1
|
Yang Z, Nicholas J. Biologically significant interaction of human herpesvirus 8 viral interferon regulatory factor 4 with ubiquitin-specific protease 7. J Virol 2024; 98:e0025524. [PMID: 38752725 DOI: 10.1128/jvi.00255-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 04/19/2024] [Indexed: 06/14/2024] Open
Abstract
Human herpesvirus 8 (HHV-8), associated with Kaposi sarcoma, primary effusion lymphoma (PEL), and multicentric Castleman disease, encodes four interferon regulatory factor homologs, vIRFs 1-4, that interact with and inhibit various mediators of host-cell defense against virus infection. A cellular protein targeted by all the vIRFs is ubiquitin-specific protease 7 (USP7); while replication-modulatory and latently infected PEL-cell pro-viability phenotypes of USP7 targeting have been identified for vIRFs 1-3, the significance of the interaction of vIRF-4 with USP7 has remained undetermined. Here we show, through genetic ablation of the vIRF-4-USP7 interaction in infected cells, that vIRF-4 association with USP7 is necessary for optimal expression of vIRF-4 and normal HHV-8 replication. Findings from experiments on transfected and infected cells identified ubiquitination of vIRF-4 via K48-linkage and USP7-binding-associated suppression of vIRF-4 ubiquitination and, in infected cells, increased vIRF-4 expression. Analysis of IFN-I induction and associated signaling as a function of vIRF-4 and its interaction with USP7 identified a role of each in innate-immune suppression. Finally, activation via K63-polyubiquitination of the innate-immune signaling mediator TRAF3 was found to be suppressed by vIRF-4 in a USP7-binding-associated manner in infected cells, but not in transfected cells, likely via binding-regulated expression of vIRF-4. Together, our data identify the first examples of vIRF ubiquitination and a vIRF substrate of USP7, enhanced expression of vIRF-4 via its interaction with USP7, and TRAF3-inhibitory activity of vIRF-4. The findings address, for the first time, the biological significance of the interaction of vIRF-4 with USP7 and reveal a mechanism of vIRF-4-mediated innate-immune evasion and pro-replication activity via TRAF3 regulation. IMPORTANCE HHV-8 homologs of cellular interferon regulatory factors (IRFs), involved in host-cell defense against virus infection, interact in an inhibitory fashion with IRFs and other mediators of antiviral innate immunity. These interactions are of demonstrated or hypothesized importance for successful primary, productive (lytic), and latent (persistent) infection by HHV-8. While HHV-8 vIRF-4 is known to interact physically with USP7 deubiquitinase, a key regulator of various cellular proteins, the functional and biological significance of the interaction has not been addressed. The present study identifies the interaction as important for HHV-8 productive replication and, indeed, for vIRF-4 expression and reveals a new function of vIRF-4 via inhibition of the activity of TRAF3, a pivotal mediator of host-cell antiviral activity through activation of cellular IRFs and induction of type-I interferons. These findings identify potential targets for the development of novel anti-HHV-8 agents, such as those able to disrupt vIRF-4-USP7 interaction or vIRF-4-stabilizing USP7 activity.
Collapse
Affiliation(s)
- Zunlin Yang
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - John Nicholas
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| |
Collapse
|
2
|
Appiah C, Chen S, Pori AI, Retyunskiy V, Tzeng C, Zhao Y. Study of alloferon, a novel immunomodulatory antimicrobial peptide (AMP), and its analogues. Front Pharmacol 2024; 15:1359261. [PMID: 38434708 PMCID: PMC10904621 DOI: 10.3389/fphar.2024.1359261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/05/2024] [Indexed: 03/05/2024] Open
Abstract
Antimicrobial peptides (AMPs) are widely distributed throughout the biosphere and represent a class of conserved peptide molecules with intrinsic antimicrobial properties. Their broad-spectrum antimicrobial activity and low risk to induce resistance have led to increased interest in AMPs as potential alternatives to traditional antibiotics. Among the AMPs, alloferon has been addressed due to its immunomodulatory properties that augment both innate and adaptive immune responses against various pathogens. Alloferon and its analogues have demonstrated pharmaceutical potential through their ability to enhance Natural Killer (NK) cell cytotoxicity and stimulate interferon (IFN) synthesis in both mouse and human models. Additionally, they have shown promise in augmenting antiviral and antitumor activities in mice. In this article, we provide a comprehensive review of the biological effects of alloferon and its analogues, incorporating our own research findings as well. These insights may contribute to a deeper understanding of the therapeutic potential of these novel AMPs.
