scholarly journals DNA Binding and Modulation of Gene Expression by the Latency-Associated Nuclear Antigen of Kaposi's Sarcoma-Associated Herpesvirus

2001 ◽  
Vol 75 (17) ◽  
pp. 7882-7892 ◽  
Author(s):  
Alexander C. Garber ◽  
Marla A. Shu ◽  
Jianhong Hu ◽  
Rolf Renne
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Kaposi’S Sarcoma ◽  
Nuclear Antigen ◽  
Viral Gene ◽  
Mobility Shift ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. The latency-associated nuclear antigen (LANA) is highly expressed in these malignancies and has been shown to play an important role in episomal maintenance, presumably by binding to a putative oriP. In addition, LANA modulates cellular and viral gene expression and interacts with the cellular tumor suppressors p53 and retinoblastoma suppressor protein. Many of these features are reminiscent of Epstein-Barr virus nuclear antigens (EBNAs), a family of six proteins expressed during latency. EBNA-1 is required for episome maintenance, binds to oriP, and strongly activates transcription from two promoters, including its own. We have previously shown that LANA can transactivate its own promoter and therefore asked whether LANA, like EBNA-1, activates transcription by direct binding to DNA. By using recombinant LANA expressed from vaccinia virus vectors for electrophoretic mobility shift assays, we found that LANA does not bind to its own promoter. In contrast, LANA binds specifically to sequences containing an imperfect 20-bp palindrome in the terminal repeat (TR) of KSHV. We further show that the C-terminal domain of LANA is sufficient for site-specific DNA binding. Unlike EBNA-1, which activates transcription through binding of oriP, we found that LANA inhibits transcription from a single TR binding site. A multimerized TR as found in the viral genome results in strong transcriptional suppression when linked to a heterologous promoter. These data suggest that LANA, although fulfilling functions similar to those of EBNA-1, does so by very different mechanisms.

scholarly journals Modulation of Cellular and Viral Gene Expression by the Latency-Associated Nuclear Antigen of Kaposi's Sarcoma-Associated Herpesvirus

2001 ◽  
Vol 75 (1) ◽  
pp. 458-468 ◽  
Author(s):  
Rolf Renne ◽  
Chris Barry ◽  
Dirk Dittmer ◽  
Nicole Compitello ◽  
Patrick O. Brown ◽  
...  
Keyword(s):  
Gene Expression ◽  
Reporter Gene ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Viral Gene Expression ◽  
Kaposi’S Sarcoma ◽  
Nuclear Antigen ◽  
Viral Gene ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV), also called human herpesvirus 8 (HHV-8), is the likely etiological agent of Kaposi's sarcoma and primary effusion lymphoma. Common to these malignancies is that tumor cells are latently infected with KSHV. Viral gene expression is limited to a few genes, one of which is the latency-associated nuclear antigen (LANA), the product of ORF73. Examination of the primary sequence of LANA reveals some structural features reminiscent of transcription factors, leading us to hypothesize that LANA may regulate viral and cellular transcription during latency. In reporter gene-based transient transfection assays, we found that LANA can have either positive or negative effects on gene expression. While expression of a reporter gene from several synthetic promoters was increased in the presence of LANA, expression from the human immunodeficiency virus (HIV) long terminal repeat (LTR)—and from NF-κB-dependent reporter genes—was reduced by LANA expression. In addition, the promoter of KSHV ORF73 itself is activated up to 5.5-fold by LANA. This autoregulation may be important in tumorigenesis, because two other genes (v-cyclin and v-FLIP) with likely roles in cell growth and survival are also controlled by this element. To identify cellular genes influenced by LANA, we employed cDNA array-based expression profiling. Six known genes (and nine expressed sequence tags) were found to be upregulated in LANA-expressing cell lines. One of these, Staf-50, is known to inhibit expression from the HIV LTR; most of the other known genes are interferon inducible, although the interferon genes themselves were not induced by LANA. These data demonstrate that LANA expression has effects on cellular and viral gene expression. We suggest that, whether direct or indirect in origin, these effects may play important roles in the pathobiology of KSHV infection.

