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Tillmanns J, Kicuntod J, Lösing J, Marschall M. 'Getting Better'-Is It a Feasible Strategy of Broad Pan-Antiherpesviral Drug Targeting by Using the Nuclear Egress-Directed Mechanism? Int J Mol Sci 2024; 25:2823. [PMID: 38474070 DOI: 10.3390/ijms25052823] [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: 01/28/2024] [Revised: 02/24/2024] [Accepted: 02/26/2024] [Indexed: 03/14/2024] Open
Abstract
The herpesviral nuclear egress represents an essential step of viral replication efficiency in host cells, as it defines the nucleocytoplasmic release of viral capsids. Due to the size limitation of the nuclear pores, viral nuclear capsids are unable to traverse the nuclear envelope without a destabilization of this natural host-specific barrier. To this end, herpesviruses evolved the regulatory nuclear egress complex (NEC), composed of a heterodimer unit of two conserved viral NEC proteins (core NEC) and a large-size extension of this complex including various viral and cellular NEC-associated proteins (multicomponent NEC). Notably, the NEC harbors the pronounced ability to oligomerize (core NEC hexamers and lattices), to multimerize into higher-order complexes, and, ultimately, to closely interact with the migrating nuclear capsids. Moreover, most, if not all, of these NEC proteins comprise regulatory modifications by phosphorylation, so that the responsible kinases, and additional enzymatic activities, are part of the multicomponent NEC. This sophisticated basis of NEC-specific structural and functional interactions offers a variety of different modes of antiviral interference by pharmacological or nonconventional inhibitors. Since the multifaceted combination of NEC activities represents a highly conserved key regulatory stage of herpesviral replication, it may provide a unique opportunity towards a broad, pan-antiherpesviral mechanism of drug targeting. This review presents an update on chances, challenges, and current achievements in the development of NEC-directed antiherpesviral strategies.
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Affiliation(s)
- Julia Tillmanns
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Jintawee Kicuntod
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Josephine Lösing
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
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Sucharita S, Krishnagopal A, van Drunen Littel-van den Hurk S. Comprehensive Analysis of the Tegument Proteins Involved in Capsid Transport and Virion Morphogenesis of Alpha, Beta and Gamma Herpesviruses. Viruses 2023; 15:2058. [PMID: 37896835 PMCID: PMC10611259 DOI: 10.3390/v15102058] [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: 08/10/2023] [Revised: 09/21/2023] [Accepted: 09/21/2023] [Indexed: 10/29/2023] Open
Abstract
Herpesviruses are enveloped and have an amorphous protein layer surrounding the capsid, which is termed the tegument. Tegument proteins perform critical functions throughout the viral life cycle. This review provides a comprehensive and comparative analysis of the roles of specific tegument proteins in capsid transport and virion morphogenesis of selected, well-studied prototypes of each of the three subfamilies of Herpesviridae i.e., human herpesvirus-1/herpes simplex virus-1 (Alphaherpesvirinae), human herpesvirus-5/cytomegalovirus (Betaherpesvirinae) and human herpesvirus -8/Kaposi's sarcomavirus (Gammaherpesvirinae). Most of the current knowledge is based on alpha herpesviruses, in particular HSV-1. While some tegument proteins are released into the cytoplasm after virus entry, several tegument proteins remain associated with the capsid and are responsible for transport to and docking at the nucleus. After replication and capsid formation, the capsid is enveloped at the nuclear membrane, which is referred to as primary envelopment, followed by de-envelopment and release into the cytoplasm. This requires involvement of at least three tegument proteins. Subsequently, multiple interactions between tegument proteins and capsid proteins, other tegument proteins and glycoproteins are required for assembly of the virus particles and envelopment at the Golgi, with certain tegument proteins acting as the central hub for these interactions. Some redundancy in these interactions ensures appropriate morphogenesis.
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Affiliation(s)
- Soumya Sucharita
- Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; (S.S.); (A.K.)
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, SK S7N 5E3, Canada
| | - Akshaya Krishnagopal
- Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; (S.S.); (A.K.)
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, SK S7N 5E3, Canada
| | - Sylvia van Drunen Littel-van den Hurk
- Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; (S.S.); (A.K.)
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, SK S7N 5E3, Canada
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Tillmanns J, Häge S, Borst EM, Wardin J, Eickhoff J, Klebl B, Wagner S, Wangen C, Hahn F, Socher E, Marschall M. Assessment of Covalently Binding Warhead Compounds in the Validation of the Cytomegalovirus Nuclear Egress Complex as an Antiviral Target. Cells 2023; 12:cells12081162. [PMID: 37190072 DOI: 10.3390/cells12081162] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 04/06/2023] [Accepted: 04/06/2023] [Indexed: 05/17/2023] Open
Abstract
Herpesviral nuclear egress is a regulated process of viral capsid nucleocytoplasmic release. Due to the large capsid size, a regular transport via the nuclear pores is unfeasible, so that a multistage-regulated export pathway through the nuclear lamina and both leaflets of the nuclear membrane has evolved. This process involves regulatory proteins, which support the local distortion of the nuclear envelope. For human cytomegalovirus (HCMV), the nuclear egress complex (NEC) is determined by the pUL50-pUL53 core that initiates multicomponent assembly with NEC-associated proteins and capsids. The transmembrane NEC protein pUL50 serves as a multi-interacting determinant that recruits regulatory proteins by direct and indirect contacts. The nucleoplasmic core NEC component pUL53 is strictly associated with pUL50 in a structurally defined hook-into-groove complex and is considered as the potential capsid-binding factor. Recently, we validated the concept of blocking the pUL50-pUL53 interaction by small molecules as well as cell-penetrating peptides or an overexpression of hook-like constructs, which can lead to a pronounced degree of antiviral activity. In this study, we extended this strategy by utilizing covalently binding warhead compounds, originally designed as binders of distinct cysteine residues in target proteins, such as regulatory kinases. Here, we addressed the possibility that warheads may likewise target viral NEC proteins, building on our previous crystallization-based structural analyses that revealed distinct cysteine residues in positions exposed from the hook-into-groove binding surface. To this end, the antiviral and NEC-binding properties of a selection of 21 warhead compounds were investigated. The combined findings are as follows: (i) warhead compounds exhibited a pronounced anti-HCMV potential in cell-culture-based infection models; (ii) computational analysis of NEC primary sequences and 3D structures revealed cysteine residues exposed to the hook-into-groove interaction surface; (iii) several of the active hit compounds exhibited NEC-blocking activity, as shown at the single-cell level by confocal imaging; (iv) the clinically approved warhead drug ibrutinib exerted a strong inhibitory impact on the pUL50-pUL53 core NEC interaction, as demonstrated by the NanoBiT assay system; and (v) the generation of recombinant HCMV ∆UL50-ΣUL53, allowing the assessment of viral replication under conditional expression of the viral core NEC proteins, was used for characterizing viral replication and a mechanistic evaluation of ibrutinib antiviral efficacy. Combined, the results point to a rate-limiting importance of the HCMV core NEC for viral replication and to the option of exploiting this determinant by the targeting of covalently NEC-binding warhead compounds.
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Affiliation(s)
- Julia Tillmanns
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Sigrun Häge
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Eva Maria Borst
- Institute of Virology, Hannover Medical School, 30625 Hannover, Germany
| | - Julia Wardin
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Jan Eickhoff
- Lead Discovery Center GmbH (LDC), 44227 Dortmund, Germany
| | - Bert Klebl
- Lead Discovery Center GmbH (LDC), 44227 Dortmund, Germany
- The Norwegian College of Fishery Science UiT, The Arctic University of Norway, 9037 Tromsø, Norway
| | - Sabrina Wagner
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Christina Wangen
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Friedrich Hahn
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Eileen Socher
- Institute of Anatomy, Functional and Clinical Anatomy, FAU, 91054 Erlangen, Germany
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
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Kicuntod J, Häge S, Lösing J, Kopar S, Muller YA, Marschall M. An antiviral targeting strategy based on the inducible interference with cytomegalovirus nuclear egress complex. Antiviral Res 2023; 212:105557. [PMID: 36796541 DOI: 10.1016/j.antiviral.2023.105557] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/16/2023]
Abstract
The nucleocytoplasmic capsid egress of herpesviruses like the human cytomegalovirus (HCMV) is based on a uniquely regulated process. The core nuclear egress complex (NEC) of HCMV, represented by the pUL50-pUL53 heterodimer, is able to oligomerize and thus to build hexameric lattices. Recently, we and others validated the NEC as a novel target for antiviral strategies. So far, the experimental targeting approaches included the development of NEC-directed small molecules, cell-penetrating peptides and NEC-directed mutagenesis. Our postulate states that an interference with the hook-into-groove interaction of pUL50-pUL53 prevents NEC formation and strictly limits viral replication efficiency. Here, we provide an experimental proof-of-concept of the antiviral strategy: the inducible intracellular expression of a NLS-Hook-GFP construct exerted a pronounced level of antiviral activity. The data provide evidence for the following points: (i) generation of a primary fibroblast population with inducible NLS-Hook-GFP expression showed nuclear localization of the construct, (ii) interaction between NLS-Hook-GFP and the viral core NEC was found specific for cytomegaloviruses but not for other herpesviruses, (iii) construct overexpression exerted a strong antiviral activity against three strains of HCMV, (iv) confocal imaging demonstrated the interference with NEC nuclear rim formation in HCMV-infected cells, and (v) quantitative nuclear egress assay confirmed the block of viral nucleocytoplasmic transition and, consequently, an inhibitory effect onto viral cytoplasmic virion assembly complex (cVAC). Combined, data confirmed that the specific interference with protein-protein interaction of the HCMV core NEC represents an efficient antiviral targeting strategy.
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Affiliation(s)
- Jintawee Kicuntod
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Sigrun Häge
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Josephine Lösing
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Serli Kopar
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Yves A Muller
- Division of Biotechnology, Department of Biology, FAU, Erlangen, Germany.
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
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Ponnuraj N, Akbar H, Arrington JV, Spatz SJ, Nagarajan B, Desai UR, Jarosinski KW. The alphaherpesvirus conserved pUS10 is important for natural infection and its expression is regulated by the conserved Herpesviridae protein kinase (CHPK). PLoS Pathog 2023; 19:e1010959. [PMID: 36749787 PMCID: PMC9946255 DOI: 10.1371/journal.ppat.1010959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 02/22/2023] [Accepted: 01/30/2023] [Indexed: 02/08/2023] Open
Abstract
Conserved Herpesviridae protein kinases (CHPK) are conserved among all members of the Herpesviridae. Herpesviruses lacking CHPK propagate in cell culture at varying degrees, depending on the virus and cell culture system. CHPK is dispensable for Marek's disease herpesvirus (MDV) replication in cell culture and experimental infection in chickens; however, CHPK-particularly its kinase activity-is essential for horizontal transmission in chickens, also known as natural infection. To address the importance of CHPK during natural infection in chickens, we used liquid chromatography-tandem mass spectrometry (LC-MS/MS) based proteomics of samples collected from live chickens. Comparing modification of viral proteins in feather follicle epithelial (FFE) cells infected with wildtype or a CHPK-null virus, we identified the US10 protein (pUS10) as a potential target for CHPK in vivo. When expression of pUS10 was evaluated in cell culture and in FFE skin cells during in vivo infection, pUS10 was severely reduced or abrogated in cells infected with CHPK mutant or CHPK-null viruses, respectively, indicating a potential role for pUS10 in transmission. To test this hypothesis, US10 was deleted from the MDV genome, and the reconstituted virus was tested for replication, horizontal transmission, and disease induction. Our results showed that removal of US10 had no effect on the ability of MDV to transmit in experimentally infected chickens, but disease induction in naturally infected chickens was significantly reduced. These results show CHPK is necessary for pUS10 expression both in cell culture and in the host, and pUS10 is important for disease induction during natural infection.
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Affiliation(s)
- Nagendraprabhu Ponnuraj
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Haji Akbar
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Justine V. Arrington
- Protein Sciences Facility, Roy J. Carver Biotechnology Center, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Stephen J. Spatz
- US National Poultry Research Laboratory, Agricultural Research Service, United States Department of Agriculture, Athens, Georgia, United States of America
| | - Balaji Nagarajan
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Umesh R. Desai
- Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Keith W. Jarosinski
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
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Turner DL, Mathias RA. The human cytomegalovirus decathlon: Ten critical replication events provide opportunities for restriction. Front Cell Dev Biol 2022; 10:1053139. [PMID: 36506089 PMCID: PMC9732275 DOI: 10.3389/fcell.2022.1053139] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 11/10/2022] [Indexed: 11/27/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a ubiquitous human pathogen that can cause severe disease in immunocompromised individuals, transplant recipients, and to the developing foetus during pregnancy. There is no protective vaccine currently available, and with only a limited number of antiviral drug options, resistant strains are constantly emerging. Successful completion of HCMV replication is an elegant feat from a molecular perspective, with both host and viral processes required at various stages. Remarkably, HCMV and other herpesviruses have protracted replication cycles, large genomes, complex virion structure and complicated nuclear and cytoplasmic replication events. In this review, we outline the 10 essential stages the virus must navigate to successfully complete replication. As each individual event along the replication continuum poses as a potential barrier for restriction, these essential checkpoints represent potential targets for antiviral development.
