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. 2015 Dec 14;4:e10567. doi: 10.7554/eLife.10567

Figure 5. Elevated Wnt/β-catenin signaling abolishes hair follicle stem cell specification and suppresses Sox9 expression in hair follicles.

(A) Diagram of the experiments using Nfatc1-CreER::Rosa-stop-tdTomato::Exon3-Ctnnb1fl/wt mice. (B) Nuclear β-catenin staining indicates successful activation of Wnt/β-catenin signaling in upper hair follicle. (C–E) Abolished bulge niche formation and hair follicle stem cell specification in exon3-Ctnnb1 Het HFs compared to WT HFs. Krt6 (C) is a marker for inner layer bulge cells serving as a niche that can maintain quiescence for outer layer HFSCs. Sox9 (D) and CD34 (E) are adult hair follicle stem cell markers. (F) Wnt/β-catenin signal responsive cells, represented by β-gal positive cells in TOPGAL mice, do not express Sox9 during normal development. (G) Activation of Wnt/β-catenin signaling suppresses Sox9 expression in vivo. The arrows point to protrusions resulting from elevated Wnt/β-catenin signaling in exon3-Ctnnb1 Het HFs. (H) Diagram of the experiments using K14-rtTA::teto-Cre::Ctnnb1fl/fl mice. β-catenin is conditionally deleted in epithelial cells by feeding mice with Doxycyclin from E17.5 to P11. Samples were taken at P1 and P11. (I–J) Loss of Wnt/β-catenin signaling leads to expanded Sox9 expression in HFs at both the hair germ stage (I) and in postnatal skin (J). Scale bars: 50 μm.

DOI: http://dx.doi.org/10.7554/eLife.10567.012

Figure 5.

Figure 5—figure supplement 1. Effects of both gain and loss of function studies targeting Wnt/β-catenin signaling in skin.

Figure 5—figure supplement 1.

(A) Hematoxylin and eosin (H&E) staining of exon3-Ctnnb1 Het and control tail skin sections from P15 to P55. Control hair follicles enter into the first anagen from P15 to P25. Exon3-Ctnnb1 Het follicles enter into anagen around P45. Afterwards they return to telogen at P55, and new bulge structures reform. Scale bar: 50 µm. (B) Tail skin hair coats of control and exon3-Ctnnb1 Het mice at different time points. Notice in Het mice the disappearance of the hair coat at P30 and its reappearance at P100. Scale bar: 1 mm. (C) De novo formation of a normal niche in exon3-Ctnnb1 Het mice at P100. Note the recovered expression of the stem cell markers CD34 and Sox9; scale bar: 50 µm. (D) Spontaneous disappearance of exon3-Ctnnb1 Het-expressing cells shown by genotyping of isolated cells at different time points. (E) Conditional ablation of epithelium β-catenin leads to hair follicle development defects. β-catenin can be detected in the control mice but not in the epithelia of knockout mice. Scale bar: 50 µm. (F) Hair coat differences between WT and β-catenin cKO mice at P11.
DOI: http://dx.doi.org/10.7554/eLife.10567.013