Project description:The Epstein-Barr Virus (EBV) Nuclear Antigen 1 (EBNA1) protein is required for the establishment of EBV latent infection in proliferating B-lymphocytes. EBNA1 is a multifunctional DNA-binding protein that stimulates DNA replication at the viral origin of plasmid replication (OriP), regulates transcription of viral and cellular genes, and tethers the viral episome to the cellular chromosome. EBNA1 also provides a survival function to B-lymphocytes, potentially through its ability to alter cellular gene expression. Chromatin-immunoprecipitation (ChIP) combined with massively parallel deep-sequencing (ChIP-Seq) was used to identify cellular sites bound by EBNA1. Sites identified by ChIP-Seq were validated by conventional real-time PCR, and ChIP-Seq provided quantitative, high-resolution detection of the known EBNA1 binding sites on the EBV genome at OriP and Qp. We identified at least one cluster of unusually high-affinity EBNA1 binding sites on chromosome 11, between the divergent FAM55D and FAM55B genes. A consensus for all cellular EBNA1 binding sites is distinct from those derived from the known viral binding sites, suggesting that some of these sites are indirectly bound by EBNA1. We conclude that EBNA1 can interact with a large number of cellular genes and chromosomal loci in latently infected cells, but that these sites are likely to represent a complex ensemble of direct and indirect EBNA1 binding sites. Study of Epstein-Barr virus (EBV)
Project description:Epstein-Barr virus (EBV) is a ubiquitous gammaherpes virus that establishes a life-long latency in over 90% of the world's population. Epstein Barr Nuclear Antigen 1, EBNA1, is the only viral protein consistently detected in all viral latency programs, as well as in all forms of EBV-associated malignancies. EBNA1 plays critical roles in the viral life cycle by fostering the replication and maintenance of the extrachromosomal viral genome as well as enhancing transcription from multiple viral promoters. Using chromatin immunoprecipitation and human promoter microarrays (an analysis termed ChIP-chip) we found that EBNA1 binds site specifically within multiple human promoters. To determine whether EBNA1’s binding to these promoters perturbed gene expression, we measured the levels of cellular mRNAs by microarrays when EBNA1 was inhibited by a dominant negative derivative of EBNA1 (DomNeg1). Keywords: viral regulation of cellular genes
Project description:The Epstein-Barr Virus (EBV) Nuclear Antigen 1 (EBNA1) protein is required for the establishment of EBV latent infection in proliferating B-lymphocytes. EBNA1 is a multifunctional DNA-binding protein that stimulates DNA replication at the viral origin of plasmid replication (OriP), regulates transcription of viral and cellular genes, and tethers the viral episome to the cellular chromosome. EBNA1 also provides a survival function to B-lymphocytes, potentially through its ability to alter cellular gene expression. Chromatin-immunoprecipitation (ChIP) combined with massively parallel deep-sequencing (ChIP-Seq) was used to identify cellular sites bound by EBNA1. Sites identified by ChIP-Seq were validated by conventional real-time PCR, and ChIP-Seq provided quantitative, high-resolution detection of the known EBNA1 binding sites on the EBV genome at OriP and Qp. We identified at least one cluster of unusually high-affinity EBNA1 binding sites on chromosome 11, between the divergent FAM55D and FAM55B genes. A consensus for all cellular EBNA1 binding sites is distinct from those derived from the known viral binding sites, suggesting that some of these sites are indirectly bound by EBNA1. We conclude that EBNA1 can interact with a large number of cellular genes and chromosomal loci in latently infected cells, but that these sites are likely to represent a complex ensemble of direct and indirect EBNA1 binding sites.