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Affiliation(s)
- Declan L. Turner
- Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Rommel A. Mathias
- Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia,Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC, Australia,*Correspondence: Rommel A. Mathias,
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Stiekema M, Houben F, Verheyen F, Borgers M, Menzel J, Meschkat M, van Zandvoort MAMJ, Ramaekers FCS, Broers JLV. The Role of Lamins in the Nucleoplasmic Reticulum, a Pleiomorphic Organelle That Enhances Nucleo-Cytoplasmic Interplay. Front Cell Dev Biol 2022; 10:914286. [PMID: 35784476 PMCID: PMC9243388 DOI: 10.3389/fcell.2022.914286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/24/2022] [Indexed: 12/15/2022] Open
Abstract
Invaginations of the nuclear membrane occur in different shapes, sizes, and compositions. Part of these pleiomorphic invaginations make up the nucleoplasmic reticulum (NR), while others are merely nuclear folds. We define the NR as tubular invaginations consisting of either both the inner and outer nuclear membrane, or only the inner nuclear membrane. Specifically, invaginations of both the inner and outer nuclear membrane are also called type II NR, while those of only the inner nuclear membrane are defined as type I NR. The formation and structure of the NR is determined by proteins associated to the nuclear membrane, which induce a high membrane curvature leading to tubular invaginations. Here we review and discuss the current knowledge of nuclear invaginations and the NR in particular. An increase in tubular invaginations of the nuclear envelope is associated with several pathologies, such as laminopathies, cancer, (reversible) heart failure, and Alzheimer’s disease. Furthermore, viruses can induce both type I and II NR. In laminopathies, the amount of A-type lamins throughout the nucleus is generally decreased or the organization of lamins or lamin-associated proteins is disturbed. Also, lamin overexpression or modulation of lamin farnesylation status impacts NR formation, confirming the importance of lamin processing in NR formation. Virus infections reorganize the nuclear lamina via (de)phosphorylation of lamins, leading to an uneven thickness of the nuclear lamina and in turn lobulation of the nuclear membrane and the formation of invaginations of the inner nuclear membrane. Since most studies on the NR have been performed with cell cultures, we present additional proof for the existence of these structures in vivo, focusing on a variety of differentiated cardiovascular and hematopoietic cells. Furthermore, we substantiate the knowledge of the lamin composition of the NR by super-resolution images of the lamin A/C and B1 organization. Finally, we further highlight the essential role of lamins in NR formation by demonstrating that (over)expression of lamins can induce aberrant NR structures.
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Affiliation(s)
- Merel Stiekema
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
- GROW-School for Oncology and Reproduction, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Frederik Houben
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
- Department of Healthcare, PXL University College, Hasselt, Belgium
| | - Fons Verheyen
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Marcel Borgers
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | | | | | - Marc A. M. J. van Zandvoort
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
- GROW-School for Oncology and Reproduction, Maastricht University Medical Centre, Maastricht, Netherlands
- CARIM-School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, Netherlands
- Institute for Molecular Cardiovascular Research IMCAR, RWTH Aachen University, Aachen, Germany
| | - Frans C. S. Ramaekers
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
- GROW-School for Oncology and Reproduction, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Jos L. V. Broers
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
- GROW-School for Oncology and Reproduction, Maastricht University Medical Centre, Maastricht, Netherlands
- CARIM-School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, Netherlands
- *Correspondence: Jos L. V. Broers,
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‘Come Together’—The Regulatory Interaction of Herpesviral Nuclear Egress Proteins Comprises both Essential and Accessory Functions. Cells 2022; 11:cells11111837. [PMID: 35681532 PMCID: PMC9180862 DOI: 10.3390/cells11111837] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/31/2022] [Accepted: 06/01/2022] [Indexed: 02/01/2023] Open
Abstract
Herpesviral nuclear egress is a fine-tuned regulatory process that defines the nucleocytoplasmic release of viral capsids. Nuclear capsids are unable to traverse via nuclear pores due to the fact of their large size; therefore, herpesviruses evolved to develop a vesicular transport pathway mediating the transition across the two leaflets of the nuclear membrane. The entire process involves a number of regulatory proteins, which support the local distortion of the nuclear envelope. In the case of the prototype species of β-Herpesvirinae, the human cytomegalovirus (HCMV), the nuclear egress complex (NEC) is determined by the core proteins pUL50 and pUL53 that oligomerize, form capsid docking lattices and mediate multicomponent assembly with NEC-associated viral and cellular proteins. The NEC-binding principle is based on the hook-into-groove interaction through an N-terminal hook-like pUL53 protrusion that embraces an α-helical pUL50 binding groove. Thus far, the function and characteristics of herpesviral core NECs have been well studied and point to the groove proteins, such as pUL50, as the multi-interacting, major determinants of NEC formation and egress. This review provides closer insight into (i) sequence and structure conservation of herpesviral core NEC proteins, (ii) experimentation on cross-viral core NEC interactions, (iii) the essential functional roles of hook and groove proteins for viral replication, (iv) an establishment of assay systems for NEC-directed antiviral research and (v) the validation of NEC as putative antiviral drug targets. Finally, this article provides new insights into the conservation, function and antiviral targeting of herpesviral core NEC proteins and, into the complex regulatory role of hook and groove proteins during the assembly, egress and maturation of infectious virus.
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Zheng M, Jin G, Zhou Z. Post-Translational Modification of Lamins: Mechanisms and Functions. Front Cell Dev Biol 2022; 10:864191. [PMID: 35656549 PMCID: PMC9152177 DOI: 10.3389/fcell.2022.864191] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/17/2022] [Indexed: 12/22/2022] Open
Abstract
Lamins are the ancient type V intermediate filament proteins contributing to diverse biological functions, such as the maintenance of nuclear morphology, stabilization of chromatin architecture, regulation of cell cycle progression, regulation of spatial-temporal gene expressions, and transduction of mechano-signaling. Deregulation of lamins is associated with abnormal nuclear morphology and chromatin disorganization, leading to a variety of diseases such as laminopathy and premature aging, and might also play a role in cancer. Accumulating evidence indicates that lamins are functionally regulated by post-translational modifications (PTMs) including farnesylation, phosphorylation, acetylation, SUMOylation, methylation, ubiquitination, and O-GlcNAcylation that affect protein stabilization and the association with chromatin or associated proteins. The mechanisms by which these PTMs are modified and the relevant functionality become increasingly appreciated as understanding of these changes provides new insights into the molecular mechanisms underlying the laminopathies concerned and novel strategies for the management. In this review, we discussed a range of lamin PTMs and their roles in both physiological and pathological processes, as well as potential therapeutic strategies by targeting lamin PTMs.
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Affiliation(s)
- Mingyue Zheng
- Medical Research Center, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Guoxiang Jin
- Medical Research Center, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Zhongjun Zhou
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong SAR, China
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The Oligomeric Assemblies of Cytomegalovirus Core Nuclear Egress Proteins Are Associated with Host Kinases and Show Sensitivity to Antiviral Kinase Inhibitors. Viruses 2022; 14:v14051021. [PMID: 35632762 PMCID: PMC9146606 DOI: 10.3390/v14051021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/03/2022] [Accepted: 05/09/2022] [Indexed: 02/04/2023] Open
Abstract
The nucleo-cytoplasmic capsid egress of herpesviruses is a unique regulated process that ensures the efficiency of viral replication and release. For human cytomegalovirus (HCMV), the core of the nuclear egress complex (NEC) consists of the pUL50–pUL53 heterodimer that is able to oligomerize and thus to build hexameric lattices. These structures determine capsid binding and multicomponent protein interaction including NEC-associated host factors. The underlying characteristic of the core NEC formation is based on the N-terminal hook structure of pUL53 that binds into an alpha-helical groove of pUL50, and is thus described as a hook-into-groove interaction. This central regulatory element has recently been validated as a target of antiviral strategies, and first NEC-targeted prototypes of inhibitory small molecules were reported by our previous study. Here, we further analyzed the oligomerization properties of the viral NEC through an approach of chemical protein cross-linking. Findings were as follows: (i) a cross-link approach demonstrated the oligomeric state of the HCMV core NEC using material from HCMV-infected or plasmid-transfected cells, (ii) a Western blot-based identification of NEC-associated kinases using the cross-linked multicomponent NECs was successful, and (iii) we demonstrated the NEC-inhibitory and antiviral activity of specific inhibitors directed to these target kinases. Combined, the results strongly underline the functional importance of the oligomerization of the HCMV-specific NEC that is both phosphorylation-dependent and sensitive to antiviral kinase inhibitors.
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The Conserved Herpesviridae Protein Kinase (CHPK) of Gallid alphaherpesvirus 3 (GaHV3) Is Required for Horizontal Spread and Natural Infection in Chickens. Viruses 2022; 14:v14030586. [PMID: 35336996 PMCID: PMC8955875 DOI: 10.3390/v14030586] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/07/2022] [Accepted: 03/09/2022] [Indexed: 02/04/2023] Open
Abstract
We have formerly identified the conserved herpesvirus protein kinase (CHPK) as essential for horizontal transmission of Marek’s disease virus (MDV). Thus far, it has been confirmed that the mutation of the invariant lysine (K) of CHPKs abrogates kinase activity and that CHPK activity is required for MDV horizontal transmission. Since CHPK is conserved among all members of the Herpesviridae, we hypothesized that CHPK, and specifically its kinase activity, is important for the horizontal transmission of other herpesviruses. To test this hypothesis, we utilized our experimental and natural infection model in chickens with MD vaccine strain 301B/1 of Gallid alphaherpesvirus 3 (GaHV3). First, we mutated the invariant lysine (K) 157 of 301B/1 CHPK to alanine (A) and determined whether it was required for horizontal transmission. To confirm the requirement of 301B/1 CHPK activity for transmission, a rescued virus was generated in which the A157 was changed back to a K (A157K). Despite both the CHPK mutant (K157A) and rescuant (A157K) viruses having replication defects in vivo, only the CHPK mutant (K157A) was unable to spread to contact chickens, while both wild-type and rescuant (A157K) viruses transmitted efficiently, confirming the importance of CHPK activity for horizontal spread. The data confirm that CHPK is required for GaHV3 transmission and suggest that the requirement of avian CHPKs for natural infection is conserved.
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Wild M, Hahn F, Brückner N, Schütz M, Wangen C, Wagner S, Sommerer M, Strobl S, Marschall M. Cyclin-Dependent Kinases (CDKs) and the Human Cytomegalovirus-Encoded CDK Ortholog pUL97 Represent Highly Attractive Targets for Synergistic Drug Combinations. Int J Mol Sci 2022; 23:ijms23052493. [PMID: 35269635 PMCID: PMC8910733 DOI: 10.3390/ijms23052493] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/15/2022] [Accepted: 02/22/2022] [Indexed: 12/13/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a pathogenic human herpesvirus associated with serious, potentially life-threatening symptoms in the immunocompromised or immunonaïve host. The limitations encountered by antiviral therapy options currently available include a narrow panel of accessible targets, the induction of viral drug resistance as well as severe drug dosage-mediated side-effects. Improved drug-targeting strategies to resolve these issues are the focus of our investigations. In particular, pharmaceutical kinase inhibitors (PKIs), either directed to host kinases or directed to the viral protein kinase pUL97, have been considered to overcome these restrictions. Recently, we reported the identification of a synergistic combination of two PKIs directed to host cyclin-dependent kinase 7 (CDK7) and viral CDK ortholog pUL97. Here, we substantiate these findings with the following results: (i) true drug synergy was exhibited by various chemical classes of PKI pairs directed to pUL97 and CDK7; (ii) no putative amplification of cytotoxicity by these drug combinations was observed; (iii) a reduction in drug dosage levels for synergistic combinations was defined on a quantitative basis and compared to monotreatments; (iv) the quantities of target proteins CDK7 and pUL97 expressed in HCMV-infected cells were assessed by confocal imaging, indicating a strong down-modulation of CDK7 levels as a result of synergistic drug treatment; (v) the functional importance of these target kinases, both binding to cyclin H, was illustrated by assessing HCMV replication under the viral genomic deletion of ORF-UL97 or cellular cyclin knock-out; (vi) new combinations of HCMV-specific drug synergy were demonstrated for solely host-directed treatments using PKIs against CDK2, CDK7, CDK8 and/or CDK9 and (vii) a triple PKI combination provided further support for the synergy approach. With these combined findings, this study highlights the potential of therapeutic drug combinations of approved, developmental and preclinical PKIs for expanding future options for anti-HCMV therapy.
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Affiliation(s)
- Markus Wild
- Institute for Clinical and Molecular Virology, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (F.H.); (N.B.); (M.S.); (C.W.); (S.W.); (M.S.)
| | - Friedrich Hahn
- Institute for Clinical and Molecular Virology, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (F.H.); (N.B.); (M.S.); (C.W.); (S.W.); (M.S.)
| | - Nadine Brückner
- Institute for Clinical and Molecular Virology, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (F.H.); (N.B.); (M.S.); (C.W.); (S.W.); (M.S.)
| | - Martin Schütz
- Institute for Clinical and Molecular Virology, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (F.H.); (N.B.); (M.S.); (C.W.); (S.W.); (M.S.)
| | - Christina Wangen
- Institute for Clinical and Molecular Virology, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (F.H.); (N.B.); (M.S.); (C.W.); (S.W.); (M.S.)
| | - Sabrina Wagner
- Institute for Clinical and Molecular Virology, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (F.H.); (N.B.); (M.S.); (C.W.); (S.W.); (M.S.)
| | - Mona Sommerer
- Institute for Clinical and Molecular Virology, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (F.H.); (N.B.); (M.S.); (C.W.); (S.W.); (M.S.)
| | - Stefan Strobl
- 4SC AG/4SC Discovery GmbH, Fraunhoferstraße 22, 82152 Planegg-Martinsried, Germany;
- BioNTech SE, Am Klopferspitz 19a, 82152 Planegg-Martinsried, Germany
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (F.H.); (N.B.); (M.S.); (C.W.); (S.W.); (M.S.)