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 Inhibits Interleukin-4-Mediated STAT6 Phosphorylation To Regulate Apoptosis and Maintain Latency

2010 ◽  
Vol 84 (21) ◽  
pp. 11134-11144 ◽  
Author(s):  
Qiliang Cai ◽  
Subhash C. Verma ◽  
Ji-Young Choi ◽  
Michelle Ma ◽  
Erle S. Robertson
Keyword(s):  
Immune Response ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Kaposi’S Sarcoma ◽  
Cellular Growth ◽  
Interleukin 4 ◽  
Nuclear Antigen ◽  
Viral Agent ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Cytokine-mediated JAK/STAT signaling controls numerous important biologic responses like immune function, cellular growth, and differentiation. Inappropriate activation of this signaling pathway is associated with a range of malignancies. Kaposi's sarcoma-associated herpesvirus (KSHV) is the infectious viral agent associated with Kaposi's sarcoma and may also contribute to B-cell disorders, which include primary effusion lymphoma (PEL) and multicentric Castleman's disease. However, regulation of cytokine-mediated lymphocytic immune response by KSHV is not fully understood. In this report, we demonstrate that KSHV suppresses the interleukin-4 (IL-4)-stimulated immune response of B-lymphocyte activation and cell proliferation. Moreover, we show that the latency-associated nuclear antigen (LANA) encoded by KSHV is essential for viral blocking of IL-4-induced signaling. LANA reduces phosphorylation of the signal transducers and activators of transcription 6 (STAT6) on Y-641 and concomitantly its DNA binding ability. Importantly, knockdown of endogenous STAT6 dramatically increases the sensitivity of PEL cells to low-serum stress or chemical-mediated cellular apoptosis and reactivation of KSHV from latent replication. Thus, these findings suggest that the IL-4/STAT6 signaling network is precisely controlled by KSHV for survival, maintenance of latency, and suppression of the host cytokine immune response of the virus-infected cells.

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus LANA2 Is a B-Cell-Specific Latent Viral Protein That Inhibits p53

2001 ◽  
Vol 75 (1) ◽  
pp. 429-438 ◽  
Author(s):  
Carmen Rivas ◽  
Ai-En Thlick ◽  
Carlo Parravicini ◽  
Patrick S. Moore ◽  
Yuan Chang
Keyword(s):  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Blot Hybridization ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Nuclear Antigen ◽  
P53 Overexpression ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV), or human herpesvirus 8, is associated with three proliferative diseases ranging from viral cytokine-induced hyperplasia to monoclonal neoplasia: multicentric Castleman's disease (CD), Kaposi's sarcoma (KS), and primary effusion lymphoma (PEL). Here we report a new latency-associated 1,704-bp KSHV spliced gene belonging to a cluster of KSHV sequences having homology to the interferon regulatory factor (IRF) family of transcription factors. ORFK10.5 encodes a protein, latency-associated nuclear antigen 2 (LANA2), which is expressed in KSHV-infected hematopoietic tissues, including PEL and CD but not KS lesions. LANA2 is abundantly expressed in the nuclei of cultured KSHV-infected B cells. Transcription of K10.5 in PEL cell cultures is not inhibited by DNA polymerase inhibitors nor significantly induced by phorbol ester treatment. Unlike LANA1, LANA2 does not elicit a serologic response from patients with KS, PEL, or CD as measured by Western blot hybridization. Both KSHV vIRF1 (ORFK9) and LANA2 (ORFK10.5) appear to have arisen through gene duplication of a captured cellular IRF gene. LANA2 is a potent inhibitor of p53-induced transcription in reporter assays. LANA2 antagonizes apoptosis due to p53 overexpression in p53-null SAOS-2 cells and apoptosis due to doxorubicin treatment of wild-type p53 U2OS cells. While LANA2 specifically interacts with amino acids 290 to 393 of p53 in glutathione S-transferase pull-down assays, we were unable to demonstrate LANA2-p53 interaction in vivo by immunoprecipitation. These findings show that KSHV has tissue-specific latent gene expression programs and identify a new latent protein which may contribute to KSHV tumorigenesis in hematopoietic tissues via p53 inhibition.