Collapse
Affiliation(s)
- Clara Appiah
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, China
| | - Shitian Chen
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, China
| | - Afia Ibnat Pori
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, China
| | | | - Chimeng Tzeng
- School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Ye Zhao
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, China
| |
Collapse
|
3
|
Yang Z, Xiang Q, Nicholas J. Direct and biologically significant interactions of human herpesvirus 8 interferon regulatory factor 1 with STAT3 and Janus kinase TYK2. PLoS Pathog 2023; 19:e1011806. [PMID: 37983265 PMCID: PMC10695398 DOI: 10.1371/journal.ppat.1011806] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 12/04/2023] [Accepted: 11/07/2023] [Indexed: 11/22/2023] Open
Abstract
Human herpesvirus 8 (HHV-8) encodes four viral interferon regulatory factors (vIRFs) that target cellular IRFs and/or other innate-immune and stress signaling regulators and suppress the cellular response to viral infection and replication. For vIRF-1, cellular protein targets include IRFs, p53, p53-activating ATM kinase, BH3-only proteins, and antiviral signaling effectors MAVS and STING; vIRF-1 inhibits each, with demonstrated or likely promotion of HHV-8 de novo infection and productive replication. Here, we identify direct interactions of vIRF-1 with STAT3 and STAT-activating Janus kinase TYK2 (the latter reported previously by us to be inhibited by vIRF-1) and suppression by vIRF-1 of cytokine-induced STAT3 activation. Suppression of active, phosphorylated STAT3 (pSTAT3) by vIRF-1 was evident in transfected cells and vIRF-1 ablation in lytically-reactivated recombinant-HHV-8-infected cells led to increased levels of pSTAT3. Using a panel of vIRF-1 deletion variants, regions of vIRF-1 required for interactions with STAT3 and TYK2 were identified, which enabled correlation of STAT3 signaling inhibition by vIRF-1 with TYK2 binding, independently of STAT3 interaction. A viral mutant expressing vIRF-1 deletion-variant Δ198-222 refractory for TYK2 interaction and pSTAT3 suppression was severely compromised for productive replication. Conversely, expression of phosphatase-resistant, protractedly-active STAT3 led to impaired HHV-8 replication. Cells infected with HHV-8 mutants expressing STAT3-refractory vIRF-1 deletion variants or depleted of STAT3 displayed reduced vIRF-1 expression, while custom-peptide-promoted STAT3 interaction could effect increased vIRF-1 expression and enhanced virus replication. Taken together, our data identify vIRF-1 targeting and inhibition of TYK2 as a mechanism of STAT3-signaling suppression and critical for HHV-8 productive replication, the importance of specific pSTAT3 levels for replication, positive roles of STAT3 and vIRF-1-STAT3 interaction in vIRF-1 expression, and significant contributions to lytic replication of STAT3 targeting by vIRF-1.
