Figure 7.

The KE family FoxP2 mutation acts as a dominant-negative with regard to embryonic cortical neurogenesis. A, Fluorescence micrographs of E12 cortical precursor cultures cotransfected with a nuclear EGFP plasmid and expression constructs for mouse FoxP2 (mFoxP2; left), wild-type human FoxP2 (hFoxP2; left center), or human FoxP2 carrying the KE mutation (hFoxP2-R553H; right center and right), immunostained 1 d later for EGFP (green) and Flag (red). Cells were counterstained with Hoechst 33258 (blue). Dotted lines mark nuclear borders as indicated by Hoechst staining. Note the presence of cytoplasmic Flag-tagged hFoxP2-R553H. Scale bar, 20 μm. B, Quantification of the percentage of transfected cells in experiments as in A where Flag immunoreactivity was detectable in the cytoplasm. ***p < 0.001, ANOVA with Student–-Newman–Keuls post hoc analysis; n = 3 independent experiments. C–E, E13/14 murine cortices were electroporated with EGFP and pCMV-Tag4A empty vector (Control) or an expression construct for hFoxP2-R553H in the same vector. C, Fluorescence micrographs of coronal cortical sections 3 d postelectroporation, showing EGFP-positive cells (green). The white lines demarcate the different cortical regions. Scale bar, 100 μm. D, Quantification of sections similar to those in C for the number of EGFP-positive cells in the VZ/SVZ (left pair), IZ (middle pair), and CP (right pair). **p < 0.01; n = 7 animals for the control and 6 for hFoxP2-R553H. E, Quantification of sections similar to those in C for the percentage of EGFP-positive cells that were positive for Pax6 (left two bars), Tbr2 (middle two bars), or Satb2 (right two bars) 3 d after electroporation. *p < 0.05; ***p < 0.001; n = 6 for control and 5 for hFoxP2-R553H. Error bars indicate SEM.