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Dunn LEM, Birkenheuer CH, Baines JD. A Revision of Herpes Simplex Virus Type 1 Transcription: First, Repress; Then, Express. Microorganisms 2024; 12:262. [PMID: 38399666 PMCID: PMC10892140 DOI: 10.3390/microorganisms12020262] [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: 12/15/2023] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 02/25/2024] Open
Abstract
The herpes virus genome bears more than 80 strong transcriptional promoters. Upon entry into the host cell nucleus, these genes are transcribed in an orderly manner, producing five immediate-early (IE) gene products, including ICP0, ICP4, and ICP22, while non-IE genes are mostly silent. The IE gene products are necessary for the transcription of temporal classes following sequentially as early, leaky late, and true late. A recent analysis using precision nuclear run-on followed by deep sequencing (PRO-seq) has revealed an important step preceding all HSV-1 transcription. Specifically, the immediate-early proteins ICP4 and ICP0 enter the cell with the incoming genome to help preclude the nascent antisense, intergenic, and sense transcription of all viral genes. VP16, which is also delivered into the nucleus upon entry, almost immediately reverses this repression on IE genes. The resulting de novo expression of ICP4 and ICP22 further repress antisense, intergenic, and early and late viral gene transcription through different mechanisms before the sequential de-repression of these gene classes later in infection. This early repression, termed transient immediate-early protein-mediated repression (TIEMR), precludes unproductive, antisense, intergenic, and late gene transcription early in infection to ensure the efficient and orderly progression of the viral cascade.
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Affiliation(s)
- Laura E M Dunn
- Baker Institute for Animal Health, Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14850, USA
| | - Claire H Birkenheuer
- Baker Institute for Animal Health, Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14850, USA
| | - Joel D Baines
- Baker Institute for Animal Health, Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14850, USA
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2
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Zhao Z, Liu X, Zong Y, Shi X, Sun Y. Cellular Processes Induced by HSV-1 Infections in Vestibular Neuritis. Viruses 2023; 16:12. [PMID: 38275947 PMCID: PMC10819745 DOI: 10.3390/v16010012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/18/2023] [Accepted: 12/19/2023] [Indexed: 01/27/2024] Open
Abstract
Herpesvirus is a prevalent pathogen that primarily infects human epithelial cells and has the ability to reside in neurons. In the field of otolaryngology, herpesvirus infection primarily leads to hearing loss and vestibular neuritis and is considered the primary hypothesis regarding the pathogenesis of vestibular neuritis. In this review, we provide a summary of the effects of the herpes virus on cellular processes in both host cells and immune cells, with a focus on HSV-1 as illustrative examples.
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Affiliation(s)
- Zhengdong Zhao
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (Z.Z.); (X.L.); (Y.Z.); (X.S.)
| | - Xiaozhou Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (Z.Z.); (X.L.); (Y.Z.); (X.S.)
| | - Yanjun Zong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (Z.Z.); (X.L.); (Y.Z.); (X.S.)
| | - Xinyu Shi
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (Z.Z.); (X.L.); (Y.Z.); (X.S.)
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (Z.Z.); (X.L.); (Y.Z.); (X.S.)
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan 430022, China
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3
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Subedi S, Nag N, Shukla H, Padhi AK, Tripathi T. Comprehensive analysis of liquid-liquid phase separation propensities of HSV-1 proteins and their interaction with host factors. J Cell Biochem 2023. [PMID: 37796176 DOI: 10.1002/jcb.30480] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/08/2023] [Accepted: 09/17/2023] [Indexed: 10/06/2023]
Abstract
In recent years, it has been shown that the liquid-liquid phase separation (LLPS) of virus proteins plays a crucial role in their life cycle. It promotes the formation of viral replication organelles, concentrating viral components for efficient replication and facilitates the assembly of viral particles. LLPS has emerged as a crucial process in the replication and assembly of herpes simplex virus-1 (HSV-1). Recent studies have identified several HSV-1 proteins involved in LLPS, including the myristylated tegument protein UL11 and infected cell protein 4; however, a complete proteome-level understanding of the LLPS-prone HSV-1 proteins is not available. We provide a comprehensive analysis of the HSV-1 proteome and explore the potential of its proteins to undergo LLPS. By integrating sequence analysis, prediction algorithms and an array of tools and servers, we identified 10 HSV-1 proteins that exhibit high LLPS potential. By analysing the amino acid sequences of the LLPS-prone proteins, we identified specific sequence motifs and enriched amino acid residues commonly found in LLPS-prone regions. Our findings reveal a diverse range of LLPS-prone proteins within the HSV-1, which are involved in critical viral processes such as replication, transcriptional regulation and assembly of viral particles. This suggests that LLPS might play a crucial role in facilitating the formation of specialized viral replication compartments and the assembly of HSV-1 virion. The identification of LLPS-prone proteins in HSV-1 opens up new avenues for understanding the molecular mechanisms underlying viral pathogenesis. Our work provides valuable insights into the LLPS landscape of HSV-1, highlighting potential targets for further experimental validation and enhancing our understanding of viral replication and pathogenesis.
