Figure 4.
Regulation of let-7 biogenesis by LIN28A/B. LIN28A and LIN28B inhibit the biogenesis of let-7 via both TUTase-dependent and -independent pathways. LIN28A helps TUTases to oligo-uridylate pre-let-7. Methylated LIN28A binds to pri-let-7 in the nucleus and sequesters it into the nucleolus to prevent Drosha-mediated processing. LIN28B blocks the biogenesis of the let-7 miRNA via TUTase-independent pathways. The detailed relationship between LIN28B and TUTases needs to be further understood