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Corda PO, Bollen M, Ribeiro D, Fardilha M. Emerging roles of the Protein Phosphatase 1 (PP1) in the context of viral infections. Cell Commun Signal 2024; 22:65. [PMID: 38267954 PMCID: PMC10807198 DOI: 10.1186/s12964-023-01468-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 12/30/2023] [Indexed: 01/26/2024] Open
Abstract
Protein Phosphatase 1 (PP1) is a major serine/threonine phosphatase in eukaryotes, participating in several cellular processes and metabolic pathways. Due to their low substrate specificity, PP1's catalytic subunits do not exist as free entities but instead bind to Regulatory Interactors of Protein Phosphatase One (RIPPO), which regulate PP1's substrate specificity and subcellular localization. Most RIPPOs bind to PP1 through combinations of short linear motifs (4-12 residues), forming highly specific PP1 holoenzymes. These PP1-binding motifs may, hence, represent attractive targets for the development of specific drugs that interfere with a subset of PP1 holoenzymes. Several viruses exploit the host cell protein (de)phosphorylation machinery to ensure efficient virus particle formation and propagation. While the role of many host cell kinases in viral life cycles has been extensively studied, the targeting of phosphatases by viral proteins has been studied in less detail. Here, we compile and review what is known concerning the role of PP1 in the context of viral infections and discuss how it may constitute a putative host-based target for the development of novel antiviral strategies.
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Affiliation(s)
- Pedro O Corda
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Mathieu Bollen
- Department of Cellular and Molecular Medicine, Laboratory of Biosignaling & Therapeutics, Katholieke Universiteit Leuven, Louvain, Belgium
| | - Daniela Ribeiro
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal.
| | - Margarida Fardilha
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal.
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2
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Henke W, Waisner H, Arachchige SP, Kalamvoki M, Stephens E. The envelope proteins from SARS-CoV-2 and SARS-CoV potently reduce the infectivity of human immunodeficiency virus type 1 (HIV-1). Retrovirology 2022; 19:25. [PMID: 36403071 PMCID: PMC9675205 DOI: 10.1186/s12977-022-00611-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 11/01/2022] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Viroporins are virally encoded ion channels involved in virus assembly and release. Human immunodeficiency virus type 1 (HIV-1) and influenza A virus encode for viroporins. The human coronavirus SARS-CoV-2 encodes for at least two viroporins, a small 75 amino acid transmembrane protein known as the envelope (E) protein and a larger 275 amino acid protein known as Orf3a. Here, we compared the replication of HIV-1 in the presence of four different β-coronavirus E proteins. RESULTS We observed that the SARS-CoV-2 and SARS-CoV E proteins reduced the release of infectious HIV-1 yields by approximately 100-fold while MERS-CoV or HCoV-OC43 E proteins restricted HIV-1 infectivity to a lesser extent. Mechanistically, neither reverse transcription nor mRNA synthesis was involved in the restriction. We also show that all four E proteins caused phosphorylation of eIF2-α at similar levels and that lipidation of LC3-I could not account for the differences in restriction. However, the level of caspase 3 activity in transfected cells correlated with HIV-1 restriction in cells. Finally, we show that unlike the Vpu protein of HIV-1, the four E proteins did not significantly down-regulate bone marrow stromal cell antigen 2 (BST-2). CONCLUSIONS The results of this study indicate that while viroporins from homologous viruses can enhance virus release, we show that a viroporin from a heterologous virus can suppress HIV-1 protein synthesis and release of infectious virus.
