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Intercellular junctions in oral epithelial cells: ultrastructural and immunological aspects
Alberto Gasparoni1, Christopher A Squier, Luciano Fonzi
1Dipartimento di Farmacologia G. Segre, Sezione di Anatomia, Nuovi Istituti Biologici San Miniato, Università degli Studi di Siena, Siena.
Summary
Increased calcium concentration promotes intercellular junction formation in human gingival cells. This affects cell shape and the localization of key proteins like E-cadherin and beta-catenin, influencing cell adhesion.
Area of Science:
- Cell Biology
- Epithelial Cell Biology
- Biochemistry
Background:
- Intercellular junctions are crucial for epithelial cell differentiation.
- Calcium ions (Ca++) play a role in activating molecular cascades for cell differentiation.
- The precise role of Ca++ concentration in modulating intercellular junction morphology and biochemistry in oral epithelial cells requires further investigation.
Purpose of the Study:
- To test the hypothesis that Ca++ concentration influences morphological and biochemical changes in intercellular junctions of cultured human gingival cells.
- To investigate the role of the E-cadherin/beta-catenin complex in Ca++-mediated intercellular junction formation.
Main Methods:
- Cultured human oral gingival cells were exposed to varying Ca++ concentrations (0.3 mM and 1.8 mM).
- Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to examine cell morphology and junction development.
- Confocal laser scanning microscopy (CLSM) assessed the localization of E-cadherin and beta-catenin, with and without E-cadherin blocking antibodies.
Main Results:
- Cells cultured at physiological Ca++ concentrations (1.8 mM) exhibited increased microvilli size and a higher number of intercellular junctions compared to those at 0.3 mM Ca++.
- Desmosome-like junctions were observed in cells grown in 1.8 mM Ca++ but not in 0.3 mM Ca++.
- E-cadherin and beta-catenin localized to the membrane within hours, facilitating cell adhesion and polygonal cell shape; blocking adhesion resulted in round cells and altered beta-catenin localization.
Conclusions:
- Elevated Ca++ concentration induces significant biochemical and morphological alterations at the cell membrane level in human oral epithelial cells.
- These Ca++-induced changes are critical for the establishment and development of intercellular junctions.
- The E-cadherin/beta-catenin complex is essential for mediating Ca++-dependent cell adhesion and junction formation.