Project description:MicroRNAs (miRNAs) are a class of small RNA molecules previously known to function as post-transcriptional regulators in multiple cellular processes. Here, we show that a human cellular miRNA, hsa-miR-155, can regulate the latent replication origin (oriP) of Epstein-Barr virus (EBV) by competing with Epstein-Barr nuclear antigen 1 (EBNA-1) for direct binding to the dyad symmetry (DS) sequence on the oriP, and thus regulate the function of the DNA replication origin. When this direct binding was abolished by introducing a mutation into the hsa-miR-155 or DS sequence, replication resumed. Furthermore, endogenous hsa-miR-155 could target specifically to the EBV genomic replication origin in EBV type I-latently infected cells and regulate the viral DNA replication. Our discovery represents a hitherto undiscovered and important function of miRNA for the control of DNA replication, and demonstrates a probable mechanism of how this can be achieved using the latent replication origin of EBV.
Project description:RATIONALE: The Epstein Barr virus can cause cancer and lymphoproliferative disorders. Ganciclovir is an antiviral drug that acts against the Epstein Barr virus. Arginine butyrate may make virus cells more sensitive to ganciclovir. Combining ganciclovir and arginine butyrate may kill more Epstein Barr virus cells and tumor cells.
PURPOSE: Phase I trial to study the effectiveness of arginine butyrate plus ganciclovir in treating patients who have cancer or lymphoproliferative disorders that are associated with the Epstein Barr virus.
Project description:The molecular response to hypoxia is a critical cellular process implicated in cancer, and a target for drug development. The activity of the major player, HIF1M-NM-1,M-BM- is regulated at different levels, including the transcriptional level by the Ets factor ELK3. The molecular mechanisms of this intimate transcriptional connection remain largely unknown. Whilst investigating global ELK3-chromatin interactions, we uncovered an unexpected connection that involves the microRNA hsa-miR-155-5p, a hypoxia-inducible oncomir that targets HIF1M-NM-1. One of the ELK3 chromatin binding sites, detected by Chromatin Immuno-Precipitation Sequencing (ChIP-seq) of normal Human Umbilical Vein Endothelial Cells (HUVEC), is located at the transcription start site of the MIR155HG genes that expresses hsa-miR-155-5p. We confirmed that ELK3 binds to this promoter by ChIP and QPCR. We showed that ELK3 and hsa-miR-155-5p form a double-negative regulatory loop. ELK3 depletion induced hsa-miR-155-5p expression, and hsa-miR-155-5p expression decreased ELK3 expression at the RNA level through a conserved target sequence in its 3M-bM-^@M-^Y-UTR. We further showed that the activities of hsa-miR-155-5p and ELK3 are functionally linked. Pathway analysis indicates that both factors are implicated in related processes, including cancer and angiogenesis. hsa-miR-155-5p expression and ELK3 depletion have similar effects on expression of known ELK3 target genes, and in-vitro angiogenesis and wound closure. Bioinformatic analysis of cancer RNA-seq data shows that hsa-miR-155-5p and ELK3 expression are significantly anti-correlated, as would be expected from hsa-miR-155-5p targeting ELK3 RNA. Hypoxia (0% oxygen) down-regulates ELK3 mRNA in a microRNA and hsa-miR-155-5p dependent manner. These results tie ELK3 into the hypoxia response pathway through an oncogenic microRNA and into a circuit implicated in the dynamics of the hypoxic response.M-BM- This crosstalk could be important in the development of new treatments for a range of pathologies. Examination of ELK3 DNA interactions in HUVEC cells under normal oxygen conditions
Project description:The molecular response to hypoxia is a critical cellular process implicated in cancer, and a target for drug development. The activity of the major player, HIF1α, is regulated at different levels, including the transcriptional level by the Ets factor ELK3. The molecular mechanisms of this intimate transcriptional connection remain largely unknown. Whilst investigating global ELK3-chromatin interactions, we uncovered an unexpected connection that involves the microRNA hsa-miR-155-5p, a hypoxia-inducible oncomir that targets HIF1α. One of the ELK3 chromatin binding sites, detected by Chromatin Immuno-Precipitation Sequencing (ChIP-seq) of normal Human Umbilical Vein Endothelial Cells (HUVEC), is located at the transcription start site of the MIR155HG genes that expresses hsa-miR-155-5p. We confirmed that ELK3 binds to this promoter by ChIP and QPCR. We showed that ELK3 and hsa-miR-155-5p form a double-negative regulatory loop. ELK3 depletion induced hsa-miR-155-5p expression, and hsa-miR-155-5p expression decreased ELK3 expression at the RNA level through a conserved target sequence in its 3’-UTR. We further showed that the activities of hsa-miR-155-5p and ELK3 are functionally linked. Pathway analysis indicates that both factors are implicated in related processes, including cancer and angiogenesis. hsa-miR-155-5p expression and ELK3 depletion have similar effects on expression of known ELK3 target genes, and in-vitro angiogenesis and wound closure. Bioinformatic analysis of cancer RNA-seq data shows that hsa-miR-155-5p and ELK3 expression are significantly anti-correlated, as would be expected from hsa-miR-155-5p targeting ELK3 RNA. Hypoxia (0% oxygen) down-regulates ELK3 mRNA in a microRNA and hsa-miR-155-5p dependent manner. These results tie ELK3 into the hypoxia response pathway through an oncogenic microRNA and into a circuit implicated in the dynamics of the hypoxic response. This crosstalk could be important in the development of new treatments for a range of pathologies.
