title: Clathrin-mediated endocytosis regulates occludin, and not focal adhesion, distribution during epithelial wound healing.
abstract: BACKGROUND
  Vesicle trafficking has long been suggested to play mechanistic roles in regulating directed cell migration. Recent evidence demonstrates that specific cell types and modes of migration involve transport of particular cargo through particular pathways. Epithelial wound healing is essential in tissue repair. However, investigations into the mechanisms regulating cell migration have mainly focused upon other models such as fibroblast-derived cells. Roles for vesicle trafficking pathways in regulating directed cell migration have been identified in recent studies, but mechanisms through which endocytosis might be involved in epithelial wound healing have not been as well studied. Therefore, we analysed potential regulatory roles for endocytosis pathways during epithelial cell motility, with a particular focus on cell adhesion.
  
  
  RESULTS
  Specifically, and in contrast to studies in fibroblasts, we find no evidence for a link between endocytosis and the distribution of focal adhesions. However, the localisation of occludin, an essential component of tight junctions, is regulated through endocytosis. We identified epithelial monolayer wounding as a stimulus for endocytosis of occludin and have shown that internalisation of occludin from the wound edge occurs through clathrin-mediated endocytosis (CME) into a rab5-positive compartment.
  
  
  CONCLUSIONS
  Thus, these studies have evaluated mechanistic roles for dynamin-dependant, CME and caveolar endocytosis during epithelial wound healing and have provided contrasting observations between analyses of cell motility in fibroblast models and epithelial cells. In conclusion, these studies have identified a novel mechanism for regulation of occludin during wound healing.
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Fletcher
authors.forename: Natalie S
authors.initials: NS
authors.lastname: Poulter
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Haining
authors.forename: Joshua Z
authors.initials: JZ
authors.lastname: Rappoport
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D051242:Caveolin 1 / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002966:Clathrin / Q000378:metabolism*; D018699:Coated Vesicles / Q000378:metabolism*; D004285:Dogs; D034285:Dynamin II / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D022001:Focal Adhesions; D006835:Hydrazones / Q000494:pharmacology; D061985:Madin Darby Canine Kidney Cells; D008954:Models, Biological; D062793:Occludin / Q000378:metabolism*; D019108:Tight Junctions / Q000378:metabolism*; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology*; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D051242:Caveolin 1; D002966:Clathrin; D006835:Hydrazones; C511794:N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide; D062793:Occludin; D020696:rab5 GTP-Binding Proteins; D034285:Dynamin II