scholarly journals Interaction of Papillomavirus E2 Protein with the Brm Chromatin Remodeling Complex Leads to Enhanced Transcriptional Activation

2006 ◽  
Vol 81 (5) ◽  
pp. 2213-2220 ◽  
Author(s):  
R. Ajay Kumar ◽  
Samisubbu R. Naidu ◽  
Xiaoyu Wang ◽  
Anthony N. Imbalzano ◽  
Elliot J. Androphy
Keyword(s):  
Chromatin Remodeling ◽  
Transcriptional Activation ◽  
Potential Interaction ◽  
Transactivation Domain ◽  
Reporter System ◽  
Barr Virus ◽  
Amino Terminal ◽  
Chromatin Remodeling Complex ◽  
Epstein Barr

ABSTRACT Papillomavirus E2 is a sequence-specific DNA binding protein that regulates transcription and replication of the viral genome. The transcriptional activities of E2 are typically evaluated by transient transfection of nonreplicating E2-dependent reporters. We sought to address whether E2 activates transcription in an episomal context and its potential interaction with the chromatin remodeling proteins. Using an Epstein-Barr virus-based episomal reporter, we demonstrate that E2 stimulates transcription from an E2-dependent promoter in a chromatin context. This activation is enhanced by the presence of proteins associated with SWI/SNF complexes, which are ATP-dependent chromatin remodeling enzymes. We show that exogenous expression of the Brm ATPase enhances E2 activity in SWI/SNF-deficient cell lines and that the amino-terminal transactivation domain of E2 mediates association with the Brm complex in vivo. Using chromatin immunoprecipitation assays, we demonstrate that Brm enhances promoter occupancy by E2 in an episomal context. Our results demonstrate that E2 activates transcription from an episomal reporter system and reveal a novel property of E2 in collaborating with the Brm chromatin remodeling complex in enhancing transcriptional activation.

LYDMA-antigens and Immunity against EBV-infected Cells Epstein-Barr Virus as a Model for the Study of Host-infection Interaction

1987 ◽  
Vol 2 (2) ◽  
pp. 125-132 ◽  
Author(s):  
Maria L. Villa ◽  
Emilio Bombardieri
Keyword(s):  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Dna Viruses ◽  
Barr Virus ◽  
Good Potential ◽  
Infected Cells ◽  
Membrane Antigens ◽  
Epstein Barr ◽  
Host Infection

Molecular biology has shown that DNA viruses carry their own transforming genes, unlike RNA viruses (retrovirus), which use cellular “oncogenes”. Some of the products of transforming viral genes are very good potential targets for immune defence. Epstein-Barr virus (EBV) immortalization is linked to the transcriptional activation of some latently transcribed regions; the lymphocyte-determined membrane antigens (LYDMA), the product of one of these regions, are the T-cell's chosen target. EBV-induced immortalization may therefore be free from any malignant consequence as long as immortalized clones are suppressed by immunosurveillance. In vivo, LYDMA-positive clones may be susceptible to immune control; LYDMA-negative clones can transform to neoplastic cells

scholarly journals The CBP Bromodomain and Nucleosome Targeting Are Required for Zta-Directed Nucleosome Acetylation and Transcription Activation

2003 ◽  
Vol 23 (8) ◽  
pp. 2633-2644 ◽  
Author(s):  
Zhong Deng ◽  
Chi-Ju Chen ◽  
Michaela Chamberlin ◽  
Fang Lu ◽  
Gerd A. Blobel ◽  
...  
Keyword(s):  
Complex Formation ◽  
Histone Acetylation ◽  
Protein Sequencing ◽  
Creb Binding Protein ◽  
Barr Virus ◽  
Amino Terminal ◽  
Viral Promoters ◽  
Epstein Barr

ABSTRACT The Epstein-Barr virus (EBV)-encoded lytic activator Zta is a bZIP protein that can stimulate nucleosomal histone acetyltransferase (HAT) activity of the CREB binding protein (CBP) in vitro. We now show that deletion of the CBP bromo- and C/H3 domains eliminates stimulation of nucleosomal HAT activity in vitro and transcriptional coactivation by Zta in transfected cells. In contrast, acetylation of free histones was not affected by the addition of Zta or by deletions in the bromo or C/H3 domain of CBP. Zta stimulated acetylation of oligonucleosomes assembled on supercoiled DNA and dinucleosomes assembled on linear DNA, but Zta-stimulated acetylation was significantly reduced for mononucleosomes. Western blotting and amino-terminal protein sequencing indicated that all lysine residues in the H3 and H4 amino-terminal tails were acetylated by CBP and enhanced by the addition of Zta. Histone acetylation was also dependent upon the Zta basic DNA binding domain, which could not be substituted with the homologous basic region of c-Fos, indicating specificity in the bZIP domain nucleosome binding function. Finally, we show that Zta and CBP colocalize to viral immediate-early promoters in vivo and that overexpression of Zta leads to a robust increase in H3 and H4 acetylation at various regions of the EBV genome in vivo. Furthermore, deletion of the CBP bromodomain reduced stable CBP-Zta complex formation and histone acetylation at Zta-responsive viral promoters in vivo. These results suggest that activator- and bromodomain-dependent targeting to oligonucleosomal chromatin is required for stable promoter-bound complex formation and transcription activity.