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Affiliation(s)
- Wyatt Henke
- Department of Microbiology, Molecular Genetics and ImmunologyUniversity of Kansas Medical Center, 2000 Hixon Hall 3901 Rainbow Blvd, Kansas, KS 66160 USA
| | - Hope Waisner
- Department of Microbiology, Molecular Genetics and ImmunologyUniversity of Kansas Medical Center, 2000 Hixon Hall 3901 Rainbow Blvd, Kansas, KS 66160 USA
| | - Sachith Polpitiya Arachchige
- Department of Microbiology, Molecular Genetics and ImmunologyUniversity of Kansas Medical Center, 2000 Hixon Hall 3901 Rainbow Blvd, Kansas, KS 66160 USA
| | - Maria Kalamvoki
- Department of Microbiology, Molecular Genetics and ImmunologyUniversity of Kansas Medical Center, 2000 Hixon Hall 3901 Rainbow Blvd, Kansas, KS 66160 USA
| | - Edward Stephens
- Department of Microbiology, Molecular Genetics and ImmunologyUniversity of Kansas Medical Center, 2000 Hixon Hall 3901 Rainbow Blvd, Kansas, KS 66160 USA
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3
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Paradoxical effects of DNA tumor virus oncogenes on epithelium-derived tumor cell fate during tumor progression and chemotherapy response. Signal Transduct Target Ther 2021; 6:408. [PMID: 34836940 PMCID: PMC8626493 DOI: 10.1038/s41392-021-00787-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 09/23/2021] [Accepted: 10/11/2021] [Indexed: 12/13/2022] Open
Abstract
Epstein-Barr virus (EBV) and human papillomavirus (HPV) infection is the risk factors for nasopharyngeal carcinoma and cervical carcinoma, respectively. However, clinical analyses demonstrate that EBV or HPV is associated with improved response of patients, although underlying mechanism remains unclear. Here, we reported that the oncoproteins of DNA viruses, such as LMP1 of EBV and E7 of HPV, inhibit PERK activity in cancer cells via the interaction of the viral oncoproteins with PERK through a conserved motif. Inhibition of PERK led to increased level of reactive oxygen species (ROS) that promoted tumor and enhanced the efficacy of chemotherapy in vivo. Consistently, disruption of viral oncoprotein-PERK interactions attenuated tumor growth and chemotherapy in both cancer cells and tumor-bearing mouse models. Our findings uncovered a paradoxical effect of DNA tumor virus oncoproteins on tumors and highlighted that targeting PERK might be an attractive strategy for the treatment of NPC and cervical carcinoma.
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4
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Oncolytic HSV: Underpinnings of Tumor Susceptibility. Viruses 2021; 13:v13071408. [PMID: 34372614 PMCID: PMC8310378 DOI: 10.3390/v13071408] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/03/2021] [Accepted: 07/14/2021] [Indexed: 12/12/2022] Open
Abstract
Oncolytic herpes simplex virus (oHSV) is a therapeutic modality that has seen substantial success for the treatment of cancer, though much remains to be improved. Commonly attenuated through the deletion or alteration of the γ134.5 neurovirulence gene, the basis for the success of oHSV relies in part on the malignant silencing of cellular pathways critical for limiting these viruses in healthy host tissue. However, only recently have the molecular mechanisms underlying the success of these treatments begun to emerge. Further clarification of these mechanisms can strengthen rational design approaches to develop the next generation of oHSV. Herein, we review our current understanding of the molecular basis for tumor susceptibility to γ134.5-attenuated oHSV, with particular focus on the malignant suppression of nucleic acid sensing, along with strategies meant to improve the clinical efficacy of these therapeutic viruses.
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5
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Liu X, Ma Y, Voss K, van Gent M, Chan YK, Gack MU, Gale M, He B. The herpesvirus accessory protein γ134.5 facilitates viral replication by disabling mitochondrial translocation of RIG-I. PLoS Pathog 2021; 17:e1009446. [PMID: 33770145 PMCID: PMC7996975 DOI: 10.1371/journal.ppat.1009446] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 03/02/2021] [Indexed: 12/13/2022] Open
Abstract
RIG-I and MDA5 are cytoplasmic RNA sensors that mediate cell intrinsic immunity against viral pathogens. While it has been well-established that RIG-I and MDA5 recognize RNA viruses, their interactive network with DNA viruses, including herpes simplex virus 1 (HSV-1), remains less clear. Using a combination of RNA-deep sequencing and genetic studies, we show that the γ134.5 gene product, a virus-encoded virulence factor, enables HSV growth by neutralization of RIG-I dependent restriction. When expressed in mammalian cells, HSV-1 γ134.5 targets RIG-I, which cripples cytosolic RNA sensing and subsequently suppresses antiviral gene expression. Rather than inhibition of RIG-I K63-linked ubiquitination, the γ134.5 protein precludes the assembly of RIG-I and cellular chaperone 14-3-3ε into an active complex for mitochondrial translocation. The γ134.5-mediated inhibition of RIG-I-14-3-3ε binding abrogates the access of RIG-I to mitochondrial antiviral-signaling protein (MAVS) and activation of interferon regulatory factor 3. As such, unlike wild type virus HSV-1, a recombinant HSV-1 in which γ134.5 is deleted elicits efficient cytokine induction and replicates poorly, while genetic ablation of RIG-I expression, but not of MDA5 expression, rescues viral growth. Collectively, these findings suggest that viral suppression of cytosolic RNA sensing is a key determinant in the evolutionary arms race of a large DNA virus and its host.
