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Zhang X, Zheng R, Li Z, Ma J. Liquid-liquid Phase Separation in Viral Function. J Mol Biol 2023; 435:167955. [PMID: 36642156 DOI: 10.1016/j.jmb.2023.167955] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 01/04/2023] [Accepted: 01/07/2023] [Indexed: 01/15/2023]
Abstract
An emerging set of results suggests that liquid-liquid phase separation (LLPS) is the basis for the formation of membrane-less compartments in cells. Evidence is now mounting that various types of virus-induced membrane-less compartments and organelles are also assembled via LLPS. Specifically, viruses appear to use intracellular phase transitions to form subcellular microenvironments known as viral factories, inclusion bodies, or viroplasms. These compartments - collectively referred to as viral biomolecular condensates - can be used to concentrate replicase proteins, viral genomes, and host proteins that are required for virus replication. They can also be used to subvert or avoid the intracellular immune response. This review examines how certain DNA or RNA viruses drive the formation of viral condensates, the possible biological functions of those condensates, and the biophysical and biochemical basis for their assembly.
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Affiliation(s)
- Xiaoyue Zhang
- NHC Key Laboratory of Carcinogenesis, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, China; Cancer Research Institute and School of Basic Medical Science, Central South University, Changsha, China; Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Changsha, China
| | - Run Zheng
- Cancer Research Institute and School of Basic Medical Science, Central South University, Changsha, China; Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Changsha, China
| | - Zhengshuo Li
- Cancer Research Institute and School of Basic Medical Science, Central South University, Changsha, China; Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Changsha, China
| | - Jian Ma
- NHC Key Laboratory of Carcinogenesis, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, China; Cancer Research Institute and School of Basic Medical Science, Central South University, Changsha, China; Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Changsha, China.
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2
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Tian X, Zhou Y, Wang S, Gao M, Xia Y, Li Y, Zhong Y, Xu W, Bai L, Fu B, Zhou Y, Lee HR, Deng H, Lan K, Feng P, Zhang J. Genome-Wide CRISPR-Cas9 Screen Identifies SMCHD1 as a Restriction Factor for Herpesviruses. mBio 2023; 14:e0054923. [PMID: 37010434 PMCID: PMC10128004 DOI: 10.1128/mbio.00549-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 03/10/2023] [Indexed: 04/04/2023] Open
Abstract
Intrinsic immunity is the frontline of host defense against invading pathogens. To combat viral infection, mammalian hosts deploy cell-intrinsic effectors to block viral replication prior to the onset of innate and adaptive immunity. In this study, SMCHD1 is identified as a pivotal cellular factor that restricts Kaposi's sarcoma-associated herpesvirus (KSHV) lytic reactivation through a genome-wide CRISPR-Cas9 knockout screen. Genome-wide chromatin profiling revealed that SMCHD1 associates with the KSHV genome, most prominently the origin of lytic DNA replication (ORI-Lyt). SMCHD1 mutants defective in DNA binding could not bind ORI-Lyt and failed to restrict KSHV lytic replication. Moreover, SMCHD1 functioned as a pan-herpesvirus restriction factor that potently suppressed a wide range of herpesviruses, including alpha, beta, and gamma subfamilies. SMCHD1 deficiency facilitated the replication of a murine herpesvirus in vivo. These findings uncovered SMCHD1 as a restriction factor against herpesviruses, and this could be harnessed for the development of antiviral therapies to limit viral infection. IMPORTANCE Intrinsic immunity represents the frontline of host defense against invading pathogens. However, our understanding of cell-intrinsic antiviral effectors remains limited. In this study, we identified SMCHD1 as a cell-intrinsic restriction factor that controlled KSHV lytic reactivation. Moreover, SMCHD1 restricted the replication of a wide range of herpesviruses by targeting the origins of viral DNA replication (ORIs), and SMCHD1 deficiency facilitated the replication of a murine herpesvirus in vivo. This study helps us to better understand intrinsic antiviral immunity, which may be harnessed to develop new therapeutics for the treatment of herpesvirus infection and the related diseases.
