scholarly journals Oncogenic herpesvirus engages the endothelial transcription factors SOX18 and PROX1 to increase viral genome copies and virus production

2019 ◽  
Author(s):  
Silvia Gramolelli ◽  
Endrit Elbasani ◽  
Veijo Nurminen ◽  
Krista Tuohinto ◽  
Thomas Günther ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Viral Genome ◽  
Kaposi Sarcoma ◽  
Virus Production ◽  
Lytic Replication ◽  
Therapeutic Modality ◽  
Lytic Gene ◽  
Kshv Infection ◽  
Lytic Gene Expression

ABSTRACTKaposi sarcoma (KS) is a tumour of endothelial origin caused by KS herpesvirus (KSHV) infection and suggested to originate from lymphatic endothelial cells (LECs). While KSHV establishes latency in virtually all susceptible cell types, LECs support a spontaneous lytic gene expression program with high viral genome copies and release of infectious virus. Here, we investigated the role of PROX1, SOX18 and COUPTF2, drivers of lymphatic endothelial fate during embryogenesis, in this unique KSHV infection program. We found that these factors were co-expressed in KS tumours with the viral lytic marker K8.1, and that SOX18 and PROX1 regulate KSHV infection via two independent mechanisms. SOX18 binds to the viral origins of replication and its depletion or chemical inhibition significantly reduced the KSHV genome copies in LECs. PROX1 interacts with ORF50, the initiator of the lytic cascade, increases lytic gene expression and virus production and its depletion reduces KSHV spontaneous lytic reactivation. Upon lytic replication, PROX1 binds to the KSHV genome in the promoter region of ORF50 and enhances its transactivation activity. These results demonstrate the importance of two endothelial transcription factors in the regulation of the KSHV life cycle and introduce SOX18 inhibition as a potential, novel therapeutic modality for KS.

scholarly journals Caspase-7 Cleavage of Kaposi Sarcoma-associated Herpesvirus ORF57 Confers a Cellular Function against Viral Lytic Gene Expression

2010 ◽  
Vol 285 (15) ◽  
pp. 11297-11307 ◽  
Author(s):  
Vladimir Majerciak ◽  
Michael Kruhlak ◽  
Pradeep K. Dagur ◽  
J. Philip McCoy ◽  
Zhi-Ming Zheng
Keyword(s):  
Gene Expression ◽  
Kaposi Sarcoma ◽  
Cellular Function ◽  
Lytic Gene ◽  
Lytic Gene Expression ◽  
Caspase 7

scholarly journals New Noncoding Lytic Transcripts Derived from the Epstein-Barr Virus Latency Origin of Replication,oriP, Are Hyperedited, Bind the Paraspeckle Protein, NONO/p54nrb, and Support Viral Lytic Transcription

2015 ◽  
Vol 89 (14) ◽  
pp. 7120-7132 ◽  
Author(s):  
Subing Cao ◽  
Walter Moss ◽  
Tina O'Grady ◽  
Monica Concha ◽  
Michael J. Strong ◽  
...  
Keyword(s):  
Gene Expression ◽  
Epstein Barr Virus ◽  
Noncoding Rnas ◽  
Lytic Replication ◽  
Long Noncoding Rnas ◽  
Origin Of Replication ◽  
Lytic Gene ◽  
Barr Virus ◽  
Lytic Gene Expression ◽  
Epstein Barr

