseasesThe Second Xiangya HospitalCentral South UniversityChangshaHunan ProvinceChina.,Institute of VirologyUniversity Hospital EssenUniversity of Duisburg-EssenEssenGermany
| | - Zhiqiang Wei
- Institute of VirologyUniversity Hospital EssenUniversity of Duisburg-EssenEssenGermany.,Institute of Biomedical ResearchHubei Clinical Research Center for Precise Diagnosis and Treatment of Liver CancerTaihe HospitalHubei University of MedicineShiyanChina
| | - Bin Cheng
- Institute of Biomedical ResearchHubei Clinical Research Center for Precise Diagnosis and Treatment of Liver CancerTaihe HospitalHubei University of MedicineShiyanChina
| | - Jia Li
- Institute of VirologyUniversity Hospital EssenUniversity of Duisburg-EssenEssenGermany
| | - Yulin He
- Institute of Biomedical ResearchHubei Clinical Research Center for Precise Diagnosis and Treatment of Liver CancerTaihe HospitalHubei University of MedicineShiyanChina
| | - Tingyu Lan
- Institute of Biomedical ResearchHubei Clinical Research Center for Precise Diagnosis and Treatment of Liver CancerTaihe HospitalHubei University of MedicineShiyanChina
| | - Thekla Kemper
- Institute of VirologyUniversity Hospital EssenUniversity of Duisburg-EssenEssenGermany
| | - Yong Lin
- The Key Laboratory of Molecular Biology of Infectious Diseases designated by the Chinese Ministry of EducationChongqing Medical UniversityChongqingChina
| | - Bin Jiang
- Institute of Biomedical ResearchHubei Clinical Research Center for Precise Diagnosis and Treatment of Liver CancerTaihe HospitalHubei University of MedicineShiyanChina.,Department of Hepatobiliary Pancreatic SurgeryTaihe HospitalHubei University of MedicineShiyanChina
| | - Yongfang Jiang
- Department of Infectious DiseasesThe Second Xiangya HospitalCentral South UniversityChangshaHunan ProvinceChina
| | - Zhongji Meng
- Institute of Biomedical ResearchHubei Clinical Research Center for Precise Diagnosis and Treatment of Liver CancerTaihe HospitalHubei University of MedicineShiyanChina.,Department of Infectious DiseasesTaihe HospitalHubei University of MedicineShiyanChina
| | - Mengji Lu
- Institute of VirologyUniversity Hospital EssenUniversity of Duisburg-EssenEssenGermany
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10
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Wang C, Zhai N, Zhao Y, Wu F, Luo X, Ju X, Liu G, Liu H. Exploration of Novel Hepatitis B Virus Capsid Assembly Modulators by Integrated Molecular Simulations. ChemistrySelect 2021. [DOI: 10.1002/slct.202102965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Chenchen Wang
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology Key Laboratory for Green Chemical Process of Ministry of Education School of Chemical Engineering and Pharmacy Wuhan Institute of Technology Wuhan 430205 Hubei P. R. China
| | - Na Zhai
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology Key Laboratory for Green Chemical Process of Ministry of Education School of Chemical Engineering and Pharmacy Wuhan Institute of Technology Wuhan 430205 Hubei P. R. China
| | - Yilan Zhao
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology Key Laboratory for Green Chemical Process of Ministry of Education School of Chemical Engineering and Pharmacy Wuhan Institute of Technology Wuhan 430205 Hubei P. R. China
| | - Fengshou Wu
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology Key Laboratory for Green Chemical Process of Ministry of Education School of Chemical Engineering and Pharmacy Wuhan Institute of Technology Wuhan 430205 Hubei P. R. China
| | - Xiaogang Luo
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology Key Laboratory for Green Chemical Process of Ministry of Education School of Chemical Engineering and Pharmacy Wuhan Institute of Technology Wuhan 430205 Hubei P. R. China
- School of Materials Science and Engineering Zhengzhou University No.100 Science Avenue Zhengzhou 450001 Henan P. R. China
| | - Xiulian Ju
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology Key Laboratory for Green Chemical Process of Ministry of Education School of Chemical Engineering and Pharmacy Wuhan Institute of Technology Wuhan 430205 Hubei P. R. China
