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Human Gammaherpesvirus 8 Oncogenes Associated with Kaposi’s Sarcoma. Int J Mol Sci 2022; 23:ijms23137203. [PMID: 35806208 PMCID: PMC9266852 DOI: 10.3390/ijms23137203] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 01/01/2023] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV), also known as human gammaherpesvirus 8 (HHV-8), contains oncogenes and proteins that modulate various cellular functions, including proliferation, differentiation, survival, and apoptosis, and is integral to KSHV infection and oncogenicity. In this review, we describe the most important KSHV genes [ORF 73 (LANA), ORF 72 (vCyclin), ORF 71 or ORFK13 (vFLIP), ORF 74 (vGPCR), ORF 16 (vBcl-2), ORF K2 (vIL-6), ORF K9 (vIRF 1)/ORF K10.5, ORF K10.6 (vIRF 3), ORF K1 (K1), ORF K15 (K15), and ORF 36 (vPK)] that have the potential to induce malignant phenotypic characteristics of Kaposi’s sarcoma. These oncogenes can be explored in prospective studies as future therapeutic targets of Kaposi’s sarcoma.
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Nalwoga A, Roshan R, Moore K, Marshall V, Miley W, Labo N, Nakibuule M, Cose S, Rochford R, Newton R, Whitby D. Kaposi's sarcoma-associated herpesvirus T cell responses in HIV seronegative individuals from rural Uganda. Nat Commun 2021; 12:7323. [PMID: 34916520 PMCID: PMC8677732 DOI: 10.1038/s41467-021-27623-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 12/02/2021] [Indexed: 11/09/2022] Open
Abstract
T cell responses to Kaposi's sarcoma-associated herpesvirus (KSHV) are likely essential in the control of KSHV infection and protection from associated disease, but remain poorly characterised. KSHV prevalence in rural Uganda is high at >90%. Here we investigate IFN- γ T cell responses to the KSHV proteome in HIV-negative individuals from a rural Ugandan population. We use an ex-vivo IFN- γ ELISpot assay with overlapping peptide pools spanning 83 KSHV open reading frames (ORF) on peripheral blood mononuclear cells (PBMC) from 116 individuals. KSHV-specific T cell IFN- γ responses are of low intensity and heterogeneous, with no evidence of immune dominance; by contrast, IFN- γ responses to Epstein-Barr virus, Cytomegalovirus and influenza peptides are frequent and intense. Individuals with KSHV DNA in PBMC have higher IFN- γ responses to ORF73 (p = 0.02) and lower responses to K8.1 (p = 0.004) when compared with those without KSHV DNA. In summary, we demonstrate low intensity, heterogeneous T cell responses to KSHV in immune-competent individuals.
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Affiliation(s)
- Angela Nalwoga
- MRC/UVRI and LSHTM Uganda Research Unit, Entebbe, Uganda.
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA.
| | - Romin Roshan
- Viral Oncology Section, AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Kyle Moore
- Viral Oncology Section, AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Vickie Marshall
- Viral Oncology Section, AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Wendell Miley
- Viral Oncology Section, AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Nazzarena Labo
- Viral Oncology Section, AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | | | - Stephen Cose
- MRC/UVRI and LSHTM Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, London, UK
| | - Rosemary Rochford
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | | | - Denise Whitby
- Viral Oncology Section, AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, USA.
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Long W, Zhao G, Wu Y, Liu Y. Gallic acid inhibits Kaposi's Sarcoma-associated herpesvirus lytic reactivation by suppressing RTA transcriptional activities. Food Sci Nutr 2021; 9:847-854. [PMID: 33598168 PMCID: PMC7866607 DOI: 10.1002/fsn3.2048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/12/2020] [Accepted: 11/21/2020] [Indexed: 12/17/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV), an oncogenic virus, has two life cycle modes: the latent and lytic phases. KSHV lytic reactivation is known to be important both for viral propagation and for KSHV-induced tumorigenesis. The KSHV replication and transcription activator (RTA) protein is essential for lytic reactivation. Gallic acid (GA), one of the most abundant phenolic acids in the plant kingdom, has been shown potential chemotherapeutic efficacy against microbial and cancer. However, the effects of GA on KSHV replication and KSHV-induced tumorigenesis have not yet been reported. Here, we report that GA induces apoptotic cell death in BCBL-1 cells in a dose-dependent manner. GA inhibits KSHV reactivation and reduces the production of progeny virus from KSHV-harboring cells. GA inhibits RTA transcriptional activities by suppressing its binding to target gene promoters. These results suggest that GA may represent a novel strategy for the treatment of KSHV infection and KSHV-associated lymphomas.
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Affiliation(s)
- Wen‐Ying Long
- Central LaboratoryThe Fourth Affiliated HospitalZhejiang University School of MedicineN1 Shangcheng AvenueYiwu322000China
| | - Guo‐hua Zhao
- Department of NeurologyThe Fourth Affiliated HospitalZhejiang University School of MedicineN1 Shangcheng AvenueYiwu322000China
| | - Yao Wu
- Central LaboratoryThe Fourth Affiliated HospitalZhejiang University School of MedicineN1 Shangcheng AvenueYiwu322000China
| | - Ying Liu
- Central LaboratoryThe Fourth Affiliated HospitalZhejiang University School of MedicineN1 Shangcheng AvenueYiwu322000China
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Nuclear Localization and Cleavage of STAT6 Is Induced by Kaposi's Sarcoma-Associated Herpesvirus for Viral Latency. PLoS Pathog 2017; 13:e1006124. [PMID: 28099521 PMCID: PMC5242515 DOI: 10.1371/journal.ppat.1006124] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 12/13/2016] [Indexed: 12/18/2022] Open
Abstract
Emerging evidence implies that STAT6 plays an important role in both the adaptive and innate immune responses to virus infection. Kaposi’s sarcoma-associated herpesvirus (KSHV) is an oncogenic γ-herpesvirus agent associated with several human malignancies, including Kaposi’s sarcoma (KS) and primary effusion lymphomas (PELs). Previously, we demonstrated that KSHV blocks IL-4-induced STAT6 phosphorylation and retains a basal IL-13/STAT6 constitutive activation for cell survival and proliferation. However, the mechanism by which KSHV regulates STAT6 remains largely unknown. Here, we found that KSHV-encoded LANA interacts with STAT6 and promotes nuclear localization of STAT6 independent of the tyrosine 641-phosphorylation state. Moreover, nuclear localization of STAT6 is also dramatically increased in KS tissue. The latent antigen LANA induces serine protease-mediated cleavage of STAT6 in the nucleus, where the cleaved STAT6 lacking transactivation domain functions as a dominant-negative regulator to repress transcription of Replication and Transcription Activator (RTA) and in turn shut off viral lytic replication. Blockade of STAT6 by small interference RNA dramatically enhances expression of RTA, and in turn reduces KSHV-infected endothelial cell growth and colony formation. Taken together, these results suggest that nuclear localization and cleavage of STAT6 is important for modulating the viral latency and pathogenesis of KSHV. STAT6, a member of the signal transducer and activator of transcription (STAT) family, has been shown to play an important role in viral infection. STAT6 activation is linked to reactivation of oncogenic herpesvirus and their associated cancers. However, the precise mechanism by which KSHV modulates STAT6 regulation remains unclear. In the present study, we demonstrate that KSHV induces nuclear localization and cleavage of STAT6 in both KSHV-infected B lymphoma and endothelial cells. Importantly, this effect is dependent on LANA (a key latent antigen) expression and leads to inhibition of viral lytic replication. Herein, we provide a previously uncharacterized description of how STAT6 plays an inhibitory role in the pathogenesis of oncogenic viruses.
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Zhang T, Wang L. Epidemiology of Kaposi's sarcoma‐associated herpesvirus in Asia: Challenges and opportunities. J Med Virol 2016; 89:563-570. [DOI: 10.1002/jmv.24662] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2016] [Indexed: 01/12/2023]
Affiliation(s)
- Tiejun Zhang
- Department of EpidemiologySchool of Public HealthFudan UniversityShanghaiChina
| | - Linding Wang
- Department of MicrobiologyAnhui Medical UniversityHefeiAnhuiChina
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K1 and K15 of Kaposi's Sarcoma-Associated Herpesvirus Are Partial Functional Homologues of Latent Membrane Protein 2A of Epstein-Barr Virus. J Virol 2015; 89:7248-61. [PMID: 25948739 DOI: 10.1128/jvi.00839-15] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 04/27/2015] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED The human herpesviruses Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are associated with Hodgkin's lymphoma (HL) and Primary effusion lymphomas (PEL), respectively, which are B cell malignancies that originate from germinal center B cells. PEL cells but also a quarter of EBV-positive HL tumor cells do not express the genuine B cell receptor (BCR), a situation incompatible with survival of normal B cells. EBV encodes LMP2A, one of EBV's viral latent membrane proteins, which likely replaces the BCR's survival signaling in HL. Whether KSHV encodes a viral BCR mimic that contributes to oncogenesis is not known because an experimental model of KSHV-mediated B cell transformation is lacking. We addressed this uncertainty with mutant EBVs encoding the KSHV genes K1 or K15 in lieu of LMP2A and infected primary BCR-negative (BCR(-)) human B cells with them. We confirmed that the survival of BCR(-) B cells and their proliferation depended on an active LMP2A signal. Like LMP2A, the expression of K1 and K15 led to the survival of BCR(-) B cells prone to apoptosis, supported their proliferation, and regulated a similar set of cellular target genes. K1 and K15 encoded proteins appear to have noncomplementing, redundant functions in this model, but our findings suggest that both KSHV proteins can replace LMP2A's key activities contributing to the survival, activation and proliferation of BCR(-) PEL cells in vivo. IMPORTANCE Several herpesviruses encode oncogenes that are receptor-like proteins. Often, they are constitutively active providing important functions to the latently infected cells. LMP2A of Epstein-Barr virus (EBV) is such a receptor that mimics an activated B cell receptor, BCR. K1 and K15, related receptors of Kaposi's sarcoma-associated herpesvirus (KSHV) expressed in virus-associated tumors, have less obvious functions. We found in infection experiments that both viral receptors of KSHV can replace LMP2A and deliver functions similar to the endogenous BCR. K1, K15, and LMP2A also control the expression of a related set of cellular genes in primary human B cells, the target cells of EBV and KSHV. The observed phenotypes, as well as the known characteristics of these genes, argue for their contributions to cellular survival, B cell activation, and proliferation. Our findings provide one possible explanation for the tumorigenicity of KSHV, which poses a severe problem in immunocompromised patients.
