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Ji M, Xiao L, Xu L, Huang S, Zhang D. How pH is regulated during amelogenesis in dental fluorosis. Exp Ther Med 2018; 16:3759-3765. [PMID: 30402142 DOI: 10.3892/etm.2018.6728] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 12/01/2017] [Indexed: 12/14/2022] Open
Abstract
Amelogenesis is a complicated process that concerns the interaction between growing hydroxyapatite crystals and extracellular proteins, which requires the tight regulation of pH. In dental fluorosis, the balance of pH regulation is broken, leading to abnormal mineralization. The current review focuses on the electrolyte transport processes associated with pH homeostasis, particularly regarding the changes in ion transporters that occur during amelogenesis, following exposure to excessive fluoride. Furthermore, the possible mechanism of fluorosis is discussed on the basis of acid hypothesis. There are two main methods by which F- accelerates crystal formation in ameloblasts. Firstly, it induces the release of protons, lowering the pH of the cell microenvironment. The decreased pH stimulates the upregulation of ion transporters, which attenuates further declines in the pH. Secondly, F- triggers an unknown signaling pathway, causing changes in the transcription of ion transporters and upregulating the expression of bicarbonate transporters. This results in the release of a large amount of bicarbonate from ameloblasts, which may neutralize the pH to form a microenvironment that favors crystal nucleation. The decreased pH stimulates the diffusion of F- into the cytoplasm of amelobalsts along the concentration gradient formed by the release of protons. The retention of F- causes a series of pathological changes, including oxidative and endoplasmic reticulum stress. If the buffering capacity of ameloblasts facing F- toxicity holds, normal mineralization occurs; however, if F- levels are high enough to overwhelm the buffering capacity of ameloblasts, abnormal mineralization occurs, leading to dental fluorosis.
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Affiliation(s)
- Mei Ji
- Department of Stomatology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China
| | - Lili Xiao
- Department of Stomatology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China
| | - Le Xu
- Department of Stomatology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China
| | - Shengyun Huang
- Department of Stomatology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China
| | - Dongsheng Zhang
- Department of Stomatology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China
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Koruyucu M, Kang J, Kim Y, Seymen F, Kasimoglu Y, Lee Z, Shin T, Hyun H, Kim Y, Lee S, Hu J, Simmer J, Kim J. Hypoplastic AI with Highly Variable Expressivity Caused by ENAM Mutations. J Dent Res 2018; 97:1064-1069. [PMID: 29554435 PMCID: PMC6055254 DOI: 10.1177/0022034518763152] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Tooth enamel, the hardest tissue in the human body, is formed after a complex series of interactions between dental epithelial tissue and the underlying ectomesenchyme. Nonsyndromic amelogenesis imperfecta (AI) is a rare genetic disorder affecting tooth enamel without other nonoral symptoms. In this study, we identified 2 novel ENAM mutations in 2 families with hypoplastic AI by whole exome sequencing. Family 1 had a heterozygous splicing donor site mutation in intron 4, NM_031889; c.123+2T>G. Affected individuals had hypoplastic enamel with or without the characteristic horizontal hypoplastic grooves in some teeth. Family 2 had a nonsense mutation in the last exon, c.1842C>G, p.(Tyr614*), that was predicted to truncate the protein by 500 amino acids. Participating individuals had at least 1 mutant allele, while the proband had a homozygous mutation. Most interestingly, the clinical phenotype of the individuals harboring the heterozygous mutation varied from a lack of penetrance to a mild hypoplastic enamel defect. We believe that these findings will broaden our understanding of the clinical phenotype of AI caused by ENAM mutations.
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Affiliation(s)
- M. Koruyucu
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
| | - J. Kang
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Y.J. Kim
- Department of Molecular Genetics and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - F. Seymen
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
| | - Y. Kasimoglu
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
| | - Z.H. Lee
- Department of Cell and Developmental Biology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - T.J. Shin
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - H.K. Hyun
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Y.J. Kim
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - S.H. Lee
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - J.C.C. Hu
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - J.P. Simmer
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - J.W. Kim
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
- Department of Molecular Genetics and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
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Jiang N, Chen L, Ma Q, Ruan J. Nanostructured Ti surfaces and retinoic acid/dexamethasone present a spatial framework for the maturation and amelogenesis of LS-8 cells. Int J Nanomedicine 2018; 13:3949-3964. [PMID: 30022819 PMCID: PMC6042561 DOI: 10.2147/ijn.s167629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To investigate the amelogenesis-inductive effects of surface structures at the nanoscale. For this purpose, variable nanostructured titanium dioxide (TiO2) surfaces were used as a framework to regulate the amelogenic behaviors of ameloblasts with the administration of retinoic acid (RA)/dexamethasone (DEX). MATERIALS AND METHODS TiO2 nanotubular (NT) surfaces were fabricated via anodization. Mouse ameloblast-like LS-8 cells were seeded and cultured on NT surfaces in the presence or absence of RA/DEX for 48 h. The amelogenic behaviors and extracellular matrix (ECM) mineralization of LS-8 cells on nanostructured Ti surfaces were characterized using field emission scanning electron microscope, laser scanning confocal microscope, quantitative polymerase chain reaction, MTT assay, and flow cytometry. RESULTS TiO2 NT surfaces (tube size ~30 and ~80 nm) were constructed via anodization at 5 or 20 V and denoted as NT5 and NT20, respectively. LS-8 cells exhibited significantly increased spread and proliferation, and lower rates of apoptosis and necrosis on NT surfaces. The amelogenic gene expression and ECM mineralization differed significantly on the NT20 and the NT5 and polished Ti sample surfaces in standard medium. The amelogenic behaviors of LS-8 cells were further changed by RA/DEX pretreatment, which directly drove maturation of LS-8 cells. CONCLUSION Controlling the amelogenic behaviors of ameloblast-like LS-8 cells by manipulating the nanostructure of biomaterials surfaces represents an effective tool for the establishment of a systemic framework for supporting enamel regeneration. The administration of RA/DEX is an effective approach for driving the amelogenesis and maturation of ameloblasts.