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Affiliation(s)
- Sushma Subedi
- Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong, India
| | - Niharika Nag
- Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong, India
| | - Harish Shukla
- Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong, India
| | - Aditya K Padhi
- Laboratory for Computational Biology & Biomolecular Design, School of Biochemical Engineering, Indian Institute of Technology (BHU), Varanasi, India
| | - Timir Tripathi
- Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong, India
- Department of Zoology, North-Eastern Hill University, Shillong, India
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4
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Jansens RJ, Olarerin-George A, Verhamme R, Mirza A, Jaffrey S, Favoreel HW. Alphaherpesvirus-mediated remodeling of the cellular transcriptome results in depletion of m6A-containing transcripts. iScience 2023; 26:107310. [PMID: 37575180 PMCID: PMC10415716 DOI: 10.1016/j.isci.2023.107310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 06/04/2023] [Accepted: 07/04/2023] [Indexed: 08/15/2023] Open
Abstract
The mechanisms by which viruses regulate host mRNAs during infection are still poorly understood. Several host transcripts that encode proteins that contribute to the anti-viral response contain the N6-methyladenosine nucleotide (m6A). In this study, we investigated if and how viruses from different (sub) families specifically affect m6A-containing host transcripts. Systematic analysis of host transcriptomes after infection with diverse types of viruses showed that m6A-methylated transcripts are selectively downregulated during infection with Sendai virus, African swine fever virus and the alphaherpesviruses herpes simplex virus 1 (HSV-1) and pseudorabies virus (PRV). Focusing on PRV and HSV-1, we found that downregulation of m6A-methylated transcripts depends on the YTHDF family of m6A-binding proteins, and correlates with localization of these proteins to enlarged P-bodies. Knockdown of YTHDF proteins in primary cells reduced PRV protein expression and increased expression of antiviral interferon-stimulated genes, suggesting that virus-induced depletion of host m6A-containing transcripts constitutes an immune evasion strategy.
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Affiliation(s)
- Robert J.J. Jansens
- Department of Translational Physiology, Infectiology and Public Health
- Department of Pharmacology, Weill Medical College, Cornell University, New York NY 10021, USA
| | - Anthony Olarerin-George
- Department of Pharmacology, Weill Medical College, Cornell University, New York NY 10021, USA
| | - Ruth Verhamme
- Department of Translational Physiology, Infectiology and Public Health
| | - Aashiq Mirza
- Department of Pharmacology, Weill Medical College, Cornell University, New York NY 10021, USA
| | - Samie Jaffrey
- Department of Pharmacology, Weill Medical College, Cornell University, New York NY 10021, USA
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5
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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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6
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Liu Y, Yao Z, Lian G, Yang P. Biomolecular phase separation in stress granule assembly and virus infection. Acta Biochim Biophys Sin (Shanghai) 2023; 55:1099-1118. [PMID: 37401177 PMCID: PMC10415189 DOI: 10.3724/abbs.2023117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/06/2023] [Indexed: 07/05/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) has emerged as a crucial mechanism for cellular compartmentalization. One prominent example of this is the stress granule. Found in various types of cells, stress granule is a biomolecular condensate formed through phase separation. It comprises numerous RNA and RNA-binding proteins. Over the past decades, substantial knowledge has been gained about the composition and dynamics of stress granules. SGs can regulate various signaling pathways and have been associated with numerous human diseases, such as neurodegenerative diseases, cancer, and infectious diseases. The threat of viral infections continues to loom over society. Both DNA and RNA viruses depend on host cells for replication. Intriguingly, many stages of the viral life cycle are closely tied to RNA metabolism in human cells. The field of biomolecular condensates has rapidly advanced in recent times. In this context, we aim to summarize research on stress granules and their link to viral infections. Notably, stress granules triggered by viral infections behave differently from the canonical stress granules triggered by sodium arsenite (SA) and heat shock. Studying stress granules in the context of viral infections could offer a valuable platform to link viral replication processes and host anti-viral responses. A deeper understanding of these biological processes could pave the way for innovative interventions and treatments for viral infectious diseases. They could potentially bridge the gap between basic biological processes and interactions between viruses and their hosts.
