Next, we analyzed the phenotype using molecular markers of MGE-derived cells including Nkx2-1 and Lhx6. While Nkx2-1 RNA and protein is expressed throughout the VZ and SVZ of the MGE, its expression thereafter is restricted to specific neuronal lineages. MGE-derived cortical interneurons repress Nkx2-1 expression as they migrate out of the MGE while most, but not all, classes of striatal interneurons maintain Nkx2.1 expression. (Flandin et al., 2010; Marin et al., 2000; Nóbrega-Pereira et al., 2008; Sussel et al., 1999). In the mutants, there was a subtle increase in Nkx2-1 RNA expression in the LGE and CGE (Figures 1H-1J’). This increase was more apparent at higher magnification when analyzing NKX2-1 protein expression (Figures 1G and 1G’), and at later stages (E13.5 and E15.5) (Figures 1 N-P’ and 2A-F’).
