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Wang S, Xiang Z, Gao P, Zhang Y, Zhou L, Ge X, Guo X, Han J, Yang H. African swine fever virus structural protein p17 inhibits IRF3 activation by recruiting host protein PR65A and inducing apoptotic degradation of STING. Front Microbiol 2024; 15:1428233. [PMID: 38957619 PMCID: PMC11217484 DOI: 10.3389/fmicb.2024.1428233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Accepted: 06/03/2024] [Indexed: 07/04/2024] Open
Abstract
African swine fever virus (ASFV) is notoriously known for evolving strategies to modulate IFN signaling. Despite lots of efforts, the underlying mechanisms have remained incompletely understood. This study concerns the regulatory role of viral inner membrane protein p17. We found that the ASFV p17 shows a preferential interaction with cGAS-STING-IRF3 pathway, but not the RIG-I-MAVS-NF-κB signaling, and can inhibit both poly(I:C)- and poly(A:T)-induced activation of IRF3, leading to attenuation of IFN-β induction. Mechanistically, p17 interacts with STING and IRF3 and recruits host scaffold protein PR65A, a subunit of cellular phosphatase PP2A, to down-regulate the level of p-IRF3. Also, p17 targets STING for partial degradation via induction of cellular apoptosis that consequently inhibits activation of both p-TBK1 and p-IRF3. Thus, our findings reveal novel regulatory mechanisms for p17 modulation of IFN signaling and shed light on the intricate interplay between ASFV proteins and host immunity.
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Affiliation(s)
- Shimin Wang
- State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
- College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, China
| | - Zhiyong Xiang
- State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Peng Gao
- State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yongning Zhang
- State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Lei Zhou
- State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xinna Ge
- State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xin Guo
- State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jun Han
- State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Hanchun Yang
- State Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
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Broussard G, Ni G, Zhang Z, Li Q, Cano P, Dittmer DP, Damania B. Barrier-to-autointegration factor 1 promotes gammaherpesvirus reactivation from latency. Nat Commun 2023; 14:434. [PMID: 36746947 PMCID: PMC9902469 DOI: 10.1038/s41467-023-35898-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 01/06/2023] [Indexed: 02/08/2023] Open
Abstract
Gammaherpesviruses, including Kaposi sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are DNA viruses that are globally associated with human cancers and establish lifelong latency in the human population. Detection of gammaherpesviral infection by the cGAS-STING innate immune DNA-sensing pathway is critical for suppressing viral reactivation from latency, a process that promotes viral pathogenesis and transmission. We report that barrier-to-autointegration factor 1 (BAF)-mediated suppression of the cGAS-STING signaling pathway is necessary for reactivation of KSHV and EBV. We demonstrate a role for BAF in destabilizing cGAS expression and show that inhibiting BAF expression in latently infected, reactivating, or uninfected cells leads to increased type I interferon-mediated antiviral responses and decreased viral replication. Furthermore, BAF overexpression resulted in decreased cGAS expression at the protein level. These results establish BAF as a key regulator of the lifecycle of gammaherpesviruses and a potential target for treating viral infections and malignancies.
