Previous studies have established that newborn neurons generated during adult hippocampal neurogenesis contribute mostly to the inner granule cell layer and to a less extent to the middle granule cell layer (Figure 4D) (Duan et al., 2007). At 14 dpi, GFP+ neurons expressing KIAA1212 exhibited moderate over-extended migration phenotype with some cells into the outer granule cell layer and the molecular layer (Figure 4E). GFP+ neurons expressing CA-AKT exhibited similar positioning defects to those expressing KIAA1212 (Figure 4E). On the other hand, GFP+ new neurons expressing DISC1-shRNA exhibited stronger migration phenotype with a significant percentage of cells into the outer granule cell layer and molecular layer (Figure 4E). These results suggest that the AKT pathway may be only part of the signaling pathway controlling the positioning of new neurons in the adult brain.