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Affiliation(s)
- Xing Liu
- Department of Microbiology and Immunology University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - Yijie Ma
- Department of Microbiology and Immunology University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - Kathleen Voss
- Center for Innate Immunity and Immune Disease, Department Immunology, University of Washington, Seattle, Washington, United States of America
| | - Michiel van Gent
- Florida Research and Innovation Center, Cleveland Clinic, Port Saint Lucie, Florida, United States of America
- Department of Microbiology, The University of Chicago, Illinois, United States of America
| | - Ying Kai Chan
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States of America
| | - Michaela U. Gack
- Florida Research and Innovation Center, Cleveland Clinic, Port Saint Lucie, Florida, United States of America
- Department of Microbiology, The University of Chicago, Illinois, United States of America
| | - Michael Gale
- Center for Innate Immunity and Immune Disease, Department Immunology, University of Washington, Seattle, Washington, United States of America
| | - Bin He
- Department of Microbiology and Immunology University of Illinois College of Medicine, Chicago, Illinois, United States of America
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6
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Bernstein DI, Cardin RD, Smith GA, Pickard GE, Sollars PJ, Dixon DA, Pasula R, Bravo FJ. The R2 non-neuroinvasive HSV-1 vaccine affords protection from genital HSV-2 infections in a guinea pig model. NPJ Vaccines 2020; 5:104. [PMID: 33298966 PMCID: PMC7648054 DOI: 10.1038/s41541-020-00254-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 10/06/2020] [Indexed: 02/01/2023] Open
Abstract
Herpes simplex virus (HSV) infections are common and can cause severe illness but no vaccine is currently available. The recent failure of subunit HSV vaccines has highlighted the need for vaccines that present a diverse array of antigens, including the development of next-generation live-attenuated vaccines. However, most attenuated HSV strains propagate poorly, limiting their ability to elicit protective immune responses. A live-attenuated vaccine that replicates in non-neural tissue but is ablated for transmission into the nervous system may elicit protective immune responses without evoking neurologic complications or establishing life-long infections. Initial studies of R2, a live-attenuated vaccine that is engineered to be unable to invade the nervous system, used the guinea pig genital HSV model to evaluate the ability of R2 to replicate at the site of inoculation, cause disease and infect neural tissues. R2 was then evaluated as a vaccine using three routes of inoculation: intramuscular (IM), intradermal (ID) and intravaginal (IVag) and compared to IM administered gD2+MPL/Alum vaccine in the same model. R2 replicated in the genital tract but did not produce acute or recurrent disease and did not infect the neural tissue. The R2 vaccine-induced neutralizing antibody and decreased the severity of acute and recurrent HSV-2 disease as well as recurrent shedding. The ID route was the most effective. ID administered R2 was more effective than gD2+MPL/Alum at inducing neutralizing antibody, suppressing acute disease, and acute vaginal virus replication. R2 was especially more effective at reducing recurrent virus shedding, the most common source of HSV transmission. The live-attenuated prophylactic HSV vaccine, R2, was effective in the guinea pig model of genital HSV-2 especially when administered by the ID route. The use of live-attenuated HSV vaccines that robustly replicate in mucosal tissues but are ablated for neuroinvasion offers a promising approach for HSV vaccines.
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Affiliation(s)
- David I Bernstein
- Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA.
| | - Rhonda D Cardin
- School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Gregory A Smith
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Gary E Pickard
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, USA
| | - Patricia J Sollars
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, USA
| | - David A Dixon
- Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - Rajamouli Pasula
- Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - Fernando J Bravo
- Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
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7
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Humeau J, Leduc M, Cerrato G, Loos F, Kepp O, Kroemer G. Phosphorylation of eukaryotic initiation factor-2α (eIF2α) in autophagy. Cell Death Dis 2020; 11:433. [PMID: 32513922 PMCID: PMC7280501 DOI: 10.1038/s41419-020-2642-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 05/19/2020] [Accepted: 05/25/2020] [Indexed: 01/12/2023]
Abstract
The integrated stress response is characterized by the phosphorylation of eukaryotic initiation factor-2α (eIF2α) on serine 51 by one out of four specific kinases (EIF2AK1 to 4). Here we provide three series of evidence suggesting that macroautophagy (to which we refer to as autophagy) induced by a variety of distinct pharmacological agents generally requires this phosphorylation event. First, the induction of autophagic puncta by various distinct compounds was accompanied by eIF2α phosphorylation on serine 51. Second, the modulation of autophagy by >30 chemically unrelated agents was partially inhibited in cells expressing a non-phosphorylable (S51A) mutant of eIF2α or lacking all four eIF2α kinases, although distinct kinases were involved in the response to different autophagy inducers. Third, inhibition of eIF2α phosphatases was sufficient to stimulate autophagy. In synthesis, it appears that eIF2α phosphorylation is a central event for the stimulation of autophagy.