| | - Genyan Liu
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology Key Laboratory for Green Chemical Process of Ministry of Education School of Chemical Engineering and Pharmacy Wuhan Institute of Technology Wuhan 430205 Hubei P. R. China
| | - Hui Liu
- Department of Hematology Renmin Hospital of Wuhan University Wuhan 430060 Hubei P. R. China
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11
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Niklasch M, Zimmermann P, Nassal M. The Hepatitis B Virus Nucleocapsid-Dynamic Compartment for Infectious Virus Production and New Antiviral Target. Biomedicines 2021; 9:1577. [PMID: 34829806 PMCID: PMC8615760 DOI: 10.3390/biomedicines9111577] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/19/2021] [Accepted: 10/21/2021] [Indexed: 12/11/2022] Open
Abstract
Hepatitis B virus (HBV) is a small enveloped DNA virus which replicates its tiny 3.2 kb genome by reverse transcription inside an icosahedral nucleocapsid, formed by a single ~180 amino acid capsid, or core, protein (Cp). HBV causes chronic hepatitis B (CHB), a severe liver disease responsible for nearly a million deaths each year. Most of HBV's only seven primary gene products are multifunctional. Though less obvious than for the multi-domain polymerase, P protein, this is equally crucial for Cp with its multiple roles in the viral life-cycle. Cp provides a stable genome container during extracellular phases, allows for directed intracellular genome transport and timely release from the capsid, and subsequent assembly of new nucleocapsids around P protein and the pregenomic (pg) RNA, forming a distinct compartment for reverse transcription. These opposing features are enabled by dynamic post-transcriptional modifications of Cp which result in dynamic structural alterations. Their perturbation by capsid assembly modulators (CAMs) is a promising new antiviral concept. CAMs inappropriately accelerate assembly and/or distort the capsid shell. We summarize the functional, biochemical, and structural dynamics of Cp, and discuss the therapeutic potential of CAMs based on clinical data. Presently, CAMs appear as a valuable addition but not a substitute for existing therapies. However, as part of rational combination therapies CAMs may bring the ambitious goal of a cure for CHB closer to reality.
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Affiliation(s)
| | | | - Michael Nassal
- Internal Medicine II/Molecular Biology, University Hospital Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany; (M.N.); (P.Z.)
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12
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Wei L, Ploss A. Mechanism of Hepatitis B Virus cccDNA Formation. Viruses 2021; 13:v13081463. [PMID: 34452329 PMCID: PMC8402782 DOI: 10.3390/v13081463] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/14/2021] [Accepted: 07/21/2021] [Indexed: 02/06/2023] Open
Abstract
Hepatitis B virus (HBV) remains a major medical problem affecting at least 257 million chronically infected patients who are at risk of developing serious, frequently fatal liver diseases. HBV is a small, partially double-stranded DNA virus that goes through an intricate replication cycle in its native cellular environment: human hepatocytes. A critical step in the viral life-cycle is the conversion of relaxed circular DNA (rcDNA) into covalently closed circular DNA (cccDNA), the latter being the major template for HBV gene transcription. For this conversion, HBV relies on multiple host factors, as enzymes capable of catalyzing the relevant reactions are not encoded in the viral genome. Combinations of genetic and biochemical approaches have produced findings that provide a more holistic picture of the complex mechanism of HBV cccDNA formation. Here, we review some of these studies that have helped to provide a comprehensive picture of rcDNA to cccDNA conversion. Mechanistic insights into this critical step for HBV persistence hold the key for devising new therapies that will lead not only to viral suppression but to a cure.
