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Herold K, Ruffin A, Chmura JC, Dellomo AJ, Ehrlich ES. Kaposi's sarcoma herpesvirus viral FLICE inhibitory protein modulates A20 deubiquitinase activity. Access Microbiol 2024; 6:000625.v4. [PMID: 38868372 PMCID: PMC11165616 DOI: 10.1099/acmi.0.000625.v4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 03/19/2024] [Indexed: 06/14/2024] Open
Abstract
KSHV viral FLICE inhibitory protein (vFLIP) is a potent activator of NF-κB signalling and an inhibitor of apoptosis and autophagy. Inhibition of vFLIP function and NF-κB signalling promotes lytic reactivation. Here we provide evidence for a novel function of vFLIP through inhibition of the deubiquitinating (DUB) activity of the negative regulator, A20. We demonstrate direct interaction of vFLIP with Itch and A20 and provide evidence for subsequent loss of A20 DUB activity. Our results provide further insight into the function of vFLIP in the regulation of NF-κB signalling.
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Affiliation(s)
- Kevin Herold
- Department of Biological Sciences, Towson University, Towson, MD, USA
| | - Ayana Ruffin
- Department of Biological Sciences, Towson University, Towson, MD, USA
- Cancer Reserach Institute, Emory University, Atlanta, GA, USA
| | | | - Anna J. Dellomo
- Department of Biological Sciences, Towson University, Towson, MD, USA
| | - Elana S. Ehrlich
- Department of Biological Sciences, Towson University, Towson, MD, USA
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2
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Han C, Gui C, Dong S, Lan K. The Interplay between KSHV Infection and DNA-Sensing Pathways. Viruses 2024; 16:749. [PMID: 38793630 PMCID: PMC11125855 DOI: 10.3390/v16050749] [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: 04/19/2024] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/26/2024] Open
Abstract
During viral infection, the innate immune system utilizes a variety of specific intracellular sensors to detect virus-derived nucleic acids and activate a series of cellular signaling cascades that produce type I IFNs and proinflammatory cytokines and chemokines. Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic double-stranded DNA virus that has been associated with a variety of human malignancies, including Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman disease. Infection with KSHV activates various DNA sensors, including cGAS, STING, IFI16, and DExD/H-box helicases. Activation of these DNA sensors induces the innate immune response to antagonize the virus. To counteract this, KSHV has developed countless strategies to evade or inhibit DNA sensing and facilitate its own infection. This review summarizes the major DNA-triggered sensing signaling pathways and details the current knowledge of DNA-sensing mechanisms involved in KSHV infection, as well as how KSHV evades antiviral signaling pathways to successfully establish latent infection and undergo lytic reactivation.
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Affiliation(s)
- Chunyan Han
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430062, China
| | - Chenwu Gui
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430062, China
| | - Shuhong Dong
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430062, China
| | - Ke Lan
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430062, China
- Department of Infectious Diseases, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan 430071, China
- Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan 430072, China
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Ren P, Niu D, Chang S, Yu L, Ren J, Ma Y, Lan K. RUNX3 inhibits KSHV lytic replication by binding to the viral genome and repressing transcription. J Virol 2024; 98:e0156723. [PMID: 38197631 PMCID: PMC10878072 DOI: 10.1128/jvi.01567-23] [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: 10/07/2023] [Accepted: 12/11/2023] [Indexed: 01/11/2024] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) belongs to the gamma herpesvirus family, which can cause human malignancies including Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman's diseases. KSHV typically maintains a persistent latent infection within the host. However, after exposure to intracellular or extracellular stimuli, KSHV lytic replication can be reactivated. The reactivation process of KSHV triggers the innate immune response to limit viral replication. Here, we found that the transcriptional regulator RUNX3 is transcriptionally upregulated by the NF-κB signaling pathway in KSHV-infected SLK cells and B cells during KSHV reactivation. Notably, knockdown of RUNX3 significantly promotes viral lytic replication as well as the gene transcription of KSHV. Consistent with this finding, overexpression of RUNX3 impairs viral lytic replication. Mechanistically, RUNX3 binds to the KSHV genome and limits viral replication through transcriptional repression, which is related to its DNA- and ATP-binding ability. However, KSHV has also evolved corresponding strategies to antagonize this inhibition by using the viral protein RTA to target RUNX3 for ubiquitination and proteasomal degradation. Altogether, our study suggests that RUNX3, a novel host-restriction factor of KSHV that represses the transcription of viral genes, may serve as a potential target to restrict KSHV transmission and disease development.IMPORTANCEThe reactivation of Kaposi's sarcoma-associated herpesvirus (KSHV) from latent infection to lytic replication is important for persistent viral infection and tumorigenicity. However, reactivation is a complex event, and the regulatory mechanisms of this process are not fully elucidated. Our study revealed that the host RUNX3 is upregulated by the NF-κB signaling pathway during KSHV reactivation, which can repress the transcription of KSHV genes. At the late stage of lytic replication, KSHV utilizes a mechanism involving RTA to degrade RUNX3, thus evading host inhibition. This finding helps elucidate the regulatory mechanism of the KSHV life cycle and may provide new clues for the development of therapeutic strategies for KSHV-associated diseases.
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Affiliation(s)
- Pengyu Ren
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Danping Niu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Sijia Chang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Lei Yu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Junrui Ren
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yuanming Ma
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Ke Lan
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
- Department of Infectious Diseases, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
- Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan, China
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4
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Pakjoo M, Ahmadi SE, Zahedi M, Jaafari N, Khademi R, Amini A, Safa M. Interplay between proteasome inhibitors and NF-κB pathway in leukemia and lymphoma: a comprehensive review on challenges ahead of proteasome inhibitors. Cell Commun Signal 2024; 22:105. [PMID: 38331801 PMCID: PMC10851565 DOI: 10.1186/s12964-023-01433-5] [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: 08/13/2023] [Accepted: 12/11/2023] [Indexed: 02/10/2024] Open
Abstract
The current scientific literature has extensively explored the potential role of proteasome inhibitors (PIs) in the NF-κB pathway of leukemia and lymphoma. The ubiquitin-proteasome system (UPS) is a critical component in regulating protein degradation in eukaryotic cells. PIs, such as BTZ, are used to target the 26S proteasome in hematologic malignancies, resulting in the prevention of the degradation of tumor suppressor proteins, the activation of intrinsic mitochondrial-dependent cell death, and the inhibition of the NF-κB signaling pathway. NF-κB is a transcription factor that plays a critical role in the regulation of apoptosis, cell proliferation, differentiation, inflammation, angiogenesis, and tumor migration. Despite the successful use of PIs in various hematologic malignancies, there are limitations such as resistant to these inhibitors. Some reports suggest that PIs can induce NF-κB activation, which increases the survival of malignant cells. This article discusses the various aspects of PIs' effects on the NF-κB pathway and their limitations. Video Abstract.
