From: Emerging Roles for MicroRNAs in Perioperative Medicine Anesthes. 2016;124(2):489-506. doi:10.1097/ALN.0000000000000969 Figure Legend: MicroRNA (miRNA) biogenesis. miRNA biogenesis starts in the nucleus where RNA polymerase II (Pol II) generates large transcripts called primary miRNAs (pri-miRNA). Next, associated with DiGeorge Syndrome Critical Region 8 protein (DGCR 8), RNase nuclease Drosha synthesizes shorter hairpin-structured precursor miRNAs (pre-miRNA). The pre-miRNA is exported from the nucleus into the cytosol where RNase nuclease Dicer further shortens the hairpin-structured miRNA, resulting in double-stranded short duplex miRNAs. The mature strand gets incorporated into RNA-induced silencing complex (RISC) and guides this multiprotein complex to the target mRNA for gene repression. Binding of the miRNA to complementary sequences in the 3 prime untranslated region (3′UTR) of the mRNA of a target gene typically results in translational repression or mRNA degradation, thereby causing functional repression of the target gene. Date of download: 10/20/2017 Copyright © 2017 American Society of Anesthesiologists. All rights reserved.