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The structural analysis of adhesions mediated by Ep-CAM
M Balzar1, F A Prins, H A Bakker
1Department of Pathology, Leiden University Medical Centre, Leiden, The Netherlands. MBalzar@Path_1.MedFac.LeidenUniv.NL
Experimental Cell Research
|January 12, 1999
Summary
Epithelial cell adhesion molecule Ep-CAM mediates cell adhesion independently of calcium. In epithelial cells, Ep-CAM localizes to lateral membranes and associates with cadherins, but not tight junctions or desmosomes.
Area of Science:
- Cell biology
- Molecular biology
- Biochemistry
Background:
- The epithelial cell adhesion molecule Ep-CAM mediates calcium-independent homotypic cell-cell adhesion.
- Its precise structural organization and relationship with other adhesion molecules remain incompletely understood.
Purpose of the Study:
- To investigate the structural organization of Ep-CAM-mediated adhesions.
- To determine the relationship between Ep-CAM and other intercellular adhesion types.
Main Methods:
- Confocal immunofluorescence microscopy
- Immuno-electron microscopy
- Analysis of Ep-CAM-transfected cell lines, epithelial cells, and tissues
Main Results:
- Ep-CAM induced cell-cell proximity (10-14 nm) in transfected L cells, but did not form junctional complexes.
- In L cells co-transfected with E-cadherin, Ep-CAM and E-cadherin formed independent adhesion sites.
- In epithelial cells, Ep-CAM localized to lateral membranes, including adherens junctions, but excluded from tight junctions, desmosomes, and apical membranes.
- Ep-CAM colocalized with E-cadherin in epithelial cells, forming independent clusters.
Conclusions:
- Ep-CAM does not form junctional complexes in L cells.
- In epithelial cells, Ep-CAM is present at the lateral cell membrane, excluding tight junctions and desmosomes.
- Ep-CAM colocalizes with cadherins in epithelial cells, potentially modulating cadherin-mediated adhesions.