MRNA regulation mediated by microRNAs (miRNAs)

Copyright information:Taken from "MicroRNAs in Gene Regulation: When the Smallest Governs It All"Journal of Biomedicine and Biotechnology 2006;2006():-.Published online 3 Jul 2006PMCID:PMC1559927. miRNA genes are transcribed by RNA polymerase II into primary miRNAs (pri-miRNAs), which are processed by Drosha, acting in concert with DiGeorge syndrome critical region 8 (DGCR8) protein within the microprocessor complex, into ∼60 to 70 nt miRNA precursors (pre-miRNAs). Following export via exportin-5, pre-miRNAs are cleaved by Dicer, acting in concert with transactivating response RNA-binding protein (TRBP) within the pre-miRNA processing complex, to generate an imperfect miRNA:miRNA* duplex of ∼ 21 to 23 nt. After a strand selection/separation process, the mature miRNA is loaded into an effector miRNA-containing ribonucleoprotein (miRNP) complex that will recognize and mediate repression or cleavage of specific mRNAs. Synthetic small interfering RNAs (siRNAs) can be introduced into cells and be incorporated into the endogenous miRNA-guided RNA silencing machinery to mediate cleavage of the targeted mRNA.