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Affiliation(s)
- Nan Jiang
- Department of Preventive Dentistry, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
- Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
| | - Lu Chen
- Department of Preventive Dentistry, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
- Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
| | - Qianli Ma
- Department of Immunology, School of Basic Medicine, Fourth Military Medical University, Xi'an, People's Republic of China,
- Department of Prosthodontics, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
| | - Jianping Ruan
- Department of Preventive Dentistry, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
- Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, College of Stomatology, Xi'an JiaoTong University, Xi'an, People's Republic of China,
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Chu Q, Gao Y, Gao X, Dong Z, Song W, Xu Z, Xiang L, Wang Y, Zhang L, Li M, Gao Y. Ablation of Runx2 in Ameloblasts Suppresses Enamel Maturation in Tooth Development. Sci Rep 2018; 8:9594. [PMID: 29941908 PMCID: PMC6018461 DOI: 10.1038/s41598-018-27873-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 06/11/2018] [Indexed: 11/21/2022] Open
Abstract
Runt-related transcription factor 2 (Runx2) is involved in the early stage of tooth development. However, only few studies have reported the role of Runx2 in enamel development, which may be attributed to that Runx2 full knockout mice cannot survive after birth. In the present study, we successfully established a Runx2-deficient mouse model using a conditional knockout (cKO) method. We observed a significant reduction in the degree of mineralization and the decreased size of enamel rods in cKO mice. Histological analysis showed the retained enamel proteins in enamel layer at maturation stage in cKO molars. Further analysis by qRT-PCR revealed that the expressions of genes encoding enamel structure proteins, such as amelogenin (AMELX), ameloblastin (AMBN) and enamelin (ENAM), were increased in cKO enamel organs. On the other hand, the expression of kallikrein-related peptidase-4 (KLK4) at the mRNA and protein levels was dramatically decreased from late secretory stage to maturation stage in cKO enamel organs, while the expression of matrix metalloproteinase-20 (MMP-20) was not significantly altered. Finally, immunohistochemistry indicated that the uptake of amelogenins by ameloblasts was significantly decreased in cKO mice. Taken together, Runx2 played critical roles in controlling enamel maturation by increasing synthesis of KLK4 and decreasing synthesis of AMELX, AMBN and ENAM.
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Affiliation(s)
- Qing Chu
- Department of Pediatrics and Preventive Dentistry, Hospital Affiliated to Binzhou Medical University, Binzhou, 256600, Shandong, China
| | - Yan Gao
- Department of Pediatrics and Preventive Dentistry, Hospital Affiliated to Binzhou Medical University, Binzhou, 256600, Shandong, China
| | - Xianhua Gao
- Department of Pediatrics and Preventive Dentistry, Hospital Affiliated to Binzhou Medical University, Binzhou, 256600, Shandong, China
| | - Zhiheng Dong
- Department of Pediatrics and Preventive Dentistry, Hospital Affiliated to Binzhou Medical University, Binzhou, 256600, Shandong, China
| | - Wenying Song
- Department of Pediatrics and Preventive Dentistry, Hospital Affiliated to Binzhou Medical University, Binzhou, 256600, Shandong, China
| | - Zhenzhen Xu
- Department of Pediatrics and Preventive Dentistry, Hospital Affiliated to Binzhou Medical University, Binzhou, 256600, Shandong, China
| | - Lili Xiang
- Department of Pediatrics and Preventive Dentistry, Hospital Affiliated to Binzhou Medical University, Binzhou, 256600, Shandong, China
| | - Yumin Wang
- Institute of Stomatology, Binzhou Medical University, Yantai, 255000, Shandong, China
| | - Li Zhang
- Institute of Stomatology, Binzhou Medical University, Yantai, 255000, Shandong, China
| | - Mingyu Li
- Shanghai Key Laboratory of Stomatology, Shanghai Research Institute of Stomatology, Ninth People's Hospital, Faculty of Medicine, Shanghai Jiao Tong University, Shanghai, 200011, China
| | - Yuguang Gao
- Department of Pediatrics and Preventive Dentistry, Hospital Affiliated to Binzhou Medical University, Binzhou, 256600, Shandong, China.
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55
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Li J, Zhao L, Zhao X, Wang P, Liu Y, Ruan J. Foxo1 Attenuates NaF-Induced Apoptosis of LS8 Cells through the JNK and Mitochondrial Pathways. Biol Trace Elem Res 2018; 181:104-111. [PMID: 28429284 DOI: 10.1007/s12011-017-1015-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 04/04/2017] [Indexed: 12/21/2022]
Abstract
Fluoride-induced ameloblast apoptosis is a key event in dental fluorosis development. Forkhead box o1 (Foxo1) is a transcription factor involved in cell apoptosis. The present study aims to investigate the effect of Foxo1 on ameloblast apoptosis induced by fluoride in vitro and to explore its possible mechanism. Ameloblast-like cells (LS8 cells) were exposed to various concentrations of NaF for up to 48 h. Foxo1 activation was modulated using lentiviral vectors, and cell apoptosis was measured by flow cytometry. The expression levels of Foxo1, c-Jun N-terminal kinase (JNK), and some well-known regulators of the mitochondrial pathway of apoptosis (cytoplasmic cytochrome c, cleaved caspase-9, cleaved caspase-3, Bcl-2, and Bax) were detected by quantitative real-time PCR, western blot, and immunofluorescence assay. The results showed significantly decreased expression and increased phosphorylation of Foxo1 in NaF-treated LS8 cells. Further investigation revealed that forced Foxo1 activation with lentiviral vectors attenuated NaF-induced apoptosis of LS8 cells, markedly decreasing protein levels of cytoplasmic cytochrome c, cleaved caspase-9, and cleaved caspase-3 while increasing the Bcl-2/Bax ratio and JNK expression level. These findings suggest that Foxo1 attenuated NaF-induced apoptosis of LS8 cells via inhibiting the mitochondrial pathway and activating JNK.
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Affiliation(s)
- Juedan Li
- Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, Shaanxi, 710004, People's Republic of China
| | - Lin Zhao
- Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, Shaanxi, 710004, People's Republic of China
- Department of Oral Pathology, College of Stomatology, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750021, People's Republic of China
| | - Xiaomeng Zhao
- Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, Shaanxi, 710004, People's Republic of China
| | - Peng Wang
- Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, Shaanxi, 710004, People's Republic of China
| | - Yan Liu
- Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, Shaanxi, 710004, People's Republic of China
| | - Jianping Ruan
- Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, Shaanxi, 710004, People's Republic of China.
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56
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Ogata K, Tsumuraya T, Oka K, Shin M, Okamoto F, Kajiya H, Katagiri C, Ozaki M, Matsushita M, Okabe K. The crucial role of the TRPM7 kinase domain in the early stage of amelogenesis. Sci Rep 2017; 7:18099. [PMID: 29273814 PMCID: PMC5741708 DOI: 10.1038/s41598-017-18291-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 12/07/2017] [Indexed: 12/15/2022] Open
Abstract
Transient receptor potential melastatin-7 (TRPM7) is a bi-functional protein containing a kinase domain fused to an ion channel. TRPM7 is highly expressed in ameloblasts during tooth development. Here we show that TRPM7 kinase-inactive knock-in mutant mice (TRPM7 KR mice) exhibited small enamel volume with opaque white-colored incisors. The TRPM7 channel function of ameloblast-lineage cells from TRPM7 KR mice was normal. Interestingly, phosphorylation of intracellular molecules including Smad1/5/9, p38 and cAMP response element binding protein (CREB) was inhibited in ameloblasts from TRPM7 KR mice at the pre-secretory stage. An immunoprecipitation assay showed that CREB was bound to TRPM7, suggesting that direct phosphorylation of CREB by TRPM7 was inhibited in ameloblast-lineage cells from TRPM7 KR mice. These results indicate that the function of the TRPM7 kinase domain plays an important role in ameloblast differentiation, independent of TRPM7 channel activity, via phosphorylation of CREB.