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Liu G, Yu FX, Kim YC, Meng Z, Naipauer J, Looney DJ, Liu X, Gutkind JS, Mesri EA, Guan KL. Kaposi sarcoma-associated herpesvirus promotes tumorigenesis by modulating the Hippo pathway. Oncogene 2014; 34:3536-46. [PMID: 25195862 DOI: 10.1038/onc.2014.281] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 07/18/2014] [Accepted: 07/23/2014] [Indexed: 12/23/2022]
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) is an oncogenic virus and the culprit behind the human disease Kaposi sarcoma (KS), an AIDS-defining malignancy. KSHV encodes a viral G-protein-coupled receptor (vGPCR) critical for the initiation and progression of KS. In this study, we identified that YAP/TAZ, two homologous oncoproteins inhibited by the Hippo tumor suppressor pathway, are activated in KSHV-infected cells in vitro, KS-like mouse tumors and clinical human KS specimens. The KSHV-encoded vGPCR acts through Gq/11 and G12/13 to inhibit the Hippo pathway kinases Lats1/2, promoting the activation of YAP/TAZ. Furthermore, depletion of YAP/TAZ blocks vGPCR-induced cell proliferation and tumorigenesis in a xenograft mouse model. The vGPCR-transformed cells are sensitive to pharmacologic inhibition of YAP. Our study establishes a pivotal role of the Hippo pathway in mediating the oncogenic activity of KSHV and development of KS, and also suggests a potential of using YAP inhibitors for KS intervention.
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Affiliation(s)
- G Liu
- 1] School of Life Sciences, Shandong University, Jinan, China [2] Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA
| | - F-X Yu
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA
| | - Y C Kim
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA
| | - Z Meng
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA
| | - J Naipauer
- Department of Microbiology and Immunology and Viral Oncology Program, Miami Center for AIDS Research, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA
| | - D J Looney
- Department of Medicine, VA San Diego Healthcare System, The University of California, San Diego, La Jolla, CA, USA
| | - X Liu
- School of Life Sciences, Shandong University, Jinan, China
| | - J S Gutkind
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - E A Mesri
- Department of Microbiology and Immunology and Viral Oncology Program, Miami Center for AIDS Research, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA
| | - K-L Guan
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA
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Wu J, Xu Y, Mo D, Huang P, Sun R, Huang L, Pan S, Xu J. Kaposi's sarcoma-associated herpesvirus (KSHV) vIL-6 promotes cell proliferation and migration by upregulating DNMT1 via STAT3 activation. PLoS One 2014; 9:e93478. [PMID: 24675762 PMCID: PMC3968168 DOI: 10.1371/journal.pone.0093478] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 03/04/2014] [Indexed: 12/24/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically associated with Kaposi's sarcoma (KS), the most common AIDS-related malignancy. KSHV vIL-6 promotes KS development, but the exact mechanisms remain unclear. Here, we reported that KSHV vIL-6 enhanced the expression of DNA methyltransferase 1 (DNMT1) in endothelial cells,increased the global genomic DNA methylation, and promoted cell proliferation and migration. And this effect could be blocked by the DNA methyltransferase inhibitor, 5-azadeoxycytidine. We also showed that vIL-6 induced up-regulation of DNMT1 was dependent on STAT3 activation. Therefore, the present study suggests that vIL-6 plays a role in KS tumorigenesis partly by activating DNMT1 and inducing aberrant DNA methylation, and it might be a potential target for KS therapy.
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Affiliation(s)
- Jing Wu
- Department of Respiratory Medicine, Nanjing Chest Hospital, Nanjing, China
| | - Yuqiao Xu
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Dongping Mo
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Peijun Huang
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- National Key Clinical Department of Laboratory Medicine, Nanjing, China
| | - Ruihong Sun
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Lei Huang
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Shiyang Pan
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- National Key Clinical Department of Laboratory Medicine, Nanjing, China
- * E-mail: (JX); (SP)
| | - Jian Xu
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- National Key Clinical Department of Laboratory Medicine, Nanjing, China
- * E-mail: (JX); (SP)
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Scholz BA, Harth-Hertle ML, Malterer G, Haas J, Ellwart J, Schulz TF, Kempkes B. Abortive lytic reactivation of KSHV in CBF1/CSL deficient human B cell lines. PLoS Pathog 2013; 9:e1003336. [PMID: 23696732 PMCID: PMC3656114 DOI: 10.1371/journal.ppat.1003336] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/20/2013] [Indexed: 11/25/2022] Open
Abstract
Since Kaposi's sarcoma associated herpesvirus (KSHV) establishes a persistent infection in human B cells, B cells are a critical compartment for viral pathogenesis. RTA, the replication and transcription activator of KSHV, can either directly bind to DNA or use cellular DNA binding factors including CBF1/CSL as DNA adaptors. In addition, the viral factors LANA1 and vIRF4 are known to bind to CBF1/CSL and modulate RTA activity. To analyze the contribution of CBF1/CSL to reactivation in human B cells, we have successfully infected DG75 and DG75 CBF1/CSL knock-out cell lines with recombinant KSHV.219 and selected for viral maintenance by selective medium. Both lines maintained the virus irrespective of their CBF1/CSL status. Viral reactivation could be initiated in both B cell lines but viral genome replication was attenuated in CBF1/CSL deficient lines, which also failed to produce detectable levels of infectious virus. Induction of immediate early, early and late viral genes was impaired in CBF1/CSL deficient cells at multiple stages of the reactivation process but could be restored to wild-type levels by reintroduction of CBF1/CSL. To identify additional viral RTA target genes, which are directly controlled by CBF1/CSL, we analyzed promoters of a selected subset of viral genes. We show that the induction of the late viral genes ORF29a and ORF65 by RTA is strongly enhanced by CBF1/CSL. Orthologs of ORF29a in other herpesviruses are part of the terminase complex required for viral packaging. ORF65 encodes the small capsid protein essential for capsid shell assembly. Our study demonstrates for the first time that in human B cells viral replication can be initiated in the absence of CBF1/CSL but the reactivation process is severely attenuated at all stages and does not lead to virion production. Thus, CBF1/CSL acts as a global hub which is used by the virus to coordinate the lytic cascade. Kaposi's sarcoma associated herpesvirus (KSHV) establishes a life-long persistent infection in B cells, which constitute the viral reservoir for reactivation and production of progeny virus. Viral reactivation is associated with multiple AIDS related malignancies including Kaposi's sarcoma, an endothelial tumor, and two B cell lymphoproliferative malignancies, the primary effusion lymphoma and the multicentric Castleman's disease. CBF1/CSL is a cellular DNA binding protein that can recruit transactivators or repressors to regulatory sites in the viral and cellular genome. The replication and transcription activator (RTA) plays an essential role in the switch between latency and lytic reactivation. RTA can either bind to DNA directly or is recruited to DNA via anchor proteins like CBF1/CSL and activates transcription. In this study we used a novel cell culture model to analyze the contribution of the CBF1/CSL protein to the process of viral reactivation in human B cells. Two isogenic CBF1/CSL proficient or deficient B cell lines were latently infected with recombinant KSHV. Lytic viral gene expression, viral replication and virus production were compared. Our results suggest that viral lytic gene expression is severely attenuated but not abolished at multiple stages before and after the onset of lytic replication while virus production is below detection levels in CBF1/CSL deficient B cells.
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Affiliation(s)
- Barbara A. Scholz
- Department of Gene Vectors, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich, Germany
| | - Marie L. Harth-Hertle
- Department of Gene Vectors, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich, Germany
| | - Georg Malterer
- Division of Pathway Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Juergen Haas
- Division of Pathway Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Joachim Ellwart
- Institute of Molecular Immunology, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich, Germany
| | - Thomas F. Schulz
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Bettina Kempkes
- Department of Gene Vectors, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich, Germany
- * E-mail:
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CTCF regulates Kaposi's sarcoma-associated herpesvirus latency transcription by nucleosome displacement and RNA polymerase programming. J Virol 2012. [PMID: 23192870 DOI: 10.1128/jvi.02283-12] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CCCTC-binding factor (CTCF) has been implicated in various aspects of viral and host chromatin organization and transcriptional control. We showed previously that CTCF binds to a cluster of three sites in the first intron of the Kaposi's sarcoma-associated herpesvirus (KSHV) multicistronic latency-associated transcript that encodes latency-associated nuclear antigen (LANA), viral cyclin (vCyclin), vFLIP, viral microRNAs, and kaposin. We show here that these CTCF binding sites regulate mRNA production, RNA polymerase II (RNAPII) programming, and nucleosome organization of the KSHV latency transcript control region. We also show that KSHV bacmids lacking these CTCF binding sites have elevated and altered ratios of spliced latency transcripts. CTCF binding site mutations altered RNAPII and RNAPII-accessory factor interactions with the latency control region. CTCF binding sites were required for the in vitro recruitment of RNAPII to the latency control region, suggesting that direct interactions between CTCF and RNAPII contribute to transcription regulation. Histone modifications in the latency control region were also altered by mutations in the CTCF binding sites. Finally, we show that CTCF binding alters the regular phasing of nucleosomes in the latency gene transcript and intron, suggesting that nucleosome positioning can be an underlying biochemical mechanism of CTCF function. We propose that RNAPII interactions and nucleosome displacement serve as a biochemical basis for programming RNAPII in the KSHV transcriptional control region.
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Montaner S, Kufareva I, Abagyan R, Gutkind JS. Molecular mechanisms deployed by virally encoded G protein-coupled receptors in human diseases. Annu Rev Pharmacol Toxicol 2012; 53:331-54. [PMID: 23092247 DOI: 10.1146/annurev-pharmtox-010510-100608] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
G protein-coupled receptors (GPCRs) represent the largest family of cell surface molecules involved in signal transduction. Surprisingly, open reading frames for multiple GPCRs were hijacked in the process of coevolution between Herpesviridae family viruses and their human and mammalian hosts. Virally encoded GPCRs (vGPCRs) evolved as parts of viral genomes, and this evolution allowed the power of host GPCR signaling circuitries to be harnessed in order to ensure viral replicative success. Phylogenetically, vGPCRs are distantly related to human chemokine receptors, although they feature several unique characteristics. Here, we describe the molecular mechanisms underlying vGPCR-mediated viral pathogenesis. These mechanisms include constitutive activity, aberrant coupling to human G proteins and β-arrestins, binding and activation by human chemokines, and dimerization with other GPCRs expressed in infected cells. The likely structural basis for these molecular events is described for the two closest viral homologs of human GPCRs. This information may aid in the development of novel targeted therapeutic strategies against viral diseases.
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Affiliation(s)
- Silvia Montaner
- Department of Oncology and Diagnostic Sciences, Department of Pathology, and Greenebaum Cancer Center, University of Maryland, Baltimore, Maryland 21201, USA.