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Affiliation(s)
- Yi Liu
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| | - Zhiying Yao
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| | - Guiwei Lian
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| | - Peiguo Yang
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
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7
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Zhang B, Ding J, Ma Z. ICP4-Associated Activation of Rap1b Facilitates Herpes Simplex Virus Type I (HSV-1) Infection in Human Corneal Epithelial Cells. Viruses 2023; 15:1457. [PMID: 37515145 PMCID: PMC10385634 DOI: 10.3390/v15071457] [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: 06/02/2023] [Revised: 06/25/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023] Open
Abstract
The strong contribution of RAS-related protein 1b (Rap1b) to cytoskeleton remodeling determines intracellular and extracellular physiological activities, including the successful infection of viruses in permissive cells, but its role in the HSV-1 life cycle is still unclear. Here, we demonstrated that the HSV-1 immediate early (IE) gene ICP4 inhibits protein kinase A (PKA) phosphorylation to induce Rap1b-activation-mediated viral infection. Rap1b activation and membrane enrichment begin at the early stage of HSV-1 infection and remain active during the proliferation period of the virus. Treating the cells with Rap1b small interfering RNA (siRNA) showed a dose-dependent decrease in viral infection levels, but no dose-dependent increase was observed after Rap1b overexpression. Further investigation indicated that the suppression of Rap1b activation derives from phosphorylated PKA and Rap1b mutants with partial or complete prenylation instead of phosphorylation, which promoted viral infection in a dose-dependent manner. Furthermore, the PKA agonist Forskolin disturbed Rap1b activation in a dose-dependent manner, accompanied by a decreasing trend in viral infection. Moreover, the HSV-1 IE gene ICP4 induced PKA dephosphorylation, leading to continuous Rap1b activation, followed by cytoskeleton rearrangement induced by cell division control protein 42 (CDC42) and Ras-related C3 botulinum toxin substrate 1 (RAC1). These further stimulated membrane-triggered physiological processes favoring virus infection. Altogether, we show the significance of Rap1b during HSV-1 infection and uncover the viral infection mechanism determined by the posttranslational regulation of the viral ICP4 gene and Rap1b host protein.
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Affiliation(s)
- Beibei Zhang
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China
| | - Juntao Ding
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China
| | - Zhenghai Ma
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China
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8
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Yang S, Shen W, Hu J, Cai S, Zhang C, Jin S, Guan X, Wu J, Wu Y, Cui J. Molecular mechanisms and cellular functions of liquid-liquid phase separation during antiviral immune responses. Front Immunol 2023; 14:1162211. [PMID: 37251408 PMCID: PMC10210139 DOI: 10.3389/fimmu.2023.1162211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 04/25/2023] [Indexed: 05/31/2023] Open
Abstract
Spatiotemporal separation of cellular components is vital to ensure biochemical processes. Membrane-bound organelles such as mitochondria and nuclei play a major role in isolating intracellular components, while membraneless organelles (MLOs) are accumulatively uncovered via liquid-liquid phase separation (LLPS) to mediate cellular spatiotemporal organization. MLOs orchestrate various key cellular processes, including protein localization, supramolecular assembly, gene expression, and signal transduction. During viral infection, LLPS not only participates in viral replication but also contributes to host antiviral immune responses. Therefore, a more comprehensive understanding of the roles of LLPS in virus infection may open up new avenues for treating viral infectious diseases. In this review, we focus on the antiviral defense mechanisms of LLPS in innate immunity and discuss the involvement of LLPS during viral replication and immune evasion escape, as well as the strategy of targeting LLPS to treat viral infectious diseases.
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Affiliation(s)
- Shuai Yang
- The First Affiliated Hospital of Sun Yat-sen University, Ministry of Education MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Weishan Shen
- Department of Critical Care Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jiajia Hu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Sihui Cai
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Chenqiu Zhang
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Shouheng Jin
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xiangdong Guan
- Department of Critical Care Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jianfeng Wu
- Department of Critical Care Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Yaoxing Wu
- The First Affiliated Hospital of Sun Yat-sen University, Ministry of Education MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
- Department of Critical Care Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jun Cui
- The First Affiliated Hospital of Sun Yat-sen University, Ministry of Education MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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9
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Wang H, Liu S, Lv Y, Wei W. Codon usage bias of Venezuelan equine encephalitis virus and its host adaption. Virus Res 2023; 328:199081. [PMID: 36854361 DOI: 10.1016/j.virusres.2023.199081] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 09/14/2022] [Accepted: 02/24/2023] [Indexed: 03/02/2023]
Abstract
Venezuelan equine encephalitis virus (VEEV) is an emerging zoonotic virus in the alphavirus genus. It can be transmitted to humans due to spillover from equid-mosquito cycles. The symptoms caused by VEEV include fever, headache, myalgia, nausea, and vomiting. It can also cause encephalitis in severe cases. The evolutionary features of VEEV are largely unknown. In this study, we comprehensively analyzed the codon usage pattern of VEEV by computing a variety of indicators, such as effective number of codons (ENc), codon adaptation index (CAI), relative synonymous codon usage (RSCU), on 130 VEEV coding sequences retrieved from GenBank. The results showed that the codon usage bias of VEEV is relatively low. ENc-GC3s plot, neutrality plot, and CAI-ENc correlation analyses supported that translational selection plays an important role in shaping the codon usage pattern of VEEV whereas the mutation pressure has a minor influence. Analysis of RSCU values showed that most of the preferred codons in VEEV are C/G-ended. Analysis of dinucleotide composition found that all CG- and UA-containing codons are not preferentially used. Phylogenetic analysis showed that VEEV isolates can be clustered into three genera and evolutionary force affects the codon usage pattern. Furthermore, a correspondence analysis (COA) showed that aromaticity and hydrophobicity as well as geographical distribution also have certain effects on the codon usage variation of VEEV, suggesting the possible involvement of translational selection. Overall, the codon usage of VEEV is comparatively slight and translational selection might be the main factor that shapes the codon usage pattern of VEEV. This study will promote our understanding about the evolution of VEEV and its host adaption, and might provide some clues for preventing the cross-species transmission of VEEV.