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Affiliation(s)
- Kayoko Ogata
- Section of Cellular Physiology, Department of Physiological Sciences and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan.,Section of Pediatric Dentistry, Department of Oral Growth and Development, Fukuoka Dental College, Fukuoka, Japan
| | - Tomoyuki Tsumuraya
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Kyoko Oka
- Section of Pediatric Dentistry, Department of Oral Growth and Development, Fukuoka Dental College, Fukuoka, Japan.
| | - Masashi Shin
- Section of Cellular Physiology, Department of Physiological Sciences and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
| | - Fujio Okamoto
- Section of Cellular Physiology, Department of Physiological Sciences and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
| | - Hiroshi Kajiya
- Section of Cellular Physiology, Department of Physiological Sciences and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
| | - Chiaki Katagiri
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Masao Ozaki
- Section of Pediatric Dentistry, Department of Oral Growth and Development, Fukuoka Dental College, Fukuoka, Japan
| | - Masayuki Matsushita
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Koji Okabe
- Section of Cellular Physiology, Department of Physiological Sciences and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
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57
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Yan WJ, Ma P, Tian Y, Wang JY, Qin CL, Feng JQ, Wang XF. The importance of a potential phosphorylation site in enamelin on enamel formation. Int J Oral Sci 2017; 9:e4. [PMID: 29593332 PMCID: PMC5775333 DOI: 10.1038/ijos.2017.41] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2017] [Indexed: 01/31/2023] Open
Abstract
Enamelin (ENAM) has three putative phosphoserines (pSers) phosphorylated by a Golgi-associated secretory pathway kinase (FAM20C) based on their distinctive Ser-x-Glu (S-x-E) motifs. Fam20C-knockout mice show severe enamel defects similar to those in the Enam-knockout mice, implying an important role of the pSers in ENAM. To determine the role of pSer55 in ENAM, we characterized ENAMRgsc514 mice, in which Ser55 cannot be phosphorylated by FAM20C due to an E57>G57 mutation in the S-x-E motif. The enamel microstructure of 4-week-old mice was examined by scanning electron microscopy. The teeth of 6-day-old mice were characterized by histology and immunohistochemistry. The protein lysates of the first lower molars of 4-day-old mice were analyzed by Western immunoblotting using antibodies against ENAM, ameloblastin and amelogenin. ENAMRgsc514 heterozygotes showed a disorganized enamel microstructure, while the homozygotes had no enamel on the dentin surface. The N-terminal fragments of ENAM in the heterozygotes were detained in the ameloblasts and localized in the mineralization front of enamel matrix, while those in the WT mice were secreted out of ameloblasts and distributed evenly in the outer 1/2 of enamel matrix. Surprisingly, the ~15 kDa C-terminal fragments of ameloblastin were not detected in the molar lysates of the homozygotes. These results suggest that the phosphorylation of Ser55 may be an essential posttranslational modification of ENAM and is required for the interaction with other enamel matrix molecules such as ameloblastin in mediating the structural organization of enamel matrix and protein-mineral interactions during enamel formation.International Journal of Oral Science (2017) 9;e4; doi:10.1038/ijos.2017.41; published online 29 November 2017.
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Affiliation(s)
- Wen-Juan Yan
- Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University College of Dentistry, Dallas, USA.,Department of Endodontics, Nanfan Hospital, Southern Medical University, Guangzhou, China
| | - Pan Ma
- Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University College of Dentistry, Dallas, USA
| | - Ye Tian
- Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University College of Dentistry, Dallas, USA
| | - Jing-Ya Wang
- Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University College of Dentistry, Dallas, USA
| | - Chun-Lin Qin
- Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University College of Dentistry, Dallas, USA
| | - Jian Q Feng
- Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University College of Dentistry, Dallas, USA
| | - Xiao-Fang Wang
- Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University College of Dentistry, Dallas, USA
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Brookes SJ, Barron MJ, Smith CEL, Poulter JA, Mighell AJ, Inglehearn CF, Brown CJ, Rodd H, Kirkham J, Dixon MJ. Amelogenesis imperfecta caused by N-terminal enamelin point mutations in mice and men is driven by endoplasmic reticulum stress. Hum Mol Genet 2017; 26:1863-1876. [PMID: 28334996 PMCID: PMC5411757 DOI: 10.1093/hmg/ddx090] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 03/02/2017] [Indexed: 12/30/2022] Open
Abstract
‘Amelogenesis imperfecta’ (AI) describes a group of inherited diseases of dental enamel that have major clinical impact. Here, we identify the aetiology driving AI in mice carrying a p.S55I mutation in enamelin; one of the most commonly mutated proteins underlying AI in humans. Our data indicate that the mutation inhibits the ameloblast secretory pathway leading to ER stress and an activated unfolded protein response (UPR). Initially, with the support of the UPR acting in pro-survival mode, Enamp.S55I heterozygous mice secreted structurally normal enamel. However, enamel secreted thereafter was structurally abnormal; presumably due to the UPR modulating ameloblast behaviour and function in an attempt to relieve ER stress. Homozygous mutant mice failed to produce enamel. We also identified a novel heterozygous ENAMp.L31R mutation causing AI in humans. We hypothesize that ER stress is the aetiological factor in this case of human AI as it shared the characteristic phenotype described above for the Enamp.S55I mouse. We previously demonstrated that AI in mice carrying the Amelxp.Y64H mutation is a proteinopathy. The current data indicate that AI in Enamp.S55I mice is also a proteinopathy, and based on comparative phenotypic analysis, we suggest that human AI resulting from the ENAMp.L31R mutation is another proteinopathic disease. Identifying a common aetiology for AI resulting from mutations in two different genes opens the way for developing pharmaceutical interventions designed to relieve ER stress or modulate the UPR during enamel development to ameliorate the clinical phenotype.
