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Pastor F, Charles E, Belmudes L, Chabrolles H, Cescato M, Rivoire M, Burger T, Passot G, Durantel D, Lucifora J, Couté Y, Salvetti A. Deciphering the phospho-signature induced by hepatitis B virus in primary human hepatocytes. Front Microbiol 2024; 15:1415449. [PMID: 38841065 PMCID: PMC11150682 DOI: 10.3389/fmicb.2024.1415449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 05/02/2024] [Indexed: 06/07/2024] Open
Abstract
Phosphorylation is a major post-translation modification (PTM) of proteins which is finely tuned by the activity of several hundred kinases and phosphatases. It controls most if not all cellular pathways including anti-viral responses. Accordingly, viruses often induce important changes in the phosphorylation of host factors that can either promote or counteract viral replication. Among more than 500 kinases constituting the human kinome only few have been described as important for the hepatitis B virus (HBV) infectious cycle, and most of them intervene during early or late infectious steps by phosphorylating the viral Core (HBc) protein. In addition, little is known on the consequences of HBV infection on the activity of cellular kinases. The objective of this study was to investigate the global impact of HBV infection on the cellular phosphorylation landscape early after infection. For this, primary human hepatocytes (PHHs) were challenged or not with HBV, and a mass spectrometry (MS)-based quantitative phosphoproteomic analysis was conducted 2- and 7-days post-infection. The results indicated that while, as expected, HBV infection only minimally modified the cell proteome, significant changes were observed in the phosphorylation state of several host proteins at both time points. Gene enrichment and ontology analyses of up- and down-phosphorylated proteins revealed common and distinct signatures induced by infection. In particular, HBV infection resulted in up-phosphorylation of proteins involved in DNA damage signaling and repair, RNA metabolism, in particular splicing, and cytoplasmic cell-signaling. Down-phosphorylated proteins were mostly involved in cell signaling and communication. Validation studies carried out on selected up-phosphorylated proteins, revealed that HBV infection induced a DNA damage response characterized by the appearance of 53BP1 foci, the inactivation of which by siRNA increased cccDNA levels. In addition, among up-phosphorylated RNA binding proteins (RBPs), SRRM2, a major scaffold of nuclear speckles behaved as an antiviral factor. In accordance with these findings, kinase prediction analysis indicated that HBV infection upregulates the activity of major kinases involved in DNA repair. These results strongly suggest that HBV infection triggers an intrinsic anti-viral response involving DNA repair factors and RBPs that contribute to reduce HBV replication in cell culture models.
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Affiliation(s)
- Florentin Pastor
- International Center for Research in Infectiology (CIRI), INSERM U1111, Université Claude Bernard Lyon, CNRS, UMR5308, ENS, Lyon, France
| | - Emilie Charles
- International Center for Research in Infectiology (CIRI), INSERM U1111, Université Claude Bernard Lyon, CNRS, UMR5308, ENS, Lyon, France
| | - Lucid Belmudes
- Université Grenoble Alpes, CEA, INSERM, UA13 BGE, CEA, CNRS, FR2048, Grenoble, France
| | - Hélène Chabrolles
- International Center for Research in Infectiology (CIRI), INSERM U1111, Université Claude Bernard Lyon, CNRS, UMR5308, ENS, Lyon, France
| | - Marion Cescato
- International Center for Research in Infectiology (CIRI), INSERM U1111, Université Claude Bernard Lyon, CNRS, UMR5308, ENS, Lyon, France
| | | | - Thomas Burger
- Université Grenoble Alpes, CEA, INSERM, UA13 BGE, CEA, CNRS, FR2048, Grenoble, France
| | - Guillaume Passot
- Service de Chirurgie Générale et Oncologique, Hôpital Lyon Sud, Hospices Civils de Lyon Et CICLY, EA3738, Université Claude Bernard Lyon, Lyon, France
| | - David Durantel
- International Center for Research in Infectiology (CIRI), INSERM U1111, Université Claude Bernard Lyon, CNRS, UMR5308, ENS, Lyon, France
| | - Julie Lucifora
- International Center for Research in Infectiology (CIRI), INSERM U1111, Université Claude Bernard Lyon, CNRS, UMR5308, ENS, Lyon, France
| | - Yohann Couté
- Université Grenoble Alpes, CEA, INSERM, UA13 BGE, CEA, CNRS, FR2048, Grenoble, France
| | - Anna Salvetti
- International Center for Research in Infectiology (CIRI), INSERM U1111, Université Claude Bernard Lyon, CNRS, UMR5308, ENS, Lyon, France
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2
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Yip RPH, Kwok DCY, Lai LTF, Ho SM, Wong ICK, Chan CP, Lau WCY, Ngo JCK. SRPK2 Mediates HBV Core Protein Phosphorylation and Capsid Assembly via Docking Interaction. PLoS Pathog 2024; 20:e1011978. [PMID: 38324561 PMCID: PMC10878513 DOI: 10.1371/journal.ppat.1011978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 02/20/2024] [Accepted: 01/17/2024] [Indexed: 02/09/2024] Open
Abstract
Members of the serine-arginine protein kinase (SRPK) family, SRPK1 and SRPK2, phosphorylate the hepatitis B core protein (Cp) and are crucial for pregenomic RNA encapsidation during viral nucleocapsid assembly. Among them, SRPK2 exhibits higher kinase activity toward Cp. In this study, we identified Cp sites that are phosphorylated by SRPK2 and demonstrated that the kinase utilizes an SRPK-specific docking groove to interact with and regulate the phosphorylation of the C-terminal arginine rich domain of Cp. We determined that direct interaction between the docking groove of SRPK2 and unphosphorylated Cp inhibited premature viral capsid assembly in vitro, whereas the phosphorylation of the viral protein reactivated the process. Pull-down assays together with the new cryo-electron microscopy structure of the HBV capsid in complex with SRPK2 revealed that the kinases decorate the surface of the viral capsid by interacting with the C-terminal domain of Cp, underscoring the importance of the docking interaction in regulating capsid assembly and pregenome packaging. Moreover, SRPK2-knockout in HepG2 cells suppressed Cp phosphorylation, indicating that SRPK2 is an important cellular kinase for HBV life cycle.
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Affiliation(s)
- Ryan Pak Hong Yip
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Doris Ching Ying Kwok
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Louis Tung Faat Lai
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Siu-Ming Ho
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong, Hong Kong SAR, China
- State Key Laboratory of Liver Research (The University of Hong Kong), Pokfulam, Hong Kong, Hong Kong SAR, China
| | - Ivan Chun Kit Wong
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Chi-Ping Chan
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong, Hong Kong SAR, China
- State Key Laboratory of Liver Research (The University of Hong Kong), Pokfulam, Hong Kong, Hong Kong SAR, China
| | - Wilson Chun Yu Lau
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin N.T., Hong Kong SAR, China
| | - Jacky Chi Ki Ngo
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin N.T., Hong Kong SAR, China
- Center for Novel Biomaterials, The Chinese University of Hong Kong, Shatin N.T., Hong Kong SAR, China
- Center for Protein Science and Crystallography, The Chinese University of Hong Kong, Shatin N.T., Hong Kong SAR, China
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3
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Yang R, Ko YH, Li F, Lokareddy RK, Hou CFD, Kim C, Klein S, Antolínez S, Marín JF, Pérez-Segura C, Jarrold MF, Zlotnick A, Hadden-Perilla JA, Cingolani G. Structural basis for nuclear import of hepatitis B virus (HBV) nucleocapsid core. SCIENCE ADVANCES 2024; 10:eadi7606. [PMID: 38198557 PMCID: PMC10780889 DOI: 10.1126/sciadv.adi7606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 12/08/2023] [Indexed: 01/12/2024]
Abstract
Nuclear import of the hepatitis B virus (HBV) nucleocapsid is essential for replication that occurs in the nucleus. The ~360-angstrom HBV capsid translocates to the nuclear pore complex (NPC) as an intact particle, hijacking human importins in a reaction stimulated by host kinases. This paper describes the mechanisms of HBV capsid recognition by importins. We found that importin α1 binds a nuclear localization signal (NLS) at the far end of the HBV coat protein Cp183 carboxyl-terminal domain (CTD). This NLS is exposed to the capsid surface through a pore at the icosahedral quasi-sixfold vertex. Phosphorylation at serine-155, serine-162, and serine-170 promotes CTD compaction but does not affect the affinity for importin α1. The binding of 30 importin α1/β1 augments HBV capsid diameter to ~620 angstroms, close to the maximum size trafficable through the NPC. We propose that phosphorylation favors CTD externalization and prompts its compaction at the capsid surface, exposing the NLS to importins.
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Affiliation(s)
- Ruoyu Yang
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Ying-Hui Ko
- Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, 1825 University Blvd, Birmingham, AL 35294, USA
| | - Fenglin Li
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Ravi K. Lokareddy
- Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, 1825 University Blvd, Birmingham, AL 35294, USA
| | - Chun-Feng David Hou
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Christine Kim
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, IN 47405, USA
| | - Shelby Klein
- Department of Chemistry, Indiana University, Bloomington, Indiana, IN 47405, USA
| | - Santiago Antolínez
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Juan F. Marín
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Carolina Pérez-Segura
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Martin F. Jarrold
- Department of Chemistry, Indiana University, Bloomington, Indiana, IN 47405, USA
| | - Adam Zlotnick
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, IN 47405, USA
| | | | - Gino Cingolani
- Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, 1825 University Blvd, Birmingham, AL 35294, USA
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4
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Li X, Nakashima K, Ito M, Matsuda M, Chida T, Sekihara K, Takahashi H, Kato T, Sawasaki T, Suzuki T. SRPKIN-1 as an inhibitor against hepatitis B virus blocking the viral particle formation and the early step of the viral infection. Antiviral Res 2023; 220:105756. [PMID: 37992764 DOI: 10.1016/j.antiviral.2023.105756] [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: 04/24/2023] [Revised: 11/13/2023] [Accepted: 11/13/2023] [Indexed: 11/24/2023]
Abstract
New antiviral agents are needed for the treatment of hepatitis B virus (HBV) infection because currently available drugs do not completely eradicate chronic HBV in patients. Phosphorylation dynamics of the HBV core protein (HBc) regulate several processes in the HBV life cycle, including nucleocapsid formation, cell trafficking, and virus uncoating after entry. In this study, the SRPK inhibitors SPHINX31, SRPIN340, and SRPKIN-1 showed concentration-dependent anti-HBV activity. Detailed analysis of the effects of SRPKIN-1, which exhibited the strongest inhibitory activity, on the HBV replication process showed that it inhibits the formation of infectious particles by inhibiting pregenomic RNA packaging into capsids and nucleocapsid envelopment. Mass spectrometry analysis combined with cell-free translation system experiments revealed that hyperphosphorylation of the C-terminal domain of HBc is inhibited by SRPKIN-1. Further, SRPKIN-1 exhibited concentration-dependent inhibition of HBV infection not only in HepG2-hNTCP-C4 cells but also in fresh human hepatocytes (PXB cells) and in the single-round infection system. Treatment with SRPKIN-1 at the time of infection reduced the nuclease sensitivity of HBV DNA in the nuclear fraction. These results suggest that SRPKIN-1 has the potential to not only inhibit the HBV particle formation process but also impair the early stages of viral infection.
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Affiliation(s)
- Xiaofang Li
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Kenji Nakashima
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Masahiko Ito
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Mami Matsuda
- Department of Virology II, National Institute of Infectious Diseases, Musashi-murayama, Japan
| | - Takeshi Chida
- Department of Internal Medicine II, Hamamatsu University School of Medicine, Shizuoka, Japan; Department of Regional Medical Care Support, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Kazumasa Sekihara
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Hirotaka Takahashi
- Division of Cell-Free Science, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Takanobu Kato
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tatsuya Sawasaki
- Division of Cell-Free Science, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Tetsuro Suzuki
- Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Shizuoka, Japan.
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5
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Saeed U, Piracha ZZ, Alrokayan S, Hussain T, Almajhdi FN, Waheed Y. Immunoinformatics and Evaluation of Peptide Vaccines Derived from Global Hepatitis B Viral HBx and HBc Proteins Critical for Covalently Closed Circular DNA Integrity. Microorganisms 2023; 11:2826. [PMID: 38137971 PMCID: PMC10745757 DOI: 10.3390/microorganisms11122826] [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: 10/18/2023] [Revised: 11/07/2023] [Accepted: 11/17/2023] [Indexed: 12/24/2023] Open
Abstract
The Hepatitis B virus (HBV) HBx and HBc proteins play a crucial role in associating with covalently closed circular DNA (cccDNA), the primary factor contributing to intrahepatic viral persistence and a major obstacle in achieving a cure for HBV. The cccDNA serves as a reservoir for viral persistence. Targeting the viral HBc and HBx proteins' interaction with cccDNA could potentially limit HBV replication. In this study, we present epitopes identified from global consensus sequences of HBx and HBc proteins that have the potential to serve as targets for the development of effective vaccine candidates. Furthermore, conserved residues identified through this analysis can be utilized in designing novel, site-specific anti-HBV agents capable of targeting all major genotypes of HBV. Our approach involved designing global consensus sequences for HBx and HBc proteins, enabling the analysis of variable regions and highly conserved motifs. These identified motifs and regions offer potent sites for the development of peptide vaccines, the design of site-specific RNA interference, and the creation of anti-HBV inhibitors. The epitopes derived from global consensus sequences of HBx and HBc proteins emerge as promising targets for the development of effective vaccine candidates. Additionally, the conserved residues identified provide valuable insights for the development of innovative, site-specific anti-HBV agents capable of targeting all major genotypes of HBV from A to J.
