title: Protocadherin-1 Localization and Cell-Adhesion Function in Airway Epithelial Cells in Asthma.
abstract: BACKGROUND
  The asthma gene PCDH1 encodes Protocadherin-1, a putative adhesion molecule of unknown function expressed in the airway epithelium. Here, we characterize the localization, differential expression, homotypic adhesion specificity and function of PCDH1 in airway epithelial cells in asthma.
  
  
  METHODS
  We performed confocal fluorescence microscopy to determine subcellular localization of PCDH1 in 16HBE cells and primary bronchial epithelial cells (PBECs) grown at air-liquid interface. Next, to compare PCDH1 expression and localization in asthma and controls we performed qRT-PCR and fluorescence microscopy in PBECs and immunohistochemistry on airway wall biopsies. We examined homotypic adhesion specificity of HEK293T clones overexpressing fluorescently tagged-PCDH1 isoforms. Finally, to evaluate the role for PCDH1 in epithelial barrier formation and repair, we performed siRNA knockdown-studies and measured epithelial resistance.
  
  
  RESULTS
  PCDH1 localized to the cell membrane at cell-cell contact sites, baso-lateral to adherens junctions, with increasing expression during epithelial differentiation. No differences in gene expression or localization of PCDH1 isoforms expressing the extracellular domain were observed in either PBECs or airway wall biopsies between asthma patients and controls. Overexpression of PCDH1 mediated homotypic interaction, whereas downregulation of PCDH1 reduced epithelial barrier formation, and impaired repair after wounding.
  
  
  CONCLUSIONS
  In conclusion, PCDH1 is localized to the cell membrane of bronchial epithelial cells baso-lateral to the adherens junction. Expression of PCDH1 is not reduced nor delocalized in asthma even though PCDH1 contributes to homotypic adhesion, epithelial barrier formation and repair.
authors.affiliation: Department of Pediatric Pulmonology and Pediatric Allergology, Beatrix Children's Hospital, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|Department of Pathology & Medical Biology, Experimental Pulmonology and Inflammation Research, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|Clinical & Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: Grissel
authors.initials: G
authors.lastname: Faura Tellez
authors.affiliation: Department of Pediatric Pulmonology and Pediatric Allergology, Beatrix Children's Hospital, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Brigitte W M
authors.initials: BW
authors.lastname: Willemse
authors.affiliation: Department of Pathology & Medical Biology, Experimental Pulmonology and Inflammation Research, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Uilke
authors.initials: U
authors.lastname: Brouwer
authors.affiliation: Department of Pathology & Medical Biology, Experimental Pulmonology and Inflammation Research, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Susan
authors.initials: S
authors.lastname: Nijboer-Brinksma
authors.affiliation: Department of Biomedical Molecular Biology, Ghent University & Inflammation Research Center, VIB, Ghent, Belgium.|Laboratory for Molecular Diagnostics - Hematology, Ghent University Hospital, Ghent, Belgium.
authors.forename: Karl
authors.initials: K
authors.lastname: Vandepoele
authors.affiliation: Department of Pathology & Medical Biology, Experimental Pulmonology and Inflammation Research, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|Department of Pulmonology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Jacobien A
authors.initials: JA
authors.lastname: Noordhoek
authors.affiliation: Department of Pathology & Medical Biology, Experimental Pulmonology and Inflammation Research, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Irene
authors.initials: I
authors.lastname: Heijink
authors.affiliation: Department of Pathology & Medical Biology, Experimental Pulmonology and Inflammation Research, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|Brooke Laboratory, Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine, University Hospital Southampton, University of Southampton, Southampton, United Kingdom.
authors.forename: Maaike
authors.initials: M
authors.lastname: de Vries
authors.affiliation: Brooke Laboratory, Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine, University Hospital Southampton, University of Southampton, Southampton, United Kingdom.
authors.forename: Natalie P
authors.initials: NP
authors.lastname: Smithers
authors.affiliation: GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|Department of Pulmonology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Dirkje S
authors.initials: DS
authors.lastname: Postma
authors.affiliation: GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|Department of Pathology & Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Wim
authors.initials: W
authors.lastname: Timens
authors.affiliation: Clinical & Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.|Human Genetics and Genomic Medicine, Human Development & Health, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: Laura
authors.initials: L
authors.lastname: Wiffen
authors.affiliation: Department of Biomedical Molecular Biology, Ghent University & Inflammation Research Center, VIB, Ghent, Belgium.
authors.forename: Frans
authors.initials: F
authors.lastname: van Roy
authors.affiliation: Clinical & Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.|Human Genetics and Genomic Medicine, Human Development & Health, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: John W
authors.initials: JW
authors.lastname: Holloway
authors.affiliation: Clinical & Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Lackie
authors.affiliation: Department of Pathology & Medical Biology, Experimental Pulmonology and Inflammation Research, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Martijn C
authors.initials: MC
authors.lastname: Nawijn
authors.affiliation: Department of Pediatric Pulmonology and Pediatric Allergology, Beatrix Children's Hospital, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.|GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Gerard H
authors.initials: GH
authors.lastname: Koppelman
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism; D000368:Aged; D001249:Asthma / Q000235:genetics / Q000378:metabolism*; D001980:Bronchi / Q000166:cytology* / Q000378:metabolism; D015820:Cadherins / Q000235:genetics* / Q000378:metabolism*; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D008875:Middle Aged; D000091363:Protocadherins; D055815:Young Adult
chemical_list: D015820:Cadherins; C081683:PCDH1 protein, human; D000091363:Protocadherins