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Claudin-4 localization in epithelial ovarian cancer
Margaret C Neville1, Patricia G Webb2, Heidi K Baumgartner3
1Departments of Obstetrics and Gynecology and Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, 80845, USA.
Heliyon
|October 14, 2022
Summary
Claudin-4, a protein overexpressed in cancers, is found in the Golgi and near cell junctions in ovarian cancer cells. Its specific cellular location provides insights into its function and interactions in tumors.
Area of Science:
- Cell Biology
- Cancer Research
- Molecular Biology
Background:
- Claudin-4 is a protein structurally similar to classic claudins found in cell-cell junctions.
- Overexpression of claudin-4 is common in epithelial cancers, but its precise localization within these cells remains largely unstudied.
- Understanding claudin-4's cellular location is crucial for deciphering its role in cancer progression.
Purpose of the Study:
- To investigate the subcellular localization of claudin-4 in the OVCAR3 ovarian cancer cell line.
- To determine the relationship between native and phosphorylated claudin-4.
- To explore the association of claudin-4 with cellular compartments like the Golgi and focal adhesions.
Main Methods:
- Immunohistochemistry was employed to visualize claudin-4 staining patterns.
- BioID proximity labeling technology was utilized to identify claudin-4 interacting proteins and its localization.
- OVCAR3 ovarian cancer cells were used as a model system, including conditions with partial claudin-4 knockdown and during cell division.
Main Results:
- Claudin-4 was detected in the perinuclear region, plasma membranes, and cytoplasmic puncta.
- Native claudin-4 and phosphorylated claudin-4 showed distinct localizations, with the latter found in focal adhesions.
- BioID confirmed significant claudin-4 localization to the Golgi compartment, including dispersed Golgi structures.
- Claudin-4 was observed near cell-cell junctions but did not appear to form tight junctions.
- Claudin-4, GM130 (Golgi marker), and Notch2 (plasma membrane receptor) were co-localized in dispersed Golgi during cell division.
Conclusions:
- Claudin-4 exhibits a complex subcellular distribution in ovarian cancer cells, primarily within the Golgi and near plasma membranes.
- The distinct localization of native and phosphorylated claudin-4 suggests differential functions.
- These findings define the cellular architecture of claudin-4, offering a foundation for understanding its role and interactions in tumor biology.