scholarly journals A Cluster of Latently Expressed Genes in Kaposi’s Sarcoma-Associated Herpesvirus

1998 ◽  
Vol 72 (10) ◽  
pp. 8309-8315 ◽  
Author(s):  
Dirk Dittmer ◽  
Michael Lagunoff ◽  
Rolf Renne ◽  
Katherine Staskus ◽  
Ashley Haase ◽  
...  
Keyword(s):  
Rna Splicing ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Large Fraction ◽  
Kaposi’S Sarcoma ◽  
Nuclear Antigen ◽  
Reading Frame ◽  
Viral Genomes ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Infection with Kaposi’s sarcoma-associated herpesvirus (KSHV) is closely associated with Kaposi’s sarcoma (KS) and primary effusion lymphoma, with viral genomes present in a latent state in the majority of tumor cells. Here we describe a cluster of latently expressed viral genes whose mRNAs are generated from a common promoter. Two mRNAs in this region encode the latency-associated nuclear antigen, the product of open reading frame 73 (ORF73). The larger RNA, of 5.8 kb, is an unspliced transcript that includes ORF72 and -71 at its 3′ end; it initiates at nucleotides (nt) 127880 to 127886 from a promoter lacking recognizable TATA elements. A less abundant mRNA, of 5.4 kb, is a variant of this transcript, in which 336 nt of 5′ noncoding information has been removed by RNA splicing. A third, more abundant RNA is generated from the same promoter region via splicing from the common splice donor at nt 127813 to an acceptor 5′ to ORF72; this transcript is the presumed mRNA for ORF72, which encodes the viral cyclin D homolog. All three RNAs are 3′ coterminal. In situ hybridization analysis with probes that can detect all three transcripts shows that the RNAs are detectable in a large fraction of BCBL-1 cells prior to lytic induction and in >70% of KS spindle cells in primary KS tumors. This confirms that these transcripts are indeed latent RNAs and suggests a role for their products in viral persistence and/or KSHV-associated proliferation.

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus Latent and Lytic Gene Expression as Revealed by DNA Arrays

2001 ◽  
Vol 75 (2) ◽  
pp. 891-902 ◽  
Author(s):  
Richard G. Jenner ◽  
M. Mar Albà ◽  
Chris Boshoff ◽  
Paul Kellam
Keyword(s):  
Gene Expression ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Dna Arrays ◽  
Nylon Membrane ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) is associated with three human tumors, Kaposi's sarcoma, primary effusion lymphoma (PEL), and multicentric Castleman's disease. KSHV encodes a number of homologs of cellular proteins involved in the cell cycle, signal transduction, and modulation of the host immune response. Of the virus complement of over 85 open reading frames (ORFs), the expression of only a minority has been characterized individually. We have constructed a nylon membrane-based DNA array which allows the expression of almost every ORF of KSHV to be measured simultaneously. A PEL-derived cell line, BC-3, was used to study the expression of KSHV during latency and after the induction of lytic replication. Cluster analysis, which arranges genes according to their expression profile, revealed a correlation between expression and assigned gene function that is consistent with the known stages of the herpesvirus life cycle. Furthermore, latent and lytic genes thought to be functionally related cluster into groups. The correlation between gene expression and function also infers possible roles for KSHV genes yet to be characterized.

scholarly journals A Potential α-Helix Motif in the Amino Terminus of LANA Encoded by Kaposi's Sarcoma-Associated Herpesvirus Is Critical for Nuclear Accumulation of HIF-1α in Normoxia