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Affiliation(s)
- Grant Broussard
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Guoxin Ni
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Zhigang Zhang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Qian Li
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Patricio Cano
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Dirk P Dittmer
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Blossom Damania
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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3
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Tabtieng T, Lent RC, Kaku M, Monago Sanchez A, Gaglia MM. Caspase-Mediated Regulation and Cellular Heterogeneity of the cGAS/STING Pathway in Kaposi's Sarcoma-Associated Herpesvirus Infection. mBio 2022; 13:e0244622. [PMID: 36255240 PMCID: PMC9765453 DOI: 10.1128/mbio.02446-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/19/2022] [Indexed: 11/20/2022] Open
Abstract
As a result of the ongoing virus-host arms race, viruses have evolved numerous immune subversion strategies, many of which are aimed at suppressing the production of type I interferons (IFNs). Apoptotic caspases have recently emerged as important regulators of type I IFN signaling both in noninfectious contexts and during viral infection. Despite being widely considered antiviral factors since they can trigger cell death, several apoptotic caspases promote viral replication by suppressing innate immune response. Indeed, we previously discovered that the AIDS-associated oncogenic gammaherpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV) exploits caspase activity to suppress the antiviral type I IFN response and promote viral replication. However, the mechanism of this novel viral immune evasion strategy is poorly understood, particularly with regard to how caspases antagonize IFN signaling during KSHV infection. Here, we show that caspase activity inhibits the DNA sensor cGAS during KSHV lytic replication to block type I IFN induction. Furthermore, we used single-cell RNA sequencing to reveal that the potent antiviral state conferred by caspase inhibition is mediated by an exceptionally small percentage of IFN-β-producing cells, thus uncovering further complexity of IFN regulation during viral infection. Collectively, these results provide insight into multiple levels of cellular type I IFN regulation that viruses co-opt for immune evasion. Unraveling these mechanisms can inform targeted therapeutic strategies for viral infections and reveal cellular mechanisms of regulating interferon signaling in the context of cancer and chronic inflammatory diseases. IMPORTANCE Type I interferons are key factors that dictate the outcome of infectious and inflammatory diseases. Thus, intricate cellular regulatory mechanisms are in place to control IFN responses. While viruses encode their own immune-regulatory proteins, they can also usurp existing cellular interferon regulatory functions. We found that caspase activity during lytic infection with the AIDS-associated oncogenic gammaherpesvirus Kaposi's sarcoma-associated herpesvirus inhibits the DNA sensor cGAS to block the antiviral type I IFN response. Moreover, single-cell RNA sequencing analyses unexpectedly revealed that an exceptionally small subset of infected cells (<5%) produce IFN, yet this is sufficient to confer a potent antiviral state. These findings reveal new aspects of type I IFN regulation and highlight caspases as a druggable target to modulate cGAS activity.
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Affiliation(s)
- Tate Tabtieng
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Program in Biochemistry, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
| | - Rachel C. Lent
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Program in Molecular Microbiology, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
| | - Machika Kaku
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Program in Immunology, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
| | - Alvaro Monago Sanchez
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Faculty of Experimental Sciences, Universidad Francisco de Vitoria, Madrid, Spain
| | - Marta Maria Gaglia
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Program in Biochemistry, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
- Program in Molecular Microbiology, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
- Program in Immunology, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
- Institute for Molecular Virology and Department of Medical Microbiology and Immunology, University of Wisconsin—Madison, Wisconsin, USA
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White MC, Wu X, Damania B. Oncogenic viruses, cancer biology, and innate immunity. Curr Opin Immunol 2022; 78:102253. [PMID: 36240666 DOI: 10.1016/j.coi.2022.102253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Accepted: 09/05/2022] [Indexed: 01/29/2023]
Abstract
Malignancies that arise as a result of viral infection account for roughly 15% of cancer cases worldwide. The innate immune system is the body's first line of defense against oncogenic viral infection and is also involved in the response against viral-driven tumors. In this review, we discuss research advances made over the last five years elucidating how the innate immune system recognizes and responds to oncogenic viruses, how these viruses have evolved to escape this immune pressure, and ways that innate immunity can inform the development of novel therapeutics against oncogenic viral infection and their associated cancers.
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Affiliation(s)
- Maria C White
- Lineberger Comprehensive Cancer Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Microbiology and Immunology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Xinjun Wu
- Lineberger Comprehensive Cancer Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Microbiology and Immunology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Blossom Damania
- Lineberger Comprehensive Cancer Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Microbiology and Immunology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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5
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Moody CA. Regulation of the Innate Immune Response during the Human Papillomavirus Life Cycle. Viruses 2022; 14:v14081797. [PMID: 36016419 PMCID: PMC9412305 DOI: 10.3390/v14081797] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 08/11/2022] [Accepted: 08/15/2022] [Indexed: 12/12/2022] Open
Abstract
High-risk human papillomaviruses (HR HPVs) are associated with multiple human cancers and comprise 5% of the human cancer burden. Although most infections are transient, persistent infections are a major risk factor for cancer development. The life cycle of HPV is intimately linked to epithelial differentiation. HPVs establish infection at a low copy number in the proliferating basal keratinocytes of the stratified epithelium. In contrast, the productive phase of the viral life cycle is activated upon epithelial differentiation, resulting in viral genome amplification, high levels of late gene expression, and the assembly of virions that are shed from the epithelial surface. Avoiding activation of an innate immune response during the course of infection plays a key role in promoting viral persistence as well as completion of the viral life cycle in differentiating epithelial cells. This review highlights the recent advances in our understanding of how HPVs manipulate the host cell environment, often in a type-specific manner, to suppress activation of an innate immune response to establish conditions supportive of viral replication.