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Affiliation(s)
- Umar Saeed
- Clinical and Biomedical Research Center (CBRC) and Multidisciplinary Laboratory (MDL), Foundation University Islamabad, Islamabad 44000, Pakistan;
- Department of Microbiology, Ajou University School of Medicine, Suwon 443-749, Republic of Korea;
| | - Zahra Zahid Piracha
- Department of Microbiology, Ajou University School of Medicine, Suwon 443-749, Republic of Korea;
- International Center of Medical Sciences Research (ICMSR), Islamabad 44000, Pakistan
| | - Salman Alrokayan
- Research Chair for Biomedical Application of Nanomaterials, Biochemistry Department, College of Sciences, King Saud University, Riyadh 11362, Saudi Arabia;
| | - Tajamul Hussain
- Research Chair for Biomedical Application of Nanomaterials, Biochemistry Department, College of Sciences, King Saud University, Riyadh 11362, Saudi Arabia;
- Center of Excellence in Biotechnology Research, College of Applied Medical Sciences, King Saud University, P.O. Box 10219, Riyadh 11451, Saudi Arabia
| | - Fahad N. Almajhdi
- Botany and Microbiology Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia;
| | - Yasir Waheed
- Office of Research, Innovation, and Commercialization, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad 44000, Pakistan;
- Gilbert and Rose-Marie Chagoury School of Medicine, Lebanese American University, Byblos 1401, Lebanon
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6
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Pluta AJ, Studniarek C, Murphy S, Norbury CJ. Cyclin-dependent kinases: Masters of the eukaryotic universe. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 15:e1816. [PMID: 37718413 PMCID: PMC10909489 DOI: 10.1002/wrna.1816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 07/21/2023] [Accepted: 08/03/2023] [Indexed: 09/19/2023]
Abstract
A family of structurally related cyclin-dependent protein kinases (CDKs) drives many aspects of eukaryotic cell function. Much of the literature in this area has considered individual members of this family to act primarily either as regulators of the cell cycle, the context in which CDKs were first discovered, or as regulators of transcription. Until recently, CDK7 was the only clear example of a CDK that functions in both processes. However, new data points to several "cell-cycle" CDKs having important roles in transcription and some "transcriptional" CDKs having cell cycle-related targets. For example, novel functions in transcription have been demonstrated for the archetypal cell cycle regulator CDK1. The increasing evidence of the overlap between these two CDK types suggests that they might play a critical role in coordinating the two processes. Here we review the canonical functions of cell-cycle and transcriptional CDKs, and provide an update on how these kinases collaborate to perform important cellular functions. We also provide a brief overview of how dysregulation of CDKs contributes to carcinogenesis, and possible treatment avenues. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Processing > 3' End Processing RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
| | | | - Shona Murphy
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
| | - Chris J. Norbury
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
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7
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Kim C, Schlicksup CJ, Pérez-Segura C, Hadden-Perilla JA, Wang JCY, Zlotnick A. Structure of the Hepatitis B virus capsid quasi-6-fold with a trapped C-terminal domain reveals capsid movements associated with domain exit. J Biol Chem 2023; 299:105104. [PMID: 37517693 PMCID: PMC10463254 DOI: 10.1016/j.jbc.2023.105104] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 07/08/2023] [Accepted: 07/11/2023] [Indexed: 08/01/2023] Open
Abstract
Many viruses undergo transient conformational change to surveil their environments for receptors and host factors. In Hepatitis B virus (HBV) infection, after the virus enters the cell, it is transported to the nucleus by interaction of the HBV capsid with an importin α/β complex. The interaction between virus and importins is mediated by nuclear localization signals on the capsid protein's C-terminal domain (CTD). However, CTDs are located inside the capsid. In this study, we asked where does a CTD exit the capsid, are all quasi-equivalent CTDs created equal, and does the capsid structure deform to facilitate CTD egress from the capsid? Here, we used Impβ as a tool to trap transiently exposed CTDs and examined this complex by cryo-electron microscopy. We examined an asymmetric reconstruction of a T = 4 icosahedral capsid and a focused reconstruction of a quasi-6-fold vertex (3.8 and 4.0 Å resolution, respectively). Both approaches showed that a subset of CTDs extended through a pore in the center of the quasi-6-fold complex. CTD egress was accompanied by enlargement of the pore and subtle changes in quaternary and tertiary structure of the quasi-6-fold. When compared to molecular dynamics simulations, structural changes were within the normal range of capsid flexibility. Although pore diameter was enlarged in the Impβ-bound reconstruction, simulations indicate that CTD egress does not exclusively depend on enlarged pores. In summary, we find that HBV surveillance of its environment by transient exposure of its CTD requires only modest conformational change of the capsid.
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Affiliation(s)
- Christine Kim
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana, USA
| | | | - Carolina Pérez-Segura
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA
| | - Jodi A Hadden-Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA
| | - Joseph Che-Yen Wang
- Department of Microbiology & Immunology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Adam Zlotnick
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana, USA.
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8
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Kwon H, Kim J, Song C, Sajjad MA, Ha J, Jung J, Park S, Shin HJ, Kim K. Peptidyl-prolyl cis/trans isomerase Pin1 interacts with hepatitis B virus core particle, but not with HBc protein, to promote HBV replication. Front Cell Infect Microbiol 2023; 13:1195063. [PMID: 37404723 PMCID: PMC10315659 DOI: 10.3389/fcimb.2023.1195063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 06/01/2023] [Indexed: 07/06/2023] Open
Abstract
Here, we demonstrate that the peptidyl-prolyl cis/trans isomerase Pin1 interacts noncovalently with the hepatitis B virus (HBV) core particle through phosphorylated serine/threonine-proline (pS/TP) motifs in the carboxyl-terminal domain (CTD) but not with particle-defective, dimer-positive mutants of HBc. This suggests that neither dimers nor monomers of HBc are Pin1-binding partners. The 162TP, 164SP, and 172SP motifs within the HBc CTD are important for the Pin1/core particle interaction. Although Pin1 dissociated from core particle upon heat treatment, it was detected as an opened-up core particle, demonstrating that Pin1 binds both to the outside and the inside of the core particle. Although the amino-terminal domain S/TP motifs of HBc are not involved in the interaction, 49SP contributes to core particle stability, and 128TP might be involved in core particle assembly, as shown by the decreased core particle level of S49A mutant through repeated freeze and thaw and low-level assembly of the T128A mutant, respectively. Overexpression of Pin1 increased core particle stability through their interactions, HBV DNA synthesis, and virion secretion without concomitant increases in HBV RNA levels, indicating that Pin1 may be involved in core particle assembly and maturation, thereby promoting the later stages of the HBV life cycle. By contrast, parvulin inhibitors and PIN1 knockdown reduced HBV replication. Since more Pin1 proteins bound to immature core particles than to mature core particles, the interaction appears to depend on the stage of virus replication. Taken together, the data suggest that physical association between Pin1 and phosphorylated core particles may induce structural alterations through isomerization by Pin1, induce dephosphorylation by unidentified host phosphatases, and promote completion of virus life cycle.
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Affiliation(s)
- Hyeonjoong Kwon
- Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea
| | - Jumi Kim
- Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea
| | - Chanho Song
- Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea
| | - Muhammad Azhar Sajjad
- Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea
| | - Jiseon Ha
- Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea
| | - Jaesung Jung
- Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea
| | - Sun Park
- Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea
| | - Ho-Joon Shin
- Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea
| | - Kyongmin Kim
- Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea
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9
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Hofmann S, Plank V, Groitl P, Skvorc N, Hofmann K, Luther J, Ko C, Zimmerman P, Bruss V, Stadler D, Carpentier A, Rezk S, Nassal M, Protzer U, Schreiner S. SUMO Modification of Hepatitis B Virus Core Mediates Nuclear Entry, Promyelocytic Leukemia Nuclear Body Association, and Efficient Formation of Covalently Closed Circular DNA. Microbiol Spectr 2023; 11:e0044623. [PMID: 37199632 PMCID: PMC10269885 DOI: 10.1128/spectrum.00446-23] [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: 02/05/2023] [Accepted: 04/24/2023] [Indexed: 05/19/2023] Open
Abstract
Persistence of hepatitis B virus (HBV) infection is due to a nuclear covalently closed circular DNA (cccDNA), generated from the virion-borne relaxed circular DNA (rcDNA) genome in a process likely involving numerous cell factors from the host DNA damage response (DDR). The HBV core protein mediates rcDNA transport to the nucleus and likely affects stability and transcriptional activity of cccDNA. Our study aimed at investigating the role of HBV core protein and its posttranslational modification (PTM) with SUMO (small ubiquitin-like modifiers) during the establishment of cccDNA. HBV core protein SUMO PTM was analyzed in His-SUMO-overexpressing cell lines. The impact of HBV core SUMOylation on association with cellular interaction partners and on the HBV life cycle was determined using SUMOylation-deficient mutants of the HBV core protein. Here, we show that the HBV core protein is posttranslationally modified by the addition of SUMO and that this modification impacts nuclear import of rcDNA. By using SUMOylation-deficient HBV core mutants, we show that SUMO modification is a prerequisite for the association with specific promyelocytic leukemia nuclear bodies (PML-NBs) and regulates the conversion of rcDNA to cccDNA. By in vitro SUMOylation of HBV core, we obtained evidence that SUMOylation triggers nucleocapsid disassembly, providing novel insights into the nuclear import process of rcDNA. HBV core protein SUMOylation and subsequent association with PML bodies in the nucleus constitute a key step in the conversion of HBV rcDNA to cccDNA and therefore a promising target for inhibiting formation of the HBV persistence reservoir. IMPORTANCE HBV cccDNA is formed from the incomplete rcDNA involving several host DDR proteins. The exact process and the site of cccDNA formation are poorly understood. Here, we show that HBV core protein SUMO modification is a novel PTM regulating the function of HBV core. A minor specific fraction of the HBV core protein resides with PML-NBs in the nuclear matrix. SUMO modification of HBV core protein mediates its recruitment to specific PML-NBs within the host cell. Within HBV nucleocapsids, SUMOylation of HBV core induces HBV capsid disassembly and is a prerequisite for nuclear entry of HBV core. SUMO HBV core protein association with PML-NBs is crucial for efficient conversion of rcDNA to cccDNA and for the establishment of the viral persistence reservoir. HBV core protein SUMO modification and the subsequent association with PML-NBs might constitute a potential novel target in the development of drugs targeting the cccDNA.
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Affiliation(s)
- Samuel Hofmann
- Institute of Virology, School of Medicine, Technical University of Munich, Germany
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Verena Plank
- Institute of Virology, School of Medicine, Technical University of Munich, Germany
| | - Peter Groitl
- Institute of Virology, School of Medicine, Technical University of Munich, Germany
| | - Nathalie Skvorc
- Institute of Virology, School of Medicine, Technical University of Munich, Germany
| | - Katharina Hofmann
- Institute of Virology, School of Medicine, Technical University of Munich, Germany
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Julius Luther
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Chunkyu Ko
- Institute of Virology, School of Medicine, Technical University of Munich, Germany
- Institute of Virology, Helmholtz Zentrum München, Munich, Germany
| | - Peter Zimmerman
- Department of Internal Medicine II/Molecular Biology, University Hospital Freiburg, Freiburg, Germany
| | - Volker Bruss
- Institute of Virology, Helmholtz Zentrum München, Munich, Germany
| | - Daniela Stadler
- Institute of Virology, School of Medicine, Technical University of Munich, Germany
- Institute of Virology, Helmholtz Zentrum München, Munich, Germany
| | | | - Shahinda Rezk
- Institute of Virology, School of Medicine, Technical University of Munich, Germany
- Medical Research Institute, Department of Molecular and Diagnostic Microbiology, Alexandria University, Alexandria, Egypt
| | - 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, Germany
- Institute of Virology, Helmholtz Zentrum München, Munich, Germany
- German Center for Infection Research, Munich, Germany
| | - Sabrina Schreiner
- Institute of Virology, School of Medicine, Technical University of Munich, Germany
- Institute of Virology, Hannover Medical School, Hannover, Germany
- Institute of Virology, Helmholtz Zentrum München, Munich, Germany
- German Center for Infection Research, Munich, Germany
- Cluster of Excellence RESIST (Resolving Infection Susceptibility; EXC 2155), Hannover Medical School, Hannover, Germany
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10
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Conserved Lysine Residues of Hepatitis B Virus Core Protein Are Not Required for Covalently Closed Circular DNA Formation. J Virol 2022; 96:e0071822. [PMID: 35867543 PMCID: PMC9364803 DOI: 10.1128/jvi.00718-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Hepatitis B virus (HBV) core protein (HBc), the building block of the viral capsid, plays a critical role throughout the HBV life cycle. There are two highly conserved lysine residues, namely, K7 and K96, on HBc, which have been proposed to function at various stages of viral replication, potentially through lysine-specific posttranslational modifications (PTMs). Here, we substituted K7 and K96 with alanine or arginine, which would also block potential PTMs on these two lysine residues, and tested the effects of these substitutions on HBV replication and infection. We found that the two lysine residues were dispensable for all intracellular steps of HBV replication. In particular, all mutants were competent to form the covalently closed circular DNA (cccDNA) via the intracellular amplification pathway, indicating that K7 and K96, or any PTMs of these residues, were not essential for nucleocapsid uncoating, a prerequisite for cccDNA formation. Furthermore, we found that K7A and K7R mutations did not affect de novo cccDNA formation and RNA transcription during infection, indicating that K7 or any PTMs of this residue were dispensable for HBV infection. In addition, we demonstrated that the HBc K7 coding sequence (AAA), as part of the HBV polyadenylation signal UAUAAA, was indispensable for viral RNA production, implicating this cis requirement at the RNA level, instead of any function of HBc-K7, likely constrains the identity of the 7th residue of HBc. In conclusion, our results provided novel insights regarding the roles of lysine residues on HBc, and their coding sequences, in the HBV life cycle. IMPORTANCE Hepatitis B virus (HBV) infection remains a public health burden that affects 296 million individuals worldwide. HBV core protein (HBc) is involved in almost all steps in the HBV life cycle. There are two conserved lysine residues on HBc. Here, we found that neither of them is essential for HBV intracellular replication, including the formation of covalently closed circular DNA (cccDNA), the molecular basis for establishing and sustaining the HBV infection. However, K96 is critical for virion morphogenesis, while the K7 coding sequence, but not HBc-K7 itself, is indispensable, as part of the RNA polyadenylation signal, for HBV RNA production from cccDNA. Our results provide novel insights regarding the role of the conserved lysine residues on HBc, and their coding sequences, in viral replication, and should facilitate the development of antiviral drugs against the HBV capsid protein.