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12
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Sathish N, Wang X, Yuan Y. Tegument Proteins of Kaposi's Sarcoma-Associated Herpesvirus and Related Gamma-Herpesviruses. Front Microbiol 2012; 3:98. [PMID: 22435068 PMCID: PMC3304090 DOI: 10.3389/fmicb.2012.00098] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 02/28/2012] [Indexed: 12/12/2022] Open
Abstract
A herpesvirus virion is composed of a viral genomic DNA-containing capsid surrounded by a viral envelope with glycoprotein spikes on its surface. Located between the capsid and the outer viral envelope is the virion tegument layer. Though the majority of the virion proteins are located in the tegument, this layer is less studied and was thought to be an amorphous structure. Over the last decade, a number of studies have indicated the presence of organized tegument structures across the spectrum of herpesviruses, implicating tegument components in critical steps governing the viral life cycle. In the case of Kaposi’s sarcoma-associated herpesvirus (KSHV), the etiological agent of Kaposi’s sarcoma, several functions exerted by tegument proteins at different stages of the viral life cycle, inclusive of primary de novo infection and virion assembly, have been identified over the last several years. In this review, KSHV tegument components are cataloged and the occurrence of organized tegument structures in KSHV, built through interactions amongst the different virion proteins, is discussed in depth. The significant functional roles of the KSHV tegument proteins at different stages of the viral life cycle are elaborated under separate headings. Definitive functional roles exerted by tegument proteins of related gamma-herpesviruses are also discussed. Since tegument proteins play key roles during viral assembly, viral entry, and represent an important interface for virus–host interactions, further research in this area should provide detailed insights into the functional capacity of the KSHV tegument, resulting in a better understanding of the viral life cycle.
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Affiliation(s)
- Narayanan Sathish
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal Bhopal, Madhya Pradesh, India
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Ballestas ME, Kaye KM. The latency-associated nuclear antigen, a multifunctional protein central to Kaposi's sarcoma-associated herpesvirus latency. Future Microbiol 2012; 6:1399-413. [PMID: 22122438 DOI: 10.2217/fmb.11.137] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Latency-associated nuclear antigen (LANA) is encoded by the Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) open reading frame 73. LANA is expressed during latent KSHV infection of cells, including tumor cells, such as primary effusion lymphoma, KS and multicentric Castleman's disease. Latently infected cells have multiple extrachromosomal copies of covalently closed circular KSHV genomes (episomes) that are stably maintained in proliferating cells. LANA's best characterized function is that of mediating episome persistence. It does so by binding terminal repeat sequences to the chromosomal matrix, thus ensuring episome replication with each cell division and efficient DNA segregation to daughter nuclei after mitosis. To achieve these functions, LANA associates with different host cell proteins, including chromatin-associated proteins and proteins involved in DNA replication. In addition to episome maintenance, LANA has transcriptional regulatory effects and affects cell growth. LANA exerts these functions through interactions with different cell proteins.
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Affiliation(s)
- Mary E Ballestas
- Department of Pediatrics, Division of Infectious Diseases, University of Alabama in Birmingham, School of Medicine, Children's Harbor Building, Room 148, 1600 6th Ave South, Birmingham, AL 35233, USA
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Ashizawa A, Higashi C, Masuda K, Ohga R, Taira T, Fujimuro M. The Ubiquitin System and Kaposi's Sarcoma-Associated Herpesvirus. Front Microbiol 2012; 3:66. [PMID: 22375140 PMCID: PMC3284729 DOI: 10.3389/fmicb.2012.00066] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 02/07/2012] [Indexed: 11/28/2022] Open
Abstract
Ubiquitination is a post-translational modification in which one or more ubiquitin molecules are covalently linked to lysine residues of target proteins. The ubiquitin system plays a key role in the regulation of protein degradation, which contributes to cell signaling, vesicular trafficking, apoptosis, and immune regulation. Bacterial and viral pathogens exploit the cellular ubiquitin system by encoding their own proteins to serve their survival and replication in infected cells. Recent studies have revealed that Kaposi’s sarcoma-associated herpesvirus (KSHV) manipulates the ubiquitin system of infected cells to facilitate cell proliferation, anti-apoptosis, and evasion from immunity. This review summarizes recent developments in our understanding of the molecular mechanisms used by KSHV to interact with the cellular ubiquitin machinery.
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Affiliation(s)
- Akira Ashizawa
- Department of Molecular Cell Biology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi Yamanashi, Japan
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15
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Robey RC, Mletzko S, Bower M, Meys R, Boffito M, Nelson M, Bunker CB, Gotch FM. Ex-vivo recognition of late-lytic CD8 epitopes specific for Kaposi's sarcoma-associated herpesvirus (KSHV) by HIV/KSHV-coinfected individuals. Viral Immunol 2011; 24:211-20. [PMID: 21668362 DOI: 10.1089/vim.2010.0133] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi's sarcoma (KS), the most common cancer in individuals with untreated HIV/AIDS. Host control of KSHV infection and KS oncogenesis by CD8 T cells remains underexplored. Although KSHV CD8 epitopes have been identified, the responses they elicit are weak and little is known about their relative importance. We sought to make a direct comparison of the recognition of a selection of the best-described known epitopes by a cohort of KSHV-seropositive, HIV-co-infected individuals, in order to assess the relative dominance of these epitopes. We further sought to identify novel epitopes from within a candidate immunogenic protein encoded by KSHV ORF28. MHC binding and denaturation assays identified putative novel A*0201-restricted epitopes from within the late-lytic glycoprotein ORF28. Recognition of these candidate epitopes was tested in a cohort of KSHV-seropositive, HIV-1-seropositive, A*0201-positive individuals by ex vivo ELISPOT, and compared with recognition of nine previously described epitopes. One novel late-lytic epitope from ORF28 was recognized by 7.1% of individuals, and was used for further investigation of KSHV-specific T cells using multimer technology. One known late-lytic epitope from the glycoprotein-encoding K8.1 was recognized by 71.4% of individuals, and represented an immunodominant KSHV epitope, but was too hydrophobic for multimer synthesis. This study identifies two KSHV CD8 epitopes derived from late-lytic antigens that are recognized by KSHV-seropositive, HIV co-infected individuals, and will be useful in future immunological studies into the CD8 response against KSHV in similar patient cohorts.
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Affiliation(s)
- Rebecca C Robey
- Department of Immunology, Imperial College London, London, UK
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Kang H, Wiedmer A, Yuan Y, Robertson E, Lieberman PM. Coordination of KSHV latent and lytic gene control by CTCF-cohesin mediated chromosome conformation. PLoS Pathog 2011; 7:e1002140. [PMID: 21876668 PMCID: PMC3158054 DOI: 10.1371/journal.ppat.1002140] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 05/10/2011] [Indexed: 12/22/2022] Open
Abstract
Herpesvirus persistence requires a dynamic balance between latent and lytic cycle gene expression, but how this balance is maintained remains enigmatic. We have previously shown that the Kaposi's Sarcoma-Associated Herpesvirus (KSHV) major latency transcripts encoding LANA, vCyclin, vFLIP, v-miRNAs, and Kaposin are regulated, in part, by a chromatin organizing element that binds CTCF and cohesins. Using viral genome-wide chromatin conformation capture (3C) methods, we now show that KSHV latency control region is physically linked to the promoter regulatory region for ORF50, which encodes the KSHV immediate early protein RTA. Other linkages were also observed, including an interaction between the 5' and 3' end of the latency transcription cluster. Mutation of the CTCF-cohesin binding site reduced or eliminated the chromatin conformation linkages, and deregulated viral transcription and genome copy number control. siRNA depletion of CTCF or cohesin subunits also disrupted chromosomal linkages and deregulated viral latent and lytic gene transcription. Furthermore, the linkage between the latent and lytic control region was subject to cell cycle fluctuation and disrupted during lytic cycle reactivation, suggesting that these interactions are dynamic and regulatory. Our findings indicate that KSHV genomes are organized into chromatin loops mediated by CTCF and cohesin interactions, and that these inter-chromosomal linkages coordinate latent and lytic gene control.
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Affiliation(s)
- Hyojeung Kang
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- The Kyungpook National University, College of Pharmacy, Daegu, Korea
| | - Andreas Wiedmer
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Yan Yuan
- The University of Pennsylvania, School of Dentistry, Philadelphia, Pennsylvania, United States of America
| | - Erle Robertson
- The University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Paul M. Lieberman
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
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17
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Steitz J, Borah S, Cazalla D, Fok V, Lytle R, Mitton-Fry R, Riley K, Samji T. Noncoding RNPs of viral origin. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a005165. [PMID: 20719877 DOI: 10.1101/cshperspect.a005165] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Like their host cells, many viruses produce noncoding (nc)RNAs. These show diversity with respect to time of expression during viral infection, length and structure, protein-binding partners and relative abundance compared with their host-cell counterparts. Viruses, with their limited genomic capacity, presumably evolve or acquire ncRNAs only if they selectively enhance the viral life cycle or assist the virus in combating the host's response to infection. Despite much effort, identifying the functions of viral ncRNAs has been extremely challenging. Recent technical advances and enhanced understanding of host-cell ncRNAs promise accelerated insights into the RNA warfare mounted by this fascinating class of RNPs.
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Affiliation(s)
- Joan Steitz
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536-0812, USA.
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18
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Jham BC, Montaner S. The Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor: Lessons on dysregulated angiogenesis from a viral oncogene. J Cell Biochem 2010; 110:1-9. [PMID: 20213674 DOI: 10.1002/jcb.22524] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Tumor viruses can induce cell transformation by overcoming cellular defense mechanisms and promoting the ungoverned proliferation of infected cells. To this end, functionally related viral oncogenes have evolved in disparate viruses to over-ride key proliferative and survival intracellular pathways, thus assuring efficient viral replication and contributing to tumor formation. Indeed, the study of viral oncogenes has been a powerful tool for disclosing fundamental insights into these basic cellular processes. In this regard, the Kaposi's sarcoma-associated herpesvirus (KSHV or HHV8), the etiological agent of Kaposi's sarcoma (KS), is an exemplary model of an oncogenic virus that includes within its genome several homologues of cellular genes implicated in the regulation of cell proliferation and apoptosis. However, emerging evidence now points to a single KSHV gene, ORF74, encoding for the viral G protein-coupled receptor (vGPCR), as essential for KS development. Expressed in only a fraction of cells within KS lesions, this viral receptor induces tumorigenesis through both autocrine and paracrine mechanisms. Indeed, work from several laboratories has demonstrated that vGPCR can promote cell proliferation, enhance cell survival, modulate cell migration, stimulate angiogenesis, and recruit inflammatory cells, both in expressing cells, as well as in neighboring (bystander) cells. Examination of this powerful viral oncogene may expose novel targets for the treatment of patients with KS and could ultimately provide a unique perspective into how GPCRs, and specifically chemokine receptors, contribute to angiogenesis and tumorigenesis.
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Affiliation(s)
- Bruno C Jham
- Department of Oncology and Diagnostic Sciences, University of Maryland, Baltimore, Maryland 21201, USA
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19
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Array-based transcript profiling and limiting-dilution reverse transcription-PCR analysis identify additional latent genes in Kaposi's sarcoma-associated herpesvirus. J Virol 2010; 84:5565-73. [PMID: 20219929 DOI: 10.1128/jvi.02723-09] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is a B-lymphotropic herpesvirus strongly linked to both lymphoproliferative diseases and Kaposi's sarcoma. The viral latency program of KSHV is central to persistent infection and plays important roles in the pathogenesis of KSHV-related tumors. Up to six polypeptides and 18 microRNAs are known to be expressed in latency, but it is unclear if all major latency genes have been identified. Here, we have employed array-based transcript profiling and limiting-dilution reverse transcription-PCR (RT-PCR) methodologies to explore this issue in several KSHV-infected cell lines. Our results show that RNAs encoding the K1 protein are found at low levels in most latently infected cell lines. The gene encoding v-IL-6 is also expressed as a latent transcript in some contexts. Both genes encode powerful signaling molecules with particular relevance to B cell biology: K1 mimics signaling through the B cell receptor, and v-IL-6 promotes B cell survival. These data resolve earlier controversies about K1 and v-IL-6 expression and indicate that, in addition to core latency genes, some transcripts can be expressed in KSHV latency in a context-dependent manner.
