Chunk #22 — Results — Deleting Zfhx1b in SVZ of the MGE Using DlxI12b-Cre Phenocopies Loss of Zfhx1b function in the VZ (Nkx2.1-Cre) — Postnatal Analysis of cortical and striatal interneuron phenotypes in Nkx2.1-Cre;Zfhx1b mutants
As NPY, Sst, and nNos are also expressed in subsets of cortical interneurons, their increased striatal expression does not provide unequivocal information about whether supernumerary cells correspond to cortical interneurons that failed to correctly migrate, or to interneurons that changed fate due to the mutation. To this end, we searched for a marker that is expressed in striatal, but not cortical interneurons. Substance P receptor (TacR1) is robustly expressed in striatal interneurons (Ardelt et al., 1996). We found that TacR1 is almost exclusively expressed in striatal and not cortical interneurons at E15.5, P0 and P15 (Figures 4L, 4L’, 4Q, 4Q’, S4D-S4F’, and data not shown). In Zfhx1b-Nkx2.1-Cre mutants at P0, there was increased striatal TacR1 expression (Figure 4Q-4Q’), supporting the idea that at least some of the mutant cells are adopting a striatal interneuron identity.
