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Okamoto M, Yamashita S, Memida T, Mendonca M, Brueckner S, Nakamura S, Shindo S, Achong-Bowe R, Thompson J, Han X, Kawai T, Suzuki M. Microhardness Measurements on Tooth and Alveolar Bone in Rodent Oral Disease Models. J Vis Exp 2024:10.3791/66583. [PMID: 38738893 PMCID: PMC11221687 DOI: 10.3791/66583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024] Open
Abstract
The mechanical property, microhardness, is evaluated in dental enamel, dentin, and bone in oral disease models, including dental fluorosis and periodontitis. Micro-CT (µCT) provides 3D imaging information (volume and mineral density) and scanning electron microscopy (SEM) produces microstructure images (enamel prism and bone lacuna-canalicular). Complementarily to structural analysis by µCT and SEM, microhardness is one of the informative parameters to evaluate how structural changes alter mechanical properties. Despite being a useful parameter, studies on microhardness of alveolar bone in oral diseases are limited. To date, divergent microhardness measurement methods have been reported. Since microhardness values vary depending on the sample preparation (polishing and flat surface) and indentation sites, diverse protocols can cause discrepancies among studies. Standardization of the microhardness protocol is essential for consistent and accurate evaluation in oral disease models. In the present study, we demonstrate a standardized protocol for microhardness analysis in tooth and alveolar bone. Specimens used are as follows: for the dental fluorosis model, incisors were collected from mice treated with/without fluoride-containing water for 6 weeks; for ligature-induced periodontal bone resorption (L-PBR) model, alveolar bones with periodontal bone resorption were collected from mice ligated on the maxillary 2nd molar. At 2 weeks after the ligation, the maxilla was collected. Vickers hardness was analyzed in these specimens according to the standardized protocol. The protocol provides detailed materials and methods for resin embedding, serial polishing, and indentation sites for incisors and alveolar. To the best of our knowledge, this is the first standardized microhardness protocol to evaluate the mechanical properties of tooth and alveolar bone in rodent oral disease models.
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Affiliation(s)
- Motoki Okamoto
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Shohei Yamashita
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Takumi Memida
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Melanie Mendonca
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Susanne Brueckner
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Shin Nakamura
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Satoru Shindo
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Ria Achong-Bowe
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Jeffrey Thompson
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Xiaozhe Han
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Toshihisa Kawai
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University
| | - Maiko Suzuki
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University;
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Jinyi L, Keyu Y, Shanshan D, Shuyang H, Ruirui L, Qingyu G, Fei L. ERS Mediated by GRP-78/PERK/CHOP Signaling Is Involved in Fluoride-Induced Ameloblast Apoptosis. Biol Trace Elem Res 2024; 202:1103-1114. [PMID: 37410266 DOI: 10.1007/s12011-023-03746-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 06/24/2023] [Indexed: 07/07/2023]
Abstract
Fluoride can be widely ingested from the environment, and its excessive intake could result in adverse effects. Dental fluorosis is an early sign of fluoride toxicity which can cause esthetic and functional problems. Though apoptosis in ameloblasts is one of the potential mechanisms, the specific signal cascade is in-conclusive. High-throughput sequencing and molecular biological techniques were used in this study to explore the underlying pathogenesis of dental fluorosis, for its prevention and treatment. A fluorosis cell model was established. Viability and apoptosis rate of mouse ameloblast-derived cell line (LS8 cells) was measured using cell counting kit-8 (CCK-8) assay and flow cytometry analysis. Cells were harvested with or without 2-mM sodium fluoride (NaF) stimulation for high-throughput sequencing. Based on the sequencing data, subcellular structures, endoplasmic reticulum stress (ERS), and apoptosis related biomarkers were verified using transmission electron microscopy, quantitative real-time polymerase chain reaction, and Western blotting techniques. Expression of ERS markers, apoptosis related proteins, and enamel formation enzymes were detected using Western blotting after addition of 4-phenylbutyrate (4-PBA). NaF-inhibited LS8 cells displayed time- and dose- dependent viability. Additionally, apoptosis and morphological changes were observed. RNA-sequencing data showed that protein processing in endoplasmic reticulum was obviously affected. ERS and apoptosis were induced by excessive NaF. Downregulation of kallikrein-related peptidase 4 (KLK4) was also observed. Inhibition of ERS by 4-PBA rescued the apoptotic and functional protein changes in cells. Excessive fluoride induces apoptosis by activating ERS, which is mediated by GRP-78/PERK/CHOP signaling. Key proteinase is present in maturation-stage enamel; KLK4 was also affected by fluoride, but rescued by 4-PBA. This study presents a possibility for therapeutic strategies for dental fluorosis, while further exploration is required.