- Correspondence: ; Tel.: +49-9131-8526089
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Tyl MD, Betsinger CN, Cristea IM. Virus-host protein interactions as footprints of human cytomegalovirus replication. Curr Opin Virol 2022; 52:135-147. [PMID: 34923282 PMCID: PMC8844139 DOI: 10.1016/j.coviro.2021.11.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 11/24/2021] [Indexed: 02/03/2023]
Abstract
Human cytomegalovirus (HCMV) is a pervasive β-herpesvirus that causes lifelong infection. The lytic replication cycle of HCMV is characterized by global organelle remodeling and dynamic virus-host interactions, both of which are necessary for productive HCMV replication. With the advent of new technologies for investigating protein-protein and protein-nucleic acid interactions, numerous critical interfaces between HCMV and host cells have been identified. Here, we review temporal and spatial virus-host interactions that support different stages of the HCMV replication cycle. Understanding how HCMV interacts with host cells during entry, replication, and assembly, as well as how it interfaces with host cell metabolism and immune responses promises to illuminate processes that underlie the biology of infection and the resulting pathologies.
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Affiliation(s)
- Matthew D. Tyl
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA
| | - Cora N. Betsinger
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA
| | - Ileana M. Cristea
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA,Corresponding author and lead contact: Ileana M. Cristea, 210 Lewis Thomas Laboratory, Department of Molecular Biology, Princeton University, Princeton, NJ 08544, Tel: 6092589417, Fax: 6092584575,
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14
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Horníková L, Bruštíková K, Huérfano S, Forstová J. Nuclear Cytoskeleton in Virus Infection. Int J Mol Sci 2022; 23:ijms23010578. [PMID: 35009004 PMCID: PMC8745530 DOI: 10.3390/ijms23010578] [Citation(s) in RCA: 2] [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: 11/18/2021] [Revised: 12/30/2021] [Accepted: 01/03/2022] [Indexed: 02/04/2023] Open
Abstract
The nuclear lamina is the main component of the nuclear cytoskeleton that maintains the integrity of the nucleus. However, it represents a natural barrier for viruses replicating in the cell nucleus. The lamina blocks viruses from being trafficked to the nucleus for replication, but it also impedes the nuclear egress of the progeny of viral particles. Thus, viruses have evolved mechanisms to overcome this obstacle. Large viruses induce the assembly of multiprotein complexes that are anchored to the inner nuclear membrane. Important components of these complexes are the viral and cellular kinases phosphorylating the lamina and promoting its disaggregation, therefore allowing virus egress. Small viruses also use cellular kinases to induce lamina phosphorylation and the subsequent disruption in order to facilitate the import of viral particles during the early stages of infection or during their nuclear egress. Another component of the nuclear cytoskeleton, nuclear actin, is exploited by viruses for the intranuclear movement of their particles from the replication sites to the nuclear periphery. This study focuses on exploitation of the nuclear cytoskeleton by viruses, although this is just the beginning for many viruses, and promises to reveal the mechanisms and dynamic of physiological and pathological processes in the nucleus.
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15
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Sanchez V, Britt W. Human Cytomegalovirus Egress: Overcoming Barriers and Co-Opting Cellular Functions. Viruses 2021; 14:v14010015. [PMID: 35062219 PMCID: PMC8778548 DOI: 10.3390/v14010015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 12/06/2021] [Accepted: 12/16/2021] [Indexed: 12/11/2022] Open
Abstract
The assembly of human cytomegalovirus (HCMV) and other herpesviruses includes both nuclear and cytoplasmic phases. During the prolonged replication cycle of HCMV, the cell undergoes remarkable changes in cellular architecture that include marked increases in nuclear size and structure as well as the reorganization of membranes in cytoplasm. Similarly, significant changes occur in cellular metabolism, protein trafficking, and cellular homeostatic functions. These cellular modifications are considered integral in the efficient assembly of infectious progeny in productively infected cells. Nuclear egress of HCMV nucleocapsids is thought to follow a pathway similar to that proposed for other members of the herpesvirus family. During this process, viral nucleocapsids must overcome structural barriers in the nucleus that limit transit and, ultimately, their delivery to the cytoplasm for final assembly of progeny virions. HCMV, similar to other herpesviruses, encodes viral functions that co-opt cellular functions to overcome these barriers and to bridge the bilaminar nuclear membrane. In this brief review, we will highlight some of the mechanisms that define our current understanding of HCMV egress, relying heavily on the current understanding of egress of the more well-studied α-herpesviruses, HSV-1 and PRV.
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Affiliation(s)
- Veronica Sanchez
- Department of Pediatrics, University of Alabama School of Medicine, Birmingham, AL 35294, USA;
- Correspondence:
| | - William Britt
- Department of Pediatrics, University of Alabama School of Medicine, Birmingham, AL 35294, USA;
- Department of Microbiology, University of Alabama School of Medicine, Birmingham, AL 35294, USA
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16
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Hahn F, Hamilton ST, Wangen C, Wild M, Kicuntod J, Brückner N, Follett JEL, Herrmann L, Kheimar A, Kaufer BB, Rawlinson WD, Tsogoeva SB, Marschall M. Development of a PROTAC-Based Targeting Strategy Provides a Mechanistically Unique Mode of Anti-Cytomegalovirus Activity. Int J Mol Sci 2021; 22:12858. [PMID: 34884662 PMCID: PMC8657773 DOI: 10.3390/ijms222312858] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/24/2021] [Accepted: 11/24/2021] [Indexed: 12/31/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a major pathogenic herpesvirus that is prevalent worldwide and it is associated with a variety of clinical symptoms. Current antiviral therapy options do not fully satisfy the medical needs; thus, improved drug classes and drug-targeting strategies are required. In particular, host-directed antivirals, including pharmaceutical kinase inhibitors, might help improve the drug qualities. Here, we focused on utilizing PROteolysis TArgeting Chimeras (PROTACs), i.e., hetero-bifunctional molecules containing two elements, namely a target-binding molecule and a proteolysis-inducing element. Specifically, a PROTAC that was based on a cyclin-dependent kinase (CDK) inhibitor, i.e., CDK9-directed PROTAC THAL-SNS032, was analyzed and proved to possess strong anti-HCMV AD169-GFP activity, with values of EC50 of 0.030 µM and CC50 of 0.175 µM (SI of 5.8). Comparing the effect of THAL-SNS032 with its non-PROTAC counterpart SNS032, data indicated a 3.7-fold stronger anti-HCMV efficacy. This antiviral activity, as illustrated for further clinically relevant strains of human and murine CMVs, coincided with the mid-nanomolar concentration range necessary for a drug-induced degradation of the primary (CDK9) and secondary targets (CDK1, CDK2, CDK7). In addition, further antiviral activities were demonstrated, such as the inhibition of SARS-CoV-2 replication, whereas other investigated human viruses (i.e., varicella zoster virus, adenovirus type 2, and Zika virus) were found insensitive. Combined, the antiviral quality of this approach is seen in its (i) mechanistic uniqueness; (ii) future options of combinatorial drug treatment; (iii) potential broad-spectrum activity; and (iv) applicability in clinically relevant antiviral models. These novel data are discussed in light of the current achievements of anti-HCMV drug development.
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Affiliation(s)
- Friedrich Hahn
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (C.W.); (M.W.); (J.K.); (N.B.)
| | - Stuart T. Hamilton
- Serology and Virology Division, NSW Health Pathology Microbiology, Prince of Wales Hospital, Schools of Women’s and Children’s Health, Medicine and Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2031, Australia; (S.T.H.); (J.E.L.F.); (W.D.R.)
| | - Christina Wangen
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (C.W.); (M.W.); (J.K.); (N.B.)
| | - Markus Wild
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (C.W.); (M.W.); (J.K.); (N.B.)
| | - Jintawee Kicuntod
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (C.W.); (M.W.); (J.K.); (N.B.)
| | - Nadine Brückner
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (C.W.); (M.W.); (J.K.); (N.B.)
| | - Jasmine E. L. Follett
- Serology and Virology Division, NSW Health Pathology Microbiology, Prince of Wales Hospital, Schools of Women’s and Children’s Health, Medicine and Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2031, Australia; (S.T.H.); (J.E.L.F.); (W.D.R.)
| | - Lars Herrmann
- Institute of Organic Chemistry I, FAU, 91058 Erlangen, Germany; (L.H.); (S.B.T.)
| | - Ahmed Kheimar
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (A.K.); (B.B.K.)
| | - Benedikt B. Kaufer
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (A.K.); (B.B.K.)
| | - William D. Rawlinson
- Serology and Virology Division, NSW Health Pathology Microbiology, Prince of Wales Hospital, Schools of Women’s and Children’s Health, Medicine and Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2031, Australia; (S.T.H.); (J.E.L.F.); (W.D.R.)
| | - Svetlana B. Tsogoeva
- Institute of Organic Chemistry I, FAU, 91058 Erlangen, Germany; (L.H.); (S.B.T.)
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (C.W.); (M.W.); (J.K.); (N.B.)
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Song K, Wu Y, Fu B, Wang L, Hao W, Hua F, Sun Y, Dorf ME, Li S. Leaked Mitochondrial C1QBP Inhibits Activation of the DNA Sensor cGAS. THE JOURNAL OF IMMUNOLOGY 2021; 207:2155-2166. [PMID: 34526378 DOI: 10.4049/jimmunol.2100392] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/16/2021] [Indexed: 01/04/2023]
Abstract
Cytosolic DNA from pathogens activates the DNA sensor cyclic GMP-AMP (cGAMP) synthase (cGAS) that produces the second messenger, cGAMP. cGAMP triggers a signal cascade leading to type I IFN expression. Host DNA is normally restricted in the cellular compartments of the nucleus and mitochondria. Recent studies have shown that DNA virus infection triggers mitochondrial stress, leading to the release of mitochondrial DNA to the cytosol and activation of cGAS; however, the regulatory mechanism of mitochondrial DNA-mediated cGAS activation is not well elucidated. In this study, we analyzed cGAS protein interactome in mouse RAW264.7 macrophages and found that cGAS interacted with C1QBP. C1QBP predominantly localized in the mitochondria and leaked into the cytosol during DNA virus infection. The leaked C1QBP bound the NTase domain of cGAS and inhibited cGAS enzymatic activity in cells and in vitro. Overexpression of the cytosolic form of C1QBP inhibited cytosolic DNA-elicited innate immune responses and promoted HSV-1 infection. By contrast, deficiency of C1QBP led to the elevated innate immune responses and impaired HSV-1 infection. Taken together, our study suggests that C1QBP is a novel cGAS inhibitor hidden in the mitochondria.
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Affiliation(s)
- Kun Song
- Department of Microbiology and Immunology, Tulane University, New Orleans, LA; and
| | - Yakun Wu
- Department of Microbiology and Immunology, Tulane University, New Orleans, LA; and
| | - Bishi Fu
- Department of Immunology, Harvard Medical School, Boston, MA
| | - Lingyan Wang
- Department of Microbiology and Immunology, Tulane University, New Orleans, LA; and
| | - Wenzhuo Hao
- Department of Microbiology and Immunology, Tulane University, New Orleans, LA; and
| | - Fang Hua
- Department of Microbiology and Immunology, Tulane University, New Orleans, LA; and
| | - Yiwen Sun
- Department of Microbiology and Immunology, Tulane University, New Orleans, LA; and
| | - Martin E Dorf
- Department of Immunology, Harvard Medical School, Boston, MA
| | - Shitao Li
- Department of Microbiology and Immunology, Tulane University, New Orleans, LA; and
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18
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Hassan Z, Kumar ND, Reggiori F, Khan G. How Viruses Hijack and Modify the Secretory Transport Pathway. Cells 2021; 10:2535. [PMID: 34685515 PMCID: PMC8534161 DOI: 10.3390/cells10102535] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/28/2021] [Accepted: 09/06/2021] [Indexed: 12/23/2022] Open
Abstract
Eukaryotic cells contain dynamic membrane-bound organelles that are constantly remodeled in response to physiological and environmental cues. Key organelles are the endoplasmic reticulum, the Golgi apparatus and the plasma membrane, which are interconnected by vesicular traffic through the secretory transport route. Numerous viruses, especially enveloped viruses, use and modify compartments of the secretory pathway to promote their replication, assembly and cell egression by hijacking the host cell machinery. In some cases, the subversion mechanism has been uncovered. In this review, we summarize our current understanding of how the secretory pathway is subverted and exploited by viruses belonging to Picornaviridae, Coronaviridae, Flaviviridae,Poxviridae, Parvoviridae and Herpesviridae families.
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Affiliation(s)
- Zubaida Hassan
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates;
- Department of Microbiology, School of Life Sciences, Modibbo Adama University, Yola PMB 2076, Nigeria
| | - Nilima Dinesh Kumar
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands; (N.D.K.); (F.R.)
- Department of Medical Microbiology and Infection Prevention, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands; (N.D.K.); (F.R.)
| | - Gulfaraz Khan
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates;
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Mechanism of Nuclear Lamina Disruption and the Role of pUS3 in HSV-1 Nuclear Egress. J Virol 2021; 95:JVI.02432-20. [PMID: 33658339 PMCID: PMC8139644 DOI: 10.1128/jvi.02432-20] [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] [Indexed: 11/20/2022] Open
Abstract
Herpes simplex virus capsid envelopment at the nuclear membrane is coordinated by nuclear egress complex (NEC) proteins, pUL34 and pUL31, and is accompanied by alteration in the nuclear architecture and local disruption of nuclear lamina. Here, we examined the role of capsid envelopment in the changes of the nuclear architecture by characterizing HSV-1 recombinants that do not form capsids. Typical changes in nuclear architecture and disruption of the lamina were observed in the absence of capsids, suggesting that disruption of the nuclear lamina occurs prior to capsid envelopment. Surprisingly, in the absence of capsid envelopment, lamin A/C becomes concentrated at the nuclear envelope in a pUL34-independent and cell type-specific manner, suggesting that ongoing nuclear egress may be required for the dispersal of lamins observed in wild-type infection. Mutation of virus-encoded protein kinase, pUS3, on a wild-type virus background has been shown to cause accumulation of perinuclear enveloped capsids, formation of NEC aggregates, and exacerbated lamina disruption. We observed that mutation of US3 in the absence of capsids results in identical NEC aggregation and lamina disruption phenotypes, suggesting that they do not result from accumulation of perinuclear virions. TEM analysis revealed that, in the absence of capsids, NEC aggregates correspond to multi-folded nuclear membrane structures, suggesting that pUS3 may control NEC self-association and membrane deformation. To determine the significance of the pUS3 nuclear egress function for virus growth, the replication of single and double UL34 and US3 mutants was measured, showing that the significance of pUS3 nuclear egress function is cell-type specific.ImportanceThe nuclear lamina is an important player in infection by viruses that replicate in the nucleus. Herpesviruses alter the structure of the nuclear lamina to facilitate transport of capsids from the nucleus to the cytoplasm and use both viral and cellular effectors to disrupt the protein-protein interactions that maintain the lamina. Here we explore the role of capsid envelopment and the virus-encoded protein kinase, pUS3, in the disruption of lamina structure. We show that capsid envelopment is not necessary for the lamina disruption, or for US3 mutant phenotypes, including exaggerated lamina disruption, that accompany nuclear egress. These results clarify the mechanisms behind alteration of nuclear lamina structure and support a function for pUS3 in regulating the aggregation state of the nuclear egress machinery.
