Extended Data Figure 1. Generation of an inducible, humanized SRGAP2C transgenic mouse line.

(a-b) Design strategy for generating SRGAP2C conditional knock in mice. 3x HA tagged SRGAP2C was inserted into a Rosa26 targeting vector (a), which contains a CAG promoter, a floxed STOP-Neomycin cassette, and Rosa26 homology arms. Image not to scale. Using homologous recombination, the targeting vector was inserted between exon 1 and 2 of the Rosa26 locus (b). (c-d) Verification of SRGAP2C targeting in mouse embryonic stem cells using Southern blot analysis with probes that distinguish the targeted allele (12.2 kb in (c), 13.1 kb in (d)) from the wild-type allele (5.3 kb in (c), 9.2 kb in (d)). (e) Mice were genotyped by genomic PCR using the forward and reverse primers indicated that distinguish the WT Rosa26 allele or the SRGAP2C allele. (f) Western blot probed with anti-HA antibody of adult (P30) cortex isolated from SRGAP2C heterozygous conditional knock-in mice crossed with heterozygous Nex^Cre/+ mice (Cre+) or wild-type littermate (Cre-). The presence of Cre induces SRGAP2C-HA expression. Without Cre, no SRGAP2C was detected. Anti-Actin antibody was used as loading control. (g) Immunohistochemistry for HA on cortical brain sections from adult SRGAP2C heterozygous conditional knock-in mice crossed with heterozygous Nex^Cre/+ mice (Cre+) or wild-type littermate control (Cre-). Scale bar, 25 μm. (h) Same as g, on sections from SRGAP2C heterozygous conditional knock-in mice in which mRuby-Cre was sparsely expressed using in utero cortical electroporation. Scale bar, 10 μm.