Skip to main content
. Author manuscript; available in PMC: 2019 May 1.
Published in final edited form as: Adv Biol Regul. 2017 Aug 24;68:107–119. doi: 10.1016/j.jbior.2017.08.002

Figure 2. MicroRNA (miRNA, miR) and cancer.

Figure 2

miRs are short (~22 nucleotide) single-stranded RNA molecules. After transcription (1), the miR precursors undergo several processing steps in the nucleus and cytoplasm. In the nucleus a key step is their cleavage by endonucleases, such as Drosha (2) and the resulting pre-miR is exported from the nucleus (3). In the cytoplasm, Dicer (4) produces a mature miR duplex that, after unwinding (4), becomes associated with Ago2 in the RISC (RNA-induced silencing complex) (5). Once the miR is loaded onto the RISC, the entire complex targets mRNA based on sequence complementarity with the seed sequence (first 8 amino acids) of the miR. The association of miR-loaded RISC on mRNA functions to inhibit translation of the mRNA by either inhibiting ribosomal function or by inducing the degradation of the mRNA. This process is deregulated in several pathologies including cancer.