Decreased immunoreactivity for cell-cycle regulator p27Kip1 in Kaposi's sarcoma correlates with higher stage and extracutaneous involvement

ABSTRACT In order to cope with hostile host environments, many viruses have developed strategies to perturb the cellular machinery to suit their replication needs. Some herpesvirus genes protect cells from undergoing apoptosis to prolong the lives of infected cells, while others, such as Epstein-Barr virus Zta, slow down the G1/S transition phase to allow ample opportunity for transcription and translation of viral genes before the onset of cellular genomic replication. In this study, we investigated whether Kaposi's sarcoma-associated herpesvirus (KSHV) K-bZIP, a homologue of the Epstein-Barr virus transcription factor BZLF1 (Zta), plays a role in cell cycle regulation. Here we show that K-bZIP physically associates with cyclin-CDK2 and downmodulates its kinase activity. The association can be detected in the natural environment of KSHV-infected cells without artificial overexpression of either component. With purified protein, it can be shown that the interaction between K-bZIP and cyclin-CDK2 is direct and that K-bZIP alone is sufficient to inhibit CDK2 activity. The interacting domain of K-bZIP has been mapped to the basic region. The result of these associations is a prolonged G1 phase, accompanied by the induction of p21 and p27 in a naturally infected B-cell line. Thus, in addition to the previously described transcription and genome replication functions, a new role of K-bZIP in KSHV replication is identified in this report.

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Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Induces Expression of the Helix-Loop-Helix Protein Id-1 in Human Endothelial Cells

Journal of Virology ◽

10.1128/jvi.77.10.5975-5984.2003 ◽

2003 ◽

Vol 77 (10) ◽

pp. 5975-5984 ◽

Cited By ~ 37

Author(s):

Jun Tang ◽

Gabriel M. Gordon ◽

Maike G. Müller ◽

Madhu Dahiya ◽

Kimberly E. Foreman

Keyword(s):

Cell Cycle ◽

Endothelial Cells ◽

Tumor Cells ◽

Cell Cycle Regulation ◽

Kaposi's Sarcoma ◽

Human Herpesvirus ◽

Kaposi’S Sarcoma ◽

Nuclear Antigen ◽

Helix Loop Helix ◽

Cycle Regulation

ABSTRACT Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) (also known as human herpesvirus 8) is a gamma-2 herpesvirus believed to be the etiologic agent responsible for KS. The pathogenesis of this potentially life-threatening neoplasm is complex and unclear, and it is currently unknown how KSHV causes KS. Id (named for inhibitor of DNA binding or inhibitor of differentiation) proteins were identified in 1990 and found to be naturally occurring dominant-negative inhibitors of basic helix-loop-helix transcription factors. Id-1, the most well-studied member of this family, has since been shown to play a key role in several biological systems including cellular differentiation, cell cycle regulation, and tumorigenesis. In this report, we demonstrate that Id-1 is expressed at high levels in KS tumor cells both in vitro and in vivo but is expressed at relatively modest levels in endothelial cells (ECs), the likely precursor of the KS tumor cell. Infection of precursor cells with KSHV may be responsible for this enhanced expression, as KSHV infection induced Id-1 27-fold in ECs under our experimental conditions. Furthermore, we demonstrate that the KSHV-encoded latency-associated nuclear antigen (LANA) protein appears to be involved. Expression of LANA in ECs resulted in Id-1 induction that was almost identical to the induction seen with KSHV-infected ECs. These results demonstrate the expression of Id-1 in KS tumor cells and indicate the KSHV LANA protein may be, at least in part, responsible. This may be an important mechanism by which KSHV allows KS tumor cells to escape normal cell cycle regulation and enhances their proliferation.

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Regulation of growth signalling and cell cycle by Kaposi's sarcoma-associated herpesvirus genes

International Journal of Experimental Pathology ◽

10.1111/j.0959-9673.2004.00407.x ◽

2004 ◽

Vol 85 (6) ◽

pp. 305-319 ◽

Cited By ~ 28

Author(s):

Shamindra Direkze ◽

Heike Laman

Keyword(s):

Cell Cycle ◽

Kaposi's Sarcoma ◽

Kaposi’S Sarcoma ◽

Kaposi's Sarcoma Associated Herpesvirus ◽

Kaposi’S Sarcoma Associated Herpesvirus ◽

Regulation Of Growth

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Kaposi's Sarcoma-Associated Herpesvirus Viral Interferon Regulatory Factor 4 (vIRF4) Perturbs the G1-S Cell Cycle Progression via Deregulation of thecyclin D1Gene

Journal of Virology ◽

10.1128/jvi.01897-15 ◽

2015 ◽

Vol 90 (2) ◽

pp. 1139-1143 ◽

Cited By ~ 10

Author(s):

Hye-Ra Lee ◽

Jaba Mitra ◽

Stacy Lee ◽

Shou-Jiang Gao ◽

Tae-Kwang Oh ◽

...