scholarly journals The LMP1 Promoter Can Be Transactivated Directly by NF-κB

2009 ◽  
Vol 83 (10) ◽  
pp. 5269-5277 ◽  
Author(s):  
Constantinos Demetriades ◽  
George Mosialos
Keyword(s):  
Binding Sites ◽  
Bioinformatic Analysis ◽  
Latent Membrane Protein 1 ◽  
Reporter System ◽  
Barr Virus ◽  
Aryl Hydrocarbon ◽  
Lmp1 Expression ◽  
Epstein Barr

ABSTRACT A bioinformatic analysis identified two putative NF-κB binding sites in the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) promoter. The ability of p65RelA to interact with the LMP1 promoter was shown by in vitro and in vivo assays. Using an EBV-transformed lymphoblastoid cell line as a reporter system for the activity of the +40/−328 LMP1 promoter region, the functional importance of NF-κB and other transcription factor binding sites was demonstrated. p65RelA could also induce LMP1 expression from the EBV genome in Daudi and P3HR1 Burkitt's lymphoma cell lines. Finally, it was shown that p65RelA could cooperate with EBNA2 or the aryl hydrocarbon receptor in the transactivation of the LMP1 promoter. Our study established the importance of NF-κB and several cis-acting elements in the regulation of the LMP1 promoter in a latency III environment and highlighted a complex interplay between NF-κB and other transcription factors in this process.

scholarly journals Two Distinct Mechanisms of Chromatin Interaction by the Isw2 Chromatin Remodeling Complex In Vivo

2005 ◽  
Vol 25 (21) ◽  
pp. 9165-9174 ◽  
Author(s):  
Thomas G. Fazzio ◽  
Marnie E. Gelbart ◽  
Toshio Tsukiyama
Keyword(s):  
Chromatin Remodeling ◽  
Dna Binding Proteins ◽  
Chromatin Interaction ◽  
Chromatin Binding ◽  
Histone H4 ◽  
Amino Terminal ◽  
Histone Octamer ◽  
Chromatin Remodeling Complex ◽  
Specific Association

ABSTRACT We have previously shown that Saccharomyces cerevisiae Isw2 complex slides nucleosomes to remodel chromatin in vivo. Our data suggested a model in which Isw2 complex binds the histone octamer and DNA separately to generate the force necessary for nucleosome movement. Here we find that the histone H4 “basic patch” is the only portion of any amino-terminal histone tail required for both target-specific association of Isw2 complex with chromatin and chromatin remodeling in vivo, whereas it is dispensable for basal levels of chromatin binding. Similarly, we find that nonremodeled chromatin structure and integrity of Isw2 complex are required only for target-specific association of Isw2 with chromatin. These data demonstrate fundamental differences between the target-specific and basal modes of chromatin binding by Isw2 complex in vivo and suggest that only the former involves contributions from DNA, histone H4, and sequence-specific DNA binding proteins. We propose a model for target recognition and chromatin remodeling by Isw2 complex in vivo.

scholarly journals Effective Formation of the Segregation-Competent Complex Determines Successful Partitioning of the Bovine Papillomavirus Genome during Cell Division

2010 ◽  
Vol 84 (21) ◽  
pp. 11175-11188 ◽  
Author(s):  
Toomas Silla ◽  
Andres Männik ◽  
Mart Ustav
Keyword(s):  
Transcriptional Activation ◽  
Human Herpesvirus ◽  
Bovine Papillomavirus ◽  
Transactivation Domain ◽  
Mitotic Chromosomes ◽  
Herpesvirus Type ◽  
Barr Virus ◽  
Human Herpesvirus Type ◽  
Multiple Copies ◽  
Epstein Barr