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Affiliation(s)
- Li Jinyi
- Key laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China
- Department of Pediatric Dentistry, College of Stomatology, Xi'an Jiaotong University, Xi Wu Road No.98, Xi'an 710004, 710041, People's Republic of China
| | - Yang Keyu
- National Regional Children's Medical Center (Northwest), Xi'an Children's Hospital, Affiliated Children's Hospital of Xi'an Jiaotong University, Xi'an, 710003, People's Republic of China
| | - Dai Shanshan
- Key laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China
- Department of Pediatric Dentistry, College of Stomatology, Xi'an Jiaotong University, Xi Wu Road No.98, Xi'an 710004, 710041, People's Republic of China
| | - He Shuyang
- Faculty of dentistry, The university of Hong Kong, Hong Kong, SAR, People's Republic of China
| | - Liu Ruirui
- Key laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China
- Department of Prosthodontics, College of Stomatology, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China
| | - Guo Qingyu
- Key laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China.
- Department of Pediatric Dentistry, College of Stomatology, Xi'an Jiaotong University, Xi Wu Road No.98, Xi'an 710004, 710041, People's Republic of China.
| | - Liu Fei
- Key laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China.
- Department of Pediatric Dentistry, College of Stomatology, Xi'an Jiaotong University, Xi Wu Road No.98, Xi'an 710004, 710041, People's Republic of China.
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3
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González-Casamada C, Nevarez-Rascón M, Nevarez-Rascón A, González-Galván M, Isiordia-Espinoza MA, Bologna-Molina R, Sánchez-Pérez L, Molina-Frechero N. Single Nucleotide Polymorphisms and Dental Fluorosis: A Systematic Review. Dent J (Basel) 2022; 10:211. [PMID: 36354656 PMCID: PMC9689045 DOI: 10.3390/dj10110211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/29/2022] [Accepted: 11/01/2022] [Indexed: 12/01/2023] Open
Abstract
Genetic factors contribute to susceptibility and resistance to fluoride exposure. The aim of this systematic review was to identify alleles/genotypes of single nucleotide polymorphisms (SNPs) associated with dental fluorosis (DF) and to identify them as protective or risk factors. PubMed, ScienceDirect, Cochrane Library, Scopus and Web of Science were searched for articles; the last search was performed in August 2022. Human studies that analyzed the relationship between SNPs and DF published in English were included; systematic reviews and meta-analyses were excluded. Methodological quality was graded using the Joanna Briggs Institute checklist and risk of bias was assessed using the Cochrane Collaboration's tool. Eighteen articles were included, 44% of which showed high methodological quality and data from 5,625 participants aged 6 to 75 years were analyzed. The SNPs COL1A2, ESR2, DLX1, DLX2, AMBN, TUFT1, TFIP11, miRNA17, and SOD2 were considered risk factors, and ESR1, MMP20, and ENAM were considered protective factors. In conclusion, there are alleles and genotypes of different single nucleotide polymorphisms involved in increasing or decreasing the risk of developing dental fluorosis.
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Affiliation(s)
- Carlos González-Casamada
- Health Care Department, Autonomous Metropolitan University Xochimilco, Mexico City 04960, Mexico
| | | | | | | | - Mario Alberto Isiordia-Espinoza
- Institute of Research in Medical Sciences, Department of Clinics, Los Altos University Center, University of Guadalajara, Tepatitlan de Morelos 47650, Jalisco, Mexico
| | - Ronell Bologna-Molina
- Research Department, School of Dentistry, Juarez University of the Durango State, Durango 34000, Mexico
- Molecular Pathology Area, School of Dentistry, University of the Republic, Montevideo 11200, Uruguay
| | - Leonor Sánchez-Pérez
- Division of Biological and Health Sciences, Autonomous Metropolitan University Xochimilco, Mexico City 04960, Mexico
| | - Nelly Molina-Frechero
- Division of Biological and Health Sciences, Autonomous Metropolitan University Xochimilco, Mexico City 04960, Mexico
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Yang J, Huang T, Yao J, Zhang J, Bai G, Chen Z, Tu C. Sulphur dioxide and fluoride co-exposure induce incisor hypomineralization and amelogenin upregulation via YAP/RUNX2 signaling pathway. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 245:114106. [PMID: 36155332 DOI: 10.1016/j.ecoenv.2022.114106] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/17/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Sulphur dioxide (SO2) and fluoride are among the most common environmental pollutants affecting human health, and both co-exist in areas predominantly consuming coal. It is vital to analyse the combined toxicity of SO2 and fluoride, and their effects on health and the underlying mechanisms of their co-exposure have not yet been adequately assessed. In the present study, we used ICR mice and LS8 cells to investigate the toxicity of SO2 and fluoride exposure to the enamel, alone or in combination. Factorial design analysis was used to reveal the combined toxicity in vitro and in vivo. Co-exposure to SO2 and fluoride exacerbated enamel injury, resulting in more severe hypomineralization of incisor, and enamel structure disorders in mice, and could induce the accumulation of protein residue in the matrix of the enamel. Amelogenin expression was increased upon exposure to SO2 and fluoride, but enamel matrix proteases were not affected. Consistent with our in vivo results, co-exposure of SO2 and fluoride aggravated amelogenin expression in LS8 cells, and increased the YAP and RUNX2 levels. Co-exposure to SO2 and fluoride resulted in greater toxicity than individual exposure, both in vitro and in vivo, indicating that residents of areas exposed to SO2 and fluoride may have an increased risk of developing enamel damage.