Collapse
Affiliation(s)
- Zunlin Yang
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Qiwang Xiang
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - John Nicholas
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| |
Collapse
|
4
|
Xiang Q, Yang Z, Nicholas J. STAT and Janus kinase targeting by human herpesvirus 8 interferon regulatory factor in the suppression of type-I interferon signaling. PLoS Pathog 2022; 18:e1010676. [PMID: 35776779 PMCID: PMC9307175 DOI: 10.1371/journal.ppat.1010676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 07/22/2022] [Accepted: 06/15/2022] [Indexed: 11/18/2022] Open
Abstract
Human herpesvirus 8 (HHV-8), also known as Kaposi’s sarcoma (KS)-associated herpesvirus, is involved etiologically in AIDS-associated KS, primary effusion lymphoma (PEL), and multicentric Castleman’s disease, in which both viral latent and lytic functions are important. HHV-8 encodes four viral interferon regulatory factors (vIRFs) that are believed to contribute to viral latency (in PEL cells, at least) and/or to productive replication via suppression of cellular antiviral and stress signaling. Here, we identify vIRF-1 interactions with signal transducer and activator of transcription (STAT) factors 1 and 2, interferon (IFN)-stimulated gene factor 3 (ISGF3) cofactor IRF9, and associated signal transducing Janus kinases JAK1 and TYK2. In naturally infected PEL cells and in iSLK epithelial cells infected experimentally with genetically engineered HHV-8, vIRF-1 depletion or ablation, respectively, led to increased levels of active (phosphorylated) STAT1 and STAT2 in IFNβ-treated, and untreated, cells during lytic replication and to associated cellular-gene induction. In transfected 293T cells, used for mechanistic studies, suppression by vIRF-1 of IFNβ-induced phospho-STAT1 (pSTAT1) was found to be highly dependent on STAT2, indicating vIRF-1-mediated inhibition and/or dissociation of ISGF3-complexing, resulting in susceptibility of pSTAT1 to inactivating dephosphorylation. Indeed, coprecipitation experiments involving targeted precipitation of ISGF3 components identified suppression of mutual interactions by vIRF-1. In contrast, suppression of IFNβ-induced pSTAT2 was effected by regulation of STAT2 activation, likely via detected inhibition of TYK2 and its interactions with STAT2 and IFN type-I receptor (IFNAR). Our identified vIRF-1 interactions with IFN-signaling mediators STATs 1 and 2, co-interacting ISGF3 component IRF9, and STAT-activating TYK2 and the suppression of IFN signaling via ISGF3, TYK2-STAT2 and TYK2-IFNAR disruption and TYK2 inhibition represent novel mechanisms of vIRF function and HHV-8 evasion from host-cell defenses. Viral interferon regulatory factors (vIRFs) encoded by Kaposi’s sarcoma- and lymphoma-associated human herpesvirus 8 (HHV-8) are mediators of protection from cellular antiviral responses and therefore are considered to be pivotal for successful de novo infection, latency establishment and maintenance, and productive (lytic) replication. Identification and characterization of their interactions with cellular proteins, the functional consequences of these interactions, and the operation of these mechanisms in the context of infection has the potential to enable the development of novel antiviral strategies targeted to these interactions and mechanisms. In this report we identify vIRF-1 interactions with transcription factors STAT1 and STAT2, the co-interacting component, IRF9, of the antiviral interferon (IFN)-induced transcription complex ISGF3, and the ability of vIRF-1 to inhibit activation and functional associations of IFN-I receptor- and STAT1/2-kinase TYK2, suppress STAT1/2 activation, and dissociate STAT1 from IFN-induced ISGF3 to blunt IFN signaling and promote STAT1 inactivation. These interactions and activities, which mediate suppression of innate cellular defenses against virus replication, represent novel properties among vIRFs and could potentially be exploited for antiviral and therapeutic purposes.
Collapse
Affiliation(s)
- Qiwang Xiang
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Zunlin Yang
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - John Nicholas
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
| |
Collapse
|
5
|
Bojagora A, Saridakis V. USP7 manipulation by viral proteins. Virus Res 2020; 286:198076. [DOI: 10.1016/j.virusres.2020.198076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 05/14/2020] [Accepted: 06/24/2020] [Indexed: 01/27/2023]
|
6
|
B Cell-Intrinsic Expression of Interferon Regulatory Factor 1 Supports Chronic Murine Gammaherpesvirus 68 Infection. J Virol 2020; 94:JVI.00399-20. [PMID: 32321819 DOI: 10.1128/jvi.00399-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 04/10/2020] [Indexed: 02/07/2023] Open