Keyword(s):

Cell Cycle ◽

Kaposi's Sarcoma ◽

Cell Cycle Progression ◽

Kaposi’S Sarcoma ◽

Regulatory Factor ◽

Cycle Progression ◽

Kaposi's Sarcoma Associated Herpesvirus ◽

Interferon Regulatory Factor 4 ◽

Kaposi’S Sarcoma Associated Herpesvirus ◽

Intracellular Milieu

Kaposi's sarcoma-associated herpesvirus (KSHV) infection modulates the host cell cycle to create an environment optimal for its viral-DNA replication during the lytic life cycle. We report here that KSHV vIRF4 targets the β-catenin/CBP cofactor and blocks its occupancy on thecyclin D1promoter, suppressing the G1-S cell cycle progression and enhancing KSHV replication. This shows that KSHV vIRF4 suppresses host G1-S transition, possibly providing an intracellular milieu favorable for its replication.

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Identifying cellular genes crucial for the reactivation of Kaposi's sarcoma-associated herpesvirus latency

Journal of General Virology ◽

10.1099/vir.0.81603-0 ◽

2006 ◽

Vol 87 (3) ◽

pp. 519-529 ◽

Cited By ~ 16

Author(s):

Benjaman A. Bryan ◽

Ossie F. Dyson ◽

Shaw M. Akula

Keyword(s):

Cell Cycle ◽

Flow Cytometry ◽

Kaposi's Sarcoma ◽

Kaposi’S Sarcoma ◽

S Phase ◽

Lytic Cycle ◽

Kshv Infection ◽

Cellular Genes ◽

Kaposi's Sarcoma Associated Herpesvirus ◽

Kaposi’S Sarcoma Associated Herpesvirus

Kaposi's sarcoma-associated herpesvirus (KSHV) is the latest addition to the long list of human herpesviruses. Reactivation of latent herpesvirus infections is still a mystery. It was demonstrated recently that the phorbol ester TPA was efficient in inducing a reactivation of KSHV infection in the S phase of the cell cycle. In the present study, flow cytometry-sorted, TPA-induced, KSHV-infected haematopoietic cells (BCBL-1) were used to analyse the expression profiles of cancer-related cellular genes in the S phase of the cell cycle compared with the G0/1 phase by using microarrays. Overall, the S phase of the cell cycle seems to provide KSHV with an apt environment for a productive lytic cycle of infection. The apt conditions include cellular signalling that promotes survivability, DNA replication and lipid metabolism, while blocking cell-cycle progression to M phase. Some of the important genes that were overexpressed during the S phase of the cell cycle compared with the G0/1 phase of TPA-induced BCBL-1 cells are v-myb myeloblastosis (MYBL2), protein kinase-membrane associated tyrosine/threonine 1 (PKMYT1), ribonucleotide reductase M1 polypeptide (RRM1) and peroxisome proliferator-activated receptors delta (PPARD). Inhibition of PKMYT1 expression by the use of specific short interfering RNAs significantly lowered the TPA-induced KSHV lytic cycle of infection. The significance of these and other genes in the reactivation of KSHV is discussed in the following report. Taken together, a flow cytometry–microarray-based method to study the cellular conditions critical for the reactivation of KSHV infection is reported here for the first time.

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ORF73 of Herpesvirus Saimiri, a Viral Homolog of Kaposi's Sarcoma-Associated Herpesvirus, Modulates the Two Cellular Tumor Suppressor Proteins p53 and pRb

Journal of Virology ◽

10.1128/jvi.78.19.10336-10347.2004 ◽

2004 ◽

Vol 78 (19) ◽

pp. 10336-10347 ◽

Cited By ~ 31

Author(s):

Sumit Borah ◽

Subhash C. Verma ◽

Erle S. Robertson

Keyword(s):