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Affiliation(s)
- Juliette Humeau
- Equipe Labellisée par la Ligue Contre le Cancer, Université de Paris, Sorbonne Université, INSERM UMR1138, Centre de Recherche des Cordeliers, Paris, France.,Metabolomics and Cell Biology Platforms, Gustave Roussy, Villejuif, France.,Faculty of Medicine, Université Paris Sud, Paris Saclay, Kremlin Bicêtre, France
| | - Marion Leduc
- Equipe Labellisée par la Ligue Contre le Cancer, Université de Paris, Sorbonne Université, INSERM UMR1138, Centre de Recherche des Cordeliers, Paris, France.,Metabolomics and Cell Biology Platforms, Gustave Roussy, Villejuif, France
| | - Giulia Cerrato
- Equipe Labellisée par la Ligue Contre le Cancer, Université de Paris, Sorbonne Université, INSERM UMR1138, Centre de Recherche des Cordeliers, Paris, France.,Metabolomics and Cell Biology Platforms, Gustave Roussy, Villejuif, France.,Faculty of Medicine, Université Paris Sud, Paris Saclay, Kremlin Bicêtre, France
| | - Friedemann Loos
- Equipe Labellisée par la Ligue Contre le Cancer, Université de Paris, Sorbonne Université, INSERM UMR1138, Centre de Recherche des Cordeliers, Paris, France.,Metabolomics and Cell Biology Platforms, Gustave Roussy, Villejuif, France
| | - Oliver Kepp
- Equipe Labellisée par la Ligue Contre le Cancer, Université de Paris, Sorbonne Université, INSERM UMR1138, Centre de Recherche des Cordeliers, Paris, France. .,Metabolomics and Cell Biology Platforms, Gustave Roussy, Villejuif, France.
| | - Guido Kroemer
- Equipe Labellisée par la Ligue Contre le Cancer, Université de Paris, Sorbonne Université, INSERM UMR1138, Centre de Recherche des Cordeliers, Paris, France. .,Metabolomics and Cell Biology Platforms, Gustave Roussy, Villejuif, France. .,Suzhou Institute for Systems Medicine, Chinese Academy of Medical Sciences, Suzhou, China. .,Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France. .,Department of Women's and Children's Health, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden.
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8
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Selective Editing of Herpes Simplex Virus 1 Enables Interferon Induction and Viral Replication That Destroy Malignant Cells. J Virol 2019; 93:JVI.01761-18. [PMID: 30404809 DOI: 10.1128/jvi.01761-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 10/28/2018] [Indexed: 12/17/2022] Open
Abstract
Oncolytic herpes simplex virus 1 (HSV-1), devoid of the γ134.5 gene, exerts antitumor activities. However, the oncolytic effects differ, ranging from pronounced to little responses. Although viral and host factors are involved, much remains to be deciphered. Here we report that engineered HSV-1 ΔN146, bearing amino acids 147 to 263 of γ134.5, replicates competently in and lyses malignant cells refractory to the γ134.5 null mutant. Upon infection, ΔN146 precludes phosphorylation of translation initiation factor eIF2α (α subunit of eukaryotic initiation factor 2), ensuring viral protein synthesis. On the other hand, ΔN146 activates interferon (IFN) regulatory factor 3 (IRF3) and IFN expression, known to prime immunity against virus and tumor. Nevertheless, ΔN146 exhibits sustained replication even exposed to exogenous IFN-α. In a 4T1 tumor model, ΔN146 markedly reduces tumor growth and metastasis formation. This coincides with viral replication or T cell infiltration in primary tumors. ΔN146 is undetectable in normal tissues in vivo Targeted HSV-1 editing results in a unique antineoplastic agent that enables inflammation without major interference of viral growth within tumor cells.IMPORTANCE Oncolytic herpes simplex virus 1 is a promising agent for cancer immunotherapy. Due to a complex virus-host interaction, less is clear about what viral signature(s) constitutes a potent oncolytic backbone. Through molecular or genetic dissection, we showed that selective editing of the γ134.5 gene enables viral replication in malignant cells, activation of transcription factor IRF3, and subsequent induction of type I IFN. This translates into profoundly reduced primary tumor growth and metastasis burden in an aggressive breast carcinoma model in vivo Our work reveals a distinct oncolytic platform that is amendable for further development.
