Figure 5.

Establishment of the epidermal barrier is not compromised by Grhl3 overexpression. (A–C) Integrity of the permeability barrier was determined by dye penetration assay. At E16.5 (A), all genotypes show dye penetration, whereas at E18.5 (B) Grhl3^-/- is the only genotype with incomplete epidermal barrier. Note that barrier formation is rescued by transgenic expression of Grhl3 in Grhl3^{-/-;TgGrhl3/TgGrhl3} fetuses (in parallel with rescue of NTDs). Although Grhl3 overexpression causes SB, the epidermal barrier is established by E18.5 in hemizygous and homozygous transgenics. Note that limbs appear normal in transgenic fetuses, unlike in Grhl3^-/- (^*, abnormal forelimbs in B,C). Moreover, partially or completely open eyelids are visible in the transgenic fetuses (B). Scale bar represents 1 mm; CT: curly tail; ST: straight tail. (D) Analysis of gene expression in E18.5 skin samples in litters from compound mutant/transgenic or Grhl3^{ct/ct;TgGrhl3/0} intercrosses shows that Grhl3 overexpression is associated with increased expression of Lor, Tgm1 and Cdh1 (significant differences from Grhl3^ct/ct: ^*P < 0.05, ^**P < 0.001; ANOVA).