scholarly journals Effects of the NEDD8-Activating Enzyme Inhibitor MLN4924 on Lytic Reactivation of Kaposi's Sarcoma-Associated Herpesvirus

2017 ◽  
Vol 91 (19) ◽  
Author(s):  
Pey-Jium Chang ◽  
Lee-Wen Chen ◽  
Li-Yu Chen ◽  
Chien-Hui Hung ◽  
Ying-Ju Shih ◽  
...  
Keyword(s):  
Transcriptional Regulation ◽  
Cell Lines ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Lytic Cycle ◽  
Viral Reactivation ◽  
Lytic Reactivation ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT The switch of Kaposi's sarcoma-associated herpesvirus (KSHV) from latency to lytic replication is a key event for viral dissemination and pathogenesis. MLN4924, a novel neddylation inhibitor, reportedly causes the onset of KSHV reactivation but impairs later phases of the viral lytic program in infected cells. Thus far, the molecular mechanism involved in the modulation of the KSHV lytic cycle by MLN4924 is not yet fully understood. Here, we confirmed that treatment of different KSHV-infected primary effusion lymphoma (PEL) cell lines with MLN4924 substantially induces viral lytic protein expression. Due to the key role of the virally encoded ORF50 protein in the latent-to-lytic switch, we investigated its transcriptional regulation by MLN4924. We found that MLN4924 activates the ORF50 promoter (ORF50p) in KSHV-positive cells (but not in KSHV-negative cells), and the RBP-Jκ-binding elements within the promoter are critically required for MLN4924 responsiveness. In KSHV-negative cells, reactivation of the ORF50 promoter by MLN4924 requires the presence of the latency-associated nuclear antigen (LANA). Under such a condition, LANA acts as a repressor to block the ORF50p activity, whereas MLN4924 treatment relieves LANA-mediated repression. Importantly, we showed that LANA is a neddylated protein and can be deneddylated by MLN4924. On the other hand, we revealed that MLN4924 exhibits concentration-dependent biphasic effects on 12-O-tetradecanoylphorbol-13-acetate (TPA)- or sodium butyrate (SB)-induced viral reactivation in PEL cell lines. In other words, low concentrations of MLN4924 promote activation of TPA- or SB-mediated viral reactivation, whereas high concentrations of MLN4924, conversely, inhibit the progression of TPA- or SB-mediated viral lytic program. IMPORTANCE MLN4924 is a neddylation (NEDD8 modification) inhibitor, which currently acts as an anti-cancer drug in clinical trials. Although MLN4924 has been reported to trigger KSHV reactivation, many aspects regarding the action of MLN4924 in regulating the KSHV lytic cycle are not fully understood. Since the KSHV ORF50 protein is the key regulator of viral lytic reactivation, we focus on its transcriptional regulation by MLN4924. We here show that activation of the ORF50 gene by MLN4924 involves the relief of LANA-mediated transcriptional repression. Importantly, we find that LANA is a neddylated protein. To our knowledge, this is the first report showing that neddylation occurs in viral proteins. Additionally, we provide evidence that different concentrations of MLN4924 have opposite effects on TPA-mediated or SB-mediated KSHV lytic cycle activation. Therefore, in clinical application, we propose that MLN4924 needs to be used with caution in combination therapy to treat KSHV-positive subjects.

scholarly journals Nuclear Innate Immune DNA Sensor IFI16 Is Degraded during Lytic Reactivation of Kaposi's Sarcoma-Associated Herpesvirus (KSHV): Role of IFI16 in Maintenance of KSHV Latency

