Types of neurons that express mRNA of c-kit and its ligand in developing murine cerebellum

Murine cerebellum expresses mRNAs of c-kit and its ligand (Sl factor, SLF). Cell types expressing either SLF or c-kit were investigated using in situ hybridization. Purkinje cells were identified using anti-P₄₀₀/Inositol 1,4,5-triphosphate receptor monoclonal antibody (MoAb). Since all Purkinje, Golgi, basket and stellate cells express mRNA of glutamic acid decarboxylase (GAD), c-kit-expressing cells were identified by comparing their location to that of GAD-expressing cells. SLF mRNA was expressed by Purkinje cells throughout the observation period (day 2 to day 21 after birth). Three types of c-kit-expressing cells developed sequentially in different parts of the cerebellum; Golgi cells on day 2 after birth in the internal granular layer, basket cells on day 6 in the lower half of the molecular layer, and stellate cells on day 14 in the upper half of the molecular layer. The localization of the c-kit protein was also investigated using ACK2 MoAb that recognizes the extracellular domain of the c-kit protein. Basket-like synapses between Purkinje and basket cells, called “pinceau”, were strongly stained with ACK2 MoAb on day 21 after birth. Moreover, the whole molecular layer was stained faintly with the ACK2 MoAb. Since Purkinje cells form synapses between Golgi, basket and stellate cells, SLF and c-kit proteins appeared to play some roles for the synaptogenesis.