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20
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Alcendor DJ, Knobel SM, Desai P, Zhu WQ, Vigil HE, Hayward GS. KSHV downregulation of galectin-3 in Kaposi's sarcoma. Glycobiology 2009; 20:521-32. [PMID: 20040515 DOI: 10.1093/glycob/cwp204] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Galectins are a family of proteins that share an affinity for beta-galactoside containing glycoconjugates. In prostate, ovarian and breast cancer, downregulation of galectin-3 is associated with malignancy and tumor progression. Kaposi's sarcoma (KS) is characterized as an angioproliferative tumor of vascular endothelial cells and produces rare B cell lymphoproliferative diseases in the form of primary effusion lymphomas and some forms of multicentric Castleman's disease. Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of KS. We found reduced levels of galectin-3 expression in a significant fraction of latency-associated nuclear antigen (LANA)-positive spindle cell regions in human archival KS tissue and as measured in KS tissue microarrays. Here we demonstrate that galectin-3 protein expression is downregulated 10-fold in 10-day KSHV-infected dermal microvascular endothelial cells (DMVEC) accompanied by downregulation of message. There is loss of galectin-3 staining in KSHV-infected DMVEC by dual labeled immunohistochemistry in LANA-positive spindle cells. We observed a consistent downregulation of galectin-3 by time-course transcriptional analysis. Of the galectins assayed, only galectin-1 was also downregulated in KSHV-infected DMVEC. We examined 86 KS tumors; 19 were LANA positive (22%) and 67 LANA negative (78%). All 86 tumors were found to be galectin-3 positive; 11 of 19 showed reduced expression of galectin-3 in LANA-positive spindle cell regions. Our data suggest that KSHV vFLIP and LANA are the viral genes targeting galectin-3 downregulation. The contribution of host factors to the pathogenesis of KS is essential for early detection and development of innovative therapies for treatment.
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Affiliation(s)
- Donald J Alcendor
- Meharry Medical College, School of Medicine, Comprehensive Center for AIDS Health Disparities Research and the Department of Microbial Pathogenesis and Immune Response, Hubbard Hospital 1005 Dr. D.B. Todd Jr. Blvd., Nashville, TN 37208-3599, USA.
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21
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Tempera I, Lieberman PM. Chromatin organization of gammaherpesvirus latent genomes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1799:236-45. [PMID: 19853673 DOI: 10.1016/j.bbagrm.2009.10.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 10/02/2009] [Accepted: 10/11/2009] [Indexed: 12/12/2022]
Abstract
The gammaherpesviruses are a subclass of the herpesvirus family that establish stable latent infections in proliferating lymphoid and epithelial cells. The latent genomes are maintained as multicopy chromatinized episomes that replicate in synchrony with the cellular genome. Importantly, most of the episomes do not integrate into the host chromosome. Therefore, it is essential that the viral "minichromosome" establish a chromatin structure that is suitable for gene expression, DNA replication, and chromosome segregation. Evidence suggests that chromatin organization is important for each of these functions and plays a regulatory role in the establishment and maintenance of latent infection. Here, we review recent studies on the chromatin organization of the human gammaherpesviruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV). We discuss the potential role of viral origins of DNA replication and viral encoded origin-binding proteins like EBNA1 and LANA in establishment of viral chromosome organization during latent infection. We also discuss the roles of host cell factors, like CTCF and cohesins, that contribute to higher-order chromosome structures that may be important for stable gene expression programs during latent infection in proliferating cells.
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22
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Emuss V, Lagos D, Pizzey A, Gratrix F, Henderson SR, Boshoff C. KSHV manipulates Notch signaling by DLL4 and JAG1 to alter cell cycle genes in lymphatic endothelia. PLoS Pathog 2009; 5:e1000616. [PMID: 19816565 PMCID: PMC2751827 DOI: 10.1371/journal.ppat.1000616] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 09/11/2009] [Indexed: 12/14/2022] Open
Abstract
Increased expression of Notch signaling pathway components is observed in Kaposi sarcoma (KS) but the mechanism underlying the manipulation of the canonical Notch pathway by the causative agent of KS, Kaposi sarcoma herpesvirus (KSHV), has not been fully elucidated. Here, we describe the mechanism through which KSHV directly modulates the expression of the Notch ligands JAG1 and DLL4 in lymphatic endothelial cells. Expression of KSHV-encoded vFLIP induces JAG1 through an NFkappaB-dependent mechanism, while vGPCR upregulates DLL4 through a mechanism dependent on ERK. Both vFLIP and vGPCR instigate functional Notch signalling through NOTCH4. Gene expression profiling showed that JAG1- or DLL4-stimulated signaling results in the suppression of genes associated with the cell cycle in adjacent lymphatic endothelial cells, indicating a role for Notch signaling in inducing cellular quiescence in these cells. Upregulation of JAG1 and DLL4 by KSHV could therefore alter the expression of cell cycle components in neighbouring uninfected cells during latent and lytic phases of viral infection, influencing cellular quiescence and plasticity. In addition, differences in signaling potency between these ligands suggest a possible complementary role for JAG1 and DLL4 in the context of KS.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Calcium-Binding Proteins/physiology
- Cell Cycle/genetics
- Cell Cycle/physiology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/physiology
- Endothelium, Vascular/virology
- Gene Expression Regulation, Viral
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/physiology
- Humans
- Intercellular Signaling Peptides and Proteins/physiology
- Jagged-1 Protein
- Lymphatic System/cytology
- Lymphatic System/physiology
- Lymphatic System/virology
- Membrane Proteins/physiology
- Oligonucleotide Array Sequence Analysis
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/physiology
- RNA, Messenger/genetics
- Receptor, Notch4
- Receptors, Notch/genetics
- Receptors, Notch/physiology
- Sarcoma, Kaposi/genetics
- Sarcoma, Kaposi/virology
- Serrate-Jagged Proteins
- Signal Transduction
- Up-Regulation
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Affiliation(s)
- Victoria Emuss
- Cancer Research UK Viral Oncology Group, UCL Cancer Institute, University College London, London, United Kingdom
| | - Dimitrios Lagos
- Cancer Research UK Viral Oncology Group, UCL Cancer Institute, University College London, London, United Kingdom
| | - Arnold Pizzey
- Research Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom
| | - Fiona Gratrix
- Cancer Research UK Viral Oncology Group, UCL Cancer Institute, University College London, London, United Kingdom
| | - Stephen R. Henderson
- Cancer Research UK Viral Oncology Group, UCL Cancer Institute, University College London, London, United Kingdom
| | - Chris Boshoff
- Cancer Research UK Viral Oncology Group, UCL Cancer Institute, University College London, London, United Kingdom
- * E-mail:
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23
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Robey RC, Lagos D, Gratrix F, Henderson S, Matthews NC, Vart RJ, Bower M, Boshoff C, Gotch FM. The CD8 and CD4 T-cell response against Kaposi's sarcoma-associated herpesvirus is skewed towards early and late lytic antigens. PLoS One 2009; 4:e5890. [PMID: 19536280 PMCID: PMC2691989 DOI: 10.1371/journal.pone.0005890] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 04/30/2009] [Indexed: 01/06/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is causally related to Kaposi's sarcoma (KS), the most common malignancy in untreated individuals with HIV/AIDS. The adaptive T-cell immune response against KSHV has not been fully characterized. To achieve a better understanding of the antigenic repertoire of the CD8 and CD4 T-cell responses against KSHV, we constructed a library of lentiviral expression vectors each coding for one of 31 individual KSHV open reading frames (ORFs). We used these to transduce monocyte-derived dendritic cells (moDCs) isolated from 14 KSHV-seropositive (12 HIV-positive) and 7 KSHV-seronegative (4 HIV-positive) individuals. moDCs were transduced with up to 3 KSHV ORFs simultaneously (ORFs grouped according to their expression during the viral life cycle). Transduced moDCs naturally process the KSHV genes and present the resulting antigens in the context of MHC class I and II. Transduced moDCs were cultured with purified autologous T cells and the CD8 and CD4 T-cell proliferative responses to each KSHV ORF (or group) was assessed using a CFSE dye-based assay. Two pools of early lytic KSHV genes ([ORF8/ORF49/ORF61] and [ORF59/ORF65/K4.1]) were frequently-recognized targets of both CD8 and CD4 T cells from KSHV seropositive individuals. One pool of late lytic KSHV genes ([ORF28/ORF36/ORF37]) was a frequently-recognized CD8 target and another pool of late genes ([ORF33/K1/K8.1]) was a frequently-recognized CD4 target. We report that both the CD8 and CD4 T-cell responses against KSHV are skewed towards genes expressed in the early and late phases of the viral lytic cycle, and identify some previously unknown targets of these responses. This knowledge will be important to future immunological investigations into KSHV and may eventually lead to the development of better immunotherapies for KSHV-related diseases.
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Affiliation(s)
- Rebecca C. Robey
- Department of Immunology, Imperial College London, London, United Kingdom
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Dimitrios Lagos
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Fiona Gratrix
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Stephen Henderson
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Nick C. Matthews
- Department of Immunology, Imperial College London, London, United Kingdom
| | - Richard J. Vart
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Mark Bower
- Department of Immunology, Imperial College London, London, United Kingdom
| | - Chris Boshoff
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Frances M. Gotch
- Department of Immunology, Imperial College London, London, United Kingdom
- * E-mail:
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24
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A systems biology approach to identify the combination effects of human herpesvirus 8 genes on NF-kappaB activation. J Virol 2009; 83:2563-74. [PMID: 19129458 DOI: 10.1128/jvi.01512-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Human herpesvirus 8 (HHV-8) is the etiologic agent of Kaposi's sarcoma and primary effusion lymphoma. Activation of the cellular transcription factor nuclear factor-kappa B (NF-kappaB) is essential for latent persistence of HHV-8, survival of HHV-8-infected cells, and disease progression. We used reverse-transfected cell microarrays (RTCM) as an unbiased systems biology approach to systematically analyze the effects of HHV-8 genes on the NF-kappaB signaling pathway. All HHV-8 genes individually (n = 86) and, additionally, all K and latent genes in pairwise combinations (n = 231) were investigated. Statistical analyses of more than 14,000 transfections identified ORF75 as a novel and confirmed K13 as a known HHV-8 activator of NF-kappaB. K13 and ORF75 showed cooperative NF-kappaB activation. Small interfering RNA-mediated knockdown of ORF75 expression demonstrated that this gene contributes significantly to NF-kappaB activation in HHV-8-infected cells. Furthermore, our approach confirmed K10.5 as an NF-kappaB inhibitor and newly identified K1 as an inhibitor of both K13- and ORF75-mediated NF-kappaB activation. All results obtained with RTCM were confirmed with classical transfection experiments. Our work describes the first successful application of RTCM for the systematic analysis of pathofunctions of genes of an infectious agent. With this approach, ORF75 and K1 were identified as novel HHV-8 regulatory molecules on the NF-kappaB signal transduction pathway. The genes identified may be involved in fine-tuning of the balance between latency and lytic replication, since this depends critically on the state of NF-kappaB activity.
