PhD Scientific Days 2026

Dental Research

Functional characterization of ameloblast calcium transport proteins in polarized HAT-7 cells

Name of the presenter

Van-Weert, Szuzan

Institute/workplace of the presenter

Department of Oral Biology

Authors

Szuzan Van-Weert¹
1: Department of Oral Biology

Text of the abstract

Introduction: Dental enamel is formed by ameloblasts (specialized epithelial cells) through a multistep secretory process. It is associated with cyclic acidification of the matrix, suggesting a potential link between Ca2+ transport and local pH regulation. However, the exact mechanism and functional localization of Ca2+ transporters in these cells is not yet fully characterized.

Aims: Investigate the relationship between Ca2+ transport and local pH regulation during enamel formation, identify the transporters/channels involved, and determine their functional localization in polarized ameloblast-like HAT-7 cells.

Methods: HAT-7 cells were cultured on Transwell membrane under control and differentiating conditions. Monolayer formation was verified by transepithelial electrical resistance measurements. Intracellular Ca2+ ([Ca2+]i) responses were recorded using ratiometric Ca-imaging (Fura-2 AM). SOCE was activated by depletion of Ca2+ store with thapsigargin (100 nM). The effect of apical acidification (pH 6.3) on SOCE activation was examined.

Results: SOCE activation induced by irreversible SERCA inhibition under Ca2+-free conditions exhibited functional polarization, with significantly higher basolateral store-mediated Ca2+ influx (BL: 154.4 ± 14.1%; AP: 25.5 ± 4.6%; n=5 and n=4, p<0.001). Apical acidification significantly reduced the basolateral SOCE-mediated [Ca2+]i peak (pH 7.4: 154.4 ± 14.1%; pH 6.3: 95.17 ± 19.4%; n=5, p<0.05).

Conclusion: Ca2+ uptake mechanisms exhibited significant functional polarization: SOCE activity was predominant at the basolateral membrane. The [Ca2+]i increase was sensitive to apical extracellular acidification. Our model system could provide a suitable model for studying ameloblast vectorial transport including its specific transporters and the effects of local pH changes on this process.

Funding: This work was supported by the University Research Scholarship Programme (EKÖP) through Semmelweis University (grant identifier: EKÖP-2025-406).