title: Claudin-binder C-CPE mutants enhance permeability of insulin across human nasal epithelial cells.
abstract: OBJECTIVE
  Intranasal insulin administration has therapeutic potential for Alzheimer's disease and in intranasal administration across the nasal mucosa, the paracellular pathway regulated by tight junctions is important. The C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) binds the tight junction protein claudin and disrupts the tight junctional barrier without a cytotoxic effect. The C-CPE mutant called C-CPE 194 binds only to claudin-4, whereas the C-CPE 194 mutant called C-CPE m19 binds not only to claudin-4 but also to claudin-1.
  
  
  METHODS
  In the present study, to investigate the effects of C-CPE mutants on the tight junctional functions of human nasal epithelial cells (HNECs) and on the permeability of human recombinant insulin across the cells, HNECs were treated with C-CPE 194 and C-CPE m19.
  
  
  RESULTS
  C-CPE 194 and C-CPE m19 disrupted the barrier and fence functions without changes in expression of claudin-1, -4, -7, and occludin or cytotoxicity, whereas they transiently increased the activity of ERK1/2 phosphorylation. The disruption of the barrier function caused by C-CPE 194 and C-CPE m19 was prevented by pretreatment with the MAPKK inhibitor U0126. Furthermore, C-CPE 194 and C-CPE m19 significantly enhanced the permeability of human recombinant insulin across HNECs and the permeability was also inhibited by U0126.
  
  
  CONCLUSIONS
  These findings suggest that C-CPE mutants 194 and m19 can regulate the permeability of insulin across HNECs via the MAPK pathway and may play a crucial role in therapy for the diseases such as Alzheimer's disease via the direct intranasal insulin administration.
authors.affiliation: a Department of Cell Science , Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine , Sapporo , Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kojima
authors.affiliation: b Laboratory of Bio-Functional Molecular Chemistry , Graduate School of Pharmaceutical Sciences, Osaka University , Suita , Japan.
authors.forename: Masuo
authors.initials: M
authors.lastname: Kondoh
authors.affiliation: c Department of Otolaryngology and.
authors.forename: Takashi
authors.initials: T
authors.lastname: Keira
authors.affiliation: c Department of Otolaryngology and.
authors.forename: Ken-Ichi
authors.initials: KI
authors.lastname: Takano
authors.affiliation: a Department of Cell Science , Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine , Sapporo , Japan.|c Department of Otolaryngology and.
authors.forename: Takuya
authors.initials: T
authors.lastname: Kakuki
authors.affiliation: a Department of Cell Science , Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine , Sapporo , Japan.|c Department of Otolaryngology and.
authors.forename: Yakuto
authors.initials: Y
authors.lastname: Kaneko
authors.affiliation: c Department of Otolaryngology and.
authors.forename: Ryo
authors.initials: R
authors.lastname: Miyata
authors.affiliation: c Department of Otolaryngology and.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Nomura
authors.affiliation: c Department of Otolaryngology and.
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Obata
authors.affiliation: a Department of Cell Science , Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine , Sapporo , Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kohno
authors.affiliation: a Department of Cell Science , Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine , Sapporo , Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Konno
authors.affiliation: d Department of Pathology , Sapporo Medical University School of Medicine , Sapporo , Japan.
authors.forename: Norimasa
authors.initials: N
authors.lastname: Sawada
authors.affiliation: c Department of Otolaryngology and.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Himi
mesh_terms: D002460:Cell Line; D057167:Claudins / Q000378:metabolism*; D004768:Enterotoxins / Q000737:chemistry*; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000008:administration & dosage* / Q000737:chemistry*; D009297:Nasal Mucosa / Q000378:metabolism*; D062793:Occludin / Q000737:chemistry / Q000378:metabolism; D010539:Permeability / Q000187:drug effects; D019108:Tight Junctions / Q000378:metabolism
chemical_list: D057167:Claudins; D004768:Enterotoxins; D007328:Insulin; D062793:Occludin; C035598:enterotoxin, Clostridium
keywords: C-CPE; MAPK; claudins; human nasal epithelial cells; insulin; tight junctions