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Affiliation(s)
- Hongju Wang
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
| | - Shijie Liu
- School of Clinical Medicine, Henan University, Kaifeng, China
| | - Yao Lv
- School of Clinical Medicine, Henan University, Kaifeng, China
| | - Wenqiang Wei
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China.
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Membraneless Compartmentalization of Nuclear Assembly Sites during Murine Cytomegalovirus Infection. Viruses 2023; 15:v15030766. [PMID: 36992475 PMCID: PMC10053344 DOI: 10.3390/v15030766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/28/2023] [Accepted: 03/14/2023] [Indexed: 03/19/2023] Open
Abstract
Extensive reorganization of infected cells and the formation of large structures known as the nuclear replication compartment (RC) and cytoplasmic assembly compartment (AC) is a hallmark of beta-herpesvirus infection. These restructurings rely on extensive compartmentalization of the processes that make up the virus manufacturing chain. Compartmentalization of the nuclear processes during murine cytomegalovirus (MCMV) infection is not well described. In this study, we visualized five viral proteins (pIE1, pE1, pM25, pm48.2, and pM57) and replicated viral DNA to reveal the nuclear events during MCMV infection. As expected, these events can be matched with those described for other beta and alpha herpesviruses and contribute to the overall picture of herpesvirus assembly. Imaging showed that four viral proteins (pE1, pM25, pm48.2, and pM57) and replicated viral DNA condense in the nucleus into membraneless assemblies (MLAs) that undergo a maturation sequence to form the RC. One of these proteins (pM25), which is also expressed in a cytoplasmic form (pM25l), showed similar MLAs in the AC. Bioinformatics tools for predicting biomolecular condensates showed that four of the five proteins had a high propensity for liquid–liquid phase separation (LLPS), suggesting that LLPS may be a mechanism for compartmentalization within RC and AC. Examination of the physical properties of MLAs formed during the early phase of infection by 1,6-hexanediol treatment in vivo revealed liquid-like properties of pE1 MLAs and more solid-like properties of pM25 MLAs, indicating heterogeneity of mechanisms in the formation of virus-induced MLAs. Analysis of the five viral proteins and replicated viral DNA shows that the maturation sequence of RC and AC is not completed in many cells, suggesting that virus production and release is carried out by a rather limited number of cells. This study thus lays the groundwork for further investigation of the replication cycle of beta-herpesviruses, and the results should be incorporated into plans for high-throughput and single-cell analytic approaches.
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12
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Liaisons dangereuses: Intrinsic Disorder in Cellular Proteins Recruited to Viral Infection-Related Biocondensates. Int J Mol Sci 2023; 24:ijms24032151. [PMID: 36768473 PMCID: PMC9917183 DOI: 10.3390/ijms24032151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/11/2023] [Accepted: 01/19/2023] [Indexed: 01/25/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) is responsible for the formation of so-called membrane-less organelles (MLOs) that are essential for the spatio-temporal organization of the cell. Intrinsically disordered proteins (IDPs) or regions (IDRs), either alone or in conjunction with nucleic acids, are involved in the formation of these intracellular condensates. Notably, viruses exploit LLPS at their own benefit to form viral replication compartments. Beyond giving rise to biomolecular condensates, viral proteins are also known to partition into cellular MLOs, thus raising the question as to whether these cellular phase-separating proteins are drivers of LLPS or behave as clients/regulators. Here, we focus on a set of eukaryotic proteins that are either sequestered in viral factories or colocalize with viral proteins within cellular MLOs, with the primary goal of gathering organized, predicted, and experimental information on these proteins, which constitute promising targets for innovative antiviral strategies. Using various computational approaches, we thoroughly investigated their disorder content and inherent propensity to undergo LLPS, along with their biological functions and interactivity networks. Results show that these proteins are on average, though to varying degrees, enriched in disorder, with their propensity for phase separation being correlated, as expected, with their disorder content. A trend, which awaits further validation, tends to emerge whereby the most disordered proteins serve as drivers, while more ordered cellular proteins tend instead to be clients of viral factories. In light of their high disorder content and their annotated LLPS behavior, most proteins in our data set are drivers or co-drivers of molecular condensation, foreshadowing a key role of these cellular proteins in the scaffolding of viral infection-related MLOs.
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Chung WC, Ahn JH, Song MJ. Liquid-liquid phase separation drives herpesvirus assembly in the cytoplasm. J Cell Biol 2023; 222:e202211015. [PMID: 36542408 PMCID: PMC9779906 DOI: 10.1083/jcb.202211015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Liquid-liquid phase separation (LLPS) has emerged as a fundamental mechanism to compartmentalize biomolecules into membraneless organelles. In this issue, Zhou et al. (2022. J. Cell Biol.https://doi.org/10.1083/jcb.202201088), report that MHV-68 ORF52 undergoes LLPS to form cytoplasmic virion assembly compartments, regulating the spatiotemporal compartmentalization of viral components.
