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. Author manuscript; available in PMC: 2024 Mar 1.
Published in final edited form as: Neurosci Biobehav Rev. 2023 Jan 10;146:105040. doi: 10.1016/j.neubiorev.2023.105040

Figure 1: Programmed biogenesis of miRNAs.

Figure 1:

A stepwise description of mature miRNA biogenesis has been presented with a schematic diagram. The diagram shows the involvement of various ancillary protein factors and processing enzymes to support the transcription of primary miRNA transcripts and their subsequent processing through precursor miRNA to mature form. MicroRNA biogenesis following the canonical pathway begins in the nucleus. Successful transcription of primary miRNA (pri-miR) depends on the RNA polymerase II machinery in the nuclear environment. Following a canonical path, the pri-miRNA is processed by the nuclear RNase III enzyme Drosha to produce precursor miRNA (pre-miRNA). Pre-miRNA is transported to cytosolic environment with the help of Ran-GTP and Exportin5 transporter complex. In cytosol the pre-miRNA is processed by the RNase III enzyme Dicer to generate mature miRNAs. Mature miRNAs are incorporated into the RNA-induced silencing (RISC) complex, which regulates gene expression by pairing primarily to the 3′ untranslated region of protein-coding mRNAs to repress target mRNA expression. The arrest in target expression can be caused by any one of the three mechanisms: i) translational blockage by inhibiting the access of elongation factor/ribosome complex; ii) transcript degradation by decapping and exonuclease activity, and iii) transcript degradation by deadenylation. The figure was prepared using software from Biorender.com.