Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2021 Sep 27;9:716462. doi: 10.3389/fcell.2021.716462

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Copyright © 2021 Balandeh, Mohammadshafie, Mahmoudi, Hossein Pourhanifeh, Rajabi, Bahabadi, Mohammadi, Rahimian, Hamblin and Mirzaei.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

PMC Copyright notice

Biogenesis of microRNAs and related mechanisms. A pri-miRNA transcript is the first stage of canonical miRNA biogenesis, which is cleaved by a micro-processor complex (containing Drosha and DGCR8), to create the precursor-miRNA (pre-miRNA). Then, the Exportin5/RanGTP-dependent pathway transports the pre-miRNA to the cytoplasm and processes it to produce a mature miRNA duplex. In the next step, the 5p or 3p strand of the mature miRNA duplex is loaded into a member of the Argonaute (AGO) family of proteins to form a miRNA-induced silencing complex (miRISC). Next, the small hairpin RNA (shRNA) is cleaved in a non-canonical pathway, and Exportin5/RanGTP transports it to the cytoplasm and processes it through an AGO2-dependent, but Dicer-independent cleavage mechanism. 7-Methylguanine capped (m7G)-pre-miRNA and mirtrons depend on Dicer for completing their cytoplasmic maturation, however there are differences in their nucleocytoplasmic shuttling. Exportin5/RanGTP exports mirtrons whereas Exportin1/m7G exports pre-miRNAs. Each pathway results in a functional miRISC complex which can recognize its target mRNA to induce translational suppression via interference with the eIF4F complex. Then, the poly(A)-deadenylases PAN2/3 and CCR4-NOT are recruited by the GW182 family protein attached to Argonaute, and PAN2/3 starts deadenylation while this process is completed by the CCR4-NOT complex, and finally the m7G cap on the target mRNA is removed via the decapping complex. Finally, the decapped mRNA undergoes 5′-3′ degradation through exoribonuclease XRN1 (modified from the results reported in Hayder et al. (2018) study).