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Affiliation(s)
- Xuezhang Tian
- State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, State Key Laboratory of Virology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
- Department of Pulmonary and Critical Care Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China
| | - Yaru Zhou
- State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, State Key Laboratory of Virology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Shaowei Wang
- State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, State Key Laboratory of Virology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Ming Gao
- State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, State Key Laboratory of Virology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Yanlin Xia
- State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, State Key Laboratory of Virology, Medical Research Institute, Wuhan University, Wuhan, China
| | - Yangyang Li
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
- State Key Laboratory of Virology, School of Life Sciences, Wuhan University, Wuhan, China
| | - Yunhong Zhong
- State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, State Key Laboratory of Virology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Wenhao Xu
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Lei Bai
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
- State Key Laboratory of Virology, School of Life Sciences, Wuhan University, Wuhan, China
| | - Bishi Fu
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Yu Zhou
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
- State Key Laboratory of Virology, School of Life Sciences, Wuhan University, Wuhan, China
| | - Hye-Ra Lee
- Department of Biotechnology and Bioinformatics, College of Science and Technology, Korea University, Sejong, South Korea
- Department of Lab Medicine, College of Medicine, Korea University, Seoul, South Korea
| | - Hongyu Deng
- CAS Key Laboratory of Infection and Immunity, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ke Lan
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
- State Key Laboratory of Virology, School of Life Sciences, Wuhan University, Wuhan, China
| | - Pinghui Feng
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California, USA
| | - Junjie Zhang
- State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, State Key Laboratory of Virology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
- Department of Pulmonary and Critical Care Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China
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3
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Lari A, Glaunsinger BA. Murine Gammaherpesvirus 68 ORF45 Stimulates B2 Retrotransposon and Pre-tRNA Activation in a Manner Dependent on Mitogen-Activated Protein Kinase (MAPK) Signaling. Microbiol Spectr 2023; 11:e0017223. [PMID: 36752632 PMCID: PMC10100704 DOI: 10.1128/spectrum.00172-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 01/21/2023] [Indexed: 02/09/2023] Open
Abstract
RNA polymerase III (RNAPIII) transcribes a variety of noncoding RNAs, including tRNA (tRNA) and the B2 family of short interspersed nuclear elements (SINEs). B2 SINEs are noncoding retrotransposons that possess tRNA-like promoters and are normally silenced in healthy somatic tissue. Infection with the murine gammaherpesvirus MHV68 induces transcription of both SINEs and tRNAs, in part through the activity of the viral protein kinase ORF36. Here, we identify the conserved MHV68 tegument protein ORF45 as an additional activator of these RNAPIII loci. MHV68 ORF45 and ORF36 form a complex, resulting in an additive induction RNAPIII and increased ORF45 expression. ORF45-induced RNAPIII transcription is dependent on its activation of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) signaling pathway, which in turn increases the abundance of the RNAPIII transcription factor Brf1. Other viral and nonviral activators of MAPK/ERK signaling also increase the levels of Brf1 protein, B2 SINE RNA, and tRNA, suggesting that this is a common strategy to increase RNAPIII activity. IMPORTANCE Gammaherpesviral infection alters the gene expression landscape of a host cell, including through the induction of noncoding RNAs transcribed by RNA polymerase III (RNAPIII). Among these are a class of repetitive genes known as retrotransposons, which are normally silenced elements and can copy and spread throughout the genome, and transfer RNAs (tRNAs), which are fundamental components of protein translation machinery. How these loci are activated during infection is not well understood. Here, we identify ORF45 from the model murine gammaherpesvirus MHV68 as a novel activator of RNAPIII transcription. To do so, it engages the MAPK/ERK signaling pathway, which is a central regulator of cellular response to environmental stimuli. Activation of this pathway leads to the upregulation of a key factor required for RNAPIII activity, Brf1. These findings expand our understanding of the regulation and dysregulation of RNAPIII transcription and highlight how viral cooption of key signaling pathways can impact host gene expression.
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Affiliation(s)
- Azra Lari
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
| | - Britt A. Glaunsinger
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
- Howard Hughes Medical Institute, Berkeley, California, USA
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4
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The Interaction between Tegument Proteins ORF33 and ORF45 Plays an Essential Role in Cytoplasmic Virion Maturation of a Gammaherpesvirus. J Virol 2022; 96:e0107322. [PMID: 36300940 PMCID: PMC9683023 DOI: 10.1128/jvi.01073-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A critical step in viral lytic replication is the assembly of progeny viral particles. Herpesviruses are important pathogens.