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Affiliation(s)
- Cary A. Moody
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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6
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Apoptotic caspases suppress an MDA5-driven IFN response during productive replication of human papillomavirus type 31. Proc Natl Acad Sci U S A 2022; 119:e2200206119. [PMID: 35858339 PMCID: PMC9303994 DOI: 10.1073/pnas.2200206119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Human papillomaviruses (HPVs) infect the basal proliferating cells of the stratified epithelium, but the productive phase of the life cycle (consisting of viral genome amplification, late gene expression, and virion assembly) is restricted to the highly differentiated suprabasal cells. While much is known regarding the mechanisms that HPVs use to block activation of an innate immune response in undifferentiated cells, little is known concerning how HPV prevents an interferon (IFN) response upon differentiation. Here, we demonstrate that high-risk HPVs hijack a natural function of apoptotic caspases to suppress an IFN response in differentiating epithelial cells. We show that caspase inhibition results in the secretion of type I and type III IFNs that can act in a paracrine manner to induce expression of interferon-stimulated genes (ISGs) and block productive replication of HPV31. Importantly, we demonstrate that the expression of IFNs is triggered by the melanoma differentiation-associated gene 5 (MDA5)-mitochondrial antiviral-signaling protein (MAVS)-TBK1 (TANK-binding kinase 1) pathway, signifying a response to double-stranded RNA (dsRNA). Additionally, we identify a role for MDA5 and MAVS in restricting productive viral replication during the normal HPV life cycle. This study identifies a mechanism by which HPV reprograms the cellular environment of differentiating cells through caspase activation, co-opting a nondeath function of proteins normally involved in apoptosis to block antiviral signaling and promote viral replication.
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7
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Caspase-Mediated Cleavage of the Transcription Factor Sp3: Possible Relevance to Cancer and the Lytic Cycle of Kaposi's Sarcoma-Associated Herpesvirus. Microbiol Spectr 2022; 10:e0146421. [PMID: 35019687 PMCID: PMC8754129 DOI: 10.1128/spectrum.01464-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The open reading frame 50 (ORF50) protein of Kaposi's sarcoma-associated herpesvirus (KSHV) is the master regulator essential for initiating the viral lytic cycle. Previously, we have demonstrated that the ORF50 protein can cooperate with Sp3 to synergistically activate a set of viral and cellular gene promoters through highly conserved ORF50-responsive elements that harbor a Sp3-binding motif. Herein, we show that Sp3 undergoes proteolytic cleavage during the viral lytic cycle, and the cleavage of Sp3 is dependent on caspase activation. Since similar cleavage patterns of Sp3 could be detected in both KSHV-positive and KSHV-negative lymphoma cells undergoing apoptosis, the proteolytic cleavage of Sp3 could be a common event during apoptosis. Mutational analysis identifies 12 caspase cleavage sites in Sp3, which are situated at the aspartate (D) positions D17, D19, D180, D273, D275, D293, D304 (or D307), D326, D344, D530, D543, and D565. Importantly, we noticed that three stable Sp3 C-terminal fragments generated through cleavage at D530, D543, or D565 encompass an intact DNA-binding domain. Like the full-length Sp3, the C-terminal fragments of Sp3 could still retain the ability to cooperate with ORF50 protein to activate specific viral and cellular gene promoters synergistically. Collectively, our findings suggest that despite the proteolytic cleavage of Sp3 under apoptotic conditions, the resultant Sp3 fragments may retain biological activities important for the viral lytic cycle or for cellular apoptosis. IMPORTANCE The ORF50 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) is the key viral protein that controls the switch from latency to lytic reactivation. It is a potent transactivator that can activate target gene promoters via interacting with other cellular DNA-binding transcription factors, such as Sp3. In this report, we show that Sp3 is proteolytically cleaved during the viral lytic cycle, and up to 12 caspase cleavage sites are identified in Sp3. Despite the proteolytic cleavage of Sp3, several resulting C-terminal fragments that have intact zinc-finger DNA-binding domains still retain substantial influence in the synergy with ORF50 to activate specific gene promoters. Overall, our studies elucidate the caspase-mediated cleavage of Sp3 and uncover how ORF50 utilizes the cleavage fragments of Sp3 to transactivate specific viral and cellular gene promoters.