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Affiliation(s)
- Steven J Brookes
- Department of Oral Biology, School of Dentistry, Wellcome Trust Brenner Building University Of Leeds, St James's University Hospital, Leeds LS9 7TF, UK
| | - Martin J Barron
- Faculty of Biology, Medicine & Health, Manchester Academic Health Sciences Centre, University of Manchester, Michael Smith Building, Manchester M13 9PT, UK
| | - Claire E L Smith
- Department of Oral Medicine, School of Dentistry, University of Leeds, Leeds, UK
| | - James A Poulter
- Department of Oral Medicine, School of Dentistry, University of Leeds, Leeds, UK
| | - Alan J Mighell
- Leeds Institute of Biomedical and Clinical Sciences, St James's University Hospital, University of Leeds, Leeds LS9 7TF, UK
| | - Chris F Inglehearn
- Department of Oral Medicine, School of Dentistry, University of Leeds, Leeds, UK
| | - Catriona J Brown
- Birmingham Dental Hospital and School of Dentistry, Birmingham B5 7EG, UK
| | - Helen Rodd
- Unit of Oral Health and Development, School of Clinical Dentistry, University of Sheffield, Sheffield, UK
| | - Jennifer Kirkham
- Department of Oral Biology, School of Dentistry, Wellcome Trust Brenner Building University Of Leeds, St James's University Hospital, Leeds LS9 7TF, UK
| | - Michael J Dixon
- Faculty of Biology, Medicine & Health, Manchester Academic Health Sciences Centre, University of Manchester, Michael Smith Building, Manchester M13 9PT, UK
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59
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Lacruz RS, Habelitz S, Wright JT, Paine ML. DENTAL ENAMEL FORMATION AND IMPLICATIONS FOR ORAL HEALTH AND DISEASE. Physiol Rev 2017; 97:939-993. [PMID: 28468833 DOI: 10.1152/physrev.00030.2016] [Citation(s) in RCA: 223] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/10/2017] [Accepted: 01/10/2017] [Indexed: 12/16/2022] Open
Abstract
Dental enamel is the hardest and most mineralized tissue in extinct and extant vertebrate species and provides maximum durability that allows teeth to function as weapons and/or tools as well as for food processing. Enamel development and mineralization is an intricate process tightly regulated by cells of the enamel organ called ameloblasts. These heavily polarized cells form a monolayer around the developing enamel tissue and move as a single forming front in specified directions as they lay down a proteinaceous matrix that serves as a template for crystal growth. Ameloblasts maintain intercellular connections creating a semi-permeable barrier that at one end (basal/proximal) receives nutrients and ions from blood vessels, and at the opposite end (secretory/apical/distal) forms extracellular crystals within specified pH conditions. In this unique environment, ameloblasts orchestrate crystal growth via multiple cellular activities including modulating the transport of minerals and ions, pH regulation, proteolysis, and endocytosis. In many vertebrates, the bulk of the enamel tissue volume is first formed and subsequently mineralized by these same cells as they retransform their morphology and function. Cell death by apoptosis and regression are the fates of many ameloblasts following enamel maturation, and what cells remain of the enamel organ are shed during tooth eruption, or are incorporated into the tooth's epithelial attachment to the oral gingiva. In this review, we examine key aspects of dental enamel formation, from its developmental genesis to the ever-increasing wealth of data on the mechanisms mediating ionic transport, as well as the clinical outcomes resulting from abnormal ameloblast function.
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Affiliation(s)
- Rodrigo S Lacruz
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
| | - Stefan Habelitz
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
| | - J Timothy Wright
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
| | - Michael L Paine
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
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60
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Xin W, Wenjun W, Man Q, Yuming Z. Novel FAM83H mutations in patients with amelogenesis imperfecta. Sci Rep 2017; 7:6075. [PMID: 28729668 PMCID: PMC5519741 DOI: 10.1038/s41598-017-05208-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 05/25/2017] [Indexed: 11/09/2022] Open
Abstract
Amelogenesis imperfecta (AI), characterized by a deficiency in the quantity and/or quality of dental enamel, is genetically heterogeneous and phenotypically variable. The most severe type, hypocalcified AI, is mostly caused by truncating mutations in the FAM83H gene. This study aimed to identify genetic mutations in four Chinese families with hypocalcified AI. We performed mutation analysis by sequencing the candidate FAM83H gene. Three novel mutations (c.931dupC, p.V311Rfs*13; c.1130_1131delinsAA, p.S377X; and c.1147 G > T, p.E383X) and one previously reported mutation (c.973 C > T, p.R325X) in the last exon of FAM83H gene were identified. Furthermore, constructs expressing Green fluorescent protein (GFP)-tagged wild-type and three novel mutant FAM83Hs were transfected into rat dental epithelial cells (SF2 cells). Wild-type FAM83H-GFP was localized exclusively in the cytoplasm, especially in the area surrounding the nucleus, while the mutant FAM83H-GFPs (p.V311Rfs*13, p.S377X, and p.E383X) were localized predominantly in the nucleus, with lower levels in the cytoplasm.
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Affiliation(s)
- Wang Xin
- Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, PR China
| | - Wang Wenjun
- Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, PR China.,National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, PR China.,Beijing Key Laboratory of Digital Stomatology, Beijing, PR China
| | - Qin Man
- Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, PR China
| | - Zhao Yuming
- Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, PR China.
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61
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Kim Y, Hur SW, Jeong BC, Oh SH, Hwang YC, Kim SH, Koh JT. The Fam50a positively regulates ameloblast differentiation via interacting with Runx2. J Cell Physiol 2017; 233:1512-1522. [PMID: 28574578 DOI: 10.1002/jcp.26038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 06/01/2017] [Indexed: 11/12/2022]
Abstract
Differentiated ameloblasts secret enamel matrix proteins such as amelogenin, ameloblastin, and enamelin. Expression levels of these proteins are regulated by various factors. To find a new regulatory factor for ameloblast differentiation, we performed 2D-PAGE analysis using mouse ameloblast lineage cell line (mALCs) cultured with mineralizing medium. Of identified proteins, family with sequence similarity 50 member A (Fam50a) was significantly increased during differentiation of mALCs. Fam50a protein was also highly expressed in secretory ameloblasts of mouse tooth germs. In mALCs cultures, forced expression of Fam50a up-regulated the expression of enamel matrix protein genes such as amelogenin, ameloblastin, and enamelin. In addition, up-regulation of Fam50a also increased ALP activity and mineralized nodule formation in a dose-dependent manner. In contrast, knockdown of Fam50a decreased expression levels of enamel matrix protein genes, ALP activity, and mineralized nodule formation. By fluorescence microscopy, endogenous Fam50a protein was found to be localized to the nucleus of ameloblasts. In addition, Fam50a synergistically increased Ambn transactivation by Runx2. Moreover, Fam50a increased binding affinity of Runx2 to Ambn promoter by physically interacting with Runx2. Taken together, these results suggest Fam50a might be a new positive regulator of ameloblast differentiation.
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Affiliation(s)
- Yuri Kim
- Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, South Korea.,Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, South Korea
| | - Sung-Woong Hur
- Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, South Korea.,Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, South Korea
| | - Byung-Chul Jeong
- Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, South Korea.,Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, South Korea
| | - Sin-Hye Oh
- Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, South Korea.,Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, South Korea
| | - Yun-Chan Hwang
- Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, South Korea.,Department of Conservative Dentistry, School of Dentistry, Chonnam National University, Gwangju, South Korea
| | - Sun-Hun Kim
- Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, South Korea.,Department of Oral Anatomy, School of Dentistry, Chonnam National University, Gwangju, South Korea
| | - Jeong-Tae Koh
- Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, South Korea.,Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju, South Korea
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62
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Yachuan Z, Xuedong Z, Liwei Z. [Expression and function of microRNAs in enamel development]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2017; 35:328-333. [PMID: 28675021 DOI: 10.7518/hxkq.2017.03.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
microRNAs (miRNAs) are endogenous short, noncoding RNAs that can negatively regulate gene expression post-transcriptionally. miRNAs are involved in multiple developmental events in various tissues and organs, including dental enamel development. Any disruption during enamel development may result in inherited enamel malformations. This article reviews the expression and function of miRNAs in enamel development.