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5
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Zhou S, Fu Z, Zhang Z, Jia X, Xu G, Sun L, Sun F, Gao P, Xu P, Deng H. Liquid-liquid phase separation mediates the formation of herpesvirus assembly compartments. J Biophys Biochem Cytol 2022; 222:213550. [PMID: 36250941 PMCID: PMC9579985 DOI: 10.1083/jcb.202201088] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 07/19/2022] [Accepted: 09/30/2022] [Indexed: 11/22/2022] Open
Abstract
Virus assembly, which takes place during the late stage of viral replication, is essential for virus propagation. However, the underlying mechanisms remain poorly understood, especially for viruses with complicated structures. Here, we use correlative light and electron microscopy to examine the formation of cytoplasmic virion assembly compartments (cVACs) during infection by a γ-herpesvirus. These cVACs are membraneless organelles with liquid-like properties. Formation of cVACs during virus infection is mediated by ORF52, an abundant tegument protein. ORF52 undergoes liquid-liquid phase separation (LLPS), which is promoted by both DNA and RNA. Disrupting ORF52 phase separation blocks cVACs formation and virion production. These results demonstrate that phase separation of ORF52 is critical for cVACs formation. Our work defines herpesvirus cVACs as membraneless compartments that are generated through a process of LLPS mediated by a tegument protein and adds to the cellular processes that are facilitated by phase separation.
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Affiliation(s)
- Sheng Zhou
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Zhifei Fu
- University of Chinese Academy of Sciences, Beijing, China,Public Technology Service Center, Fujian Medical University, Fujian, China,CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,CAS Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Ziwei Zhang
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Xing Jia
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Guangjun Xu
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Long Sun
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Fei Sun
- CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Pu Gao
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Pingyong Xu
- University of Chinese Academy of Sciences, Beijing, China,CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,CAS Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hongyu Deng
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China,CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,Correspondence to Hongyu Deng:
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6
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The ORF45 Protein of Kaposi's Sarcoma-Associated Herpesvirus and Its Critical Role in the Viral Life Cycle. Viruses 2022; 14:v14092010. [PMID: 36146816 PMCID: PMC9506158 DOI: 10.3390/v14092010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/07/2022] [Accepted: 09/07/2022] [Indexed: 11/17/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) protein ORF45 is a virion-associated tegument protein that is unique to the gammaherpesvirus family. Generation of KSHV ORF45-knockout mutants and their subsequent functional analyses have permitted a better understanding of ORF45 and its context-specific and vital role in the KSHV lytic cycle. ORF45 is a multifaceted protein that promotes infection at both the early and late phases of the viral life cycle. As an immediate-early protein, ORF45 is expressed within hours of KSHV lytic reactivation and plays an essential role in promoting the lytic cycle, using multiple mechanisms, including inhibition of the host interferon response. As a tegument protein, ORF45 is necessary for the proper targeting of the viral capsid for envelopment and release, affecting the late stage of the viral life cycle. A growing list of ORF45 interaction partners have been identified, with one of the most well-characterized being the association of ORF45 with the host extracellular-regulated kinase (ERK) p90 ribosomal s6 kinase (RSK) signaling cascade. In this review, we describe ORF45 expression kinetics, as well as the host and viral interaction partners of ORF45 and the significance of these interactions in KSHV biology. Finally, we discuss the role of ORF45 homologs in gammaherpesvirus infections.
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7
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Yang X, Zhou J, Liu C, Qu Y, Wang W, Xiao MZX, Zhu F, Liu Z, Liang Q. KSHV-encoded ORF45 activates human NLRP1 inflammasome. Nat Immunol 2022; 23:916-926. [PMID: 35618833 DOI: 10.1038/s41590-022-01199-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 03/28/2022] [Indexed: 11/08/2022]
Abstract
At steady state, the NOD-like receptor (NLR)-containing pyrin domain (PYD) (NLRP)1 inflammasome is maintained in an auto-inhibitory complex by dipeptidyl peptidases 8 and 9 (DPP8 and DPP9) and is activated by pathogen-encoded proteases after infection. Here, we showed that the open reading frame (ORF)45 protein of the Kaposi's sarcoma-associated herpesvirus activated the human NLRP1 (hNLRP1) inflammasome in a non-protease-dependent manner, and we additionally showed that the Linker1 region of hNLRP1, situated between the PYD and NACHT domains, was required for the auto-inhibition and non-protease-dependent activation of hNLRP1. At steady state, the interaction between Linker1 and the UPA subdomain silenced the activation of hNLRP1 in auto-inhibitory complexes either containing DPP9 or not in a manner independent of DPP9. ORF45 binding to Linker1 displaced UPA from the Linker1-UPA complex and induced the release of the C-terminal domain of hNLRP1 for inflammasome assembly. The ORF45-dependent activation of the NLRP1 inflammasome was conserved in primates but was not observed for murine NLRP1b inflammasomes.