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Sandhu PK, Damania B. The regulation of KSHV lytic reactivation by viral and cellular factors. Curr Opin Virol 2022; 52:39-47. [PMID: 34872030 PMCID: PMC8844089 DOI: 10.1016/j.coviro.2021.11.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 11/03/2021] [Indexed: 02/03/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic herpesvirus that exhibits two distinct phases of infection in the host-latent and lytic. The quiescent latent phase is defined by limited expression of a subset of viral proteins and microRNAs, and an absence of virus production. KSHV periodically reactivates from latency to undergo active lytic replication, leading to production of new infectious virions. This switch from the latent to the lytic phase requires the viral protein regulator of transcription activator (RTA). RTA, along with other virally encoded proteins, is aided by host factors to facilitate this transition. Herein, we highlight the key host proteins that are involved in mediating RTA activation and KSHV lytic replication and discuss the cellular processes in which they function. We will also focus on the modulation of viral reactivation by the innate immune system, and how KSHV influences key immune signaling pathways to aid its own lifecycle.
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Affiliation(s)
- Praneet Kaur Sandhu
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Blossom Damania
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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9
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Herod A, Emond-Rheault JG, Tamber S, Goodridge L, Lévesque RC, Rohde J. Genomic and phenotypic analysis of SspH1 identifies a new Salmonella effector, SspH3. Mol Microbiol 2021; 117:770-789. [PMID: 34942035 DOI: 10.1111/mmi.14871] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 12/19/2021] [Accepted: 12/19/2021] [Indexed: 11/28/2022]
Abstract
Salmonella is a major foodborne pathogen and is responsible for a range of diseases. Not all Salmonella contribute to severe health outcomes as there is a large degree of genetic heterogeneity among the 2600 serovars within the genus. This variability across Salmonella serovars is linked to numerous genetic elements that dictate virulence. While several genetic elements encode virulence factors with well documented contributions to pathogenesis, many genetic elements implicated in Salmonella virulence remain uncharacterized. Many pathogens encode a family of E3 ubiquitin ligases that are delivered into the cells that they infect using a Type 3 Secretion System (T3SS). These effectors, known as NEL-domain E3s, were first characterized in Salmonella. Most Salmonella encode the NEL-effectors sspH2 and slrP, whereas only a subset of Salmonella encode sspH1. SspH1 has been shown to ubiquitinate the mammalian protein kinase PKN1, which has been reported to negatively regulate the pro-survival program Akt. We discovered that SspH1 mediates the degradation of PKN1 during infection of a macrophage cell line but that this degradation does not impact Akt signaling. Genomic analysis of a large collection of Salmonella genomes identified a putative new gene, sspH3, with homology to sspH1. SspH3 is a novel NEL-domain effector.
