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Concomitant alterations of desmosomes, adhesiveness, and diffusion through gap junction channels in a rat ovarian
L S Stein1, D W Stein, J Echols
1Department of Pediatrics, University of California, San Diego, La Jolla, California 92093.
Abstract:
Gap junctional intercellular communication (GJIC), desmosomes, and cell movement were evaluated in a rat ovarian epithelial cell model system which consisted of an immortalized clonal cell line (SIGC), a pSV3neotransfected clonal derivative (SV-SIGC), and a nude mouse SV-SIGC-tumor-derived cell line (T-SV-SIGC). Complementary ultrastructural, indirect immunofluorescence, and Western blot data identified a relatively small loss of desmosomes and associated cytokeratins in SV-SIGC compared to SIGC but a near total loss in T-SV-SIGC. SIGC and SV-SIGC migrated outward from monolayer-coated microcarrier beads as epithelial sheets, whereas in T-SV-SIGC there was dissociation and migration of individual fibroblastoid cells. GJIC was assessed by fluorescence recovery after photobleaching (gap FRAP) and equations based on Fick's first law of diffusion were derived to quantitatively compare GJIC of systems with different recovery equilibria after photobleaching. Taken together the data suggested that GJIC in SIGC was quantitatively reduced to similar levels by various conditions associated with reduced cell-cell adhesiveness including transformation to T-SV-SIGC, mitosis, and culture in low calcium medium. These results supported linkage between changes in desmosomal adhesiveness, cell movement, and GJIC.
Insights
Changes in desmosomes and cell adhesion impact gap junctional intercellular communication (GJIC) and cell movement in ovarian epithelial cells. Reduced cell-cell adhesion correlates with decreased GJIC and altered cell migration patterns.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Gap junctional intercellular communication (GJIC) is vital for tissue homeostasis.
- Desmosomes provide cell-cell adhesion and are crucial for epithelial integrity.
- Altered cell adhesion and communication are hallmarks of cancer progression.
Purpose of the Study:
- To investigate the relationship between desmosomes, cell movement, and GJIC in a rat ovarian epithelial cell model.
- To quantify changes in GJIC associated with alterations in cell-cell adhesion and transformation.
- To explore the impact of reduced desmosomal adhesion on cell migration.
Main Methods:
- Utilized an immortalized rat ovarian epithelial cell line (SIGC) and its derivatives (SV-SIGC, T-SV-SIGC).
- Employed ultrastructural analysis, indirect immunofluorescence, and Western blotting to assess desmosomes and cytokeratins.
- Quantified GJIC using fluorescence recovery after photobleaching (gap FRAP) and diffusion-based equations.
- Observed cell migration patterns from microcarrier beads.
Main Results:
- A progressive loss of desmosomes and associated cytokeratins was observed from SIGC to SV-SIGC and T-SV-SIGC.
- SIGC and SV-SIGC cells migrated as epithelial sheets, while T-SV-SIGC cells exhibited individual fibroblastoid migration.
- GJIC was quantitatively reduced in T-SV-SIGC cells and under conditions of reduced cell-cell adhesion (mitosis, low calcium).
Conclusions:
- Reduced desmosomal adhesiveness is linked to significant alterations in cell movement, transitioning from sheet to individual cell migration.
- GJIC is quantitatively reduced by factors diminishing cell-cell adhesion, including transformation and specific culture conditions.
- These findings support a functional linkage between desmosomal integrity, cell migration dynamics, and intercellular communication in ovarian epithelial cells.