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Affiliation(s)
- Zhou Yachuan
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Zhou Xuedong
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Zheng Liwei
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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63
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Robertson SYT, Wen X, Yin K, Chen J, Smith CE, Paine ML. Multiple Calcium Export Exchangers and Pumps Are a Prominent Feature of Enamel Organ Cells. Front Physiol 2017; 8:336. [PMID: 28588505 PMCID: PMC5440769 DOI: 10.3389/fphys.2017.00336] [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: 03/13/2017] [Accepted: 05/08/2017] [Indexed: 12/11/2022] Open
Abstract
Calcium export is a key function for the enamel organ during all stages of amelogenesis. Expression of a number of ATPase calcium transporting, plasma membrane genes (ATP2B1-4/PMCA1-4), solute carrier SLC8A genes (sodium/calcium exchanger or NCX1-3), and SLC24A gene family members (sodium/potassium/calcium exchanger or NCKX1-6) have been investigated in the developing enamel organ in earlier studies. This paper reviews the calcium export pathways that have been described and adds novel insights to the spatiotemporal expression patterns of PMCA1, PMCA4, and NCKX3 during amelogenesis. New data are presented to show the mRNA expression profiles for the four Atp2b1-4 gene family members (PMCA1-4) in secretory-stage and maturation-stage rat enamel organs. These data are compared to expression profiles for all Slc8a and Slc24a gene family members. PMCA1, PMCA4, and NCKX3 immunolocalization data is also presented. Gene expression profiles quantitated by real time PCR show that: (1) PMCA1, 3, and 4, and NCKX3 are most highly expressed during secretory-stage amelogenesis; (2) NCX1 and 3, and NCKX6 are expressed during secretory and maturation stages; (3) NCKX4 is most highly expressed during maturation-stage amelogenesis; and (4) expression levels of PMCA2, NCX2, NCKX1, NCKX2, and NCKX5 are negligible throughout amelogenesis. In the enamel organ PMCA1 localizes to the basolateral membrane of both secretory and maturation ameloblasts; PMCA4 expression is seen in the basolateral membrane of secretory and maturation ameloblasts, and also cells of the stratum intermedium and papillary layer; while NCKX3 expression is limited to Tomes' processes, and the apical membrane of maturation-stage ameloblasts. These new findings are discussed in the perspective of data already present in the literature, and highlight the multiplicity of calcium export systems in the enamel organ needed to regulate biomineralization.
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Affiliation(s)
- Sarah Y T Robertson
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern CaliforniaLos Angeles, CA, United States
| | - Xin Wen
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern CaliforniaLos Angeles, CA, United States
| | - Kaifeng Yin
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern CaliforniaLos Angeles, CA, United States
| | - Junjun Chen
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern CaliforniaLos Angeles, CA, United States.,Department of Oral Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of MedicineShanghai, China.,Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of MedicineShanghai, China
| | - Charles E Smith
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill UniversityMontreal, QC, Canada
| | - Michael L Paine
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern CaliforniaLos Angeles, CA, United States
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64
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Duverger O, Ohara T, Bible PW, Zah A, Morasso MI. DLX3-Dependent Regulation of Ion Transporters and Carbonic Anhydrases is Crucial for Enamel Mineralization. J Bone Miner Res 2017; 32:641-653. [PMID: 27760456 PMCID: PMC11025043 DOI: 10.1002/jbmr.3022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/10/2016] [Accepted: 10/14/2016] [Indexed: 12/11/2022]
Abstract
Patients with tricho-dento-osseous (TDO) syndrome, an ectodermal dysplasia caused by mutations in the homeodomain transcription factor DLX3, exhibit enamel hypoplasia and hypomineralization. Here we used a conditional knockout mouse model to investigate the developmental and molecular consequences of Dlx3 deletion in the dental epithelium in vivo. Dlx3 deletion in the dental epithelium resulted in the formation of chalky hypomineralized enamel in all teeth. Interestingly, transcriptomic analysis revealed that major enamel matrix proteins and proteases known to be involved in enamel secretion and maturation were not affected significantly by Dlx3 deletion in the enamel organ. In contrast, expression of several ion transporters and carbonic anhydrases known to play an important role in enamel pH regulation during maturation was significantly affected in enamel organs lacking DLX3. Most of these affected genes showed binding of DLX3 to their proximal promoter as evidenced by chromatin immunoprecipitation sequencing (ChIP-seq) analysis on rat enamel organ. These molecular findings were consistent with altered pH staining evidenced by disruption of characteristic pH oscillations in the enamel. Taken together, these results show that DLX3 is indispensable for the regulation of ion transporters and carbonic anhydrases during the maturation stage of amelogenesis, exerting a crucial regulatory function on pH oscillations during enamel mineralization. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Olivier Duverger
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Takahiro Ohara
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Paul W Bible
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Angela Zah
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Maria I Morasso
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
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65
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Prasad MK, Laouina S, El Alloussi M, Dollfus H, Bloch-Zupan A. Amelogenesis Imperfecta: 1 Family, 2 Phenotypes, and 2 Mutated Genes. J Dent Res 2016; 95:1457-1463. [PMID: 27558265 DOI: 10.1177/0022034516663200] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Amelogenesis imperfecta (AI) is a clinically and genetically heterogeneous group of diseases characterized by enamel defects. The authors have identified a large consanguineous Moroccan family segregating different clinical subtypes of hypoplastic and hypomineralized AI in different individuals within the family. Using targeted next-generation sequencing, the authors identified a novel heterozygous nonsense mutation in COL17A1 (c.1873C>T, p.R625*) segregating with hypoplastic AI and a novel homozygous 8-bp deletion in C4orf26 (c.39_46del, p.Cys14Glyfs*18) segregating with hypomineralized-hypoplastic AI in this family. This study highlights the phenotypic and genotypic heterogeneity of AI that can exist even within a single consanguineous family. Furthermore, the identification of novel mutations in COL17A1 and C4orf26 and their correlation with distinct AI phenotypes can contribute to a better understanding of the pathophysiology of AI and the contribution of these genes to amelogenesis.