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Affiliation(s)
- Adrian Herod
- Department of Microbiology and Immunology, Dalhousie University Halifax, Halifax, NS, B3H 4R2, Canada
| | | | - Sandeep Tamber
- Microbiology Research Division, Bureau of Microbial Hazards, Health Canada, Ottawa, ON, Canada
| | - Lawrence Goodridge
- Food Science Department, University of Guelph, East Guelph, ON, N1G 2W1, Canada
| | - Roger C Lévesque
- Institute for Integrative and Systems Biology, Université Laval, Québec City, QC, G1V 0A6, Canada
| | - John Rohde
- Department of Microbiology and Immunology, Dalhousie University Halifax, Halifax, NS, B3H 4R2, Canada
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Caspases Switch off the m 6A RNA Modification Pathway to Foster the Replication of a Ubiquitous Human Tumor Virus. mBio 2021; 12:e0170621. [PMID: 34425696 PMCID: PMC8406275 DOI: 10.1128/mbio.01706-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The methylation of RNA at the N6 position of adenosine (m6A) orchestrates multiple biological processes to control development, differentiation, and cell cycle, as well as various aspects of the virus life cycle. How the m6A RNA modification pathway is regulated to finely tune these processes remains poorly understood. Here, we discovered the m6A reader YTHDF2 as a caspase substrate via proteome-wide prediction, followed by in vitro and in vivo validations. We further demonstrated that cleavage-resistant YTHDF2 blocks, while cleavage-mimicking YTHDF2 fragments promote, the replication of a common human oncogenic virus, Epstein-Barr virus (EBV). Intriguingly, our study revealed a feedback regulation between YTHDF2 and caspase-8 via m6A modification of CASP8 mRNA and YTHDF2 cleavage during EBV replication. Further, we discovered that caspases cleave multiple components within the m6A RNA modification pathway to benefit EBV replication. Our study establishes that caspase disarming of the m6A RNA modification machinery fosters EBV replication. IMPORTANCE The discovery of an N6-methyladenosine (m6A) RNA modification pathway has fundamentally altered our understanding of the central dogma of molecular biology. This pathway is controlled by methyltransferases (writers), demethylases (erasers), and specific m6A binding proteins (readers). Emerging studies have linked the m6A RNA modification pathway to the life cycle of various viruses. However, very little is known regarding how this pathway is subverted to benefit viral replication. In this study, we established an unexpected linkage between cellular caspases and the m6A modification pathway, which is critical to drive the reactivation of a common tumor virus, Epstein-Barr virus (EBV).
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Stutz MD, Allison CC, Ojaimi S, Preston SP, Doerflinger M, Arandjelovic P, Whitehead L, Bader SM, Batey D, Asselin-Labat ML, Herold MJ, Strasser A, West NP, Pellegrini M. Macrophage and neutrophil death programs differentially confer resistance to tuberculosis. Immunity 2021; 54:1758-1771.e7. [DOI: 10.1016/j.immuni.2021.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 12/22/2020] [Accepted: 06/14/2021] [Indexed: 12/15/2022]
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12
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Duncan-Lewis C, Hartenian E, King V, Glaunsinger BA. Cytoplasmic mRNA decay represses RNA polymerase II transcription during early apoptosis. eLife 2021; 10:e58342. [PMID: 34085923 PMCID: PMC8192121 DOI: 10.7554/elife.58342] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/03/2021] [Indexed: 12/22/2022] Open
Abstract
RNA abundance is generally sensitive to perturbations in decay and synthesis rates, but crosstalk between RNA polymerase II transcription and cytoplasmic mRNA degradation often leads to compensatory changes in gene expression. Here, we reveal that widespread mRNA decay during early apoptosis represses RNAPII transcription, indicative of positive (rather than compensatory) feedback. This repression requires active cytoplasmic mRNA degradation, which leads to impaired recruitment of components of the transcription preinitiation complex to promoter DNA. Importin α/β-mediated nuclear import is critical for this feedback signaling, suggesting that proteins translocating between the cytoplasm and nucleus connect mRNA decay to transcription. We also show that an analogous pathway activated by viral nucleases similarly depends on nuclear protein import. Collectively, these data demonstrate that accelerated mRNA decay leads to the repression of mRNA transcription, thereby amplifying the shutdown of gene expression. This highlights a conserved gene regulatory mechanism by which cells respond to threats.