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Affiliation(s)
- Woo-Chang Chung
- Department of Microbiology, Graduate School of Basic Medical Science, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Jin-Hyun Ahn
- Department of Microbiology, Graduate School of Basic Medical Science, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Moon Jung Song
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
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14
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Two-Color CRISPR Imaging Reveals Dynamics of Herpes Simplex Virus 1 Replication Compartments and Virus-Host Interactions. J Virol 2022; 96:e0092022. [PMID: 36453882 PMCID: PMC9769385 DOI: 10.1128/jvi.00920-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Real-time imaging tools for single-virus tracking provide spatially resolved, quantitative measurements of viral replication and virus-host interactions. However, efficiently labeling both parental and progeny viruses in living host cells remains challenging. Here, we developed a novel strategy using the CRISPR-Tag system to detect herpes simplex virus 1 (HSV-1) DNA in host cells. We created recombinant HSV-1 harboring an ~600-bp CRISPR-Tag sequence which can be sufficiently recognized by dCas9-fluorescent protein (FP) fusion proteins. CRISPR-assisted single viral genome tracking (CASVIT) allows us to assess the temporal and spatial information of viral replication at the single-cell level. Combining the advantages of SunTag and tandem split green fluorescent protein (GFP) in amplifying fluorescent signals, dSaCas9-tdTomato10x and dSpCas9-GFP14x were constructed to enable efficient two-color CASVIT detection. Real-time two-color imaging indicates that replication compartments (RCs) frequently come into contact with each other but do not mix, suggesting that RC territory is highly stable. Last, two-color CASVIT enables simultaneous tracking of viral DNA and host chromatin, which reveals that a dramatic loss of telomeric and centromeric DNA occurs in host cells at the early stage of viral replication. Overall, our work has established a framework for developing CRISPR-Cas9-based imaging tools to study DNA viruses in living cells. IMPORTANCE Herpes simplex virus 1 (HSV-1), a representative of the family Herpesviridae, is a ubiquitous pathogen that can establish lifelong infections and widely affects human health. Viral infection is a dynamic process that involves many steps and interactions with various cellular structures, including host chromatin. A common viral replication strategy is to form RCs that concentrate factors required for viral replication. Efficient strategies for imaging the dynamics of viral genomes, RC formation, and the interaction between the virus and host offer the opportunity to dissect the steps of the infection process and determine the mechanism underlying each step. We have developed an efficient two-color imaging system based on CRISPR-Cas9 technology to detect HSV-1 genomes quantitatively in living cells. Our results shed light on novel aspects of RC dynamics and virus-host interactions.
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Immediate Early Proteins of Herpes Simplex Virus Transiently Repress Viral Transcription before Subsequent Activation. J Virol 2022; 96:e0141622. [PMID: 36300939 PMCID: PMC9683018 DOI: 10.1128/jvi.01416-22] [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
HSV-1 transcription during productive replication is believed to comprise a series of activation steps leading to a specific sequence of gene expression. Here, we show that virion components and IE gene products ICP0, ICP4, and ICP22 first repress viral gene transcription to various degrees before subsequently activating specific gene subsets.
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Knipe DM, Prichard A, Sharma S, Pogliano J. Replication Compartments of Eukaryotic and Bacterial DNA Viruses: Common Themes Between Different Domains of Host Cells. Annu Rev Virol 2022; 9:307-327. [PMID: 36173697 DOI: 10.1146/annurev-virology-012822-125828] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Subcellular organization is essential for life. Cells organize their functions into organelles to concentrate their machinery and supplies for optimal efficiency. Likewise, viruses organize their replication machinery into compartments or factories within their host cells for optimal replicative efficiency. In this review, we discuss how DNA viruses that infect both eukaryotic cells and bacteria assemble replication compartments for synthesis of progeny viral DNA and transcription of the viral genome. Eukaryotic DNA viruses assemble replication compartments in the nucleus of the host cell while DNA bacteriophages assemble compartments called phage nuclei in the bacterial cytoplasm. Thus, DNA viruses infecting host cells from different domains of life share common replication strategies.
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Affiliation(s)
- David M Knipe
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA;
| | - Amy Prichard
- Division of Biological Sciences, University of California, San Diego, La Jolla, California, USA;
| | - Surendra Sharma
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA;
| | - Joe Pogliano
- Division of Biological Sciences, University of California, San Diego, La Jolla, California, USA;
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Wei W, Bai L, Yan B, Meng W, Wang H, Zhai J, Si F, Zheng C. When liquid-liquid phase separation meets viral infections. Front Immunol 2022; 13:985622. [PMID: 36016945 PMCID: PMC9395683 DOI: 10.3389/fimmu.2022.985622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 07/20/2022] [Indexed: 11/17/2022] Open
Abstract
Eukaryotic cells have both membranous and membraneless organelles. While the formation mechanism of membranous organelles is well understood, the formation mechanism of membraneless organelles remains unknown. Many biomolecules in the cytoplasm transition from the liquid phase to the agglutinated phase are known as liquid-liquid phase separation (LLPS). The biomolecular agglomerates’ physical properties enable them to function as dynamic compartments that respond to external pressures and stimuli. Scientists have gradually recognized the importance of phase separation during viral infections. LLPS provides a powerful new framework for understanding the viral life cycle from viral replication to evasion of host immune surveillance. As a result, this review focuses on the progress of LLPS research in viral infection and immune regulation to provide clues for antiviral therapeutic strategies.