Abstract
Gammaherpesviruses are ubiquitous pathogens that are associated with cancers, including B cell lymphomas. These viruses are unique in that they infect naive B cells and subsequently drive a robust polyclonal germinal center response in order to amplify the latent reservoir and to establish lifelong infection in memory B cells. The gammaherpesvirus-driven germinal center response in combination with robust infection of germinal center B cells is thought to precipitate lymphomagenesis. Importantly, host and viral factors that selectively affect the gammaherpesvirus-driven germinal center response remain poorly understood. Global deficiency of antiviral tumor-suppressive interferon regulatory factor 1 (IRF-1) selectively promotes the murine gammaherpesvirus 68 (MHV68)-driven germinal center response and expansion of the viral latent reservoir. To determine the extent to which antiviral effects of IRF-1 are B cell intrinsic, we generated mice with conditional IRF-1 deficiency. Surprisingly, B cell-specific IRF-1 deficiency attenuated the establishment of chronic infection and the germinal center response, indicating that MHV68 may, in a B cell-intrinsic manner, usurp IRF-1 to promote the germinal center response and expansion of the latent reservoir. Further, we found that B cell-specific IRF-1 deficiency led to reduced levels of active tyrosine phosphatase SHP1, which plays a B cell-intrinsic proviral function during MHV68 infection. Finally, results of this study indicate that the antiviral functions of IRF-1 unveiled in MHV68-infected mice with global IRF-1 deficiency are mediated via IRF-1 expression by non-B cell populations.IMPORTANCE Gammaherpesviruses establish lifelong infection in over 95% of all adults and are associated with B cell lymphomas. The virus's manipulation of the germinal center response and B cell differentiation to establish lifelong infection is thought to also precipitate malignant transformation, through a mechanism that remains poorly understood. The host transcription factor IRF-1, a well-established tumor suppressor, selectively attenuates MHV68-driven germinal center response, a phenotype that we originally hypothesized to occur in a B cell-intrinsic manner. In contrast, in testing, B cell-intrinsic IRF-1 expression promoted the MHV68-driven germinal center response and the establishment of chronic infection. Our report highlights the underappreciated multifaceted role of IRF-1 in MHV68 infection and pathogenesis.
Collapse
|
7
|
Fröhlich J, Grundhoff A. Epigenetic control in Kaposi sarcoma-associated herpesvirus infection and associated disease. Semin Immunopathol 2020; 42:143-157. [PMID: 32219477 PMCID: PMC7174275 DOI: 10.1007/s00281-020-00787-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/20/2020] [Indexed: 12/15/2022]
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) is the etiologic agent of several malignancies of endothelial and B-cell origin. The fact that latently infected tumor cells in these malignancies do not express classical viral oncogenes suggests that pathogenesis of KSHV-associated disease results from multistep processes that, in addition to constitutive viral gene expression, may require accumulation of cellular alterations. Heritable changes of the epigenome have emerged as an important co-factor that contributes to the pathogenesis of many non-viral cancers. Since KSHV encodes a number of factors that directly or indirectly manipulate host cell chromatin, it is an intriguing possibility that epigenetic reprogramming also contributes to the pathogenesis of KSHV-associated tumors. The fact that heritable histone modifications have also been shown to regulate viral gene expression programs in KSHV-infected tumor cells underlines the importance of epigenetic control during latency and tumorigenesis. We here review what is presently known about the role of epigenetic regulation of viral and host chromatin in KSHV infection and discuss how viral manipulation of these processes may contribute to the development of KSHV-associated disease.
Collapse
Affiliation(s)
- Jacqueline Fröhlich
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Adam Grundhoff
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany.
| |
Collapse
|
8
|
Xiang Q, Ju H, Nicholas J. USP7-Dependent Regulation of TRAF Activation and Signaling by a Viral Interferon Regulatory Factor Homologue. J Virol 2020; 94:e01553-19. [PMID: 31666375 PMCID: PMC6955280 DOI: 10.1128/jvi.01553-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 10/22/2019] [Indexed: 01/12/2023] Open
Abstract