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20
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Lee CP, Chen MR. Conquering the Nuclear Envelope Barriers by EBV Lytic Replication. Viruses 2021; 13:702. [PMID: 33919628 PMCID: PMC8073350 DOI: 10.3390/v13040702] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/14/2021] [Accepted: 04/14/2021] [Indexed: 12/14/2022] Open
Abstract
The nuclear envelope (NE) of eukaryotic cells has a highly structural architecture, comprising double lipid-bilayer membranes, nuclear pore complexes, and an underlying nuclear lamina network. The NE structure is held in place through the membrane-bound LINC (linker of nucleoskeleton and cytoskeleton) complex, spanning the inner and outer nuclear membranes. The NE functions as a barrier between the nucleus and cytoplasm and as a transverse scaffold for various cellular processes. Epstein-Barr virus (EBV) is a human pathogen that infects most of the world's population and is associated with several well-known malignancies. Within the nucleus, the replicated viral DNA is packaged into capsids, which subsequently egress from the nucleus into the cytoplasm for tegumentation and final envelopment. There is increasing evidence that viral lytic gene expression or replication contributes to the pathogenesis of EBV. Various EBV lytic proteins regulate and modulate the nuclear envelope structure in different ways, especially the viral BGLF4 kinase and the nuclear egress complex BFRF1/BFRF2. From the aspects of nuclear membrane structure, viral components, and fundamental nucleocytoplasmic transport controls, this review summarizes our findings and recently updated information on NE structure modification and NE-related cellular processes mediated by EBV.
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Affiliation(s)
- Chung-Pei Lee
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei 112303, Taiwan;
| | - Mei-Ru Chen
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei 100233, Taiwan
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21
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Häge S, Sonntag E, Svrlanska A, Borst EM, Stilp AC, Horsch D, Müller R, Kropff B, Milbradt J, Stamminger T, Schlötzer-Schrehardt U, Marschall M. Phenotypical Characterization of the Nuclear Egress of Recombinant Cytomegaloviruses Reveals Defective Replication upon ORF-UL50 Deletion but Not pUL50 Phosphosite Mutation. Viruses 2021; 13:v13020165. [PMID: 33499341 PMCID: PMC7911381 DOI: 10.3390/v13020165] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 12/19/2022] Open
Abstract
Nuclear egress is a common herpesviral process regulating nucleocytoplasmic capsid release. For human cytomegalovirus (HCMV), the nuclear egress complex (NEC) is determined by the pUL50-pUL53 core that regulates multicomponent assembly with NEC-associated proteins and capsids. Recently, NEC crystal structures were resolved for α-, β- and γ-herpesviruses, revealing profound structural conservation, which was not mirrored, however, by primary sequence and binding properties. The NEC binding principle is based on hook-into-groove interaction through an N-terminal hook-like pUL53 protrusion that embraces an α-helical pUL50 binding groove. So far, pUL50 has been considered as the major kinase-interacting determinant and massive phosphorylation of pUL50-pUL53 was assigned to NEC formation and functionality. Here, we addressed the question of phenotypical changes of ORF-UL50-mutated HCMVs. Surprisingly, our analyses did not detect a predominant replication defect for most of these viral mutants, concerning parameters of replication kinetics (qPCR), viral protein production (Western blot/CoIP) and capsid egress (confocal imaging/EM). Specifically, only the ORF-UL50 deletion rescue virus showed a block of genome synthesis during late stages of infection, whereas all phosphosite mutants exhibited marginal differences compared to wild-type or revertants. These results (i) emphasize a rate-limiting function of pUL50 for nuclear egress, and (ii) demonstrate that mutations in all mapped pUL50 phosphosites may be largely compensated. A refined mechanistic concept points to a multifaceted nuclear egress regulation, for which the dependence on the expression and phosphorylation of pUL50 is discussed.
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Affiliation(s)
- Sigrun Häge
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Eric Sonntag
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Adriana Svrlanska
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Eva Maria Borst
- Institute of Virology, Hannover Medical School (MHH), 30625 Hannover, Germany;
| | - Anne-Charlotte Stilp
- Institute for Virology, Ulm University Medical Center, 89081 Ulm, Germany; (A.-C.S.); (T.S.)
| | - Deborah Horsch
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Regina Müller
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Barbara Kropff
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Jens Milbradt
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Thomas Stamminger
- Institute for Virology, Ulm University Medical Center, 89081 Ulm, Germany; (A.-C.S.); (T.S.)
| | | | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
- Correspondence: ; Tel.: +49-9131-8526089
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22
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Wild M, Kicuntod J, Seyler L, Wangen C, Bertzbach LD, Conradie AM, Kaufer BB, Wagner S, Michel D, Eickhoff J, Tsogoeva SB, Bäuerle T, Hahn F, Marschall M. Combinatorial Drug Treatments Reveal Promising Anticytomegaloviral Profiles for Clinically Relevant Pharmaceutical Kinase Inhibitors (PKIs). Int J Mol Sci 2021; 22:ijms22020575. [PMID: 33430060 PMCID: PMC7826512 DOI: 10.3390/ijms22020575] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/24/2020] [Accepted: 01/04/2021] [Indexed: 12/11/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a human pathogenic herpesvirus associated with a variety of clinical symptoms. Current antiviral therapy is not always effective, so that improved drug classes and drug-targeting strategies are needed. Particularly host-directed antivirals, including pharmaceutical kinase inhibitors (PKIs), may help to overcome problems of drug resistance. Here, we focused on utilizing a selection of clinically relevant PKIs and determined their anticytomegaloviral efficacies. Particularly, PKIs directed to host or viral cyclin-dependent kinases, i.e., abemaciclib, LDC4297 and maribavir, exerted promising profiles against human and murine cytomegaloviruses. The anti-HCMV in vitro activity of the approved anti-cancer drug abemaciclib was confirmed in vivo using our luciferase-based murine cytomegalovirus (MCMV) animal model in immunocompetent mice. To assess drug combinations, we applied the Bliss independence checkerboard and Loewe additivity fixed-dose assays in parallel. Results revealed that (i) both affirmative approaches provided valuable information on anti-CMV drug efficacies and interactions, (ii) the analyzed combinations comprised additive, synergistic or antagonistic drug interactions consistent with the drugs’ antiviral mode-of-action, (iii) the selected PKIs, especially LDC4297, showed promising inhibitory profiles, not only against HCMV but also other α-, β- and γ-herpesviruses, and specifically, (iv) the combination treatment with LDC4297 and maribavir revealed a strong synergism against HCMV, which might open doors towards novel clinical options in the near future. Taken together, this study highlights the potential of therapeutic drug combinations of current developmental/preclinical PKIs.
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Affiliation(s)
- Markus Wild
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (J.K.); (C.W.); (S.W.); (F.H.)
| | - Jintawee Kicuntod
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (J.K.); (C.W.); (S.W.); (F.H.)
| | - Lisa Seyler
- Institute of Radiology, University Medical Center Erlangen, FAU, Palmsanlage 5, 91054 Erlangen, Germany; (L.S.); (T.B.)
| | - Christina Wangen
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (J.K.); (C.W.); (S.W.); (F.H.)
| | - Luca D. Bertzbach
- Institute of Virology, Freie Universität Berlin, Robert-von-Ostertag-Straße 7-13, 14163 Berlin, Germany; (L.D.B.); (A.M.C.); (B.B.K.)
| | - Andelé M. Conradie
- Institute of Virology, Freie Universität Berlin, Robert-von-Ostertag-Straße 7-13, 14163 Berlin, Germany; (L.D.B.); (A.M.C.); (B.B.K.)
| | - Benedikt B. Kaufer
- Institute of Virology, Freie Universität Berlin, Robert-von-Ostertag-Straße 7-13, 14163 Berlin, Germany; (L.D.B.); (A.M.C.); (B.B.K.)
| | - Sabrina Wagner
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (J.K.); (C.W.); (S.W.); (F.H.)
| | - Detlef Michel
- Institute for Virology, Ulm University Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany;
| | - Jan Eickhoff
- Lead Discovery Center GmbH, Otto-Hahn-Str. 15, 44227 Dortmund, Germany;
| | - Svetlana B. Tsogoeva
- Institute of Organic Chemistry I, FAU, Nikolaus-Fiebiger-Straße 10, 91058 Erlangen, Germany;
| | - Tobias Bäuerle
- Institute of Radiology, University Medical Center Erlangen, FAU, Palmsanlage 5, 91054 Erlangen, Germany; (L.S.); (T.B.)
| | - Friedrich Hahn
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (J.K.); (C.W.); (S.W.); (F.H.)
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054 Erlangen, Germany; (M.W.); (J.K.); (C.W.); (S.W.); (F.H.)
- Correspondence: ; Tel.: +49-9131-8526-089
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23
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Molenberghs F, Bogers JJ, De Vos WH. Confined no more: Viral mechanisms of nuclear entry and egress. Int J Biochem Cell Biol 2020; 129:105875. [PMID: 33157236 DOI: 10.1016/j.biocel.2020.105875] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 12/14/2022]
Abstract
Viruses are obligatory intracellular parasites. For their efficient replication, many require access to the nuclear interior. Yet, only few viral particles are small enough to passively diffuse through the nuclear pore complexes, calling for alternative strategies to bypass the nuclear envelope barrier. Some viruses will await mitotic nuclear envelope breakdown to gain access, whereas others will exploit more active means, for instance by hijacking nuclear pore transport or by directly targeting constituents of the nuclear envelope so as to remodel and temporarily perturb its integrity. After replication, newly produced viral DNA complexes need to cross the same barrier to exit the nucleus and enter the cytoplasm, where the final stages of virion maturation take place. There are also different flavours to the feat of nuclear egress that vary in delicacy and intensity. In this review, we define the major entry and egress strategies that are exploited by different viruses and describe the molecular details thereof. Ultimately, a deeper understanding of these pathways may help identifying molecular targets for blocking viral reproduction or spreading.
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Affiliation(s)
- Freya Molenberghs
- Laboratory of Cell Biology and Histology, Department of Veterinary Sciences/Medicine and Health Sciences, University of Antwerp, Belgium
| | - Johannes J Bogers
- Laboratory of Cell Biology and Histology, Department of Veterinary Sciences/Medicine and Health Sciences, University of Antwerp, Belgium
| | - Winnok H De Vos
- Laboratory of Cell Biology and Histology, Department of Veterinary Sciences/Medicine and Health Sciences, University of Antwerp, Belgium.
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24
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Yang L, Hu X, Cheng A, Wang M, Jia R, Yang Q, Wu Y, Chen S, Liu M, Zhu D, Ou X, Wen X, Mao S, Sun D, Zhang S, Zhao X, Huang J, Gao Q, Liu Y, Yu Y, Zhang L, Tian B, Pan L, Chen X. Two nuclear localization signals regulate intracellular localization of the duck enteritis virus UL13 protein. Poult Sci 2020; 100:26-38. [PMID: 33357689 PMCID: PMC7772677 DOI: 10.1016/j.psj.2020.09.069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 09/12/2020] [Accepted: 09/23/2020] [Indexed: 11/15/2022] Open
Abstract
Duck enteritis virus (DEV) multifunctional tegument protein UL13 is predicted to be a conserved herpesvirus protein kinase; however, little is known about its subcellular localization signal. In this study, through transfection of 2 predicted nuclear signals of DEV UL13 fused to enhanced green fluorescent protein, 2 bipartite nuclear localization signals (NLS) were identified. We found that ivermectin blocked the NLS-mediated nuclear import of DEV UL13, showing that the nuclear localization signal of DEV UL13 is a classical importin α- and β-dependent process. We constructed a DEV UL13 mutant strain in which the NLS of DEV UL13 was deleted to explore whether deletion of the NLS affects viral replication. Amino acids 4 to 7 and 90 to 96 were predicted to be NLSs, further proving that nuclear import occurs via a classical importin α- and β-dependent process. We also found that the NLS of pUL13 had no effect on DEV replication in cell culture. Our study enhances the understanding of DEV pUL13. Taken together, these results provide significant information regarding the biological function of pUL13 during DEV infection.
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Affiliation(s)
- Linjiang Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Xixia Hu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China.