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Affiliation(s)
- Wenqiang Wei
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
| | - Lu Bai
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Bing Yan
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
| | - Weiquan Meng
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
| | - Hongju Wang
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
| | - Jingbo Zhai
- Medical College, Inner Mongolia Minzu University, Tongliao, China
- Key Laboratory of Zoonose Prevention and Control at Universities of Inner Mongolia Autonomous Region, Tongliao, China
| | - Fusheng Si
- Institute of Animal Science and Veterinary Medicine, Shanghai Key Laboratory of Agricultural Genetics and Breeding, Shanghai Engineering Research Center of Breeding Pig, Shanghai Academy of Agricultural Sciences, Shanghai, China
- *Correspondence: Chunfu Zheng, ; Fusheng Si,
| | - Chunfu Zheng
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
- *Correspondence: Chunfu Zheng, ; Fusheng Si,
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Caragliano E, Brune W, Bosse JB. Herpesvirus Replication Compartments: Dynamic Biomolecular Condensates? Viruses 2022; 14:960. [PMID: 35632702 PMCID: PMC9147375 DOI: 10.3390/v14050960] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 05/01/2022] [Indexed: 02/01/2023] Open
Abstract
Recent progress has provided clear evidence that many RNA-viruses form cytoplasmic biomolecular condensates mediated by liquid-liquid phase separation to facilitate their replication. In contrast, seemingly contradictory data exist for herpesviruses, which replicate their DNA genomes in nuclear membrane-less replication compartments (RCs). Here, we review the current literature and comment on nuclear condensate formation by herpesviruses, specifically with regard to RC formation. Based on data obtained with human cytomegalovirus (human herpesvirus 5), we propose that liquid and homogenous early RCs convert into more heterogeneous RCs with complex properties over the course of infection. We highlight how the advent of DNA replication leads to the maturation of these biomolecular condensates, likely by adding an additional DNA scaffold.
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Affiliation(s)
- Enrico Caragliano
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany;
- Centre for Structural Systems Biology, 22607 Hamburg, Germany
- Institute of Virology, Hannover Medical School, 30625 Hannover, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, 30625 Hannover, Germany
| | - Wolfram Brune
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany;
- German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel-Riems, 38124 Braunschweig, Germany
| | - Jens B. Bosse
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany;
- Centre for Structural Systems Biology, 22607 Hamburg, Germany
- Institute of Virology, Hannover Medical School, 30625 Hannover, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, 30625 Hannover, Germany
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Replication Compartments-The Great Survival Strategy for Epstein-Barr Virus Lytic Replication. Microorganisms 2022; 10:microorganisms10050896. [PMID: 35630341 PMCID: PMC9144946 DOI: 10.3390/microorganisms10050896] [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: 03/24/2022] [Revised: 04/14/2022] [Accepted: 04/23/2022] [Indexed: 12/04/2022] Open
Abstract
During Epstein–Barr virus (EBV) lytic replication, viral DNA synthesis is carried out in viral replication factories called replication compartments (RCs), which are located at discrete sites in the nucleus. Viral proteins constituting the viral replication machinery are accumulated in the RCs to amplify viral genomes. Newly synthesized viral DNA is stored in a subdomain of the RC termed the BMRF1-core, matured by host factors, and finally packed into assembled viral capsids. Late (L) genes are transcribed from DNA stored in the BMRF1-core through a process that is mainly dependent on the viral pre-initiation complex (vPIC). RC formation is a well-regulated system and strongly advantageous for EBV survival because of the following aspects: (1) RCs enable the spatial separation of newly synthesized viral DNA from the cellular chromosome for protection and maturation of viral DNA; (2) EBV-coded proteins and their interaction partners are recruited to RCs, which enhances the interactions among viral proteins, cellular proteins, and viral DNA; (3) the formation of RCs benefits continuous replication, leading to L gene transcription; and (4) DNA storage and maturation leads to efficient progeny viral production. Here, we review the state of knowledge of this important viral structure and discuss its roles in EBV survival.
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Caragliano E, Bonazza S, Frascaroli G, Tang J, Soh TK, Grünewald K, Bosse JB, Brune W. Human cytomegalovirus forms phase-separated compartments at viral genomes to facilitate viral replication. Cell Rep 2022; 38:110469. [PMID: 35263605 PMCID: PMC8924372 DOI: 10.1016/j.celrep.2022.110469] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 11/29/2021] [Accepted: 02/10/2022] [Indexed: 12/21/2022] Open
Abstract
Human cytomegalovirus (HCMV) replicates its DNA genome in specialized replication compartments (RCs) in the host cell nucleus. These membrane-less organelles originate as spherical structures and grow in size over time. However, the mechanism of RC biogenesis has remained understudied. Using live-cell imaging and photo-oligomerization, we show that a central component of RCs, the UL112-113 proteins, undergo liquid-liquid phase separation (LLPS) to form RCs in the nucleus. We show that the self-interacting domain and large intrinsically disordered regions of UL112-113 are required for LLPS. Importantly, viral DNA induces local clustering of these proteins and lowers the threshold for phase separation. The formation of phase-separated compartments around viral genomes is necessary to recruit the viral DNA polymerase for viral genome replication. Thus, HCMV uses its UL112-113 proteins to generate RCs around viral genomes by LLPS to ensure the formation of a pro-replicative environment.
