Potential role of TRPV5 in the formation of epidermal calcium gradients and the epidermal permeability barrier = Potential role of TRPV5 in the formation of epidermal calcium gradients and the epidermal permeability barrier

다국어 초록 (Multilingual Abstract)

TRPV5 and 6, which belong to the superfamily of transient receptor potential channels, constitute the apical Ca2+ entry mechanism in active Ca2+ transport in kidney and intestine. Considering the calcium gradient in viable epidermis, it is interesting that the extracellular calcium ion at the SG-SC junction is abruptly disappeared. Currently, it is unclear which receptors or ion channels are underlying the acute loss of calcium ions at SG-SC junction. In this study, we have investigated the potential role of TRPV5 and 6 in the regulation of epidermal calcium ion concentration. Firstly, epidermal expressions of TRPV5 and 6 were observed in the suprabasal layer of normal skin, whereas in the lesional skin of atopic dermatitis and psoriasis, epidermal expression of TRPV5 and 6 were lost. Treatments of psoriasis, however, resulted in the re-appearance of TRPV5 and 6 expressions in epidermis. In an animal model, acute disruption of epidermal permeability barrier induced the decrease of TRPV 5 and 6 expressions, and the recovery of those proteins was parallel to that of calcium gradient. The occlusion after barrier disruption, which inhibits the recovery of calcium gradient, also inhibited TRPV5 and 6 expressions. These results suggested that TRPV5 and 6 are closely related with the epidermal calcium gradient. Since the extracellular pH environment regulates the expressions of TRPV5 and 6, it can be suggested that TRPV5 and 6 are potential sensor for pH environment, which controls calcium movement and keratinocyte differentiation.