R9AP is a functional receptor for Epstein-Barr virus infection in both epithelial cells and B cells
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ABSTRACT: Epstein-Barr virus (EBV), also known as the first human tumor virus, is linked to nearly 200,000 new cancer cases and millions of non-malignant diseases per year. EBV infects both human epithelial cells and B cells, several virally encoded glycoproteins define tropism and mediate a complicated entry process. Here, we showed that R9AP silencing, genetic knockout or antibody blocking significantly inhibits EBV infection in both epithelial and B cells, while R9AP overexpression promoted EBV infection, establishing this protein as a previously unidentified, essential entry receptor for EBV. Mechanistically, R9AP directly binds to EBV glycoprotein gH/gL to mediate membrane fusion. Importantly, the interaction of R9AP with gH/gL was inhibited by the competition of AMMO1, a highly potent anti-gH/gL neutralizing antibody blocking EBV infection of both Epithelial cells and B cells. Further, treatment with an R9AP peptide encompassing the gH/gL binding site inhibited EBV infection in vitro and reduced viral loads in EBV infected humanized mice. Altogether, we proposed R9AP as the first characterized common cellular receptor for EBV infection of the major cell types and could serve as a potential target for novel interventional strategies.
Project description:<p>Following infection of B cells, Epstein Barr virus (EBV) engages host pathways that mediate cell proliferation and transformation, contributing to the propensity of the virus to drive immune dysregulation and lymphomagenesis. We found that the EBV protein EBNA2 initiates NAD <em>de novo</em> biosynthesis by driving expression of the host metabolic enzyme IDO1. Virus-enforced NAD production sustained mitochondrial complex I activity, to match ATP-production with bioenergetic requirements of proliferation and transformation. In transplant patients, IDO1 expression in EBV-infected B cells, and a serum signature of increased IDO1 activity, preceded development of lymphoma. In humanized mice infected with EBV, IDO1 inhibition reduced both viremia and lymphomagenesis. Virus-orchestrated NAD biosynthesis is thus a druggable metabolic vulnerability of EBV-driven B cell transformation – opening therapeutic possibilities for EBV-related diseases.</p>
Project description:Soluble ectodomains of Epstein Barr Virus glycoproteins gH/gL and gp42 were expressed in HEK293F cells for structural characterization by cryo electron microscopy. The purified material was additionally analyzed by LC-MS/MS after digestion with trypsin or chymotrypsin to identify N-linked glycosylation from EThcD glycopeptide fragmentation spectra.
Project description:Our newly developed high-throughput screening assay of bioactive compounds discovered a cellular phosphatase, calcineurin, was critical in the regulation of Varicella-Zoster Virus (VZV) glycoprotein complex gB/gH-gL mediated cell fusion. To better understand how calcineurin regulates fusion, the potential substrates for calcineurin phosphatase were investigated in human melanoma MeWo cells upon treatment with specific calcineurin phosphatase inhibitor, pimecrolimus. Phosphopeptide enrichment and Orbitrap mass spectrometry analysis identified seven proteins that were exclusively phosphorylated in MeWo cells treated with pimecrolimus compared to DMSO vehicle control, including two known calcineurin substrates. The other five proteins were novel targets for calcineurin dephosphorylation. These data implicated that one or more of these seven proteins in the calcineurin mediated regulation of VZV gB/gH-gL mediated cell fusion.