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11
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Xi J, Cui X, Liu K, Liu H, Wang J, Hu J. Region-Specific Hepatitis B Virus Genome Exposure from Nucleocapsid Modulated by Capsid Linker Sequence and Inhibitor: Implications for Uncoating. J Virol 2022; 96:e0039922. [PMID: 35389266 PMCID: PMC9044944 DOI: 10.1128/jvi.00399-22] [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: 03/07/2022] [Accepted: 03/09/2022] [Indexed: 11/20/2022] Open
Abstract
Hepatitis B virus (HBV) contains a partially double-stranded, relaxed circular (RC) DNA genome synthesized within a nucleocapsid (NC) in the host cell cytoplasm. The release of RC DNA from the NC, in an ill-defined process called uncoating, to the nucleus is required for its conversion to the covalently closed circular (CCC) DNA, the viral episome serving as the transcriptional template for all viral RNAs necessary for replication and, thus, essential for establishing and sustaining viral infection. In efforts to better understand uncoating, we analyzed HBV core (HBc) mutants that show various levels of nuclear CCC DNA but little to no cytoplasmic RC DNA. We found that RC DNA could be synthesized by these mutants outside the cell, but in contrast to the wild type (wt), the mutant NCs were unable to protect RC DNA from digestion by the endogenous nuclease(s) in cellular lysates or exogenous DNase. Subcellular fractionation suggested that the major RC DNA-degrading activity was membrane associated. Digestion with sequence-specific and nonspecific DNases revealed the exposure of specific regions of RC DNA from the mutant NC. Similarly, treatment of wt NCs with a core inhibitor known to increase CCC DNA by affecting uncoating also led to region-specific exposure of RC DNA. Furthermore, a subpopulation of untreated wild type (wt) mature NCs showed site-specific exposure of RC DNA as well. Competition between RC DNA degradation and its conversion to CCC DNA during NC uncoating thus likely plays an important role in the establishment and persistence of HBV infection and has implications for the development of capsid-targeted antivirals. IMPORTANCE Disassembly of the hepatitis B virus (HBV) nucleocapsid (NC) to release its genomic DNA, in an ill-understood process called uncoating, is required to form the viral nuclear episome in the host cell nucleus, a viral DNA essential for establishing and sustaining HBV infection. The elimination of the HBV nuclear episome remains the holy grail for the development of an HBV cure. We report here that the HBV genomic DNA is exposed in a region-specific manner during uncoating, which is enhanced by mutations of the capsid protein and a capsid-targeted antiviral compound. The exposure of the viral genome can result in its rapid degradation or, alternatively, can enhance the formation of the nuclear episome, thus having a major impact on HBV infection and persistence. These results are thus important for understanding fundamental mechanisms of HBV replication and persistence and for the ongoing pursuit of an HBV cure.
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Affiliation(s)
- Ji Xi
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Xiuji Cui
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Kuancheng Liu
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Haitao Liu
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Joseph Wang
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Jianming Hu
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
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12
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Yan Y, Tang YD, Zheng C. When cyclin-dependent kinases meet viral infections, including SARS-CoV-2. J Med Virol 2022; 94:2962-2968. [PMID: 35288942 PMCID: PMC9088476 DOI: 10.1002/jmv.27719] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/18/2022] [Accepted: 02/25/2022] [Indexed: 11/16/2022]
Abstract
Cyclin‐dependent kinases (CDKs) are protein kinases that play a key role in cell division and transcriptional regulation. Recent studies have demonstrated the critical roles of CDKs in various viral infections. However, the molecular processes underpinning CDKs' roles in viral infection and host antiviral defense are unknown. This minireview briefly overviews CDKs' functions and highlights the most recent discoveries of CDKs' emerging roles during viral infections, thereby providing a scientific and theoretical foundation for antiviral regulation and shedding light on developing novel drug targets and therapeutic strategies against viral infection.
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Affiliation(s)
- Yan Yan
- Center of Clinical Laboratory, The Fifth People's Hospital of Wuxi, Affiliated Hospital of Jiangnan University, Wuxi, China
| | - Yan-Dong Tang
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China.,State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, China
| | - Chunfu Zheng
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China.,Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
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13
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Abstract
Hepatitis B virus (HBV) is a hepatotropic virus and an important human pathogen. There are an estimated 296 million people in the world that are chronically infected by this virus, and many of them will develop severe liver diseases including hepatitis, cirrhosis and hepatocellular carcinoma (HCC). HBV is a small DNA virus that replicates via the reverse transcription pathway. In this review, we summarize the molecular pathways that govern the replication of HBV and its interactions with host cells. We also discuss viral and non-viral factors that are associated with HBV-induced carcinogenesis and pathogenesis, as well as the role of host immune responses in HBV persistence and liver pathogenesis.
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Affiliation(s)
- Yu-Chen Chuang
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, CA 90089, USA
| | - Kuen-Nan Tsai
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, CA 90089, USA
| | - Jing-Hsiung James Ou
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, CA 90089, USA
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14
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Lubyova B, Tikalova E, Krulova K, Hodek J, Zabransky A, Hirsch I, Weber J. ATM-Dependent Phosphorylation of Hepatitis B Core Protein in Response to Genotoxic Stress. Viruses 2021; 13:v13122438. [PMID: 34960710 PMCID: PMC8705010 DOI: 10.3390/v13122438] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/29/2021] [Accepted: 12/02/2021] [Indexed: 12/31/2022] Open
Abstract
Chronic hepatitis caused by infection with the Hepatitis B virus is a life-threatening condition. In fact, 1 million people die annually due to liver cirrhosis or hepatocellular carcinoma. Recently, several studies demonstrated a molecular connection between the host DNA damage response (DDR) pathway and HBV replication and reactivation. Here, we investigated the role of Ataxia-telangiectasia-mutated (ATM) and Ataxia telangiectasia and Rad3-related (ATR) PI3-kinases in phosphorylation of the HBV core protein (HBc). We determined that treatment of HBc-expressing hepatocytes with genotoxic agents, e.g., etoposide or hydrogen peroxide, activated the host ATM-Chk2 pathway, as determined by increased phosphorylation of ATM at Ser1981 and Chk2 at Thr68. The activation of ATM led, in turn, to increased phosphorylation of cytoplasmic HBc at serine-glutamine (SQ) motifs located in its C-terminal domain. Conversely, down-regulation of ATM using ATM-specific siRNAs or inhibitor effectively reduced etoposide-induced HBc phosphorylation. Detailed mutation analysis of S-to-A HBc mutants revealed that S170 (S168 in a 183-aa HBc variant) is the primary site targeted by ATM-regulated phosphorylation. Interestingly, mutation of two major phosphorylation sites involving serines at positions 157 and 164 (S155 and S162 in a 183-aa HBc variant) resulted in decreased etoposide-induced phosphorylation, suggesting that the priming phosphorylation at these serine-proline (SP) sites is vital for efficient phosphorylation of SQ motifs. Notably, the mutation of S172 (S170 in a 183-aa HBc variant) had the opposite effect and resulted in massively up-regulated phosphorylation of HBc, particularly at S170. Etoposide treatment of HBV infected HepG2-NTCP cells led to increased levels of secreted HBe antigen and intracellular HBc protein. Together, our studies identified HBc as a substrate for ATM-mediated phosphorylation and mapped the phosphorylation sites. The increased expression of HBc and HBe antigens in response to genotoxic stress supports the idea that the ATM pathway may provide growth advantage to the replicating virus.
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Affiliation(s)
- Barbora Lubyova
- IOCB Gilead Research Center, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 160 00 Prague, Czech Republic; (E.T.); (K.K.); (J.H.); (A.Z.); (I.H.)
- Correspondence: (B.L.); (J.W.)
| | - Eva Tikalova
- IOCB Gilead Research Center, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 160 00 Prague, Czech Republic; (E.T.); (K.K.); (J.H.); (A.Z.); (I.H.)
| | - Kristyna Krulova
- IOCB Gilead Research Center, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 160 00 Prague, Czech Republic; (E.T.); (K.K.); (J.H.); (A.Z.); (I.H.)
| | - Jan Hodek
- IOCB Gilead Research Center, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 160 00 Prague, Czech Republic; (E.T.); (K.K.); (J.H.); (A.Z.); (I.H.)
| | - Ales Zabransky
- IOCB Gilead Research Center, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 160 00 Prague, Czech Republic; (E.T.); (K.K.); (J.H.); (A.Z.); (I.H.)
| | - Ivan Hirsch
- IOCB Gilead Research Center, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 160 00 Prague, Czech Republic; (E.T.); (K.K.); (J.H.); (A.Z.); (I.H.)
- Department of Genetics and Microbiology, Faculty of Science, Charles University, BIOCEV, 252 50 Vestec, Czech Republic
| | - Jan Weber
- IOCB Gilead Research Center, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 160 00 Prague, Czech Republic; (E.T.); (K.K.); (J.H.); (A.Z.); (I.H.)
- Correspondence: (B.L.); (J.W.)
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15
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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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16
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Abstract
Hepatitis B virus (HBV) core protein (Cp) can be found in the nucleus and cytoplasm of infected hepatocytes; however, it preferentially segregates to a specific compartment correlating with disease status. Regulation of this intracellular partitioning of Cp remains obscure. In this paper, we report that cellular compartments are filled and vacated by Cp in a time- and concentration-dependent manner in both transfections and infections. At early times after transfection, Cp, in a dimeric state, preferentially localizes to the nucleolus. Later, the nucleolar compartment is emptied and Cp progresses to being predominantly nuclear, with a large fraction of the protein in an assembled state. Nuclear localization is followed by cell-wide distribution, and then Cp becomes exclusively cytoplasmic. The same trend in Cp movement is seen during an infection. Putative nucleolar retention signals have been identified and appear to be structure dependent. Export of Cp from the nucleus involves the CRM1 exportin. Time-dependent flux can be recapitulated by modifying Cp concentration, suggesting transitions are regulated by reaching a threshold concentration.
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17
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Xi J, Luckenbaugh L, Hu J. Multiple roles of PP2A binding motif in hepatitis B virus core linker and PP2A in regulating core phosphorylation state and viral replication. PLoS Pathog 2021; 17:e1009230. [PMID: 33493210 PMCID: PMC7861550 DOI: 10.1371/journal.ppat.1009230] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 02/04/2021] [Accepted: 12/08/2020] [Indexed: 12/18/2022] Open
Abstract
Hepatitis B virus (HBV) capsid or core protein (HBc) contains an N-terminal domain (NTD) and a C-terminal domain (CTD) connected by a short linker peptide. HBc plays a critical role in virtually every step of viral replication, which is further modulated by dynamic phosphorylation and dephosphorylation of its CTD. While several cellular kinases have been identified that mediate HBc CTD phosphorylation, there is little information on the cellular phosphatases that mediate CTD dephosphorylation. Herein, a consensus binding motif for the protein phosphatase 2A (PP2A) regulatory subunit B56 was recognized within the HBc linker peptide. Mutations within this motif designed to block or enhance B56 binding showed pleiotropic effects on CTD phosphorylation state as well as on viral RNA packaging, reverse transcription, and virion secretion. Furthermore, linker mutations affected the HBV nuclear episome (the covalently closed circular or CCC DNA) differentially during intracellular amplification vs. infection. The effects of linker mutations on CTD phosphorylation state varied with different phosphorylation sites and were only partially consistent with the linker motif serving to recruit PP2A-B56, specifically, to dephosphorylate CTD, suggesting that multiple phosphatases and/or kinases may be recruited to modulate CTD (de)phosphorylation. Furthermore, pharmacological inhibition of PP2A could decrease HBc CTD dephosphorylation and increase the nuclear HBV episome. These results thus strongly implicate the HBc linker in recruiting PP2A and other host factors to regulate multiple stages of HBV replication. Hepatitis B virus (HBV) causes acute and chronic viral hepatitis, liver fibrosis, cirrhosis and cancer. The dynamic phosphorylation and dephosphorylation of the viral capsid protein (HBc), which are controlled by host cell protein kinases and phosphatases, play a critical role in regulating multiple stages of HBV replication. While a number of cellular kinases have been identified that mediate HBc phosphorylation, there is little information on cellular phosphatases that mediate its dephosphorylation. Herein we have identified a consensus binding motif in HBc for one of the major cellular phosphatases, the protein phosphatase 2A (PP2A). Genetic analysis of this motif revealed that it played multiple roles in regulating CTD phosphorylation state, as well as viral RNA packaging, reverse transcription, virion secretion, and formation of the nuclear HBV episome responsible for viral persistence. Furthermore, pharmacological inhibition of PP2A decreased HBc dephosphorylation and increased the nuclear episome, further supporting a role of PP2A in HBc dephosphorylation and HBV persistence. These results thus suggest that HBc recruits PP2A, among other host factors, to regulate HBc phosphorylation and dephosphorylation dynamics and HBV replication and persistence.