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Renyong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Mafeng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Dekang Zhu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Xumin Ou
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - XingJian Wen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Sai Mao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Di Sun
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Shaqiu Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Xinxin Zhao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Juan Huang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Qun Gao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Yunya Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Yanling Yu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Ling Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Bin Tian
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Leichang Pan
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
| | - Xiaoyue Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China; Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, PR China
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25
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Herpes Simplex Virus Organizes Cytoplasmic Membranes To Form a Viral Assembly Center in Neuronal Cells. J Virol 2020; 94:JVI.00900-20. [PMID: 32699089 DOI: 10.1128/jvi.00900-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/15/2020] [Indexed: 11/20/2022] Open
Abstract
Herpes simplex virus (HSV) is a neuroinvasive virus that has been used as a model organism for studying common properties of all herpesviruses. HSV induces host organelle rearrangement and forms multiple, dispersed assembly compartments in epithelial cells, which complicates the study of HSV assembly. In this study, we show that HSV forms a visually distinct unitary cytoplasmic viral assembly center (cVAC) in both cancerous and primary neuronal cells that concentrates viral structural proteins and is a major site of capsid envelopment. The HSV cVAC also concentrates host membranes that are important for viral assembly, such as Golgi- and recycling endosome-derived membranes. Finally, we show that HSV cVAC formation and/or maintenance depends on an intact microtubule network and a viral tegument protein, pUL51. Our observations suggest that the neuronal cVAC is a uniquely useful model to study common herpesvirus assembly pathways and cell-specific pathways for membrane reorganization.IMPORTANCE Herpesvirus particles are complex and contain many different proteins that must come together in an organized and coordinated fashion. Many viruses solve this coordination problem by creating a specialized assembly factory in the host cell, and the formation of such factories provides a promising target for interfering with virus production. Herpes simplex virus 1 (HSV-1) infects several types of cells, including neurons, but has not previously been shown to form such an organized factory in the nonneuronal cells in which its assembly has been best studied. Here, we show that HSV-1 forms an organized assembly factory in neuronal cells, and we identify some of the viral and host cell factors that are important for its formation.
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26
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Abstract
During viral replication, herpesviruses utilize a unique strategy, termed nuclear egress, to translocate capsids from the nucleus into the cytoplasm. This initial budding step transfers a newly formed capsid from within the nucleus, too large to fit through nuclear pores, through the inner nuclear membrane to the perinuclear space. The perinuclear enveloped virion must then fuse with the outer nuclear membrane to be released into the cytoplasm for further maturation, undergoing budding once again at the trans-Golgi network or early endosomes, and ultimately exit the cell non-lytically to spread infection. This first budding process is mediated by two conserved viral proteins, UL31 and UL34, that form a heterodimer called the nuclear egress complex (NEC). This review focuses on what we know about how the NEC mediates capsid transport to the perinuclear space, including steps prior to and after this budding event. Additionally, we discuss the involvement of other viral proteins in this process and how NEC-mediated budding may be regulated during infection.
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Affiliation(s)
- Elizabeth B Draganova
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - Michael K Thorsen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - Ekaterina E Heldwein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
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27
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Marschall M, Häge S, Conrad M, Alkhashrom S, Kicuntod J, Schweininger J, Kriegel M, Lösing J, Tillmanns J, Neipel F, Eichler J, Muller YA, Sticht H. Nuclear Egress Complexes of HCMV and Other Herpesviruses: Solving the Puzzle of Sequence Coevolution, Conserved Structures and Subfamily-Spanning Binding Properties. Viruses 2020; 12:v12060683. [PMID: 32599939 PMCID: PMC7354485 DOI: 10.3390/v12060683] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/19/2020] [Accepted: 06/23/2020] [Indexed: 12/11/2022] Open
Abstract
Herpesviruses uniquely express two essential nuclear egress-regulating proteins forming a heterodimeric nuclear egress complex (core NEC). These core NECs serve as hexameric lattice-structured platforms for capsid docking and recruit viral and cellular NEC-associated factors that jointly exert nuclear lamina as well as membrane-rearranging functions (multicomponent NEC). The regulation of nuclear egress has been profoundly analyzed for murine and human cytomegaloviruses (CMVs) on a mechanistic basis, followed by the description of core NEC crystal structures, first for HCMV, then HSV-1, PRV and EBV. Interestingly, the highly conserved structural domains of these proteins stand in contrast to a very limited sequence conservation of the key amino acids within core NEC-binding interfaces. Even more surprising, although a high functional consistency was found when regarding the basic role of NECs in nuclear egress, a clear specification was identified regarding the limited, subfamily-spanning binding properties of core NEC pairs and NEC multicomponent proteins. This review summarizes the evolving picture of the relationship between sequence coevolution, structural conservation and properties of NEC interaction, comparing HCMV to α-, β- and γ-herpesviruses. Since NECs represent substantially important elements of herpesviral replication that are considered as drug-accessible targets, their putative translational use for antiviral strategies is discussed.
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Affiliation(s)
- Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Medical Center, 91054 Erlangen, Germany; (S.H.); (J.K.); (J.L.); (J.T.); (F.N.)
- Correspondence: ; Tel.: +49-9131-85-26089
| | - Sigrun Häge
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Medical Center, 91054 Erlangen, Germany; (S.H.); (J.K.); (J.L.); (J.T.); (F.N.)
| | - Marcus Conrad
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander University of Erlangen-Nürnberg, 91054 Erlangen, Germany; (M.C.); (H.S.)
| | - Sewar Alkhashrom
- Division of Medicinal Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University of Erlangen-Nürnberg, 91058 Erlangen, Germany; (S.A.); (J.E.)
| | - Jintawee Kicuntod
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Medical Center, 91054 Erlangen, Germany; (S.H.); (J.K.); (J.L.); (J.T.); (F.N.)
| | - Johannes Schweininger
- Division of Biotechnology, Department of Biology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91052 Erlangen, Germany; (J.S.); (M.K.); (Y.A.M.)
| | - Mark Kriegel
- Division of Biotechnology, Department of Biology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91052 Erlangen, Germany; (J.S.); (M.K.); (Y.A.M.)
| | - Josephine Lösing
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Medical Center, 91054 Erlangen, Germany; (S.H.); (J.K.); (J.L.); (J.T.); (F.N.)
| | - Julia Tillmanns
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Medical Center, 91054 Erlangen, Germany; (S.H.); (J.K.); (J.L.); (J.T.); (F.N.)
| | - Frank Neipel
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Medical Center, 91054 Erlangen, Germany; (S.H.); (J.K.); (J.L.); (J.T.); (F.N.)
| | - Jutta Eichler
- Division of Medicinal Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University of Erlangen-Nürnberg, 91058 Erlangen, Germany; (S.A.); (J.E.)
| | - Yves A. Muller
- Division of Biotechnology, Department of Biology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91052 Erlangen, Germany; (J.S.); (M.K.); (Y.A.M.)
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander University of Erlangen-Nürnberg, 91054 Erlangen, Germany; (M.C.); (H.S.)
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A quantitative nuclear egress assay to investigate the nucleocytoplasmic capsid release of human cytomegalovirus. J Virol Methods 2020; 283:113909. [PMID: 32544419 DOI: 10.1016/j.jviromet.2020.113909] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 06/05/2020] [Accepted: 06/07/2020] [Indexed: 11/21/2022]
Abstract
Nuclear egress is a rate-limiting step of herpesviral replication, restricting the nucleocytoplasmic transport of viral capsids. The process is regulated by two viral nuclear egress proteins (core NEC pUL50-pUL53), which recruit additional cellular and viral proteins. The multicomponent NEC mediates disassembly of the nuclear lamina barrier and the docking of nuclear capsids. The quantitation of nuclear egress has been accomplished by electron microscopic analysis, but is generally hampered by the low number of detectable cytoplasmic capsids. A newly established method for the quantitation of viral nuclear egress improves the characterization of viral mutants, host cell permissiveness and antiviral drug efficacy. In this study, various strains of human cytomegalovirus (HCMV) were used to measure the replication efficiencies in primary human fibroblasts, applying methods of cell fractionation, DNase digestion, sucrose cushions and quantitative PCR. Several stages of optimization led to a reliable quantitative assay that allowed the characterization of viral nuclear egress efficacy. Using this assay, recovery of the nuclear egress of a NEC-defective HCMV mutant was quantitatively assessed by applying an inducible NEC-expressing fibroblast culture for trans-complementation. This novel assay system can be further used to accurately quantitate and characterize the functionality of nuclear egress of HCMV or other herpesviruses.
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Couté Y, Kraut A, Zimmermann C, Büscher N, Hesse AM, Bruley C, De Andrea M, Wangen C, Hahn F, Marschall M, Plachter B. Mass Spectrometry-Based Characterization of the Virion Proteome, Phosphoproteome, and Associated Kinase Activity of Human Cytomegalovirus. Microorganisms 2020; 8:microorganisms8060820. [PMID: 32486127 PMCID: PMC7357008 DOI: 10.3390/microorganisms8060820] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 05/28/2020] [Accepted: 05/28/2020] [Indexed: 12/17/2022] Open
Abstract
The assembly of human cytomegalovirus (HCMV) virions is an orchestrated process that requires, as an essential prerequisite, the complex crosstalk between viral structural proteins. Currently, however, the mechanisms governing the successive steps in the constitution of virion protein complexes remain elusive. Protein phosphorylation is a key regulator determining the sequential changes in the conformation, binding, dynamics, and stability of proteins in the course of multiprotein assembly. In this review, we present a comprehensive map of the HCMV virion proteome, including a refined view on the virion phosphoproteome, based on previous publications supplemented by new results. Thus, a novel dataset of viral and cellular proteins contained in HCMV virions is generated, providing a basis for future analyses of individual phosphorylation steps and sites involved in the orchestrated assembly of HCMV virion-specific multiprotein complexes. Finally, we present the current knowledge on the activity of pUL97, the HCMV-encoded and virion-associated kinase, in phosphorylating viral and host proteins.
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Affiliation(s)
- Yohann Couté
- University Grenoble Alpes, CEA, Inserm, BIG-BGE, 38000 Grenoble, France; (A.K.); (A.-M.H.); (C.B.)
- Correspondence: (Y.C.); (B.P.); Tel.: +33-4-38789461 (Y.C.); +49-6131-179232 (B.P.)
| | - Alexandra Kraut
- University Grenoble Alpes, CEA, Inserm, BIG-BGE, 38000 Grenoble, France; (A.K.); (A.-M.H.); (C.B.)
| | - Christine Zimmermann
- Institute for Virology and Forschungszentrum für Immuntherapie, University Medical Center of the Johannes Gutenberg-University Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany; (C.Z.); (N.B.)
| | - Nicole Büscher
- Institute for Virology and Forschungszentrum für Immuntherapie, University Medical Center of the Johannes Gutenberg-University Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany; (C.Z.); (N.B.)
| | - Anne-Marie Hesse
- University Grenoble Alpes, CEA, Inserm, BIG-BGE, 38000 Grenoble, France; (A.K.); (A.-M.H.); (C.B.)
| | - Christophe Bruley
- University Grenoble Alpes, CEA, Inserm, BIG-BGE, 38000 Grenoble, France; (A.K.); (A.-M.H.); (C.B.)
| | - Marco De Andrea
- Department of Public Health and Pediatric Sciences, Turin Medical School, University of Turin, 10126 Turin, and CAAD – Center for Translational Research on Autoimmune and Allergic Disease, Novara Medical School, 28100 Novara, Italy;
| | - Christina Wangen
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (C.W.); (F.H.); (M.M.)
| | - Friedrich Hahn
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (C.W.); (F.H.); (M.M.)
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (C.W.); (F.H.); (M.M.)
| | - Bodo Plachter
- Institute for Virology and Forschungszentrum für Immuntherapie, University Medical Center of the Johannes Gutenberg-University Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany; (C.Z.); (N.B.)
- Correspondence: (Y.C.); (B.P.); Tel.: +33-4-38789461 (Y.C.); +49-6131-179232 (B.P.)
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30
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The Cytomegalovirus Protein Kinase pUL97:Host Interactions, Regulatory Mechanisms and Antiviral Drug Targeting. Microorganisms 2020; 8:microorganisms8040515. [PMID: 32260430 PMCID: PMC7232230 DOI: 10.3390/microorganisms8040515] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/02/2020] [Accepted: 04/02/2020] [Indexed: 12/25/2022] Open
Abstract
Human cytomegalovirus (HCMV) expresses a variety of viral regulatory proteins that undergo close interaction with host factors including viral-cellular multiprotein complexes. The HCMV protein kinase pUL97 represents a viral cyclin-dependent kinase ortholog (vCDK) that determines the efficiency of HCMV replication via phosphorylation of viral and cellular substrates. A hierarchy of functional importance of individual pUL97-mediated phosphorylation events has been discussed; however, the most pronounced pUL97-dependent phenotype could be assigned to viral nuclear egress, as illustrated by deletion of the UL97 gene or pharmacological pUL97 inhibition. Despite earlier data pointing to a cyclin-independent functionality, experimental evidence increasingly emphasized the role of pUL97-cyclin complexes. Consequently, the knowledge about pUL97 involvement in host interaction, viral nuclear egress and additional replicative steps led to the postulation of pUL97 as an antiviral target. Indeed, validation experiments in vitro and in vivo confirmed the sustainability of this approach. Consequently, current investigations of pUL97 in antiviral treatment go beyond the known pUL97-mediated ganciclovir prodrug activation and henceforward include pUL97-specific kinase inhibitors. Among a number of interesting small molecules analyzed in experimental and preclinical stages, maribavir is presently investigated in clinical studies and, in the near future, might represent a first kinase inhibitor applied in the field of antiviral therapy.