ABSTRACT Effective segregation of the bovine papillomavirus type 1 (BPV1), Epstein-Barr virus (EBV), and Kaposi's sarcoma-associated human herpesvirus type 8 (KSHV) genomes into daughter cells is mediated by a single viral protein that tethers viral genomes to host mitotic chromosomes. The linker proteins that mediate BPV1, EBV, and KSHV segregation are E2, LANA1, and EBNA1, respectively. The N-terminal transactivation domain of BPV1 E2 is responsible for chromatin attachment and subsequent viral genome segregation. Because E2 transcriptional activation and chromatin attachment functions are not mutually exclusive, we aimed to determine the requirement of these activities during segregation by analyzing chimeric E2 proteins. This approach allowed us to separate the two activities. Our data showed that attachment of the segregation protein to chromatin is not sufficient for proper segregation. Rather, formation of a segregation-competent complex which carries multiple copies of the segregation protein is required. Complementation studies of E2 functional domains indicated that chromatin attachment and transactivation functions must act in concert to ensure proper plasmid segregation. These data indicate that there are specific interactions between linker molecules and transcription factors/complexes that greatly increase segregation-competent complex formation. We also showed, using hybrid E2 molecules, that restored segregation function does not involve interactions with Brd4.

scholarly journals Inhibition of PLK1-dependent EBNA2 phosphorylation promotes lymphomagenesis in EBV-infected mice

2021 ◽  
Author(s):  
Xiang Zhang ◽  
Patrick Schuhmachers ◽  
André Mourão ◽  
Piero Giansanti ◽  
Anita Murer ◽  
...  
Keyword(s):  
B Cell ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Transactivation Domain ◽  
Healthy Human ◽  
Barr Virus ◽  
In Vivo Experiments ◽  
Epstein Barr ◽  
Apparently Healthy

ABSTRACTWhile Epstein-Barr virus (EBV) establishes a life-long latent infection in apparently healthy human immunocompetent hosts, immunodeficient individuals are at particular risk to develop lymphoproliferative B cell malignancies caused by EBV. A key EBV protein is the transcription factor EBV nuclear antigen 2 (EBNA2), which initiates B cell proliferation. Here, we combine biochemical, cellular and in vivo experiments demonstrating that the mitotic polo-like kinase 1 (PLK1) binds to EBNA2, phosphorylates its transactivation domain and thereby inhibits its biological activity. EBNA2 mutants that impair PLK1 binding or prevent EBNA2 phosphorylation are gain-of-function mutants. They have enhanced transactivation capacities, accelerate the proliferation of infected B cells and promote the development of monoclonal B cell lymphomas in infected mice. Thus, PLK1 coordinates the activity of EBNA2 to attenuate the risk of tumor incidences in favor of the establishment of latency in the infected but healthy host.

scholarly journals Distinct Domains of Erythroid Krüppel-Like Factor Modulate Chromatin Remodeling and Transactivation at the Endogenous β-Globin Gene Promoter

2002 ◽  
Vol 22 (1) ◽  
pp. 161-170 ◽  
Author(s):  
R. Clark Brown ◽  
Scott Pattison ◽  
Janine van Ree ◽  
Elise Coghill ◽  
Andrew Perkins ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Gene Transcription ◽  
Transcriptional Activation ◽  
Globin Gene ◽  
Regulatory Elements ◽  
Binding Studies ◽  
Amino Terminal ◽  
Cellular Models

ABSTRACT Characterization of the mechanism(s) of action of trans-acting factors in higher eukaryotes requires the establishment of cellular models that test their function at endogenous target gene regulatory elements. Erythroid Krüppel-like factor (EKLF) is essential for β-globin gene transcription. To elucidate the in vivo determinants leading to transcription of the adult β-globin gene, functional domains of EKLF were examined in the context of chromatin remodeling and transcriptional activation at the endogenous locus. Human EKLF (hEKLF) sequences, linked to an estrogen-responsive domain, were studied with an erythroblast cell line lacking endogenous EKLF expression (J2eΔeklf). J2eΔeklf cells transduced with hEKLF demonstrated a dose-dependent rescue of β-globin transcription in the presence of inducing ligand. Further analysis using a series of amino-terminal truncation mutants of hEKLF identified a distinct internal domain, which is sufficient for transactivation. Interestingly, studies of the chromatin structure of the β-promoter revealed that a smaller carboxy-terminal domain generated an open promoter configuration. In vitro and in vivo binding studies demonstrated that this region interacted with BRG1, a component of the SWI/SNF chromatin remodeling complex. However, further study revealed that BRG1 interacted with an even smaller domain of EKLF, suggesting that additional protein interactions are required for chromatin remodeling at the endogenous β-promoter. Taken together, our findings support a stepwise process of chromatin remodeling and coactivator recruitment to the β-globin promoter in vivo. The J2eΔeklf inducible hEKLF system will be a valuable tool for further characterizing the temporal series of events required for endogenous β-globin gene transcription.

scholarly journals Epstein-Barr Virus Nuclear Antigen 2 Binds via Its Methylated Arginine-Glycine Repeat to the Survival Motor Neuron Protein