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25
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Chaisuparat R, Hu J, Jham BC, Knight ZA, Shokat KM, Montaner S. Dual inhibition of PI3Kalpha and mTOR as an alternative treatment for Kaposi's sarcoma. Cancer Res 2008; 68:8361-8. [PMID: 18922908 DOI: 10.1158/0008-5472.can-08-0878] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rapamycin (or sirolimus), the prototypical inhibitor of the mammalian target of rapamycin (mTOR) and an immunosuppressant used for the prevention of renal transplant rejection, has recently emerged as an effective treatment for Kaposi's sarcoma (KS), an enigmatic vascular tumor and a model for pathologic angiogenesis. Indeed, recent work supports a role for mTOR as a central player in the transformation of endothelial cells by the KS-associated herpesvirus-encoded G protein-coupled receptor (vGPCR), the viral oncogene believed to be responsible for causing KS. However, emerging evidence that rapamycin may transiently promote the activation of Akt may limit its use as an anti-KS therapy. Here, we show that activation of Akt in endothelial cells expressing vGPCR is augmented by treatment with rapamycin, resulting in the up-regulation of several Akt proliferative and survival pathways. However, use of a novel dual phosphatidylinositol 3-kinase alpha (PI3Kalpha)/mTOR inhibitor, PI-103, effectively and independently blocked activation of both PI3K and mTOR in vGPCR-expressing endothelial cells. This resulted in more effective inhibition of endothelial cell proliferation and survival in vitro and tumor growth in vivo. Our results suggest that PI-103 may be an effective therapeutic option for the treatment of patients with KS. Moreover, as KS may serve as a model for pathologic angiogenesis, our results further provide the basis for the early assessment of PI-103 as an antiangiogenic chemotherapeutic.
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Affiliation(s)
- Risa Chaisuparat
- Department of Oncology and Diagnostic Sciences and Greenebaum Cancer Center, University of Maryland, Baltimore, Maryland 21201, USA
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26
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Wang X, Herr RA, Hansen T. Viral and cellular MARCH ubiquitin ligases and cancer. Semin Cancer Biol 2008; 18:441-50. [PMID: 18948196 DOI: 10.1016/j.semcancer.2008.09.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Accepted: 09/26/2008] [Indexed: 11/18/2022]
Abstract
Covalent conjugation of proteins with ubiquitin is one the most important post-translational modifications because it controls intracellular protein trafficking typically resulting in protein degradation. Frequently ubiquitinated proteins are targeted to the proteasome for degradation in the cytosol. However, ubiquitinated membrane bound proteins can also be targeted for endocytosis and degradation in the lysosome. Ubiquitin-dependent degradation pathways have clear cancer relevance due to their integral involvement in protein quality control, regulation of immune responses, signal transduction, and cell cycle regulation. In spite of its fundamental importance, little is known regarding how proteins are specifically identified for ubiquitin-dependent degradation. In this article we review a newly discovered family of viral and cellular ubiquitin ligases called MARCH proteins. Recent studies of MARCH proteins define new paradigms showing how ubiquitin E3 ligases determine the intracellular location and fate of proteins.
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Affiliation(s)
- Xiaoli Wang
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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27
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Abstract
Epstein Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are found together in approximately 80% of primary effusion lymphomas (PEL), but their contribution to these cancers is unclear. We found that dominant-negative derivatives of EBNA1 inhibited EBV-positive PEL cells from forming colonies. Those rare PEL cells that proliferated after expression of the dominant-negative derivatives usually expressed these derivatives at low or undetectable levels and continued to maintain their EBV genomes. Those proliferating cells expressing higher levels of the derivatives expressed mutant derivatives that could not bind DNA. These findings indicate that EBV is required to sustain proliferation, as measured by colony formation of dually infected PEL cells. The dominant-negative derivatives of EBNA1 had no effect on the colony-forming ability of five EBV-negative, KSHV-negative hematopoietic cell lines. Surprisingly, they did inhibit the colony-forming ability of EBV-negative, KSHV-positive PEL cells. The small fraction of cells that continued to proliferate expressed only mutants of the EBNA1 derivatives that could no longer bind DNA. These findings indicate that the site-specific DNA-binding activity of EBNA1 or its derivatives when expressed efficiently in EBV-negative, KSHV-positive PEL cells inhibits their colony formation possibly through their binding to the KSHV genome.
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Affiliation(s)
- Amanda A Mack
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, WI 53706, USA
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28
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May JS, Smith CM, Gill MB, Stevenson PG. An essential role for the proximal but not the distal cytoplasmic tail of glycoprotein M in murid herpesvirus 4 infection. PLoS One 2008; 3:e2131. [PMID: 18461133 PMCID: PMC2329910 DOI: 10.1371/journal.pone.0002131] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Accepted: 03/31/2008] [Indexed: 01/08/2023] Open
Abstract
Murid herpesvirus-4 (MuHV-4) provides a tractable model with which to define common, conserved features of gamma-herpesvirus biology. The multi-membrane spanning glycoprotein M (gM) is one of only 4 glycoproteins that are essential for MuHV-4 lytic replication. gM binds to gN and is thought to function mainly secondary envelopment and virion egress, for which several predicted trafficking motifs in its C-terminal cytoplasmic tail could be important. We tested the contribution of the gM cytoplasmic tail to MuHV-4 lytic replication by making recombinant viruses with varying C-terminal deletions. Removing an acidic cluster and a distal YXXΦ motif altered the capsid distribution somewhat in infected cells but had little effect on virus replication, either in vitro or in vivo. In contrast, removing a proximal YXXΦ motif as well completely prevented productive replication. gM was still expressed, but unlike its longer forms showed only limited colocalization with co-transfected gN, and in the context of whole virus appeared to support gN expression less well. We conclude that some elements of the gM cytoplasmic tail are dispensible for MuHV-4 replication, but the tail as a whole is not.
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Affiliation(s)
- Janet S May
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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29
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Shin YC, Joo CH, Gack MU, Lee HR, Jung JU. Kaposi's sarcoma-associated herpesvirus viral IFN regulatory factor 3 stabilizes hypoxia-inducible factor-1 alpha to induce vascular endothelial growth factor expression. Cancer Res 2008; 68:1751-9. [PMID: 18339855 DOI: 10.1158/0008-5472.can-07-2766] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent associated with Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. Hypoxia-inducible factor-1 (HIF-1) is the master regulator of both developmental and pathologic angiogenesis, composed of an oxygen-sensitive alpha-subunit and a constitutively expressed beta-subunit. HIF-1 activity in tumors depends on the availability of the HIF-1 alpha subunit, the levels of which are increased under hypoxic conditions. Recent studies have shown that HIF-1 plays an important role in KSHV reactivation from latency and pathogenesis. Here, we report a novel mechanism by which KSHV activates HIF-1 activity. Specific interaction between KSHV viral IFN regulatory factor 3 (vIRF3) and the HIF-1 alpha subunit led to the HIF-1 alpha stabilization and transcriptional activation, which induced vascular endothelial growth factor expression and ultimately facilitated endothelial tube formation. Remarkably, the central domain of vIRF3, containing double alpha-helix motifs, was sufficient not only for binding to HIF-1 alpha but also for blocking its degradation in normoxic conditions. This indicates that KSHV has developed a unique mechanism to enhance HIF-1 alpha protein stability and transcriptional activity by incorporating a viral homologue of cellular IRF gene into its genome, which may contribute to viral pathogenesis.
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Affiliation(s)
- Young C Shin
- Department of Microbiology and Molecular Genetics and Tumor Virology Division, New England Primate Research Center, Harvard Medical School, Southborough, MA 01772, USA.
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30
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Krown SE. AIDS-associated Kaposi's sarcoma: is there still a role for interferon alfa? Cytokine Growth Factor Rev 2007; 18:395-402. [PMID: 17656146 PMCID: PMC2041795 DOI: 10.1016/j.cytogfr.2007.06.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Interferon alfa (IFNalpha) was one of the first agents to be used therapeutically in AIDS-associated Kaposi's sarcoma (KS) more than 25 years ago, and induces tumor regression in a subset of patients. Although much has been learned about the clinical role of IFNalpha in KS treatment, little is currently known about the mechanism(s) by which IFNalpha causes KS regression. This is despite a growing understanding of both KS pathogenesis and relevant IFNalpha activities. To a large extent other agents have supplanted IFNalpha as treatments for KS, but there may still remain a therapeutic role for IFNalpha, possibly in combination with other agents targeting angiogenesis and/or HHV-8-encoded human gene homologs that encode proteins involved in cell cycle regulation and signaling.
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Affiliation(s)
- Susan E Krown
- Melanoma Sarcoma Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
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31
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Rose PP, Bogyo M, Moses AV, Früh K. Insulin-like growth factor II receptor-mediated intracellular retention of cathepsin B is essential for transformation of endothelial cells by Kaposi's sarcoma-associated herpesvirus. J Virol 2007; 81:8050-62. [PMID: 17507477 PMCID: PMC1951299 DOI: 10.1128/jvi.00249-07] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the pathological agent of Kaposi's sarcoma (KS), a tumor characterized by aberrant proliferation of endothelial-cell-derived spindle cells. Since in many cancers tumorigenesis is associated with an increase in the activity of the cathepsin family, we studied the role of cathepsins in KS using an in vitro model of KSHV-mediated endothelial cell transformation. Small-molecule inhibitors and small interfering RNA (siRNA) targeting CTSB, but not other cathepsins, inhibited KSHV-induced postconfluent proliferation and the formation of spindle cells and foci of dermal microvascular endothelial cells. Interestingly, neither CTSB mRNA nor CTSB protein levels were induced in endothelial cells latently infected with KSHV. Secretion of CTSB was strongly diminished upon KSHV infection. Increased targeting of CTSB to endosomes was caused by the induction by KSHV of the expression of insulin-like growth factor-II receptor (IGF-IIR), a mannose-6-phosphate receptor (M6PR) that binds to cathepsins. Inhibition of IGF-IIR/M6PR expression by siRNA released CTSB for secretion. In contrast to the increased cathepsin secretion observed in most other tumors, viral inhibition of CTSB secretion via induction of an M6PR is crucial for the transformation of endothelial cells.