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Patterns of Autologous and Nonautologous Interactions Between Core Nuclear Egress Complex (NEC) Proteins of α-, β- and γ-Herpesviruses. Viruses 2020; 12:v12030303. [PMID: 32168891 PMCID: PMC7150769 DOI: 10.3390/v12030303] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 03/06/2020] [Indexed: 12/12/2022] Open
Abstract
Nuclear egress is a regulated process shared by α-, β- and γ-herpesviruses. The core nuclear egress complex (NEC) is composed of the membrane-anchored protein homologs of human cytomegalovirus (HCMV) pUL50, murine cytomegalovirus (MCMV) pM50, Epstein-Barr virus (EBV) BFRF1 or varicella zoster virus (VZV) Orf24, which interact with the autologous NEC partners pUL53, pM53, BFLF2 or Orf27, respectively. Their recruitment of additional proteins leads to the assembly of a multicomponent NEC, coordinately regulating viral nucleocytoplasmic capsid egress. Here, the functionality of VZV, HCMV, MCMV and EBV core NECs was investigated by coimmunoprecipitation and confocal imaging analyses. Furthermore, a recombinant MCMV, harboring a replacement of ORF M50 by UL50, was analyzed both in vitro and in vivo. In essence, core NEC interactions were strictly limited to autologous NEC pairs and only included one measurable nonautologous interaction between the homologs of HCMV and MCMV. A comparative analysis of MCMV-WT versus MCMV-UL50-infected murine fibroblasts revealed almost identical phenotypes on the levels of protein and genomic replication kinetics. In infected BALB/c mice, virus spread to lung and other organs was found comparable between these viruses, thus stating functional complementarity. In conclusion, our study underlines that herpesviral core NEC proteins are functionally conserved regarding complementarity of core NEC interactions, which were found either virus-specific or restricted within subfamilies.
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Expression of the Conserved Herpesvirus Protein Kinase (CHPK) of Marek's Disease Alphaherpesvirus in the Skin Reveals a Mechanistic Importance for CHPK during Interindividual Spread in Chickens. J Virol 2020; 94:JVI.01522-19. [PMID: 31801854 DOI: 10.1128/jvi.01522-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 11/26/2019] [Indexed: 01/01/2023] Open
Abstract
The Herpesviridae encode many conserved genes, including the conserved herpesvirus protein kinase (CHPK) that has multifunctional properties. In most cases, herpesviruses lacking CHPK can propagate in cell culture to various degrees, depending on the virus and cell culture system. However, in the natural animal model system of Marek's disease alphaherpesvirus (MDV) in chickens, CHPK is absolutely required for interindividual spread from chicken to chicken. The lack of biological reagents for chicken and MDV has limited our understanding of this important gene during interindividual spread. Here, we engineered epitope-tagged proteins in the context of virus infection in order to detect CHPK in the host. Using immunofluorescence assays and Western blotting during infection in cell culture and in chickens, we determined that the invariant lysine 170 (K170) of MDV CHPK is required for interindividual spread and autophosphorylation of CHPK and that mutation to methionine (M170) results in instability of the CHPK protein. Using these newly generated viruses allowed us to examine the expression of CHPK in infected chickens, and these results showed that mutant CHPK localization and late viral protein expression were severely affected in feather follicles wherein MDV is shed, providing important information on the requirement of CHPK for interindividual spread.IMPORTANCE Marek's disease in chickens is caused by Gallid alphaherpesvirus 2, better known as Marek's disease alphaherpesvirus (MDV). Current vaccines only reduce tumor formation but do not block interindividual spread from chicken to chicken. Understanding MDV interindividual spread provides important information for the development of potential therapies to protect against Marek's disease while also providing a reliable natural host in order to study herpesvirus replication and pathogenesis in animals. Here, we studied the conserved Herpesviridae protein kinase (CHPK) in cell culture and during infection in chickens. We determined that MDV CHPK is not required for cell-to-cell spread, for disease induction, and for oncogenicity. However, it is required for interindividual spread, and mutation of the invariant lysine (K170) results in stability issues and aberrant expression in chickens. This study is important because it addresses the critical role CHPK orthologs play in the natural host.
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Wang T, Du Q, Niu Y, Zhang X, Wang Z, Wu X, Yang X, Zhao X, Liu SL, Tong D, Huang Y. Cellular p32 Is a Critical Regulator of Porcine Circovirus Type 2 Nuclear Egress. J Virol 2019; 93:e00979-19. [PMID: 31511386 PMCID: PMC6854514 DOI: 10.1128/jvi.00979-19] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/03/2019] [Indexed: 12/25/2022] Open
Abstract
Circoviruses are the smallest DNA viruses known to infect mammalian and avian species. Although circoviruses are known to be associated with a range of clinical diseases, the details of circovirus DNA release still remain unknown. Here, we identified p32 as a key regulator for porcine circoviral nuclear egress. Upon porcine circovirus type 2 (PCV2) infection, p32 was recruited into the nucleus by the viral capsid (Cap) protein; simultaneously, protein kinase C isoform δ (PKC-δ) was phosphorylated at threonine 505 by phospholipase C (PLC)-mediated signaling at the early stage of infection, which was further amplified by Jun N-terminal protein kinase (JNK) and extracellular signal-regulated kinase (ERK) signaling at the late infection phase. p32 functioned as an adaptor to recruit phosphorylated PKC-δ and Cap to the nuclear membrane to phosphorylate lamin A/C, resulting in a rearrangement of nuclear lamina and thus facilitating viral nuclear egress. Consistent with these findings, knockout (KO) of p32 in PCV2-infected cells markedly reduced the phosphorylation of PKC-δ and impeded the recruitment of p-PKC-δ and Cap to the nuclear membrane, hence abolishing the phosphorylation of lamin A/C and the rearrangement of nuclear lamina. As a result, p32 depletion profoundly impaired the production of cell-free viruses during PCV2 infection. We further identified the N-terminal 24RRR26 of Cap to be crucial for binding to p32, and mutation of these three arginine residues significantly weakened the replication and pathogenesis of PCV2 in vivo In summary, our findings highlight a critical role of p32 in the activation and recruitment of PKC-δ to phosphorylate lamin A/C and facilitate porcine circoviral nuclear egress, and they certainly help understanding of the mechanism of PCV2 replication.IMPORTANCE Circovirus infections are highly prevalent in mammalian and avian species. Circoviral capsid protein is the only structural protein of the virion that plays an essential role in viral assembly. However, the machinery of circovirus nuclear egress is currently unknown. In this work, we identified p32 as a key regulator of porcine circovirus type 2 (PCV2) nuclear egress that forms a complex with the viral capsid (Cap) protein to enhance protein kinase C isoform δ (PKC-δ) activity; this resulted in a recruitment of phosphorylated PKC-δ to the nuclear membrane, which further phosphorylates lamin A/C to promote the rearrangement of nuclear lamina and facilitate viral nuclear egress. Notably, we found that the N-terminal 24RRR26 of Cap, a highly conserved motif among circovirus species, was required for interacting with p32, and that mutation of this motif markedly impeded PCV2 nuclear egress. These data indicate that p32 is a critical regulator of PCV2 nuclear egress and reveal the importance of this finding in circovirus replication.
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Affiliation(s)
- Tongtong Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- College of Agronomy, Liaocheng University, Liaocheng, China
| | - Qian Du
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yingying Niu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Xiaohua Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Zhenyu Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Xingchen Wu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - XueFeng Yang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Xiaomin Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Shan-Lu Liu
- Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
- Viruses and Emerging Pathogens Program, Infectious Diseases Institute, The Ohio State University, Columbus, Ohio, USA
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA
| | - Dewen Tong
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yong Huang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
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Human cytomegalovirus overcomes SAMHD1 restriction in macrophages via pUL97. Nat Microbiol 2019; 4:2260-2272. [PMID: 31548682 DOI: 10.1038/s41564-019-0557-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 08/09/2019] [Indexed: 12/30/2022]
Abstract
The host restriction factor sterile alpha motif and histidine-aspartate domain-containing protein 1 (SAMHD1) is an important component of the innate immune system. By regulating the intracellular nucleotide pool, SAMHD1 influences cell division and restricts the replication of viruses that depend on high nucleotide concentrations. Human cytomegalovirus (HCMV) is a pathogenic virus with a tropism for non-dividing myeloid cells, in which SAMHD1 is catalytically active. Here we investigate how HCMV achieves efficient propagation in these cells despite the SAMHD1-mediated dNTP depletion. Our analysis reveals that SAMHD1 has the capability to suppress HCMV replication. However, HCMV has evolved potent countermeasures to circumvent this block. HCMV interferes with SAMHD1 steady-state expression and actively induces SAMHD1 phosphorylation using the viral kinase pUL97 and by hijacking cellular kinases. These actions convert SAMHD1 to its inactive phosphorylated form. This mechanism of SAMHD1 inactivation by phosphorylation might also be used by other viruses to overcome intrinsic immunity.
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35
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Cazorla-Vázquez S, Steingruber M, Marschall M, Engel FB. Human cytomegaloviral multifunctional protein kinase pUL97 impairs zebrafish embryonic development and increases mortality. Sci Rep 2019; 9:7219. [PMID: 31076608 PMCID: PMC6510723 DOI: 10.1038/s41598-019-43649-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 04/26/2019] [Indexed: 12/27/2022] Open
Abstract
Cytomegalovirus is a worldwide-distributed human pathogen, which is the leading cause of congenital virus infection, affecting 0.5 to 2% of live births. To date, it is largely unclear which molecular mechanisms underlie the symptomatic outcomes. This is mainly due to species specificity and limited homology among cytomegalovirus genomes. As it is not possible to infect model organisms with human cytomegalovirus, the aim of this study was to develop a heterologous system allowing in the future the elucidation of the pathological role of individual viral proteins. As a model organism the zebrafish has been chosen due to its ease of manipulation and characterization as well as its large offspring. As cytomegalovirus model protein, pUL97 was characterized because it is multiply involved in virus-host interaction. Here, we show in zebrafish embryos, that (i) pUL97 can be expressed in zebrafish, (ii) increasing pUL97 expression levels quantitatively correlate with both minor and major pathological defects, (iii) pUL97 expression impairs cell cycle progression and induces cell death, (iv) active pUL97, but not an inactive mutant, induces excess mortality, and (v) co-administration of a pUL97 inhibitor reduces embryonic pathology. Collectively, these data indicate the suitability of zebrafish to elucidate the pathological role of human cytomegaloviral proteins.
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Affiliation(s)
- Salvador Cazorla-Vázquez
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 12, 91052, Erlangen, Germany
| | - Mirjam Steingruber
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054, Erlangen, Germany
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, 91054, Erlangen, Germany
| | - Felix B Engel
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 12, 91052, Erlangen, Germany.
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Steingruber M, Keller L, Socher E, Ferre S, Hesse AM, Couté Y, Hahn F, Büscher N, Plachter B, Sticht H, Marschall M. Cyclins B1, T1, and H differ in their molecular mode of interaction with cytomegalovirus protein kinase pUL97. J Biol Chem 2019; 294:6188-6203. [PMID: 30782840 DOI: 10.1074/jbc.ra118.007049] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 02/08/2019] [Indexed: 12/19/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a common β-herpesvirus causing life-long latent infections. HCMV replication interferes with cell cycle regulation in host cells because the HCMV-encoded cyclin-dependent kinase (CDK) ortholog pUL97 extensively phosphorylates the checkpoint regulator retinoblastoma protein. pUL97 also interacts with cyclins B1, T1, and H, and recent findings have strongly suggested that these interactions influence pUL97 substrate recognition. Interestingly, here we detected profound mechanistic differences among these pUL97-cyclin interactions. Our study revealed the following. (i) pUL97 interacts with cyclins B1 and H in a manner dependent on pUL97 activity and HCMV-specific cyclin modulation, respectively. (ii) The phosphorylated state of both proteins is an important determinant of the pUL97-cyclin B1 interaction. (iii) Activated phospho-Thr-315 cyclin H is up-regulated during HCMV replication. (iv) Thr-315 phosphorylation is independent of intracellular pUL97 or CDK7 activity. (v) pUL97-mediated in vitro phosphorylation is detectable for cyclin B1 but not H. (vi) Mutual transphosphorylation between pUL97 and CDK7 is not detectable, and an MS-based phosphosite analysis indicated that pUL97 might unexpectedly not be phosphorylated in its T-loop. (vii) The binary complexes pUL97-cyclin H and CDK7-cyclin H as well as the ternary complex pUL97-cyclin-H-CDK7 are detectable in an assembly-based CoIP approach. (viii) pUL97 self-interaction can be bridged by the transcriptional cyclins T1 or H but not by the classical cell cycle-regulating B1 cyclin. Combined, our findings unravel a number of cyclin type-specific differences in pUL97 interactions and suggest a multifaceted regulatory impact of cyclins on HCMV replication.
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Affiliation(s)
- Mirjam Steingruber
- From the Institute for Clinical and Molecular Virology, 91054 Erlangen, Germany.
| | - Lena Keller
- From the Institute for Clinical and Molecular Virology, 91054 Erlangen, Germany
| | - Eileen Socher
- Division of Bioinformatics, Institute of Biochemistry Friedrich-Alexander University of Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Sabrina Ferre
- the Université Grenoble Alpes, CEA, Inserm, BIG-BGE, 38000 Grenoble, France
| | - Anne-Marie Hesse
- the Université Grenoble Alpes, CEA, Inserm, BIG-BGE, 38000 Grenoble, France
| | - Yohann Couté
- the Université Grenoble Alpes, CEA, Inserm, BIG-BGE, 38000 Grenoble, France
| | - Friedrich Hahn
- From the Institute for Clinical and Molecular Virology, 91054 Erlangen, Germany
| | - Nicole Büscher
- the Institute for Virology, University Medical Center of the Johannes Gutenberg-University Mainz, 55131 Mainz, Germany
| | - Bodo Plachter
- the Institute for Virology, University Medical Center of the Johannes Gutenberg-University Mainz, 55131 Mainz, Germany
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry Friedrich-Alexander University of Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | - Manfred Marschall
- From the Institute for Clinical and Molecular Virology, 91054 Erlangen, Germany.
