title: A key claudin extracellular loop domain is critical for epithelial barrier integrity.
abstract: Intercellular tight junctions (TJs) regulate epithelial barrier properties. Claudins are major structural constituents of TJs and belong to a large family of tetra-spanning membrane proteins that have two predicted extracellular loops (ELs). Given that claudin-1 is widely expressed in epithelia, we further defined the role of its EL domains in determining TJ function. The effects of several claudin-1 EL mimetic peptides on epithelial barrier structure and function were examined. Incubation of model human intestinal epithelial cells with a 27-amino acid peptide corresponding to a portion of the first EL domain (Cldn-1(53-80)) reversibly interfered with epithelial barrier function by inducing the rearrangement of key TJ proteins: occludin, claudin-1, junctional adhesion molecule-A, and zonula occludens-1. Cldn-1(53-80) associated with both claudin-1 and occludin, suggesting both the direct interference with the ability of these proteins to assemble into functional TJs and their close interaction under physiological conditions. These effects were specific for Cldn-1(53-80), because peptides corresponding to other claudin-1 EL domains failed to influence TJ function. Furthermore, the oral administration of Cldn-1(53-80) to rats increased paracellular gastric permeability. Thus, the identification of a critical claudin-1 EL motif, Cldn-1(53-80), capable of regulating TJ structure and function, offers a useful adjunct to treatments that require drug delivery across an epithelial barrier.
authors: Department of Pathology & Laboratory Medicine, Emory University School of Medicine, Whitehead Biomedical Research Building, 615 Michael Street, Atlanta, GA 30322, USA.
authors: Randall J
authors: RJ
authors: Mrsny
authors: G Thomas
authors: GT
authors: Brown
authors: Kirsten
authors: K
authors: Gerner-Smidt
authors: Andre G
authors: AG
authors: Buret
authors: Jon B
authors: JB
authors: Meddings
authors: Clifford
authors: C
authors: Quan
authors: Michael
authors: M
authors: Koval
authors: Asma
authors: A
authors: Nusrat
mesh_terms: D000818:Animals; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D062445:Claudin-1; D062465:Claudin-3; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D008565:Membrane Proteins / Q000008:administration & dosage / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D062793:Occludin; D010455:Peptides / Q000008:administration & dosage / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D051381:Rats; D013329:Structure-Activity Relationship; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure
chemical_list: C568108:CLDN1 protein, human; C568122:CLDN3 protein, human; D062445:Claudin-1; D062465:Claudin-3; C568114:Cldn1 protein, rat; C568124:Cldn3 protein, rat; D003432:Cross-Linking Reagents; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; C568987:Ocln protein, rat; D010455:Peptides