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MESH Headings
- Antigens, Viral/genetics
- Antigens, Viral/metabolism
- Apoptosis/physiology
- Cathepsin B/antagonists & inhibitors
- Cathepsin B/genetics
- Cathepsin B/metabolism
- Cell Transformation, Neoplastic
- Cells, Cultured
- Contact Inhibition
- Dipeptides/metabolism
- Endothelial Cells/cytology
- Endothelial Cells/physiology
- Enzyme Precursors/antagonists & inhibitors
- Enzyme Precursors/genetics
- Enzyme Precursors/metabolism
- Herpesvirus 8, Human/physiology
- Humans
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Receptor, IGF Type 2/genetics
- Receptor, IGF Type 2/metabolism
- Sarcoma, Kaposi
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Affiliation(s)
- Patrick P Rose
- Vaccine and Gene Therapy Institute, Oregon Health and Science University, Portland, OR 97239, USA
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32
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Vart RJ, Nikitenko LL, Lagos D, Trotter MWB, Cannon M, Bourboulia D, Gratrix F, Takeuchi Y, Boshoff C. Kaposi's sarcoma-associated herpesvirus-encoded interleukin-6 and G-protein-coupled receptor regulate angiopoietin-2 expression in lymphatic endothelial cells. Cancer Res 2007; 67:4042-51. [PMID: 17483315 DOI: 10.1158/0008-5472.can-06-3321] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Kaposi's sarcoma (KS) is caused by Kaposi's sarcoma-associated herpesvirus (KSHV) and consists of proliferating spindle cells, which are related to lymphatic endothelial cells (LEC). Angiopoietin-2 (Ang2) is a secreted proangiogenic and lymphangiogenic molecule. Here, we show the expression of Ang2 protein in KS and confirm that KSHV infection up-regulates Ang2 in LEC. We show that a paracrine mechanism contributes to this up-regulation. A lentiviral library of individual KSHV-encoding genes, comprising the majority of known latent genes and a selection of lytic viral genes, was constructed to investigate the underlying mechanism of this up-regulation. Two lytic genes, viral interleukin-6 (vIL6) and viral G-protein-coupled receptor (vGPCR), up-regulated Ang2 expression in LEC. Both vIL6 and vGPCR are expressed in KSHV-infected LEC and caused up-regulation of Ang2 in a paracrine manner. KSHV, vIL6, and vGPCR up-regulated Ang2 through the mitogen-activated protein kinase (MAPK) pathway. Gene expression microarray analysis identified several other angiogenic molecules affected by KSHV, including the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) axis, which is also affected by vIL6 and vGPCR in LEC, and matrix metalloproteinases, which could act in concert with Ang2 to contribute to KS development. These findings support the paracrine and autocrine roles of the lytic KSHV-encoded proteins, vIL6 and vGPCR, in KS pathogenesis and identify Ang2 as a potential therapeutic target for this neoplasm.
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MESH Headings
- Angiopoietin-2/biosynthesis
- Angiopoietin-2/genetics
- Endothelial Cells/metabolism
- Endothelial Cells/virology
- Gene Expression Regulation, Neoplastic
- Gene Library
- Herpesvirus 8, Human/genetics
- Humans
- Interleukin-6/genetics
- Interleukin-6/metabolism
- MAP Kinase Signaling System
- Mitogen-Activated Protein Kinases/metabolism
- Neovascularization, Pathologic/genetics
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/virology
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Sarcoma, Kaposi/blood supply
- Sarcoma, Kaposi/genetics
- Sarcoma, Kaposi/metabolism
- Sarcoma, Kaposi/virology
- Up-Regulation
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Affiliation(s)
- Richard J Vart
- Cancer Research U.K. Viral Oncology Group, Wolfson Institute for Biomedical Research, University College London, London, United Kingdom
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33
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Pyakurel P, Pak F, Mwakigonja AR, Kaaya E, Biberfeld P. KSHV/HHV-8 and HIV infection in Kaposi's sarcoma development. Infect Agent Cancer 2007; 2:4. [PMID: 17270056 PMCID: PMC1800836 DOI: 10.1186/1750-9378-2-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2006] [Accepted: 02/02/2007] [Indexed: 12/24/2022] Open
Abstract
Kaposi's sarcoma (KS) is a highly and abnormally vascularized tumor-like lesion affecting the skin, lymphnodes and viscera, which develops from early inflammatory stages of patch/plaque to late, nodular tumors composed predominant of spindle cells (SC). These SC are infected with the Kaposi's sarcoma-associated herpesvirus or human herpesvirus-8 (KSHV/HHV-8). KS is promoted during HIV infection by various angiogenic and pro-inflammatory factors including HIV-Tat. The latency associated nuclear antigen type 1 (LANA-1) protein is well expressed in SC, highly immunogenic and considered important in the generation and maintenance of HHV-8 associated malignancies. Various studies favour an endothelial origin of the KS SC, expressing "mixed" lymphatic and vascular endothelial cell markers, possibly representing hybrid phenotypes of endothelial cells (EC). A significant number of SC during KS development are apparently not HHV8 infected, which heterogeneity in viral permissiveness may indicate that non-infected SC may continuously be recruited in to the lesion from progenitor cells and locally triggered to develop permissiveness to HHV8 infection. In the present study various aspects of KS pathogenesis are discussed, focusing on the histopathological as well as cytogenetic and molecular genetic changes in KS.
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Affiliation(s)
- Pawan Pyakurel
- Immunopathology Lab., Department of Pathology and Oncology, Karolinska Institutet, 171-76 Solna, Stockholm, Sweden
| | - Fatemeh Pak
- Immunopathology Lab., Department of Pathology and Oncology, Karolinska Institutet, 171-76 Solna, Stockholm, Sweden
| | - Amos R Mwakigonja
- Immunopathology Lab., Department of Pathology and Oncology, Karolinska Institutet, 171-76 Solna, Stockholm, Sweden
- Muhimbili University College of Health Sciences, P. O. Box 65023, Dar-Es-Salaam, Tanzania
| | - Ephata Kaaya
- Immunopathology Lab., Department of Pathology and Oncology, Karolinska Institutet, 171-76 Solna, Stockholm, Sweden
- Muhimbili University College of Health Sciences, P. O. Box 65023, Dar-Es-Salaam, Tanzania
| | - Peter Biberfeld
- Immunopathology Lab., Department of Pathology and Oncology, Karolinska Institutet, 171-76 Solna, Stockholm, Sweden
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34
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Flanagan JM. Host epigenetic modifications by oncogenic viruses. Br J Cancer 2007; 96:183-8. [PMID: 17179991 PMCID: PMC2359987 DOI: 10.1038/sj.bjc.6603516] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Revised: 11/06/2006] [Accepted: 11/09/2006] [Indexed: 12/29/2022] Open
Abstract
Epigenetic alterations represent an important step in the initiation and progression of most human cancers, but it is difficult to differentiate the early cancer causing alterations from later consequences. Oncogenic viruses can induce transformation via expression of only a small number of viral genes. Therefore, the mechanisms by which oncogenic viruses cause cancer may provide clues as to which epigenetic alterations are critical in early carcinogenesis.
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Affiliation(s)
- J M Flanagan
- CR-UK Viral Oncology Group, Wolfson Institute for Biomedical Research, Gower Street, University College London, London WC1E 6BT, UK.
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35
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Ohmura-Hoshino M, Goto E, Matsuki Y, Aoki M, Mito M, Uematsu M, Hotta H, Ishido S. A novel family of membrane-bound E3 ubiquitin ligases. J Biochem 2006; 140:147-54. [PMID: 16954532 DOI: 10.1093/jb/mvj160] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
A novel E3 ubiquitin ligase family that consists of viral E3 ubiquitin ligases (E3s) and their mammalian homologues was recently discovered. These novel E3s are membrane-bound molecules that share the secondary structure and catalytic domain for E3 activity. All family members have two transmembrane regions at the center and a RING-CH domain at the amino terminus. Forced expression of these novel E3s has been shown to reduce the surface expression of various membrane proteins through ubiquitination of target molecules. Initial examples of viral E3s were identified in Kaposi's sarcoma associated herpesvirus (KSHV) and murine gamma-herpesvirus 68 (MHV-68) and have been designated as modulator of immune recognition (MIR) 1, 2 and mK3, respectively. MIR 1, 2 and mK3 are able to down-regulate MHC class I molecule expression, and mK3 is required to establish an effective latent viral infection in vivo. The first characterized mammalian homologue to MIR 1, 2 and mK3 is c-MIR/MARCH VIII. Forced expression of c-MIR/MARCH VIII down-regulates B7-2, a co-stimulatory molecule important for antigen presentation. Subsequently, several mammalian molecules related to c-MIR/MARCH VIII have been characterized and named as membrane associated RING-CH (MARCH) family. However, the precise physiological function of MARCH family members remains as yet unknown.
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Affiliation(s)
- Mari Ohmura-Hoshino
- Laboratory for Infectious Immunity, RIKEN Research Center for Allergy and Immunology 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045
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36
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Fujimuro M, Inoue H, Teishikata Y, Ishida Y, Yokosawa H. Apoptotic effect of ganciclovir on primary effusion lymphoma cells infected with Kaposi's sarcoma-associated herpesvirus. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2006; 25:635-45. [PMID: 16838851 DOI: 10.1080/15257770600686311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
We evaluated the cytotoxic and apoptotic effects of two purine nucleoside analogues, acyclovir (ACV) and ganciclovir (GCV), on lymphoma cells stably harboring Kaposi's sarcoma-associated herpesvirus (KSHV). Colorimetric caspase assay, flow cytometry, and immunoblotting with antibodies against apoptosis-related molecules revealed that GCV has cytotoxic activity toward KSHV-infected primary effusion lymphoma cells, while ACV has weak or little activity. In addition to the GCV-induced cytotoxicity, apoptosis via caspase-7/8, cleavage of poly(ADP-ribose) polymerase, and accumulation of p53 and p21 were induced by GCV treatment. In contrast, neither ACV nor GCV have cytotoxicity- or apoptosis-inducing activities toward uninfected cells.
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Affiliation(s)
- Masahiro Fujimuro
- Department of Biochemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
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37
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Gillet L, May JS, Colaco S, Stevenson PG. Glycoprotein L disruption reveals two functional forms of the murine gammaherpesvirus 68 glycoprotein H. J Virol 2006; 81:280-91. [PMID: 17050601 PMCID: PMC1797276 DOI: 10.1128/jvi.01616-06] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The herpesvirus glycoprotein H (gH) and gL associate to form a heterodimer that plays a central role in virus-driven membrane fusion. When archetypal alpha- or betaherpesviruses lack gL, gH misfolds and progeny virions are noninfectious. In order to define the role that gL plays in gamma-2 herpesvirus infections, we disrupted its coding sequence in murine gammaherpesvirus-68 (MHV-68). MHV-68 lacking gL folded gH into a conformation antigenically distinct from the form that normally predominates on infected cells. gL-deficient virions bound less well than the wild type to epithelial cells and fibroblasts. However, they still incorporated gH and remained infectious. The cell-to-cell spread of gL-deficient viruses was remarkably normal, as was infection, dissemination, and latency establishment in vivo. Viral membrane fusion was therefore gL independent. The major function of gL appeared to be allowing gH to participate in cell binding prior to membrane fusion. This function was most important for the entry of MHV-68 virions into fibroblasts and epithelial cells.