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Affiliation(s)
- Mahdi Pakjoo
- Department of Hematology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
- ATMP department, Breast cancer research center, Motamed cancer institute, ACECR, P.O. BOX:15179/64311, Tehran, Iran
| | - Seyed Esmaeil Ahmadi
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Zahedi
- Department of Medical Biotechnology, School of Allied Medicine, Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - Niloofar Jaafari
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Reyhane Khademi
- Thalassemia & Hemoglobinopathy Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Ali Amini
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Majid Safa
- Department of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran.
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Oswald J, Constantine M, Adegbuyi A, Omorogbe E, Dellomo AJ, Ehrlich ES. E3 Ubiquitin Ligases in Gammaherpesviruses and HIV: A Review of Virus Adaptation and Exploitation. Viruses 2023; 15:1935. [PMID: 37766341 PMCID: PMC10535929 DOI: 10.3390/v15091935] [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: 08/21/2023] [Revised: 09/10/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
For productive infection and replication to occur, viruses must control cellular machinery and counteract restriction factors and antiviral proteins. Viruses can accomplish this, in part, via the regulation of cellular gene expression and post-transcriptional and post-translational control. Many viruses co-opt and counteract cellular processes via modulation of the host post-translational modification machinery and encoding or hijacking kinases, SUMO ligases, deubiquitinases, and ubiquitin ligases, in addition to other modifiers. In this review, we focus on three oncoviruses, Epstein-Barr virus (EBV), Kaposi's sarcoma herpesvirus (KSHV), and human immunodeficiency virus (HIV) and their interactions with the ubiquitin-proteasome system via viral-encoded or cellular E3 ubiquitin ligase activity.
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Affiliation(s)
| | | | | | | | | | - Elana S. Ehrlich
- Department of Biological Sciences, Towson University, Towson, MD 21252, USA
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Mlera L, Collins-McMillen D, Zeltzer S, Buehler JC, Moy M, Zarrella K, Caviness K, Cicchini L, Tafoya DJ, Goodrum F. Liver X Receptor-Inducible Host E3 Ligase IDOL Targets a Human Cytomegalovirus Reactivation Determinant. J Virol 2023; 97:e0075823. [PMID: 37338407 PMCID: PMC10373547 DOI: 10.1128/jvi.00758-23] [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: 05/22/2023] [Accepted: 05/30/2023] [Indexed: 06/21/2023] Open
Abstract
Liver X receptor (LXR) signaling broadly restricts virus replication; however, the mechanisms of restriction are poorly defined. Here, we demonstrate that the cellular E3 ligase LXR-inducible degrader of low-density lipoprotein receptor (IDOL) targets the human cytomegalovirus (HMCV) UL136p33 protein for turnover. UL136 encodes multiple proteins that differentially impact latency and reactivation. UL136p33 is a determinant of reactivation. UL136p33 is targeted for rapid turnover by the proteasome, and its stabilization by mutation of lysine residues to arginine results in a failure to quiet replication for latency. We show that IDOL targets UL136p33 for turnover but not the stabilized variant. IDOL is highly expressed in undifferentiated hematopoietic cells where HCMV establishes latency but is sharply downregulated upon differentiation, a stimulus for reactivation. We hypothesize that IDOL maintains low levels of UL136p33 for the establishment of latency. Consistent with this hypothesis, knockdown of IDOL impacts viral gene expression in wild-type (WT) HCMV infection but not in infection where UL136p33 has been stabilized. Furthermore, the induction of LXR signaling restricts WT HCMV reactivation from latency but does not affect the replication of a recombinant virus expressing a stabilized variant of UL136p33. This work establishes the UL136p33-IDOL interaction as a key regulator of the bistable switch between latency and reactivation. It further suggests a model whereby a key viral determinant of HCMV reactivation is regulated by a host E3 ligase and acts as a sensor at the tipping point between the decision to maintain the latent state or exit latency for reactivation. IMPORTANCE Herpesviruses establish lifelong latent infections, which pose an important risk for disease particularly in the immunocompromised. Our work is focused on the betaherpesvirus human cytomegalovirus (HCMV) that latently infects the majority of the population worldwide. Defining the mechanisms by which HCMV establishes latency or reactivates from latency is important for controlling viral disease. Here, we demonstrate that the cellular inducible degrader of low-density lipoprotein receptor (IDOL) targets a HCMV determinant of reactivation for degradation. The instability of this determinant is important for the establishment of latency. This work defines a pivotal virus-host interaction that allows HCMV to sense changes in host biology to navigate decisions to establish latency or to replicate.
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Affiliation(s)
- Luwanika Mlera
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
- BIO5 Institute, University of Arizona, Tucson, Arizona, USA
| | - Donna Collins-McMillen
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
- BIO5 Institute, University of Arizona, Tucson, Arizona, USA
| | - Sebastian Zeltzer
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
- BIO5 Institute, University of Arizona, Tucson, Arizona, USA
| | - Jason C. Buehler
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
- BIO5 Institute, University of Arizona, Tucson, Arizona, USA
| | - Melissa Moy
- Graduate Interdisciplinary Program in Cancer Biology, University of Arizona, Tucson, Arizona, USA
| | - Kristen Zarrella
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
| | - Katie Caviness
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
- BIO5 Institute, University of Arizona, Tucson, Arizona, USA
- Graduate Interdisciplinary Program in Genetics, University of Arizona, Tucson, Arizona, USA
| | - Louis Cicchini
- BIO5 Institute, University of Arizona, Tucson, Arizona, USA
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA
| | - David J. Tafoya
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
- BIO5 Institute, University of Arizona, Tucson, Arizona, USA
| | - Felicia Goodrum
- Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
- BIO5 Institute, University of Arizona, Tucson, Arizona, USA
- Graduate Interdisciplinary Program in Cancer Biology, University of Arizona, Tucson, Arizona, USA
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA
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Combs LR, Combs J, McKenna R, Toth Z. Protein Degradation by Gammaherpesvirus RTAs: More Than Just Viral Transactivators. Viruses 2023; 15:730. [PMID: 36992439 PMCID: PMC10055789 DOI: 10.3390/v15030730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/09/2023] [Accepted: 03/10/2023] [Indexed: 03/18/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is a member of the Gammaherpesvirus subfamily that encodes several viral proteins with intrinsic E3 ubiquitin ligase activity or the ability to hijack host E3 ubiquitin ligases to modulate the host's immune response and to support the viral life cycle. This review focuses specifically on how the immediate-early KSHV protein RTA (replication and transcription activator) hijacks the host's ubiquitin-proteasome pathway (UPP) to target cellular and viral factors for protein degradation to allow for robust lytic reactivation. Notably, RTA's targets are either potent transcription repressors or they are activators of the innate and adaptive immune response, which block the lytic cycle of the virus. This review mainly focuses on what is currently known about the role of the E3 ubiquitin ligase activity of KSHV RTA in the regulation of the KSHV life cycle, but we will also discuss the potential role of other gammaherpesviral RTA homologs in UPP-mediated protein degradation.