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Affiliation(s)
- Ji Xi
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Laura Luckenbaugh
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Jianming Hu
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
- * E-mail:
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18
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Shih C, Wu SY, Chou SF, Yuan TTT. Virion Secretion of Hepatitis B Virus Naturally Occurring Core Antigen Variants. Cells 2020; 10:cells10010043. [PMID: 33396864 PMCID: PMC7823318 DOI: 10.3390/cells10010043] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 12/21/2020] [Accepted: 12/28/2020] [Indexed: 02/07/2023] Open
Abstract
In natural infection, hepatitis B virus (HBV) core protein (HBc) accumulates frequent mutations. The most frequent HBc variant in chronic hepatitis B patients is mutant 97L, changing from an isoleucine or phenylalanine to a leucine (L) at HBc amino acid 97. One dogma in the HBV research field is that wild type HBV secretes predominantly virions containing mature double-stranded DNA genomes. Immature genomes, containing single-stranded RNA or DNA, do not get efficiently secreted until reaching genome maturity. Interestingly, HBc variant 97L does not follow this dogma in virion secretion. Instead, it exhibits an immature secretion phenotype, which preferentially secretes virions containing immature genomes. Other aberrant behaviors in virion secretion were also observed in different naturally occurring HBc variants. A hydrophobic pocket around amino acid 97 was identified by bioinformatics, genetic analysis, and cryo-EM. We postulated that this hydrophobic pocket could mediate the transduction of the genome maturation signal for envelopment from the capsid interior to its surface. Virion morphogenesis must involve interactions between HBc, envelope proteins (HBsAg) and host factors, such as components of ESCRT (endosomal sorting complex required for transport). Immature secretion can be offset by compensatory mutations, occurring at other positions in HBc or HBsAg. Recently, we demonstrated in mice that the persistence of intrahepatic HBV DNA is related to virion secretion regulated by HBV genome maturity. HBV virion secretion could be an antiviral drug target.
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Affiliation(s)
- Chiaho Shih
- Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
- Correspondence: (C.S.); (T.-T.T.Y.)
| | - Szu-Yao Wu
- Chimera Bioscience Inc., No. 18 Siyuan St., Zhongzheng Dist., Taipei 10087, Taiwan;
| | - Shu-Fan Chou
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA;
| | - Ta-Tung Thomas Yuan
- TFBS Bioscience, Inc. 3F, No. 103, Ln 169, Kangning St., Xizhi Dist., New Taipei City 221, Taiwan
- Correspondence: (C.S.); (T.-T.T.Y.)
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19
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Intracellular Trafficking of HBV Particles. Cells 2020; 9:cells9092023. [PMID: 32887393 PMCID: PMC7563130 DOI: 10.3390/cells9092023] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 12/15/2022] Open
Abstract
The human hepatitis B virus (HBV), that is causative for more than 240 million cases of chronic liver inflammation (hepatitis), is an enveloped virus with a partially double-stranded DNA genome. After virion uptake by receptor-mediated endocytosis, the viral nucleocapsid is transported towards the nuclear pore complex. In the nuclear basket, the nucleocapsid disassembles. The viral genome that is covalently linked to the viral polymerase, which harbors a bipartite NLS, is imported into the nucleus. Here, the partially double-stranded DNA genome is converted in a minichromosome-like structure, the covalently closed circular DNA (cccDNA). The DNA virus HBV replicates via a pregenomic RNA (pgRNA)-intermediate that is reverse transcribed into DNA. HBV-infected cells release apart from the infectious viral parrticle two forms of non-infectious subviral particles (spheres and filaments), which are assembled by the surface proteins but lack any capsid and nucleic acid. In addition, naked capsids are released by HBV replicating cells. Infectious viral particles and filaments are released via multivesicular bodies; spheres are secreted by the classic constitutive secretory pathway. The release of naked capsids is still not fully understood, autophagosomal processes are discussed. This review describes intracellular trafficking pathways involved in virus entry, morphogenesis and release of (sub)viral particles.
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20
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Viswanathan U, Mani N, Hu Z, Ban H, Du Y, Hu J, Chang J, Guo JT. Targeting the multifunctional HBV core protein as a potential cure for chronic hepatitis B. Antiviral Res 2020; 182:104917. [PMID: 32818519 DOI: 10.1016/j.antiviral.2020.104917] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 08/08/2020] [Accepted: 08/10/2020] [Indexed: 12/14/2022]
Abstract
The core (capsid) protein of hepatitis B virus (HBV) is the building block of nucleocapsids where viral DNA reverse transcriptional replication takes place and mediates virus-host cell interaction important for the persistence of HBV infection. The pleiotropic role of core protein (Cp) in HBV replication makes it an attractive target for antiviral therapies of chronic hepatitis B, a disease that affects more than 257 million people worldwide without a cure. Recent clinical studies indicate that core protein allosteric modulators (CpAMs) have a great promise as a key component of hepatitis B curative therapies. Particularly, it has been demonstrated that modulation of Cp dimer-dimer interactions by several chemical series of CpAMs not only inhibit nucleocapsid assembly and viral DNA replication, but also induce the disassembly of double-stranded DNA-containing nucleocapsids to prevent the synthesis of cccDNA. Moreover, the different chemotypes of CpAMs modulate Cp assembly by interaction with distinct amino acid residues at the HAP pocket between Cp dimer-dimer interfaces, which results in the assembly of Cp dimers into either non-capsid Cp polymers (type I CpAMs) or empty capsids with distinct physical property (type II CpAMs). The different CpAMs also differentially modulate Cp metabolism and subcellular distribution, which may impact cccDNA metabolism and host antiviral immune responses, the critical factors for the cure of chronic HBV infection. This review article highlights the recent research progress on the structure and function of core protein in HBV replication cycle, the mode of action of CpAMs, as well as the current status and perspectives on the discovery and development of core protein-targeting antivirals. This article forms part of a symposium in Antiviral Research on "Wide-ranging immune and direct-acting antiviral approaches to curing HBV and HDV infections."
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Affiliation(s)
- Usha Viswanathan
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, PA, 18902, USA
| | - Nagraj Mani
- Arbutus Biopharma Inc., 701 Veterans Circle, Warminster, PA, 18974, USA
| | - Zhanying Hu
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, PA, 18902, USA
| | - Haiqun Ban
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, PA, 18902, USA
| | - Yanming Du
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, PA, 18902, USA
| | - Jin Hu
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, PA, 18902, USA
| | - Jinhong Chang
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, PA, 18902, USA
| | - Ju-Tao Guo
- Baruch S. Blumberg Institute, 3805 Old Easton Road, Doylestown, PA, 18902, USA.
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21
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Hu Z, Ban H, Zheng H, Liu M, Chang J, Guo JT. Protein phosphatase 1 catalyzes HBV core protein dephosphorylation and is co-packaged with viral pregenomic RNA into nucleocapsids. PLoS Pathog 2020; 16:e1008669. [PMID: 32702076 PMCID: PMC7402523 DOI: 10.1371/journal.ppat.1008669] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 08/04/2020] [Accepted: 05/30/2020] [Indexed: 01/01/2023] Open
Abstract
Hepatitis B virus (HBV) replicates its genomic DNA via viral DNA polymerase self-primed reverse transcription of a RNA pre-genome in the nucleocapsid assembled by 120 core protein (Cp) dimers. The arginine-rich carboxyl-terminal domain (CTD) of Cp plays an important role in the selective packaging of viral DNA polymerase-pregenomic (pg) RNA complex into nucleocapsid. Previous studies suggested that the CTD is initially phosphorylated at multiple sites to facilitate viral RNA packaging and subsequently dephosphorylated in association with viral DNA synthesis and secretion of DNA-containing virions. However, our recent studies suggested that Cp is hyper-phosphorylated as free dimers and its dephosphorylation is associated with pgRNA encapsidation. Herein, we provide further genetic and biochemical evidence supporting that extensive Cp dephosphorylation does take place during the assembly of pgRNA-containing nucleocapsids, but not empty capsids. Moreover, we found that cellular protein phosphatase 1 (PP1) is required for Cp dephosphorylation and pgRNA packaging. Interestingly, the PP1 catalytic subunits α and β were packaged into pgRNA-containing nucleocapsids, but not empty capsids, and treatment of HBV replicating cells with core protein allosteric modulators (CpAMs) promoted empty capsid assembly and abrogated the encapsidation of PP1 α and β. Our study thus identified PP1 as a host cellular factor that is co-packaged into HBV nucleocapsids, and plays an essential role in selective packaging of the viral DNA-polymerase-pgRNA complex through catalyzing Cp dephosphorylation. Selective packaging of pregenomic RNA by core protein dimers into nucleocapsid is a key step of HBV replication and is subjected for the regulation by multiple viral and host cellular factors. HBV core protein phosphorylation and dephosphorylation play an essential role in HBV genome replication. However, the cellular kinases and phosphatases responsible for the biochemical events remain elusive. Identification of cellular protein phosphatase 1 as a host cellular factor catalyzing core protein dephosphorylation and facilitating viral pregenomic RNA packaging into nucleocapsids sheds new light on the molecular mechanism of HBV replication and development of therapeutics to cure chronic HBV infection.
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Affiliation(s)
- Zhanying Hu
- Department of Experimental Therapeutics, Baruch S. Blumberg Institute, Doylestown, Pennsylvania, United States of America
| | - Haiqun Ban
- Department of Experimental Therapeutics, Baruch S. Blumberg Institute, Doylestown, Pennsylvania, United States of America
| | - Haiyan Zheng
- Biological mass spectrometry facility, Robert Wood Johnson Medical School and Rutgers, The State University of New Jersey. Piscataway, New Jersey, United States of America
| | - Mingliang Liu
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Tian-Tan Xi-Li, Beijing, China
| | - Jinhong Chang
- Department of Experimental Therapeutics, Baruch S. Blumberg Institute, Doylestown, Pennsylvania, United States of America
| | - Ju-Tao Guo
- Department of Experimental Therapeutics, Baruch S. Blumberg Institute, Doylestown, Pennsylvania, United States of America
- * E-mail:
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22
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Phosphorylation of the Arginine-Rich C-Terminal Domains of the Hepatitis B Virus (HBV) Core Protein as a Fine Regulator of the Interaction between HBc and Nucleic Acid. Viruses 2020; 12:v12070738. [PMID: 32650547 PMCID: PMC7412469 DOI: 10.3390/v12070738] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/02/2020] [Accepted: 07/03/2020] [Indexed: 02/08/2023] Open
Abstract
The morphogenesis of Hepatitis B Virus (HBV) viral particles is nucleated by the oligomerization of HBc protein molecules, resulting in the formation of an icosahedral capsid shell containing the replication-competent nucleoprotein complex made of the viral polymerase and the pre-genomic RNA (pgRNA). HBc is a phospho-protein containing two distinct domains acting together throughout the viral replication cycle. The N-terminal domain, (residues 1–140), shown to self-assemble, is linked by a short flexible domain to the basic C-terminal domain (residues 150–183) that interacts with nucleic acids (NAs). In addition, the C-terminal domain contains a series of phospho-acceptor residues that undergo partial phosphorylation and de-phosphorylation during virus replication. This highly dynamic process governs the homeostatic charge that is essential for capsid stability, pgRNA packaging and to expose the C-terminal domain at the surface of the particles for cell trafficking. In this review, we discuss the roles of the N-terminal and C-terminal domains of HBc protein during HBV morphogenesis, focusing on how the C-terminal domain phosphorylation dynamics regulate its interaction with nucleic acids throughout the assembly and maturation of HBV particles.
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23
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Eller C, Heydmann L, Colpitts CC, El Saghire H, Piccioni F, Jühling F, Majzoub K, Pons C, Bach C, Lucifora J, Lupberger J, Nassal M, Cowley GS, Fujiwara N, Hsieh SY, Hoshida Y, Felli E, Pessaux P, Sureau C, Schuster C, Root DE, Verrier ER, Baumert TF. A genome-wide gain-of-function screen identifies CDKN2C as a HBV host factor. Nat Commun 2020; 11:2707. [PMID: 32483149 PMCID: PMC7264273 DOI: 10.1038/s41467-020-16517-w] [Citation(s) in RCA: 9] [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: 06/24/2019] [Accepted: 05/03/2020] [Indexed: 12/21/2022] Open
Abstract
Chronic HBV infection is a major cause of liver disease and cancer worldwide. Approaches for cure are lacking, and the knowledge of virus-host interactions is still limited. Here, we perform a genome-wide gain-of-function screen using a poorly permissive hepatoma cell line to uncover host factors enhancing HBV infection. Validation studies in primary human hepatocytes identified CDKN2C as an important host factor for HBV replication. CDKN2C is overexpressed in highly permissive cells and HBV-infected patients. Mechanistic studies show a role for CDKN2C in inducing cell cycle G1 arrest through inhibition of CDK4/6 associated with the upregulation of HBV transcription enhancers. A correlation between CDKN2C expression and disease progression in HBV-infected patients suggests a role in HBV-induced liver disease. Taken together, we identify a previously undiscovered clinically relevant HBV host factor, allowing the development of improved infectious model systems for drug discovery and the study of the HBV life cycle.