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9
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Herpes Simplex Virus 1 γ 134.5 Protein Inhibits STING Activation That Restricts Viral Replication. J Virol 2018; 92:JVI.01015-18. [PMID: 30045990 DOI: 10.1128/jvi.01015-18] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 07/19/2018] [Indexed: 11/20/2022] Open
Abstract
The γ134.5 gene of herpes simplex virus 1 (HSV-1) encodes a virulence factor that promotes viral pathogenesis. Although it perturbs TANK-binding kinase 1 (TBK1) in the complex network of innate immune pathways, the underlying mechanism is obscure. Here we report that HSV-1 γ134.5 targets stimulator of interferon genes (STING) in the intracellular DNA recognition pathway that regulates TBK1 activation. In virus-infected cells the γ134.5 protein associates with and inactivates STING, which leads to downregulation of interferon regulatory factor 3 (IRF3) and IFN responses. Importantly, HSV-1 γ134.5 disrupts translocation of STING from the endoplasmic reticulum to Golgi apparatus, a process necessary to prime cellular immunity. Deletion of γ134.5 or its amino-terminal domain from HSV-1 abolishes the observed inhibitory activities. Consistently, an HSV mutant that lacks functional γ134.5 replicated less efficiently in STING+/+ than in STING-/- mouse embryonic fibroblasts. Moreover, reconstituted expression of human STING in the STING-/- cells activated IRF3 and reduced viral growth. These results suggest that control of the DNA sensing pathway by γ134.5 is advantageous to HSV infection.IMPORTANCE Viral inhibition of innate immunity contributes to herpes simplex virus pathogenesis. Although this complex process involves multiple factors, the underlying events remain unclear. We demonstrate that an HSV virulence factor γ134.5 precludes the activation of STING, a central adaptor in the intracellular DNA sensing pathway. Upon HSV infection, this viral protein engages with and inactivates STING. Consequently, it compromises host immunity and facilitates HSV replication. These observations uncover an HSV mechanism that is likely to mediate viral virulence.
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10
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Herpes Simplex Virus 1 Induces Phosphorylation and Reorganization of Lamin A/C through the γ134.5 Protein That Facilitates Nuclear Egress. J Virol 2016; 90:10414-10422. [PMID: 27630226 DOI: 10.1128/jvi.01392-16] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 09/06/2016] [Indexed: 12/11/2022] Open
Abstract
Herpes simplex virus 1 (HSV-1) remodels nuclear membranes during virus egress. Although the UL31 and UL34 proteins control nucleocapsid transit in infected cells, the molecular interactions required for their function are unclear. Here we report that the γ134.5 gene product of HSV-1 facilitates nucleocapsid release to the cytoplasm through bridging the UL31/UL34 complex, cellular p32, and protein kinase C. Unlike wild-type virus, an HSV mutant devoid of γ134.5 or its amino terminus is crippled for viral growth and release. This is attributable to a defect in virus nuclear egress. In infected cells, wild-type virus recruits protein kinase C to the nuclear membrane and triggers its activation, whereas the γ134.5 mutants fail to exert such an effect. Accordingly, the γ134.5 mutants are unable to induce phosphorylation and reorganization of lamin A/C. When expressed in host cells γ134.5 targets p32 and protein kinase C. Meanwhile, it communicates with the UL31/UL34 complex through UL31. Deletion of the amino terminus from γ134.5 disrupts its activity. These results suggest that disintegration of the nuclear lamina mediated by γ134.5 promotes HSV replication. IMPORTANCE HSV nuclear egress is a key step that determines the outcome of viral infection. While the nuclear egress complex mediates capsid transit across the nuclear membrane, the regulatory components are not clearly defined in virus-infected cells. We report that the γ134.5 gene product, a virulence factor of HSV-1, facilitates nuclear egress cooperatively with cellular p32, protein kinase C, and the nuclear egress complex. This work highlights a viral mechanism that may contribute to the pathogenesis of HSV infection.
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11
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Wilcox DR, Longnecker R. The Herpes Simplex Virus Neurovirulence Factor γ34.5: Revealing Virus-Host Interactions. PLoS Pathog 2016; 12:e1005449. [PMID: 26964062 PMCID: PMC4786305 DOI: 10.1371/journal.ppat.1005449] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Douglas R. Wilcox
- Department of Microbiology and Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Richard Longnecker
- Department of Microbiology and Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
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12
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HSV targeting of the host phosphatase PP1α is required for disseminated disease in the neonate and contributes to pathogenesis in the brain. Proc Natl Acad Sci U S A 2015; 112:E6937-44. [PMID: 26621722 DOI: 10.1073/pnas.1513045112] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Newborns are significantly more susceptible to severe disease after infection with herpes simplex virus (HSV) compared with adults, with differences in the host response implicated as a major factor. To understand host response differences between these age groups, we investigated the shutoff of protein synthesis by the host and the retargeting of host phosphatase PP1α by the HSV-1 protein γ34.5 for reversal of translational arrest. In a murine newborn model of viral dissemination, infection with the HSV-1 mutant for PP1α binding resulted in complete absence of disease. PP1α-binding mutant HSV-1 replicated in visceral organs early after inoculation, demonstrating that HSV-1 replication requires PP1α-targeting only later in infection. Newborn mice deficient in type I IFN signaling partially rescued the virulence of the PP1α-binding mutant virus, suggesting an IFN-independent role for eIF2α kinases during infection. When we investigated the contribution of PP1α targeting to pathogenesis in the brain, we found that the inability of HSV-1 to bind PP1α increased survival time in both newborn and adult mice. Unlike disseminated disease, type I IFN signaling in the brain was required to attenuate disease following PP1α-mutant virus infection. Furthermore, pharmacologic inhibition of eIF2α dephosphorylation reduced HSV-1 replication in a brain slice culture model of encephalitis. Our findings reveal age-dependent differences in γ34.5 function and tissue-specific reliance on the type I IFN response for protection from HSV disease. These results define an important role for γ34.5 in neonatal infections in contrast to other studies indicating that the autophagy-inhibiting function of γ34.5 is dispensable for pathogenesis in the newborn brain.