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Affiliation(s)
- Junlin Yang
- School of Public Health, Guizhou Medical University, Guian New Region, China; The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Tongtong Huang
- School of Public Health, Guizhou Medical University, Guian New Region, China
| | - Jie Yao
- School of Public Health, Guizhou Medical University, Guian New Region, China
| | - Jianghui Zhang
- School of Public Health, Guizhou Medical University, Guian New Region, China
| | - Guohui Bai
- Key Laboratory of Oral Disease Research, School of Stomatology, Zunyi Medical University, Zunyi, China
| | - Zheng Chen
- School of Public Health, Guizhou Medical University, Guian New Region, China
| | - Chenglong Tu
- Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guian New Region, China; Toxicity Testing Center of Guizhou Medical University, Guiyang, China.
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5
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Saghiri MA, Sheibani N, Kawai T, Nath D, Dadvand S, Amini S, Vakhnovetsky J, Morgano SM. Diabetes Negatively Affects Tooth Enamel and Dentine Microhardness: An In-vivo Study. Arch Oral Biol 2022; 139:105434. [DOI: 10.1016/j.archoralbio.2022.105434] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/25/2022] [Accepted: 04/14/2022] [Indexed: 11/16/2022]
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Gil-Bona A, Bidlack FB. Tooth Enamel and its Dynamic Protein Matrix. Int J Mol Sci 2020; 21:ijms21124458. [PMID: 32585904 PMCID: PMC7352428 DOI: 10.3390/ijms21124458] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/19/2020] [Accepted: 06/20/2020] [Indexed: 12/12/2022] Open
Abstract
Tooth enamel is the outer covering of tooth crowns, the hardest material in the mammalian body, yet fracture resistant. The extremely high content of 95 wt% calcium phosphate in healthy adult teeth is achieved through mineralization of a proteinaceous matrix that changes in abundance and composition. Enamel-specific proteins and proteases are known to be critical for proper enamel formation. Recent proteomics analyses revealed many other proteins with their roles in enamel formation yet to be unraveled. Although the exact protein composition of healthy tooth enamel is still unknown, it is apparent that compromised enamel deviates in amount and composition of its organic material. Why these differences affect both the mineralization process before tooth eruption and the properties of erupted teeth will become apparent as proteomics protocols are adjusted to the variability between species, tooth size, sample size and ephemeral organic content of forming teeth. This review summarizes the current knowledge and published proteomics data of healthy and diseased tooth enamel, including advancements in forensic applications and disease models in animals. A summary and discussion of the status quo highlights how recent proteomics findings advance our understating of the complexity and temporal changes of extracellular matrix composition during tooth enamel formation.
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Affiliation(s)
- Ana Gil-Bona
- The Forsyth Institute, Cambridge, MA 02142, USA
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
- Correspondence: (A.G.-B.); (F.B.B.)
| | - Felicitas B. Bidlack
- The Forsyth Institute, Cambridge, MA 02142, USA
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
- Correspondence: (A.G.-B.); (F.B.B.)
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7
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Sánchez LM, Ubios ÁM. Alterations in odontogenesis and tooth eruption resulting from exposure to hexavalent chromium in suckling animals. Int J Paediatr Dent 2020; 30:35-41. [PMID: 31461794 DOI: 10.1111/ipd.12573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/03/2019] [Accepted: 08/22/2019] [Indexed: 11/26/2022]
Abstract
BACKGROUND Heavy metals including Cr VI are present in inadequately treated effluents that contaminate drinking water. Hence, Cr VI exposure can affect children through intake of breast milk from an exposed mother or bottle-feeding formula prepared with contaminated water. To date, there are no reports on the effects of Cr VI exposure on tooth formation processes concomitant to tooth eruption. AIM To study the effect of Cr VI exposure on tooth tissue formation in suckling Wistar rats by assessing dental tissues at different stages of tooth eruption. DESIGN Experimental animals received 12.5 mg/kg body weight/day of a potassium dichromate solution by gavage; control animals were similarly administered an equivalent volume of saline solution. Each group was divided into three subsets according to age at euthanasia: 9, 15, and 23 days. Dental formation was analysed histologically and histomorphometrically. STATISTICAL ANALYSIS Student's t test; P < .05. RESULTS Cr VI-exposed animals showed a delay in mineralized crown and root tissue formation. These findings are directly associated with the observed delay in tooth eruption. CONCLUSION Our findings show the importance of monitoring drinking water levels of toxic substances, since exposure during early childhood can alter tooth formation, growth, and development.
