Next, we determined at a cellular resolution when cMaf expression begins in developing cortical interneurons (Figures 7M-M”’). Given that cMaf expression in the dorsal MGE and migrating cortical interneurons is dependent on Zfhx1b expression, and that repression of Nkx2-1 in these regions is also Zfhx1b dependent, we analyzed whether or not cMaf and Nkx2-1 are co-expressed in these cells. To this end, we performed a triple-labeling analysis: fluorescent in situ hybridization to detect cMaf in combination with immunofluorescence to label NKX2-1 and the EGFP+ Nkx2.1-Cre lineage (EGFP expression from CAG-CAT-EGFP, the Cre reporter allele). We found that cMaf RNA was expressed in EGFP+ cells derived from the MGE lineage that were migrating through the LGE corridor (LGE-Co) on route to the cortex (Figures 7M’, M” and M’”). These cells were NKX2-1-. On the other hand, NKX2-1 was expressed in cMaf- cells of the globus pallidus (Figures 7 M, M” and M”’). Thus, as NKX2-1 expression is repressed in immature cortical interneurons, cMaf expression begins.