2016 ◽  
Vol 90 (19) ◽  
pp. 8822-8841 ◽  
Author(s):  
Arunava Roy ◽  
Dipanjan Dutta ◽  
Jawed Iqbal ◽  
Gina Pisano ◽  
Olsi Gjyshi ◽  
...  
Keyword(s):  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Innate Immune ◽  
Lytic Cycle ◽  
Lytic Gene ◽  
Lytic Reactivation ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACTIFI16 (interferon gamma-inducible protein 16) recognizes nuclear episomal herpesvirus (Kaposi's sarcoma-associated herpesvirus [KSHV], Epstein-Barr virus [EBV], and herpes simplex virus 1 [HSV-1]) genomes and induces the inflammasome and interferon beta responses. It also acts as a lytic replication restriction factor and inhibits viral DNA replication (human cytomegalovirus [HCMV] and human papillomavirus [HPV]) and transcription (HSV-1, HCMV, and HPV) through epigenetic modifications of the viral genomes. To date, the role of IFI16 in the biology of latent viruses is not known. Here, we demonstrate that knockdown of IFI16 in the latently KSHV-infected B-lymphoma BCBL-1 and BC-3 cell lines results in lytic reactivation and increases in levels of KSHV lytic transcripts, proteins, and viral genome replication. Similar results were also observed during KSHV lytic cycle induction in TREX-BCBL-1 cells with the doxycycline-inducible lytic cycle switch replication and transcription activator (RTA) gene. Overexpression of IFI16 reduced lytic gene induction by the chemical agent 12-O-tetradecoylphorbol-13-acetate (TPA). IFI16 protein levels were significantly reduced or absent in TPA- or doxycycline-induced cells expressing lytic KSHV proteins. IFI16 is polyubiquitinated and degraded via the proteasomal pathway. The degradation of IFI16 was absent in phosphonoacetic acid-treated cells, which blocks KSHV DNA replication and, consequently, late lytic gene expression. Chromatin immunoprecipitation assays of BCBL-1 and BC-3 cells demonstrated that IFI16 binds to KSHV gene promoters. Uninfected epithelial SLK and osteosarcoma U2OS cells transfected with KSHV luciferase promoter constructs confirmed that IFI16 functions as a transcriptional repressor. These results reveal that KSHV utilizes the innate immune nuclear DNA sensor IFI16 to maintain its latency and repression of lytic transcripts, and a late lytic KSHV gene product(s) targets IFI16 for degradation during lytic reactivation.IMPORTANCELike all herpesviruses, latency is an integral part of the life cycle of Kaposi's sarcoma-associated herpesvirus (KSHV), an etiological agent for many human cancers. Herpesviruses utilize viral and host factors to successfully evade the host immune system to maintain latency. Reactivation is a complex event where the latent episomal viral genome springs back to active transcription of lytic cycle genes. Our studies reveal that KSHV has evolved to utilize the innate immune sensor IFI16 to keep lytic cycle transcription in dormancy. We demonstrate that IFI16 binds to the lytic gene promoter, acts as a transcriptional repressor, and thereby helps to maintain latency. We also discovered that during the late stage of lytic replication, KSHV selectively degrades IFI16, thus relieving transcriptional repression. This is the first report to demonstrate the role of IFI16 in latency maintenance of a herpesvirus, and further understanding will lead to the development of strategies to eliminate latent infection.

scholarly journals Lytic Replication-Defective Kaposi's Sarcoma-Associated Herpesvirus: Potential Role in Infection and Malignant Transformation

2004 ◽  
Vol 78 (20) ◽  
pp. 11108-11120 ◽  
Author(s):  
Jian-Hong Deng ◽  
Yan-Jin Zhang ◽  
Xin-Ping Wang ◽  
Shou-Jiang Gao
Keyword(s):  
Malignant Transformation ◽  
Cell Lines ◽  
Kaposi's Sarcoma ◽  
Potential Role ◽  
Primary Effusion Lymphoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Screening Methods ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Defective viruses often have pivotal roles in virus-induced diseases. Although Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically associated with Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL), defective KSHV has not been reported. Using differential genetic screening methods, we show that defective KSHV is present in KS tumors and PEL cell lines. To investigate the role of defective viruses in KSHV-induced pathogenesis, we isolated and characterized a lytic replication-defective KSHV, KV-1, containing an 82-kb genomic deletion of solely lytic genes. Cells harboring KV-1 escaped G0/G1 apoptosis induced by spontaneous lytic replication occurred in cells infected with regular KSHV but maintained efficient latent replication. Consequently, KV-1-infected cells had phenotypes of enhanced cell proliferation and transformation potentials. Importantly, KV-1 was packaged as infectious virions by using regular KSHV as helpers, and KV-1-like variants were detected in cultures of two of five KSHV cell lines and 1 of 18 KS tumors. These results point to a potential role for defective viruses in the regulation of KSHV infection and malignant transformation.