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Affiliation(s)
- Lauren R. Combs
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL 32610, USA
| | - Jacob Combs
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, 1200 Newell Drive, Gainesville, FL 32610, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, 1200 Newell Drive, Gainesville, FL 32610, USA
| | - Zsolt Toth
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL 32610, USA
- UF Genetics Institute, Gainesville, FL 32610, USA
- UF Health Cancer Center, Gainesville, FL 32610, USA
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Nesterova IV, Khalturina EO, Nelubin VN, Khaidukov SV, Chudilova GA. Evaluation of the effects in the <i>in vitro</i> system of synthetic thymic hexapeptide on the expression levels of NF-κB, IFNα/βR and CD119 neutrophilic granulocytes in patients with chronic herpes viral co-infections. RUSSIAN JOURNAL OF INFECTION AND IMMUNITY 2022. [DOI: 10.15789/2220-7619-eot-1928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Background. Strategies used by herpes viruses with human cells are complex and multifaceted. On one hand, inborn defects in antiviral immune defense have been unveiled, which also affect interferon (IFN) system underlying development of chronic recalcitrant relapsing viral infections such as remittent respiratory viral infections, herpesvirus infections, and papillomavirus infections. On the other hand, numerous viruses are able to damage both immune system and IFN network. During inborn and acquired defects in IFN network, inborn or induced mutation in gene products involved in signaling cascades aimed at upregulating gene expression responsible for IFN production are observed. One of the strategies used by diverse viruses is altering some signaling pathways resulting in activated transcription factors including nuclear factor NF-kB. However, antiviral mechanisms executed by neutrophilic granulocytes (NGs), particularly affecting NF-kB expression have not been elucidated. Aim of the study: to study in vitro features of NF-kB expression and number of neutrophilic granulocytes (NG) expressing membrane IFN/R and IFNR in patients with atypical chronic active herpes virus infections (AChA-HVI), followed by assessing an effect of arginyl-alpha-aspartyl-lysyl-valyl-tyrosyl-arginine hexapeptide (HP), a synthetic analogue of the active center of the thymopoietin (active substance of drug Imunofan, Russia), on the expression of NG NF-kB and IFN/R and IFNR. Materials and methods. We observed 25 patients of both sexes aged 23 to 64 years with AChA-HVI, manifested by chronic fatigue syndrome and cognitive disorders. Study design: stage 1 clinical, ELISA, PCR methods, FC was used. Stage 2 the in vitro experiment: 32 blood samples from 8 healthy adults and 375 blood samples from 25 patients with AChA-HVI were analyzed: % NG expressing NF-kB, IFN/R, IFNR and the relevant MFI levels by using FC before and after incubation with HP. Results. Our study demonstrated low level (MFI) of NF-kB expression in 100% NG associated with decreased % of NG expressing IFN/R and IFNR in all patients with AChA-HVI and low serum level for IFN and IFN in comparison with healthy individuals. In the in vitro experiment there was shown that 100% of NG expressed NF-kB after exposure to HP. However, only 48% patients (SG 2) restored NF-kB expression level (MFI) to normal range and 52% of cases (SG 1) had no response. HP increased % of NG expressing IFN/R in SG 2 and increased % of NG expressing IFNR in SG 1. Conclusions. It was shown, that influence of HP in vitro has ambiguous effects on the expression of NF-kB, % of NG expressing IFN/R and IFNR in patients with AChA-HVI. We assume that different NF-kB response to HP is associated with inborn or secondary NF-kB deficiency.
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Mohanty S, Kumar A, Das P, Sahu SK, Mukherjee R, Ramachandranpillai R, Nair SS, Choudhuri T. Nm23-H1 induces apoptosis in primary effusion lymphoma cells via inhibition of NF-κB signaling through interaction with oncogenic latent protein vFLIP K13 of Kaposi’s sarcoma-associated herpes virus. Cell Oncol (Dordr) 2022; 45:967-989. [DOI: 10.1007/s13402-022-00701-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2022] [Indexed: 11/03/2022] Open
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KSHV RTA antagonizes SMC5/6 complex-induced viral chromatin compaction by hijacking the ubiquitin-proteasome system. PLoS Pathog 2022; 18:e1010744. [PMID: 35914008 PMCID: PMC9371351 DOI: 10.1371/journal.ppat.1010744] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 08/11/2022] [Accepted: 07/15/2022] [Indexed: 02/07/2023] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) is a double-stranded DNA virus with the capacity to establish life-long latent infection. During latent infection, the viral genome persists as a circular episome that associates with cellular histones and exists as a nonintegrated minichromosome in the nucleus of infected cells. Chromatin structure and epigenetic programming are required for the proper control of viral gene expression and stable maintenance of viral DNA. However, there is still limited knowledge regarding how the host regulates the chromatin structure and maintenance of episomal DNA. Here, we found that the cellular protein structural maintenance of chromosome (SMC) complex SMC5/6 recognizes and associates with the KSHV genome to inhibit its replication. The SMC5/6 complex can bind to the KSHV genome and suppress KSHV gene transcription by condensing the viral chromatin and creating a repressive chromatin structure. Correspondingly, KSHV employs an antagonistic strategy by utilizing the viral protein RTA to degrade the SMC5/6 complex and antagonize the inhibitory effect of this complex on viral gene transcription. Interestingly, this antagonistic mechanism of RTA is evolutionarily conserved among γ-herpesviruses. Our work suggests that the SMC5/6 complex is a new host factor that restricts KSHV replication. KSHV can establish life-long latent infection. During latency, the viral genome is maintained as an extrachromosomal episome in the infected cells. We demonstrated that the host protein SMC5/6 complex associates with the KSHV genome and results in direct transcriptional inhibition by creating a transcriptionally repressive chromatin structure of the viral genome. RTA, the master switch protein of KSHV, can hijack the ubiquitin-proteasome system to degrade the SMC5/6 complex to antagonize its inhibitory effect on viral gene transcription. Interestingly, this function of RTA is evolutionarily conserved among γ-herpesviruses.
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11
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The interplay between EBV and KSHV viral products and NF-κB pathway in oncogenesis. Infect Agent Cancer 2020; 15:62. [PMID: 33072180 PMCID: PMC7559203 DOI: 10.1186/s13027-020-00317-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 07/29/2020] [Indexed: 02/08/2023] Open
Abstract
Among the DNA tumor viruses Epstein-Barr virus (EBV) and Kaposi sarcoma herpesvirus (KSHV), account for a considerable percentage of virus-associated cancers. Deregulation of transcription factors signaling pathways is one of the most significant oncogenic characteristics of EBV and KSHV. NF-κB is a transcription factor that play a remarkable role in oncogenesis because of its function as a master regulator of a spectrum of genes involved in physiological and pathophysiological process. Constitutive activation of NF-κB is a frequent and well-described event in many human malignancies. Compelling evidence represent EBV and KSHV are capable of targeting different components of NF-κB cascade. Here, we summarized recent findings to clarify the precise relationship between dysregulation of NF-κB and EBV and KSHV-related malignancies. This essay also emphasizes on contribution of various viral products in developing cancer through alteration of NF-κB signaling pathway.