Cell Cycle ◽

Kaposi's Sarcoma ◽

Kaposi’S Sarcoma ◽

Herpesvirus Saimiri ◽

Nuclear Antigen ◽

Kaposi's Sarcoma Associated Herpesvirus ◽

Kaposi’S Sarcoma Associated Herpesvirus ◽

P53 Inactivation

ABSTRACT All known DNA tumor viruses are known to target and inactivate two main cell cycle regulatory proteins, retinoblastoma protein (pRb) and p53. Inactivation of pRb promotes host cell cycle progression into S phase, and inactivation of p53 promotes cell immortalization. The DNA tumor virus Kaposi's sarcoma associated herpesvirus (KSHV)-encoded latency-associated nuclear antigen (LANA) was shown to target and inactivate pRb as well as p53. In this report we provide evidence that these functions are conserved in the homologous protein encoded by the related gammaherpesvirus herpesvirus saimiri (HVS). ORF73, the HVS homologue of LANA, is shown to bind both p53 and pRb in vitro and in vivo, to colocalize with p53 in human T cells infected with HVS, and in cells overexpressing both ORF73 and p53, as well as to adversely influence pRB/E2F and p53 transcriptional regulation. The C terminus of LANA, the region most highly conserved in ORF73, is shown to be responsible for both pRb and p53 interactions, supporting the hypothesis that these functions are conserved in both homologues. Finally, the region of p53 targeted by LANA (and ORF73) maps to the domain required for tetramerization. However, preliminary cross-linking studies do not detect disruption of p53 tetramerization by either LANA or HVS-encoded ORF73, suggesting that p53 inactivation may be by a mechanism independent of tetramer disruption.

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Myc Is Required for the Maintenance of Kaposi's Sarcoma-Associated Herpesvirus Latency

Journal of Virology ◽

10.1128/jvi.00244-10 ◽

2010 ◽

Vol 84 (17) ◽

pp. 8945-8948 ◽

Cited By ~ 27

Author(s):

Xudong Li ◽

Shijia Chen ◽

Jun Feng ◽

Hongyu Deng ◽

Ren Sun

Keyword(s):

Cell Cycle ◽

Kaposi's Sarcoma ◽

Promoter Activity ◽

Primary Effusion Lymphoma ◽

Kaposi’S Sarcoma ◽

Cellular Transformation ◽

Mrna Levels ◽

Cycle Arrest ◽

Kaposi's Sarcoma Associated Herpesvirus ◽

Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Myc is deregulated by Kaposi's sarcoma-associated herpesvirus (KSHV) latent proteins, but its role in KSHV latency is not clear. We found that Myc knockdown with RNA interference (RNAi) induced KSHV reactivation and increased the protein and mRNA levels of RTA, a key viral regulator of KSHV reactivation. Myc knockdown increased, whereas Myc overexpression inhibited, RTA promoter activity. KSHV reactivation and the activation of the RTA promoter induced by Myc depletion were inhibited by c-Jun N-terminal kinase (JNK) and p38 inhibitors but not by a MEK1 inhibitor. Myc knockdown inhibited primary effusion lymphoma (PEL) cell proliferation through inducing apoptosis and G1 cell cycle arrest. Thus, Myc may be a key cellular node coupling cellular transformation and KSHV latency.

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Modified Cross-Linking, Ligation, and Sequencing of Hybrids (qCLASH) Identifies Kaposi's Sarcoma-Associated Herpesvirus MicroRNA Targets in Endothelial Cells

Journal of Virology ◽

10.1128/jvi.02138-17 ◽

2018 ◽

Vol 92 (8) ◽

Cited By ~ 13

Author(s):

Lauren A. Gay ◽

Sunantha Sethuraman ◽

Merin Thomas ◽

Peter C. Turner ◽

Rolf Renne

Keyword(s):