scholarly journals Suppression of Tetradecanoyl Phorbol Acetate-Induced Lytic Reactivation of Kaposi's Sarcoma-Associated Herpesvirus by K1 Signal Transduction

2002 ◽  
Vol 76 (23) ◽  
pp. 12185-12199 ◽  
Author(s):  
Bok-Soo Lee ◽  
Mini Paulose-Murphy ◽  
Young-Hwa Chung ◽  
Michelle Connlole ◽  
Steven Zeichner ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Kaposi's Sarcoma ◽  
Ectopic Expression ◽  
Kaposi’S Sarcoma ◽  
Viral Reactivation ◽  
Dependent Manner ◽  
Tetradecanoyl Phorbol Acetate ◽  
Lytic Reactivation ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT The K1 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) contains an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic region and elicits cellular signal transduction through this motif. To investigate the role of K1 signal transduction in KSHV replication, we expressed full-length K1 and CD8-K1 chimeras in BCBL1 cells. Unlike its strong signaling activity in uninfected B lymphocytes, K1 did not induce intracellular calcium mobilization or NF-AT activation at detectable levels in KSHV-infected BCBL1 cells. Instead, K1 signaling dramatically suppressed KSHV lytic reactivation induced by tetradecanoyl phorbol acetate (TPA) stimulation, but not by ORF50 ectopic expression. Mutational analysis showed that the cytoplasmic ITAM sequence of K1 was required for this suppression. Viral microarray and immunoblot analyses demonstrated that K1 signaling suppressed the TPA-mediated increase in the expression of a large subset of viral lytic genes in KSHV-infected BCBL1 cells. Furthermore, electrophoretic mobility shift assays demonstrated that TPA-induced activation of AP-1, NF-κB, and Oct-1 activities was severely diminished in BCBL1 cells expressing the K1 cytoplasmic domain. The reduced activities of these transcription factors may confer the observed reduction in viral lytic gene expression. These results demonstrate that K1-mediated signal transduction in KSHV-infected cells is profoundly different from that in KSHV-negative cells. Furthermore, K1 signal transduction efficiently suppresses TPA-mediated viral reactivation in an ITAM-dependent manner, and this suppression may contribute to the establishment and/or maintenance of KSHV latency in vivo.

scholarly journals Activation of Kaposi's Sarcoma-Associated Herpesvirus (Human Herpesvirus 8) Lytic Replication by Human Cytomegalovirus

2001 ◽  
Vol 75 (3) ◽  
pp. 1378-1386 ◽  
Author(s):  
Jeffrey Vieira ◽  
Patricia O'Hearn ◽  
Louise Kimball ◽  
Bala Chandran ◽  
Lawrence Corey
Keyword(s):  
Human Cytomegalovirus ◽  
Kaposi's Sarcoma ◽  
Human Fibroblasts ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Lytic Cycle ◽  
Nuclear Antigen ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT The majority of Kaposi's sarcoma-associated herpesvirus (KSHV)-infected cells identified in vivo contain latent KSHV, with lytic replication in only a few percent of cells, as is the case for the cells of Kaposi's sarcoma (KS) lesions. Factors that influence KSHV latent or lytic replication are not well defined. Because persons with KS are often immunosuppressed and susceptible to many infectious agents, including human cytomegalovirus (HCMV), we have investigated the potential for HCMV to influence the replication of KSHV. Important to this work was the construction of a recombinant KSHV, rKSHV.152, expressing the green fluorescent protein (GFP) andneo (conferring resistance to G418). The expression of GFP was a marker of KSHV infection in cells of both epithelial and endothelial origin. The rKSHV.152 virus was used to establish cells, including human fibroblasts (HF), containing only latent KSHV, as demonstrated by latency-associated nuclear antigen expression and Gardella gel analysis. HCMV infection of KSHV latently infected HF activated KSHV lytic replication with the production of infectious KSHV. Dual-color immunofluorescence detected both the KSHV lytic open reading frame 59 protein and the HCMV glycoprotein B in coinfected cells, and UV-inactivated HCMV did not activate the production of infectious KSHV-GFP. In addition, HCMV coinfection increased the production of KSHV from endothelial cells and activated lytic cycle gene expression in keratinocytes. These data demonstrate that HCMV can activate KSHV lytic replication and suggest that HCMV could influence KSHV pathogenesis.

