Figure 1.

Biogenesis of miR-146a. Pri-miR-146a is formed by RNA polymerase II, which is further processed by capping, splicing, and polyadenylation. The long pre-miR-146a is cleaved by the microprocessor to release a hairpin-shaped pre-miR-146a. This leaves the nucleus through exportin 5 (XPO5) into the cytoplasm. In the cytoplasm, DICER with transactivation-responsive RNA-binding protein (TRBP) further acts on the pre-miR-146a to generate miRNA duplex. Argonaute protein selectively binds to one of the strands of miRNA, and a miRNA-induced silencing complex (miRISC) assembly is formed. The strand to which argonaute binds serves as a guide strand and leads the complex to complementary target mRNAs with GW182 protein family members for post-transcriptional gene silencing forming processing bodies (P-bodies). The other fate of miRNA is degradation if it is not needed.