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12
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Regulation of KSHV Latency and Lytic Reactivation. Viruses 2020; 12:v12091034. [PMID: 32957532 PMCID: PMC7551196 DOI: 10.3390/v12091034] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/10/2020] [Accepted: 09/12/2020] [Indexed: 02/06/2023] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with three malignancies— Kaposi’s sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman’s disease (MCD). Central to the pathogenesis of these diseases is the KSHV viral life cycle, which is composed of a quiescent latent phase and a replicative lytic phase. While the establishment of latency enables persistent KSHV infection and evasion of the host immune system, lytic replication is essential for the dissemination of the virus between hosts and within the host itself. The transition between these phases, known as lytic reactivation, is controlled by a complex set of environmental, host, and viral factors. The effects of these various factors converge on the regulation of two KSHV proteins whose functions facilitate each phase of the viral life cycle—latency-associated nuclear antigen (LANA) and the master switch of KSHV reactivation, replication and transcription activator (RTA). This review presents the current understanding of how the transition between the phases of the KSHV life cycle is regulated, how the various phases contribute to KSHV pathogenesis, and how the viral life cycle can be exploited as a therapeutic target.
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13
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Bojagora A, Saridakis V. USP7 manipulation by viral proteins. Virus Res 2020; 286:198076. [DOI: 10.1016/j.virusres.2020.198076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 05/14/2020] [Accepted: 06/24/2020] [Indexed: 01/27/2023]
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14
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Association of NFκB and related-cytokines with the viral load and development of antibodies against HHV-8 in people living with HIV/AIDS. Med Microbiol Immunol 2019; 209:41-49. [PMID: 31586222 DOI: 10.1007/s00430-019-00637-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 09/23/2019] [Indexed: 02/08/2023]
Abstract
Human gammaherpesvirus 8 (HHV-8) replication is influenced by a complex interaction between viral and host elements. Here, we evaluated the expression of NFκB and TNF-α in B (CD19 +) and T (CD3 +) lymphocytes, and the serum concentration of IL-1β and IL-12 cytokines in people living with HIV/AIDS (PLHA), negative for HHV-8-related diseases, and who presented antibodies to latent or lytic antigens from HHV-8. In addition, we also evaluated the correlation of HHV-8 viral load with NFκB, TNF-α, IL-1β and IL-12 levels. The expression of NFκB (p < 0.0001) or TNF-α (p < 0.0001) in B lymphocytes (CD19 +) and the IL-1β (p < 0.0266) and IL-12 (p < 0.0001) concentrations were associated with the presence of antibodies to HHV-8 lytic antigens. The CD19 + NFκB + TNF-α + and CD3 + NFκB + TNF-α + cells were also associated with the presence of antibodies to lytic infection (p < 0.0001). Among all PLHA evaluated, only individuals with the highest titers of lytic antibodies, i.e., 1:320, had detectable HHV-8 viral load. In these, HHV-8 viral load was correlated to NFκB (r = 0.6, p = 0.003) and TNF-α (r = 0.5, p = 0.01) (both in CD19 + lymphocytes) and with IL-1β (r = 0.5, p = 0.01) and IL-12 (r = 0.6, p = 0.006) levels. We believe that viral replication and/or reactivation, in addition to being associated with the development of lytic antibodies against HHV-8, may be associated with inflammatory response via NFκB. Finally, although immune response imbalance has been previously related to HHV-8-associated diseases, our results indicate that important changes in immunity, mainly in the inflammatory response, may be clearly observed in individuals with HHV-8, but who have not yet presented clinical manifestations.
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15
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Gonçales JP, Silva Júnior JVJ, Lopes TRR, Tozetto-Mendoza TR, de Farias Guimarães D, de Morais VMS, Coêlho MRCD. Association of polymorphisms in NFκB1 promoter and NFκBIA gene with the development of antibodies against HHV-8 in HIV-infected individuals. Virology 2019; 535:255-260. [PMID: 31344550 DOI: 10.1016/j.virol.2019.07.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 07/03/2019] [Accepted: 07/09/2019] [Indexed: 01/01/2023]
Abstract
Human gammaherpesvirus 8 (HHV-8) is the etiologic agent of Kaposi's sarcoma, multicentric Castleman's disease and primary effusion lymphoma. Like other herpesviruses, the HHV-8 may exhibit latent or lytic cycle, both regulated by viral and host factors. Regarding host factors, we analysed the association of polymorphisms in NFkB1 promoter (NFkB1-94 ins/del ATTG) and NFκBIA gene (NFκBIA 3'UTR A→G) with the development of antibodies against latent or lytic antigens from HHV-8. The ins/del [OR 7.9 (95% CI 3.3-19.1), p < 0.001], AG [OR 12.3 (95% CI 4.3-34.9) p < 0.001], GG [OR 9.4 (95% CI 3.2-27.9), p < 0.001], ins/del + AG [OR 94.5 (95% CI 9.6-924.4), <0.0001], ins/del + GG [OR 50.4 (95% CI 5.2-482.2, p < 0.0001] and G allele [OR 3.3 (95% CI 2.0-5.6), p < 0.001] were strongly related with the presence of antibodies to lytic antigens. This is the first association of polymorphisms in NFκB1 promoter and NFκBIA gene with the development of antibodies against HHV-8.
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Affiliation(s)
- Juliana Prado Gonçales
- Virology Sector, Laboratory of Immunopathology Keizo Asami, Federal University of Pernambuco, Pernambuco, Brazil
| | - José Valter Joaquim Silva Júnior
- Virology Sector, Department of Preventive Veterinary Medicine, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Thaísa Regina Rocha Lopes
- Virology Sector, Laboratory of Immunopathology Keizo Asami, Federal University of Pernambuco, Pernambuco, Brazil
| | | | | | | | - Maria Rosangela Cunha Duarte Coêlho
- Virology Sector, Laboratory of Immunopathology Keizo Asami, Federal University of Pernambuco, Pernambuco, Brazil; Department of Physiology and Pharmacology, Center of Biosciences, Federal University of Pernambuco, Pernambuco, Brazil.
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16
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He M, Cheng F, da Silva SR, Tan B, Sorel O, Gruffaz M, Li T, Gao SJ. Molecular Biology of KSHV in Relation to HIV/AIDS-Associated Oncogenesis. Cancer Treat Res 2019; 177:23-62. [PMID: 30523620 DOI: 10.1007/978-3-030-03502-0_2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Discovered in 1994, Kaposi's sarcoma-associated herpesvirus (KSHV) has been associated with four human malignancies including Kaposi's sarcoma, primary effusion lymphoma, a subset of multicentric Castleman's disease, and KSHV inflammatory cytokine syndrome. These malignancies mostly occur in immunocompromised patients including patients with acquired immunodeficiency syndrome and often cause significant mortality because of the lack of effective therapies. Significant progresses have been made to understand the molecular basis of KSHV infection and KSHV-induced oncogenesis in the last two decades. This chapter provides an update on the recent advancements focusing on the molecular events of KSHV primary infection, the mechanisms regulating KSHV life cycle, innate and adaptive immunity, mechanism of KSHV-induced tumorigenesis and inflammation, and metabolic reprogramming in KSHV infection and KSHV-transformed cells.