scholarly journals ORF33 and ORF38 of Kaposi's Sarcoma-Associated Herpesvirus Interact and Are Required for Optimal Production of Infectious Progeny Viruses

2015 ◽  
Vol 90 (4) ◽  
pp. 1741-1756 ◽  
Author(s):  
Jian-jun Wu ◽  
Denis Avey ◽  
Wenwei Li ◽  
Joseph Gillen ◽  
Bishi Fu ◽  
...  
Keyword(s):  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Lytic Cycle ◽  
Viral Gene ◽  
Virus Propagation ◽  
Progeny Virion ◽  
Cytoplasmic Vesicles ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACTWe recently showed that the interaction between Kaposi's sarcoma-associated herpesvirus (KSHV) tegument proteins ORF33 and ORF45 is crucial for progeny virion production, but the exact functions of KSHV ORF33 during lytic replication were unknown (J. Gillen, W. Li, Q. Liang, D. Avey, J. Wu, F. Wu, J. Myoung, and F. Zhu, J Virol89:4918–4931, 2015,http://dx.doi.org/10.1128/JVI.02925-14). Therefore, here we investigated the relationship between ORF33 and ORF38, whose counterparts in both alpha- and betaherpesviruses interact with each other. Using specific monoclonal antibodies, we found that both proteins are expressed during the late lytic cycle with similar kinetics and that both are present in mature virions as components of the tegument. Furthermore, we confirmed that ORF33 interacts with ORF38. Interestingly, we observed that ORF33 tightly associates with the capsid, whereas ORF38 associates with the envelope. We generated ORF33-null, ORF38-null, and double-null mutants and found that these mutants apparently have identical phenotypes: the mutations caused no apparent effect on viral gene expression but reduced the yield of progeny virion by about 10-fold. The progeny virions also lack certain virion component proteins, including ORF45. During viral lytic replication, the virions associate with cytoplasmic vesicles. We also observed that ORF38 associates with the membranes of vesicles and colocalizes with the Golgi membrane or early endosome membrane. Further analyses of ORF33/ORF38 mutants revealed the reduced production of virion-containing vesicles, suggesting that ORF33 and ORF38 are involved in the transport of newly assembled viral particles into cytoplasmic vesicles, a process important for viral maturation and egress.IMPORTANCEHerpesvirus assembly is an essential step in virus propagation that leads to the generation of progeny virions. It is a complicated process that depends on the delicate regulation of interactions among virion proteins. We previously revealed an essential role of ORF45-ORF33 binding for virus assembly. Here, we report that ORF33 and its binding partner, ORF38, are required for infectious virus production due to their important role in the tegumentation process. Moreover, we found that both ORF33 and ORF38 are involved in the transportation of virions through vesicles during maturation and egress. Our results provide new insights into the important roles of ORF33 and ORF38 during viral assembly, a process critical for virus propagation that is intimately linked to KSHV pathobiology.

scholarly journals Principal Role of TRAP/Mediator and SWI/SNF Complexes in Kaposi's Sarcoma-Associated Herpesvirus RTA-Mediated Lytic Reactivation

2003 ◽  
Vol 23 (6) ◽  
pp. 2055-2067 ◽  
Author(s):  
Yousang Gwack ◽  
Hwa Jin Baek ◽  
Hiroyuki Nakamura ◽  
Sun Hwa Lee ◽  
Michael Meisterernst ◽  
...  
Keyword(s):  
Gene Expression ◽  
Kaposi's Sarcoma ◽  
Viral Gene Expression ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Viral Gene ◽  
Transcription Activator ◽  
Lytic Reactivation ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT An important step in the herpesvirus life cycle is the switch from latency to lytic reactivation. The RTA transcription activator of Kaposi's sarcoma-associated herpesvirus (KSHV) acts as a molecular switch for lytic reactivation. Here we demonstrate that KSHV RTA recruits CBP, the SWI/SNF chromatin remodeling complex, and the TRAP/Mediator coactivator into viral promoters through interactions with a short acidic sequence in the carboxyl region and that this recruitment is essential for RTA-dependent viral gene expression. The Brg1 subunit of SWI/SNF and the TRAP230 subunit of TRAP/Mediator were shown to interact directly with RTA. Consequently, genetic ablation of these interactions abolished KSHV lytic replication. These results demonstrate that the recruitment of CBP, SWI/SNF, and TRAP/Mediator complexes by RTA is the principal mechanism to direct well-controlled viral gene expression and thereby viral lytic reactivation.