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Affiliation(s)
- Laurent Gillet
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom
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38
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Lagos D, Trotter MWB, Vart RJ, Wang HW, Matthews NC, Hansen A, Flore O, Gotch F, Boshoff C. Kaposi sarcoma herpesvirus-encoded vFLIP and vIRF1 regulate antigen presentation in lymphatic endothelial cells. Blood 2006; 109:1550-8. [PMID: 17047149 DOI: 10.1182/blood-2006-05-024034] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) is etiologically linked to Kaposi sarcoma (KS), a tumor genetically akin to lymphatic endothelial cells (LECs). We obtained the immune transcriptional signature of KS and used KSHV-infected LECs (KLECs) as an in vitro model to determine the effects of KSHV on transcription and expression of genes involved in immunity. The antigen presentation, interferon (IFN) response, and cytokine transcriptomes of KLECs resemble those of KS. Transcription of genes involved in class I presentation is increased in KS and after infection of LECs, but MHC-I and ICAM-1 surface expression are down-regulated in KLECs. Inhibition of IFN induction of MHC-I transcription indicates that KSHV regulates MHC-I transcription. We show that MHC-I transcription is regulated by the KSHV-encoded viral FLICE inhibitory protein (vFLIP) and by viral IFN regulatory factor 1 (vIRF1). vFLIP up-regulates MHC-I and ICAM-1 through activation of NF-kappaB and stimulates T-cell proliferation, revealing a mechanism to prevent uncontrolled viral dissemination. In contrast, vIRF1 inhibits basal and IFN- and vFLIP-induced MHC-I transcription and surface expression through its interaction with the transcriptional coactivator p300, contributing to immune evasion. We propose that regulation of MHC-I by vFLIP and vIRF1 plays a crucial role in the host-pathogen equilibrium.
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Affiliation(s)
- Dimitrios Lagos
- Cancer Research United Kingdom Viral Oncology Group, Wolfson Institute for Biomedical Research, University College London, UK
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39
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Brambilla L, Tourlaki A, Ferrucci S, Brambati M, Boneschi V. Treatment of classic Kaposi's sarcoma-associated lymphedema with elastic stockings. J Dermatol 2006; 33:451-6. [PMID: 16848816 DOI: 10.1111/j.1346-8138.2006.00108.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Lymphedema of the lower extremities is a frequent complication of Kaposi's sarcoma (KS). Compressive therapy is the basis of treatment for lymphatic disorders, but to the authors' knowledge, there are no controlled trials to evaluate its effectiveness in KS-related lymphedema. Sixty-five patients with classic KS-associated lymphedema limited to below the knee were studied. Fifty patients received below-knee elastic stockings, whereas the remaining 15 did not use any compressive device. Among treated patients, 60% (30/50) experienced a limb volume reduction, while 40% (20/50) had an increase of limb volume. In contrast, all patients (15/15) of the untreated group had an increase of limb volume. No correlation between lymphedema reduction and systemic or local chemotherapy was observed, supporting compressive therapy as the major strategy for the treatment of this condition. Our results suggest that elastic stockings may be important tools for the management of lymphedema associated to classic KS.
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Affiliation(s)
- Lucia Brambilla
- Institute of Dermatological Sciences, University of Milan, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan, Italy
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40
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Bilello JP, Morgan JS, Damania B, Lang SM, Desrosiers RC. A genetic system for rhesus monkey rhadinovirus: use of recombinant virus to quantitate antibody-mediated neutralization. J Virol 2006; 80:1549-62. [PMID: 16415030 PMCID: PMC1346924 DOI: 10.1128/jvi.80.3.1549-1562.2006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Rhesus monkey rhadinovirus (RRV), a simian gamma-2 herpesvirus closely related to the Kaposi sarcoma-associated herpesvirus, replicates lytically in cultured rhesus monkey fibroblasts and establishes persistence in B cells. Overlapping cosmid clones were generated that encompass the entire 130-kilobase-pair genome of RRV strain 26-95, including the terminal repeat regions required for its replication. Cloned RRV that was produced by cotransfection of overlapping cosmids spanning the entire RRV26-95 genome replicated with growth kinetics and to titers similar to those of the parental, uncloned, wild-type RRV26-95. Expression cassettes for secreted-engineered alkaline phosphatase (SEAP) and green fluorescent protein (GFP) were inserted upstream of the R1 gene, and the cosmid-based system for RRV genome reconstitution was used to generate replication-competent, recombinant RRV that expressed either the SEAP or GFP reporter gene. Using the SEAP and GFP recombinant RRVs, assays were developed to monitor RRV infection, neutralization, and replication. Heat-inactivated sera from rhesus monkeys that were naturally or experimentally infected with RRV were assayed for their ability to neutralize RRV-SEAP and RRV-GFP infectivity using rhesus monkey fibroblasts. Sera from RRV-positive monkeys, but not RRV-negative monkeys, were consistently able to neutralize RRV infectivity when assayed by the production of SEAP activity or by the ability to express GFP. The neutralizing activity was present in the immunoglobulin fraction. Of the 17 rhesus monkeys tested, sera from rhesus monkey 26-95, i.e., the monkey that yielded the RRV 26-95 isolate, had the highest titer of neutralizing activity against RRV26-95. This cosmid-based genetic system and the reporter virus neutralization assay will facilitate study of the contribution of individual RRV glycoproteins to entry into different cell types, particularly fibroblasts and B cells.
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Affiliation(s)
- John P Bilello
- New England Primate Research Center/Harvard Medical School, One Pine Hill Drive, P.O. Box 9102, Southborough, MA 01772-9102, USA
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41
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Lehner PJ, Hoer S, Dodd R, Duncan LM. Downregulation of cell surface receptors by the K3 family of viral and cellular ubiquitin E3 ligases. Immunol Rev 2005; 207:112-25. [PMID: 16181331 DOI: 10.1111/j.0105-2896.2005.00314.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The mK3, K3, and K5 gene products from the gamma2 group of gamma-herpesviruses are the founding members of a family of membrane-associated ubiquitin E3 ligases. As part of the viral immunoevasion strategy, expression of these proteins results in a decrease in cell-surface major histocompatibility complex class I molecules and other immunoreceptors including intercellular adhesion molecule-1, CD86, and CD1d. These viral gene products all possess a characteristic cytosolic N-terminal RING-CH domain, responsible for ubiquitination of the target protein, and two membrane-spanning segments required for substrate specificity. For the majority of substrates, ubiquitination at the cell surface leads to rapid internalization and endolysosomal degradation, while mK3 ubiquitinates class I molecules associated with the peptide-loading complex resulting in proteasome-mediated degradation. Related viral genes with similar functions have been found in poxviruses, suggesting appropriation of these genes from the eukaryotic host. Ten membrane-associated RING-CH (MARCH) human genes with a similar organization have now been identified, and their overexpression leads to ubiquitination and downregulation of a variety of cell-surface immunoreceptors. While all the MARCH proteins are predicted to act as ubiquitin E3 ligases, their physiological role and substrates remain to be defined.
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Affiliation(s)
- Paul J Lehner
- Department of Medicine, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge, UK.
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42
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Raggo C, Ruhl R, McAllister S, Koon H, Dezube BJ, Früh K, Moses AV. Novel cellular genes essential for transformation of endothelial cells by Kaposi's sarcoma-associated herpesvirus. Cancer Res 2005; 65:5084-95. [PMID: 15958552 DOI: 10.1158/0008-5472.can-04-2822] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is involved in the development of lymphoproliferative diseases and Kaposi's sarcoma. The oncogenicity of this virus is reflected in vitro by its ability to transform B cells and endothelial cells. Infection of dermal microvascular endothelial cells (DMVEC) transforms the cells from a cobblestone-like monolayer to foci-forming spindle cells. This transformation is accompanied by dramatic changes in the cellular transcriptome. Known oncogenes, such as c-Kit, are among the KSHV-induced host genes. We previously showed that c-Kit is an essential cellular component of the KSHV-mediated transformation of DMVEC. Here, we test the hypothesis that the transformation process can be used to discover novel oncogenes. When expression of a panel of KSHV-induced cellular transcripts was inhibited with antisense oligomers, we observed inhibition of DMVEC proliferation and foci formation using antisense molecules to RDC1 and Neuritin. We further showed that transformation of KSHV-infected DMVEC was inhibited by small interfering RNA directed at RDC1 or Neuritin. Ectopic expression of Neuritin in NIH 3T3 cells resulted in changes in cell morphology and anchorage-independent growth, whereas RDC1 ectopic expression significantly increased cell proliferation. In addition, both RDC1- and Neuritin-expressing cells formed tumors in nude mice. RDC1 is an orphan G protein-coupled receptor, whereas Neuritin is a growth-promoting protein known to mediate neurite outgrowth. Neither gene has been previously implicated in tumorigenesis. Our data suggest that KSHV-mediated transformation involves exploitation of the hitherto unrealized oncogenic properties of RDC1 and Neuritin.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Cell Transformation, Viral/genetics
- DNA-Binding Proteins/biosynthesis
- DNA-Binding Proteins/genetics
- Endothelial Cells/cytology
- Endothelial Cells/virology
- GPI-Linked Proteins
- Gene Expression Profiling
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/physiology
- Humans
- LIM Domain Proteins
- Metalloproteins/biosynthesis
- Metalloproteins/genetics
- Mice
- Mice, Nude
- NIH 3T3 Cells
- Neuropeptides/biosynthesis
- Neuropeptides/genetics
- Oligonucleotide Array Sequence Analysis
- Oligonucleotides, Antisense/genetics
- Oncogenes/physiology
- Osteopontin
- Proto-Oncogene Proteins
- RNA, Small Interfering/genetics
- Receptors, CXCR
- Receptors, Chemokine/biosynthesis
- Receptors, Chemokine/genetics
- Receptors, G-Protein-Coupled/biosynthesis
- Receptors, G-Protein-Coupled/genetics
- Sarcoma, Kaposi/genetics
- Sarcoma, Kaposi/virology
- Sialoglycoproteins/biosynthesis
- Sialoglycoproteins/genetics
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Affiliation(s)
- Camilo Raggo
- Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon, USA
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Al Mehairi S, Cerasoli E, Sinclair AJ. Investigation of the multimerization region of the Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) protein K-bZIP: the proposed leucine zipper region encodes a multimerization domain with an unusual structure. J Virol 2005; 79:7905-10. [PMID: 15919946 PMCID: PMC1143620 DOI: 10.1128/jvi.79.12.7905-7910.2005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The K8 gene of Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) shares many functional similarities with the BZLF1 gene of Epstein-Barr virus. The protein products of K8 and BZLF1, K-bZIP (RAP, K8) and Zta (BZLF1, ZEBRA, Z) have both been proposed to be members of the bZIP family of transcription factors, forming multimers via a coiled-coil motif termed a leucine zipper. Substantial evidence supporting this model for Zta is published. Here, we demonstrate that the proposed leucine zipper region of K-bZIP (amino acids 182 to 218) is required for multimer formation but that it does not fold as a coiled coil.