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Affiliation(s)
- Christopher Duncan-Lewis
- Department of Molecular and Cell Biology; University of California, BerkeleyBerkeleyUnited States
| | - Ella Hartenian
- Department of Molecular and Cell Biology; University of California, BerkeleyBerkeleyUnited States
| | - Valeria King
- Department of Molecular and Cell Biology; University of California, BerkeleyBerkeleyUnited States
| | - Britt A Glaunsinger
- Department of Molecular and Cell Biology; University of California, BerkeleyBerkeleyUnited States
- Department of Plant and Microbial Biology; University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, BerkeleyBerkeleyUnited States
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13
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Song Y, Dong Y, Liao Y, Liang Z, Yao J, Zhou X. Apoptotic caspases suppress Mycobacterium bovis-induced IFN-β production in murine macrophage. J Infect 2021; 83:61-68. [PMID: 33892015 DOI: 10.1016/j.jinf.2021.04.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 03/16/2021] [Accepted: 04/11/2021] [Indexed: 11/27/2022]
Abstract
Caspases are classified as inflammatory or apoptotic category. Inflammatory caspases participate in inflammasome activation, while apoptotic caspases mediate apoptotic activation. Previous studies have shown that apoptotic caspases prevent the production of IFN-β during apoptosis or virus infection. However, the relationship between apoptotic caspases and IFN-β production during intracellular bacterial infection is still unclear. Here, we investigated the role of apoptotic caspases in IFN-β production induced by Mycobacterium bovis (M. bovis) infection. M. bovis is an intracellular bacterium and belongs to the Mycobacterium tuberculosis complex. M. bovis infection can cause tuberculosis in animals and human beings. In the current study, we found that M. bovis infection triggered mitochondrial stress, which caused the leakage of cytochrome c into the cytoplasm, and in turn, activated the downstream caspase-9 and-3. Furthermore, our results showed that activation of apoptotic caspases reduced IFN-β production during M. bovis infection and vice versa. Confocal microscopy analysis revealed that apoptotic caspases prevented IFN-β production by decreasing p-IRF3 nuclear translocation. Our findings demonstrate that apoptotic caspases negatively regulate the production of IFN-β induced by an intracellular bacterial infection.
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Affiliation(s)
- Yinjuan Song
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Yuhui Dong
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Yi Liao
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China; College of Animal & Veterinary Science, Southwest Minzu University, Chengdu, Sichuan 610041, China
| | - Zhengmin Liang
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Jiao Yao
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Xiangmei Zhou
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
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14
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Cells of the Innate and Adaptive Immune Systems in Kaposi's Sarcoma. J Immunol Res 2020; 2020:8852221. [PMID: 33294468 PMCID: PMC7700054 DOI: 10.1155/2020/8852221] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/29/2020] [Accepted: 11/06/2020] [Indexed: 01/16/2023] Open
Abstract
Kaposi's sarcoma (KS) is an angioproliferative malignancy whose associated etiologic agent is the Kaposi's sarcoma-associated herpesvirus (KSHV). KS is the most prevalent malignancy among HIV-infected individuals globally and is considered an AIDS-defining malignancy. The different forms of KS including HIV-associated KS, iatrogenic (immunosuppression-related) KS, and classical KS in elderly males suggest that immune cell dysregulation is among the key components in promoting KS development in KSHV-infected individuals. It is therefore expected that different cell types of the immune system likely play distinct roles in promoting or inhibiting KS development. This narrative review is focused on discussing cells of the innate and adaptive immune systems in KSHV infection and KS pathogenesis, including how these cells can be useful in the control of KSHV infection and treatment of KS.