Project description:Epstein-Barr virus (EBV) is a ubiquitous gammaherpes virus that establishes a life-long latency in over 90% of the world's population. Epstein Barr Nuclear Antigen 1, EBNA1, is the only viral protein consistently detected in all viral latency programs, as well as in all forms of EBV-associated malignancies. EBNA1 plays critical roles in the viral life cycle by fostering the replication and maintenance of the extrachromosomal viral genome as well as enhancing transcription from multiple viral promoters. Using chromatin immunoprecipitation and human promoter microarrays (an analysis termed ChIP-chip) we found that EBNA1 binds site specifically within multiple human promoters. To determine whether EBNA1â??s binding to these promoters perturbed gene expression, we measured the levels of cellular mRNAs by microarrays when EBNA1 was inhibited by a dominant negative derivative of EBNA1 (DomNeg1). Keywords: viral regulation of cellular genes We analysed mRNA expression from the EBV-positive lymphoblastoid cell line 721 transduced with either a control (empty) retroviral vector or a DomNeg1-encoding retroviral vector. For ChIP-chip, DNA from immunoprecipitated chromatin using a anti-EBNA1 antibody (IH4) along with total chromatin was hybridized to a Nimblegen human promoter arrays (CHAR0150-HP2). A single ChIP-chip experiment was performed with DNAs pooled equally from three independent ChIP experiments.
Project description:EBNA1 is the EBV-encoded nuclear antigen required for viral episome maintenance during latency. EBNA1 is a sequence specific DNA binding protein with high affinity binding sites for the viral genome, especially OriP. EBNA1 can also bind sequence specifically to a large number of sites in the host cellular genome, but the function of these binding sites has remained elusive. EBNA1 is also known to provide a host cell survival function, but the molecular mechanisms accounting for this function are not completely understood. Here, we show by integrating ChIP-Seq and RNA-Seq with experimental validation that MEF2B, IL6R, and EBF1 are high confidence target genes of EBNA1 that are essential for viability of B-lymphocytes latently infected with EBV. We show that EBNA1 binds to ~1000 sites with many, but not all, universally bound in different cell types, including Burkitt lymphoma (BL) and nasopharyngeal carcinoma (NPC). We find that a large subset of EBNA1 binding sites are located proximal to transcription start sites and correlate genome-wide with transcription activity. EBNA1 bound to genes of high significance for B-cell growth and function, including MEF2B, IL6R, EBF1, RNF145, POU2F1, KDM4C, FGR, EGFR, LAIR, CDC7, CD44, and IL17A. EBNA1 depletion from latently infected LCLs results in the loss of cell proliferation, and the loss of gene expression for some EBNA1-bound genes, including MEF2B, EBF1, and IL6R. Depletion of MEF2B, EBF1, or IL6R partially phenocopies EBNA1-depletion by decreasing EBV-positive cell growth and viability. These findings indicate that EBNA1 binds to a large cohort of cellular genes important for cell viability, and implicates EBNA1 as a master coordinator of host cell gene expression important for enhanced survival of latently infected cells. Examination of EBNA1 binding in Raji, MutuI, LCL and C666-1 cells and EBNA1 knockdown effect on mRNA gene expression in LCL
Project description:Latent Epstein-Barr Virus (EBV) infection promotes cancers derived from B-lymphocytes and epithelial cells. EBV-encoded nuclear antigen 1 (EBNA1) is uniformly expressed in EBV-associated cancers. The MUC1 gene evolved in mammals to protect barrier tissues from viral infections. We report that MUC1 and the encoded oncogenic MUC1-C protein are upregulated in EBV-associated gastric cancers (EBVaGCs). We demonstrate that EBNA1 forms a complex with MUC1-C that regulates EBNA1 and MUC1-C expression. EBNA1 appropriates MUC1-C for (i) inducing DNA methyltransferases and DNA methylation, (ii) suppressing p21 and driving cell cycle progression, (iii) increasing survivin in promoting survival, and (iv) regulating MYC as an effector of EBV latency. MUC1-C thereby functions in maintaining EBV episomes and regulating EBV latency and lytic genes. In regard to EBVaGC progression, MUC1-C regulates expression of the SOX2 and NOTCH1-3 stemness genes, self-renewal capacity, and tumorigenicity. These findings indicate that EBNA1 co-opts MUC1-C functions that promote EBV latency and that MUC1-C is necessary for EBVaGC pathogenesis.
Project description:The Epstein-Barr virus nuclear antigen 2 (EBNA2) initiates and maintains the proliferation of infected B cells. In search of additional cellular strategies, that control EBNA2 function, we have performed a label-free mass spectrometry-based quantification of cellular proteins in EBNA2 immuno-precipitates and found polo-like kinase 1 (PLK1) to be bound to EBNA2. EBNA2/PLK1 complex formation is strongly enforced by EBNA2 S379 phosphorylation catalyzed by the mitotic CYCLIN B/CDK1 complex.