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Affiliation(s)
- Carla Eller
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
| | - Laura Heydmann
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
| | - Che C Colpitts
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Houssein El Saghire
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
| | - Federica Piccioni
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, USA
| | - Frank Jühling
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
| | - Karim Majzoub
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
| | - Caroline Pons
- Inserm, U1052, Cancer Research Center of Lyon (CRCL), Université de Lyon (UCBL1), CNRS UMR_5286, Centre Léon Bérard, Lyon, France
| | - Charlotte Bach
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
| | - Julie Lucifora
- Inserm, U1052, Cancer Research Center of Lyon (CRCL), Université de Lyon (UCBL1), CNRS UMR_5286, Centre Léon Bérard, Lyon, France
| | - Joachim Lupberger
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
| | - Michael Nassal
- Department of Internal Medicine II/Molecular Biology, University Hospital Freiburg, Freiburg, Germany
| | - Glenn S Cowley
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, USA
| | - Naoto Fujiwara
- Liver Tumor Translational Research Program, Simmons Comprehensive Cancer Center, Division of Digestive and Liver Diseases, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Sen-Yung Hsieh
- Department of Gastroenterology and Hepatology, Chang Gung Memorial Hospital, Taipei, Taiwan
| | - Yujin Hoshida
- Liver Tumor Translational Research Program, Simmons Comprehensive Cancer Center, Division of Digestive and Liver Diseases, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Emanuele Felli
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
- Institut Hospitalo-Universitaire, Pôle Hépato-digestif, Nouvel Hôpital Civil, 67000, Strasbourg, France
| | - Patrick Pessaux
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
- Institut Hospitalo-Universitaire, Pôle Hépato-digestif, Nouvel Hôpital Civil, 67000, Strasbourg, France
| | - Camille Sureau
- Laboratoire de Virologie Moléculaire, INTS, Paris, France
| | - Catherine Schuster
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France
| | - David E Root
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, USA
| | - Eloi R Verrier
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France.
| | - Thomas F Baumert
- Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000, Strasbourg, France.
- Institut Hospitalo-Universitaire, Pôle Hépato-digestif, Nouvel Hôpital Civil, 67000, Strasbourg, France.
- Institut Universitaire de France (IUF), Paris, France.
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24
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Luo J, Xi J, Gao L, Hu J. Role of Hepatitis B virus capsid phosphorylation in nucleocapsid disassembly and covalently closed circular DNA formation. PLoS Pathog 2020; 16:e1008459. [PMID: 32226051 PMCID: PMC7145273 DOI: 10.1371/journal.ppat.1008459] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 04/09/2020] [Accepted: 03/05/2020] [Indexed: 12/16/2022] Open
Abstract
Hepatitis B virus (HBV) delivers a partially double-stranded, relaxed circular (RC) DNA genome in complete virions to the host cell nucleus for conversion to the covalently closed circular (CCC) DNA, which establishes and sustains viral infection. An overlength pregenomic RNA (pgRNA) is then transcribed from CCC DNA and packaged into immature nucleocapsids (NCs) by the viral core (HBc) protein. pgRNA is reverse transcribed to produce RC DNA in mature NCs, which are then enveloped and secreted as complete virions, or delivered to the nucleus to replenish the nuclear CCC DNA pool. RC DNA, whether originating from extracellular virions or intracellular mature NCs, must be released upon NC disassembly (uncoating) for CCC DNA formation. HBc is known to undergo dynamic phosphorylation and dephosphorylation at its C-terminal domain (CTD) to facilitate pgRNA packaging and reverse transcription. Here, two putative phosphorylation sites in the HBc N-terminal domain (NTD), S44 and S49, were targeted for genetic and biochemical analysis to assess their potential roles in viral replication. The NTD mutant that mimics the non-phosphorylated state (N2A) was competent in all steps of viral replication tested from capsid assembly, pgRNA packaging, reverse transcription, to virion secretion, except for a decrease in CCC DNA formation. On the other hand, the phosphor-mimetic mutant N2E showed a defect in the early step of pgRNA packaging but enhanced the late step of mature NC uncoating and consequently, increased CCC DNA formation. N2E also enhanced phosphorylation in CTD and possibly elsewhere in HBc. Furthermore, inhibition of the cyclin-dependent kinase 2 (CDK2), which is packaged into viral capsids, could block CCC DNA formation. These results prompted us to propose a model whereby rephosphorylation of HBc at both NTD and CTD by the packaged CDK2, following CTD dephosphorylation during NC maturation, facilitates uncoating and CCC DNA formation by destabilizing mature NCs.
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Affiliation(s)
- Jun Luo
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Ji Xi
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Lu Gao
- Roche Pharma Research and Early Development, Roche Innovation Center Shanghai, Shanghai, China
| | - Jianming Hu
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
- * E-mail:
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25
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Nishi M, Miyakawa K, Matsunaga S, Khatun H, Yamaoka Y, Watashi K, Sugiyama M, Kimura H, Wakita T, Ryo A. Prolyl Isomerase Pin1 Regulates the Stability of Hepatitis B Virus Core Protein. Front Cell Dev Biol 2020; 8:26. [PMID: 32083080 PMCID: PMC7005485 DOI: 10.3389/fcell.2020.00026] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/14/2020] [Indexed: 01/14/2023] Open
Abstract
The dynamic interplay between virus and host proteins is critical for establishing efficient viral replication and virus-induced pathogenesis. Phosphorylation-dependent prolyl isomerization by Pin1 provides a unique mechanism of molecular switching to control both protein function and stability. We demonstrate here that Pin1 binds and stabilizes hepatitis B virus core protein (HBc) in a phosphorylation-dependent manner, and promotes the efficient viral propagation. Phos-tag gel electrophoresis with various site-directed mutants of HBc revealed that Thr160 and Ser162 residues within the C terminal arginine-rich domain are phosphorylated concomitantly. GST pull-down assay and co-immunoprecipitation analysis demonstrated that Pin1 associated with phosphorylated HBc at the Thr160-Pro and Ser162-Pro motifs. Chemical or genetic inhibition of Pin1 significantly accelerated the rapid degradation of HBc via a lysosome-dependent pathway. Furthermore, we found that the pyruvate dehydrogenase phosphatase catalytic subunit 2 (PDP2) could dephosphorylate HBc at the Pin1-binding sites, thereby suppressing Pin1-mediated HBc stabilization. Our findings reveal an important regulatory mechanism of HBc stability catalyzed by Pin1 and may facilitate the development of new antiviral therapeutics targeting Pin1 function.
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Affiliation(s)
- Mayuko Nishi
- Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan
| | - Kei Miyakawa
- Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan
| | - Satoko Matsunaga
- Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan
| | - Hajera Khatun
- Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan
| | - Yutaro Yamaoka
- Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan.,Isehara Research Laboratory, Technology and Development Division, Kanto Chemical Co., Inc., Isehara, Japan
| | - Koichi Watashi
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Masaya Sugiyama
- Genome Medical Sciences Project, National Center for Global Health and Medicine, Chiba, Japan
| | - Hirokazu Kimura
- Faculty of Health Sciences, School of Medical Technology, Gunma Paz University, Takasaki, Japan
| | - Takaji Wakita
- Genome Medical Sciences Project, National Center for Global Health and Medicine, Chiba, Japan
| | - Akihide Ryo
- Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan
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26
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Xiao Y, Liu C, Tang W, Zhang H, Chen X. Evans Blue Inhibits HBV Replication Through a Dual Antiviral Mechanism by Targeting Virus Binding and Capsid Assembly. Front Microbiol 2019; 10:2638. [PMID: 31798562 PMCID: PMC6868041 DOI: 10.3389/fmicb.2019.02638] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/30/2019] [Indexed: 12/29/2022] Open
Abstract
Chronic hepatitis B (CHB) is a global health problem caused by human hepatitis B virus (HBV). Current treatment with interferons and nucleos(t)ide analogs (NAs) can cause population tolerance and drug resistance. Therefore, new antiviral drugs, especially those targeting host factors, are urgently needed. Here, we identified Evans blue as a new HBV inhibitor by screening an FDA drug library using Huh7DhNTCP cells and confirmed the antiviral activity in primary human hepatocytes and human sodium taurocholate cotransporting polypeptide (hNTCP)-transfected porcine primary hepatocytes. Our efficacy study showed that Evans blue has an IC50 of 2 μM against HBV infection in Huh7DhNTCP cells, and no apparent toxicity at up to 1000 μM. The IC50 of Evans blue against HBV in primary human hepatocytes was approximately 5 μM. Mechanism studies revealed that Evans blue has a dual anti-HBV effect. It inhibits both the binding of viral preS1 to host cells through the host factor NTCP and the virus capsid assembly by targeting the host factor BK channel. The KD of the direct interaction between Evans blue and NTCP is 8.82E-8 M. Evans blue can suppress capsid assembly at micromolar concentrations by reducing the cytosolic calcium ion concentration. Since the antiviral effects on HBV binding and assembly are both achieved through targeting host factors, Evans blue inhibits the infection of nucleos(t)ide analog drug-resistant HBV strains in Huh7DhNTCP cells. Taken together, our results suggest that Evans blue may be a promising anti-HBV drug candidate in the classes of both entry and assembly inhibitors.
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Affiliation(s)
- Yu Xiao
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Chunlan Liu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Wei Tang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Haiwei Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Xulin Chen
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China.,Guangdong Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
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27
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Jeong GU, Ahn BY. Aurora kinase A promotes hepatitis B virus replication and expression. Antiviral Res 2019; 170:104572. [DOI: 10.1016/j.antiviral.2019.104572] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/22/2019] [Accepted: 07/30/2019] [Indexed: 12/16/2022]
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28
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Abstract
With a yearly death toll of 880,000, hepatitis B virus (HBV) remains a major health problem worldwide, despite an effective prophylactic vaccine and well-tolerated, effective antivirals. HBV causes chronic hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. The viral genome persists in infected hepatocytes even after long-term antiviral therapy, and its integration, though no longer able to support viral replication, destabilizes the host genome. HBV is a DNA virus that utilizes a virus-encoded reverse transcriptase to convert an RNA intermediate, termed pregenomic RNA, into the relaxed circular DNA genome, which is subsequently converted into a covalently closed circular DNA (cccDNA) in the host cell nucleus. cccDNA is maintained in the nucleus of the infected hepatocyte as a stable minichromosome and functions as the viral transcriptional template for the production of all viral gene products, and thus, it is the molecular basis of HBV persistence. The nuclear cccDNA pool can be replenished through recycling of newly synthesized, DNA-containing HBV capsids. Licensed antivirals target the HBV reverse transcriptase activity but fail to eliminate cccDNA, which would be required to cure HBV infection. Elimination of HBV cccDNA is so far only achieved by antiviral immune responses. Thus, this review will focus on possible curative strategies aimed at eliminating or crippling the viral cccDNA. Newer insights into the HBV life cycle and host immune response provide novel, potentially curative therapeutic opportunities and targets.
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29
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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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30
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RNA-Binding Motif Protein 24 (RBM24) Is Involved in Pregenomic RNA Packaging by Mediating Interaction between Hepatitis B Virus Polymerase and the Epsilon Element. J Virol 2019; 93:JVI.02161-18. [PMID: 30626666 DOI: 10.1128/jvi.02161-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 12/18/2018] [Indexed: 12/14/2022] Open
Abstract
Encapsidation of pregenomic RNA (pgRNA) is a crucial step in hepatitis B virus (HBV) replication. Binding by viral polymerase (Pol) to the epsilon stem-loop (ε) on the 5'-terminal region (TR) of pgRNA is required for pgRNA packaging. However, the detailed mechanism is not well understood. RNA-binding motif protein 24 (RBM24) inhibits core translation by binding to the 5'-TR of pgRNA. Here, we demonstrate that RBM24 is also involved in pgRNA packaging. RBM24 directly binds to the lower bulge of ε via RNA recognition submotifs (RNPs). RBM24 also interacts with Pol in an RNA-independent manner. The alanine-rich domain (ARD) of RBM24 and the reverse transcriptase (RT) domain of Pol are essential for binding between RBM24 and Pol. In addition, overexpression of RBM24 increases Pol-ε interaction, whereas RBM24 knockdown decreases the interaction. RBM24 was able to rescue binding between ε and mutant Pol lacking ε-binding activity, further showing that RBM24 mediates the interaction between Pol and ε by forming a Pol-RBM24-ε complex. Finally, RBM24 significantly promotes the packaging efficiency of pgRNA. In conclusion, RBM24 mediates Pol-ε interaction and formation of a Pol-RBM24-ε complex, which inhibits translation of pgRNA and results in pgRNA packing into capsids/virions for reverse transcription and DNA synthesis.IMPORTANCE Hepatitis B virus (HBV) is a ubiquitous human pathogen, and HBV infection is a major global health burden. Chronic HBV infection is associated with the development of liver diseases, including fulminant hepatitis, hepatic fibrosis, cirrhosis, and hepatocellular carcinoma. A currently approved vaccine can prevent HBV infection, and medications are able to reduce viral loads and prevent liver disease progression. However, current treatments rarely achieve a cure for chronic infection. Thus, it is important to gain insight into the mechanisms of HBV replication. In this study, we found that the host factor RBM24 is involved in pregenomic RNA (pgRNA) packaging and regulates HBV replication. These findings highlight a potential target for antiviral therapeutics of HBV infection.