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Affiliation(s)
- Salama Al Mehairi
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom
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Affiliation(s)
- Lauren Cheung
- Stanford Center for Lymphatic and Venous Disorders, Falk Cardiovascular Research Center, Stanford University School of Medicine, Stanford, California 94305, USA
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DeFilippis V, Früh K. Rhesus cytomegalovirus particles prevent activation of interferon regulatory factor 3. J Virol 2005; 79:6419-31. [PMID: 15858025 PMCID: PMC1091669 DOI: 10.1128/jvi.79.10.6419-6431.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
One of the most important innate host defense mechanisms against viral infection is the induction of interferon (IFN)-stimulated genes (ISGs). Immediately upon entry, viruses activate interferon-regulatory factor 3 (IRF3), as well as nuclear factor kappaB (NF-kappaB), which transactivate a subset of ISGs, proinflammatory genes, as well as IFN genes. Most large DNA viruses exhibit countermeasures against induction of this response. However, whereas human cytomegalovirus (HCMV) inhibits IFN-dependent induction of ISGs, IFN-independent induction of ISGs is observed both in the presence and, even moreso, in the absence of viral gene expression. Rhesus CMV (RhCMV) is an emerging animal model for HCMV sharing important similarities in primary structure, epidemiology, and pathogenesis. To determine whether RhCMV would similarly induce ISGs, we performed DNA microarray and quantitative PCR analysis of ISG expression in rhesus fibroblasts infected with RhCMV or HCMV. In contrast to HCMV, however, RhCMV did not induce expression of ISGs or proinflammatory genes at any time after infection. Moreover, dimerization and nuclear accumulation of IRF3, readily observed in HCMV-infected cells, was absent from RhCMV-infected cells, whereas neither virus seemed to activate NFkappaB. RhCMV also blocked IRF3 activation by live or UV-inactivated HCMV, suggesting that RhCMV inhibits viral IRF3 activation and the resultant ISG induction with extraordinary efficiency. Since infection during inhibition of protein expression by cycloheximide or inactivation of viral gene expression by UV treatment did not trigger IRF3 activation or ISG expression by RhCMV, we conclude that RhCMV virions contain a novel inhibitor of IFN-independent viral induction of ISG expression by IRF3.
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Affiliation(s)
- Victor DeFilippis
- Vaccine and Gene Therapy Institute, Oregon Health and Science University, 505 NW 185th Ave., Beaverton, OR 97006, USA
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Prakash O, Swamy OR, Peng X, Tang ZY, Li L, Larson JE, Cohen JC, Gill J, Farr G, Wang S, Samaniego F. Activation of Src kinase Lyn by the Kaposi sarcoma-associated herpesvirus K1 protein: implications for lymphomagenesis. Blood 2005; 105:3987-94. [PMID: 15665117 PMCID: PMC1895082 DOI: 10.1182/blood-2004-07-2781] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The K1 gene of Kaposi sarcoma-associated herpesvirus (KSHV) encodes a transmembrane glycoprotein bearing a functional immunoreceptor tyrosine-based activation motif (ITAM). Previously, we reported that the K1 protein induced plasmablastic lymphomas in K1 transgenic mice, and that these lymphomas showed enhanced Lyn kinase activity. Here, we report that systemic administration of the nuclear factor kappa B (NF-kappaB) inhibitor Bay 11-7085 or an anti-vascular endothelial growth factor (VEGF) antibody significantly reduced K1 lymphoma growth in nude mice. Furthermore, in KVL-1 cells, a cell line derived from a K1 lymphoma, inhibition of Lyn kinase activity by the Src kinase inhibitor PP2 decreased VEGF induction, NF-kappaB activity, and the cell proliferation index by 50% to 75%. In contrast, human B-cell lymphoma BJAB cells expressing K1, but not the ITAM sequence-deleted mutant K1, showed a marked increase in Lyn kinase activity with concomitant VEGF induction and NF-kappaB activation, indicating that ITAM sequences were required for the Lyn kinase-mediated activation of these factors. Our results suggested that K1-mediated constitutive Lyn kinase activation in K1 lymphoma cells is crucial for the production of VEGF and NF-kappaB activation, both strongly implicated in the development of KSHV-induced lymphoproliferative disorders.
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MESH Headings
- Animals
- Antibodies/immunology
- Cell Transformation, Neoplastic
- Cells, Cultured
- Enzyme Activation
- Gene Expression Regulation, Neoplastic
- Herpesvirus 8, Human
- Hyperplasia/genetics
- Hyperplasia/metabolism
- Hyperplasia/pathology
- Leukemia, B-Cell/genetics
- Leukemia, B-Cell/metabolism
- Leukemia, B-Cell/pathology
- Leukemia, B-Cell/virology
- Lymph Nodes/metabolism
- Lymph Nodes/pathology
- Mice
- Mice, Transgenic
- NF-kappa B/antagonists & inhibitors
- NF-kappa B/metabolism
- Promoter Regions, Genetic/genetics
- Protein Kinase Inhibitors/pharmacology
- Signal Transduction
- Vascular Endothelial Growth Factor A/antagonists & inhibitors
- Vascular Endothelial Growth Factor A/biosynthesis
- Vascular Endothelial Growth Factor A/immunology
- Vascular Endothelial Growth Factor A/metabolism
- Viral Proteins/genetics
- Viral Proteins/metabolism
- src-Family Kinases/antagonists & inhibitors
- src-Family Kinases/metabolism
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Affiliation(s)
- Om Prakash
- Laboratory of Molecular Oncology, Ochsner Clinic Foundation, 1516 Jefferson Highway, New Orleans, LA 70121, USA.
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Guasparri I, Keller SA, Cesarman E. KSHV vFLIP is essential for the survival of infected lymphoma cells. ACTA ACUST UNITED AC 2004; 199:993-1003. [PMID: 15067035 PMCID: PMC2211879 DOI: 10.1084/jem.20031467] [Citation(s) in RCA: 274] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Primary effusion lymphomas (PELs) associated with infection by the Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) have constitutive nuclear factor (NF)-kappaB activity that is essential for their survival, but the source of this activity is unknown. We report that viral FADD-like interleukin-1-beta-converting enzyme [FLICE/caspase 8]-inhibitory protein (FLIP) activates NF-kappaB more potently than cellular FLIP in B cells and that it is largely responsible for NF-kappaB activation in latently infected PEL cells. Elimination of vFLIP production in PEL cells by RNA interference results in significantly decreased NF-kappaB activity, down-regulation of essential NF-kappaB-regulated cellular prosurvival factors, induction of apoptosis, and enhanced sensitivity to external apoptotic stimuli. vFLIP is the first virally encoded gene shown to be essential for the survival of naturally infected tumor cells.
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Affiliation(s)
- Ilaria Guasparri
- Weill Medical College of Cornell University, New York, NY 10021, USA
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Sodhi A, Montaner S, Patel V, Gómez-Román JJ, Li Y, Sausville EA, Sawai ET, Gutkind JS. Akt plays a central role in sarcomagenesis induced by Kaposi's sarcoma herpesvirus-encoded G protein-coupled receptor. Proc Natl Acad Sci U S A 2004; 101:4821-6. [PMID: 15047889 PMCID: PMC387332 DOI: 10.1073/pnas.0400835101] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have recently engineered an in vivo endothelial cell-specific retroviral gene transfer system and found that a single Kaposi's sarcoma (KS)-associated herpesvirus/human herpesvirus 8 gene encoding a G protein-coupled receptor (vGPCR), is sufficient to induce KS-like tumors in mice. By using this system, we show here that the Akt signaling pathway plays a central role in vGPCR oncogenesis. Indeed, a constitutively active Akt was sufficient to induce benign hemangiomas in mice, whereas heterozyogosity for PTEN (the phosphatase and tension homologue deleted on chromosome 10), modestly enhancing basal Akt activity, dramatically enhanced vGPCR sarcomagenesis. Examination of KS biopsies from AIDS patients revealed active Akt as a prominent feature, supportive of a role for Akt in human Kaposi's sarcomagenesis. By using a vGPCR agonist-dependent mutant, we further establish constitutive activity as a requirement for vGPCR sarcomagenesis, validating targeted inhibition of key vGPCR signaling pathways as an approach for preventing its oncogenic potential. These observations prompted us to explore the efficacy of inhibiting Akt activation as a molecular approach to KS treatment. Pharmacological inhibition of the Akt pathway with the chemotherapeutic agent 7-hydroxystaurosporine prevented proliferation of vGPCR-expressing endothelial cells in vitro and inhibited their tumorigenic potential in vivo. Both were associated with a decrease in Akt activity. These results identify Akt as an essential player in vGPCR sarcomagenesis and demonstrate the therapeutic potential of drugs targeting this pathway in the treatment of KS.
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Affiliation(s)
- Akrit Sodhi
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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Milligan S, Robinson M, O'Donnell E, Blackbourn DJ. Inflammatory cytokines inhibit Kaposi's sarcoma-associated herpesvirus lytic gene transcription in in vitro-infected endothelial cells. J Virol 2004; 78:2591-6. [PMID: 14963163 PMCID: PMC369204 DOI: 10.1128/jvi.78.5.2591-2596.2004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The response of Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) to inflammatory cytokine treatment of experimentally infected endothelial cells was investigated. The cytokines inhibited spontaneous KSHV lytic gene expression but not the level of infection. The data suggest that if inflammatory cytokines present in KS lesions contribute to KSHV pathogenesis, they do so in part by promoting latent KSHV infection of the endothelial cells.
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Affiliation(s)
- Steven Milligan
- Division of Virology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 5JR, United Kingdom
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50
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Bartee E, Mansouri M, Hovey Nerenberg BT, Gouveia K, Früh K. Downregulation of major histocompatibility complex class I by human ubiquitin ligases related to viral immune evasion proteins. J Virol 2004; 78:1109-20. [PMID: 14722266 PMCID: PMC321412 DOI: 10.1128/jvi.78.3.1109-1120.2004] [Citation(s) in RCA: 250] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Poxviruses and gamma-2 herpesviruses share the K3 family of viral immune evasion proteins that inhibit the surface expression of glycoproteins such as major histocompatibility complex class I (MHC-I), B7.2, ICAM-1, and CD95(Fas). K3 family proteins contain an amino-terminal PHD/LAP or RING-CH domain followed by two transmembrane domains. To examine whether human homologues are functionally related to the viral immunoevasins, we studied seven membrane-associated RING-CH (MARCH) proteins. All MARCH proteins located to subcellular membranes, and several MARCH proteins reduced surface levels of known substrates of the viral K3 family. Two closely related proteins, MARCH-IV and MARCH-IX, reduced surface expression of MHC-I molecules. In the presence of MARCH-IV or MARCH-IX, MHC-I was ubiquitinated and rapidly internalized by endocytosis, whereas MHC-I molecules lacking lysines in their cytoplasmic tail were resistant to downregulation. The amino-terminal regions containing the RING-CH domain of several MARCH proteins examined catalyzed multiubiquitin formation in vitro, suggesting that MARCH proteins are ubiquitin ligases. The functional similarity of the MARCH family and the K3 family suggests that the viral immune evasion proteins were derived from MARCH proteins, a novel family of transmembrane ubiquitin ligases that seems to target glycoproteins for lysosomal destruction via ubiquitination of the cytoplasmic tail.
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Affiliation(s)
- Eric Bartee
- Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, USA
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