The functions of herpesvirus-encoded microRNAs

Abstract

Bioinformatic and direct cloning approaches have led to the identification of over 100 novel miRNAs expressed in DNA viruses, although the function of the majority of these small regulatory RNA molecules is unclear. Recently, a number of reports have now identified potential targets of viral miRNAs, including cellular and viral genes as well as an ortholog of an important immuno-regulatory cellular miRNA. In this review, we will cover the identification and characterization of miRNAs expressed in the herpesvirus family and discuss the potential significance of their role in viral infection.

Fig. 1

Proposed functions of herpesvirus miRNAs. Recent reports have identified a number of potential targets for viral miRNAs. In HSV-1,miR-LAT was reported to block apoptosis by targeting the cellular transcripts encoding TGFβ and SMAD3 [4]. HCMV miR-UL112-1 has been reported to target both the viral transactivator IE72 and the cellular immune ligand MICB [3,7]. In KSHV multiple miRNAs were found to target THBS-1. miR-K12-11 of KSHV was also identified as an ortholog of the important immunoregulatory miRNA miR-155 [6,8]. In EBV, miRNAs from the BART region were found to efficiently target expression of the oncogenic latency gene LMP1 [5]