Figure 8: Schematic diagram for miR-153 regulated endocytotic and endosomal/lysosomal pathways.

During maturation-stage tooth development, EMPs in the enamel matrix are broke down into protein fragments with smaller sizes. The EMP debris is retrieved by clathrin-coated vesicles, which fuse with lysosomes within ameloblast for further processing and degradation. MiR-153 targets endocytosis and lysosomal digestion by regulating the expression of Cltc, Lamp1, Clcn4 and Slc4a4. In the whole process of ameloblast-mediated removal of EMPs, the acid-base balance extracellularly and within intracellular lumens needs to be tightly controlled by various ion transporters/exchangers located on the apical and basolateral membrane of maturation-stage ameloblast.