BJAB Cell Lines Unmodified, Transduced with ith lentiviral vector pNL-SIN-CMV-AcGFP or pNL-SIN-CMV-AcGFP/miR-K12-11

All metazoan eukaryotes express microRNAs (miRNAs), ~22 nt long regulatory RNAs that can repress the expression of mRNAs bearing complementary sequences. Several DNA viruses also express miRNAs in infected cells, suggesting a role in viral replication and pathogenesis. While specific viral miRNAs have been shown to autoregulate viral mRNAs or downregulate cellular mRNAs via novel target sites, the function of the majority of viral miRNAs remains unknown. Here, we report that the miR-K12-11 miRNA encoded by Kaposi’s Sarcoma Associated Herpesvirus (KSHV) shows significant homology to cellular miR-155, including the entire miRNA “seed” region. Using a range of assays, we demonstrate that expression of physiological levels of miRK12- 11 or miR-155 results in the downregulation of an extensive set of common mRNA targets, including genes with known roles in cell growth regulation. Our findings indicate that viral miR-K12-11 functions as an ortholog of cellular miR-155 and has likely evolved to exploit a pre-existing gene regulatory pathway in B-cells. Moreover, the known etiological role of miR-155 in B-cell transformation suggests the possibility that miR-K12-11 may contribute to the induction of KSHV positive B-cell tumors in infected patients. Keywords: miRNA stable expression comparisons BJAB cells were infected and sorted 48 hours after infection. 12 to 16 days after transduction, gene expression analysis of 10 independent BJAB cell pools, expressing AcGFP only or AcGPF and miR-K12-11, was performed using Human Operon v3.0.2 arrays. Each ample was run against Universal Human Reference RNA, Stratagene. # of Arrays: BJAB = 3 AcGFP only = 10 AcGFP miR-K12-11 = 11