Volume 13, Issue 6, Pages 1090-1095 (November 2015) Apical versus Basal Neurogenesis Directs Cortical Interneuron Subclass Fate  Timothy J. Petros, Ronald S. Bultje, M. Elizabeth Ross, Gord Fishell, Stewart A. Anderson  Cell Reports  Volume 13, Issue 6, Pages 1090-1095 (November 2015) DOI: 10.1016/j.celrep.2015.09.079 Copyright © 2015 The Authors Terms and Conditions

Cell Reports 2015 13, 1090-1095DOI: (10.1016/j.celrep.2015.09.079) Copyright © 2015 The Authors Terms and Conditions

Figure 1 Genetic Strategy for Targeting MGE via In Utero Electroporation (A) Strategy to express Cre-dependent GFP into MGE progenitors via in utero electroporation (IUE) of Nkx2.1Cre embryos. (B) IUE of pCAG-LSL-IG + pCAG-mCherry results in GFP+ cells restricted to MGE progenitors (arrow) and MGE-derived cells migrating through the LGE. GFP+ cells are not observed in mCherry+ non-MGE cells (arrowheads). Scale bar, 50 μm. (C) At P21, embryos electroporated with pCAG-LSL-IG contain GFP+ cells in brain regions known to contain Nkx2.1-lineage cells. Str, striatum; Sep, septum; HC, hippocampus; Amyg, amygdala; Hyp, hypothalamus. Scale bar, 500 μm. (D) Putative GFP+ cortical SST+ Martinotti cell and PV+ basket cell. Scale bar, 50 μm. Cell Reports 2015 13, 1090-1095DOI: (10.1016/j.celrep.2015.09.079) Copyright © 2015 The Authors Terms and Conditions

Figure 2 pTα1-Expressing AP Progenitors Are Biased toward Generating SST+ Interneurons (A) Strategy to fate map pTα1+ AP progenitors via IUE into Nkx2.1Cre mice. (B) E12.5 IUE of pTα1-LSL-FlpO + pCAG-Frt-Stop-Frt(FSF)-GFP + pCAG-mCherry: GFP expression is restricted to the MGE and MGE-derived cells migrating into the cortex (arrows), whereas GFP is absent mCherry+ non-MGE-derived cells (arrowhead). Inset depicts higher-magnification view of GFP+/Cherry+ cells in the MGE SVZ/mantle region. Scale bars, 50 μm. (C) Representative images of P21 cortex from mice electroporated at E12.5 with pTα1-LSL-FlpO + pCAG-FSF-GFP or pNestin-LSL-FlpO + pCAG-FSF-GFP, with high-magnification images of individual cells depicting PV or SST expression. Scale bar, 50 and 10 μm. (D) pTα1+ MGE progenitors fate mapped at E12.5 display a strong bias to generate SST+ cortical interneurons at P21 compared to pNestin (pNes) fate-mapped cells. n = 4 brains for pTα1+ and 6 brains for pNes electroporations. Two-tailed t test, ∗∗∗p ≤ 0.001. Graphs depict average ± SEM. See also Figures S1–S3. Cell Reports 2015 13, 1090-1095DOI: (10.1016/j.celrep.2015.09.079) Copyright © 2015 The Authors Terms and Conditions

Figure 3 Driving MGE Progenitors toward APs or BPs Enhances the Production of SST+ and PV+ Interneurons, Respectively (A) Representative images of P21 cortex from Nkx2.1Cre mice that were electroporated at E12.5 with pCAG-LSL-DNMAML-IG, pCAG-LSL-IG, or pCAG-LSL-Insc-IG, with high-magnification images of individual cells depicting PV or SST expression. Scale bars, 50 and 10 μm. (B) DNMAML expression biases cortical interneurons toward a SST+ fate, whereas Insc biases cortical interneurons toward a PV+ fate. ANOVA: F(2,31) = 14.9, p < 0.001, with Tukey’s HSD post hoc test; ∗p ≤ 0.05, ∗∗∗p ≤ 0.001. n = 12 brains for control and 11 brains for DNMAML and Insc conditions. (C) Our data support a model in which Tα1+ APs preferentially give rise to SST+ interneurons whereas CCND2+ BPs preferentially give rise to PV+ interneurons. Graphs depict average ± SEM. See also Figures S2 and S3. Cell Reports 2015 13, 1090-1095DOI: (10.1016/j.celrep.2015.09.079) Copyright © 2015 The Authors Terms and Conditions