title: High-fluoride promoted phagocytosis-induced apoptosis in a matured ameloblast-like cell line.
abstract: Endocytosis and phagocytosis are important physiologic activities occurring during ameloblast differentiation. We have previously found that excess fluoride inhibited ameloblasts endocytotic functions. Here, we hypothesized that increasing amounts of fluoride may affect ameloblast phagocytotic function during their differentiation. Using cell culture, we first induced maturation of the mouse ameloblast-like LS8 cells by treatment with exogenous retinoic acid (RA) and dexamethasone (DEX). We measured their phagocytotic activity by fluorescent microscopy using a live cell visualization station. We found that ameloblast-like LS8 cells matured with RA/DEX treatment and the increasing amounts of fluoride demonstrated the up-regulated expression of the phagocytotic marker proteins, LAMP1 and CD68. A connection between phagocytosis and apoptosis was confirmed by the increased number of phagocytotic vacuole-like structures and the heterochromatin margination phenomenon observed in the RA/DEX with NaF treatment group. The increase in albumin uptake by ameloblasts was confirmed using whole organ culture of incisor tooth germs. Here, in fluoride treated tooth germs, mature canonical ameloblasts showed greater amounts of albumin uptake, which was accompanied by decreased expression of the anti-apoptosis marker, Bcl-2 along with up-regulated expression of CD68. From these observations, we inferred that high doses of fluoride may cause apoptosis by increasing the phagocytosis of protein particles in mature-stage ameloblasts and loss of Bcl-2 signals might be involved in this process.
authors.affiliation: State Key Laboratory of Military Stomatology, Department of Oral Biology, School of Stomatology, The Fourth Military Medical University, 145 Changle West Road, Xi'an, Shaanxi 710032, PR China.
authors.forename: Ting
authors.initials: T
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Military Stomatology, Department of Oral Biology, School of Stomatology, The Fourth Military Medical University, 145 Changle West Road, Xi'an, Shaanxi 710032, PR China.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Military Stomatology, Department of Oral Biology, School of Stomatology, The Fourth Military Medical University, 145 Changle West Road, Xi'an, Shaanxi 710032, PR China.
authors.forename: Dongdong
authors.initials: D
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Military Stomatology, Department of Oral Biology, School of Stomatology, The Fourth Military Medical University, 145 Changle West Road, Xi'an, Shaanxi 710032, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Hao
authors.affiliation: Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, CSA 142, Health Sciences Campus, Herman Ostrow School of Dentistry of USC, University of Southern California, 2250 Alcazar Street, Los Angeles, CA 90033, United States.
authors.forename: Malcolm L
authors.initials: ML
authors.lastname: Snead
authors.affiliation: State Key Laboratory of Military Stomatology, Department of Oral Biology, School of Stomatology, The Fourth Military Medical University, 145 Changle West Road, Xi'an, Shaanxi 710032, PR China. Electronic address: xhduan@fmmu.edu.cn.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Duan
mesh_terms: D000565:Ameloblasts / Q000166:cytology*; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D010587:Phagocytosis / Q000187:drug effects*; D012969:Sodium Fluoride / Q000494:pharmacology*; D000097382:CD68 Molecule; D052118:Lysosomal-Associated Membrane Protein 1
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D015415:Biomarkers; D051907:Lysosomal Membrane Proteins; D012969:Sodium Fluoride; C081026:CD68 protein, mouse; D000097382:CD68 Molecule; C052255:Lamp1 protein, mouse; D052118:Lysosomal-Associated Membrane Protein 1
keywords: Enamel; Endocytosis; Fluoride; Maturation; Phagocytosis