Project description:Idiopathic pulmonary fibrosis (IPF) is a refractory and lethal interstitial lung disease characterized by alveolar epithelial cells apoptosis, fibroblast proliferation and extra-cellular matrix proteins deposition. Epstein - Barr virus (EBV) has previously been localised to alveolar epithelial cells of IPF patients. In this study we utilised a microarray based differential gene expression analysis strategy to identify potential molecular drivers of EBV associated lung fibrosis. We employed an alveolar epithelial cell line infected with EBV (A-Akata). Lytic phase infection induced in the A-Akata cells by TPA/BA treatment resulted in increase of TGFbeta1 and TIEG1 mRNA expression. Treatment of the A-Akata cells with ganciclovir, resulted in a down regulation of both TIEG1 and TGFbeta1 expression, accompanied by a suppression of the EBV early response genes, Rta and Zta. This suppression of cell turnover mediators was correlated with an increase in cell activity index. To identify a possible role for Rta in driving apoptotic gene expression, we inhibited the Rta gene expression by silencing RNA, resulting in a decrease in TGFbeta1 and TIEG1 expression. This study identifies an apoptotic role of the EBV early response genes, as enhancer factors of TIEG1 and TGFbeta1 in EBV infected alveolar epithelial cells, potentially providing a possible mechanism for the role of EBV infection in pulmonary fibrosis. Keywords: EBV lytic phase infection, epithelial cell apoptosis, oligonucleotide array analysis
Project description:Extensive DNA methylation in promoter regions is observed in gastric cancer with Epstein-barr virus (EBV) infection and EBV infection is the cause to induce this extensive hypermethylaiton phenotype in gastric epithelial cells. From transcriptome analysis, we found that TET2, one of the demethylase enzymes, was downregulated by EBV infection in gastric epithelial cell line MKN7. TET2 was overexpressed in a gastric epithelial cell line, GES1, to see its function and the hydroxymethylation, a byproduct of DNA demethylation, acquired genes by TET2 overexpression and methylation acquired genes by EBV infection were significantly overlapped. These suggested that hydroxymethylation by TET2 could function to keep unmethylated status of genes before EBV infection, and TET2 depression could contribute to methylation acquisition of these target genes after EBV infection.
Project description:Human cytomegalovirus infects multiple cell types, including fi- broblasts and epithelial cells. It penetrates fibroblasts by fusion at the cell surface but is endocytosed into epithelial cells. In this report, we demonstrate by electron microscopy that the virus uses two different routes to enter retinal pigmented epithelial cells, depending on the cell type in which the infecting virus was produced. Virus produced in epithelial cells preferentially fuses with the plasma membrane, whereas fibroblast-derived virus mostly enters by receptor-mediated endocytosis. Treatment of epithelial cells with agents that block endosome acidification inhibited infection by virus produced in fibroblasts but had only a modest effect on infection by virus from epithelial cells. Epithelial cell-generated virions had higher intrinsic ‘‘fusion-from-without’’ activity than fibroblast-generated particles, and the two virus preparations triggered different cellular signaling responses, as evidenced by markedly different transcriptional profiles. We propose that the cell type in which a human cytomegalovirus particle is produced likely influences its subsequent spread and its contribution to pathogenesis. Keywords: cell type comparison, viral infection, cell tropism, viral entry
Project description:Epstein-Barr virus (EBV) has a lifelong latency period after initial infection. Rarely, however, when the EBV immediate early gene BZLF1 is expressed by a specific stimulus, the virus switches to the lytic cycle to produce progeny viruses. We found that EBV infection reduced levels of various ceramide species in gastric cancer cells. As ceramide is a bioactive lipid implicated in the infection of various viruses, we assessed the effect of ceramide on the EBV lytic cycle. Treatment with C6-ceramide (C6-Cer) induced an increase in the endogenous ceramide pool and increased production of the viral product as well as BZLF1 expression. Treatment with the ceramidase inhibitor ceranib-2 induced EBV lytic replication with an increase in the endogenous ceramide pool. The glucosylceramide synthase inhibitor Genz-123346 inhibited C6-Cer-induced lytic replication. C6-Cer induced ERK1/2 and CREB phosphorylation, c-JUN expression, and accumulation of the autophagosome marker LC3B. Treatment with MEK1/2 inhibitor U0126 or autophagy initiation inhibitor 3-MA suppressed C6-Cer-induced EBV lytic replication. In contrast, the autophagosome-lysosome fusion inhibitor chloroquine induced BZLF1 expression. Transfection with siCREB reduced ERK1/2 phosphorylation and C6-Cer-induced BZLF1 expression. On the other hand, siJUN transfection did not affect BZLF1 expression. Our results show that increased endogenous ceramide and glycosyl ceramide (GlyCer) following C6-Cer treatment induce EBV lytic replication in gastric cancer cells via ERK1/2 and CREB phosphorylation and autophagosome accumulation.