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31
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Heger-Stevic J, Zimmermann P, Lecoq L, Böttcher B, Nassal M. Hepatitis B virus core protein phosphorylation: Identification of the SRPK1 target sites and impact of their occupancy on RNA binding and capsid structure. PLoS Pathog 2018; 14:e1007488. [PMID: 30566530 PMCID: PMC6317823 DOI: 10.1371/journal.ppat.1007488] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 01/03/2019] [Accepted: 11/27/2018] [Indexed: 12/19/2022] Open
Abstract
Hepatitis B virus (HBV) replicates its 3 kb DNA genome through capsid-internal reverse transcription, initiated by assembly of 120 core protein (HBc) dimers around a complex of viral pregenomic (pg) RNA and polymerase. Following synthesis of relaxed circular (RC) DNA capsids can be enveloped and secreted as stable virions. Upon infection of a new cell, however, the capsid disintegrates to release the RC-DNA into the nucleus for conversion into covalently closed circular (ccc) DNA. HBc´s interactions with nucleic acids are mediated by an arginine-rich C terminal domain (CTD) with intrinsically strong non-specific RNA binding activity. Adaptation to the changing demands for nucleic acid binding during the viral life cycle is thought to involve dynamic phosphorylation / dephosphorylation events. However, neither the relevant enzymes nor their target sites in HBc are firmly established. Here we developed a bacterial coexpression system enabling access to definably phosphorylated HBc. Combining Phos-tag gel electrophoresis, mass spectrometry and mutagenesis we identified seven of the eight hydroxy amino acids in the CTD as target sites for serine-arginine rich protein kinase 1 (SRPK1); fewer sites were phosphorylated by PKA and PKC. Phosphorylation of all seven sites reduced nonspecific RNA encapsidation as drastically as deletion of the entire CTD and altered CTD surface accessibility, without major structure changes in the capsid shell. The bulk of capsids from human hepatoma cells was similarly highly, yet non-identically, phosphorylated as by SRPK1. While not proving SRPK1 as the infection-relevant HBc kinase the data suggest a mechanism whereby high-level HBc phosphorylation principally suppresses RNA binding whereas one or few strategic dephosphorylation events enable selective packaging of the pgRNA/polymerase complex. The tools developed in this study should greatly facilitate the further deciphering of the role of HBc phosphorylation in HBV infection and its evaluation as a potential new therapeutic target.
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Affiliation(s)
- Julia Heger-Stevic
- University Hospital Freiburg, Department of Medicine II / Molecular Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Biological Faculty, University of Freiburg, Freiburg, Germany
| | - Peter Zimmermann
- University Hospital Freiburg, Department of Medicine II / Molecular Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Biological Faculty, University of Freiburg, Freiburg, Germany
| | - Lauriane Lecoq
- Institut de Biologie et Chimie des Protéines, University of Lyon1, Lyon, France
| | - Bettina Böttcher
- Department of Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany
| | - Michael Nassal
- University Hospital Freiburg, Department of Medicine II / Molecular Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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32
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Yang F. Post-translational Modification Control of HBV Biological Processes. Front Microbiol 2018; 9:2661. [PMID: 30443247 PMCID: PMC6222169 DOI: 10.3389/fmicb.2018.02661] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 10/18/2018] [Indexed: 12/11/2022] Open
Abstract
Hepatitis B virus infection remains a global healthy issue that needs to be urgently solved. Novel strategies for anti-viral therapy are based on exploring the effective diagnostic markers and therapeutic targets of diseases caused by hepatitis B virus (HBV) infection. It is well-established that not only viral proteins themselves but also key factors from the host control the biological processes associated with HBV, including replication, transcription, packaging, and secretion. Protein post-translational modifications (PTMs), such as phosphorylation, acetylation, methylation, and ubiquitination, have been shown to control protein activity, regulate protein stability, promote protein interactions and alter protein subcellular localization, leading to the modulation of crucial signaling pathways and affected cellular processes. This review focuses on the functions and effects of diverse PTMs in regulating important processes in the HBV life cycle. The potential roles of PTMs in the pathogenesis of HBV-associated liver diseases are also discussed.
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Affiliation(s)
- Fan Yang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
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33
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Nair S, Li L, Francis S, Turner WW, VanNieuwenhze M, Zlotnick A. Use of a Fluorescent Analogue of a HBV Core Protein-Directed Drug To Interrogate an Antiviral Mechanism. J Am Chem Soc 2018; 140:15261-15269. [PMID: 30375863 DOI: 10.1021/jacs.8b07988] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Heteroaryldihydropyrimidines (HAPs) are antiviral small molecules that enhance assembly of HBV core protein (Cp), lead to assembly of empty and defective particles, and suppress viral replication. These core protein allosteric modulators (CpAMs) bind to the pocket at the interface between two Cp dimers and strengthen interdimer interactions. To investigate the CpAM mechanism, we wanted to examine the cellular distributions of Cp and the CpAM itself. For this reason, we developed a fluorescently labeled CpAM, HAP-ALEX. In vitro, HAP-ALEX modulated assembly of purified Cp and at saturating concentrations induced formation of large structures. HAP-ALEX bound capsids and not dimers, making it a capsid-specific molecular tag. HAP-ALEX labeled HBV in transfected cells, with no detectable background with a HAP-insensitive Cp mutant. HAP-ALEX caused redistribution of Cp in a dose-dependent manner consistent with its 0.7 μM EC50, leading to formation of large puncta and an exclusively cytoplasmic distribution. HAP-ALEX colocalized with the redistributed Cp, but large puncta accumulated long before they appeared saturated with the fluorescent CpAM. CpAMs affect HBV assembly and localization; with a fluorescent CpAM both drug and target can be identified.
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Affiliation(s)
- Smita Nair
- Molecular and Cellular Biochemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Lichun Li
- Molecular and Cellular Biochemistry , Indiana University , Bloomington , Indiana 47405 , United States.,Assembly BioSciences , Carmel , Indiana 45032 , United States
| | - Samson Francis
- Assembly BioSciences , Carmel , Indiana 45032 , United States
| | - William W Turner
- Molecular and Cellular Biochemistry , Indiana University , Bloomington , Indiana 47405 , United States.,Assembly BioSciences , Carmel , Indiana 45032 , United States
| | - Michael VanNieuwenhze
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Adam Zlotnick
- Molecular and Cellular Biochemistry , Indiana University , Bloomington , Indiana 47405 , United States
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34
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Mitra B, Thapa RJ, Guo H, Block TM. Host functions used by hepatitis B virus to complete its life cycle: Implications for developing host-targeting agents to treat chronic hepatitis B. Antiviral Res 2018; 158:185-198. [PMID: 30145242 PMCID: PMC6193490 DOI: 10.1016/j.antiviral.2018.08.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 08/21/2018] [Accepted: 08/22/2018] [Indexed: 02/06/2023]
Abstract
Similar to other mammalian viruses, the life cycle of hepatitis B virus (HBV) is heavily dependent upon and regulated by cellular (host) functions. These cellular functions can be generally placed in to two categories: (a) intrinsic host restriction factors and innate defenses, which must be evaded or repressed by the virus; and (b) gene products that provide functions necessary for the virus to complete its life cycle. Some of these functions may apply to all viruses, but some may be specific to HBV. In certain cases, the virus may depend upon the host function much more than does the host itself. Knowing which host functions regulate the different steps of a virus' life cycle, can lead to new antiviral targets and help in developing novel treatment strategies, in addition to improving a fundamental understanding of viral pathogenesis. Therefore, in this review we will discuss known host factors which influence key steps of HBV life cycle, and further elucidate therapeutic interventions targeting host-HBV interactions.
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Affiliation(s)
- Bidisha Mitra
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, USA
| | | | - Haitao Guo
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, USA.
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35
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Hepatitis B Virus Core Protein Dephosphorylation Occurs during Pregenomic RNA Encapsidation. J Virol 2018; 92:JVI.02139-17. [PMID: 29669831 DOI: 10.1128/jvi.02139-17] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 04/11/2018] [Indexed: 12/12/2022] Open
Abstract
Hepatitis B virus (HBV) core protein consists of an N-terminal assembly domain and a C-terminal domain (CTD) with seven conserved serines or threonines that are dynamically phosphorylated/dephosphorylated during the viral replication cycle. Sulfamoylbenzamide derivatives are small molecular core protein allosteric modulators (CpAMs) that bind to the heteroaryldihydropyrimidine (HAP) pocket between the core protein dimer-dimer interfaces. CpAM binding alters the kinetics and pathway of capsid assembly and can result in the formation of morphologically "normal" capsids devoid of viral pregenomic RNA (pgRNA) and DNA polymerase. In order to investigate the mechanism underlying CpAM inhibition of pgRNA encapsidation, we developed an immunoblotting assay that can resolve core protein based on its phosphorylation status and demonstrated, for the first time, that core protein is hyperphosphorylated in free dimers and empty capsids from both mock-treated and CpAM-treated cells but is hypophosphorylated in pgRNA- and DNA-containing nucleocapsids. Interestingly, inhibition of pgRNA encapsidation by a heat shock protein 90 (HSP90) inhibitor prevented core protein dephosphorylation. Moreover, core proteins with point mutations at the wall of the HAP pocket, V124A and V124W, assembled empty capsids and nucleocapsids with altered phosphorylation status. The results thus suggest that core protein dephosphorylation occurs in the assembly of pgRNA and that interference with the interaction between core protein subunits at dimer-dimer interfaces during nucleocapsid assembly alters not only capsid structure, but also core protein dephosphorylation. Hence, inhibition of pgRNA encapsidation by CpAMs might be due to disruption of core protein dephosphorylation during nucleocapsid assembly.IMPORTANCE Dynamic phosphorylation of HBV core protein regulates multiple steps of viral replication. However, the regulatory function was mainly investigated by phosphomimetic mutagenesis, which disrupts the natural dynamics of core protein phosphorylation/dephosphorylation. Development of an immunoblotting assay capable of resolving hyper- and hypophosphorylated core proteins allowed us to track the phosphorylation status of core proteins existing as free dimers and the variety of intracellular capsids and to investigate the role of core protein phosphorylation/dephosphorylation in viral replication. Here, we found that disruption of core protein interaction at dimer-dimer interfaces during nucleocapsid assembly (by CpAMs or mutagenesis) inhibited core protein dephosphorylation and pgRNA packaging. Our work has thus revealed a novel function of core protein dephosphorylation in HBV replication and the mechanism by which CpAMs, a class of compounds that are currently in clinical trials for treatment of chronic hepatitis B, induce the assembly of empty capsids.
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Hu J, Qiao M, Chen Y, Tang H, Zhang W, Tang D, Pi S, Dai J, Tang N, Huang A, Hu Y. Cyclin E2-CDK2 mediates SAMHD1 phosphorylation to abrogate its restriction of HBV replication in hepatoma cells. FEBS Lett 2018; 592:1893-1904. [PMID: 29782647 DOI: 10.1002/1873-3468.13105] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 04/28/2018] [Accepted: 05/12/2018] [Indexed: 12/19/2022]
Abstract
SAMHD1 inhibits Hepatitis B virus (HBV) replication by reducing the intracellular dNTP levels. However, how SAMHD1 phosphorylation is regulated to abrogate its restriction of HBV replication in hepatoma cells is poorly understood. Here, we show that HBV replication and SAMHD1 phosphorylation levels are significantly reduced by knocking down cyclin-dependent kinase (CDK) 2 expression or in the presence of a CDK2 inhibitor. SAMHD1 binds to CDK2 in hepatocarcinoma cells, and this interaction does not require the HBV core protein. Furthermore, cyclin E2 participates in regulating viral replication through the CDK2/SAMHD1 phosphorylation pathway in an HBV infection system. Collectively, our results provide evidence that CDK2 has a greater role in regulating SAMHD1 phosphorylation and HBV replication than CDK1 or CDK6.
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Affiliation(s)
- Jie Hu
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
| | - Miao Qiao
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
| | - Yanmeng Chen
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
| | - Hua Tang
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
| | - Wenlu Zhang
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
| | - Dan Tang
- Endocrinology Department, Chengdu First People's Hospital, Chengdu, China
| | - Sidie Pi
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
| | - Juan Dai
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
| | - Ni Tang
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
| | - Ailong Huang
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
| | - Yuan Hu
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Department of Infectious Diseases, Institute for Viral Hepatitis, Second Affiliated Hospital, Chongqing Medical University, China
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37
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Liu K, Hu J. Host-regulated Hepatitis B Virus Capsid Assembly in a Mammalian Cell-free System. Bio Protoc 2018; 8:e2813. [PMID: 29770355 DOI: 10.21769/bioprotoc.2813] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The hepatitis B virus (HBV) is an important global human pathogen and represents a major cause of hepatitis, liver cirrhosis and liver cancer. The HBV capsid is composed of multiple copies of a single viral protein, the capsid or core protein (HBc), plays multiple roles in the viral life cycle, and has emerged recently as a major target for developing antiviral therapies against HBV infection. Although several systems have been developed to study HBV capsid assembly, including heterologous overexpression systems like bacteria and insect cells, in vitro assembly using purified protein, and mammalian cell culture systems, the requirement for non-physiological concentrations of HBc and salts and the difficulty in manipulating host regulators of assembly presents major limitations for detailed studies on capsid assembly under physiologically relevant conditions. We have recently developed a mammalian cell-free system based on the rabbit reticulocyte lysate (RRL), in which HBc is expressed at physiological concentrations and assembles into capsids under near-physiological conditions. This system has already revealed HBc assembly requirements that are not anticipated based on previous assembly systems. Furthermore, capsid assembly in this system is regulated by endogenous host factors that can be readily manipulated. Here we present a detailed protocol for this cell-free capsid assembly system, including an illustration on how to manipulate host factors that regulate assembly.