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Affiliation(s)
- M K Prasad
- Laboratoire de Génétique Médicale, INSERM U1112, Institut de Génétique Médicale d'Alsace, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, Strasbourg, France
| | - S Laouina
- Department of Pediatric Dentistry, Faculty of Dental Medicine, Mohammed V University, Rabat, Morocco
| | - M El Alloussi
- Department of Pediatric Dentistry, Faculty of Dental Medicine, Mohammed V University, Rabat, Morocco
| | - H Dollfus
- Laboratoire de Génétique Médicale, INSERM U1112, Institut de Génétique Médicale d'Alsace, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, Strasbourg, France
- Centre de Référence pour les Affections Rares en Génétique Ophtalmologique, Service de Génétique Médicale, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - A Bloch-Zupan
- Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France
- Pôle de Médecine et Chirurgie Bucco-Dentaires, Centre de Référence des Manifestations Odontologiques des Maladies Rares, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
- Institut de Génétique et de Biologie Moléculaire and Cellulaire, CNRS UMR7104, INSERM U964, Centre Européen de Recherche en Biologie et en Médecine, Université de Strasbourg, Illkirch, France
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66
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Atalayin C, Tezel H, Dagci T, Karabay Yavasoglu NU, Oktem G, Kose T. In vivo performance of different scaffolds for dental pulp stem cells induced for odontogenic differentiation. Braz Oral Res 2016; 30:e120. [PMID: 27901202 DOI: 10.1590/1807-3107bor-2016.vol30.0120] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/16/2016] [Indexed: 12/30/2022] Open
Abstract
This study was designed to determine the in vivo performance of three different materials as scaffolds for dental pulp stem cells (DPSC) undergoing induced odontogenic differentiation. An odontogenic medium modified by the addition of recombinant human bone morphogenetic protein 2 was used in the experimental groups to induce differentiation. Mesenchymal stem cell medium was used in the control groups. DPSC were transplanted onto the backs of mice via three scaffolds: copolymer of L-lactide and DL-lactide (PLDL), copolymer of DL-lactide (PDL) and hydroxyapatite tricalcium phosphate (HA/TCP). The expression levels of dentin sialo-phosphoprotein (DSPP), dentin matrix protein-1 (DMP1), enamelysin/matrix metalloproteinase 20 (MMP20) and phosphate-regulating gene with homologies to endopeptidases on X chromosome (PHEX) were analysed using RT-PCR. The expressions in the experimental groups were compared to those in the control groups. The transcript expressions at 6 and 12 weeks were significantly different for all scaffolds (p < 0.05), except for the expression of DSPP in the PLDL group with regard to the time variable. Although there was a decrease in the expression of enamelysin/MMP20 in PLDL and HA/TCP at 12 weeks, all other expressions increased and reached their highest level at 12 weeks. The highest DSPP expression was in the PDL group (p < 0.05). The highest expression of DMP1 was detected in the HA/TCP group (p < 0.05). The highest expression of PHEX was in the PLDL group (p < 0.05). Consequently, PLDL and PDL seemed to be promising scaffold candidates for odontogenic regeneration at least as HA-TCP, when they were applied with the DPSC induced for odontogenic differentiation.
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Affiliation(s)
- Cigdem Atalayin
- Ege University, School of Dentistry, Department of Restorative Dentistry, Izmir, Turkey
| | - Huseyin Tezel
- Ege University, School of Dentistry, Department of Restorative Dentistry, Izmir, Turkey
| | - Taner Dagci
- Ege University, School of Medicine, Department of Physiology, Izmir, Turkey
| | | | - Gulperi Oktem
- Ege University, School of Medicine, Department of Histology and Embryology, Izmir, Turkey
| | - Timur Kose
- Ege University, School of Medicine, Department of Biostatistics and Medical Informatics, Izmir, Turkey
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67
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Gostyńska KB, Yan Yuen W, Pasmooij AMG, Stellingsma C, Pas HH, Lemmink H, Jonkman MF. Carriers with functional null mutations in LAMA3 have localized enamel abnormalities due to haploinsufficiency. Eur J Hum Genet 2016; 25:94-99. [PMID: 27827380 DOI: 10.1038/ejhg.2016.136] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 08/10/2016] [Accepted: 09/06/2016] [Indexed: 11/09/2022] Open
Abstract
The hereditary blistering disease junctional epidermolysis bullosa (JEB) is always accompanied by structural enamel abnormalities of primary and secondary dentition, characterized as amelogenesis imperfecta. Autosomal recessive mutations in LAMA3, LAMB3 and LAMC2 encoding the heterotrimer laminin 332 (LM-332) are among the genes causing JEB. While examining pedigrees of JEB patients with LAMA3 mutations, we observed that heterozygous carriers of functional null mutations displayed subtle enamel pitting in the absence of skin fragility or other JEB symptoms. Here, we report two new LAMA3 functional null mutations: nonsense c.2377C>T p.(Arg793Ter) and splice-site c.4684+1G>A mutation in heterozygous carriers exhibiting enamel pitting. Both parents had offspring affected with JEB and displayed subtle enamel pitting of secondary dentition without any sign of skin blistering. The reported enamel abnormality in LAMA3 mutation carriers could be attributed to a half dose effect of the laminin α3 chain (haploinsufficiency).
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Affiliation(s)
- Katarzyna B Gostyńska
- Departments of Dermatology, Center for Blistering Diseases, Groningen, The Netherlands.
| | - Wing Yan Yuen
- Departments of Dermatology, Center for Blistering Diseases, Groningen, The Netherlands
| | | | - Cornelius Stellingsma
- Oral and Maxillofacial Surgery and Maxillofacial Prosthetics Genetics, Groningen, The Netherlands
| | - Hendri H Pas
- Departments of Dermatology, Center for Blistering Diseases, Groningen, The Netherlands
| | - Henny Lemmink
- University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Marcel F Jonkman
- Departments of Dermatology, Center for Blistering Diseases, Groningen, The Netherlands
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68
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de Deus Moura de Lima M, Sousa HCS, de F Tima Almeida de Deus Moura L. Letter To The Editor. Oper Dent 2016; 41:672-674. [PMID: 27820686 DOI: 10.2341/1559-2863-41.6.672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Marina de Deus Moura de Lima
- Department of Pathology and Dentistry Clinic, School od Dentistry, Universidade Federal do Piauí - UFPI, Teresina, Brazil
| | - Heloísa Clara Santos Sousa
- Department of Pathology and Dentistry Clinic, School od Dentistry, Universidade Federal do Piauí - UFPI, Teresina, Brazil
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69
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Kwak SY, Yamakoshi Y, Simmer JP, Margolis HC. MMP20 Proteolysis of Native Amelogenin Regulates Mineralization In Vitro. J Dent Res 2016; 95:1511-1517. [PMID: 27558264 DOI: 10.1177/0022034516662814] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Recent studies have shown that native phosphorylated full-length porcine amelogenin (P173) and its predominant cleavage product (P148) can inhibit spontaneous calcium phosphate formation in vitro by stabilizing an amorphous calcium phosphate (ACP) precursor phase. Since full-length amelogenin undergoes proteolysis by matrix metalloproteinase 20 (MMP20, enamelysin) soon after secretion, the present study was conducted to assess the effect of amelogenin proteolysis on calcium phosphate formation. Calcium and phosphate were sequentially added to protein solutions without and with added MMP20 (ratio = 200:1) under physiological-like conditions of ionic strength (163 mM) in 50 mM Tris-HCl (pH 7.4) at 37 °C. Protein degradation with time was assessed by gel-electrophoresis, and mineral products formed were characterized by transmission electron microscopy (TEM). MMP20 was found to cleave P173 to primarily generate P148, along with P162, P46-148, and P63/64-148. In sharp contrast, MMP20 did not cleave P148. In addition, the formation of well-aligned bundles of enamel-like hydroxyapatite (HA) crystals was promoted in the presence of P173 with added MMP20, while only ACP particles were seen in the absence of MMP20. Although P148 was found to have a somewhat lower capacity to stabilize ACP and prevent HA formation compared with P173 in the absence of MMP20, essentially no HA formation was observed in the presence of somewhat higher concentrations of P148 regardless of MMP20 addition, due to the lack of observed protein proteolysis. Present findings suggest that ACP transformation to ordered arrays of enamel crystals may be regulated in part by the proteolysis of full-length native amelogenin, while the predominant amelogenin degradation product in developing enamel (e.g., P148) primarily serves to prevent uncontrolled mineral formation during the secretory stage of amelogenesis.