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Affiliation(s)
- Luciana Marina Sánchez
- Universidad de Buenos Aires, Facultad de Odontología, Cátedra de Histología y Embriología, Buenos Aires, Argentina
| | - Ángela Matilde Ubios
- Universidad de Buenos Aires, Facultad de Odontología, Cátedra de Histología y Embriología, Buenos Aires, Argentina
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8
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Abstract
Chronic fluoride overexposure can cause dental fluorosis. Dental fluorosis is characterized by porous and soft enamel that is vulnerable to erosion and decay. Animal models often contribute to clinical applications by addressing pathogenic questions of disease. To study dental fluorosis, rodent models have been employed because rodent incisors erupt continuously and every stage of enamel development is present along the length of the rodent incisor. Here we present a protocol to induce dental fluorosis in mouse and rat and describe the procedure for extraction of stage specific enamel organ from rat mandibular incisors.
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9
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Yamazaki H, Tran B, Beniash E, Kwak SY, Margolis HC. Proteolysis by MMP20 Prevents Aberrant Mineralization in Secretory Enamel. J Dent Res 2019; 98:468-475. [PMID: 30744480 DOI: 10.1177/0022034518823537] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The present study was conducted to investigate the role of proteolysis by matrix metalloproteinase 20 (MMP20) in regulating the initial formation of the enamel mineral structure during the secretory stage of amelogenesis, utilizing Mmp20-null mice that lack this essential protease. Ultrathin sagittal sections of maxillary incisors from 8-wk-old wild-type (WT), Mmp20-null (KO), and heterozygous (HET) littermates were prepared. Secretory-stage enamel ultrastructures from each genotype as a function of development were compared using transmission electron microscopy, selected area electron diffraction, and Raman microspectroscopy. Characteristic rod structures observed in WT enamel exhibited amorphous features in newly deposited enamel, which subsequently transformed into apatite-like crystals in older enamel. Surprisingly, initial mineral formation in KO enamel was found to proceed in the same manner as in the WT. However, soon after a rod structure began to form, large plate-like crystals appeared randomly within the developing KO enamel layer. As development continued, observed plate-like crystals became dominant and obscured the appearance of the enamel rod structure. Upon formation of these plate-like crystals, the KO enamel layer stopped growing in thickness, unlike WT and HET enamel layers that continued to grow at the same rate. Raman results indicated that Mmp20-KO enamel contains a significant portion of octacalcium phosphate, unlike WT enamel. Although normal in all other respects, large, randomly dispersed mineral crystals were observed in secretory HET enamel, although to a lesser extent than that seen in KO enamel, indicating that the level of MMP20 expression has a proportional effect on suppressing aberrant mineral formation. In conclusion, we found that proteolysis of extracellular enamel matrix proteins by MMP20 is not required for the initial development of the enamel rod structure during the early secretory stage of amelogenesis. Proteolysis by MMP20, however, is essential for the prevention of abnormal crystal formation during amelogenesis.
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Affiliation(s)
- H Yamazaki
- 1 The Forsyth Institute, Cambridge, MA, USA.,2 Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
| | - B Tran
- 3 Simmons College, Boston, MA, USA
| | - E Beniash
- 4 Center for Craniofacial Regeneration, Department of Oral Biology, University of Pittsburgh School of Dental Medicine, Pittsburgh, PA, USA
| | - S Y Kwak
- 1 The Forsyth Institute, Cambridge, MA, USA.,2 Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
| | - H C Margolis
- 1 The Forsyth Institute, Cambridge, MA, USA.,2 Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
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Romualdo PC, Pucinelli CM, Tannure PN, Nelson-Filho P, Segato RAB, Brancher JA, Magalhães NL, Costa MDC, Antunes LAA, Antunes LS, Buzalaf MAR, Charone S, Küchler EC. Evaluation of genetic polymorphisms in MMP2, MMP9 and MMP20 in Brazilian children with dental fluorosis. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2019; 66:104-108. [PMID: 30639979 DOI: 10.1016/j.etap.2018.12.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 06/09/2023]
Abstract
Recent studies suggested that genetics contribute to differences in dental fluorosis (DF) susceptibility among individuals having the same environmental exposure. This study evaluated if MMP2, MMP9 and MMP20 are expressed during enamel development and assessed the association between polymorphisms in these genes with DF. Mice susceptible and resistant to DF were used to evaluate if MMPs were candidate genes for DF. The animals received fluoride and their enamels were used for immunohistochemistry. Additionally, 481 subjects from a city with fluoridation of public water supplies were recruited. Genotyping was performed using real time PCR. Allele/genotype frequencies were compared between groups. MMP2, MMP9 and MMP20 immunostaining was detected in both animal groups. DF was observed in 22.4% of the subjects. A borderline association was observed in MMP2 (rs243865), MMP9 (rs17576) and in MMP20 (rs1784418) (p = 0.06, p = 0.08 and p = 0.06 respectively). Briefly, MMPs were expressed during enamel maturation and genetic polymorphisms were not associated with DF.
