Small Molecule, Big Prospects: MicroRNA in Pregnancy and Its Complications

Figure 1

A schematic diagram showing miRNA biogenesis and miRNA-mediated target mRNA suppression. The primary miRNAs (pri-miRNA) are transcribed from miRNA genes by RNA polymerase II or III in the nucleus and subsequently processed by Drosha and DGCR8 to form precursor miRNA (pre-miRNA). Next, the pre-miRNAs are exported into cytoplasm by exportin 5 and RanGTP. In the cytoplasm, the pre-miRNAs are further cleaved by Dicer and resulted in two ssRNAs. Finally, the ssRNAs integrate into RISC protein complex which includes Argonaute 2, Dicer, and TRBP. Functionally, the miRNA-RISC complex inhibits target mRNA expression through either translational repression or mRNA cleavage.