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13
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Davis KL, Korom M, Morrison LA. Herpes simplex virus 2 ICP34.5 confers neurovirulence by regulating the type I interferon response. Virology 2014; 468-470:330-339. [PMID: 25238641 DOI: 10.1016/j.virol.2014.08.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 06/04/2014] [Accepted: 08/19/2014] [Indexed: 02/04/2023]
Abstract
The γ34.5 gene of herpes simplex virus (HSV) 2 encodes ICP34.5, which enhances HSV-2 neurovirulence by an unknown mechanism. We found that an HSV-2 γ34.5-null mutant (γ34.5(-/-)) replicated less robustly than its rescue virus (γ34.5R) in wild-type mouse embryo fibroblasts (MEFs), and in cells primed with IFNβ. Increased eIF2α phosphorylation correlated with γ34.5(-/-) attenuation. However, γ34.5(-/-) achieved titers equivalent to γ34.5R in MEFs lacking the type I IFN receptor (IFNα/βR(-/-)) or lacking protein kinase R. γ34.5(-/-) also replicated poorly in the vaginal mucosa of wild-type mice, caused little genital inflammation, and spread to the nervous system at lower levels compared to γ34.5R. In IFNα/βR(-/-) mice, however, γ34.5(-/-) regained the capacity to replicate and cause disease equivalent to γ34.5R after intravaginal infection or direct inoculation into the central nervous system. Thus, the capacity of HSV-2 ICP34.5 to interdict the type I IFN response in vivo largely determines its neurovirulence.
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Affiliation(s)
- Katie L Davis
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, 1100 South Grand Boulevard, St. Louis, MO 63104, USA
| | - Maria Korom
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, 1100 South Grand Boulevard, St. Louis, MO 63104, USA
| | - Lynda A Morrison
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, 1100 South Grand Boulevard, St. Louis, MO 63104, USA.
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14
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Up to four distinct polypeptides are produced from the γ34.5 open reading frame of herpes simplex virus 2. J Virol 2014; 88:11284-96. [PMID: 25031346 DOI: 10.1128/jvi.01284-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The herpes simplex virus 1 (HSV-1) ICP34.5 protein strongly influences neurovirulence and regulates several cellular antiviral responses. Despite the clinical importance of HSV-2, relatively little is known about its ICP34.5 ortholog. We found that HSV-2 produces up to four distinct forms of ICP34.5 in infected cells: a full-length protein, one shorter form sharing the N terminus, and two shorter forms sharing the C terminus. These forms appeared with similar kinetics and accumulated in cells over much of the replication cycle. We confirmed that the N-terminal form is translated from the primary unspliced transcript to a stop codon within the intron unique to HSV-2 γ34.5. We found that the N-terminal form was produced in a variety of cell types and by 9 of 10 clinical isolates. ICP27 influenced but was not required for expression of the N-terminal form. Western blotting and reverse transcription-PCR indicated the C-terminal forms did not contain the N terminus and were not products of alternative splicing or internal transcript initiation. Expression plasmids encoding methionine at amino acids 56 and 70 generated products that comigrated in SDS-PAGE with the C1 and C2 forms, respectively, and mutation of these sites abolished C1 and C2. Using a recombinant HSV-2 encoding hemagglutinin (HA)-tagged ICP34.5, we demonstrated that the C-terminal forms were also produced during infection of many human and mouse cell types but were not detectable in mouse primary neurons. The protein diversity generated from the HSV-2 γ34.5 open reading frame implies additional layers of cellular regulation through potential independent activities associated with the various forms of ICP34.5. IMPORTANCE The herpes simplex virus 1 (HSV-1) protein ICP34.5, encoded by the γ34.5 gene, interferes with several host defense mechanisms by binding cellular proteins that would otherwise stimulate the cell's autophagic, translational-arrest, and type I interferon responses to virus infection. ICP34.5 also plays a crucial role in determining the severity of nervous system infections with HSV-1 and HSV-2. The HSV-2 γ34.5 gene contains an intron not present in HSV-1 γ34.5. A shorter N-terminal form of HSV-2 ICP34.5 can be translated from the unspliced γ34.5 mRNA. Here, we show that two additional forms consisting of the C-terminal portion of ICP34.5 are generated in infected cells. Production of these N- and C-terminal forms is highly conserved among HSV-2 strains, including many clinical isolates, and they are broadly expressed in several cell types, but not mouse primary neurons. Multiple ICP34.5 polypeptides add additional complexity to potential functional interactions influencing HSV-2 neurovirulence.
