title: Tight junction proteins in keratinocytes: localization and contribution to barrier function.
abstract: Recent research suggests that tight junctions (TJs) are located in the stratum granulosum, where they contribute to the barrier function of the epidermis. In this study, we investigated the formation of functional TJs in cultured normal human epidermal keratinocytes. We observed the development of permeability barrier function through the process of Ca(2+)-induced differentiation. Immunofluorescence analyses at 96 h after Ca(2+)-induced differentiation revealed concentrated portions of occludin, a TJ-specific marker, arranged as continuous lines circumscribing individual flattened suprabasal cells in areas with high concentrations of claudin-1 and -4. Transient Ca(2+) depletion reversibly disrupted the continuous network of TJ proteins and the permeability barrier. We also found that the addition of ochratoxin A weakened the permeability barrier and the expression of claudin-4. Our findings suggest that TJ proteins contribute to the permeability barrier in epidermal keratinocytes.
authors.affiliation: Basic Research Laboratory, Kanebo Cosmetics Inc., Kanagawa, Japan.
authors.forename: Takuo
authors.initials: T
authors.lastname: Yuki
authors.forename: Akinori
authors.initials: A
authors.lastname: Haratake
authors.forename: Hisa
authors.initials: H
authors.lastname: Koishikawa
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Morita
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Miyachi
authors.forename: Shintaro
authors.initials: S
authors.lastname: Inoue
mesh_terms: D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000493:pharmacokinetics; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D062445:Claudin-1; D062506:Claudin-4; D000078404:Epidermal Cells; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism*; D008854:Microscopy, Electron; D062793:Occludin; D009793:Ochratoxins / Q000494:pharmacology; D019108:Tight Junctions / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: C568108:CLDN1 protein, human; C568157:CLDN4 protein, human; D002121:Calcium Channel Blockers; D062445:Claudin-1; D062506:Claudin-4; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D009793:Ochratoxins; C025589:ochratoxin A; D002118:Calcium