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Affiliation(s)
- Xing Yang
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jingfan Zhou
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chengrong Liu
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yafei Qu
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Weili Wang
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Maggie Z X Xiao
- Faculty of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Fanxiu Zhu
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Zhenshan Liu
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qiming Liang
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Research Center of Translational Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai, China.
- State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China.
- Institute of Pediatric Infection, Immunity and Intensive Care Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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8
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The ORF45 Protein of Kaposi Sarcoma-Associated Herpesvirus Is an Inhibitor of p53 Signaling during Viral Reactivation. J Virol 2021; 95:e0145921. [PMID: 34523970 DOI: 10.1128/jvi.01459-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) is a carcinogenic double-stranded DNA virus and the etiological agent of Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD). To prevent premature apoptosis and support its replication cycle, KSHV expresses a series of open reading frames (ORFs) that regulate signaling by the p53 tumor suppressor protein. Here, we describe a novel viral inhibitor of p53 encoded by KSHV ORF45 and identify its mechanism of action. ORF45 binds to p53 and prevents its interactions with USP7, a p53 deubiquitinase. This results in decreased p53 accumulation, localization of p53 to the cytoplasm, and diminished transcriptional activity. IMPORTANCE Unlike in other cancers, the tumor suppressor protein p53 is rarely mutated in Kaposi sarcoma (KS). Rather, Kaposi sarcoma-associated herpesvirus (KSHV) inactivates p53 through multiple viral proteins. One possible therapeutic approach to KS is the activation of p53, which would result in apoptosis and tumor regression. In this regard, it is important to understand all the mechanisms used by KSHV to modulate p53 signaling. This work describes a novel inhibitor of p53 signaling and a potential drug target, ORF45, and identifies the mechanisms of its action.
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9
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Gillen J, Zhu F. Disruption of the Interaction between ORF33 and the Conserved Carboxyl-Terminus of ORF45 Abolishes Progeny Virion Production of Kaposi Sarcoma-Associated Herpesvirus. Viruses 2021; 13:1828. [PMID: 34578410 PMCID: PMC8472245 DOI: 10.3390/v13091828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 12/12/2022] Open
Abstract
The Open Reading Frame 45 (ORF45) of Kaposi sarcoma-associated herpesvirus (KSHV) is a gammaherpesvirus-specific, immediate-early, tegument protein required for efficient viral replication and virion production. We have previously shown that ORF45 interacts with the conserved herpesviral protein ORF33 through the highly conserved C-terminal 19 amino acids (C19) of ORF45. Because the deletion of C19 abolished ORF33 accumulation and viral production, we reasoned that this interaction could be critical for viral production and explored as an antiviral target for gammaherpesviruses. In work described in this article, we characterize this interaction in further detail, first by revealing that this interaction is conserved among gammaherpesviruses, then by identifying residues in C19 critical for its interaction with and stabilization of ORF33. More importantly, we show that disruption of the interaction, either by mutating key residues (W403A or W405A) in C19 or by using competing cell penetration peptide TAT-C19, dramatically reduce the yield of KSHV progeny viruses. Our results not only reveal critical roles of this interaction to viral production but also provide a proof of concept for targeting the ORF33-ORF45 interaction as a novel antiviral strategy against KSHV and other gammaherpesviruses.
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Affiliation(s)
- Joseph Gillen
- Functional Cellular Networks Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1892, USA;
| | - Fanxiu Zhu
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370, USA
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10
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Lv Y, Zhou S, Gao S, Deng H. Remodeling of host membranes during herpesvirus assembly and egress. Protein Cell 2018; 10:315-326. [PMID: 30242641 PMCID: PMC6468031 DOI: 10.1007/s13238-018-0577-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 08/21/2018] [Indexed: 02/04/2023] Open
Abstract
Many viruses, enveloped or non-enveloped, remodel host membrane structures for their replication, assembly and escape from host cells. Herpesviruses are important human pathogens and cause many diseases. As large enveloped DNA viruses, herpesviruses undergo several complex steps to complete their life cycles and produce infectious progenies. Firstly, herpesvirus assembly initiates in the nucleus, producing nucleocapsids that are too large to cross through the nuclear pores. Nascent nucleocapsids instead bud at the inner nuclear membrane to form primary enveloped virions in the perinuclear space followed by fusion of the primary envelopes with the outer nuclear membrane, to translocate the nucleocapsids into the cytoplasm. Secondly, nucleocapsids obtain a series of tegument proteins in the cytoplasm and bud into vesicles derived from host organelles to acquire viral envelopes. The vesicles are then transported to and fuse with the plasma membrane to release the mature virions to the extracellular space. Therefore, at least two budding and fusion events take place at cellular membrane structures during herpesviruses assembly and egress, which induce membrane deformations. In this review, we describe and discuss how herpesviruses exploit and remodel host membrane structures to assemble and escape from the host cell.