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37
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Turan A, Grosche L, Krawczyk A, Mühl-Zürbes P, Drassner C, Düthorn A, Kummer M, Hasenberg M, Voortmann S, Jastrow H, Dörrie J, Schaft N, Kraner M, Döhner K, Sodeik B, Steinkasserer A, Heilingloh CS. Autophagic degradation of lamins facilitates the nuclear egress of herpes simplex virus type 1. J Cell Biol 2018; 218:508-523. [PMID: 30587512 PMCID: PMC6363456 DOI: 10.1083/jcb.201801151] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 10/02/2018] [Accepted: 11/08/2018] [Indexed: 01/11/2023] Open
Abstract
Turan and Grosche et al. show that herpes simplex virus type 1 (HSV-1) infection leads to autophagic degradation of nuclear lamins in immature dendritic cells, facilitating HSV-1 nuclear egress and the formation of infectious progeny virus. In mature dendritic cells, autophagy is inhibited due to elevated KIF1B and KIF2A protein levels. Dendritic cells (DCs) are crucial for the induction of potent antiviral immune responses. In contrast to immature DCs (iDCs), mature DCs (mDCs) are not permissive for infection with herpes simplex virus type 1 (HSV-1). Here, we demonstrate that HSV-1 infection of iDCs and mDCs induces autophagy, which promotes the degradation of lamin A/C, B1, and B2 in iDCs only. This in turn facilitates the nuclear egress of progeny viral capsids and thus the formation of new infectious particles. In contrast, lamin protein levels remain stable in HSV-1–infected mDCs due to an inefficient autophagic flux. Elevated protein levels of KIF1B and KIF2A in mDCs inhibited lamin degradation, likely by hampering autophagosome–lysosome fusion. Therefore, in mDCs, fewer progeny capsids were released from the nuclei into the cytosol, and fewer infectious virions were assembled. We hypothesize that inhibition of autophagic lamin degradation in mDCs represents a very powerful cellular counterstrike to inhibit the production of progeny virus and thus viral spread.
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Affiliation(s)
- Aykut Turan
- Department of Immune Modulation, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Linda Grosche
- Department of Immune Modulation, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Adalbert Krawczyk
- Institute for Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Petra Mühl-Zürbes
- Department of Immune Modulation, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Christina Drassner
- Department of Immune Modulation, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Alexandra Düthorn
- Department of Immune Modulation, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Mirko Kummer
- Department of Immune Modulation, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Mike Hasenberg
- Imaging Center Essen, Electron Microscopy Unit, University Hospital of Essen, Essen, Germany
| | - Sylvia Voortmann
- Imaging Center Essen, Electron Microscopy Unit, University Hospital of Essen, Essen, Germany
| | - Holger Jastrow
- Imaging Center Essen, Electron Microscopy Unit, University Hospital of Essen, Essen, Germany.,Institute of Anatomy, University of Duisburg-Essen, Essen, Germany
| | - Jan Dörrie
- Department of Dermatology, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Niels Schaft
- Department of Dermatology, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Max Kraner
- Division of Biochemistry, Department of Biology, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Katinka Döhner
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Beate Sodeik
- Institute of Virology, Hannover Medical School, Hannover, Germany
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38
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Lv Y, Zhou S, Gao S, Deng H. Remodeling of host membranes during herpesvirus assembly and egress. Protein Cell 2018; 10:315-326. [PMID: 30242641 PMCID: PMC6468031 DOI: 10.1007/s13238-018-0577-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 08/21/2018] [Indexed: 02/04/2023] Open
Abstract
Many viruses, enveloped or non-enveloped, remodel host membrane structures for their replication, assembly and escape from host cells. Herpesviruses are important human pathogens and cause many diseases. As large enveloped DNA viruses, herpesviruses undergo several complex steps to complete their life cycles and produce infectious progenies. Firstly, herpesvirus assembly initiates in the nucleus, producing nucleocapsids that are too large to cross through the nuclear pores. Nascent nucleocapsids instead bud at the inner nuclear membrane to form primary enveloped virions in the perinuclear space followed by fusion of the primary envelopes with the outer nuclear membrane, to translocate the nucleocapsids into the cytoplasm. Secondly, nucleocapsids obtain a series of tegument proteins in the cytoplasm and bud into vesicles derived from host organelles to acquire viral envelopes. The vesicles are then transported to and fuse with the plasma membrane to release the mature virions to the extracellular space. Therefore, at least two budding and fusion events take place at cellular membrane structures during herpesviruses assembly and egress, which induce membrane deformations. In this review, we describe and discuss how herpesviruses exploit and remodel host membrane structures to assemble and escape from the host cell.
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Affiliation(s)
- Ying Lv
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Sheng Zhou
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shengyan Gao
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Hongyu Deng
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China. .,CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
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Britt WJ, Prichard MN. New therapies for human cytomegalovirus infections. Antiviral Res 2018; 159:153-174. [PMID: 30227153 DOI: 10.1016/j.antiviral.2018.09.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/28/2018] [Accepted: 09/07/2018] [Indexed: 02/07/2023]
Abstract
The recent approval of letermovir marks a new era of therapy for human cytomegalovirus (HCMV) infections, particularly for the prevention of HCMV disease in hematopoietic stem cell transplant recipients. For almost 30 years ganciclovir has been the therapy of choice for these infections and by today's standards this drug exhibits only modest antiviral activity that is often insufficient to completely suppress viral replication, and drives the selection of drug-resistant variants that continue to replicate and contribute to disease. While ganciclovir remains the therapy of choice, additional drugs that inhibit novel molecular targets, such as letermovir, will be required as highly effective combination therapies are developed not only for the treatment of immunocompromised hosts, but also for congenitally infected infants. Sustained efforts, largely in the biotech industry and academia, have identified additional highly active lead compounds that have progressed into clinical studies with varying levels of success and at least two have the potential to be approved in the near future. Some of the new drugs in the pipeline inhibit new molecular targets, remain effective against isolates that have developed resistance to existing therapies, and promise to augment existing therapeutic regimens. Here, we will describe some of the unique features of HCMV biology and discuss their effect on therapeutic needs. Existing drugs will also be discussed and some of the more promising candidates will be reviewed with an emphasis on those progressing through clinical studies. The in vitro and in vivo antiviral activity, spectrum of antiviral activity, and mechanism of action of new compounds will be reviewed to provide an update on potential new therapies for HCMV infections that have progressed significantly in recent years.
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Affiliation(s)
- William J Britt
- Department of Pediatrics, University of Alabama School of Medicine, Birmingham AL 35233-1711, USA
| | - Mark N Prichard
- Department of Pediatrics, University of Alabama School of Medicine, Birmingham AL 35233-1711, USA.
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40
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Topalis D, Gillemot S, Snoeck R, Andrei G. Thymidine kinase and protein kinase in drug-resistant herpesviruses: Heads of a Lernaean Hydra. Drug Resist Updat 2018; 37:1-16. [PMID: 29548479 DOI: 10.1016/j.drup.2018.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Herpesviruses thymidine kinase (TK) and protein kinase (PK) allow the activation of nucleoside analogues used in anti-herpesvirus treatments. Mutations emerging in these two genes often lead to emergence of drug-resistant strains responsible for life-threatening diseases in immunocompromised populations. In this review, we analyze the binding of different nucleoside analogues to the TK active site of the three α-herpesviruses [Herpes Simplex Virus 1 and 2 (HSV-1 and HSV-2) and Varicella-Zoster Virus (VZV)] and present the impact of known mutations on the structure of the viral TKs. Furthermore, models of β-herpesviruses [Human cytomegalovirus (HCMV) and human herpesvirus-6 (HHV-6)] PKs allow to link amino acid changes with resistance to ganciclovir and/or maribavir, an investigational chemotherapeutic used in patients with multidrug-resistant HCMV. Finally, we set the basis for the understanding of drug-resistance in γ-herpesviruses [Epstein-Barr virus (EBV) and Kaposi's sarcoma associated herpesvirus (KSHV)] TK and PK through the use of animal surrogate models.
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Affiliation(s)
- Dimitri Topalis
- Rega Institute for Medical Research, KU Leuven, Herestraat 49-box 1043, 3000 Leuven, Belgium.
| | - Sarah Gillemot
- Rega Institute for Medical Research, KU Leuven, Herestraat 49-box 1043, 3000 Leuven, Belgium.
| | - Robert Snoeck
- Rega Institute for Medical Research, KU Leuven, Herestraat 49-box 1043, 3000 Leuven, Belgium.
| | - Graciela Andrei
- Rega Institute for Medical Research, KU Leuven, Herestraat 49-box 1043, 3000 Leuven, Belgium.
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41
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Milbradt J, Sonntag E, Wagner S, Strojan H, Wangen C, Lenac Rovis T, Lisnic B, Jonjic S, Sticht H, Britt WJ, Schlötzer-Schrehardt U, Marschall M. Human Cytomegalovirus Nuclear Capsids Associate with the Core Nuclear Egress Complex and the Viral Protein Kinase pUL97. Viruses 2018; 10:v10010035. [PMID: 29342872 PMCID: PMC5795448 DOI: 10.3390/v10010035] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/05/2018] [Accepted: 01/10/2018] [Indexed: 02/07/2023] Open
Abstract
The nuclear phase of herpesvirus replication is regulated through the formation of regulatory multi-component protein complexes. Viral genomic replication is followed by nuclear capsid assembly, DNA encapsidation and nuclear egress. The latter has been studied intensely pointing to the formation of a viral core nuclear egress complex (NEC) that recruits a multimeric assembly of viral and cellular factors for the reorganization of the nuclear envelope. To date, the mechanism of the association of human cytomegalovirus (HCMV) capsids with the NEC, which in turn initiates the specific steps of nuclear capsid budding, remains undefined. Here, we provide electron microscopy-based data demonstrating the association of both nuclear capsids and NEC proteins at nuclear lamina budding sites. Specifically, immunogold labelling of the core NEC constituent pUL53 and NEC-associated viral kinase pUL97 suggested an intranuclear NEC-capsid interaction. Staining patterns with phospho-specific lamin A/C antibodies are compatible with earlier postulates of targeted capsid egress at lamina-depleted areas. Important data were provided by co-immunoprecipitation and in vitro kinase analyses using lysates from HCMV-infected cells, nuclear fractions, or infectious virions. Data strongly suggest that nuclear capsids interact with pUL53 and pUL97. Combined, the findings support a refined concept of HCMV nuclear trafficking and NEC-capsid interaction.
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Affiliation(s)
- Jens Milbradt
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen 91054, Germany.
| | - Eric Sonntag
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen 91054, Germany.
| | - Sabrina Wagner
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen 91054, Germany.
| | - Hanife Strojan
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen 91054, Germany.
| | - Christina Wangen
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen 91054, Germany.
| | - Tihana Lenac Rovis
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka 51000, Croatia.
| | - Berislav Lisnic
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka 51000, Croatia.
| | - Stipan Jonjic
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka 51000, Croatia.
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen 91054, Germany.
| | - William J Britt
- Departments of Pediatrics and Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | | | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen 91054, Germany.
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42
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Sonntag E, Milbradt J, Svrlanska A, Strojan H, Häge S, Kraut A, Hesse AM, Amin B, Sonnewald U, Couté Y, Marschall M. Protein kinases responsible for the phosphorylation of the nuclear egress core complex of human cytomegalovirus. J Gen Virol 2017; 98:2569-2581. [PMID: 28949903 DOI: 10.1099/jgv.0.000931] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Nuclear egress of herpesvirus capsids is mediated by a multi-component nuclear egress complex (NEC) assembled by a heterodimer of two essential viral core egress proteins. In the case of human cytomegalovirus (HCMV), this core NEC is defined by the interaction between the membrane-anchored pUL50 and its nuclear cofactor, pUL53. NEC protein phosphorylation is considered to be an important regulatory step, so this study focused on the respective role of viral and cellular protein kinases. Multiply phosphorylated pUL50 varieties were detected by Western blot and Phos-tag analyses as resulting from both viral and cellular kinase activities. In vitro kinase analyses demonstrated that pUL50 is a substrate of both PKCα and CDK1, while pUL53 can also be moderately phosphorylated by CDK1. The use of kinase inhibitors further illustrated the importance of distinct kinases for core NEC phosphorylation. Importantly, mass spectrometry-based proteomic analyses identified five major and nine minor sites of pUL50 phosphorylation. The functional relevance of core NEC phosphorylation was confirmed by various experimental settings, including kinase knock-down/knock-out and confocal imaging, in which it was found that (i) HCMV core NEC proteins are not phosphorylated solely by viral pUL97, but also by cellular kinases; (ii) both PKC and CDK1 phosphorylation are detectable for pUL50; (iii) no impact of PKC phosphorylation on NEC functionality has been identified so far; (iv) nonetheless, CDK1-specific phosphorylation appears to be required for functional core NEC interaction. In summary, our findings provide the first evidence that the HCMV core NEC is phosphorylated by cellular kinases, and that the complex pattern of NEC phosphorylation has functional relevance.
