Figure 8

Altered expression of β-catenin target genes in mutant cerebral cortex. (A, B) X-gal staining (blue) for beta-galactosidase in the telencephalon of control (Emx1^Cre/+Apc^580S/+) and mutant (Emx1^Cre/+Apc^580S/580S) embryos at embryonic day (E)13.5 carrying the BAT-gal reporter transgene. X-gal staining in the cerebral cortex (cc) is less intense in the control (A) compared to the mutant (B). Brown immunostaining in (A, B) is for β-galactosidase. (C, D, F, G) In situ hybridisation for Axin2 (C, D) and Lef1 (F, G) transcripts (dark staining) in control (C, F) and mutant (D, G) forebrain at E13.5 presented as greyscale images. In controls, Axin2 expression is highest in the cortical hem (red arrow in (C)) and Lef1 expression is highest just adjacent to the hem (red arrow in (F)). In the mutant, expression of both Axin2 and Lef1 is high throughout the cerebral cortex. (E) qRT-PCR showing a large increase in the levels of Axin2 transcripts in the E13.5 cerebral cortex of mutant compared to control embryos. P-value calculated using Student's t-test is indicated above the bars. Error bars are standard error of the mean. The ubiquitous pale staining in (C-G) is non-specific background. (H-K) Immunostaining for c-myc and p21 (brown) in the telencephalon of control (H, J) and mutant embryos (I, K) at E13.5. The control cerebral cortex is negative for c-myc staining, but the mutant cerebral cortex has c-myc positive cells. P21 levels are also increased in the mutant. All sections are coronal and dorsal is up. Additional abbreviations: t, thalamus. Scale bars: (A, B) 400 μm; (C-G) 200 μm; (H-K) 100 μm.