Figure 1.

The process of miRNA expression and function: miRNA-encoding genes transcribed by RNA polymerase II enzyme in nucleus and led to production of a hairpin-formed molecule called “Pri-miRNA”. Pri-miRNA molecule turns into a precursor molecule called “Pre-miRNA” molecule by DROSHA and DGCR8 molecules’ action. Then, pre-miRNA enters cytoplasm through a nuclear export receptor called “Exportin 5.” In cytoplasm, this precursor is cut by Dicer-TRBP to produce a double-strand molecule known as “miRNA dublex.” After this process, one of these two strands remains as an active strand which can repress or even activate the target downstream genes in transcription or translation level. miRNA: microRNAs