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Affiliation(s)
- Priscilla Coutinho Romualdo
- Department of Pediatric Dentistry, Ribeirão Preto Dental School, USP - University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Carolina Maschietto Pucinelli
- Department of Pediatric Dentistry, Ribeirão Preto Dental School, USP - University of São Paulo, Ribeirão Preto, SP, Brazil
| | | | - Paulo Nelson-Filho
- Department of Pediatric Dentistry, Ribeirão Preto Dental School, USP - University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Raquel Assed Bezerra Segato
- Department of Pediatric Dentistry, Ribeirão Preto Dental School, USP - University of São Paulo, Ribeirão Preto, SP, Brazil
| | | | - Nilza Letícia Magalhães
- Department of Pediatric Dentistry, Ribeirão Preto Dental School, USP - University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Marcelo de Castro Costa
- Department of Pediatric Dentistry and Orthodontics, School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | | | | | | | - Senda Charone
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Brazil
| | - Erika Calvano Küchler
- Department of Pediatric Dentistry, Ribeirão Preto Dental School, USP - University of São Paulo, Ribeirão Preto, SP, Brazil.
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11
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Li J, Wang P, Gao J, Fei X, Liu Y, Ruan J. NaF Reduces KLK4 Gene Expression by Decreasing Foxo1 in LS8 Cells. Biol Trace Elem Res 2018; 186:498-504. [PMID: 29633120 DOI: 10.1007/s12011-018-1325-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 03/22/2018] [Indexed: 10/17/2022]
Abstract
Decreased expression and increased phosphorylation of Forkhead box o1 (Foxo1) in ameloblasts were observed both in vivo and in vitro when treated by fluoride. The present study aims to investigate the possible relationship between Foxo1 and enamel matrix proteinases, matrix metalloproteinase 20 (MMP20), and kallikrein 4 (KLK4), in NaF-treated ameloblasts. Ameloblast-like cells (LS8 cells) were exposed to NaF at selected concentration (0/2 mM) for 24 h. Gene overexpression and silencing experiments were used to up- and down-regulate Foxo1 expression. The expression levels of Foxo1, MMP20, and KLK4 were detected by quantitative real-time PCR and western blot. Dual luciferase reporter assay was performed to evaluate the regulation of Foxo1 on the transcriptional activity of KLK4 promoter. The results showed that KLK4 expression was decreased in LS8 cells treated by NaF, while MMP20 expression was not changed. Foxo1 activation led to significantly up-regulation of KLK4 in LS8 cells under NaF condition. Knockout of Foxo1 markedly decreased klk4 expression in mRNA level, and intensified inhibition occurred in LS8 cells when combined with NaF treatment. However, the variation trend of MMP20 was not clear. Dual luciferase reporter assay showed that Foxo1 activation enhanced the transcriptional activity of KLK4 promoter. These findings suggest that the decrease of Foxo1 expression induced by high fluoride was a cause for low KLK4 expression.
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Affiliation(s)
- Juedan Li
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China
- Department of General Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China
| | - Peng Wang
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China
| | - Jianghong Gao
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China
- Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China
| | - Xiuzhi Fei
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China
- Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China
| | - Yan Liu
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China
- Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China
| | - Jianping Ruan
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China.
- Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, People's Republic of China.
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12
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Suzuki M, Everett ET, Whitford GM, Bartlett JD. 4-phenylbutyrate Mitigates Fluoride-Induced Cytotoxicity in ALC Cells. Front Physiol 2017; 8:302. [PMID: 28553235 PMCID: PMC5425599 DOI: 10.3389/fphys.2017.00302] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/25/2017] [Indexed: 12/13/2022] Open
Abstract
Chronic fluoride over-exposure during pre-eruptive enamel development can cause dental fluorosis. Severe dental fluorosis is characterized by porous, soft enamel that is vulnerable to erosion and decay. The prevalence of dental fluorosis among the population in the USA, India and China is increasing. Other than avoiding excessive intake, treatments to prevent dental fluorosis remain unknown. We previously reported that high-dose fluoride induces endoplasmic reticulum (ER) stress and oxidative stress in ameloblasts. Cell stress induces gene repression, mitochondrial damage and apoptosis. An aromatic fatty acid, 4-phenylbutyrate (4PBA) is a chemical chaperone that interacts with misfolded proteins to prevent ER stress. We hypothesized that 4PBA ameliorates fluoride-induced ER stress in ameloblasts. To determine whether 4PBA protects ameloblasts from fluoride toxicity, we analyzed gene expression of Tgf-β1, Bcl2/Bax ratio and cytochrome-c release in vitro. In vivo, we measured fluorosis levels, enamel hardness and fluoride concentration. Fluoride treated Ameloblast-lineage cells (ALC) had decreased Tgf-β1 expression and this was reversed by 4PBA treatment. The anti-apoptotic Blc2/Bax ratio was significantly increased in ALC cells treated with fluoride/4PBA compared to fluoride treatment alone. Fluoride treatment induced cytochrome-c release from mitochondria into the cytosol and this was inhibited by 4PBA treatment. These results suggest that 4PBA mitigates fluoride-induced gene suppression, apoptosis and mitochondrial damage in vitro. In vivo, C57BL/6J mice were provided fluoridated water for six weeks with either fluoride free control-chow or 4PBA-containing chow (7 g/kg 4PBA). With few exceptions, enamel microhardness, fluorosis levels, and fluoride concentrations of bone and urine did not differ significantly between fluoride treated animals fed with control-chow or 4PBA-chow. Although 4PBA mitigated high-dose fluoride toxicity in vitro, a diet rich in 4PBA did not attenuate dental fluorosis in rodents. Perhaps, not enough intact 4PBA reaches the rodent ameloblasts necessary to reverse the effects of fluoride toxicity. Further studies will be required to optimize protocols for 4PBA administration in vivo in order to evaluate the effect of 4PBA on dental fluorosis.