Project description:Epstein-Barr virus has been reported to regulate cellular microRNA expression in B cells. In the present study, we investigated the differential microRNAs modulated by Epstein-Barr virus in Naspharyngeal Carcinoma, using CapitalBio corporation's mammalian miRNA arrays. Three cellular models were used in this study: the human naspharyngeal carcinoma cell line TW03 as a blank control; TW03 transfected with Epstein-Barr virus encoded LMP1; TW03 transfected with Epstein-Barr virus encoded LMP2A
Project description:Epstein-Barr virus has been reported to regulate cellular microRNA expression in B cells. In the present study, we investigated the differential microRNAs modulated by Epstein-Barr virus in Naspharyngeal Carcinoma, using CapitalBio corporation's mammalian miRNA arrays.
2011-01-13 | GSE26596 | GEO
Project description:microRNA-155 is an Epstein-Barr Virus induced gene that modulates Epstein Barr virus regulated gene expression pathways
Project description:Marek’s disease virus 1 (MDV-1), an oncogenic -herpesvirus that induces T-cell lymphomas in chickens, serves as model system to study transformation by lymphotropic herpesviruses. Like the oncogenic human -herpesviruses Kaposi’s sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), MDV-1 encodes several viral microRNAs (miRNAs). One MDV-1 miRNA, miR-M4, shares the same “seed” targeting sequence with both a KSHV miRNA, miR-K11, and cellular miR-155. Importantly, miR-M4 plays a critical role in T-cell transformation by MDV-1, while miR-K11 and cellular miR-155 are thought to play key roles in B-cell transformation by KSHV and EBV, respectively. Here, we present an analysis of the mRNAs targeted by viral miRNAs expressed in the chicken T-cell line MSB1, which is naturally coinfected with MDV-1 and the related nonpathogenic virus MDV-2. Our analysis identified>1,000 endogenous mRNAs targeted by miRNAs encoded by each virus, many of which are targeted by both MDV-1 and MDV-2 miRNAs. We present a functional analysis of an MDV-1 gene, RLORF8, targeted by four MDV-1 miRNAs and a cellular gene, encoding interleukin-18 (IL-18) and targeted by both MDV-1 and MDV-2 miRNAs, and show that ectopic expression of either protein in a form resistant to miRNA inhibition results in inhibition of cell proliferation. Finally, we present a restricted list of 9 genes targeted by not only MDV-1 miR-M4 but also KSHV miR-K11 and human miR-155. Given the critical role played by miR-155 seed family members in lymphomagenesis in humans and chickens, these mRNA targets may contain genes whose inhibition plays a conserved role in herpesvirus transformation. PAR-CLIP experiment of MSB1 cells
Project description:Epstein-Barr virus is associated with several human malignancies, including Burkitt Lymnphoma. The virus encodes more than 40 microRNAs, which participate in its possible pathogenetic role. We used microarrays to study the effect of the expression of an Epstein-Barr virus-encoded microRNA (ebv-BART6-3p) on the global gene expression profile of Burkitt Lymphoma cell lines.
Project description:The Epstein-Barr virus (EBV) is associated with lymphoid and epithelial cancers. Initial EBV infection alters lymphocyte gene expression, inducing cellular proliferation and differentiation as the virus transitions through consecutive latency transcription programs. Cellular microRNAs (miRNAs) are important regulators of signaling pathways and are implicated in carcinogenesis. The extent to which EBV exploits cellular miRNAs is unknown. Using micro-array analysis and quantitative PCR, we demonstrate differential expression of cellular miRNAs in type III versus type I EBV latency including elevated expression of miR-21, miR-23a, miR-24, miR-27a, miR-34a, miR-146a and b, and miR-155. In contrast, miR-28 expression was found to be lower in type III latency. The EBV-mediated regulation of cellular miRNAs may contribute to EBV signaling and associated cancers. There were two major objectives for this study. The first objective was to determine whether EBV infected cells exhibiting type I latency influence cellular microRNA expression. For this study, four EBV negative derivatives of the type I latency cell line, Mutu I, were derived by retroviral infection with a dominant negative from of the EBV episomal replication factor, EBNA1. RNA from these four clones were compared to parental EBV positive Mutu I cells. Four dual labeling experiments were carried out for this comparison with dye reversal for every second pair of RNAs. The second objective was to determine whether EBV type III latency cells exhibit altered cellular microRNA gene expression compared to type I latency cells or EBV negative B cells. Four dual labeling experiments were carried out for this analysis with dye reversal for every second pair of RNAs.