Chao Chen, Zhifan Wang
Background: Skin barrier dysfunction is closely associated with impaired keratinocyte differentiation. Calcitriol helps maintain the stable state of the epidermis, but the role of caveolin-1 (Cav1)-associated calcium signaling in calcitriol-induced skin barrier-associated responses remains unclear.Methods: HaCaT human keratinocytes were treated with different concentrations of calcitriol, with or without methyl-β-cyclodextrin, to explore Cav1's role in D3-induced differentiation. Cell metabolic activity, apoptosis, intracellular Ca2+ levels, and migration were assessed using Cell Counting Kit-8 (CCK-8), Hoechst staining, Fluo-4AM staining, and scratch assays, respectively. The gene and protein levels of differentiation- and barrier-related markers, as well as calcium channel proteins (Cav1, p-Cav1, TRPV6 and Orai1), were analyzed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blotting.Results: Following calcitriol treatment, the differentiation of HaCaT cells was significantly promoted, the expression of differentiation- and barrier-related proteins was increased, and cell migration was significantly enhanced (p < 0.05). Calcitriol increased Cav1 expression and phosphorylation, accompanied by elevated intracellular Ca2+ levels and increased expression of the calcium-related proteins TRPV6 and Orai1 (p < 0.05). After disruption of Cav1-associated membrane signaling by methyl-β-cyclodextrin (MβCD), the calcitriol-induced increases in differentiation markers, barrier-associated proteins, and intracellular Ca2+ levels were significantly attenuated (p < 0.05), suggesting that Cav1-associated calcium signaling may be involved in calcitriol-induced keratinocyte differentiation and the expression of barrier-associated proteins.Conclusion: Calcitriol increased intracellular Ca2+ levels and was associated with increased expression of Cav1-related calcium signaling components, accompanied by enhanced keratinocyte differentiation and expression of barrier-associated proteins. Cav1-associated signaling may therefore participate in calcitriol-induced keratinocyte differentiation and epidermal barrier-associated responses. These findings provide mechanistic insight into calcitriol-mediated keratinocyte differentiation and highlight the potential involvement of Cav1-associated signaling in calcitriol-induced regulation of keratinocyte differentiation and barrier-associated protein expression.