Next, we tested whether the mutant cells that failed to migrate to the pallium had features of the globus pallidus or striatal interneurons. We examined expression of several globus pallidus markers including Kcnmb4, Kctd12, Gbx2 and Lhx8. Unlike the abnormal expression of Lhx6, Sst, Nkx2-1 and Sox6, expression of Kcnmb4, Kctd12, Gbx2 and Lhx8 appeared normal in the Zfhx1b mutants (Figures 2M-2O’, 2S-2U’, and S2J-S2O’), providing evidence that the abnormal collections of cells correspond either to abnormally migrated cortical interneurons, or to striatal interneurons, and not globus pallidus neurons. Furthermore, as Gbx2 and Lhx8 expression and function are linked to the development of striatal cholinergic interneurons (Chen et al., 2010; Zhao et al., 2003), these results provided evidence that increased striatal Nkx2-1 expression did not correspond to cells destined to become striatal cholinergic interneurons.
