title: Contribution of tight junction proteins to ion, macromolecule, and water barrier in keratinocytes.
abstract: Tight junctions (TJs) form a selective barrier for ions, water, and macromolecules in simple epithelia. In keratinocytes and epidermis, TJs were shown to be involved in individual barrier functions. The absence of the TJ protein claudin-1 (Cldn1) in mice results in a skin-barrier defect characterized by lethal water loss. However, detailed molecular analyses of the various TJ barriers in keratinocytes and the contribution of distinct TJ proteins are missing. Herein, we discriminate TJ-dependent paracellular resistance from transcellular resistance in cultured keratinocytes using the two-path impedance spectroscopy. We demonstrate that keratinocyte TJs form a barrier for Na(+), Cl(-), and Ca(2+), and contribute to barrier function for water and larger molecules of different size. In addition, knockdown of Cldn1, Cldn4, occludin, and zonula occludens-1 increased paracellular permeabilities for ions and larger molecules, demonstrating that all of these TJ proteins contribute to barrier formation. Remarkably, Cldn1 and Cldn4 are not critical for TJ barrier function for water in submerged keratinocyte cultures. However, Cldn1 influences stratum corneum (SC) proteins important for SC water barrier function, and is crucial for TJ barrier formation for allergen-sized macromolecules.
authors: Department of Dermatology and Venerology, University Hospital Hamburg-Eppendorf, Hamburg, Germany.
authors: Nina
authors: N
authors: Kirschner
authors: Rita
authors: R
authors: Rosenthal
authors: Mikio
authors: M
authors: Furuse
authors: Ingrid
authors: I
authors: Moll
authors: Michael
authors: M
authors: Fromm
authors: Johanna M
authors: JM
authors: Brandner
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability / Q000502:physiology*; D002478:Cells, Cultured; D062445:Claudin-1 / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D062506:Claudin-4 / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D007477:Ions / Q000378:metabolism*; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D046911:Macromolecular Substances / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D062793:Occludin / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D062725:Tight Junction Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D019108:Tight Junctions / Q000502:physiology*; D014867:Water / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein / Q000172:deficiency / Q000235:genetics / Q000502:physiology
chemical_list: D062445:Claudin-1; D062506:Claudin-4; D007477:Ions; D046911:Macromolecular Substances; D062793:Occludin; D062725:Tight Junction Proteins; D062826:Zonula Occludens-1 Protein; D014867:Water