ABSTRACTWe have previously shown that the Epstein-Barr virus (EBV) likely encodes hundreds of viral long noncoding RNAs (vlncRNAs) that are expressed during reactivation. Here we show that the EBV latency origin of replication (oriP) is transcribed bi-directionally during reactivation and that both leftward (oriPtLs) and rightward (oriPtRs) transcripts are largely localized in the nucleus. While the oriPtLs are most likely noncoding, at least some of the oriPtRs contain the BCRF1/vIL10 open reading frame. Nonetheless, oriPtR transcripts with long 5′ untranslated regions may partially serve noncoding functions. Both oriPtL and oriPtR transcripts are expressed with late kinetics, and their expression is inhibited by phosphonoacetic acid. RNA sequencing (RNA-seq) analysis showed that oriPtLs and oriPtRs exhibited extensive “hyperediting” at their Family of Repeat (FR) regions. RNA secondary structure prediction revealed that the FR region of both oriPtLs and oriPtRs may form large evolutionarily conserved and thermodynamically stable hairpins. The double-stranded RNA-binding protein and RNA-editing enzyme ADAR was found to bind to oriPtLs, likely facilitating editing of the FR hairpin. Further, the multifunctional paraspeckle protein, NONO, was found to bind to oriPt transcripts, suggesting that oriPts interact with the paraspeckle-based innate antiviral immune pathway. Knockdown and ectopic expression of oriPtLs showed that it contributes to global viral lytic gene expression and viral DNA replication. Together, these results show that these new vlncRNAs interact with cellular innate immune pathways and that they help facilitate progression of the viral lytic cascade.IMPORTANCERecent studies have revealed that the complexity of lytic herpesviral transcriptomes is significantly greater than previously appreciated with hundreds of viral long noncoding RNAs (vlncRNAs) being recently discovered. Work on cellular lncRNAs over the past several years has just begun to give us an initial appreciation for the array of functions they play in complex formation and regulatory processes in the cell. The newly identified herpesvirus lncRNAs are similarly likely to play a variety of different functions, although these functions are likely tailored to specific needs of the viral infection cycles. Here we describe novel transcripts derived from the EBV latency origin of replication. We show that they are hyperedited, that they interact with a relatively newly appreciated antiviral pathway, and that they play a role in facilitating viral lytic gene expression. These investigations are a starting point to unraveling the complex arena of vlncRNA function in herpesvirus lytic replication.

scholarly journals Concurrent Expression of Latent and a Limited Number of Lytic Genes with Immune Modulation and Antiapoptotic Function by Kaposi's Sarcoma-Associated Herpesvirus Early during Infection of Primary Endothelial and Fibroblast Cells and Subsequent Decline of Lytic Gene Expression

2004 ◽  
Vol 78 (7) ◽  
pp. 3601-3620 ◽  
Author(s):  
Harinivas H. Krishnan ◽  
Pramod P. Naranatt ◽  
Marilyn S. Smith ◽  
Ling Zeng ◽  
Clark Bloomer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Immune Modulation ◽  
Kaposi's Sarcoma ◽  
Lytic Cycle ◽  
Lytic Gene ◽  
Kshv Infection ◽  
Lytic Gene Expression ◽  
Genome Array ◽  
Lytic Genes

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) infection of in vitro target cells is characterized by the expression of the latency-associated open reading frame (ORF) 73 gene (LANA-1) and the absence of progeny virus production. This default latent infection can be switched into lytic cycle by phorbol ester and by the lytic cycle ORF 50 (RTA) protein. In this study, the kinetics of latent and lytic gene expression immediately following KSHV infection of primary human dermal microvascular endothelial (HMVEC-d) and foreskin fibroblast (HFF) cells were examined by real-time reverse transcriptase PCR and whole-genome array. Within 2 h postinfection (p.i.), high levels of ORF 50 transcripts were detected in both cell types, which declined sharply by 24 h p.i. In contrast, comparatively low levels of ORF 73 expression were detected within 2 h p.i., increased subsequently, were maintained at a steady state, and declined slowly by 120 h p.i. The RTA and LANA-1 proteins were detected in the majority of infected cells by immunoperoxidase assays. In genome array, only 29 of 94 (31%) KSHV genes were expressed, which included 11 immediate-early/early, 8 early, and 5 late lytic genes and 4 latency-associated genes. While the expression of latent ORF 72, 73, and K13 genes continued, nearly all of the lytic genes declined or were undetectable by 8 and 24 h p.i. in HMVEC-d and HFF cells, respectively. Only a limited number of RTA-activated KSHV genes were expressed briefly, and the majority of KSHV genes involved in viral DNA synthesis and structural proteins were not expressed. However, early during infection, the lytic K2, K4, K5, K6, and vIRF2 genes with immune modulation functions and the K7 gene with antiapoptotic function were expressed. Expression of K5 was detected for up to 5 days of observation, and vIRF2 was expressed up to 24 h p.i. The full complement of lytic cycle genes were expressed when 12-O-tetradecanoylphorbol-13-acetate was added to the HMVEC-d cells after 48 h p.i. These data suggest that in contrast to alpha- and betaherpesviruses and some members of gammaherpesviruses, gamma-2 KSHV in vitro infection is characterized by the concurrent expression of latent and a limited number of lytic genes immediately following infection and a subsequent decline and/or absence of lytic gene expression with the persistence of latent genes. Expression of its limited lytic cycle genes could be a “strategy” that evolved in KSHV allowing it to evade the immune system and to provide the necessary factors and time to establish and/or maintain latency during the initial phases of infection. These are unique observations among in vitro herpesvirus infections and may have important implications in KSHV biology and pathogenesis.