Project description:Whether the human tumor virus, Epstein-Barr virus (EBV) promotes breast cancers remains controversial and a potential mechanism has remained elusive. Here we show EBV can infect primary mammary epithelial cells (MECs) that express the attachment receptor, CD21. EBV infection leads to the expansion of early MEC progenitor cells with a stem cell phenotype and enforces a differentiation block. When MECs were implanted as xenografts, EBV infection cooperated with activated Ras and accelerated the formation of breast cancer. Infection in EBV-related tumors was of a latency type II pattern, including expression of latent membrane proteins 1 (LMP1) and 2 (LMP2), similar to nasopharyngeal carcinoma (NPC). A human gene expression signature for EBVness was generated based on the RNA expression profile of the EBV infected primary mammary epithelial cells, tumors. This was signature associated with high grade (40 vs 13.5%) estrogen-receptor-negative status (31.8 vs. 10.5%, p53 mutation (37.5 vs 14.5%) and poor survival. In 11/33 (33%) of tumors positive for EBVness EBV-DNA was found in tumor cells by fluorescent in situ hybridization for the viral LMP1 and BXLF2 genes, while only 4/36 (11%) of EBVness-negative tumors tested positive for EBV DNA. An analysis of the TCGA breast cancer data revealed a correlation of EBVness with presence of the APOBEC mutational signatures consistent with past viral infection. We conclude that a contribution of EBV to breast cancer etiology via a ‘hit-and-run’ mechanism is plausible, in which EBV infection predisposes mammary epithelial cells to malignant transformation, but is not required for the maintenance of the malignant phenotype.
Project description:Idiopathic pulmonary fibrosis (IPF) is a refractory and lethal interstitial lung disease characterized by alveolar epithelial cells apoptosis, fibroblast proliferation and extra-cellular matrix proteins deposition. Epstein - Barr virus (EBV) has previously been localised to alveolar epithelial cells of IPF patients. In this study we utilised a microarray based differential gene expression analysis strategy to identify potential molecular drivers of EBV associated lung fibrosis. We employed an alveolar epithelial cell line infected with EBV (A-Akata). Lytic phase infection induced in the A-Akata cells by TPA/BA treatment resulted in increase of TGFbeta1 and TIEG1 mRNA expression. Treatment of the A-Akata cells with ganciclovir,; resulted in a down regulation of both TIEG1 and TGFbeta1 expression, accompanied by a suppression of the EBV early response genes, Rta and Zta. This suppression of cell turnover mediators was correlated with an increase in cell activity index. To identify a possible role for Rta in driving apoptotic gene expression, we inhibited the Rta gene expression by silencing RNA, resulting in a decrease in TGFbeta1 and TIEG1 expression. This study identifies an apoptotic role of the EBV early response genes, as enhancer factors of TIEG1 and TGFbeta1 in EBV infected alveolar epithelial cells, potentially providing a possible mechanism for the role of EBV infection in pulmonary fibrosis. Experiment Overall Design: RNA isolation, cDNA synthesis, in vitro transcription and microarray analysis of A549, EBV infected A549 (AAKata) and A549 +TGFbeta1 10ng/ml 4hours were performed as previously reported. All analysis were microarrayed in duplicate. Image files were obtained through Affymetrix GeneChip software (MAS5). Subsequently robust multichip analysis (RMA) was performed. Expression data was compared to control by ANOVA analysis, p<0.05 correlated values and a signal log ratio of 0.6 or greater (equivalent to a fold change in expression of 1.5 or greater) were taken to identify significant differential regulation. All the SLRs data resulting from the comparative analyses were reported in a graph to determine the reliability of the assay and the linearity by r2. For all the microarray assays r2 value was higher than 0.98. Using gene expression values normalised by RMA, Average Linkage Hierarchical Cluster Analysis was performed and the results visualized by TreeView software.
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.