Fig. 1
From: MicroRNAs and obesity-induced endothelial dysfunction: key paradigms in molecular therapy
Summarized scheme of miRNAs biogenesis and mechanism of action: In the nucleus, Pol II and Pol III RNA polymerases transcribe the coding sequences of miRNAs. Drosha binds to DGCR8 cofactor to catalyze the formation of pre-miRNA. Pre-miRNA is then translocated by the exportins system from the nucleus to the cytoplasm, where it is then cleaved by the Dicer-TRBP complex to form a 22nt-dsRNA. Within the cytoplasm, the 22nt-dsRNA interacts with AGO proteins to form the RISC complex, while the passenger strand is degraded. The 22nt-RNA guide chain constitutes a mature miRNA that guides the RISC complex towards the 3-UTR regions of the mRNA targets. This interaction either represses their translation or induces their degradation. Pol: polymerase; Drosha: ribonuclease III double-stranded RNA-specific endoribonuclease; DGCR8: DiGeorge syndrome chromosomal region 8; Dicer: helicase with RNase motif; TRBP: TAR RNA binding protein; AGO: Argonaute protein; RISC: RNA-induced silencing complex; UTR: untranslated region