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: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.
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: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) genomes persist in latently infected cells as extrachromosomal plasmids that attach to host chromosomes through the tethering functions of EBNA1, a viral encoded sequence-specific DNA binding protein. Here we employed circular chromosome conformation capture (4C) analysis to identify genomewide associations between EBV episomes and host chromosomes. We found that EBV episomes in Burkitt lymphoma (BL) cells preferentially associate with EBNA1 sequence-specific DNA binding sites in the cellular genome that are also enriched for B-cell factors EBF1 and RBP-jK, the repressive histone mark H3K9me3, and surrounded by AT-rich sequence. These attachment sites corresponded to transcriptionally silenced genes with enrichment in neuronal function. Depletion of EBNA1 from EBV latently infected BL cells led to a transcriptional de-repression of these silenced genes. EBV attachment sites in lymphoblastoid cells (LCLs) showed different correlations, suggesting that latency types are functionally linked to the epigenetic environment of host chromosome attachment sites.
Project description:Gene expression programs depend on sequence-specific DNA binding transcription factors, but the mechanisms that control the selective binding of these factors in a chromosomal and genomic context remain enigmatic. Here, we show that two master regulators of B-cell fate, namely EBF1 and RBP-jk, show variable genome-wide chromosome distribution in two related B-lymphocyte lines carrying different forms of Epstein-Barr Virus (EBV) latency. The latency-type specific EBV-encoded EBNA2 colocalized with RBP-jk and EBF1 at induced binding sites. Colocalization of EBF1, RBP-jk, and EBNA2 correlated with transcriptional activation. Conditional expression or repression of EBNA2 lead to a rapid alteration in RBP-jk and EBF1 binding. Biochemical and shRNA depletion studies provide evidence for cooperative assembly at co-occupied sites. These findings reveal that non-DNA binding cofactors can facilitate combinatorial interactions to induce new patterns of transcription factor occupancy and gene programming Examination of EBNA2/EBF1/EBP-jk binding in MutuI and LCL cell lines
Project description:Gene expression programs depend on sequence-specific DNA binding transcription factors, but the mechanisms that control the selective binding of these factors in a chromosomal and genomic context remain enigmatic. Here, we show that two master regulators of B-cell fate, namely EBF1 and RBP-jk, show variable genome-wide chromosome distribution in two related B-lymphocyte lines carrying different forms of Epstein-Barr Virus (EBV) latency. The latency-type specific EBV-encoded EBNA2 colocalized with RBP-jk and EBF1 at induced binding sites. Colocalization of EBF1, RBP-jk, and EBNA2 correlated with transcriptional activation. Conditional expression or repression of EBNA2 lead to a rapid alteration in RBP-jk and EBF1 binding. Biochemical and shRNA depletion studies provide evidence for cooperative assembly at co-occupied sites. These findings reveal that non-DNA binding cofactors can facilitate combinatorial interactions to induce new patterns of transcription factor occupancy and gene programming
Project description:Gene expression programs depend on sequence-specific DNA binding transcription factors, but the mechanisms that control the selective binding of these factors in a chromosomal and genomic context remain enigmatic. Here, we show that two master regulators of B-cell fate, namely EBF1 and RBP-jk, show variable genome-wide chromosome distribution in two related B-lymphocyte lines carrying different forms of Epstein-Barr Virus (EBV) latency. The latency-type specific EBV-encoded EBNA2 colocalized with RBP-jk and EBF1 at induced binding sites. Colocalization of EBF1, RBP-jk, and EBNA2 correlated with transcriptional activation. Conditional expression or repression of EBNA2 lead to a rapid alteration in RBP-jk and EBF1 binding. Biochemical and shRNA depletion studies provide evidence for cooperative assembly at co-occupied sites. These findings reveal that non-DNA binding cofactors can facilitate combinatorial interactions to induce new patterns of transcription factor occupancy and gene programming
Project description:The Epstein-Barr virus (EBV) switches between latent and lytic phases in hosts that are important in developing related diseases. However, the underlying mechanism of how the viral latent-lytic switch is controlled and how EBV itself mediates this regulation remains largely unknown. This study identified the upregulated histone acetyl reader bromodomain-containing protein 7 (BRD7) during EBV latent infection. Based on the ChIP-sequencing of endogenous BRD7 in Burkitt lymphoma cells, we found that EBV drove BRD7 to regulate cellular and viral genomic loci, including the transcriptional activation of c-Myc, a recently reported regulator of EBV latency. Additionally, EBV-mediated BRD7 signals enriched around the FUSE site in chromosome 8, and the enhancer LOC108348026 in the lgH locus, which might activate the c-Myc alleles. Mechanically, EBV-encoded nuclear antigen 1 (EBNA1) bound and recruited BRD7 to colocalize at promotor regions of the related genes, thus serving as cofactors for the maintenance of viral latency. Moreover, the disruption of BRD7 decreased the c-Myc expression, induced the BZLF1 expression, and reactivated the lytic cycle. Our findings reveal the unique role of BRD7 hijacked by EBV in maintaining the viral latency state via chromatin remodeling. The study paved the way for understanding the new molecular mechanism of EBV-induced chromatin remodeling and latent-lytic switch regulation, providing novel therapeutic candidate targets for EBV persistent infection. With establishing persistent infection in most human hosts, EBV is usually at a latent infection state. How the viral latency is maintained in cells remains largely unknown. c-Myc was recently reported to act as a controller of the lytic switch, while whether and how EBV regulates it remains to be explored. Here, we identified that BRD7 is involved in controlling EBV latency. We found that EBV-mediated BRD7 was enriched in both the normal promoter regions and the translocation alleles of c-Myc, and the disruption of BRD7 decreased c-Myc expression to reactivate the lytic cycle. We also demonstrated that EBV-encoded EBNA1 bound to and regulated BRD7. Therefore, we reveal a novel mechanism by which EBV can regulate its infection state by hijacking host BRD7 to target c-Myc. Our findings will help future therapeutic intervention strategies of EBV infection and pathogenesis.
Project description:Epstein-Barr Virus (EBV) immortalizes resting B-lymphocytes through a highly orchestrated process involving extensive reprogramming of host transcription and metabolism. Here, we use multiple omics-based approaches concurrently across the time course of B-cell infection to investigate the underlying mechanisms that control EBV-induced B-cell immortalization. ATAC-seq revealed that over a third of accessible chromatin is altered with the most perturbed sites overlapping Ets-family, including PU.1 and RUNX1 transcription factors. EBV nuclear antigens (EBNAs) clustered with different gene categories and RNA-seq identified the transcriptional response of these gene. Focusing on EBNA1 revealed a selection of gene targets involved in nucleotide metabolism. Metabolomics indicated that adenosine and purine metabolism are significantly altered by EBV immortalization, and we validated that adenosine deaminase (ADA) is a direct and critical target of EBNA1 and the EBV-directed immortalization process. These findings reveal that purine metabolism and ADA inhibitors may be a useful therapeutic for EBV-driven lymphoid cancers