title: Reduced Protein Expression of the Na+/Ca2++K+-Exchanger (SLC24A4) in Apical Plasma Membranes of Maturation Ameloblasts of Fluorotic Mice.
abstract: Exposure of forming enamel to fluoride results into formation of hypomineralized enamel. We tested whether enamel hypomineralization was caused by lower expression of the NCKX4/SLC24A4 Ca2+-transporter by ameloblasts. Three commercial antibodies against NCKX4 were tested on enamel organs of wild-type and Nckx4-null mice, one of which (a mouse monoclonal) was specific. This antibody gave a prominent staining of the apical plasma membranes of maturation ameloblasts, starting at early maturation. The layer of immuno-positive ameloblasts contained narrow gaps without immunostaining or with reduced staining. In fluorotic mouse incisors, the quantity of NCKX4 protein in ameloblasts as assessed by western blotting was not different from that in non-fluorotic ameloblasts. However, immunostaining of the apical plasma membranes of fluorotic ameloblasts was strongly reduced or absent suggesting that trafficking of NCKX4 to the apical membrane was strongly reduced. Exposure to fluoride may reduce NCKX4-mediated transport of Ca2+by maturation stage ameloblasts which delays ameloblast modulation and reduces enamel mineralization.
authors.affiliation: Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), MOVE Research Institute, University of Amsterdam and VU University Amsterdam, Gustav Mahlerlaan 3004, 1081LA, Amsterdam, The Netherlands. a.bronckers@acta.nl.
authors.forename: A L J J
authors.initials: AL
authors.lastname: Bronckers
authors.affiliation: Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), MOVE Research Institute, University of Amsterdam and VU University Amsterdam, Gustav Mahlerlaan 3004, 1081LA, Amsterdam, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Jalali
authors.affiliation: Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute and Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4Z6, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Lytton
mesh_terms: D000565:Ameloblasts / Q000378:metabolism*; D000566:Amelogenesis / Q000502:physiology; D000818:Animals; D017920:Antiporters / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D003743:Dental Enamel / Q000378:metabolism*; D005459:Fluorides / Q000378:metabolism; D008810:Mice, Inbred C57BL; D012982:Sodium, Dietary / Q000378:metabolism; D014074:Tooth Calcification / Q000502:physiology
chemical_list: D017920:Antiporters; C569957:Slc24a4 protein, mouse; D012982:Sodium, Dietary; D005459:Fluorides
keywords: Calcium; Enamel fluorosis; Mechanism; Null mutation; Transport