Proteomics and Transcriptomics of BJAB Cells Expressing the Epstein-Barr Virus Noncoding RNAs EBER1 and EBER2.

In Epstein-Barr virus (EBV) latent infection, the EBV-encoded RNAs EBER1 and EBER2 accumulate in the host cell nucleus to ~10(6) copies. While the expression of EBERs in cell lines is associated with transformation, a mechanistic explanation of their roles in EBV latency remains elusive. To identify EBER-specific gene expression features, we compared the proteome and mRNA transcriptome from BJAB cells (an EBV-negative B lymphoma cell line) stably transfected with an empty plasmid or with one carrying both EBER genes.

Noncoding RNPs of viral origin.

Like their host cells, many viruses produce noncoding (nc)RNAs. These show diversity with respect to time of expression during viral infection, length and structure, protein-binding partners and relative abundance compared with their host-cell counterparts. Viruses, with their limited genomic capacity, presumably evolve or acquire ncRNAs only if they selectively enhance the viral life cycle or assist the virus in combating the host's response to infection.

Epstein-Barr virus noncoding RNAs are confined to the nucleus, whereas their partner, the human La protein, undergoes nucleocytoplasmic shuttling.

The Epstein-Barr virus (EBV) noncoding RNAs, EBV-encoded RNA 1 (EBER1) and EBER2, are the most abundant viral transcripts in all types of latently infected human B cells, but their function remains unknown. We carried out heterokaryon assays using cells that endogenously produce EBERs to address their trafficking, as well as that of the La protein, because EBERs are quantitatively bound by La in vivo. Both in this assay and in oocyte microinjection assays, EBERs are confined to the nucleus, suggesting that their contribution to viral latency is purely nuclear.

Multiple domains of EBER 1, an Epstein-Barr virus noncoding RNA, recruit human ribosomal protein L22.

EBER 1, a small noncoding viral RNA abundantly expressed in all cells transformed by Epstein-Barr virus (EBV), has been shown to associate with the human ribosomal protein L22. Here we present in vitro binding studies using purified RNAs and recombinant proteins. Electrophoretic mobility-shift assays (EMSAs) show that recombinant L22 (rL22) and maltose-binding protein (MBP)-tagged L22 protein bind EBER 1 in vitro, both forming three specific protein-dependent mobility shifts.