2007 ◽  
Vol 81 (19) ◽  
pp. 10413-10423 ◽  
Author(s):  
Qiliang Cai ◽  
Masanao Murakami ◽  
Huaxin Si ◽  
Erle S. Robertson
Keyword(s):  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Kaposi’S Sarcoma ◽  
Hek293 Cells ◽  
Nuclear Accumulation ◽  
Nuclear Antigen ◽  
Cytokine Signaling ◽  
Amino Terminal ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Hypoxia-inducible factor 1 (HIF-1) is a ubiquitously expressed transcriptional regulator involved in induction of numerous genes associated with angiogenesis and tumor growth. Kaposi's sarcoma, associated with increased angiogenesis, is a highly vascularized, endothelial cell-derived tumor. Previously, we have shown that the latency-associated nuclear antigen (LANA) encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) targets the HIF-1α suppressors von Hippel-Lindau protein and p53 for degradation via its suppressor of cytokine signaling-box motif, which recruits the EC5S ubiquitin complex. Here we further show that HIF-1α was aberrantly accumulated in KSHV latently infected primary effusion lymphoma (PEL) cells, as well as HEK293 cells infected with KSHV, and also show that a potential α-helical amino-terminal domain of LANA was important for HIF-1α nuclear accumulation in normoxic conditions. Moreover, we have now determined that this association was dependent on the residues 46 to 89 of LANA and the oxygen-dependent degradation domain of HIF-1α. Introduction of specific small interfering RNA against LANA into PEL cells also resulted in a diminished nuclear accumulation of HIF-1α. Therefore, these data show that LANA can function not only as an inhibitor of HIF-1α suppressor proteins but can also induce nuclear accumulation of HIF-1α during KSHV latent infection.

scholarly journals Latent Nuclear Antigen of Kaposi’s Sarcoma-Associated Herpesvirus Interacts with RING3, a Homolog of theDrosophila Female Sterile Homeotic (fsh) Gene

1999 ◽  
Vol 73 (12) ◽  
pp. 9789-9795 ◽  
Author(s):  
Georgina M. Platt ◽  
Guy R. Simpson ◽  
Sibylle Mittnacht ◽  
Thomas F. Schulz
Keyword(s):  
Protein Interactions ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Kaposi’S Sarcoma ◽  
Nuclear Antigen ◽  
Latently Infected ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Carboxy Terminal ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
Latent Nuclear Antigen

ABSTRACT Kaposi’s sarcoma-associated herpesvirus (KSHV/HHV-8) is the likely infectious cause of Kaposi’s sarcoma, primary effusion lymphoma, and some cases of multicentric Castleman’s disease. Its latent nuclear antigen (LANA) is expressed in the nuclei of latently infected cells and may play a role in the persistence of episomal viral DNA in dividing cells. Here we report that LANA interacts with RING3, a nuclear protein and member of the Drosophila fsh (female sterile homeotic) family of proteins, some of which have previously been implicated in controlling gene expression. Binding of RING3 to LANA involves the ET domain, characteristic of fsh-related proteins, suggesting that this highly conserved region is involved in protein-protein interactions. The interaction between RING3 and LANA results in phosphorylation of serine and threonine residues located between amino acids 951 and 1107 in the carboxy-terminal region of LANA. However, RING3 is not itself a kinase but appears to recruit an as yet unidentified serine/threonine protein kinase into the complex which it forms with LANA.

scholarly journals Kaposi’s Sarcoma-Associated Herpesvirus Drives a Super-Enhancer-Mediated Survival Gene Expression Program in Primary Effusion Lymphoma

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Mark Manzano ◽  
Thomas Günther ◽  
Hyunwoo Ju ◽  
John Nicholas ◽  
Elizabeth T. Bartom ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Kaposi’S Sarcoma ◽  
Cellular Transcription Factor ◽  
Super Enhancer ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
Expression Program