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Affiliation(s)
- Enrico Caragliano
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; Centre for Structural Systems Biology, 22607 Hamburg, Germany; Institute of Virology, Hannover Medical School, 30625 Hannover, Germany
| | - Stefano Bonazza
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany
| | - Giada Frascaroli
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany
| | - Jiajia Tang
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany
| | - Timothy K Soh
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; Centre for Structural Systems Biology, 22607 Hamburg, Germany; Institute of Virology, Hannover Medical School, 30625 Hannover, Germany; Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Kay Grünewald
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; Centre for Structural Systems Biology, 22607 Hamburg, Germany; Institute of Biochemistry and Molecular Biology, University of Hamburg, 20146 Hamburg, Germany; Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Jens B Bosse
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; Centre for Structural Systems Biology, 22607 Hamburg, Germany; Institute of Virology, Hannover Medical School, 30625 Hannover, Germany; Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany.
| | - Wolfram Brune
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel-Riems, Hamburg, Germany.
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21
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Vychodil T, Wight DJ, Nascimento M, Jolmes F, Korte T, Herrmann A, Kaufer BB. Visualization of Marek’s Disease Virus Genomes in Living Cells during Lytic Replication and Latency. Viruses 2022; 14:v14020287. [PMID: 35215880 PMCID: PMC8877148 DOI: 10.3390/v14020287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/24/2022] [Accepted: 01/26/2022] [Indexed: 11/18/2022] Open
Abstract
Visualization of the herpesvirus genomes during lytic replication and latency is mainly achieved by fluorescence in situ hybridization (FISH). Unfortunately, this technique cannot be used for the real-time detection of viral genome in living cells. To facilitate the visualization of the Marek’s disease virus (MDV) genome during all stages of the virus lifecycle, we took advantage of the well-established tetracycline operator/repressor (TetO/TetR) system. This system consists of a fluorescently labeled TetR (TetR-GFP) that specifically binds to an array of tetO sequences. This tetO repeat array was first inserted into the MDV genome (vTetO). Subsequently, we fused TetR-GFP via a P2a self-cleaving peptide to the C-terminus of the viral interleukin 8 (vIL8), which is expressed during lytic replication and latency. Upon reconstitution of this vTetO-TetR virus, fluorescently labeled replication compartments were detected in the nucleus during lytic replication. After validating the specificity of the observed signal, we used the system to visualize the genesis and mobility of the viral replication compartments. In addition, we assessed the infection of nuclei in syncytia as well as lytic replication and latency in T cells. Taken together, we established a system allowing us to track the MDV genome in living cells that can be applied to many other DNA viruses.
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Affiliation(s)
- Tereza Vychodil
- Institut für Virologie, Freie Universität Berlin, Robert von Ostertag-Straße 7-13, 14163 Berlin, Germany; (T.V.); (D.J.W.); (M.N.)
| | - Darren J. Wight
- Institut für Virologie, Freie Universität Berlin, Robert von Ostertag-Straße 7-13, 14163 Berlin, Germany; (T.V.); (D.J.W.); (M.N.)
| | - Mariana Nascimento
- Institut für Virologie, Freie Universität Berlin, Robert von Ostertag-Straße 7-13, 14163 Berlin, Germany; (T.V.); (D.J.W.); (M.N.)
| | - Fabian Jolmes
- Department of Biology, Molecular Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115 Berlin, Germany; (F.J.); (T.K.); (A.H.)
| | - Thomas Korte
- Department of Biology, Molecular Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115 Berlin, Germany; (F.J.); (T.K.); (A.H.)
| | - Andreas Herrmann
- Department of Biology, Molecular Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115 Berlin, Germany; (F.J.); (T.K.); (A.H.)
- Institut für Chemie und Biochemie, Freie Universität Berlin, Altensteinstr. 23a, 14195 Berlin, Germany
| | - Benedikt B. Kaufer
- Institut für Virologie, Freie Universität Berlin, Robert von Ostertag-Straße 7-13, 14163 Berlin, Germany; (T.V.); (D.J.W.); (M.N.)