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Murine gammaherpesvirus 68 encoding open reading frame 11 targets TANK binding kinase 1 to negatively regulate the host type I interferon response. J Virol 2014; 88:6832-46. [PMID: 24696485 DOI: 10.1128/jvi.03460-13] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Upon viral infection, type I interferons, such as alpha and beta interferon (IFN-α and IFN-β, respectively), are rapidly induced and activate multiple antiviral genes, thereby serving as the first line of host defense. Many DNA and RNA viruses counteract the host interferon system by modulating the production of IFNs. In this study, we report that murine gammaherpesvirus 68 (MHV-68), a double-stranded DNA virus, encodes open reading frame 11 (ORF11), a novel immune modulator, to block IFN-β production. ORF11-deficient recombinant viruses induced more IFN-β production in fibroblast and macrophage cells than the MHV-68 wild type or a marker rescue virus. MHV-68 ORF11 decreased IFN-β promoter activation by various factors, the signaling of which converges on TBK1-IRF3 activation. MHV-68 ORF11 directly interacted with both overexpressed and endogenous TBK1 but not with IRF3. Physical interactions between ORF11 and endogenous TBK1 were further confirmed during virus replication in fibroblasts using a recombinant virus expressing FLAG-ORF11. ORF11 efficiently reduced interaction between TBK1 and IRF3 and subsequently inhibited activation of IRF3, thereby negatively regulating IFN-β production. Our domain-mapping study showed that the central domain of ORF11 was responsible for both TBK1 binding and inhibition of IFN-β induction, while the kinase domain of TBK1 was sufficient for ORF11 binding. Taken together, these results suggest a mechanism underlying inhibition of IFN-β production by a gammaherpesvirus and highlight the importance of TBK1 in DNA virus replication. IMPORTANCE Gammaherpesviruses are important human pathogens, as they are associated with various kinds of tumors. Upon virus infection, the type I interferon pathway is activated by a series of signaling molecules and stimulates antiviral gene expression. To subvert such interferon antiviral responses, viruses are equipped with multiple factors that can inhibit its critical steps. In this study, we took an unbiased genomic approach using a mutant library of murine gammaherpesvirus 68 to screen a novel viral immune modulator that negatively regulates the type I interferon pathway and identified ORF11 as a strong candidate. ORF11-deficient virus infection produced more interferon than the wild type in both fibroblasts and macrophages. During virus replication, ORF11 directly bound to TBK1, a key regulatory protein in the interferon pathway, and inhibited TBK1-mediated interferon production. Our results highlight a crucial role of TBK1 in controlling DNA virus infection and a viral strategy to curtail host surveillance.
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Ma Y, He B. Recognition of herpes simplex viruses: toll-like receptors and beyond. J Mol Biol 2013; 426:1133-47. [PMID: 24262390 DOI: 10.1016/j.jmb.2013.11.012] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/31/2013] [Accepted: 11/13/2013] [Indexed: 12/25/2022]
Abstract
Herpes simplex viruses (HSVs) are human pathogens that establish lytic and latent infections. Reactivation from latency occurs intermittently, which represents a lifelong source of recurrent infection. In this complex process, HSV triggers and neutralizes innate immunity. Therefore, a dynamic equilibrium between HSV and the innate immune system determines the outcome of viral infection. Detection of HSV involves pathogen recognition receptors that include Toll-like receptors, retinoic acid-inducible gene I-like receptors, and cytosolic DNA sensors. Moreover, innate components or pathways exist to sense membrane fusion upon viral entry into host cells. Consequently, this surveillance network activates downstream transcription factors, leading to the induction of type I interferon and inflammatory cytokines. Not surprisingly, with the capacity to establish chronic infection HSV has evolved strategies that modulate or evade innate immunity. In this review, we describe recent advances pertinent to the interplay of HSV and the induction of innate immunity mediated by pathogen recognition receptors or pathways.
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Affiliation(s)
- Yijie Ma
- Department of Microbiology and Immunology, College of Medicine, University of Illinois, Chicago, IL 60612, USA
| | - Bin He
- Department of Microbiology and Immunology, College of Medicine, University of Illinois, Chicago, IL 60612, USA.