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15
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Rodríguez Stewart RM, Raghuram V, Berry JTL, Joshi GN, Mainou BA. Noncanonical Cell Death Induction by Reassortant Reovirus. J Virol 2020; 94:e01613-20. [PMID: 32847857 PMCID: PMC7592226 DOI: 10.1128/jvi.01613-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 08/15/2020] [Indexed: 12/12/2022] Open
Abstract
Triple-negative breast cancer (TNBC) constitutes 10 to 15% of all breast cancer and is associated with worse prognosis than other subtypes of breast cancer. Current therapies are limited to cytotoxic chemotherapy, radiation, and surgery, leaving a need for targeted therapeutics to improve outcomes for TNBC patients. Mammalian orthoreovirus (reovirus) is a nonenveloped, segmented, double-stranded RNA virus in the Reoviridae family. Reovirus preferentially kills transformed cells and is in clinical trials to assess its efficacy against several types of cancer. We previously engineered a reassortant reovirus, r2Reovirus, that infects TNBC cells more efficiently and induces cell death with faster kinetics than parental reoviruses. In this study, we sought to understand the mechanisms by which r2Reovirus induces cell death in TNBC cells. We show that r2Reovirus infection of TNBC cells of a mesenchymal stem-like (MSL) lineage downregulates the mitogen-activated protein kinase/extracellular signal-related kinase pathway and induces nonconventional cell death that is caspase-dependent but caspase 3-independent. Infection of different MSL lineage TNBC cells with r2Reovirus results in caspase 3-dependent cell death. We map the enhanced oncolytic properties of r2Reovirus in TNBC to epistatic interactions between the type 3 Dearing M2 gene segment and type 1 Lang genes. These findings suggest that the genetic composition of the host cell impacts the mechanism of reovirus-induced cell death in TNBC. Together, our data show that understanding host and virus determinants of cell death can identify novel properties and interactions between host and viral gene products that can be exploited for the development of improved viral oncolytics.IMPORTANCE TNBC is unresponsive to hormone therapies, leaving patients afflicted with this disease with limited treatment options. We previously engineered an oncolytic reovirus (r2Reovirus) with enhanced infective and cytotoxic properties in TNBC cells. However, how r2Reovirus promotes TNBC cell death is not known. In this study, we show that reassortant r2Reovirus can promote nonconventional caspase-dependent but caspase 3-independent cell death and that the mechanism of cell death depends on the genetic composition of the host cell. We also map the enhanced oncolytic properties of r2Reovirus in TNBC to interactions between a type 3 M2 gene segment and type 1 genes. Our data show that understanding the interplay between the host cell environment and the genetic composition of oncolytic viruses is crucial for the development of efficacious viral oncolytics.
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Affiliation(s)
- Roxana M Rodríguez Stewart
- Emory University, Atlanta, Georgia, USA
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Jameson T L Berry
- Emory University, Atlanta, Georgia, USA
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Bernardo A Mainou
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia, USA
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16
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The mechanism of how CD95/Fas activates the Type I IFN/STAT1 axis, driving cancer stemness in breast cancer. Sci Rep 2020; 10:1310. [PMID: 31992798 PMCID: PMC6987111 DOI: 10.1038/s41598-020-58211-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 01/09/2020] [Indexed: 01/18/2023] Open
Abstract
CD95/Fas is an apoptosis inducing death receptor. However, it also has multiple nonapoptotic activities that are tumorigenic. Chronic stimulation of CD95 on breast cancer cells can increase their cancer initiating capacity through activation of a type I interferon (IFN-I)/STAT1 pathway when caspases are inhibited. We now show that this activity relies on the canonical components of the CD95 death-inducing signaling complex, FADD and caspase-8, and on the activation of NF-κB. We identified caspase-2 as the antagonistic caspase that downregulates IFN-I production. Once produced, IFN-Is bind to their receptors activating both STAT1 and STAT2 resulting in upregulation of the double stranded (ds)RNA sensor proteins RIG-I and MDA5, and a release of a subset of endogenous retroviruses. Thus, CD95 is part of a complex cell autonomous regulatory network that involves activation of innate immune components that drive cancer stemness and contribute to therapy resistance.
