TRPA1 is required for dry-skin-evoked expressional changes in the skin. A, Gene expression was measured in cheek skin biopsies isolated from VEH- or AEW-treated TRPA1^+/+ mice that were free to scratch (WT SCR), and TRPA1^−/− mice. Gene expression was also measured in caudal back skin biopsies in which scratching was prevented (WT NSCR). The AEW gene expression data are normalized to VEH for each genotype and treatment area. Green indicates the AEW-evoked increase in expression; magenta, the AEW-evoked decrease in expression. All genes significantly altered in WT mice are shown (p < 0.05). B, Changes in gene expression with AEW treatment for FLG, IL31RA, AQP3, and IL33 in WT (black) and A1^−/− (white) mice as measured by quantitative PCR. Expression is reported as ΔΔCt. C, Micrographs of WT and A1^−/− skin are stained with KRT6 (brown). In VEH-treated skin, KRT6 is localized to hair follicles (arrows), whereas AEW-treated skin shows induction of KRT6 in the interfollicular epidermis (brackets). Nuclei are stained in blue. Scale bar, 50 μm.