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Inhibition of the host translation shutoff response by herpes simplex virus 1 triggers nuclear envelope-derived autophagy. J Virol 2013; 87:3990-7. [PMID: 23365427 DOI: 10.1128/jvi.02974-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Macroautophagy is a cellular pathway that degrades intracellular pathogens and contributes to antigen presentation. Herpes simplex virus 1 (HSV-1) infection triggers both macroautophagy and an additional form of autophagy that uses the nuclear envelope as a source of membrane. The present study constitutes the first in-depth analysis of nuclear envelope-derived autophagy (NEDA). We established LC3a as a marker that allowed us to distinguish between NEDA and macroautophagy in both immunofluorescence and flow cytometry. NEDA was observed in many different cell types, indicating that it is a general response to HSV-1 infection. This autophagic pathway is known to depend on the viral protein γ34.5, which can inhibit macroautophagy via binding to beclin-1. Using mutant viruses, we were able to show that binding of beclin-1 by γ34.5 had no effect on NEDA, demonstrating that NEDA is regulated differently than macroautophagy. Instead, NEDA was triggered in response to γ34.5 binding to protein phosphatase 1α, an interaction used by the virus to prevent host cells from shutting off protein translation. NEDA was not triggered when late viral protein production was inhibited with acyclovir or hippuristanol, indicating that the accumulation of these proteins might stress infected cells. Interestingly, expression of the late viral protein gH was sufficient to rescue NEDA in the context of infection with a virus that otherwise does not support strong late viral protein expression. We argue that NEDA is a cellular stress response triggered late during HSV-1 infection and might compensate for the viral alteration of the macroautophagic response.
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Abstract
Viruses have adapted a broad range of unique mechanisms to modulate the cellular translational machinery to ensure viral translation at the expense of cellular protein synthesis. Many of these promote virus-specific translation by use of molecular tags on viral mRNA such as internal ribosome entry sites (IRES) and genome-linked viral proteins (VPg) that bind translation machinery components in unusual ways and promote RNA circularization. This review describes recent advances in understanding some of the mechanisms in which animal virus mRNAs gain an advantage over cellular transcripts, including new structural and biochemical insights into IRES function and novel proteins that function as alternate met-tRNAimet carriers in translation initiation. Comparisons between animal and plant virus mechanisms that promote translation of viral mRNAs are discussed.
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Affiliation(s)
- Lucas C Reineke
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
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Abstract
Herpes simplex virus, varicella zoster virus, and pseudorabies virus are neurotropic pathogens of the Alphaherpesvirinae subfamily of the Herpesviridae. These viruses efficiently invade the peripheral nervous system and establish lifelong latency in neurons resident in peripheral ganglia. Primary and recurrent infections cycle virus particles between neurons and the peripheral tissues they innervate. This remarkable cycle of infection is the topic of this review. In addition, some of the distinguishing hallmarks of the infections caused by these viruses are evaluated in terms of their underlying similarities.
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Affiliation(s)
- Gregory Smith
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
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Inhibition of TANK binding kinase 1 by herpes simplex virus 1 facilitates productive infection. J Virol 2011; 86:2188-96. [PMID: 22171259 DOI: 10.1128/jvi.05376-11] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The γ(1)34.5 protein of herpes simplex viruses (HSV) is essential for viral pathogenesis, where it precludes translational arrest mediated by double-stranded-RNA-dependent protein kinase (PKR). Paradoxically, inhibition of PKR alone is not sufficient for HSV to exhibit viral virulence. Here we report that γ(1)34.5 inhibits TANK binding kinase 1 (TBK1) through its amino-terminal sequences, which facilitates viral replication and neuroinvasion. Compared to wild-type virus, the γ(1)34.5 mutant lacking the amino terminus induces stronger antiviral immunity. This parallels a defect of γ(1)34.5 for interacting with TBK1 and reducing phosphorylation of interferon (IFN) regulatory factor 3. This activity is independent of PKR. Although resistant to IFN treatment, the γ(1)34.5 amino-terminal deletion mutant replicates at an intermediate level between replication of wild-type virus and that of the γ(1)34.5 null mutant in TBK1(+/+) cells. However, such impaired viral growth is not observed in TBK1(-/-) cells, indicating that the interaction of γ(1)34.5 with TBK1 dictates HSV infection. Upon corneal infection, this mutant replicates transiently but barely invades the trigeminal ganglia or brain, which is a difference from wild-type virus and the γ(1)34.5 null mutant. Therefore, in addition to PKR, γ(1)34.5 negatively regulates TBK1, which contributes viral replication and spread in vivo.
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