The Influence of Host miRNA Binding to RNA Within RNA Viruses on Virus Multiplication

Abstract

microRNAs (miRNAs), non-coding RNAs about 22 nt long, regulate the post-transcription expression of genes to influence many cellular processes. The expression of host miRNAs is affected by virus invasion, which also affects virus replication. Increasing evidence has demonstrated that miRNA influences RNA virus multiplication by binding directly to the RNA virus genome. Here, the knowledge relating to miRNAs' relationships between host miRNAs and RNA viruses are discussed.

Keywords: RISC complex; RNA virus; argonaute2; flavivirus; miRNA.

Figure 1

The process of miRNA formation. The miRNA genes are transcribed for pri-miRNA by polymerase II or polymerase III; then, Drosha and DGCR8 split the pri-miRNA to form SL pre-miRNA, transferred to the cytoplasm by the export receptor, exportin-5. Next, the TL element of pre-miRNA is cut off by Dicer and TRBP to produce miRNA duplex. The miRNA duplex is transferred to RLC constituted by AGO, Dicer, TRBP, and so on and is then unfastened twice. The end, mature single-stranded miRNA enters RISC, and AGO of RISC recruits downstream factors to perform RNA interference.

Figure 2

A molecular understanding of miRNA-mediated gene silencing. When the miRNA sequences are partly complementary to the targeted RNA sequences, the AGO protein binds to GW182; then, the complex recruits PABP, CCR4 NOT, and PAN2-PAN3 to interferences’ ribosome movement on the mRNA/viral RNA (vRNA) or prevents the binding of ribosomal large and small subunits to inhibit translation. When the miRNA sequences are perfect complementary to the targeted RNA sequences, cleaving-miRISC composed of miRNA and AGO protein cuts and degrades the targeted transfer RNA to inhibit translation.

Figure 3

The process of miRNA directly binding to viral RNA.