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Affiliation(s)
- Meilan He
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, USA
| | - Fan Cheng
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, USA
| | - Suzane Ramos da Silva
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, USA
| | - Brandon Tan
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, USA
| | - Océane Sorel
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, USA
| | - Marion Gruffaz
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, USA
| | - Tingting Li
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, USA
| | - Shou-Jiang Gao
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, USA.
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17
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Latent infection with Kaposi's sarcoma-associated herpesvirus enhances retrotransposition of long interspersed element-1. Oncogene 2019; 38:4340-4351. [PMID: 30770900 DOI: 10.1038/s41388-019-0726-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 01/18/2019] [Indexed: 12/14/2022]
Abstract
Kaposi's sarcoma (KS)-associated herpesvirus (KSHV), a gamma-2 herpesvirus, is the causative agent of KS, primary effusion lymphoma (PEL), and a plasma cell variant of multicentric Castleman's disease. Although KSHV latency is detected in KS-related tumors, oncogenic pathways activated by KSHV latent infection are not fully understood. Here, we found that retrotransposition of long interspersed element-1 (L1), a retrotransposon in the human genome, was enhanced in PEL cells. Among the KSHV latent genes, viral FLICE-inhibitory protein (vFLIP) enhanced L1 retrotransposition in an NF-κB-dependent manner. Intracellular cell adhesion molecule-1 (ICAM-1), an NF-κB target, regulated the vFLIP-mediated enhancement of L1 retrotransposition. Furthermore, ICAM-1 downregulated the expression of Moloney leukemia virus 10 (MOV10), an L1 restriction factor. Knockdown of ICAM-1 or overexpression of MOV10 relieved the vFLIP-mediated enhancement of L1 retrotransposition. Collectively, during KSHV latency, vFLIP upregulates ICAM-1 in an NF-κB-dependent manner, which, in turn, downregulates MOV10 expression and thereby enhances L1 retrotransposition. Because active L1 retrotransposition can lead to genomic instability, which is commonly found in KS and PEL, activation of L1 retrotransposition during KSHV latency may accelerate oncogenic processes through enhancing genomic instability. Our results suggest that L1 retrotransposition may be a novel target for impeding tumor development in KSHV-infected patients.
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Choi YB, Choi Y, Harhaj EW. Peroxisomes support human herpesvirus 8 latency by stabilizing the viral oncogenic protein vFLIP via the MAVS-TRAF complex. PLoS Pathog 2018; 14:e1007058. [PMID: 29746593 PMCID: PMC5963799 DOI: 10.1371/journal.ppat.1007058] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 05/22/2018] [Accepted: 04/25/2018] [Indexed: 12/22/2022] Open
Abstract
Human herpesvirus 8 (HHV-8) is causally related to human malignancies. HHV-8 latent viral FLICE-inhibitory protein (vFLIP) is a viral oncoprotein that is linked to pathogenesis, but how its expression is regulated is largely unknown. In an attempt to understand the role of the mitochondrial antiviral signaling (MAVS) adaptor in HHV-8 infection, we discovered that vFLIP expression was post-translationally up-regulated by the MAVS signaling complex on peroxisomes. Furthermore, we demonstrated that vFLIP could be targeted to the peroxisomes, where it was oncogenically active, in a PEX19-dependent manner. Targeted disruption of vFLIP and MAVS interaction resulted in a decrease in vFLIP expression and selectively promoted death of latently HHV-8-infected cells, providing therapeutic potential for treating HHV-8 diseases. Collectively, our experimental results suggest novel involvement of peroxisomes and MAVS in the stabilization of vFLIP and thereby in the establishment or maintenance of HHV-8 latency and associated pathogenesis.
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Affiliation(s)
- Young Bong Choi
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
| | - Yeeun Choi
- Centennial High School, Ellicott City, Maryland, United States of America
| | - Edward William Harhaj
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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19
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KSHV and the Role of Notch Receptor Dysregulation in Disease Progression. Pathogens 2017; 6:pathogens6030034. [PMID: 28777778 PMCID: PMC5617991 DOI: 10.3390/pathogens6030034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/17/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of two human cancers, Kaposi's Sarcoma (KS) and primary effusion lymphoma (PEL), and a lymphoproliferation, Multicentric Castleman's Disease (MCD). Progression to tumor development in KS is dependent upon the reactivation of the virus from its latent state. We, and others, have shown that the Replication and transcriptional activator (Rta) protein is the only viral gene product that is necessary and sufficient for viral reactivation. To induce the reactivation and transcription of viral genes, Rta forms a complex with the cellular DNA binding component of the canonical Notch signaling pathway, recombination signal binding protein for Jk (RBP-Jk). Formation of this Rta:RBP-Jk complex is necessary for viral reactivation to occur. Expression of activated Notch has been shown to be dysregulated in KSHV infected cells and to be necessary for cell growth and disease progression. Studies into the involvement of activated Notch in viral reactivation have yielded varied results. In this paper, we review the current literature regarding Notch dysregulation by KSHV and its role in viral infection and cellular pathogenesis.
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21
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Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen: Replicating and Shielding Viral DNA during Viral Persistence. J Virol 2017; 91:JVI.01083-16. [PMID: 28446671 DOI: 10.1128/jvi.01083-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Kaposi's sarcoma herpesvirus (KSHV) establishes lifelong latency. The viral latency-associated nuclear antigen (LANA) promotes viral persistence by tethering the viral genome to cellular chromosomes and by participating in latent DNA replication. Recently, the structure of the LANA C-terminal DNA binding domain was solved and new cytoplasmic variants of LANA were discovered. We discuss how these findings contribute to our current view of LANA structure and assembly and of its role during viral persistence.
