Department of Dermatology, Tenri Hospital, Mishima-cho 200, Tenri 632-8552, Japan, Department of Dermatology, Graduate School of Medicine, Kyoto University, Kyoto 755-8503, Japan, Division of Cell Biology, Department of Physiology and Cell Biology, Graduate School of Medicine, Kobe University, Kusunoki-cho 7-5-1, Chuo-ku, Kobe 650-0017, Japan
Tight junctions (TJs) are one type of intercellular junction. TJs prevent diffusion of solutes through the intercellular spaces in simple and stratified epithelia. Mice lacking claudin-1 (an adhesion molecule at TJs) show dehydration from the skin by impaired barrier function of epidermal TJs. Meanwhile, a human hereditary disease with ichthyosis (NISCH syndrome) has been found to be a claudin-1-deficient disease. The two models of lacking-claudin-1 indicate that TJs are related not only to the epidermal barrier but also to keratinization. Research of TJs in epidermis is reviewed in view of the barrier to keratinization.