Protocadherin-1 Localization and Cell-Adhesion Function in Airway Epithelial Cells in Asthma

PLoS One. 2016 Oct 4;11(10):e0163967. doi: 10.1371/journal.pone.0163967. eCollection 2016.

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.

MeSH terms

  • Adherens Junctions / metabolism
  • Aged
  • Asthma / genetics
  • Asthma / metabolism*
  • Bronchi / cytology*
  • Bronchi / metabolism
  • Cadherins / genetics*
  • Cadherins / metabolism*
  • Cell Adhesion
  • Cell Membrane / metabolism*
  • Epithelial Cells / cytology
  • Epithelial Cells / metabolism*
  • Female
  • Gene Expression Regulation
  • HEK293 Cells
  • Humans
  • Male
  • Middle Aged
  • Young Adult

Substances

  • Cadherins
  • PCDH1 protein, human

Grant support

This work was supported by Asthma UK Foundation Grant (11/010), University Medical Center Groningen and the University of Southampton, Mechanisms of the Development of Allergy (MeDALL), a collaborative project done within the EU under the Health Cooperation Work Programme of the seventh Framework programme (grant agreement number 261357). Netherlands Asthma Foundation Grant AF 3.2.09.