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13
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Sajidah ES, Lim K, Wong RW. How SARS-CoV-2 and Other Viruses Build an Invasion Route to Hijack the Host Nucleocytoplasmic Trafficking System. Cells 2021; 10:1424. [PMID: 34200500 PMCID: PMC8230057 DOI: 10.3390/cells10061424] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 05/31/2021] [Accepted: 06/03/2021] [Indexed: 12/14/2022] Open
Abstract
The host nucleocytoplasmic trafficking system is often hijacked by viruses to accomplish their replication and to suppress the host immune response. Viruses encode many factors that interact with the host nuclear transport receptors (NTRs) and the nucleoporins of the nuclear pore complex (NPC) to access the host nucleus. In this review, we discuss the viral factors and the host factors involved in the nuclear import and export of viral components. As nucleocytoplasmic shuttling is vital for the replication of many viruses, we also review several drugs that target the host nuclear transport machinery and discuss their feasibility for use in antiviral treatment.
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Affiliation(s)
- Elma Sakinatus Sajidah
- Division of Nano Life Science in the Graduate School of Frontier Science Initiative, Kanazawa University, Kanazawa 920-1192, Japan;
| | - Keesiang Lim
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa 920-1192, Japan
| | - Richard W. Wong
- Division of Nano Life Science in the Graduate School of Frontier Science Initiative, Kanazawa University, Kanazawa 920-1192, Japan;
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa 920-1192, Japan
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa 920-1192, Japan
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14
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Regulation of Hepatitis B Virus Replication by Cyclin Docking Motifs in Core Protein. J Virol 2021; 95:JVI.00230-21. [PMID: 33789995 DOI: 10.1128/jvi.00230-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 03/27/2021] [Indexed: 12/16/2022] Open
Abstract
Hepatitis B virus (HBV) capsid or core protein (HBc) consists of an N-terminal domain (NTD) and a C-terminal domain (CTD) connected by a short linker peptide. Dynamic phosphorylation and dephosphorylation of HBc regulate its multiple functions in capsid assembly and viral replication. The cellular cyclin-dependent kinase 2 (CDK2) plays a major role in HBc phosphorylation and, furthermore, is incorporated into the viral capsid, accounting for most of the "endogenous kinase" activity associated with the capsid. The packaged CDK2 is thought to play a role in phosphorylating HBc to trigger nucleocapsid disassembly (uncoating), an essential step during viral infection. However, little is currently known on how CDK2 is recruited and packaged into the capsid. We have now identified three RXL motifs in the HBc NTD known as cyclin docking motifs (CDMs), which mediate the interactions of various CDK substrates/regulators with CDK/cyclin complexes. Mutations of the CDMs in the HBc NTD reduced CTD phosphorylation and diminished CDK2 packaging into the capsid. Also, the CDM mutations showed little effects on capsid assembly and pregenomic RNA (pgRNA) packaging but impaired the integrity of mature nucleocapsids. Furthermore, the CDM mutations blocked covalently closed circular DNA (CCC DNA) formation during infection while having no effect on or enhancing CCC DNA formation via intracellular amplification. These results indicate that the HBc NTD CDMs play a role in CDK2 recruitment and packaging, which, in turn, is important for productive infection.IMPORTANCE Hepatitis B virus (HBV) is an important global human pathogen and persistently infects hundreds of millions of people, who are at high risk of cirrhosis and liver cancer. HBV capsid packages a host cell protein kinase, the cyclin-dependent kinase 2 (CDK2), which is thought to be required to trigger disassembly of the viral nucleocapsid during infection by phosphorylating the capsid protein, a prerequisite for successful infection. We have identified docking sites on the capsid protein for recruiting CDK2, in complex with its cyclin partner, to facilitate capsid protein phosphorylation and CDK2 packaging. Mutations of these docking sites reduced capsid protein phosphorylation, impaired CDK2 packaging into HBV capsids, and blocked HBV infection. These results provide novel insights regarding CDK2 packaging into HBV capsids and the role of CDK2 in HBV infection and should facilitate the development of antiviral drugs that target the HBV capsid protein.
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