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Affiliation(s)
- Eric Sonntag
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Jens Milbradt
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Adriana Svrlanska
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Hanife Strojan
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Sigrun Häge
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Alexandra Kraut
- Université Grenoble Alpes, CEA, INSERM, BIG-BGE, F-38000 Grenoble, France
| | - Anne-Marie Hesse
- Université Grenoble Alpes, CEA, INSERM, BIG-BGE, F-38000 Grenoble, France
| | - Bushra Amin
- Department of Biology, Institute for Biochemistry, FAU, Erlangen, Germany
- Present address: Department of Chemistry, University of Pittsburgh, Pittsburgh 15260, PA, USA
| | - Uwe Sonnewald
- Department of Biology, Institute for Biochemistry, FAU, Erlangen, Germany
| | - Yohann Couté
- Université Grenoble Alpes, CEA, INSERM, BIG-BGE, F-38000 Grenoble, France
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Erlangen, Germany
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43
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Mitochondrial protein p32/HAPB1/gC1qR/C1qbp is required for efficient respiratory syncytial virus production. Biochem Biophys Res Commun 2017; 489:460-465. [DOI: 10.1016/j.bbrc.2017.05.171] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 05/29/2017] [Indexed: 11/21/2022]
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Hutterer C, Milbradt J, Hamilton S, Zaja M, Leban J, Henry C, Vitt D, Steingruber M, Sonntag E, Zeitträger I, Bahsi H, Stamminger T, Rawlinson W, Strobl S, Marschall M. Inhibitors of dual-specificity tyrosine phosphorylation-regulated kinases (DYRK) exert a strong anti-herpesviral activity. Antiviral Res 2017; 143:113-121. [PMID: 28400201 DOI: 10.1016/j.antiviral.2017.04.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/26/2017] [Accepted: 04/07/2017] [Indexed: 11/26/2022]
Abstract
Infection with human cytomegalovirus (HCMV) is a serious medical problem, particularly in immunocompromised individuals and neonates. The success of (val)ganciclovir therapy is hampered by low drug compatibility and induction of viral resistance. A novel strategy of antiviral treatment is based on the exploitation of cell-directed signaling, e. g. pathways with a known relevance for carcinogenesis and tumor drug development. Here we describe a principle for putative antiviral drugs based on targeting dual-specificity tyrosine phosphorylation-regulated kinases (DYRKs). DYRKs constitute an evolutionarily conserved family of protein kinases with key roles in the control of cell proliferation and differentiation. Members of the DYRK family are capable of phosphorylating a number of substrate proteins, including regulators of the cell cycle, e.g. DYRK1B can induce cell cycle arrest, a critical step for the regulation of HCMV replication. Here we provide first evidence for a critical role of DYRKs during viral replication and the high antiviral potential of DYRK inhibitors (SC84227, SC97202 and SC97208, Harmine and AZ-191). Using established replication assays for laboratory and clinically relevant strains of HCMV, concentration-dependent profiles of inhibition were obtained. Mean inhibitory concentrations (EC50) of 0.98 ± 0.08 μM/SC84227, 0.60 ± 0.02 μM/SC97202, 6.26 ± 1.64 μM/SC97208, 0.71 ± 0.019 μM/Harmine and 0.63 ± 0.23 μM/AZ-191 were determined with HCMV strain AD169-GFP for the infection of primary human fibroblasts. A first analysis of the mode of antiviral action suggested a block of viral replication at the early-late stage of HCMV gene expression. Moreover, rhesus macaque cytomegalovirus (RhCMV), varicella-zoster virus (VZV) and herpes simplex virus (HSV-1) showed a similarly high sensitivity to these compounds. Thus, we conclude that DYRK signaling represents a promising target pathway for the development of novel anti-herpesviral strategies.
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Affiliation(s)
- Corina Hutterer
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Germany.
| | - Jens Milbradt
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Germany
| | - Stuart Hamilton
- Serology and Virology Division, SEALS Microbiology Prince of Wales Hospital Randwick NSW 2013 and SOMS and BABS, University of NSW, Sydney, Australia
| | - Mirko Zaja
- 4SC Discovery GmbH, Martinsried, Germany
| | | | | | | | - Mirjam Steingruber
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Germany
| | - Eric Sonntag
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Germany
| | - Isabel Zeitträger
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Germany
| | - Hanife Bahsi
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Germany
| | - Thomas Stamminger
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Germany
| | - William Rawlinson
- Serology and Virology Division, SEALS Microbiology Prince of Wales Hospital Randwick NSW 2013 and SOMS and BABS, University of NSW, Sydney, Australia
| | | | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Germany.
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45
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Marschall M, Muller YA, Diewald B, Sticht H, Milbradt J. The human cytomegalovirus nuclear egress complex unites multiple functions: Recruitment of effectors, nuclear envelope rearrangement, and docking to nuclear capsids. Rev Med Virol 2017; 27. [PMID: 28664574 DOI: 10.1002/rmv.1934] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/19/2017] [Accepted: 05/22/2017] [Indexed: 01/07/2023]
Abstract
BACKGROUND Nuclear replication represents a common hallmark of herpesviruses achieved by a number of sequentially unrolled regulatory processes. A rate-limiting step is provided by nucleo-cytoplasmic capsid export, for which a defined multiregulatory protein complex, namely, the nuclear egress complex (NEC), is assembled comprising both viral and cellular components. The NEC regulates at least 3 aspects of herpesviral nuclear replication: (1) multimeric recruitment of NEC-associated effector proteins, (2) reorganization of the nuclear lamina and membranes, and (3) the docking to nuclear capsids. Here, we review published data and own experimental work that characterizes the NEC of HCMV and other herpesviruses. METHODS A systematic review of information on nuclear egress of HCMV compared to selected alpha-, beta-, and gamma-herpesviruses: proteomics-based approaches, high-resolution imaging techniques, and functional investigations. RESULTS A large number of reports on herpesviral NECs have been published during the last two decades, focusing on protein-protein interactions, nuclear localization, regulatory phosphorylation, and functional validation. The emerging picture provides an illustrated example of well-balanced and sophisticated protein networking in virus-host interaction. CONCLUSIONS Current evidence refined the view about herpesviral NECs. Datasets published for HCMV, murine CMV, herpes simplex virus, and Epstein-Barr virus illustrate the marked functional consistency in the way herpesviruses achieve nuclear egress. However, this compares with only limited sequence conservation of core NEC proteins and a structural conservation restricted to individual domains. The translational use of this information might help to define a novel antiviral strategy on the basis of NEC-directed small molecules.
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Affiliation(s)
- Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Yves A Muller
- Division of Biotechnology, Department of Biology, FAU, Erlangen, Germany
| | - Benedikt Diewald
- Division of Bioinformatics, Institute of Biochemistry, FAU, Erlangen, Germany
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, FAU, Erlangen, Germany
| | - Jens Milbradt
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), Erlangen, Germany
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46
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Jarosinski KW. Interindividual Spread of Herpesviruses. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2017; 223:195-224. [PMID: 28528445 DOI: 10.1007/978-3-319-53168-7_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Interindividual spread of herpesviruses is essential for the virus life cycle and maintenance in host populations. For most herpesviruses, the virus-host relationship is close, having coevolved over millions of years resulting in comparatively high species specificity. The mechanisms governing interindividual spread or horizontal transmission are very complex, involving conserved herpesviral and cellular proteins during the attachment, entry, replication, and egress processes of infection. Also likely, specific herpesviruses have evolved unique viral and cellular interactions during cospeciation that are dependent on their relationship. Multiple steps are required for interindividual spread including virus assembly in infected cells; release into the environment, followed by virus attachment; and entry into new hosts. Should any of these steps be compromised, transmission is rendered impossible. This review will focus mainly on the natural virus-host model of Marek's disease virus (MDV) in chickens in order to delineate important steps during interindividual spread.
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Affiliation(s)
- Keith W Jarosinski
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, 61802, USA.
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47
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Roller RJ, Baines JD. Herpesvirus Nuclear Egress. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2017; 223:143-169. [PMID: 28528443 DOI: 10.1007/978-3-319-53168-7_7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Herpesviruses assemble and package their genomes into capsids in the nucleus, but complete final assembly of the mature virion in the cell cytoplasm. This requires passage of the genome-containing capsid across the double-membrane nuclear envelope. Herpesviruses have evolved a mechanism that relies on a pair of conserved viral gene products to shuttle the capsids from the nucleus to the cytoplasm by way of envelopment and de-envelopment at the inner and outer nuclear membranes, respectively. This complex process requires orchestration of the activities of viral and cellular factors to alter the architecture of the nuclear membrane, select capsids at the appropriate stage for egress, and accomplish efficient membrane budding and fusion events. The last few years have seen major advances in our understanding of the membrane budding mechanism and helped clarify the roles of viral and cellular proteins in the other, more mysterious steps. Here, we summarize and place into context this recent research and, hopefully, clarify both the major advances and major gaps in our understanding.
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Affiliation(s)
- Richard J Roller
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Joel D Baines
- Kenneth F. Burns Chair in Veterinary Medicine, School of Veterinary Medicine, Skip Bertman Drive, Louisiana State University, Baton Rouge, LA, USA.
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48
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Extragenic Suppression of a Mutation in Herpes Simplex Virus 1 UL34 That Affects Lamina Disruption and Nuclear Egress. J Virol 2016; 90:10738-10751. [PMID: 27654296 DOI: 10.1128/jvi.01544-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 09/13/2016] [Indexed: 01/06/2023] Open
Abstract
Nuclear egress of herpesviruses is accompanied by changes in the architecture of the nuclear membrane and nuclear lamina that are thought to facilitate capsid access to the inner nuclear membrane (INM) and curvature of patches of the INM around the capsid during budding. Here we report the properties of a point mutant of pUL34 (Q163A) that fails to induce gross changes in nuclear architecture or redistribution of lamin A/C. The UL34(Q163A) mutant shows a roughly 100-fold defect in single-step growth, and it forms small plaques. This mutant has a defect in nuclear egress, and furthermore, it fails to disrupt nuclear shape or cause observable displacement of lamin A/C despite retaining the ability to recruit the pUS3 and PKC protein kinases and to mediate phosphorylation of emerin. Extragenic suppressors of the UL34(Q163A) phenotype were isolated, and all of them carry a single mutation of arginine 229 to leucine in UL31. Surprisingly, although this UL31 mutation largely restores virus replication, it does not correct the lamina disruption defect, suggesting that, in Vero cells, changes in nuclear shape and gross displacements of lamin A/C may facilitate but are unnecessary for nuclear egress. IMPORTANCE Herpesvirus nuclear egress is an essential and conserved process that requires close association of the viral capsid with the inner nuclear membrane and budding of the capsid into that membrane. Access to the nuclear membrane and tight curvature of that membrane are thought to require disruption of the nuclear lamina that underlies the inner nuclear membrane, and consistent with this idea, herpesvirus infection induces biochemical and architectural changes at the nuclear membrane. The significance of the nuclear membrane architectural changes is poorly characterized. The results presented here address that deficiency in our understanding and show that a combination of mutations in two of the viral nuclear egress factors results in a failure to accomplish at least two components of lamina disruption while still allowing relatively efficient viral replication, suggesting that changes in nuclear shape and displacement of lamins are not necessary for herpes simplex virus 1 (HSV-1) nuclear egress.
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49
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Kuan MI, O'Dowd JM, Fortunato EA. The absence of p53 during Human Cytomegalovirus infection leads to decreased UL53 expression, disrupting UL50 localization to the inner nuclear membrane, and thereby inhibiting capsid nuclear egress. Virology 2016; 497:262-278. [PMID: 27498409 PMCID: PMC5026620 DOI: 10.1016/j.virol.2016.07.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/18/2016] [Accepted: 07/19/2016] [Indexed: 01/10/2023]
Abstract
Our electron microscopy study (Kuan et al., 2016) found HCMV nuclear capsid egress was significantly reduced in p53 knockout cells (p53KOs), correlating with inhibited formation of infoldings of the inner nuclear membrane (IINMs). Molecular examination of these phenomena has found p53KOs expressed UL97 and phosphorylated lamins, however the lamina failed to remodel. The nuclear egress complex (NEC) protein UL50 was expressed in almost all cells. UL50 re-localized to the inner nuclear membrane (INM) in ~90% of wt cells, but only ~35% of p53KOs. UL53 expression was significantly reduced in p53KOs, and cells lacking UL50 nuclear staining, expressed no UL53. Re-introduction of p53 into p53KOs largely recovered UL53 positivity and UL50 nuclear re-localization. Nuclear rim located UL50/53 puncta, which co-localized with the major capsid protein, were largely absent in p53KOs. We believe these puncta were IINMs. In the absence of p53, UL53 expression was inhibited, disrupting formation of the NEC/IINMs, and reducing functional virion secretion.
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Affiliation(s)
- Man I Kuan
- Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, Moscow, ID, USA
| | - John M O'Dowd
- Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, Moscow, ID, USA
| | - Elizabeth A Fortunato
- Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, Moscow, ID, USA.
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Proteomic Interaction Patterns between Human Cyclins, the Cyclin-Dependent Kinase Ortholog pUL97 and Additional Cytomegalovirus Proteins. Viruses 2016; 8:v8080219. [PMID: 27548200 PMCID: PMC4997581 DOI: 10.3390/v8080219] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 07/25/2016] [Accepted: 08/02/2016] [Indexed: 01/13/2023] Open
Abstract
The human cytomegalovirus (HCMV)-encoded cyclin-dependent kinase (CDK) ortholog pUL97 associates with human cyclin B1 and other types of cyclins. Here, the question was addressed whether cyclin interaction of pUL97 and additional viral proteins is detectable by mass spectrometry-based approaches. Proteomic data were validated by coimmunoprecipitation (CoIP), Western blot, in vitro kinase and bioinformatic analyses. Our findings suggest that: (i) pUL97 shows differential affinities to human cyclins; (ii) pUL97 inhibitor maribavir (MBV) disrupts the interaction with cyclin B1, but not with other cyclin types; (iii) cyclin H is identified as a new high-affinity interactor of pUL97 in HCMV-infected cells; (iv) even more viral phosphoproteins, including all known substrates of pUL97, are detectable in the cyclin-associated complexes; and (v) a first functional validation of pUL97-cyclin B1 interaction, analyzed by in vitro kinase assay, points to a cyclin-mediated modulation of pUL97 substrate preference. In addition, our bioinformatic analyses suggest individual, cyclin-specific binding interfaces for pUL97-cyclin interaction, which could explain the different strengths of interactions and the selective inhibitory effect of MBV on pUL97-cyclin B1 interaction. Combined, the detection of cyclin-associated proteins in HCMV-infected cells suggests a complex pattern of substrate phosphorylation and a role of cyclins in the fine-modulation of pUL97 activities.
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