Genome-wide transcription program and expression of the Rta responsive gene of Epstein–Barr virus

Abstract

Infection with Epstein-Barr virus (EBV) usually leads to a latent state in B lymphocytes. The virus can be reactivated through two viral transactivators, Zta and Rta, leading to a cascade of gene expression. An EBV DNA array was generated to analyze the pattern of transcription of the entire EBV genome under various conditions. Firstly, a complete set of temporal expression clusters of EBV genes was displayed by analyzing the array data of anti-IgG-induced Akata cells. In addition to assigning genes of unknown function to the various clusters, increasing expression of latent genes, including EBNA2, EBNA3A and EBNA 3C, was observed during virus replication. Secondly, gene expression independent of viral DNA replication was analyzed in PAA blocked Akata cells and in chemically induced Raji cells. Several genes with presumed late functions were found to be expressed with early kinetics and independent of viral DNA replication, suggesting possible novel functions for these genes. Finally, the EBV array was used to identify Rta responsive gene expression in Raji cells, and in the EBV-positive epithelial cells NA, using a Zta siRNA strategy. The array data were confirmed by Northern blotting, RT-PCR and reporter assays. All the information here thus provides a better understanding of the control of EBV lytic gene expression.

Characterization of the Uracil-DNA Glycosylase Activity of Epstein-Barr Virus BKRF3 and Its Role in Lytic Viral DNA Replication

“…4B). These data were also in accordance with our and others' previous observation in microarray analysis that BKRF3 is expressed in the second cluster of EBV early genes (42,82,83). We then detected the expression of BKRF3 in anti-IgG-induced Akata cells and Rta-transfected Raji cells (Fig.…”

“…Here we propose that EBV BKRF3 may function in addition to LMP1 to contribute to genome instability, thus favoring AID/UNG-induced c-myc/IgH translocations. In summary, although expression of BKRF3 transcripts has been observed upon induction of EBV-positive B cells and by microarray analysis of NK/T-cell lymphoproliferative cell lines (42,82,83), we demonstrated here for the first time that BKRF3 encodes a conserved and functional uracil DNA glycosylase of the UNG family. Because inhibition of both viral and cellular UDG activities results in suppression of EBV lytic DNA replication, we suggest that BKRF3 might play an important role in EBV lytic replication, particularly in terminally differentiated cells where the cellular counterpart is absent or limited in abundance.…”

“…In the process of switching, a single-stranded break needs to be introduced into the double-stranded circular-form DNA to generate a free 3Ј-hydroxyl group, serving as a primer for subsequent rolling-circle replication. UDG has been suggested to play a role in producing nicks for the initiation of rollingcircle DNA replication (10,41,42). This suggestion is partly supported by the observation in yeast that uracil is a critical source of AP sites in DNA which can be further converted into single-stranded breaks by AP endonuclease (22).…”

Activation of the ERK signal transduction pathway by Epstein–Barr virus immediate-early protein Rta

“…Although EBV typically remains latent after infection of B lymphocytes, the virus must enter a lytic cycle to produce virus particles. During the onset of the lytic cycle, the virus expresses the proteins Rta and Zta, encoded by BRLF1 and BZLF1, respectively, to activate the genes required for the viral lytic cycle (Chevallier-Greco et al, 1986;Chiu et al, 2007;Feederle et al, 2000;Granato et al, 2006;Hardwick et al, 1988;Lu et al, 2006). Although the exact means by which the EBV lytic cycle is activated in vivo is unknown, activation in vitro occurs after latently infected cells are exposed to 12-Otetradecanoylphorbol-13-acetate (TPA), calcium ionophores, transforming growth factor (TGF)-b1 or anti-IgG (Daibata et al, 1990; Faggioni et al, 1986;zur Hausen et al, 1978).…”

NF-κB-Mediated Modulation of Inducible Nitric Oxide Synthase Activity Controls Induction of the Epstein-Barr Virus Productive Cycle by Transforming Growth Factor Beta 1

“…It has been shown that EBV reactivation of Akata cells leads to induction of expression of latent genes (25,49), including the LMP1 EBV oncogene. In TGF-␤1-treated Mutu-I cells, no LMP1 expression occurred, showing that NF-B activation did not come from LMP1 signaling.…”