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus Transactivator RTA Promotes Degradation of the Repressors To Regulate Viral Lytic Replication

2008 ◽  
Vol 82 (7) ◽  
pp. 3590-3603 ◽  
Author(s):  
Zhilong Yang ◽  
Zhangcai Yan ◽  
Charles Wood
Keyword(s):  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Viral Reactivation ◽  
Common Mechanism ◽  
Ubiquitin Proteasome Pathway ◽  
Ubiquitin Proteasome ◽  
Proteasome Pathway ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) RTA is an important protein involved in the induction of KSHV lytic replication from latency through activation of the lytic cascade. A number of cellular and viral proteins, including K-RBP, have been found to repress RTA-mediated transactivation and KSHV lytic replication. However, it is unclear as to how RTA overcomes the suppression during lytic reactivation. In this study, we found that RTA can induce K-RBP degradation through the ubiquitin-proteasome pathway and that two regions in RTA are responsible. Moreover, we found that RTA can promote the degradation of several other RTA repressors. RTA mutants that are defective in inducing K-RBP degradation cannot activate RTA responsive promoter as efficiently as wild-type RTA. Interference of the ubiquitin-proteasome pathway affected RTA-mediated transactivation and KSHV reactivation from latency. Our results suggest that KSHV RTA can stimulate the turnover of repressors to modulate viral reactivation. Since herpes simplex virus type 1 transactivator ICP0 and human cytomegalovirus transactivator pp71 also stimulate the degradation of cellular silencers, it is possible that the promotion of silencer degradation by viral transactivators may be a common mechanism for regulating the lytic replication of herpesviruses.

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus Lytic Switch Protein Stimulates DNA Binding of RBP-Jk/CSL To Activate the Notch Pathway

2006 ◽  
Vol 80 (19) ◽  
pp. 9697-9709 ◽  
Author(s):  
Kyla Driscoll Carroll ◽  
Wei Bu ◽  
Diana Palmeri ◽  
Sophia Spadavecchia ◽  
Stephen J. Lynch ◽  
...  
Keyword(s):  
Dna Binding ◽  
Transcriptional Activation ◽  
Kaposi's Sarcoma ◽  
Notch Pathway ◽  
Kaposi’S Sarcoma ◽  
Lytic Cycle ◽  
Viral Reactivation ◽  
Transactivation Domain ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) lytic switch protein, Rta, is a ligand-independent inducer of the Notch signal transduction pathway, and KSHV cannot reactivate from latency in cells null for the Notch target protein RBP-Jk. Here we show that Rta promotes DNA binding of RBP-Jk, a mechanism that is fundamentally different from that established for the RBP-Jk-activating proteins, Notch intracellular domain (NICD) and Epstein-Barr virus EBNA2. Although constitutively active RBP-Jk and NICD do not transactivate KSHV promoters independently, cotransfection of an Rta mutant lacking its transactivation domain robustly restores transcriptional activation. Cooperation requires intact DNA binding sites for Rta and RBP-Jk and trimeric complex formation between the three molecules in vitro. In infected cells, RBP-Jk is virtually undetectable on a series of viral and cellular promoters during KSHV latency but is significantly enriched following Rta expression during viral reactivation. Accordingly, Rta, but not EBNA2 and NICD, reactivates the complete viral lytic cycle.

scholarly journals The FAT10 Posttranslational Modification Is Involved in Lytic Replication of Kaposi’s Sarcoma-Associated Herpesvirus