scholarly journals Persistent KSHV Infection Increases EBV-Associated Tumor Formation In Vivo via Enhanced EBV Lytic Gene Expression

2017 ◽  
Vol 22 (1) ◽  
pp. 61-73.e7 ◽  
Author(s):  
Donal McHugh ◽  
Nicole Caduff ◽  
Mario Henrique M. Barros ◽  
Patrick C. Rämer ◽  
Ana Raykova ◽  
...  
Keyword(s):  
Gene Expression ◽  
Tumor Formation ◽  
Lytic Gene ◽  
Kshv Infection ◽  
Lytic Gene Expression

scholarly journals Identification of the Essential Role of Viral Bcl-2 for Kaposi's Sarcoma-Associated Herpesvirus Lytic Replication

2015 ◽  
Vol 89 (10) ◽  
pp. 5308-5317 ◽  
Author(s):  
Qiming Liang ◽  
Brian Chang ◽  
Patrick Lee ◽  
Kevin F. Brulois ◽  
Jianning Ge ◽  
...  
Keyword(s):  
Gene Expression ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Dramatic Reduction ◽  
Viral Dna ◽  
Lytic Gene ◽  
Lytic Gene Expression ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACTKaposi's sarcoma-associated herpesvirus (KSHV) evades host defenses through tight suppression of autophagy by targeting each step of its signal transduction: by viral Bcl-2 (vBcl-2) in vesicle nucleation, by viral FLIP (vFLIP) in vesicle elongation, and by K7 in vesicle maturation. By exploring the roles of KSHV autophagy-modulating genes, we found, surprisingly, that vBcl-2 is essential for KSHV lytic replication, whereas vFLIP and K7 are dispensable. Knocking out vBcl-2 from the KSHV genome resulted in decreased lytic gene expression at the mRNA and protein levels, a lower viral DNA copy number, and, consequently, a dramatic reduction in the amount of progeny infectious viruses, as also described in the accompanying article (A. Gelgor, I. Kalt, S. Bergson, K. F. Brulois, J. U. Jung, and R. Sarid, J Virol 89:5298–5307, 2015). More importantly, the antiapoptotic and antiautophagic functions of vBcl-2 were not required for KSHV lytic replication. Using a comprehensive mutagenesis analysis, we identified that glutamic acid 14 (E14) of vBcl-2 is critical for KSHV lytic replication. Mutating E14to alanine totally blocked KSHV lytic replication but showed little or no effect on the antiapoptotic and antiautophagic functions of vBcl-2. Our study indicates that vBcl-2 harbors at least three important and genetically separable functions to modulate both cellular signaling and the virus life cycle.IMPORTANCEThe present study shows for the first time that vBcl-2 is essential for KSHV lytic replication. Removal of the vBcl-2 gene results in a lower level of KSHV lytic gene expression, impaired viral DNA replication, and consequently, a dramatic reduction in the level of progeny production. More importantly, the role of vBcl-2 in KSHV lytic replication is genetically separated from its antiapoptotic and antiautophagic functions, suggesting that the KSHV Bcl-2 carries a novel function in viral lytic replication.

scholarly journals Activation of Kaposi's Sarcoma-Associated Herpesvirus Lytic Gene Expression during Epithelial Differentiation