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Affiliation(s)
- Maiko Suzuki
- Division of Biosciences, College of Dentistry, The Ohio State UniversityColumbus, OH, USA
| | - Eric T Everett
- Department of Pediatric Dentistry and The Carolina Center for Genome Sciences, University of North CarolinaChapel Hill, NC, USA
| | - Gary M Whitford
- Department of Oral Biology, College of Dental Medicine, Georgia Regents UniversityAugusta, GA, USA
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State UniversityColumbus, OH, USA
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13
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Pugach MK, Gibson CW. Analysis of enamel development using murine model systems: approaches and limitations. Front Physiol 2014; 5:313. [PMID: 25278900 PMCID: PMC4166228 DOI: 10.3389/fphys.2014.00313] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 08/01/2014] [Indexed: 11/24/2022] Open
Abstract
A primary goal of enamel research is to understand and potentially treat or prevent enamel defects related to amelogenesis imperfecta (AI). Rodents are ideal models to assist our understanding of how enamel is formed because they are easily genetically modified, and their continuously erupting incisors display all stages of enamel development and mineralization. While numerous methods have been developed to generate and analyze genetically modified rodent enamel, it is crucial to understand the limitations and challenges associated with these methods in order to draw appropriate conclusions that can be applied translationally, to AI patient care. We have highlighted methods involved in generating and analyzing rodent enamel and potential approaches to overcoming limitations of these methods: (1) generating transgenic, knockout, and knockin mouse models, and (2) analyzing rodent enamel mineral density and functional properties (structure and mechanics) of mature enamel. There is a need for a standardized workflow to analyze enamel phenotypes in rodent models so that investigators can compare data from different studies. These methods include analyses of gene and protein expression, developing enamel histology, enamel pigment, degree of mineralization, enamel structure, and mechanical properties. Standardization of these methods with regard to stage of enamel development and sample preparation is crucial, and ideally investigators can use correlative and complementary techniques with the understanding that developing mouse enamel is dynamic and complex.
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Affiliation(s)
- Megan K Pugach
- Department of Mineralized Tissue Biology, The Forsyth Institute, Harvard School of Dental Medicine, Harvard University Cambridge, MA, USA
| | - Carolyn W Gibson
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA, USA
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14
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Suzuki M, Sierant ML, Antone JV, Everett ET, Whitford GM, Bartlett JD. Uncoupling protein-2 is an antioxidant that is up-regulated in the enamel organ of fluoride-treated rats. Connect Tissue Res 2014; 55 Suppl 1:25-8. [PMID: 25158175 PMCID: PMC4145607 DOI: 10.3109/03008207.2014.923854] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Dental fluorosis is characterized by subsurface hypomineralization and retention of enamel matrix proteins. Fluoride (F(-)) exposure generates reactive oxygen species (ROS) that can cause endoplasmic reticulum (ER)-stress. We therefore screened oxidative stress arrays to identify genes regulated by F(-) exposure. Vitamin E is an antioxidant so we asked if a diet high in vitamin E would attenuate dental fluorosis. Maturation stage incisor enamel organs (EO) were harvested from F(-)-treated rats and mice were assessed to determine if vitamin E ameliorates dental fluorosis. Uncoupling protein-2 (Ucp2) was significantly up-regulated by F(-) (∼1.5 & 2.0 fold for the 50 or 100 ppm F(-) treatment groups, respectively). Immunohistochemical results on maturation stage rat incisors demonstrated that UCP2 protein levels increased with F(-) treatment. UCP2 down-regulates mitochondrial production of ROS, which decreases ATP production. Thus, in addition to reduced protein translation caused by ER-stress, a reduction in ATP production by UCP2 may contribute to the inability of ameloblasts to remove protein from the hardening enamel. Fluoride-treated mouse enamel had significantly higher quantitative fluorescence (QF) than the untreated controls. No significant QF difference was observed between control and vitamin E-enriched diets within a given F(-) treatment group. Therefore, a diet rich in vitamin E did not attenuate dental fluorosis. We have identified a novel oxidative stress response gene that is up-regulated in vivo by F(-) and activation of this gene may adversely affect ameloblast function.