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Affiliation(s)
- S Y Kwak
- Center for Biomineralization, Department of Applied Oral Sciences, The Forsyth Institute, Cambridge, MA, USA.,Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
| | - Y Yamakoshi
- Department of Biochemistry and Molecular Biology, School of Dental Medicine, Tsurumi University, Yokohama, Japan
| | - J P Simmer
- Department of Biologic and Materials Science, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - H C Margolis
- Center for Biomineralization, Department of Applied Oral Sciences, The Forsyth Institute, Cambridge, MA, USA .,Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
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70
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Amelogenesis imperfecta: review of diagnostic findings and treatment concepts. Odontology 2016; 104:245-56. [DOI: 10.1007/s10266-016-0266-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 07/25/2016] [Indexed: 10/21/2022]
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71
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Kim YJ, Shin TJ, Hyun HK, Lee SH, Lee ZH, Kim JW. A novel de novo mutation in LAMB3 causes localized hypoplastic enamel in the molar region. Eur J Oral Sci 2016; 124:403-5. [PMID: 27220909 DOI: 10.1111/eos.12280] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2016] [Indexed: 11/29/2022]
Abstract
Amelogenesis imperfecta (AI) is a collection of diseases characterized by hereditary enamel defects and is heterogeneous in genetic etiology and clinical phenotype. In this study, we recruited a nuclear AI family with a proband having unique irregular hypoplastic pits and grooves in all surfaces of the deciduous molar teeth but not in the deciduous anterior teeth. Based on the candidate gene approach, we screened the laminin subunit beta 3 (LAMB3) gene and identified a novel de novo mutation in the proband. The mutation was a frameshift mutation caused by a heterozygous 7-bp deletion in the last exon (c.3452_3458delAGAAGCG, p.Glu1151Valfs*57). This study not only expands the mutational spectrum of the LAMB3 gene causing isolated AI but also broadens the understanding of genotype-phenotype correlations.
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Affiliation(s)
- Young-Jae Kim
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Teo J Shin
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Hong-Keun Hyun
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Sang-Hoon Lee
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Zang H Lee
- Department of Cell and Developmental Biology & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Jung-Wook Kim
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
- Department of Molecular Genetics & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
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72
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Ma P, Yan W, Tian Y, He J, Brookes SJ, Wang X. The Importance of Serine Phosphorylation of Ameloblastin on Enamel Formation. J Dent Res 2016; 95:1408-1414. [PMID: 27470066 DOI: 10.1177/0022034516661513] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
FAM20C is a newly identified kinase on the secretory pathway responsible for the phosphorylation of serine residues in the Ser-x-Glu/pSer motifs in several enamel matrix proteins. Fam20C-knockout mice showed severe enamel defects very similar to those in the ameloblastin ( Ambn)-knockout mice, implying that phosphoserines may have a critical role in AMBN function. To test this hypothesis, we generated amelogenin ( Amel) promoter-driven Ambn-transgenic mice, in which Ser48, Ser226, and Ser227 were replaced by aspartic acid (designated as D-Tg) or alanines (designated as A-Tg). The negative charge of aspartic acid is believed to be able to mimic the phosphorylation state of serine, while alanine is a commonly used residue to substitute serine due to their similar structure. Using Western immunoblotting and quantitative polymerase chain reaction, the authors identified transgenic lines expressing transgenes somewhat higher (Tg+) or much higher (Tg++) than endogenous Ambn. The lower incisors collected from 7-d-old and 7-wk-old mice were analyzed by histology, scanning electron microscopy, immunohistochemistry, and Western immunoblotting to examine the morphology and microstructure changes in enamel, as well as the expression pattern of enamel matrix proteins. The A-Tg+ and A-Tg++ mice displayed severe enamel defects in spite of the expression level of transgenes, while the D-Tg+ and D-Tg++ mice showed minor to mild enamel defects, indicating that the D-Tg transgenes disturbed enamel formation less than the A-Tg transgenes did. Our results suggest that the phosphorylation state of serines is likely an essential component for the integrity of AMBN function.
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Affiliation(s)
- P Ma
- 1 Department of Oral Implantology, Beijing Stomatological Hospital, Capital Medical University, Beijing, China.,2 Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, Dallas, TX, USA
| | - W Yan
- 2 Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, Dallas, TX, USA
| | - Y Tian
- 2 Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, Dallas, TX, USA
| | - J He
- 2 Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, Dallas, TX, USA
| | - S J Brookes
- 3 Department of Oral Biology, University of Leeds, St. James's University Hospital, Leeds, UK
| | - X Wang
- 2 Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, Dallas, TX, USA
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FAM83H and casein kinase I regulate the organization of the keratin cytoskeleton and formation of desmosomes. Sci Rep 2016; 6:26557. [PMID: 27222304 PMCID: PMC4879633 DOI: 10.1038/srep26557] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 05/05/2016] [Indexed: 12/23/2022] Open
Abstract
FAM83H is essential for the formation of dental enamel because a mutation in the FAM83H gene causes amelogenesis imperfecta (AI). We previously reported that the overexpression of FAM83H often occurs and disorganizes the keratin cytoskeleton in colorectal cancer cells. We herein show that FAM83H regulates the organization of the keratin cytoskeleton and maintains the formation of desmosomes in ameloblastoma cells. FAM83H is expressed and localized on keratin filaments in human ameloblastoma cell lines and in mouse ameloblasts and epidermal germinative cells in vivo. FAM83H shows preferential localization to keratin filaments around the nucleus that often extend to cell-cell junctions. Alterations in the function of FAM83H by its overexpression, knockdown, or an AI-causing truncated mutant prevent the proper organization of the keratin cytoskeleton in ameloblastoma cells. Furthermore, the AI-causing mutant prevents desmosomal proteins from being localized to cell-cell junctions. The effects of the AI-causing mutant depend on its binding to and possible inhibition of casein kinase I (CK-1). The suppression of CK-1 by its inhibitor, D4476, disorganizes the keratin cytoskeleton. Our results suggest that AI caused by the FAM83H mutation is mediated by the disorganization of the keratin cytoskeleton and subsequent disruption of desmosomes in ameloblasts.
