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Epithelial polarity defects lead to altered distribution of Matriptase-1 within the basolateral domain of peridermal cells and of Par2b in basal cells. (A-D) atp1b1a mutants and lgl2 morphants display a shift of eGFP-St14a from lateral towards basal sides of peridermal cell membranes. (A-C’) Live confocal z-stack images of eGFP-St14a in peridermal cells of 48 hpf, krt4:egfp-st14a-injected wild-type (A), atp1b1a-/- (B), and lgl2 MO (C) embryos, presented as sum slices projections (A-C) and orthogonal views (A’-C’); scale bar: 10 μm. (A”-C”) Grey values obtained from the plot profile of yellow lines crossing cells in A-C. (D) Quantification of the ratio of the mean intensity of basally versus laterally localized eGPF (n = 15–30; significances were determined via a one-way ANOVA and Tukey’s post hoc test; ns, not significantly different (p>0.05); *,**, significantly different with p<0.05, p<0.01, respectively). (E-H). Basal cells of atp1b1a mutants display st14a-dependent localization of Par2b-eGFP in intracellular vesicles. Maximal intensity projections of live confocal z-stacks of basal cells in the fin fold region in wild-type siblings (E), atp1b1a mutants (F), and atp1b1a mutants injected with st14a MO (G), all transgenic for Tg(ΔNp63:par2b-egfp)fr59Tg; scale bar: 20 μm. All embryos display Par2b-GFP at the lateral membranes of basal keratinocytes. The wild-type sibling and st14a-deficient atp1b1a mutant display a rather homogeneous faint staining in the “interior” of cells (E,G), which might represent Par2b-GFP at the apical cell membranes, and which is even weaker in the atp1b1a mutant (F). On the other hand, some, but not all, basal keratinocytes of the atp1b1a mutant contain larger and roundish intracellular Par2b-GFP-positive structures (F), which might represent vesicles and which are absent from the wild-type and st14a-deficient atp1b1a mutant embryo (E,G). (H), Quantification of basal cells containing GFP-positive vesicle-like figures per embryo (n = 6–15 embryos; significances were determined via a one-way ANOVA and Tukey’s post hoc test; ns, not significantly different (p>0.05); *, significantly different (p<0.05)).
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