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Page 4 of 13 Zhang et al. Cancer Drug Resist 2024;7:30 https://dx.doi.org/10.20517/cdr.2024.62
Figure 1. Biogenesis and functional mechanism of miRNA. MiRNA is transcribed from DNA into primary miRNA (pri-miRNA)
transcripts by RNA polymerase II or III in the cell nucleus. Subsequently, pri-miRNA is cleaved into precursor miRNA (pre-miRNA).
Under the regulation of RanGTP protein, pre-miRNA is transported to the cytoplasm through the shuttle protein exportin 5. After
entering the cytoplasm, Dicer RNase catalyzes the cleavage of pre-miRNA into mature double-stranded miRNA. One of the miRNA
single strands binds to RISC (also known as miRISC). RISC: RNA-induced silencing complex.
Figure 2. Biogenesis and functional mechanism of circRNA. First, circRNA is transcribed from genomic DNA by RNA polymerase II or III.
Subsequently, during the splicing process, the downstream 5’ splice site of the precursor mRNA (pre-mRNA) is back-spliced with the
upstream 3’ splice site to form a circular molecule.