2021 ◽  
Vol 95 (10) ◽  
Author(s):  
Atsuko Sugimoto ◽  
Yuichi Abe ◽  
Tadashi Watanabe ◽  
Kohei Hosokawa ◽  
Jun Adachi ◽  
...  
Keyword(s):  
Protein Expression ◽  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Kaposi's Sarcoma ◽  
Virus Production ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Lytic Cycle ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT During Kaposi’s sarcoma-associated herpesvirus (KSHV) lytic replication, host cell functions, including protein expression and posttranslational modification pathways, are dysregulated by KSHV to promote virus production. Here, we attempted to identify key proteins for KSHV lytic replication by profiling protein expression in the latent and lytic phases using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Proteomic analysis, immunoblotting, and quantitative PCR demonstrated that antigen F (HLA-F) adjacent transcript 10 (FAT10) and UBE1L2 (also known as ubiquitin-like modifier-activating enzyme 6 [UBA6]) were upregulated during lytic replication. FAT10 is a ubiquitin-like protein (UBL). UBE1L2 is the FAT10-activating enzyme (E1), which is essential for FAT10 modification (FAT10ylation). FAT10ylated proteins were immediately expressed after lytic induction and increased over time during lytic replication. Knockout of UBE1L2 suppressed KSHV production but not KSHV DNA synthesis. In order to isolate FAT10ylated proteins during KSHV lytic replication, we conducted immunoprecipitation using anti-FAT10 antibody and nickel-nitrilotriacetic acid (Ni-NTA) chromatography of exogenously expressed His-tagged FAT10 from cells undergoing latent or lytic replication. LC-MS/MS was performed to identify FAT10ylated proteins. We identified KSHV ORF59 and ORF61 as FAT10ylation substrates. Our study revealed that the UBE1L2-FAT10 system is upregulated during KSHV lytic replication, and it contributes to viral propagation. IMPORTANCE Ubiquitin and UBL posttranslational modifications, including FAT10, are utilized and dysregulated by viruses for achievement of effective infection and virion production. The UBE1L2-FAT10 system catalyzes FAT10ylation, where one or more FAT10 molecules are covalently linked to a substrate. FAT10ylation is catalyzed by the sequential actions of E1 (activation enzyme), E2 (conjugation enzyme), and E3 (ligase) enzymes. The E1 enzyme for FAT10ylation is UBE1L2, which activates FAT10 and transfers it to E2/USE1. FAT10ylation regulates the cell cycle, interferon (IFN) signaling, and protein degradation; however, its primary biological function remains unknown. Here, we revealed that KSHV lytic replication induces UBE1L2 expression and production of FAT10ylated proteins, including KSHV lytic proteins. Moreover, UBE1L2 knockout suppressed virus production during the lytic cycle. This is the first report demonstrating the contribution of the UBE1L2-FAT10 system to KSHV lytic replication. Our findings provide insight into the physiological function(s) of novel posttranslational modifications in KSHV lytic replication.

scholarly journals Host Range of Kaposi's Sarcoma-Associated Herpesvirus in Cultured Cells

2003 ◽  
Vol 77 (11) ◽  
pp. 6474-6481 ◽  
Author(s):  
Jill T. Bechtel ◽  
Yuying Liang ◽  
Joshua Hvidding ◽  
Don Ganem
Keyword(s):  
Host Range ◽  
Cell Lines ◽  
Kaposi's Sarcoma ◽  
Latent Infection ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Serial Transfer ◽  
Latently Infected ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Difficulties in efficiently propagating Kaposi's sarcoma-associated herpesvirus (KSHV) in culture have generated the impression that the virus displays a narrow host range. Here we show that, contrary to expectation, KSHV can establish latent infection in many adherent cell lines, including human and nonhuman cells of epithelial, endothelial, and mesenchymal origin. (Paradoxically, the only lines in which we have not observed successful latent infection are cultured lymphoma cell lines.) In most latently infected lines, spontaneous lytic replication is rare and (with only two exceptions) is not efficiently induced by phorbol ester treatment—a result that explains the failure of most earlier studies to observe efficient serial transfer of infection. However, ectopic expression of the KSHV lytic switch protein RTA from an adenoviral vector leads to the prompt induction of lytic replication in all latently infected lines, with the production of infectious KSHV virions. These results indicate (i) that the host cell receptor(s) and entry machinery for KSHV are widely distributed on cultured adherent cells, (ii) that latency is the default pathway of infection, and (iii) that blocks to lytic induction are frequent and largely reside at or upstream of the expression of KSHV RTA.

Sign in / Sign up

Export Citation Format

Share Document