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Affiliation(s)
- Kuancheng Liu
- College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, China.,Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA, USA
| | - Jianming Hu
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA, USA
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38
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Diab A, Foca A, Fusil F, Lahlali T, Jalaguier P, Amirache F, N'Guyen L, Isorce N, Cosset FL, Zoulim F, Andrisani O, Durantel D. Polo-like-kinase 1 is a proviral host factor for hepatitis B virus replication. Hepatology 2017; 66:1750-1765. [PMID: 28445592 PMCID: PMC5658273 DOI: 10.1002/hep.29236] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 03/17/2017] [Accepted: 04/18/2017] [Indexed: 12/13/2022]
Abstract
Chronic hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC) and current treatments for chronic hepatitis B and HCC are suboptimal. Herein, we identified cellular serine/threonine Polo-like-kinase 1 (PLK1) as a positive effector of HBV replication. The aim of this study was to demonstrate the proviral role of PLK1 in HBV biosynthesis and validate PLK1 inhibition a potential antiviral strategy. To this end, we employed physiologically relevant HBV infection models of primary human hepatocytes (PHHs) and differentiated HepaRG cells in conjunction with pharmacologic PLK1 inhibitors, small interfering RNA (siRNA)-mediated knockdown, and overexpression of constitutively active PLK1 (PLK1CA ). In addition, a humanized liver Fah-/- /Rag2-/- /Il2rg-/- (FRG) mouse model was used to determine the antiviral effect of PLK1 inhibitor BI-2536 on HBV infection in vivo. Finally, in vitro PLK1 kinase assays and site-directed mutagenesis were employed to demonstrate that HBV core protein (HBc) is a PLK1 substrate. We demonstrated that HBV infection activated cellular PLK1 in PHHs and differentiated HepaRG cells. PLK1 inhibition by BI-2536 or siRNA-mediated knockdown suppressed HBV DNA biosynthesis, whereas overexpression of PLK1CA increased it, suggesting that the PLK1 effects on viral biosynthesis are specific and that PLK1 is a proviral cellular factor. Significantly, BI-2536 administration to HBV-infected humanized liver FRG mice strongly inhibited HBV infection, validating PLK1 as an antiviral target in vivo. The proviral action of PLK1 is associated with the biogenesis of the nucleocapsid, as BI-2536 leads to its decreased intracellular formation/accumulation. In this respect, our studies identified HBc as a PLK1 substrate in vitro, and mapped PLK1 phosphorylation sites on this protein. CONCLUSION PLK1 is a proviral host factor that could be envisaged as a target for combined antiviral and antitumoral strategies against HBV infection and HBV-mediated carcinogenesis. (Hepatology 2017;66:1750-1765).
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Affiliation(s)
- Ahmed Diab
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- Department of Basic Medical Sciences and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN
| | - Adrien Foca
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - Floriane Fusil
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- CIRI-International Center for Infectiology Research, Team EVIR, INSERM, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univirsity of Lyon, Lyon, France
| | - Thomas Lahlali
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - Pascal Jalaguier
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - Fouzia Amirache
- CIRI-International Center for Infectiology Research, Team EVIR, INSERM, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univirsity of Lyon, Lyon, France
| | - Lia N'Guyen
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - Nathalie Isorce
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - François-Loïc Cosset
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- CIRI-International Center for Infectiology Research, Team EVIR, INSERM, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univirsity of Lyon, Lyon, France
| | - Fabien Zoulim
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- Hepato-Gastroenterogy Unit, Croix-Rousse Hospital, Hospices Civils de Lyon, Lyon, France
- Labex DEVweCAN, Lyon, France
| | - Ourania Andrisani
- Department of Basic Medical Sciences and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN
| | - David Durantel
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- Labex DEVweCAN, Lyon, France
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Diab A, Foca A, Zoulim F, Durantel D, Andrisani O. The diverse functions of the hepatitis B core/capsid protein (HBc) in the viral life cycle: Implications for the development of HBc-targeting antivirals. Antiviral Res 2017; 149:211-220. [PMID: 29183719 DOI: 10.1016/j.antiviral.2017.11.015] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/08/2017] [Accepted: 11/17/2017] [Indexed: 12/14/2022]
Abstract
Virally encoded proteins have evolved to perform multiple functions, and the core protein (HBc) of the hepatitis B virus (HBV) is a perfect example. While HBc is the structural component of the viral nucleocapsid, additional novel functions for the nucleus-localized HBc have recently been described. These results extend for HBc, beyond its structural role, a regulatory function in the viral life cycle and potentially a role in pathogenesis. In this article, we review the diverse roles of HBc in HBV replication and pathogenesis, emphasizing how the unique structure of this protein is key to its various functions. We focus in particular on recent advances in understanding the significance of HBc phosphorylations, its interaction with host proteins and the role of HBc in regulating the transcription of host genes. We also briefly allude to the emerging niche for new direct-acting antivirals targeting HBc, known as Core (protein) Allosteric Modulators (CAMs).
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Affiliation(s)
- Ahmed Diab
- Department of Basic Medical Sciences and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA; INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), UMR_S1052, UCBL, 69008, Lyon, France
| | - Adrien Foca
- INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), UMR_S1052, UCBL, 69008, Lyon, France
| | - Fabien Zoulim
- INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), UMR_S1052, UCBL, 69008, Lyon, France; Hepato-Gastroenterology Unit, Croix-Rousse Hospital, Hospices Civils de Lyon (HCL), 69002, Lyon, France; Labex DEVweCAN, 69008, Lyon, France
| | - David Durantel
- INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), UMR_S1052, UCBL, 69008, Lyon, France; Hepato-Gastroenterology Unit, Croix-Rousse Hospital, Hospices Civils de Lyon (HCL), 69002, Lyon, France.
| | - Ourania Andrisani
- Department of Basic Medical Sciences and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA.
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40
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Patel N, White SJ, Thompson RF, Bingham R, Weiß EU, Maskell DP, Zlotnick A, Dykeman E, Tuma R, Twarock R, Ranson NA, Stockley PG. HBV RNA pre-genome encodes specific motifs that mediate interactions with the viral core protein that promote nucleocapsid assembly. Nat Microbiol 2017; 2:17098. [PMID: 28628133 PMCID: PMC5495169 DOI: 10.1038/nmicrobiol.2017.98] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 05/17/2017] [Indexed: 12/20/2022]
Abstract
Formation of the hepatitis B virus nucleocapsid is an essential step in the viral lifecycle, but its assembly is not fully understood. We report the discovery of sequence-specific interactions between the viral pre-genome and the hepatitis B core protein that play roles in defining the nucleocapsid assembly pathway. Using RNA SELEX and bioinformatics, we identified multiple regions in the pre-genomic RNA with high affinity for core protein dimers. These RNAs form stem-loops with a conserved loop motif that trigger sequence-specific assembly of virus-like particles (VLPs) at much higher fidelity and yield than in the absence of RNA. The RNA oligos do not interact with preformed RNA-free VLPs, so their effects must occur during particle assembly. Asymmetric cryo-electron microscopy reconstruction of the T = 4 VLPs assembled in the presence of one of the RNAs reveals a unique internal feature connected to the main core protein shell via lobes of density. Biophysical assays suggest that this is a complex involving several RNA oligos interacting with the C-terminal arginine-rich domains of core protein. These core protein-RNA contacts may play one or more roles in regulating the organization of the pre-genome during nucleocapsid assembly, facilitating subsequent reverse transcription and acting as a nucleation complex for nucleocapsid assembly.
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Affiliation(s)
- Nikesh Patel
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Simon J White
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Rebecca F Thompson
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Richard Bingham
- Departments of Biology and Mathematics & York Centre for Complex Systems Analysis, University of York, York, YO10 5DD, UK
| | - Eva U Weiß
- Departments of Biology and Mathematics & York Centre for Complex Systems Analysis, University of York, York, YO10 5DD, UK
| | - Daniel P Maskell
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Adam Zlotnick
- Department of Molecular & Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Eric Dykeman
- Departments of Biology and Mathematics & York Centre for Complex Systems Analysis, University of York, York, YO10 5DD, UK
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Reidun Twarock
- Departments of Biology and Mathematics & York Centre for Complex Systems Analysis, University of York, York, YO10 5DD, UK
| | - Neil A Ranson
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Peter G Stockley
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
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41
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Deng W, Zhang X, Ma Z, Lin Y, Lu M. MicroRNA-125b-5p mediates post-transcriptional regulation of hepatitis B virus replication via the LIN28B/let-7 axis. RNA Biol 2017; 14:1389-1398. [PMID: 28267418 DOI: 10.1080/15476286.2017.1293770] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
MicroRNAs (miRNAs) are able to modulate hepatitis B virus (HBV) replication and play an important role in the pathogenesis of HBV infection. Recently, we have identified that serum miR-125b-5p levels correlated with HBV DNA levels and liver necroinflammation. In the present study, we addressed how miR-125b-5p regulated HBV replication at the different steps, inclduing viral transcription, assembly, and virion production and investigated the underlying mechanisms. We found that miR-125b-5p overexpression increased HBV replication without altering HBV transcription. This is the first demonstration of post-transcriptional miRNA regulation of HBV replication. In contrast, transfection of miR-125b-5p inhibitor resulted in downregulation of HBV replication in hepatoma cells. Further, miR-125b-5p inhibited the phosphorylation of retinoblastoma protein and blocked cell cycle progression at the G1/S phase in hepatoma cell lines. Our results indicate that certain miRNAs are able to arrest the cell cycle at G1 phase and may increase HBV replication. RNA sequencing revealed several liver-specific metabolic pathways regulated by miR-125b-5p, which was also found to suppress LIN28B and induce let-7 family members. Additional data demonstrated that miR-125b-5p targeted the LIN28B/let-7 axis to stimulate HBV replication at a post-transcriptional step.
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Affiliation(s)
- Wanyu Deng
- a Institute of Virology, University Hospital Essen, University of Duisburg-Essen , Essen , Germany.,b College of Life Science, Shangrao Normal University , Shangrao , China
| | - Xiaoyong Zhang
- a Institute of Virology, University Hospital Essen, University of Duisburg-Essen , Essen , Germany
| | - Zhiyong Ma
- a Institute of Virology, University Hospital Essen, University of Duisburg-Essen , Essen , Germany
| | - Yong Lin
- a Institute of Virology, University Hospital Essen, University of Duisburg-Essen , Essen , Germany
| | - Mengji Lu
- a Institute of Virology, University Hospital Essen, University of Duisburg-Essen , Essen , Germany
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42
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A screening assay for the identification of host cell requirements and antiviral targets for hepatitis D virus infection. Antiviral Res 2017; 141:116-123. [PMID: 28223128 DOI: 10.1016/j.antiviral.2017.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 02/15/2017] [Accepted: 02/17/2017] [Indexed: 01/10/2023]
Abstract
Hepatitis delta virus (HDV) is a minimalistic satellite virus of hepatitis B virus (HBV). HBV/HDV co-infection, i.e. "hepatitis D", is the most severe form of viral hepatitis. No effective therapy for HDV infection is available partly due to the fact that HDV is a highly host-dependent virus devoid of any potentially drugable enzyme encoded in its small genome. In this study we present a semi-automated method to evaluate HDV infection and replication under the influence of different drugs. We utilized a Huh-7/hNTCP cell culture based system in a 96-well plate format, an automated microscope and image acquisition as well as analysis with the CellProfiler software to quantify the impact of these drugs on HDV infection. For validation, three groups of potential anti-HDV agents were evaluated: To target ribozyme activity of HDV RNA, we screened ribozyme inhibitors but only observed marked toxicity. Testing innate antiviral mediators showed that interferons alpha-2a and beta-1a had a specific inhibitory effect on HDV infection. Finally, we screened a library of 160 human kinase inhibitors covering all parts of the human kinome. Overall, only inhibitors targeting the tyrosine kinase-like group had significant average anti-HDV activity. Looking at individual substances, kenpaullone, a GSK-3β and Cdk inhibitor, had the highest selective index of 3.44. Thus, we provide a potentially useful tool to screen for substances with anti-HDV activity and novel insights into interactions between HDV replication and the human kinome.
