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MicroRNA-155 is an Epstein-Barr Virus induced gene that modulates EBV-regulated gene expression (EBV infection)

ABSTRACT: The cellular microRNA, miR-155 has been shown to be involved in lymphocyte activation and is expressed in EBV infected cells displaying type III latency gene expression but not type I latency gene expression. We show here that the elevated levels of miR-155 in type III latency cells is due to EBV gene expression and not epigenetic differences in cell lines tested and we show that expression in EBV infected cells requires a conserved AP-1 element in the miR-155 promoter. Gene expression analysis was carried out in a type I latency cell line transduced with a miR-155 expressing retrovirus. This analysis identified both miR-155 suppressed and induced cellular mRNAs and suggested that in addition to direct targeting of 3’ UTRs, miR-155 alters gene expression in part through the alteration of signal transduction pathways. 3’ UTR reporter analysis of predicted miR-155 target genes identified the transcriptional regulatory genes, BACH1, ZIC3, HIVEP2, CEBPB, ZNF652, ARID2, and SMAD5 as miR-155 targets. Western blot analysis of the most highly suppressed of these, BACH1, showed lower expression in cells transduced with a miR-155 retrovirus. Inspection of the promoters from genes regulated in EBV infected cells and in cells infected with a miR-155 retrovirus identified potential binding sequences for BACH1 and ZIC3. Together, these experiments suggest that the induction of miR-155 by EBV contributes to EBV mediated signaling in part through the modulation of transcriptional regulatory factors. Keywords: Gene expression analysis in EBV positive vs EBV negative cells

ORGANISM(S): Homo sapiens

PROVIDER: GSE10863 | GEO | 2008/03/18

SECONDARY ACCESSION(S): PRJNA108885

REPOSITORIES: GEO

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Project description:The cellular microRNA, miR-155 has been shown to be involved in lymphocyte activation and is expressed in EBV infected cells displaying type III latency gene expression but not type I latency gene expression. We show here that the elevated levels of miR-155 in type III latency cells is due to EBV gene expression and not epigenetic differences in cell lines tested and we show that expression in EBV infected cells requires a conserved AP-1 element in the miR-155 promoter. Gene expression analysis was carried out in a type I latency cell line transduced with a miR-155 expressing retrovirus. This analysis identified both miR-155 suppressed and induced cellular mRNAs and suggested that in addition to direct targeting of 3’ UTRs, miR-155 alters gene expression in part through the alteration of signal transduction pathways. 3’ UTR reporter analysis of predicted miR-155 target genes identified the transcriptional regulatory genes, BACH1, ZIC3, HIVEP2, CEBPB, ZNF652, ARID2, and SMAD5 as miR-155 targets. Western blot analysis of the most highly suppressed of these, BACH1, showed lower expression in cells transduced with a miR-155 retrovirus. Inspection of the promoters from genes regulated in EBV infected cells and in cells infected with a miR-155 retrovirus identified potential binding sequences for BACH1 and ZIC3. Together, these experiments suggest that the induction of miR-155 by EBV contributes to EBV mediated signaling in part through the modulation of transcriptional regulatory factors. Keywords: Differential expression of miR-155 vs cntl expressing cells The EBV positive Burkitt's lymphoma cell line, Akata was infected with a control (pEhyg-miRCntl) or a microRNA-155 expressing (pEhyg-miR-155) retrovirus. Duplicate infections with the control retrovirus and with the miR-155 retrovirus were carried out. Control and miR-155 infection pair 1 were run on an array as well as a dye swap. Control and miR-155 infection pair 2 were similarly run on an array as well as a second array containing a dye swap.

Project description:The Epstein Barr virus (EBV) encoded latent membrane protein-1 (LMP1) is a functional homologue of the tumor necrosis factor receptor family and contributes substantially to the oncogenic potential of EBV through activation of Nuclear Factor-kappaB (NF-kappaB). MicroRNAs (miRNAs) are a class of small RNA molecules that are involved in the regulation of cellular processes such as growth, development, and apoptosis, and have recently been linked to cancer phenotypes. Through miRNA microarray analysis, we demonstrate that LMP1 dysregulates the expression of several cellular miRNAs, including the most highly regulated of these, miR-146a. Quantitative RT-PCR analysis confirmed induced expression of miR-146a by LMP1. Analysis of miR-146a expression in EBV latency type III and type I cell lines revealed substantial expression of miR-146a in type III (which express LMP1) but not in type I cell lines. Reporter studies demonstrated that LMP1 induces miR-146a predominantly through two NF-kappaB binding sites in the miR-146a promoter and identified a role for an OCT-1 site in conferring basal and induced expression. Array analysis of cellular mRNAs expressed in Akata cells transduced with an miR-146a expressing retrovirus identified genes that are directly or indirectly regulated by miR-146a, including a group of interferon responsive genes that are inhibited by miR-146a. Since miR-146a is known to be induced by agents that activate the interferon response pathway (including LMP1), these results suggest that miR-146a functions in a negative feedback loop to modulate the intensity and/or duration of the interferon response. Keywords: microRNA expression modified by EBV encoded oncogene, LMP1 EBV negative Mutu E1dn Cl. 3 cells were transduced with either a control retrovirus (pEhyg) or an LMP1 containing retrovirus (pEhyg-FLAG-LMP1). Cells were selected with hygromycin for approximately 2 weeks afterwhich 5 pairs of RNA preps were carried out on 5 successive days. Arrays GSM255656 and GSM255659 are dye swaps in which LMP1 samples were labeled with Cy3 and control samples were labeled with Cy5.

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MicroRNA-155 is an Epstein-Barr Virus induced gene that modulates EBV-regulated gene expression (EBV infection)

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