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Affiliation(s)
- Maiko Suzuki
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA, USA
| | - Megan L. Sierant
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA, USA
| | - Jerry V. Antone
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA, USA
| | - Eric T. Everett
- Department of Pediatric Dentistry and The Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Gary M. Whitford
- Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA, USA
| | - John D. Bartlett
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA, USA
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15
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Suzuki M, Shin M, Simmer JP, Bartlett JD. Fluoride affects enamel protein content via TGF-β1-mediated KLK4 inhibition. J Dent Res 2014; 93:1022-7. [PMID: 25074495 DOI: 10.1177/0022034514545629] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Dental fluorosis is caused by chronic high-level fluoride (F(-)) exposure during enamel development, and fluorosed enamel has a higher than normal protein content. Matrix metalloproteinase 20 cleaves enamel matrix proteins during the secretory stage, and KLK4 further cleaves these proteins during the maturation stage so that the proteins can be reabsorbed from the hardening enamel. We show that transforming growth factor β1 (TGF-β1) can induce Klk4 expression, and we examine the effect of F(-) on TGF-β1 and KLK4 expression. We found that in vivo F(-) inhibits Klk4 but not Mmp20 transcript levels. LacZ-C57BL/6-Klk4 (+/LacZ) mice have LacZ inserted in frame at the Klk4 translation initiation site so that the endogenous Klk4 promoter drives LacZ expression in the same temporal/spatial way as it does for Klk4. KLK4 protein levels in rat enamel and β-galactosidase staining in LacZ-C57BL/6-Klk4 (+/LacZ) mouse enamel were both significantly reduced by F(-) treatment. Since TGF-β1 induces KLK4 expression, we tested and found that F(-) significantly reduced Tgf-β1 transcript levels in rat enamel organ. These data suggest that F(-)-mediated downregulation of TGF-β1 expression contributes to reduced KLK4 protein levels in fluorosed enamel and provides an explanation for why fluorosed enamel has a higher than normal protein content.
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Affiliation(s)
- M Suzuki
- Department of Mineralized Tissue Biology, The Forsyth Institute, Cambridge, MA, USA, and Harvard School of Dental Medicine, Boston, MA, USA
| | - M Shin
- Department of Mineralized Tissue Biology, The Forsyth Institute, Cambridge, MA, USA, and Harvard School of Dental Medicine, Boston, MA, USA
| | - J P Simmer
- Department of Biological and Material Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - J D Bartlett
- Department of Mineralized Tissue Biology, The Forsyth Institute, Cambridge, MA, USA, and Harvard School of Dental Medicine, Boston, MA, USA
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16
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Abstract
Human enamel development of the permanent teeth takes place during childhood and stresses encountered during this period can have lasting effects on the appearance and structural integrity of the enamel. One of the most common examples of this is the development of dental fluorosis after childhood exposure to excess fluoride, an elemental agent used to increase enamel hardness and prevent dental caries. Currently the molecular mechanism responsible for dental fluorosis remains unknown; however, recent work suggests dental fluorosis may be the result of activated stress response pathways in ameloblasts during the development of permanent teeth. Using fluorosis as an example, the role of stress response pathways during enamel maturation is discussed.
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Shin M, Hu Y, Tye CE, Guan X, Deagle CC, Antone JV, Smith CE, Simmer JP, Bartlett JD. Matrix metalloproteinase-20 over-expression is detrimental to enamel development: a Mus musculus model. PLoS One 2014; 9:e86774. [PMID: 24466234 PMCID: PMC3900650 DOI: 10.1371/journal.pone.0086774] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 12/17/2013] [Indexed: 12/25/2022] Open
Abstract
Background Matrix metalloproteinase-20 (Mmp20) ablated mice have enamel that is thin and soft with an abnormal rod pattern that abrades from the underlying dentin. We asked if introduction of transgenes expressing Mmp20 would revert this Mmp20 null phenotype back to normal. Unexpectedly, for transgenes expressing medium or high levels of Mmp20, we found opposite enamel phenotypes depending on the genetic background (Mmp20−/− or Mmp20+/+) in which the transgenes were expressed. Methodology/Principal Findings Amelx-promoter-Mmp20 transgenic founder mouse lines were assessed for transgene expression and those expressing low, medium or high levels of Mmp20 were selected for breeding into the Mmp20 null background. Regardless of expression level, each transgene brought the null enamel back to full thickness. However, the high and medium expressing Mmp20 transgenes in the Mmp20 null background had significantly harder more mineralized enamel than did the low transgene expresser. Strikingly, when the high and medium expressing Mmp20 transgenes were present in the wild-type background, the enamel was significantly less well mineralized than normal. Protein gel analysis of enamel matrix proteins from the high and medium expressing transgenes present in the wild-type background demonstrated that greater than normal amounts of cleavage products and smaller quantities of higher molecular weight proteins were present within their enamel matrices. Conclusions/Significance Mmp20 expression levels must be within a specific range for normal enamel development to occur. Creation of a normally thick enamel layer may occur over a wider range of Mmp20 expression levels, but acquisition of normal enamel hardness has a narrower range. Since over-expression of Mmp20 results in decreased enamel hardness, this suggests that a balance exists between cleaved and full-length enamel matrix proteins that are essential for formation of a properly hardened enamel layer. It also suggests that few feedback controls are present in the enamel matrix to prevent excessive MMP20 activity.
