title: A mechanism enhancing macromolecule transport through paracellular spaces induced by Poly-L-Arginine: Poly-L-Arginine induces the internalization of tight junction proteins via clathrin-mediated endocytosis.
abstract: OBJECTIVE
  Poly-L-arginine (PLA) enhances the paracellular permeability of the Caco-2 cell monolayer to hydrophilic macromolecules by disappearance of tight junction (TJ) proteins from cell-cell junctions. However, the mechanism of the disappearance of TJ proteins in response to PLA has been unclear. In this study, we investigated the mechanism of disappearance of TJ proteins from cell-cell junctions after the application of PLA to Caco-2 cell monolayers.
  
  
  METHODS
  The membrane conductance (Gt), FITC-dextran (FD-4) permeability, and localization of TJ proteins were examined after the treatment of Caco-2 cell monolayers with PLA in the presence of various endocytosis inhibitors. In addition, the localization of endosome marker proteins was also observed.
  
  
  RESULTS
  Clathrin-mediated endocytosis inhibitors suppressed the increase in Gt and Papp of FD-4 induced by PLA, and also significantly suppressed the disappearance of TJ proteins induced by PLA. Furthermore, occludin, one of the TJ proteins, colocalized with early endosome and recycling endosomes after the internalization of occludin induced by PLA, and then was recycled to the cell-cell junctions.
  
  
  CONCLUSIONS
  PLA induced the transient internalization of TJ proteins in cell-cell junctions via clathrin-mediated endocytosis, subsequently increasing the permeability of the Caco-2 cell monolayer to FD-4 via a paracellular route.
authors.affiliation: Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Yamaki
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ohtake
authors.forename: Masaki
authors.initials: M
authors.lastname: Uchida
authors.forename: Toshinobu
authors.initials: T
authors.lastname: Seki
authors.forename: Hideo
authors.initials: H
authors.lastname: Ueda
authors.forename: Jun
authors.initials: J
authors.lastname: Kobayashi
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Morimoto
authors.forename: Hideshi
authors.initials: H
authors.lastname: Natsume
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D018938:Caco-2 Cells / Q000187:drug effects* / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects*; D006801:Humans; D010455:Peptides / Q000494:pharmacology*; D010539:Permeability / Q000187:drug effects; D062725:Tight Junction Proteins / Q000378:metabolism*
chemical_list: D002966:Clathrin; D010455:Peptides; D062725:Tight Junction Proteins; C015462:polyarginine