Figure 3.

Notch2 regulates proliferation and differentiation of adult NSCs. (a) N2ICD mice were mated with GFAPCreER^T2/Rosa26-YFP (GCE/YFP) mice, which yields GCE/YFP/N2ICD mice that express both N2ICD and YFP upon tamoxifen-induced Stop codon excision in adult NSCs. YFP immunostaining in GCE/YFP/N2ICD mice was therefore used to identify cells that constitutively express N2ICD as a result of the GFAP-CreER^T2-mediated excision event. YFP+ cells in GCE/YFP mice were used as controls. YFP+ cells expressing a proliferation marker (Ki67) or differentiation markers (Sox2, GFAP, Dcx, NeuN) were used for quantification in (b) or (c), respectively. (b) Quantification of YFP/Ki67+ cells revealed a twofold increase in proliferating YFP+ cells in GCE/YFP/N2ICD mice compared with GCE/YFP mice in both the SGZ and SVZ, indicating increased proliferation in the neurogenic niche of adult mice with N2ICD expression. (c) Immunostaining for YFP and NSC markers (Sox2, GFAP; left panels) or neuronal markers (Dcx, NeuN; right panels) in the dentate gyrus in GCE/YFP/N2ICD and GCE/YFP mice. Quantification reveals that GCE/YFP/N2ICD mice have approximately a twofold increase in YFP+ cells expressing NSC markers compared with GCE/YFP mice, while the number of YFP+ neurons is strongly decreased (d). This indicates that N2ICD expression increases the number of NSCs, while preventing neurogenesis. GCL=granule cell layer. Bar diagrams show mean±S.E.M., *P<0.05, ***P<0.01 (Student's t-test). Scale bars are (c)=25 μm