- Veterinary Centre for Resistance Research (TZR), Freie Universität Berlin, 14163 Berlin, Germany
- Correspondence: ; Tel.: +49-30-838-51936
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Abstract
Viruses have evolved precise mechanisms for using the cellular physiological pathways for their perpetuation. These virus-driven biochemical events must be separated in space and time from those of the host cell. In recent years, granular structures, known for over a century for rabies virus, were shown to host viral gene function and were named using terms such as viroplasms, replication sites, inclusion bodies, or viral factories (VFs). More recently, these VFs were shown to be liquid-like, sharing properties with membrane-less organelles driven by liquid–liquid phase separation (LLPS) in a process widely referred to as biomolecular condensation. Some of the best described examples of these structures come from negative stranded RNA viruses, where micrometer size VFs are formed toward the end of the infectious cycle. We here discuss some basic principles of LLPS in connection with several examples of VFs and propose a view, which integrates viral replication mechanisms with the biochemistry underlying liquid-like organelles. In this view, viral protein and RNA components gradually accumulate up to a critical point during infection where phase separation is triggered. This yields an increase in transcription that leads in turn to increased translation and a consequent growth of initially formed condensates. According to chemical principles behind phase separation, an increase in the concentration of components increases the size of the condensate. A positive feedback cycle would thus generate in which crucial components, in particular nucleoproteins and viral polymerases, reach their highest levels required for genome replication. Progress in understanding viral biomolecular condensation leads to exploration of novel therapeutics. Furthermore, it provides insights into the fundamentals of phase separation in the regulation of cellular gene function given that virus replication and transcription, in particular those requiring host polymerases, are governed by the same biochemical principles.
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23
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Spegg V, Altmeyer M. Biomolecular condensates at sites of DNA damage: More than just a phase. DNA Repair (Amst) 2021; 106:103179. [PMID: 34311273 PMCID: PMC7612016 DOI: 10.1016/j.dnarep.2021.103179] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 12/12/2022]
Abstract
Protein recruitment to DNA break sites is an integral part of the DNA damage response (DDR). Elucidation of the hierarchy and temporal order with which DNA damage sensors as well as repair and signaling factors assemble around chromosome breaks has painted a complex picture of tightly regulated macromolecular interactions that build specialized compartments to facilitate repair and maintenance of genome integrity. While many of the underlying interactions, e.g. between repair factors and damage-induced histone marks, can be explained by lock-and-key or induced fit binding models assuming fixed stoichiometries, structurally less well defined interactions, such as the highly dynamic multivalent interactions implicated in phase separation, also participate in the formation of multi-protein assemblies in response to genotoxic stress. Although much remains to be learned about these types of cooperative and highly dynamic interactions and their functional roles, the rapidly growing interest in material properties of biomolecular condensates and in concepts from polymer chemistry and soft matter physics to understand biological processes at different scales holds great promises. Here, we discuss nuclear condensates in the context of genome integrity maintenance, highlighting the cooperative potential between clustered stoichiometric binding and phase separation. Rather than viewing them as opposing scenarios, their combined effects can balance structural specificity with favorable physicochemical properties relevant for the regulation and function of multilayered nuclear condensates.
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Affiliation(s)
- Vincent Spegg
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Matthias Altmeyer
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland.
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24
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Hidalgo P, Pimentel A, Mojica-Santamaría D, von Stromberg K, Hofmann-Sieber H, Lona-Arrona C, Dobner T, González RA. Evidence That the Adenovirus Single-Stranded DNA Binding Protein Mediates the Assembly of Biomolecular Condensates to Form Viral Replication Compartments. Viruses 2021; 13:1778. [PMID: 34578359 PMCID: PMC8473285 DOI: 10.3390/v13091778] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/28/2021] [Accepted: 09/01/2021] [Indexed: 12/14/2022] Open
Abstract
A common viral replication strategy is characterized by the assembly of intracellular compartments that concentrate factors needed for viral replication and simultaneously conceal the viral genome from host-defense mechanisms. Recently, various membrane-less virus-induced compartments and cellular organelles have been shown to represent biomolecular condensates (BMCs) that assemble through liquid-liquid phase separation (LLPS). In the present work, we analyze biophysical properties of intranuclear replication compartments (RCs) induced during human adenovirus (HAdV) infection. The viral ssDNA-binding protein (DBP) is a major component of RCs that contains intrinsically disordered and low complexity proline-rich regions, features shared with proteins that drive phase transitions. Using fluorescence recovery after photobleaching (FRAP) and time-lapse studies in living HAdV-infected cells, we show that DBP-positive RCs display properties of liquid BMCs, which can fuse and divide, and eventually form an intranuclear mesh with less fluid-like features. Moreover, the transient expression of DBP recapitulates the assembly and liquid-like properties of RCs in HAdV-infected cells. These results are of relevance as they indicate that DBP may be a scaffold protein for the assembly of HAdV-RCs and should contribute to future studies on the role of BMCs in virus-host cell interactions.
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Affiliation(s)
- Paloma Hidalgo
- Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca 62209, Mexico
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany
| | - Arturo Pimentel
- Laboratorio Nacional de Microscopía Avanzada (LNMA), Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Mexico
| | - Diana Mojica-Santamaría
- Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca 62209, Mexico
| | | | | | - Christian Lona-Arrona
- Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca 62209, Mexico
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, Mexico
| | - Thomas Dobner
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany
| | - Ramón A González
- Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca 62209, Mexico
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