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Pumpens P, Grens E. The true story and advantages of the famous Hepatitis B virus core particles: Outlook 2016. Mol Biol 2016. [DOI: 10.1134/s0026893316040099] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Tanaka T, Okuyama-Dobashi K, Murakami S, Chen W, Okamoto T, Ueda K, Hosoya T, Matsuura Y, Ryo A, Tanaka Y, Hagiwara M, Moriishi K. Inhibitory effect of CDK9 inhibitor FIT-039 on hepatitis B virus propagation. Antiviral Res 2016; 133:156-64. [PMID: 27515132 DOI: 10.1016/j.antiviral.2016.08.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 08/04/2016] [Accepted: 08/07/2016] [Indexed: 02/07/2023]
Abstract
Current therapies for hepatitis B virus (HBV) cannot completely eliminate the HBV genome because of the stable population of covalently closed circular DNA (cccDNA) and so on. FIT-039, which is a cyclin-dependent kinase (CDK) 9 inhibitor, is known to suppress the replication of several DNA viruses including HSV, HPV and human adenovirus. In this study, we investigated the antiviral effect of FIT-039 on HBV infection. HepG2 cells expressing human sodium taurocholate cotransporting polypeptide (HepG2/NTCP cells) were infected with HBV in the presence of FIT-039. FIT-039 dose-dependently reduced intracellular viral RNA, nucleocapsid-associated viral DNA, and supernatant viral antigens without cytotoxicity in the infected cells (IC50 = 0.33 μM, CC50 > 50 μM). The antiviral activity of FIT-039 was prominent at an early phase of viral infection, although the compound did not inhibit preS1-binding to HepG2/NTCP cells. FIT-039 reduced cccDNA in HBV-replicating or HBV-infected cells. Furthermore, the antiviral activity of entecavir was significantly enhanced by the combination with FIT-039 in the chimeric mice having human hepatocytes infected with HBV. None of the mice had significant drug-related body weight or serum human-albumin concentration changes. These data suggest that CDK9 inhibitor FIT-039 is a promising antiviral candidate for HBV infection.
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Affiliation(s)
- Tomohisa Tanaka
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Kaori Okuyama-Dobashi
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Shuko Murakami
- Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Wenjia Chen
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Toru Okamoto
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Keiji Ueda
- Division of Virology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Takamitsu Hosoya
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yoshiharu Matsuura
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Akihide Ryo
- Department of Molecular Biodefense Research, Yokohama City University Graduate School of Medicine, Kanagawa 236-0004, Japan
| | - Yasuhito Tanaka
- Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Masatoshi Hagiwara
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Kohji Moriishi
- Department of Microbiology, Graduate School of Medical Science, University of Yamanashi, Yamanashi 409-3898, Japan.
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Abstract
Hepatitis B virus is one of the smallest human pathogens, encoded by a 3,200-bp genome with only four open reading frames. Yet the virus shows a remarkable diversity in structural features, often with the same proteins adopting several conformations. In part, this is the parsimony of viruses, where a minimal number of proteins perform a wide variety of functions. However, a more important theme is that weak interactions between components as well as components with multiple conformations that have similar stabilities lead to a highly dynamic system. In hepatitis B virus, this is manifested as a virion where the envelope proteins have multiple structures, the envelope-capsid interaction is irregular, and the capsid is a dynamic compartment that actively participates in metabolism of the encapsidated genome and carries regulated signals for intracellular trafficking.
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Affiliation(s)
| | - Adam Zlotnick
- Department of Molecular and Cellular Biology, Indiana University, Bloomington, Indiana 47405;
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Lamontagne RJ, Bagga S, Bouchard MJ. Hepatitis B virus molecular biology and pathogenesis. HEPATOMA RESEARCH 2016; 2:163-186. [PMID: 28042609 PMCID: PMC5198785 DOI: 10.20517/2394-5079.2016.05] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
As obligate intracellular parasites, viruses need a host cell to provide a milieu favorable to viral replication. Consequently, viruses often adopt mechanisms to subvert host cellular signaling processes. While beneficial for the viral replication cycle, virus-induced deregulation of host cellular signaling processes can be detrimental to host cell physiology and can lead to virus-associated pathogenesis, including, for oncogenic viruses, cell transformation and cancer progression. Included among these oncogenic viruses is the hepatitis B virus (HBV). Despite the availability of an HBV vaccine, 350-500 million people worldwide are chronically infected with HBV, and a significant number of these chronically infected individuals will develop hepatocellular carcinoma (HCC). Epidemiological studies indicate that chronic infection with HBV is the leading risk factor for the development of HCC. Globally, HCC is the second highest cause of cancer-associated deaths, underscoring the need for understanding mechanisms that regulate HBV replication and the development of HBV-associated HCC. HBV is the prototype member of the Hepadnaviridae family; members of this family of viruses have a narrow host range and predominately infect hepatocytes in their respective hosts. The extremely small and compact hepadnaviral genome, the unique arrangement of open reading frames, and a replication strategy utilizing reverse transcription of an RNA intermediate to generate the DNA genome are distinguishing features of the Hepadnaviridae. In this review, we provide a comprehensive description of HBV biology, summarize the model systems used for studying HBV infections, and highlight potential mechanisms that link a chronic HBV-infection to the development of HCC. For example, the HBV X protein (HBx), a key regulatory HBV protein that is important for HBV replication, is thought to play a cofactor role in the development of HBV-induced HCC, and we highlight the functions of HBx that may contribute to the development of HBV-associated HCC.
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Affiliation(s)
- R. Jason Lamontagne
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
- The Wistar Institute, Philadelphia, PA 19104, USA
| | - Sumedha Bagga
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
| | - Michael J. Bouchard
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
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Cell-Free Hepatitis B Virus Capsid Assembly Dependent on the Core Protein C-Terminal Domain and Regulated by Phosphorylation. J Virol 2016; 90:5830-5844. [PMID: 27076641 DOI: 10.1128/jvi.00394-16] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/07/2016] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Multiple subunits of the hepatitis B virus (HBV) core protein (HBc) assemble into an icosahedral capsid that packages the viral pregenomic RNA (pgRNA). The N-terminal domain (NTD) of HBc is sufficient for capsid assembly, in the absence of pgRNA or any other viral or host factors, under conditions of high HBc and/or salt concentrations. The C-terminal domain (CTD) is deemed dispensable for capsid assembly although it is essential for pgRNA packaging. We report here that HBc expressed in a mammalian cell lysate, rabbit reticulocyte lysate (RRL), was able to assemble into capsids when (low-nanomolar) HBc concentrations mimicked those achieved under conditions of viral replication in vivo and were far below those used previously for capsid assembly in vitro Furthermore, at physiologically low HBc concentrations in RRL, the NTD was insufficient for capsid assembly and the CTD was also required. The CTD likely facilitated assembly under these conditions via RNA binding and protein-protein interactions. Moreover, the CTD underwent phosphorylation and dephosphorylation events in RRL similar to those seen in vivo which regulated capsid assembly. Importantly, the NTD alone also failed to accumulate in mammalian cells, likely resulting from its failure to assemble efficiently. Coexpression of the full-length HBc rescued NTD assembly in RRL as well as NTD expression and assembly in mammalian cells, resulting in the formation of mosaic capsids containing both full-length HBc and the NTD. These results have important implications for HBV assembly during replication and provide a facile cell-free system to study capsid assembly under physiologically relevant conditions, including its modulation by host factors. IMPORTANCE Hepatitis B virus (HBV) is an important global human pathogen and the main cause of liver cancer worldwide. An essential component of HBV is the spherical capsid composed of multiple copies of a single protein, the core protein (HBc). We have developed a mammalian cell-free system in which HBc is expressed at physiological (low) concentrations and assembles into capsids under near-physiological conditions. In this cell-free system, as in mammalian cells, capsid assembly depends on the C-terminal domain (CTD) of HBc, in contrast to other assembly systems in which HBc assembles into capsids independently of the CTD under conditions of nonphysiological protein and salt concentrations. Furthermore, the phosphorylation state of the CTD regulates capsid assembly and RNA encapsidation in the cell-free system in a manner similar to that seen in mammalian cells. This system will facilitate detailed studies on capsid assembly and RNA encapsidation under physiological conditions and identification of antiviral agents that target HBc.
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Lamontagne J, Mell JC, Bouchard MJ. Transcriptome-Wide Analysis of Hepatitis B Virus-Mediated Changes to Normal Hepatocyte Gene Expression. PLoS Pathog 2016; 12:e1005438. [PMID: 26891448 PMCID: PMC4758756 DOI: 10.1371/journal.ppat.1005438] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 01/13/2016] [Indexed: 12/11/2022] Open
Abstract
Globally, a chronic hepatitis B virus (HBV) infection remains the leading cause of primary liver cancer. The mechanisms leading to the development of HBV-associated liver cancer remain incompletely understood. In part, this is because studies have been limited by the lack of effective model systems that are both readily available and mimic the cellular environment of a normal hepatocyte. Additionally, many studies have focused on single, specific factors or pathways that may be affected by HBV, without addressing cell physiology as a whole. Here, we apply RNA-seq technology to investigate transcriptome-wide, HBV-mediated changes in gene expression to identify single factors and pathways as well as networks of genes and pathways that are affected in the context of HBV replication. Importantly, these studies were conducted in an ex vivo model of cultured primary hepatocytes, allowing for the transcriptomic characterization of this model system and an investigation of early HBV-mediated effects in a biologically relevant context. We analyzed differential gene expression within the context of time-mediated gene-expression changes and show that in the context of HBV replication a number of genes and cellular pathways are altered, including those associated with metabolism, cell cycle regulation, and lipid biosynthesis. Multiple analysis pipelines, as well as qRT-PCR and an independent, replicate RNA-seq analysis, were used to identify and confirm differentially expressed genes. HBV-mediated alterations to the transcriptome that we identified likely represent early changes to hepatocytes following an HBV infection, suggesting potential targets for early therapeutic intervention. Overall, these studies have produced a valuable resource that can be used to expand our understanding of the complex network of host-virus interactions and the impact of HBV-mediated changes to normal hepatocyte physiology on viral replication.
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Affiliation(s)
- Jason Lamontagne
- Graduate Program in Microbiology and Immunology, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Joshua C. Mell
- Department of Microbiology and Immunology, Center for Genomic Sciences, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Michael J. Bouchard
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
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Selzer L, Zlotnick A. Assembly and Release of Hepatitis B Virus. Cold Spring Harb Perspect Med 2015; 5:cshperspect.a021394. [PMID: 26552701 DOI: 10.1101/cshperspect.a021394] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The hepatitis B virus (HBV) core protein is a dynamic and versatile protein that directs many viral processes. During capsid assembly, core protein allosteric changes ensure efficient formation of a stable capsid that assembles while packaging viral RNA-polymerase complex. Reverse transcription of the RNA genome as well as transport of the capsid to multiple cellular compartments are directed by dynamic phosphorylation and structural changes of core protein. Subsequently, interactions of the capsid with the surface proteins and/or host proteins trigger envelopment and release of the viral capsids or the transport to the nucleus. Held together by many weak protein-protein interactions, the viral capsid is an extraordinary metastable machine that is stable enough to persist in the cellular and extracellular environment but dissociates to allow release of the viral genome at the right time during infection.
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Affiliation(s)
- Lisa Selzer
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405
| | - Adam Zlotnick
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405
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Alteration of Mature Nucleocapsid and Enhancement of Covalently Closed Circular DNA Formation by Hepatitis B Virus Core Mutants Defective in Complete-Virion Formation. J Virol 2015. [PMID: 26202253 DOI: 10.1128/jvi.01481-15] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Assembly of hepatitis B virus (HBV) begins with packaging of the pregenomic RNA (pgRNA) into immature nucleocapsids (NC), which are converted to mature NCs containing the genomic relaxed circular (RC) DNA as a result of reverse transcription. Mature NCs have two alternative fates: (i) envelopment by viral envelope proteins, leading to secretion extracellularly as virions, or (ii) disassembly (uncoating) to deliver their RC DNA content into the host cell nucleus for conversion to the covalently closed circular (CCC) DNA, the template for viral transcription. How these two alternative fates are regulated remains to be better understood. The NC shell is composed of multiple copies of a single viral protein, the HBV core (HBc) protein. HBc mutations located on the surface of NC have been identified that allow NC maturation but block its envelopment. The potential effects of some of these mutations on NC uncoating and CCC DNA formation have been analyzed by transfecting HBV replication constructs into hepatoma cells. All envelopment-defective HBc mutations tested were competent for CCC DNA formation, indicating that core functions in envelopment and uncoating/nuclear delivery of RC DNA were genetically separable. Some of the envelopment-defective HBc mutations were found to alter specifically the integrity of mature, but not immature, NCs such that RC DNA became susceptible to nuclease digestion. Furthermore, CCC DNA formation could be enhanced by NC surface mutations that did or did not significantly affect mature NC integrity, indicating that the NC surface residues may be closely involved in NC uncoating and/or nuclear delivery of RC DNA. IMPORTANCE Hepatitis B virus (HBV) infection is a major health issue worldwide. HBV assembly begins with the packaging into immature nucleocapsids (NCs) of a viral RNA pregenome, which is converted to the DNA genome in mature NCs. Mature NCs are then selected for envelopment and secretion as complete-virion particles or, alternatively, can deliver their DNA to the host cell nucleus to maintain the viral genome as nuclear episomes, which are the basis for virus persistence. Previous studies have identified mutations on the capsid surface that selectively block NC envelopment without affecting NC maturation. We have now discovered that some of the same mutations result in preferential alteration of mature NCs and increased viral nuclear episomes. These findings provide important new insights into the regulation of the two alternative fates of mature NCs and suggest new ways to perturb viral persistence by manipulating levels of viral nuclear episomes.
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