2005 ◽  
Vol 79 (21) ◽  
pp. 13769-13777 ◽  
Author(s):  
Andrew S. Johnson ◽  
Nicole Maronian ◽  
Jeffrey Vieira
Keyword(s):  
Gene Expression ◽  
Kaposi's Sarcoma ◽  
Fluorescent Protein ◽  
Kaposi’S Sarcoma ◽  
Epithelial Differentiation ◽  
Lytic Replication ◽  
Oral Epithelium ◽  
Lytic Gene ◽  
Lytic Gene Expression ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT The oral cavity has been identified as the major site for the shedding of infectious Kaposi's sarcoma-associated herpesvirus (KSHV). While KSHV DNA is frequently detected in the saliva of KSHV seropositive persons, it does not appear to replicate in salivary glands. Some viruses employ the process of epithelial differentiation for productive viral replication. To test if KSHV utilizes the differentiation of oral epithelium as a mechanism for the activation of lytic replication and virus production, we developed an organotypic raft culture model of epithelium using keratinocytes from human tonsils. This system produced a nonkeratinized stratified squamous oral epithelium in vitro, as demonstrated by the presence of nucleated cells at the apical surface; the expression of involucrin and keratins 6, 13, 14, and 19; and the absence of keratin 1. The activation of KSHV lytic-gene expression was examined in this system using rKSHV.219, a recombinant virus that expresses the green fluorescent protein during latency from the cellular EF-1α promoter and the red fluorescent protein (RFP) during lytic replication from the viral early PAN promoter. Infection of keratinocytes with rKSHV.219 resulted in latent infection; however, when these keratinocytes differentiated into a multilayered epithelium, lytic cycle activation of rKSHV.219 occurred, as evidenced by RFP expression, the expression of the late virion protein open reading frame K8.1, and the production of infectious rKSHV.219 at the epithelial surface. These findings demonstrate that KSHV lytic activation occurs as keratinocytes differentiate into a mature epithelium, and it may be responsible for the presence of infectious KSHV in saliva.

scholarly journals Cellular MicroRNAs 200b and 429 Regulate the Epstein-Barr Virus Switch between Latency and Lytic Replication

2010 ◽  
Vol 84 (19) ◽  
pp. 10329-10343 ◽  
Author(s):  
Amy L. Ellis-Connell ◽  
Tawin Iempridee ◽  
Iris Xu ◽  
Janet E. Mertz
Keyword(s):  
Gene Expression ◽  
Epstein Barr Virus ◽  
Family Members ◽  
Lytic Replication ◽  
Dependent Manner ◽  
Lytic Gene ◽  
Barr Virus ◽  
Ebv Infection ◽  
Lytic Gene Expression ◽  
Epstein Barr

ABSTRACT We previously showed that the cellular proteins ZEB1 and ZEB2/SIP1 both play key roles in regulating the latent-lytic switch of Epstein-Barr Virus (EBV) by repressing BZLF1 gene expression. We investigated here the effects of cellular microRNA (miRNA) 200 (miR200) family members on the EBV infection status of cells. We show that miR200b and miR429, but not miR200a, can induce EBV-positive cells into lytic replication by downregulating expression of ZEB1 and ZEB2, leading to production of infectious virus. The levels of miR200 family members in EBV-infected cells strongly negatively correlated with the levels of the ZEBs (e.g., −0.89 [P < 0.001] for miR429 versus ZEB1) and positively correlated with the degree of EBV lytic gene expression (e.g., 0.73 [P < 0.01] for miR429 versus BZLF1). The addition of either miR200b or miR429 to EBV-positive cells led to EBV lytic reactivation in a ZEB-dependent manner; inhibition of these miRNAs led to decreased EBV lytic gene expression. The degree of latent infection by an EBV mutant defective in the primary ZEB-binding site of the EBV BZLF1 promoter was not affected by the addition of these miRNAs. Furthermore, EBV infection of primary blood B cells led to downregulation of these miRNAs and upregulation of ZEB levels. Thus, we conclude that miRNAs 200b and 429 are key regulators via their effects on expression of ZEB1 and ZEB2 of the switch between latent and lytic infection by EBV and, therefore, potential targets for development of new lytic induction therapeutics with which to treat patients with EBV-associated malignancies.

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