Fig. 1

The biogenesis of miRNAs and their pathways to the target cell. a-d miRNA biogenesis starts in the nucleus. Pri-miRNA transcripts become pre-miRNA through the Drosha. Pre-miRNA is carried out of the nucleus through Exportin-5 into the cytoplasm. e-j MiRNA maturation is the elective loading of the functional strand of the small RNA duplex onto the RISC. miRISC induces the destruction of mRNA and translational inhibition via the interplay with the supplementary sequences in the 3′-UTR of target mRNA. k) MiRNAs are released in the extracellular environment or circulate through AGO2 protein, microvesicles, EXOs, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) particles