Role of MicroRNA-1 in Human Cancer and Its Therapeutic Potentials

Figure 1

Biological principles of miRNA (miR). miR genes are transcribed by RNA polymerase II (Pol II) to generate the primary transcripts (pri-miRNAs). The following step is mediated by the Drosha complex that generates ~65 nucleotide (nt) precursor-miRs (pre-miRNAs). Pre-miR has a short stem plus a ~2-nt 3′ overhang, which is recognized by the nuclear export factor exportin 5. On export from the nucleus, the cytoplasmic RNase III Dicer catalyzes the second processing (dicing) step to produce miR duplexes. One strand of the duplex pre-miR remains as the mature miR, whereas the other strand is degraded. Dicer and Argonaute mediate the processing of pre-miR and the miR mature strand is then assembled into the RNA-induced silencing complex (RISC) and targets the complementary mRNA 3′-UTR sequences via translational repression or mRNA cleavage.