Role of bulge epidermal stem cells and TSLP signaling
in psoriasis (2019)
Figure 2

Figure 2: Mutant and non-mutant interfollicular keratinocytes have different proliferation and apoptotic rates during psoriasis-like disease progression

A. Schematic representation of the JunB and c-Jun double knockout mouse model (DKO*) with lineage tracing used to investigate the psoriasis-like disease development in mice. Briefly, DKO* psoriasis-like mouse model was generated by the cross of mice carrying the floxed JunB allele (JunBf/f) and floxed c-Jun allele (c-Junf/f) with the transgenic mice expressing the Cre recombinase-estrogen receptor fusion under the control of the basal keratinocyte specific K5 promoter (K5-Cre-ERT) to obtain JunBf/f c-Junf/f K5-Cre-ERT mice. To trace epidermal specific deletion of JunBf/f and c-Junf/f in DKO* mice, global double-fluorescent Cre reporter mouse Gt(ROSA)26Sortm4(ACTB-tdTomato,-EGFP)Luo/J (referred as mT/mG) was crossed with DKO* mice (referred as DKO*-mT/mG).

B. Experimental timeline to induce psoriasis-like disease in 8 week-old mice with four consecutive doses of tamoxifen injections (2 mg). Upon induction, non-mutant keratinocytes express Tomato, while mutant keratinocytes express GFP. GFP expression was analyzed at 0, 5, 7, 15 and 30 days post-induction.

C. Composite immunofluorescent images showing GFP expression of whole-ear sections from DKO*-mT/mG mice at day 5, 7, 15 and 30. Increased GFP expression is shown at day 7 followed by progressive decrease of GFP+ keratinocytes (white dotted line represents basal layer, and red dotted line represents outermost skin layer). n=3 per time point.

D. Quantification analysis of GFP expression (top) and epidermal thickness (bottom) of DKO* mice at different time points during psoriasis-like disease progression. n=6 per time point. Statistical significance *p<0.05, **p<0.01, ***p<0.001 (t-student two tailed-test relative to control group). See Supplemental Appendix Table 2 for exact p-Value.

E. Quantification analysis of cleaved Caspase-3 (cCas3 top) and Ki67 (bottom) in ear skin of DKO* mice at different time points during psoriasis-like disease progression. n=3 per time point. Statistical significance *p<0.05, **p<0.01, ***p<0.001 (t-student two tailed-test). See Supplemental Appendix Table 2 for exact p-Value.

F. Intravital confocal time-lapse imaging of non-mutant Tomato keratinocytes and mutant GFP keratinocytes of DKO*-mT/mG at day 7 after first tamoxifen injection. Dotted circles emphasize areas in which mutant GFP+ keratinocytes are replaced by non-mutant Tomato+ keratinocytes.

G. Percentage of GFP+ area eliminated during intravital confocal time-lapse imaging at day 5, 7 and 15 in DKO*-mT/mG mice (Time-lapse 1:8h). Positive value: Area of GFP increased. Negative value: Area of GFP reduced.

H. Fluorescence imaging of DKO*-mT/mG ear skin at day 30 after first tamoxifen injection shows that remaining mutant GFP+ keratinocytes reside along the hair follicles. White dotted line separates epidermis and dermis. White arrows represent GFP+ hair follicles.

I. Intravital confocal time-lapse imaging of DKO*-mT/mG at day 15 after first tamoxifen injection. Mutant GFP+ Keratinocytes (white arrows) are maintained around hair follicles.