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Affiliation(s)
- Ying Lv
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Sheng Zhou
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shengyan Gao
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Hongyu Deng
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China. .,CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
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11
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Van Skike ND, Minkah NK, Hogan CH, Wu G, Benziger PT, Oldenburg DG, Kara M, Kim-Holzapfel DM, White DW, Tibbetts SA, French JB, Krug LT. Viral FGARAT ORF75A promotes early events in lytic infection and gammaherpesvirus pathogenesis in mice. PLoS Pathog 2018; 14:e1006843. [PMID: 29390024 PMCID: PMC5811070 DOI: 10.1371/journal.ppat.1006843] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 02/13/2018] [Accepted: 12/27/2017] [Indexed: 12/19/2022] Open
Abstract
Gammaherpesviruses encode proteins with homology to the cellular purine metabolic enzyme formyl-glycinamide-phosphoribosyl-amidotransferase (FGARAT), but the role of these viral FGARATs (vFGARATs) in the pathogenesis of a natural host has not been investigated. We report a novel role for the ORF75A vFGARAT of murine gammaherpesvirus 68 (MHV68) in infectious virion production and colonization of mice. MHV68 mutants with premature stop codons in orf75A exhibited a log reduction in acute replication in the lungs after intranasal infection, which preceded a defect in colonization of multiple host reservoirs including the mediastinal lymph nodes, peripheral blood mononuclear cells, and the spleen. Intraperitoneal infection rescued splenic latency, but not reactivation. The 75A.stop virus also exhibited defective replication in primary fibroblast and macrophage cells. Viruses produced in the absence of ORF75A were characterized by an increase in the ratio of particles to PFU. In the next round of infection this led to the alteration of early events in lytic replication including the deposition of the ORF75C tegument protein, the accelerated kinetics of viral gene expression, and induction of TNFα release and cell death. Infecting cells to deliver equivalent genomes revealed that ORF75A was required for initiating early events in infection. In contrast with the numerous phenotypes observed in the absence of ORF75A, ORF75B was dispensable for replication and pathogenesis. These studies reveal that murine rhadinovirus vFGARAT family members ORF75A and ORF75C have evolved to perform divergent functions that promote replication and colonization of the host. Gammaherpesviruses are infectious agents that cause cancer. The study of viral genes unique to this subfamily may offer insight into the strategies that these viruses use to persist in the host and drive disease. The vFGARATs are a family of viral proteins found only in gammaherpesviruses, and are critical for replication in cell culture. Here we report that a rhadinovirus of rodents requires a previously uncharacterized vFGARAT family member, ORF75A, to support viral growth and persistence in mice. In addition, viruses lacking ORF75A are defective in the production of infectious viral particles. Thus, duplications and functional divergence of the various vFGARATs in the rhadinovirus lineage have likely been driven by selective pressures to disseminate within and colonize the host. Identification of the shared host processes that are targeted by the diverse family of vFGARATs may reveal novel targets for therapeutic agents to prevent life-long infections by these oncogenic viruses.
