Figure 2.

Change in regional identity and neurotransmitter phenotype of early-born CP neurons in E15.5 Ngn mutants. E15.5 expression of cortical neuronal markers Id2 (A, B), Tbr1 (C, D), Robo1 (E, F), Slit1 (G, H) and Math2 (I–L), showing a correctly specified upper layer in Ngn2 and Ngn1;Ngn2 mutants above distinct gaps in lower CP expression (arrowheads, B, D, F, H, J, K) and in the medial cortex of Ngn2;Mash1 mutants (arrowheads, L). (M–P) The glutamatergic marker VGLUT2 was appropriately expressed in newly born neurons in the SVZ of wild-type (M) and Ngn2 mutants (N), whereas GluR2 was expressed in the IZ and CP of wild-type cortices (O), but displayed distinct gaps in the lower CP of Ngn2 mutants (arrowheads, P). (Q–T) Dlx1 transcripts and protein (insets) were detected in marginal zone and SVZ interneurons, and were ectopic in lower CP clusters in Ngn2 and Ngn1;Ngn2 mutants (arrowheads, R, S), and in medial clusters in Ngn2;Mash1 mutants (arrowheads, T). (U–W) Mash1 transcript and protein (insets) levels were moderately and strongly upregulated in Ngn2 (V) and Ngn2^KIM1 mutants (W), respectively. (X) Ectopic Dlx1+ clusters were in the deep CP in Ngn2^KIM1 mutants (asterisks). uc, upper CP; lc, lower CP; iz, intermediate zone; svz, subventricular zone.