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22
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Aneja KK, Yuan Y. Reactivation and Lytic Replication of Kaposi's Sarcoma-Associated Herpesvirus: An Update. Front Microbiol 2017; 8:613. [PMID: 28473805 PMCID: PMC5397509 DOI: 10.3389/fmicb.2017.00613] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/27/2017] [Indexed: 12/30/2022] Open
Abstract
The life cycle of Kaposi’s sarcoma-associated herpesvirus (KSHV) consists of two phases, latent and lytic. The virus establishes latency as a strategy for avoiding host immune surveillance and fusing symbiotically with the host for lifetime persistent infection. However, latency can be disrupted and KSHV is reactivated for entry into the lytic replication. Viral lytic replication is crucial for efficient dissemination from its long-term reservoir to the sites of disease and for the spread of the virus to new hosts. The balance of these two phases in the KSHV life cycle is important for both the virus and the host and control of the switch between these two phases is extremely complex. Various environmental factors such as oxidative stress, hypoxia, and certain chemicals have been shown to switch KSHV from latency to lytic reactivation. Immunosuppression, unbalanced inflammatory cytokines, and other viral co-infections also lead to the reactivation of KSHV. This review article summarizes the current understanding of the initiation and regulation of KSHV reactivation and the mechanisms underlying the process of viral lytic replication. In particular, the central role of an immediate-early gene product RTA in KSHV reactivation has been extensively investigated. These studies revealed multiple layers of regulation in activation of RTA as well as the multifunctional roles of RTA in the lytic replication cascade. Epigenetic regulation is known as a critical layer of control for the switch of KSHV between latency and lytic replication. The viral non-coding RNA, PAN, was demonstrated to play a central role in the epigenetic regulation by serving as a guide RNA that brought chromatin remodeling enzymes to the promoters of RTA and other lytic genes. In addition, a novel dimension of regulation by microPeptides emerged and has been shown to regulate RTA expression at the protein level. Overall, extensive investigation of KSHV reactivation and lytic replication has revealed a sophisticated regulation network that controls the important events in KSHV life cycle.
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Affiliation(s)
- Kawalpreet K Aneja
- Department of Microbiology, University of Pennsylvania School of Dental Medicine, PhiladelphiaPA, USA
| | - Yan Yuan
- Department of Microbiology, University of Pennsylvania School of Dental Medicine, PhiladelphiaPA, USA
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23
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Mariggiò G, Koch S, Zhang G, Weidner-Glunde M, Rückert J, Kati S, Santag S, Schulz TF. Kaposi Sarcoma Herpesvirus (KSHV) Latency-Associated Nuclear Antigen (LANA) recruits components of the MRN (Mre11-Rad50-NBS1) repair complex to modulate an innate immune signaling pathway and viral latency. PLoS Pathog 2017; 13:e1006335. [PMID: 28430817 PMCID: PMC5415203 DOI: 10.1371/journal.ppat.1006335] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 05/03/2017] [Accepted: 04/05/2017] [Indexed: 12/31/2022] Open
Abstract
Kaposi Sarcoma Herpesvirus (KSHV), a γ2-herpesvirus and class 1 carcinogen, is responsible for at least three human malignancies: Kaposi Sarcoma (KS), Primary Effusion Lymphoma (PEL) and Multicentric Castleman's Disease (MCD). Its major nuclear latency protein, LANA, is indispensable for the maintenance and replication of latent viral DNA in infected cells. Although LANA is mainly a nuclear protein, cytoplasmic isoforms of LANA exist and can act as antagonists of the cytoplasmic DNA sensor, cGAS. Here, we show that cytosolic LANA also recruits members of the MRN (Mre11-Rad50-NBS1) repair complex in the cytosol and thereby inhibits their recently reported role in the sensing of cytoplasmic DNA and activation of the NF-κB pathway. Inhibition of NF-κB activation by cytoplasmic LANA is accompanied by increased lytic replication in KSHV-infected cells, suggesting that MRN-dependent NF-κB activation contributes to KSHV latency. Cytoplasmic LANA may therefore support the activation of KSHV lytic replication in part by counteracting the activation of NF-κB in response to cytoplasmic DNA. This would complement the recently described role of cytoplasmic LANA in blocking an interferon response triggered by cGAS and thereby promoting lytic reactivation. Our findings highlight a second point at which cytoplasmic LANA interferes with the innate immune response, as well as the importance of the recently discovered role of cytoplasmic MRN complex members as innate sensors of cytoplasmic DNA for the control of KSHV replication.
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MESH Headings
- Acid Anhydride Hydrolases
- Antigens, Viral/genetics
- Antigens, Viral/immunology
- Antigens, Viral/metabolism
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Cytoplasm/metabolism
- DNA Repair Enzymes/genetics
- DNA Repair Enzymes/metabolism
- DNA Replication
- DNA, Viral/genetics
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- HEK293 Cells
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/immunology
- Herpesvirus 8, Human/physiology
- Humans
- Immunity, Innate
- MRE11 Homologue Protein
- Models, Biological
- NF-kappa B/genetics
- NF-kappa B/metabolism
- Nuclear Proteins/genetics
- Nuclear Proteins/immunology
- Nuclear Proteins/metabolism
- Protein Isoforms
- Sarcoma, Kaposi/immunology
- Sarcoma, Kaposi/virology
- Signal Transduction
- Virus Latency
- Virus Replication
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Affiliation(s)
- Giuseppe Mariggiò
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Sandra Koch
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Guigen Zhang
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Magdalena Weidner-Glunde
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Jessica Rückert
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Semra Kati
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Susann Santag
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
| | - Thomas F. Schulz
- Institute of Virology, Hannover Medical School, Hannover, Germany
- German Centre for Infection Research, Hannover-Braunschweig Site, Germany
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24
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Hamidzadeh K, Christensen SM, Dalby E, Chandrasekaran P, Mosser DM. Macrophages and the Recovery from Acute and Chronic Inflammation. Annu Rev Physiol 2017; 79:567-592. [PMID: 27959619 PMCID: PMC5912892 DOI: 10.1146/annurev-physiol-022516-034348] [Citation(s) in RCA: 230] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In recent years, researchers have devoted much attention to the diverse roles of macrophages and their contributions to tissue development, wound healing, and angiogenesis. What should not be lost in the discussions regarding the diverse biology of these cells is that when perturbed, macrophages are the primary contributors to potentially pathological inflammatory processes. Macrophages stand poised to rapidly produce large amounts of inflammatory cytokines in response to danger signals. The production of these cytokines can initiate a cascade of inflammatory mediator release that can lead to wholesale tissue destruction. The destructive inflammatory capability of macrophages is amplified by exposure to exogenous interferon-γ, which prolongs and heightens inflammatory responses. In simple terms, macrophages can thus be viewed as incendiary devices with hair triggers waiting to detonate. We have begun to ask questions about how these cells can be regulated to mitigate the collateral destruction associated with macrophage activation.