Human herpesvirus 8 (HHV-8) encodes four viral interferon regulatory factors (vIRFs 1 to 4), all of which are expressed during lytic replication and inhibit a variety of antiviral signaling pathways. Viral IRFs 1, 2, and 3 are also expressed during latency in primary effusion lymphoma (PEL) cells, and vIRF-1 and vIRF-3 have been reported to promote PEL cell viability. Viral IRFs 1, 3, and 4 are known to interact with ubiquitin-specific protease 7 (USP7); interactions of vIRF-1 and vIRF-3 with USP7 promote PEL cell viability and regulate productive replication. Here, we report that vIRF-2 also targets USP7, utilizing a PSTS motif matching the USP7 N-terminal domain-binding A/PxxS consensus, but uniquely requires catalytic domain residues for intracellular interaction. In functional and mechanistic analyses, tumor necrosis factor receptor-associated factor (TRAF)-mediated signaling and associated polyubiquitination of TRAFs 3 and 6, specifically, were regulated negatively by USP7 and positively by vIRF-2-USP7 interaction, the latter competing for USP7-TRAF association. Using depletion, depletion-complementation, and targeted mutagenesis approaches, vIRF-2 was determined to promote latent PEL cell viability, likely independently of USP7 interaction, while lytic replication was inhibited by vIRF-2, in part or in whole via USP7 interaction. Together, our data identify a new molecular determinant of USP7 recognition, TRAF3/6-specific targeting by the deubiquitinase, associated activation of these TRAFs by vIRF-2, and activities of vIRF-2 and vIRF-2-USP7 interaction in HHV-8 latent and lytic biology.IMPORTANCE Human herpesvirus 8-encoded IRF homologues were the first to be identified in a virus. Through inhibitory interactions with cellular IRFs and other mediators of antiviral signaling, the vIRFs are believed to be essential for productive replication and also for latency in particular cell types. The deubiquitinase USP7 is a regulator of key cellular pathways, modulates HHV-8 latent and lytic infection, and is targeted by vIRFs 1, 3, and 4. Here, we report that vIRF-2 also interacts with USP7, via a means distinguishable from USP7 interactions with other vIRFs and other proteins, that this interaction modulates antiviral signaling via disruption of USP7 interactions with innate immune signaling proteins TRAF3 and TRAF6, and that vIRF-2 targeting of USP7 regulates HHV-8 productive replication. The presented data are the first to identify vIRF-2 targeting of USP7 and its role in HHV-8 biology, expanding our understanding of the repertoire and importance of virus-host interactions.
Collapse
Affiliation(s)
- Qiwang Xiang
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hyunwoo Ju
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - John Nicholas
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| |
Collapse
|
9
|
Golas G, Jang SJ, Naik NG, Alonso JD, Papp B, Toth Z. Comparative analysis of the viral interferon regulatory factors of KSHV for their requisite for virus production and inhibition of the type I interferon pathway. Virology 2019; 541:160-173. [PMID: 32056714 DOI: 10.1016/j.virol.2019.12.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 12/19/2019] [Accepted: 12/27/2019] [Indexed: 01/23/2023]
Abstract
Unique among human viruses, Kaposi's sarcoma-associated herpesvirus (KSHV) encodes several homologs of cellular interferon regulatory factors (vIRFs). Since KSHV expresses multiple factors that can inhibit interferon (IFN) signaling to promote virus production, it is still unclear to what extent vIRFs contribute to these specific processes during KSHV infection. To study the function of vIRFs during viral infection, we engineered 3xFLAG-tagged-vIRF and vIRF-knockout recombinant KSHV clones, which were utilized to test vIRF expression, as well as their requirement for viral replication, virus production, and inhibition of the type I IFN pathway in different models of lytic KSHV infection. Our data show that all vIRFs can be expressed as lytic viral proteins, yet were dispensable for KSHV production and inhibition of type I IFN. Nevertheless, as vIRFs were able to suppress IFN-stimulated antiviral genes, vIRFs may still promote the KSHV lytic cycle in the presence of an ongoing antiviral response.
Collapse
Affiliation(s)
- Gavin Golas
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA
| | - Seung Jin Jang
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA
| | - Nenavath Gopal Naik
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA
| | - Juan D Alonso
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA
| | - Bernadett Papp
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA; UF Genetics Institute, Gainesville, FL, 32610, USA; UF Health Cancer Center, Gainesville, FL, 32610, USA; UF Informatics Institute, Gainesville, FL, 32610, USA
| | - Zsolt Toth
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL, 32610, USA; UF Genetics Institute, Gainesville, FL, 32610, USA; UF Health Cancer Center, Gainesville, FL, 32610, USA.
