Human Cytomegalovirus RNA2.7 Is Required for Upregulating Multiple Cellular Genes To Promote Cell Motility and Viral Spread Late in Lytic Infection.

Long noncoding RNAs (lncRNAs) are frequently associated with broad modulation of gene expression and thus provide the cell with the ability to synchronize entire metabolic processes. We used transcriptomic approaches to investigate whether the most abundant human cytomegalovirus-encoded lncRNA, RNA2.7, has this characteristic. By comparing cells infected with wild-type virus (WT) to cells infected with RNA2.7 deletion mutants, RNA2.7 was implicated in regulating a large number of cellular genes late in lytic infection. Pathway analysis indicated that >100 of these genes are associated with promoting cell movement, and the 10 most highly regulated of these were validated in further experiments. Morphological analysis and live cell tracking of WT- and RNA2.7 mutant-infected cells indicated that RNA2.7 is involved in promoting the movement and detachment of infected cells late in infection, and plaque assays using sparse cell monolayers indicated that RNA2.7 is also involved in promoting cell-to-cell spread of virus. Consistent with the observation that upregulated mRNAs are relatively A+U-rich, which is a trait associated with transcript instability, and that they are also enriched in motifs associated with mRNA instability, transcriptional inhibition experiments on WT- and RNA2.7 mutant-infected cells showed that four upregulated transcripts lived longer in the presence of RNA2.7. These findings demonstrate that RNA2.7 is required for promoting cell movement and viral spread late in infection and suggest that this may be due to general stabilization of A+U-rich transcripts. In addition to messenger RNAs (mRNAs), the human genome encodes a large number of long noncoding RNAs (lncRNAs). Many lncRNAs that have been studied in detail are associated with broad modulation of gene expression and have important biological roles. Human cytomegalovirus, which is a large, clinically important DNA virus, specifies four lncRNAs, one of which (RNA2.7) is expressed at remarkably high levels during lytic infection. Our studies show that RNA2.7 is required for upregulating a large number of human genes, about 100 of which are associated with cell movement, and for promoting the movement of infected cells and the spread of virus from one cell to another. Further bioinformatic and experimental analyses indicated that RNA2.7 may exert these effects by stabilizing mRNAs that are relatively rich in A and U nucleotides. These findings increase our knowledge of how human cytomegalovirus regulates the infected cell to promote its own success.