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Tight junctions (TJ) are essential components of polarized epithelia, and E-cadherin is important for their formation and maintenance. The bronchial epithelial cell line, 16HBE14o-expresses E- and P-cadherin, but not N-cadherin. E- and P-cadherin levels changed during culture, the former increasing after confluence, and the latter were markedly reduced. All detectable E-cadherin was bound to beta- and gamma-catenins. We investigated involvement of E-cadherin with epithelial integrity using an E-cadherin specific, function-blocking antibody, SHE78-7. Surprisingly, apical SHE78-7 exposure caused a prompt fall in transepithelial resistance (TER), while TER remained unchanged for 8 hrs after basal exposure then dropped. SHE78-7 exposure increased epithelial permeability to mannitol, inulin, and 9.5 kDa and 77 kDa dextrans and caused fragmentation and loss of the tight junction protein, ZO-1, from the cell borders in some areas. Ultrastructural studies showed that all junctional intercellular contact was lost in the center of SHE78-7 induced lesions. Near the lesion periphery, epithelial structure was maintained, but TJs were dysfunctional as shown by ruthenium red penetration. Analysis of epithelial penetration by SHE78-7 revealed discrete, local defects in the apical barrier at the top of some cell hills that permitted rapid access of the antibody to E-cadherin near the apical surface. In contrast, after basal exposure, antibody initially engaged with E-cadherin nearer the basal surface and only accessed apical E-cadherin later. Taken together with the TER measurements, these data suggest compartmentalization of E-cadherin function within 16HBE14o-cells, with only the apical E-cadherin adjacent to the tight junctions contributing to the function of the latter.

Type

Journal article

Journal

Cell Commun Adhes

Publication Date

01/2002

Volume

9

Pages

29 - 44

Keywords

Animals, Blotting, Western, Bronchi, Cadherins, Cell Line, Cytoskeletal Proteins, Dextrans, Dose-Response Relationship, Drug, Epithelial Cells, Epithelium, Humans, Immunoglobulin G, Immunohistochemistry, Inulin, Mannitol, Membrane Proteins, Mice, Occludin, Phosphoproteins, Protein Binding, Rats, Ruthenium Red, Tight Junctions, Time Factors, Zonula Occludens-1 Protein