Vitamin D3 analogue facilitates epithelial wound healing through promoting epithelial-mesenchymal transition via the Hippo pathway

Background Wound healing is a complex physiological process that is crucial for reestablishing the epithelial barrier following injury. Objective The aim of this study was to demonstrate the efficacy of calcipotriol, a synthetic vitamin D3 analogue, in wound healing in an acute mice wound model. Methods An excision wound model was established in mice, and the wound healing activity of calcipotriol was evaluated. Human keratinocyte cell lines, HaCaT and NHEK, were utilized in in vitro skin wound healing model. Cytokine expression levels were measured by real-time PCR and ELISA assay. The expression of epithelial-mesenchymal transition (EMT)-associated molecules and the phosphorylation of Yes-associated protein (YAP) was determined by western blotting. Results The increase in re-epithelialization by calcipotriol treatment early in the wound was associated with the EMT process. A scratch assay using HaCaT and NHEK cells also showed that calcipotriol administration resulted in effective wound closure. We demonstrated that calcipotriol promoted keratinocyte migration by interfering with the Hippo pathway. Calcipotriol-mediated enhancement of cell migration is related to downregulated phosphorylation of YAP and increased levels of YAP and PDZ-binding motif (TAZ). Mechanistically, we defined that calcipotriol facilitated the crosstalk between the YAP/TAZ and TGF-β/Smad signaling pathways, eliciting EMT in keratinocytes during the wound healing process. Conclusions These results suggest that the positive effect of calcipotriol on keratinocyte migration is mediated by the induction of EMT via the regulation of Hippo pathway, which promotes the acceleration of wound closure.