ABSTRACT Kaposi’s sarcoma-associated herpesvirus (KSHV) causes primary effusion lymphoma (PEL). The cellular transcription factor (TF) interferon (IFN) regulatory factor 4 (IRF4) is an essential oncogene in PEL, but its specific role in PEL and how KSHV deregulates IRF4 remain unknown. Here, we report that the KSHV latency protein viral interferon regulatory factor 3 (vIRF3) cooperates with IRF4 and cellular BATF (basic leucine zipper ATF-like TF) to drive a super-enhancer (SE)-mediated oncogenic transcriptional program in PEL. Chromatin immunoprecipitation coupled with next-generation sequencing (ChIP-Seq) experiments demonstrated that IRF4, vIRF3, and BATF cooccupy the SEs of key survival genes, in a pattern that is distinct from those seen with other IRF4-driven malignancies. All three proteins cooperatively drive SE-mediated IRF4 overexpression. Inactivation of vIRF3 and, to a lesser extent, BATF phenocopies the gene expression changes and loss of cellular viability observed upon inactivation of IRF4. In sum, this work suggests that KSHV vIRF3 and cellular IRF4 and BATF cooperate as oncogenic transcription factors on SEs to promote cellular survival and proliferation in KSHV-associated lymphomas. IMPORTANCE Kaposi’s sarcoma-associated herpesvirus (KSHV) causes the aggressive disease primary effusion lymphoma (PEL). Here, we show that a viral transcription factor (vIRF3) cooperates with the cellular transcription factor IRF4 to control an oncogenic gene expression program in PEL cells. These proteins promote KSHV-mediated B cell transformation by activating the expression of prosurvival genes through super-enhancers. Our report thus demonstrates that this DNA tumor virus encodes a transcription factor that functions with cellular IRF4 to drive oncogenic transcriptional reprogramming.

scholarly journals The Latency-Associated Nuclear Antigen of Kaposi's Sarcoma-Associated Herpesvirus Supports Latent DNA Replication in Dividing Cells

2002 ◽  
Vol 76 (22) ◽  
pp. 11677-11687 ◽  
Author(s):  
Jianhong Hu ◽  
Alexander C. Garber ◽  
Rolf Renne
Keyword(s):  
Amino Acid ◽  
Dna Replication ◽  
Dna Binding ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Terminal Repeat ◽  
Nuclear Antigen ◽  
Dividing Cells ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. The latency-associated nuclear antigen (LANA) is a multifunctional protein that is consistently expressed in all KSHV-associated malignancies. LANA interacts with a variety of cellular proteins, including the transcriptional cosuppressor complex mSin3 and the tumor suppressors p53 and Rb, thereby regulating viral and cellular gene expression. In addition, LANA is required for maintenance of the episomal viral DNA during latency in dividing cells. Colocalization studies suggest that LANA tethers the viral genome to chromosomes during mitosis. In support of this model, a specific LANA- binding site has recently been identified within the terminal repeat unit, and a chromatin interaction domain was mapped to a short amino acid stretch within the N-terminal domain of LANA. Epstein-Barr virus nuclear antigen 1 (EBNA-1), a functional homologue of LANA, is also required for genome segregation; in addition, EBNA-1 also supports efficient DNA replication of oriP-containing plasmids. By performing short-term replication assays, we demonstrate here for the first time that de novo synthesis of terminal-repeat (TR)-containing plasmids is highly dependent on the presence of LANA. We map the required cis-acting sequences within the TR to a 79-bp region and demonstrate that the DNA-binding domain of LANA is required for this DNA replication activity. Surprisingly, the 233-amino-acid C domain of LANA by itself partially supports replication. Our data show that LANA is a sequence-specific DNA-binding protein that, like EBNA-1, plays an important role in DNA replication and genome segregation. In addition, we show that all necessary cis elements for the origin of replication (ori) function are located within a single TR, suggesting that the putative ori of KSHV is different from those of other gammaherpesviruses, which all contain ori sequences within the unique long sequence outside of their TR. This notion is further strengthened by the unique modular structure of the KSHV TR element.

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