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Affiliation(s)
- Kajal Hamidzadeh
- Department of Cell Biology and Molecular Genetics, Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland 20742;
| | - Stephen M Christensen
- Department of Cell Biology and Molecular Genetics, Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland 20742;
| | - Elizabeth Dalby
- Department of Cell Biology and Molecular Genetics, Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland 20742;
| | - Prabha Chandrasekaran
- Department of Cell Biology and Molecular Genetics, Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland 20742;
| | - David M Mosser
- Department of Cell Biology and Molecular Genetics, Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland 20742;
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25
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Chmura JC, Herold K, Ruffin A, Atuobi T, Fabiyi Y, Mitchell AE, Choi YB, Ehrlich ES. The Itch ubiquitin ligase is required for KSHV RTA induced vFLIP degradation. Virology 2016; 501:119-126. [PMID: 27912080 DOI: 10.1016/j.virol.2016.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 10/19/2016] [Accepted: 11/23/2016] [Indexed: 01/22/2023]
Abstract
Expression of Kaposi's sarcoma herpesvirus vFLIP, a potent activator of NFkB signaling, promotes latency. Inhibition of NFkB signaling promotes lytic reactivation. We previously reported that lytic inducer, RTA, inhibits vFLIP induced NFkB signaling by inducing the degradation of vFLIP via the proteasome. Here we report that the cellular ubiquitin ligase, Itch, is required for RTA induced degradation of vFLIP. Expression of either Itch targeting shRNA or a dominant negative mutant of the ubiquitin ligase both increased the stability of vFLIP in the presence of RTA. Itch potently ubiquitinated vFLIP in vivo and in vitro. We provide evidence for interaction between RTA, vFLIP and Itch and we identified an RTA resistant mutant of vFLIP that is unable to interact with Itch. These observations contribute to our understanding of how RTA counteracts the activities of vFLIP.
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Affiliation(s)
- Jennifer C Chmura
- Department of Biological Sciences, Towson University, 8000 York Rd, Towson, MD 21252, USA
| | - Kevin Herold
- Department of Biological Sciences, Towson University, 8000 York Rd, Towson, MD 21252, USA
| | - Ayana Ruffin
- Department of Biological Sciences, Towson University, 8000 York Rd, Towson, MD 21252, USA
| | - Trudymae Atuobi
- Department of Biological Sciences, Towson University, 8000 York Rd, Towson, MD 21252, USA
| | - Yetunde Fabiyi
- Department of Biological Sciences, Towson University, 8000 York Rd, Towson, MD 21252, USA
| | - Ashley E Mitchell
- Department of Biological Sciences, Towson University, 8000 York Rd, Towson, MD 21252, USA
| | - Young Bong Choi
- Viral Oncology Program, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, 1650 Orleans Street, CRB1, Baltimore, MD 21231, USA
| | - Elana S Ehrlich
- Department of Biological Sciences, Towson University, 8000 York Rd, Towson, MD 21252, USA.
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26
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Nuclear Innate Immune DNA Sensor IFI16 Is Degraded during Lytic Reactivation of Kaposi's Sarcoma-Associated Herpesvirus (KSHV): Role of IFI16 in Maintenance of KSHV Latency. J Virol 2016; 90:8822-41. [PMID: 27466416 PMCID: PMC5021400 DOI: 10.1128/jvi.01003-16] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 07/13/2016] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED IFI16 (interferon gamma-inducible protein 16) recognizes nuclear episomal herpesvirus (Kaposi's sarcoma-associated herpesvirus [KSHV], Epstein-Barr virus [EBV], and herpes simplex virus 1 [HSV-1]) genomes and induces the inflammasome and interferon beta responses. It also acts as a lytic replication restriction factor and inhibits viral DNA replication (human cytomegalovirus [HCMV] and human papillomavirus [HPV]) and transcription (HSV-1, HCMV, and HPV) through epigenetic modifications of the viral genomes. To date, the role of IFI16 in the biology of latent viruses is not known. Here, we demonstrate that knockdown of IFI16 in the latently KSHV-infected B-lymphoma BCBL-1 and BC-3 cell lines results in lytic reactivation and increases in levels of KSHV lytic transcripts, proteins, and viral genome replication. Similar results were also observed during KSHV lytic cycle induction in TREX-BCBL-1 cells with the doxycycline-inducible lytic cycle switch replication and transcription activator (RTA) gene. Overexpression of IFI16 reduced lytic gene induction by the chemical agent 12-O-tetradecoylphorbol-13-acetate (TPA). IFI16 protein levels were significantly reduced or absent in TPA- or doxycycline-induced cells expressing lytic KSHV proteins. IFI16 is polyubiquitinated and degraded via the proteasomal pathway. The degradation of IFI16 was absent in phosphonoacetic acid-treated cells, which blocks KSHV DNA replication and, consequently, late lytic gene expression. Chromatin immunoprecipitation assays of BCBL-1 and BC-3 cells demonstrated that IFI16 binds to KSHV gene promoters. Uninfected epithelial SLK and osteosarcoma U2OS cells transfected with KSHV luciferase promoter constructs confirmed that IFI16 functions as a transcriptional repressor. These results reveal that KSHV utilizes the innate immune nuclear DNA sensor IFI16 to maintain its latency and repression of lytic transcripts, and a late lytic KSHV gene product(s) targets IFI16 for degradation during lytic reactivation. IMPORTANCE Like all herpesviruses, latency is an integral part of the life cycle of Kaposi's sarcoma-associated herpesvirus (KSHV), an etiological agent for many human cancers. Herpesviruses utilize viral and host factors to successfully evade the host immune system to maintain latency. Reactivation is a complex event where the latent episomal viral genome springs back to active transcription of lytic cycle genes. Our studies reveal that KSHV has evolved to utilize the innate immune sensor IFI16 to keep lytic cycle transcription in dormancy. We demonstrate that IFI16 binds to the lytic gene promoter, acts as a transcriptional repressor, and thereby helps to maintain latency. We also discovered that during the late stage of lytic replication, KSHV selectively degrades IFI16, thus relieving transcriptional repression. This is the first report to demonstrate the role of IFI16 in latency maintenance of a herpesvirus, and further understanding will lead to the development of strategies to eliminate latent infection.
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27
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Major Histocompatibility Complex Class II HLA-DRα Is Downregulated by Kaposi's Sarcoma-Associated Herpesvirus-Encoded Lytic Transactivator RTA and MARCH8. J Virol 2016; 90:8047-58. [PMID: 27356905 DOI: 10.1128/jvi.01079-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 06/07/2016] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED Kaposi's sarcoma-associated herpesvirus (KSHV) maintains two modes of life cycle, the latent and lytic phases. To evade the attack of the cell host's immune system, KSHV switches from the lytic to the latent phase, a phase in which only a few of viral proteins are expressed. The mechanism by which KSHV evades the attack of the immune system and establishes latency has not been fully understood. Major histocompatibility complex class II (MHC-II) molecules are key components of the immune system defense mechanism against viral infections. Here we report that HLA-DRα, a member of the MHC-II molecules, was downregulated by the replication and transcription activator (RTA) protein encoded by KSHV ORF50, an important regulator of the viral life cycle. RTA not only downregulated HLA-DRα at the protein level through direct binding and degradation through the proteasome pathway but also indirectly downregulated the protein level of HLA-DRα by enhancing the expression of MARCH8, a member of the membrane-associated RING-CH (MARCH) proteins. Our findings indicate that KSHV RTA facilitates evasion of the virus from the immune system through manipulation of HLA-DRα. IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) has a causal role in a number of human cancers, and its persistence in infected cells is controlled by the host's immune system. The mechanism by which KSHV evades an attack by the immune system has not been well understood. This work represents studies which identify a novel mechanism by which the virus can facilitate evasion of an immune system. We now show that RTA, the replication and transcription activator encoded by KSHV (ORF50), can function as an E3 ligase to degrade HLA-DRα. It can directly bind and induce degradation of HLA-DRα through the ubiquitin-proteasome degradation pathway. In addition to the direct regulation of HLA-DRα, RTA can also indirectly downregulate the level of HLA-DRα protein by upregulating transcription of MARCH8. Increased MARCH8 results in the downregulation of HLA-DRα. Furthermore, we also demonstrate that expression of HLA-DRα was impaired in KSHV de novo infection.
