Typical pathway of miRNA formation

Typical pathway of miRNA formation. miRNA genes are transcribed in the nucleus primarily through the RNA polymerase complex (RNA Pol II) to form hairpin-structured long primary miRNA transcripts (pri-miRNAs). The 5′ pri-miRNA terminus has a guanosine cap, but the 3′ terminus is not always polyadenylated. dgCR8 and the Drosha protein microprocessing complexes direct the processing of pri-miRNAs, leading to the release of the 5′ and 3′ ends of the transcripts and subsequent conformational changes. The resulting precursor miRNAs (pre-miRNAs) are recognized through their 3′ free end and transported to the cytoplasm through the nuclear pore by the Exportin-5 and Ran-GTP complexes. In the cytoplasm, pre-miRNAs are bound by a complex of Dicer and TRBP proteins, and Dicer eliminates the transcript’s ring structure, forming a double complementary strand. The RISC degrades or inhibits miRNA formation; however, some miRNAs are still detected in the cells and bodily fluids of organisms, and their roles remain unclear

Publication

Natural Products Treat Colorectal Cancer by Regulating miRNA (2023) Shuoxi Guo, et al. Pharmaceuticals (Basel). 2023 Aug;16(8). Figure: F1. Homo sapiens

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