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17
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Epstein-Barr Virus and Innate Immunity: Friends or Foes? Microorganisms 2019; 7:microorganisms7060183. [PMID: 31238570 PMCID: PMC6617214 DOI: 10.3390/microorganisms7060183] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 06/20/2019] [Accepted: 06/22/2019] [Indexed: 12/16/2022] Open
Abstract
Epstein–Barr virus (EBV) successfully persists in the vast majority of adults but causes lymphoid and epithelial malignancies in a small fraction of latently infected individuals. Innate immunity is the first-line antiviral defense, which EBV has to evade in favor of its own replication and infection. EBV uses multiple strategies to perturb innate immune signaling pathways activated by Toll-like, RIG-I-like, NOD-like, and AIM2-like receptors as well as cyclic GMP-AMP synthase. EBV also counteracts interferon production and signaling, including TBK1-IRF3 and JAK-STAT pathways. However, activation of innate immunity also triggers pro-inflammatory response and proteolytic cleavage of caspases, both of which exhibit proviral activity under some circumstances. Pathogenic inflammation also contributes to EBV oncogenesis. EBV activates NFκB signaling and induces pro-inflammatory cytokines. Through differential modulation of the proviral and antiviral roles of caspases and other host factors at different stages of infection, EBV usurps cellular programs for death and inflammation to its own benefits. The outcome of EBV infection is governed by a delicate interplay between innate immunity and EBV. A better understanding of this interplay will instruct prevention and intervention of EBV-associated cancers.
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18
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Bentz GL, Lowrey AJ, Horne DC, Nguyen V, Satterfield AR, Ross TD, Harrod AE, Uchakina ON, McKallip RJ. Using glycyrrhizic acid to target sumoylation processes during Epstein-Barr virus latency. PLoS One 2019; 14:e0217578. [PMID: 31125383 PMCID: PMC6534330 DOI: 10.1371/journal.pone.0217578] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 05/14/2019] [Indexed: 12/24/2022] Open
Abstract
Cellular sumoylation processes are proposed targets for anti-viral and anti-cancer therapies. We reported that Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) dysregulates cellular sumoylation processes, contributing to its oncogenic potential in EBV-associated malignancies. Ginkgolic acid and anacardic acid, known inhibitors of sumoylation, inhibit LMP1-induced protein sumoylation; however, both drugs have adverse effects in hosts. Here we test the effects of glycyrrhizic acid, a medicinal botanical extract with anti-inflammatory, anti-carcinogenic, and anti-viral properties, on cellular sumoylation processes. While glycyrrhizic acid is known to inhibit EBV penetration, its affect on cellular sumoylation processes remains to be documented. We hypothesized that glycyrrhizic acid inhibits cellular sumoylation processes and may be a viable treatment for Epstein-Barr virus-associated malignancies. Results showed that glycyrrhizic acid inhibited sumoylation processes (without affecting ubiquitination processes), limited cell growth, and induced apoptosis in multiple cell lines. Similar to ginkgolic acid; glycyrrhizic acid targeted the first step of the sumoylation process and resulted in low levels of spontaneous EBV reactivation. Glycyrrhizic acid did not affect induced reactivation of the virus, but the presence of the extract did reduce the ability of the produced virus to infect additional cells. Therefore, we propose that glycyrrhizic acid may be a potential therapeutic drug to augment the treatment of EBV-associated lymphoid malignancies.
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Affiliation(s)
- Gretchen L Bentz
- Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, United States of America
| | - Angela J Lowrey
- Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, United States of America
| | - Dustin C Horne
- Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, United States of America
| | - Vy Nguyen
- Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, United States of America
| | - Austin R Satterfield
- Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, United States of America
| | - Tabithia D Ross
- Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, United States of America
| | - Abigail E Harrod
- Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, United States of America
| | - Olga N Uchakina
- Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, United States of America
| | - Robert J McKallip
- Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, United States of America
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19
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Emerging Proviral Roles of Caspases during Lytic Replication of Gammaherpesviruses. J Virol 2018; 92:JVI.01011-17. [PMID: 30021896 DOI: 10.1128/jvi.01011-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Due to their roles in the regulation of programmed cell death and inflammation, the cellular caspase proteases are considered antiviral factors. However, recent studies have revealed examples of proviral functions for caspases. Here, we review a growing body of literature on the role of caspases in promoting the replication of human gammaherpesviruses. We propose that gammaherpesviruses have evolved ways to redirect these enzymes and to use their activation to support viral replication and immune evasion.
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