TRPM7-Mediated Calcium Transport in HAT-7 Ameloblasts |
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Authors: | Kristf Kdr Viktria Juhsz Anna Fldes Rbert Rcz Yan Zhang Heike Lchli Erzsbet Kat Lszl Kles Martin C Steward Pamela DenBesten Gbor Varga kos Zsembery |
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Affiliation: | 1.Department of Oral Biology, Semmelweis University, H-1089 Budapest, Hungary; (K.K.); (V.J.); (A.F.); (R.R.); (H.L.); (M.C.S.); (G.V.);2.Department of Orofacial Science, University of California, San Francisco, CA 94143, USA; (Y.Z.); (P.D.);3.Department of Pharmacology and Pharmacotherapy, Semmelweis University, H-1089 Budapest, Hungary; (E.K.); (L.K.);4.School of Medical Sciences, University of Manchester, Manchester M13 9PL, UK |
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Abstract: | 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. |
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Keywords: | TRPM7 channel protein enamel pH calcium entry magnesium amelogenesis store-operated calcium entry |
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