Knockouts of both Vitamin D receptor (VDR) and its coactivator Med1 enhance epidermal permeability barrier function

Vitamin D receptor (VDR) is crucial for formation of epidermal permeability barrier and ceramide production, while mediator complex subunit 1 (Med1), a coactivator of VDR, mediates the action of VDR. VDR deficiency compromises epidermal permeability barrier in mice. Hence, we are investigating the dual role of VDR and Med1 in epidermal permeability barrier. Mice with VDR and Med1 specifically deleted in Keratin 14 expressing keratinocytes (DKO) by Cre-lox strategy are utilized. The mice with both floxed VDR and Med1 but no Cre serve as control. The data showed here that knockouts of both VDR and Med1 enhanced epidermal permeability barrier in mice, accompanied by increased expression levels of mRNA for keratinocyte differentiation marker-related proteins, fatty acid and ceramide productions, which all are required for formation of epidermal permeability barrier. Moreover, expression levels of mRNA for ceramide transporter (ABCA12) were also elevated in DKO mice vs. knockout of either VDR or Med1 alone. Collectively, these results demonstrate that knockouts of both VDR and Med1 enhance epidermal permeability barrier function via upregulating expression levels of mRNA for epidermal differentiation marker-related proteins and lipid synthetic enzymes, suggesting additional signaling pathway(s) involve regulatory role of VDR/Med1 in epidermal function. Epidermal mRNA profiles of P36 and 6-month-old VDR and Med1 double knockout and control mice