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Updated: May 13, 2026

Analysis of Protein-protein Interactions and Co-localization Between Components of Gap, Tight, and Adherens Junctions in Murine Mammary Glands
Published on: May 30, 2017
Epithelial cell adhesion molecule (EpCAM) regulates claudin dynamics and tight junctions
Chuan-Jin Wu1, Poonam Mannan, Michael Lu
1Dermatology Branch, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-1908, USA.
Epithelial cell adhesion molecule (EpCAM) regulates tight junction (TJ) function by controlling claudin protein levels. EpCAM knockdown enhances TJ formation and stability, suggesting a novel therapeutic target for epithelial barrier disorders.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Epithelial cell adhesion molecule (EpCAM) is a surface glycoprotein found on invasive carcinomas and epithelia.
- The role of EpCAM in regulating epithelial barrier function, particularly tight junctions (TJs), is not fully understood.
Purpose of the Study:
- To investigate the regulatory role of EpCAM in the composition and function of tight junctions (TJs).
- To elucidate the molecular mechanisms by which EpCAM influences TJ integrity and epithelial adhesion.
Main Methods:
- EpCAM knockdown in human colon carcinoma and intestinal epithelial cell lines (T84, Caco-2) using shRNAs.
- Analysis of TJ formation, trans-epithelial electroresistance, and resistance to calcium chelation.
- Immunoprecipitation and co-immunoprecipitation to identify protein interactions between EpCAM and claudins.
- Immunofluorescence microscopy and lysosome inhibitor treatment to assess protein trafficking and degradation.
Main Results:
- EpCAM knockdown enhanced TJ formation, increased trans-epithelial electroresistance, and improved TJ resistance to disruption.
- EpCAM directly binds to claudin-7 and indirectly to claudin-1, with claudin-7 being crucial for EpCAM-claudin-1 association.
- EpCAM knockdown led to decreased claudin-7 and claudin-1 protein levels via lysosomal degradation, yet increased TJ accumulation of these claudins.
Conclusions:
- EpCAM modulates epithelial adhesion and TJ function by regulating the intracellular localization and degradation of claudin-7 and claudin-1.
- Physical interactions between EpCAM and claudins are essential for claudin stabilization.
- EpCAM's role in TJ regulation presents potential therapeutic implications for diseases involving epithelial barrier dysfunction.
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