ملف:MiRNA.svg

Overview of the miRNAs biogenesis. In the canonical pathway in the nucleus, pri-miRNAs are cleaved into pre-miRNAs by Drosha. Pre-miRNAs are exported to the cytoplasm by exportin 5. In the cytoplasm, pre-miRNAs are cleaved into small dsRNAs by Dicer. Then, RISC mediates the recognition of the mRNA to be targeted. In the non-canonical pathway (Mirtron), Drosha cleavage is substituted with splicing. pri-miRNAs (pre-mRNAs) are processed to pre-miRNAs by the spliceosome machinery and debranching enzyme to generate double-stranded loop structures like the regular miRNAs. Subsequently, the RNA product of splicing adopts a pre-miRNA like form, and transferred to the cytoplasm by exportin 5 to continue with the canonical pathway. For more details please refer to the text.