Figure 1.

MiR biology. (A) MiR production. MiRs occur inter- and intragenically and can be transcribed by RNA Polymerase II or III (Pol-II or Pol-III).²³ Prior to nuclear export, the “pri-miR” hairpin is excised from the initial transcript by Drosha. Following nuclear export, the hairpin is processed by Dicer to produce the ∼20 nt mature miR. Image adapted from Bartel et al.⁵⁴ (B) MiR seeds and seed matches. Cartoon depicting a perfect seed match between a mature miR (top) and a target mRNA (bottom). The miR nucleotides commonly referred to as a “seed” (basepairs 2 through 8) and a perfect seed match in the mRNA are shown in red. Vertical lines indicate basepairing.