| |
Collapse
|
10
|
Vo MT, Smith BJ, Nicholas J, Choi YB. Activation of NIX-mediated mitophagy by an interferon regulatory factor homologue of human herpesvirus. Nat Commun 2019; 10:3203. [PMID: 31324791 PMCID: PMC6642096 DOI: 10.1038/s41467-019-11164-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 06/24/2019] [Indexed: 01/07/2023] Open
Abstract
Viral control of mitochondrial quality and content has emerged as an important mechanism for counteracting the host response to virus infection. Despite the knowledge of this crucial function of some viruses, little is known about how herpesviruses regulate mitochondrial homeostasis during infection. Human herpesvirus 8 (HHV-8) is an oncogenic virus causally related to AIDS-associated malignancies. Here, we show that HHV-8-encoded viral interferon regulatory factor 1 (vIRF-1) promotes mitochondrial clearance by activating mitophagy to support virus replication. Genetic interference with vIRF-1 expression or targeting to the mitochondria inhibits HHV-8 replication-induced mitophagy and leads to an accumulation of mitochondria. Moreover, vIRF-1 binds directly to a mitophagy receptor, NIX, on the mitochondria and activates NIX-mediated mitophagy to promote mitochondrial clearance. Genetic and pharmacological interruption of vIRF-1/NIX-activated mitophagy inhibits HHV-8 productive replication. Our findings uncover an essential role of vIRF-1 in mitophagy activation and promotion of HHV-8 lytic replication via this mechanism.
Collapse
Affiliation(s)
- Mai Tram Vo
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Barbara J Smith
- Department of Cell Biology, Institute for Basic Biomedical Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - John Nicholas
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Young Bong Choi
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA.
| |
Collapse
|
11
|
Koch S, Damas M, Freise A, Hage E, Dhingra A, Rückert J, Gallo A, Kremmer E, Tegge W, Brönstrup M, Brune W, Schulz TF. Kaposi's sarcoma-associated herpesvirus vIRF2 protein utilizes an IFN-dependent pathway to regulate viral early gene expression. PLoS Pathog 2019; 15:e1007743. [PMID: 31059555 PMCID: PMC6522069 DOI: 10.1371/journal.ppat.1007743] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 05/16/2019] [Accepted: 03/31/2019] [Indexed: 12/14/2022] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) belongs to the subfamily of Gammaherpesvirinae and is the etiological agent of Kaposi’s sarcoma as well as of two lymphoproliferative diseases: primary effusion lymphoma and multicentric Castleman disease. The KSHV life cycle is divided into a latent and a lytic phase and is highly regulated by viral immunomodulatory proteins which control the host antiviral immune response. Among them is a group of proteins with homology to cellular interferon regulatory factors, the viral interferon regulatory factors 1–4. The KSHV vIRFs are known as inhibitors of cellular interferon signaling and are involved in different oncogenic pathways. Here we characterized the role of the second vIRF protein, vIRF2, during the KSHV life cycle. We found the vIRF2 protein to be expressed in different KSHV positive cells with early lytic kinetics. Importantly, we observed that vIRF2 suppresses the expression of viral early lytic genes in both newly infected and reactivated persistently infected endothelial cells. This vIRF2-dependent regulation of the KSHV life cycle might involve the increased expression of cellular interferon-induced genes such as the IFIT proteins 1, 2 and 3, which antagonize the expression of early KSHV lytic proteins. Our findings suggest a model in which the viral protein vIRF2 allows KSHV to harness an IFN-dependent pathway to regulate KSHV early gene expression. The life cycle of Kaposi Sarcoma herpesvirus involves both persistence in a latent form and productive replication to generate new viral particles. How the virus switches between latency and productive (‘lytic’) replication is only partially understood. Here we show that a viral homologue of interferon regulatory factors, vIRF2, antagonizes lytic protein expression in endothelial cells. It does this by inducing the expression of cellular interferon-regulated genes such as IFIT 1–3, which in turn dampens early viral gene expression. This observation suggests that vIRF2 allows KSHV to harness the interferon pathway to regulate early viral gene expression in endothelial cells.
Collapse
Affiliation(s)
- Sandra Koch
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Modester Damas
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Anika Freise
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Elias Hage
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Akshay Dhingra
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Jessica Rückert
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Antonio Gallo
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
- German Centre for Infection Research, Hamburg Site, Germany
| | - Elisabeth Kremmer
- Institute of Molecular Immunology, Helmholtz Centre Munich, German Research Center for Environmental Health, Munich, Germany
| | - Werner Tegge
- Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Mark Brönstrup
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
- Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Wolfram Brune
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
- German Centre for Infection Research, Hamburg Site, Germany
| | - Thomas F. Schulz
- Hannover Medical School, Institute of Virology, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
- * E-mail:
| |
Collapse
|
12
|
|