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Affiliation(s)
- Masashi Shin
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, United States of America
| | - Coralee E. Tye
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
| | - Xiaomu Guan
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
| | - Craig C. Deagle
- Program in Endodontics, Harvard School of Dental Medicine, Boston Massachusetts, United States of America
| | - Jerry V. Antone
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
| | - Charles E. Smith
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, United States of America
- Facility for Electron Microscopy Research, Department of Anatomy & Cell Biology, and Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - James P. Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, United States of America
| | - John D. Bartlett
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
- * E-mail:
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18
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Sahlberg C, Pavlic A, Ess A, Lukinmaa PL, Salmela E, Alaluusua S. Combined effect of amoxicillin and sodium fluoride on the structure of developing mouse enamel in vitro. Arch Oral Biol 2013; 58:1155-64. [DOI: 10.1016/j.archoralbio.2013.03.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 12/19/2012] [Accepted: 03/12/2013] [Indexed: 10/26/2022]
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19
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Xue H, Li Y, Everett ET, Ryan K, Peng L, Porecha R, Yan Y, Lucchese AM, Kuehl MA, Pugach MK, Bouchard J, Gibson CW. Ameloblasts require active RhoA to generate normal dental enamel. Eur J Oral Sci 2013; 121:293-302. [PMID: 23841780 DOI: 10.1111/eos.12059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2013] [Indexed: 12/20/2022]
Abstract
RhoA plays a fundamental role in regulation of the actin cytoskeleton, intercellular attachment, and cell proliferation. During amelogenesis, ameloblasts (which produce the enamel proteins) undergo dramatic cytoskeletal changes and the RhoA protein level is up-regulated. Transgenic mice were generated that express a dominant-negative RhoA transgene in ameloblasts using amelogenin gene-regulatory sequences. Transgenic and wild-type (WT) molar tooth germs were incubated with sodium fluoride (NaF) or sodium chloride (NaCl) in organ culture. Filamentous actin (F-actin) stained with phalloidin was elevated significantly in WT ameloblasts treated with NaF compared with WT ameloblasts treated with NaCl or with transgenic ameloblasts treated with NaF, thereby confirming a block in the RhoA/Rho-associated protein kinase (ROCK) pathway in the transgenic mice. Little difference in quantitative fluorescence (an estimation of fluorosis) was observed between WT and transgenic incisors from mice provided with drinking water containing NaF. We subsequently found reduced transgene expression in incisors compared with molars. Transgenic molar teeth had reduced amelogenin, E-cadherin, and Ki67 compared with WT molar teeth. Hypoplastic enamel in transgenic mice correlates with reduced expression of the enamel protein, amelogenin, and E-cadherin and cell proliferation are regulated by RhoA in other tissues. Together these findings reveal deficits in molar ameloblast function when RhoA activity is inhibited.
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Affiliation(s)
- Hui Xue
- Department of Anatomy and Cell Biology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA 19104, USA
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DenBesten PK, Zhu L, Li W, Tanimoto K, Liu H, Witkowska HE. Fluoride incorporation into apatite crystals delays amelogenin hydrolysis. Eur J Oral Sci 2012; 119 Suppl 1:3-7. [PMID: 22243219 DOI: 10.1111/j.1600-0722.2011.00903.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enamel fluorosis has been related to an increase in the amount of amelogenin in fluorosed enamel compared with normal enamel in the maturation stage. In this study we tested the hypothesis that fluoride incorporated into carbonated apatite alters amelogenin hydrolysis. Recombinant human amelogenin (rh174) was allowed to bind to 0.15 mg of carbonated hydroxyapatite (CAP) or to fluoride-containing carbonated hydroxyapatite (F-CAP) synthesized to contain 100, 1,000, or 4,000 ppm F(-). After 3 h of digestion with recombinant human matrix metalloproteinase 20 (MMP20) or kallikrein-related peptidase 4 (KLK4), bound protein was characterized by reverse-phase high-performance liquid chromatography (HPLC). Proteolytic fragments of amelogenin formed after 24h of digestion with MMP20 of KLK 4 were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The hydrolysis, by both MMP20 and KLK4, of amelogenin bound to F100-CAP was significantly reduced in a dose-dependent manner compared with the hydrolysis of amelogenin bound to CAP. After 24 h of hydrolysis, a similar number of MMP20 cleavage sites was found for amelogenin bound to CAP and amelogenin bound to F100-CAP; however, 24 fewer KLK4 cleavage sites were identified for amelogenin bound to F100-CAP than for amelogenin bound to CAP. These results suggest that the reduced hydrolysis of amelogenins in fluorosed enamel may be partially caused by the increased fluoride content in fluoride-containing apatite, contributing to the hypomineralized enamel matrix phenotype observed in fluorosed enamel.
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Affiliation(s)
- Pamela K DenBesten
- Department of Orofacial Sciences, School of Dentistry, University of California, San Francisco, CA 94143-0422, USA.
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