TRPM7-Mediated Calcium Transport in HAT-7 Ameloblasts.

Kristóf Kádár, Viktória Juhász, Anna Földes, Róbert Rácz, Yan Zhang, Heike Löchli, Erzsébet Kató, László Köles, Martin C Steward, Pamela DenBesten, Gábor Varga, Ákos Zsembery

International journal of molecular sciences 2021 Apr 13

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TRPM7 plays an important role in cellular Ca2+, Zn2+ and Mg2+ homeostasis. TRPM7 channels are abundantly expressed in ameloblasts and, in the absence of TRPM7, dental enamel is hypomineralized. The potential role of TRPM7 channels in Ca2+ transport during amelogenesis was investigated in the HAT-7 rat ameloblast cell line. The cells showed strong TRPM7 mRNA and protein expression. Characteristic TRPM7 transmembrane currents were observed, which increased in the absence of intracellular Mg2+ ([Mg2+]i), were reduced by elevated [Mg2+]i, and were inhibited by the TRPM7 inhibitors NS8593 and FTY720. Mibefradil evoked similar currents, which were suppressed by elevated [Mg2+]i, reducing extracellular pH stimulated transmembrane currents, which were inhibited by FTY720. Naltriben and mibefradil both evoked Ca2+ influx, which was further enhanced by the acidic intracellular conditions. The SOCE inhibitor BTP2 blocked Ca2+ entry induced by naltriben but not by mibefradil. Thus, in HAT-7 cells, TRPM7 may serves both as a potential modulator of Orai-dependent Ca2+ uptake and as an independent Ca2+ entry pathway sensitive to pH. Therefore, TRPM7 may contribute directly to transepithelial Ca2+ transport in amelogenesis.

Citation

Kristóf Kádár, Viktória Juhász, Anna Földes, Róbert Rácz, Yan Zhang, Heike Löchli, Erzsébet Kató, László Köles, Martin C Steward, Pamela DenBesten, Gábor Varga, Ákos Zsembery. TRPM7-Mediated Calcium Transport in HAT-7 Ameloblasts. International journal of molecular sciences. 2021 Apr 13;22(8)