Fig. 5. Nkx2.1 activates the expression of an Lhx6 promoter reporter. Shown are examples of coronal, telencephalic slices at E13.5+1DIV that were electroporated with the constructs indicated. (A-C) Constitutively expressing pCAG-DsRed2 (A, pDsRed2) was introduced into a wt mouse embryo slice together with a reporter construct that contains 2.1 kb of the Lhx6 promoter region placed 5' to IRES-GFP (p5'-Lhx6-GFP, B). The merged image in C shows that the reporter construct is detectable in the ventral, Nkx2.1-expressing region (arrowheads) and not in the electroporated region of the medial cortex (arrow). (D-F) In marked contrast to B and C, electroporation of p5'-Lhx6-GFP into the MGE-like region (MGE^*) of this slice from an Nkx2.1 null results in no reporter expression (E,F). (G-I) However, the expression of p5'-Lhx6-GFP is rescued in an Nkx2.1-null slice by the addition of exogenous Nkx2.1 (red signal in G and I is NKX2.1 immunofluorescence). (J-L) A wild-type slice electroporated with a mutated reporter construct in which only the NKX2.1 consensus binding sequence has been deleted (p5'--Lhx6-GFP; see Materials and methods). Minimal expression of GFP is detected in the MGE with this construct (K-L). n=at least five experiments for each result. MGE, medial ganglionic eminence; LGE, lateral ganglionic eminence; Ctx, cerebral cortex. Scale bar: 200 µm in A for A-L.