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Affiliation(s)
- Nick D. Van Skike
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Nana K. Minkah
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Chad H. Hogan
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
- Graduate Program of Genetics, Stony Brook University, Stony Brook, New York, United States of America
| | - Gary Wu
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Peter T. Benziger
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | | | - Mehmet Kara
- Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Deborah M. Kim-Holzapfel
- Departments of Chemistry and of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Douglas W. White
- Gundersen Health System, La Crosse, Wisconsin, United States of America
| | - Scott A. Tibbetts
- Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Jarrod B. French
- Departments of Chemistry and of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Laurie T. Krug
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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Novel Role of vBcl2 in the Virion Assembly of Kaposi's Sarcoma-Associated Herpesvirus. J Virol 2018; 92:JVI.00914-17. [PMID: 29167347 DOI: 10.1128/jvi.00914-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022] Open
Abstract
The viral Bcl-2 homolog (vBcl2) of Kaposi's sarcoma-associated herpesvirus (KSHV) displays efficient antiapoptotic and antiautophagic activity through its central BH3 domain, which functions to prolong the life span of virus-infected cells and ultimately enhances virus replication and latency. Independent of its antiapoptotic and antiautophagic activity, vBcl2 also plays an essential role in KSHV lytic replication through its amino-terminal amino acids (aa) 11 to 20. Here, we report a novel molecular mechanism of vBcl2-mediated regulation of KSHV lytic replication. vBcl2 specifically bound the tegument protein open reading frame 55 (ORF55) through its amino-terminal aa 11 to 20, allowing their association with virions. Consequently, the vBcl2 peptide derived from vBcl2 aa 11 to 20 effectively disrupted the interaction between vBcl2 and ORF55, inhibiting the incorporation of the ORF55 tegument protein into virions. This study provides new insight into vBcl2's function in KSHV virion assembly that is separable from its inhibitory role in host apoptosis and autophagy.IMPORTANCE KSHV, an important human pathogen accounting for a large percentage of virally caused cancers worldwide, has evolved a variety of stratagems for evading host immune responses to establish lifelong persistent infection. Upon viral infection, infected cells can go through programmed cell death, including apoptosis and autophagy, which plays an effective role in antiviral responses. To counter the host response, KSHV vBcl2 efficiently blocks apoptosis and autophagy to persist for the life span of virus-infected cells. Besides its anti-programmed-cell-death activity, vBcl2 also interacts with the ORF55 tegument protein for virion assembly in infected cells. Interestingly, the vBcl2 peptide disrupts the vBcl2-ORF55 interaction and effectively inhibits KSHV virion assembly. This study indicates that KSHV vBcl2 harbors at least three genetically separable functions to modulate both host cell death signaling and virion production and that the vBcl2 peptide can be developed as an anti-KSHV therapeutic application.
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Epstein-Barr Virus BKRF4 Gene Product Is Required for Efficient Progeny Production. J Virol 2017; 91:JVI.00975-17. [PMID: 28904200 DOI: 10.1128/jvi.00975-17] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/08/2017] [Indexed: 12/14/2022] Open
Abstract
Epstein-Barr virus (EBV), a member of human gammaherpesvirus, infects mainly B cells. EBV has two alternative life cycles, latent and lytic, and is reactivated occasionally from the latent stage to the lytic cycle. To combat EBV-associated disorders, understanding the molecular mechanisms of the EBV lytic replication cycle is also important. Here, we focused on an EBV lytic gene, BKRF4. Using our anti-BKRF4 antibody, we revealed that the BKRF4 gene product is expressed during the lytic cycle with late kinetics. To characterize the role of BKRF4, we constructed BKRF4-knockout mutants using the bacterial artificial chromosome (BAC) and CRISPR/Cas9 systems. Although disruption of the BKRF4 gene had almost no effect on viral protein expression and DNA synthesis, it significantly decreased progeny virion levels in HEK293 and Akata cells. Furthermore, we show that BKRF4 is involved not only in production of progeny virions but also in increasing the infectivity of the virus particles. Immunoprecipitation assays revealed that BKRF4 interacted with a virion protein, BGLF2. We showed that the C-terminal region of BKRF4 was critical for this interaction and for efficient progeny production. Immunofluorescence analysis revealed that BKRF4 partially colocalized with BGLF2 in the nucleus and perinuclear region. Finally, we showed that BKRF4 is a phosphorylated, possible tegument protein and that the EBV protein kinase BGLF4 may be important for this phosphorylation. Taken together, our data suggest that BKRF4 is involved in the production of infectious virions.IMPORTANCE Although the latent genes of EBV have been studied extensively, the lytic genes are less well characterized. This study focused on one such lytic gene, BKRF4, which is conserved only among gammaherpesviruses (ORF45 of Kaposi's sarcoma-associated herpesvirus or murine herpesvirus 68). After preparing the BKRF4 knockout virus using B95-8 EBV-BAC, we demonstrated that the BKRF4 gene was involved in infectious progeny particle production. Importantly, we successfully generated a BKRF4 knockout virus of Akata using CRISPR/Cas9 technology, confirming the phenotype in this separate strain. We further showed that BKRF4 interacted with another virion protein, BGLF2, and demonstrated the importance of this interaction in infectious virion production. These results shed light on the elusive process of EBV progeny maturation in the lytic cycle. Notably, this study describes a successful example of the generation and characterization of an EBV construct with a disrupted lytic gene using CRISPR/Cas9 technology.
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