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Gan J, Qiao N, Strahan R, Zhu C, Liu L, Verma SC, Wei F, Cai Q. Manipulation of ubiquitin/SUMO pathways in human herpesviruses infection. Rev Med Virol 2016; 26:435-445. [DOI: 10.1002/rmv.1900] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/03/2016] [Accepted: 07/25/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Jin Gan
- MOE & MOH Key Laboratory of Medical Molecular Virology, School of Basic Medicine, Shanghai Medical College; Fudan University; Shanghai China
| | - Niu Qiao
- Department of Medical Systems Biology, School of Basic Medical Sciences; Department of Translational Medicine, Shanghai Public Health Clinical Center; Institutes of Biomedical Sciences, Fudan University; Shanghai China
| | - Roxanne Strahan
- Department of Microbiology & Immunology; University of Nevada, Reno School of Medicine; Reno NV USA
| | - Caixia Zhu
- MOE & MOH Key Laboratory of Medical Molecular Virology, School of Basic Medicine, Shanghai Medical College; Fudan University; Shanghai China
| | - Lei Liu
- Department of Medical Systems Biology, School of Basic Medical Sciences; Department of Translational Medicine, Shanghai Public Health Clinical Center; Institutes of Biomedical Sciences, Fudan University; Shanghai China
| | - Subhash C. Verma
- Department of Microbiology & Immunology; University of Nevada, Reno School of Medicine; Reno NV USA
| | - Fang Wei
- ShengYushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology; Shanghai Jiao Tong University; Shanghai China
| | - Qiliang Cai
- MOE & MOH Key Laboratory of Medical Molecular Virology, School of Basic Medicine, Shanghai Medical College; Fudan University; Shanghai China
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Kaposi's Sarcoma-Associated Herpesvirus Reduces Cellular Myeloid Differentiation Primary-Response Gene 88 (MyD88) Expression via Modulation of Its RNA. J Virol 2015; 90:180-8. [PMID: 26468534 DOI: 10.1128/jvi.02342-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/02/2015] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is a human gammaherpesvirus associated with several human malignancies. The replication and transcription activator (RTA) is necessary and sufficient for the switch from KSHV latency to lytic replication. Interleukin 1 (IL-1) is a major mediator for inflammation and plays an important role in both innate and adaptive immunity. Myeloid differentiation primary response gene 88 (MyD88) is an essential adaptor molecule for IL-1 as well as most Toll-like receptor signaling. In this study, we identified a novel mechanism by which KSHV interferes with host inflammation and immunity. KSHV RTA specifically reduces the steady-state protein levels of MyD88, and physiological levels of MyD88 are downregulated during KSHV lytic replication when RTA is expressed. The N-terminal region of RTA is required for the reduction of MyD88. Additional studies demonstrated that RTA targets MyD88 expression at the RNA level, inhibits RNA synthesis of MyD88, and may bind MyD88 RNA. Finally, RTA inhibits IL-1-mediated activation of NF-κB. Because IL-1 is abundant in the KS microenvironment and inhibits KSHV replication, this work may expand our understanding of how KSHV evades host inflammation and immunity for its survival in vivo. IMPORTANCE MyD88 is an important molecule for IL-1-mediated inflammation and Toll-like receptor (TLR) signaling. This work shows that KSHV inhibits MyD88 expression through a novel mechanism. KSHV RTA may bind to MyD88 RNA, suppresses RNA synthesis of MyD88, and inhibits IL-1-mediated signaling. This work may expand our understanding of how KSHV evades host inflammation and immunity.
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Wang Y, Yu K, Pei X, Zhang T, Guo Y, Wood C, Wang J. Activation and degradation of open reading frame 45 by the replication and transcription activator of Kaposi's sarcoma-associated herpesvirus. J Gen Virol 2015; 96:1883-9. [PMID: 25783474 DOI: 10.1099/vir.0.000125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The open reading frame 45 (ORF45) of the Kaposi's sarcoma-associated herpesvirus (KSHV) is an immediate-early phosphorylated tegument protein critical for viral escape from host immune surveillance. Its expression is upregulated by the viral replication and transcription activator (RTA), a key protein that controls the switch from latency to lytic replication. We report here that ORF45 expression was not only upregulated by RTA, but ORF45 could also be degraded by RTA in a proteasome-dependent manner. The ORF45 was activated by RTA via activation of the ORF45 promoter, and the promoter region from nt 69 271 to nt 69 026 was involved. In chronic KSHV infected TRE-BCBL-1 RTA cells, the endogenous ORF45 protein increased dramatically after the induction of RTA expression, but then decreased rapidly after 8 h post-induction. Our study suggests that RTA might control the kinetics of viral replication through fine-tuning of the level of ORF45 and other viral/host proteins.
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Affiliation(s)
- Ying Wang
- 1TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China 2Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, PR China 3Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, PR China
| | - Kai Yu
- 1TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China
| | - Xiuzhi Pei
- 1TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China
| | - Tianzheng Zhang
- 1TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China
| | - Yuying Guo
- 1TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China
| | - Charles Wood
- 4Nebraska Center for Virology and School of Biological Sciences, University of Nebraska, Lincoln, NE 68583, USA
| | - Jinzhong Wang
- 1TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin 300457, PR China 2Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, PR China 3Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, PR China
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Abstract
Molluscum contagiosum virus (MCV) is the causative agent of molluscum contagiosum (MC), the third most common viral skin infection in children, and one of the five most prevalent skin diseases worldwide. No FDA-approved treatments, vaccines, or commercially available rapid diagnostics for MCV are available. This review discusses several aspects of this medically important virus including: physical properties of MCV, MCV pathogenesis, MCV replication, and immune responses to MCV infection. Sequencing of the MCV genome revealed novel immune evasion molecules which are highlighted here. Special attention is given to the MCV MC159 and MC160 proteins. These proteins are FLIPs with homologs in gamma herpesviruses and in the cell. They are of great interest because each protein regulates apoptosis, NF-κB, and IRF3. However, the mechanism that each protein uses to impart its effects is different. It is important to elucidate how MCV inhibits immune responses; this knowledge contributes to our understanding of viral pathogenesis and also provides new insights into how the immune system neutralizes virus infections.
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