Cell Cycle ◽

Endothelial Cells ◽

Endothelial Cell ◽

Cell Line ◽

Kaposi's Sarcoma ◽

Cell Cycle Control ◽

Kaposi’S Sarcoma ◽

Cross Linking ◽

Wild Type ◽

Latently Infected

ABSTRACTKaposi's sarcoma (KS) tumors are derived from endothelial cells and express Kaposi's sarcoma-associated herpesvirus (KSHV) microRNAs (miRNAs). Although miRNA targets have been identified in B cell lymphoma-derived cells and epithelial cells, little has been done to characterize the KSHV miRNA targetome in endothelial cells. A recent innovation in the identification of miRNA targetomes, cross-linking, ligation, and sequencing of hybrids (CLASH), unambiguously identifies miRNAs and their targets by ligating the two species while both species are still bound within the RNA-induced silencing complex (RISC). We developed a streamlined quick CLASH (qCLASH) protocol that requires a lower cell input than the original method and therefore has the potential to be used on patient biopsy samples. Additionally, we developed a fast-growing, KSHV-negative endothelial cell line derived from telomerase-immortalized vein endothelial long-term culture (TIVE-LTC) cells. qCLASH was performed on uninfected cells and cells infected with either wild-type KSHV or a mutant virus lacking miR-K12-11/11*. More than 1,400 cellular targets of KSHV miRNAs were identified. Many of the targets identified by qCLASH lacked a canonical seed sequence match. Additionally, most target regions in mRNAs originated from the coding DNA sequence (CDS) rather than the 3′ untranslated region (UTR). This set of genes includes some that were previously identified in B cells and some new genes that warrant further study. Pathway analysis of endothelial cell targets showed enrichment in cell cycle control, apoptosis, and glycolysis pathways, among others. Characterization of these new targets and the functional consequences of their repression will be important in furthering our understanding of the role of KSHV miRNAs in oncogenesis.IMPORTANCEKS lesions consist of endothelial cells latently infected with KSHV. Cells that make up these lesions express KSHV miRNAs. Identification of the targets of KSHV miRNAs will help us understand their role in viral oncogenesis. The cross-linking and sequencing of hybrids (CLASH) protocol is a method for unambiguously identifying miRNA targetomes. We developed a streamlined version of CLASH, called quick CLASH (qCLASH). qCLASH requires a lower initial input of cells than for its parent protocol. Additionally, a new fast-growing KSHV-negative endothelial cell line, named TIVE-EX-LTC cells, was established. qCLASH was performed on TIVE-EX-LTC cells latently infected with wild-type (WT) KSHV or a mutant virus lacking miR-K12-11/11*. A number of novel targets of KSHV miRNAs were identified, including targets of miR-K12-11, the ortholog of the cellular oncogenic miRNA (oncomiR) miR-155. Many of the miRNA targets were involved in processes related to oncogenesis, such as glycolysis, apoptosis, and cell cycle control.

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Kaposi's Sarcoma-Associated Herpesvirus LANA-1 Interacts with the Short Variant of BRD4 and Releases Cells from a BRD4- and BRD2/RING3-Induced G1 Cell CycleArrest

Journal of Virology ◽

10.1128/jvi.00804-06 ◽

2006 ◽

Vol 80 (21) ◽

pp. 10772-10786 ◽

Cited By ~ 101

Author(s):

Matthias Ottinger ◽

Thomas Christalla ◽

Kavita Nathan ◽

Melanie M. Brinkmann ◽

Abel Viejo-Borbolla ◽

...

Keyword(s):

Cell Cycle ◽

Kaposi's Sarcoma ◽

Promoter Activity ◽

Cyclin E ◽

Direct Interaction ◽

Kaposi’S Sarcoma ◽

S Phase ◽

Kaposi's Sarcoma Associated Herpesvirus ◽

Carboxy Terminal ◽

Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT The Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen 1 (LANA-1) is required for the replication of episomal viral genomes. Regions in its N-terminal and C-terminal domains mediate the interaction with host cell chromatin. Several cellular nuclear proteins, e.g., BRD2/RING3, histones H2A and H2B, MeCP2, DEK, and HP1α, have been suggested to mediate this interaction. In this work, we identify the double-bromodomain proteins BRD4 and BRD3/ORFX as additional LANA-1 interaction partners. The carboxy-terminal region of the short variant of BRD4 (BRD4S) containing the highly conserved extraterminal domain directly interacts with an element in the LANA-1 carboxy-terminal domain. We show that ectopically expressed BRD4S and BRD2/RING3 delay progression into the S phase of the cell cycle in epithelial and B-cell lines and increase cyclin E promoter activity. LANA-1 partly releases epithelial and B cells from a BRD4S- and BRD2/RING3-induced G1 cell cycle arrest and also promotes S-phase entry in the presence of BRD4S and BRD2/RING3. This is accompanied by a reduction in BRD4S-mediated cyclin E promoter activity. Our data are in keeping with the notion that the direct interaction of KSHV LANA-1 with BRD4 and other BRD proteins could play a role in the G1/S phase-promoting functions of KSHV LANA-1. Further, our data support a model in which the LANA-1 C terminus contributes to a functional attachment to acetylated histones H3 and H4 via BRD4 and BRD2, in addition to the recently demonstrated direct interaction (A. J. Barbera, J. V. Chodaparambil, B. Kelley-Clarke, V. Joukov, J. C. Walter, K. Luger, and K. M. Kaye, Science 311:856-861, 2006) of the LANA-1 N terminus with histones H2A and H2B.

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