Fig. 6.

FoxP1 expression in the control and knock-out mouse brain and with in vitro analysis after 7 days in culture.

FoxP1 immunohistochemical analysis of E14 fetal mouse brain demonstrates FoxP1 expression in the WGE of wild-type (WT) controls (A) and lack of staining in the knock-out mutant (FoxP1^−/−) (B); lower panels show areas of higher magnification (A–B). RT-PCR of E14 fetal WGE confirms lack of FoxP1 in homozygous embryos (FoxP1^−/−) and intermediate levels in the heterozygous embryos (FoxP1^+/−) (C). E14 mouse WGE cultures from each of the three genotypes were differentiated for 7 days. Following fixation cells were double labelled for Foxp1 (red) and β-III-tubulin (green), DARPP-32 (green) and CTIP2 (red). BrdU (red) was also added 24 h prior to fixing to assess proliferation (D). Cells were counted and are represented as a percentage of total Hoechst positive nuclei (E and F). FoxP1 expression was lost in the FoxP1^−/− cultures, with no accompanying loss of neuronal numbers. DARPP-32 expression and CTIP2 expression were significantly reduced in the FoxP1^−/− cultures, with intermediate levels for the FoxP^+/− cultures. There was no significant difference in BrdU expression. Scale bars (D) = 50μm. Each bar on the graphs represents a mean of at least 3 cultures from different embryos and error bars are SEM. Significant post-hoc differences are indicated with brackets (ANOVA with Tukey-Wills post-hoc test, ***p < 0.001, *p < 0.05).