Figure 1.

Biogenesis and biological function of miRNAs. First, a specific miRNA gene transcribes into pri‐miRNA through polymerase II or III in the nucleus. Next, Drosha cleaved the hairpin structure of pri‐miRNA to produce pre‐miRNA which is subsequently exported to the cytoplasm by Exportin5. Then, the miRNA duplex is released after the excision of Dicer. After that, a combination of miRNA duplex and Argonaute protein forms a RNA‐induced silencing complex (RISC), in which the passenger strand of miRNA is degraded. Finally, RISC causes mRNA degradation or translational suppression by targeting the 3′‐UTR of mRNA