title: A role for tricellulin in the regulation of gill epithelium permeability.
abstract: The apical-most region of cell-to-cell contact in a vertebrate epithelium is the tight junction (TJ) complex. It is composed of bicellular TJs (bTJs) that bridge two adjacent epithelial cells and tricellular TJs (tTJs) that are points of contact between three adjoining epithelial cells. Tricellulin (TRIC) is a transmembrane TJ protein of vertebrates that is found in the tTJ complex. Full-length cDNA encoding rainbow trout TRIC was cloned and sequenced. In silico analysis of rainbow trout TRIC revealed a tetraspannin protein with several putative posttranslational modification sites. TRIC mRNA was broadly expressed in rainbow trout tissues and exhibited moderately greater abundance in the gill. In a primary cultured gill epithelium, TRIC localized to tTJs and TRIC protein abundance increased in association with corticosteroid-induced reductions in paracellular permeability. Sodium caprate was used to compromise cultured gill epithelium integrity by disrupting the tTJ complex. Sodium caprate treatment caused a reversible reduction in transepithelial resistance, caused an increase in paracellular permeability (as measured by [³H]PEG-4000 flux), and displaced TRIC from tTJs while leaving bTJs intact. Data from this study support the view that tTJs and the TJ protein TRIC 1) play a role in maintaining gill epithelium integrity and 2) contribute to the regulation of gill epithelium permeability.
authors.affiliation: Department of Biology, York University, Toronto, Ontario, Canada. dennisk@yorku.ca
authors.forename: Dennis
authors.initials: D
authors.lastname: Kolosov
authors.forename: Scott P
authors.initials: SP
authors.lastname: Kelly
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003652:Decanoic Acids / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D005880:Gills / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006854:Hydrocortisone / Q000494:pharmacology; D062794:MARVEL Domain Containing 2 Protein / Q000032:analysis / Q000502:physiology*; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000502:physiology*; D019108:Tight Junctions / Q000187:drug effects / Q000502:physiology
chemical_list: D003652:Decanoic Acids; D062794:MARVEL Domain Containing 2 Protein; C031071:decanoic acid; D006854:Hydrocortisone
keywords: cortisol; paracellular permeability; pavement cell; sodium caprate; tight junction