2003 ◽  
Vol 77 (8) ◽  
pp. 5008-5013 ◽  
Author(s):  
Stephanie Barth ◽  
Michael Liss ◽  
Marc D. Voss ◽  
Thomas Dobner ◽  
Utz Fischer ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Cell Transformation ◽  
Survival Motor Neuron ◽  
Nuclear Antigen ◽  
Survival Motor Neuron Protein ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Here we provide evidence that EBNA2 is methylated in vivo and that methylation of EBNA2 is a prerequisite for binding to SMN. We present SMN as a novel binding partner of EBNA2 by showing that EBNA2 colocalizes with SMN in nuclear gems and that both proteins can be coimmunoprecipitated from cellular extract. Furthermore, in vitro methylation of either wild-type EBNA2 or a glutathione S-transferase-EBNA2 fusion protein encompassing the arginine-glycine (RG) repeat element is necessary for in vitro binding to the Tudor domain of SMN. The recently shown functional cooperation of SMN and EBNA2 in transcriptional activation and the previous observation of a severely reduced transformation potential yet strongly enhanced transcriptional activity of an EBNA2 mutant lacking the RG repeat indicate that binding of SMN to EBNA2 is a critical step in B-cell transformation by Epstein-Barr virus.

scholarly journals BZLF1 interacts with the chromatin remodeler INO80 promoting escape from latent infections with Epstein-Barr virus

2018 ◽  
Author(s):  
Marisa Schaeffner ◽  
Paulina Mrozek-Gorska ◽  
Anne Woellmer ◽  
Takanobu Tagawa ◽  
Alexander Buschle ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Nucleosome Occupancy ◽  
Dna Methyltransferases ◽  
Viral Transcription ◽  
Chromatin Remodeler ◽  
Barr Virus ◽  
Pioneer Factors ◽  
Epstein Barr

ABSTRACTA hallmark of Epstein-Barr virus (EBV) infections is its latent phase, when all viral lytic genes are repressed. Repression results from a high nucleosome occupancy and epigenetic silencing by cellular factors such as the Polycomb repressive complex 2 (PRC2) and DNA methyltransferases that respectively introduce repressive histone marks and DNA methylation. The viral transcription factor BZLF1 acts as molecular switch to induce the transition from the latent to the lytic or productive phase of EBV’s life cycle. It is unknown how BZLF1 can bind to the epigenetically silenced viral DNA and whether it directly reactivates the viral genome through chromatin remodeling. We addressed these fundamental questions and found that BZLF1 binds to nucleosomal DNA motifs bothin vivoandin vitro, a property characteristic ofbona fidepioneer factors. BZLF1 co-precipitates with cellular chromatin remodeler ATPases, and the knock-down of one of them, INO80, impaired lytic reactivation and virus synthesis. We conclude that BZLF1 reactivates the EBV genome by directly binding to silenced chromatin and recruiting cellular chromatin remodeling enzymes, which implement a permissive state for viral transcription. BZLF1 shares this mode of action with a limited number of cellular pioneer factors, which are instrumental in transcriptional activation, differentiation, and reprogramming in all eukaryotic cells.

Characterization of the Epstein–Barr virus BRRF1 gene, located between early genes BZLF1 and BRLF1

Microbiology ◽  
2000 ◽  
Vol 81 (7) ◽  
pp. 1791-1799 ◽  
Author(s):  
Carine Segouffin-Cariou ◽  
Géraldine Farjot ◽  
Alain Sergeant ◽  
Henri Gruffat
Keyword(s):  
Transcriptional Activation ◽  
Binding Sites ◽  
Epstein Barr Virus ◽  
Regulatory Elements ◽  
Barr Virus ◽  
Viral Genes ◽  
Epstein Barr

The switch from latency to a productive cycle in Epstein–Barr virus (EBV)-infected B cells proliferating in vitro is thought to be due to the transcriptional activation of two viral genes, BZLF1 and BRLF1, encoding two transcription factors called EB1 and R respectively. However, a third gene, BRRF1 is contained in the BZLF1/BRLF1 locus, overlapping with BRLF1 but in inverse orientation. We have characterized the 5′ end of the BRRF1 mRNA and the promoter, PNa, at which BRRF1 pre-mRNA is initiated. We show that although a single BRRF1 mRNA species is induced by 12-O-tetradecanoylphorbol 13-acetate/sodium butyrate in several EBV-infected B cell lines, in Akata cells treated with anti-IgG two BRRF1 mRNAs can be detected. Transcription initiated at the BRRF1 promoter was activated by EB1 but not by R, and EB1-binding sites which contribute to the EB1-activated transcription have been mapped to between positions −469 and +1. A 34 kDa protein could be translated from the BRRF1 mRNA both in vitro and in vivo, and was found predominantly in the nucleus of HeLa cells transfected with a BRRF1 expression vector. Thus there are three promoters in the region of the EBV chromatin containing the BZLF1/BRLF1 genes, two of which, PZ and PNa, potentially share regulatory elements.

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