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Abstract
Interactions between enamel matrix proteins are important
for enamel biomineralization. In recent in situ studies, we
showed that the N-terminal proteolytic product of ameloblastin co-localized with
amelogenin around the prism boundaries. However, the molecular mechanisms of such
interactions are still unclear. Here, in order to determine the interacting domains
between amelogenin and ameloblastin, we designed four ameloblastin peptides derived
from different regions of the full-length protein (AB1, AB2 and AB3 at N-terminus,
and AB6 at C-terminus) and studied their interactions with recombinant amelogenin
(rP172), and the tyrosine-rich amelogenin polypeptide (TRAP). A series of amelogenin
Trp variants (rP172(W25), rP172(W45) and rP172(W161)) were also used for intrinsic
fluorescence spectroscopy. Fluorescence spectra of rP172 titrated with AB3, a peptide
encoded by exon 5 of ameloblastin, showed a shift in λmax in a
dose-dependent manner, indicating molecular interactions in the region encoded by
exon 5 of ameloblastin. Circular dichroism (CD) spectra of amelogenin titrated with
AB3 showed that amelogenin was responsible for forming α-helix in the presence of
ameloblastin. Fluorescence spectra of amelogenin Trp variants as well as the spectra
of TRAP titrated with AB3 showed that the N-terminus of amelogenin is involved in the
interaction between ameloblastin and amelogenin. We suggest that macromolecular
co-assembly between amelogenin and ameloblastin may play important roles in enamel
biomineralization. An in vitro approach to study
ameloblastin-amelogenin interactions is presented. Intrinsic fluorescence of tryptophan and Circular Dichroism
were utilized. We report that amelogenin has ameloblastin-binding ability
via its N-terminal close to Trp 25. We report that ameloblastin has amelogenin-binding ability
via a peptide encoded by exon 5. Macromolecular co-assembly between amelogenin and
ameloblastin may play important roles in enamel biomineralization.
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Núñez SM, Chun YHP, Ganss B, Hu Y, Richardson AS, Schmitz JE, Fajardo R, Yang J, Hu JCC, Simmer JP. Maturation stage enamel malformations in Amtn and Klk4 null mice. Matrix Biol 2016; 52-54:219-233. [PMID: 26620968 PMCID: PMC4875837 DOI: 10.1016/j.matbio.2015.11.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 12/14/2022]
Abstract
Amelotin (AMTN) and kallikrein-4 (KLK4) are secreted proteins specialized for enamel biomineralization. We characterized enamel from wild-type, Amtn(-/-), Klk4(-/-), Amtn(+/-)Klk4(+/-) and Amtn(-/-)Klk4(-/-) mice to gain insights into AMTN and KLK4 functions during amelogenesis. All of the null mice were healthy and fertile. The mandibular incisors in Amtn(-/-), Klk4(-/-) and Amtn(-/-)Klk4(-/-) mice were chalky-white and chipped. No abnormalities except in enamel were observed, and no significant differences were detected in enamel thickness or volume, or in rod decussation. Micro-computed tomography (μCT) maximum intensity projections localized the onset of enamel maturation in wild-type incisors distal to the first molar, but mesial to this position in Amtn(-/-), Klk4(-/-) and Amtn(-/-)Klk4(-/-) mice, demonstrating a delay in enamel maturation in Amtn(-/-) incisors. Micro-CT detected significantly reduced enamel mineral density (2.5 and 2.4gHA/cm(3)) in the Klk4(-/-) and Amtn(-/-)Klk4(-/-) mice respectively, compared with wild-type enamel (3.1gHA/cm(3)). Backscatter scanning electron microscopy showed that mineral density progressively diminished with enamel depth in the Klk4(-/-) and Amtn(-/-)Klk4(-/-) mice. The Knoop hardness of the Amtn(-/-) outer enamel was significantly reduced relative to the wild-type and was not as hard as the middle or inner enamel. Klk4(-/-) enamel hardness was significantly reduced at all levels, but the outer enamel was significantly harder than the inner and middle enamel. Thus the hardness patterns of the Amtn(-/-) and Klk4(-/-) mice were distinctly different, while the Amtn(-/-)Klk4(-/-) outer enamel was not as hard as in the Amtn(-/-) and Klk4(-/-) mice. We conclude that AMTN and KLK4 function independently, but are both necessary for proper enamel maturation.
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Affiliation(s)
- Stephanie M Núñez
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl., Ann Arbor, MI, USA 48108.
| | - Yong-Hee P Chun
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX 78240, USA.
| | - Bernhard Ganss
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, 150 College Street, Fitzgerald Building, Toronto, ON M5S 3E2, Canada.
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl., Ann Arbor, MI, USA 48108.
| | - Amelia S Richardson
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl., Ann Arbor, MI, USA 48108.
| | - James E Schmitz
- Department of Orthopaedics, RAYO, Carlisle Center for Bone and Mineral Imaging, School of Medicine, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX, USA.
| | - Roberto Fajardo
- Department of Orthopaedics, RAYO, Carlisle Center for Bone and Mineral Imaging, School of Medicine, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX, USA.
| | - Jie Yang
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl., Ann Arbor, MI, USA 48108; Department of Pediatric Dentistry, School and Hospital of Stomatology, Peking University, 22 South Avenue, Zhongguancun Haidian District, Beijing 100081, PR China.
| | - Jan C-C Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl., Ann Arbor, MI, USA 48108.
| | - James P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl., Ann Arbor, MI, USA 48108.
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Siddiqui S, Al-Jawad M. Enamelin Directs Crystallite Organization at the Enamel-Dentine Junction. J Dent Res 2016; 95:580-7. [PMID: 26912218 DOI: 10.1177/0022034516632745] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Enamel is an acellular material formed by the intricate process of amelogenesis. Disruption caused at the initial stages of development, by means of mutations in the ENAM gene encoding the enamelin protein, results in enamel hypoplasia. Little is known about the consequence of ENAM mutation on the enamel structure at a crystallographic level. The aim of this study was to characterize the structure of ENAM-mutated enamel to develop a deeper understanding of the role of enamelin protein during formation with regard to crystal organization. Synchrotron X-ray microdiffraction (SXRD) and scanning electron microscopy (SEM) have been used to measure and correlate enamel crystallography and microstructure in hypoplastic and healthy enamel. Rietveld refinement carried out on 2-dimensional diffraction patterns, collected from the Advanced Photon Source, were used to quantify changes in the preferred orientation (crystallographic texture) within the labial regions of each tooth slice and then correlated with the local microstructure. In general, healthy deciduous incisors displayed a higher degree of crystal organization across the labial surface in comparison with the hypoplastic enamel. ENAM plays the greatest functional role at the enamel-dentine junction (EDJ), as it was the region that exhibited lowest texture relative to unaffected controls. Other areas within the tooth, however, such as the cusp tip, displayed greater organization in line with healthy enamel, suggesting its effects are restricted to the early stages of enamel secretion. Observed clinically, the surface of ENAM-mutated hypoplastic enamel can appear to be normal, yet severe sub-nano and microstructural defects appear beneath the subsurface layer. Quantitative characterization of the crystallographic properties from enamel with known genotype expands the understanding of enamel formation processes and can aid better clinical diagnosis and tailor-made treatment.
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Affiliation(s)
- S Siddiqui
- Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK iNANO and Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - M Al-Jawad
- Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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77
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ATALAYIN C, TEZEL H, DAGCI T, Karabay YAVASOGLU NU, OKTEM G. Medium modification with bone morphogenetic protein 2 addition for odontogenic differentiation. Braz Oral Res 2016; 30:S1806-83242016000100223. [DOI: 10.1590/1807-3107bor-2016.vol30.0020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 11/09/2015] [Indexed: 01/09/2023] Open
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Pousette Lundgren G, Karsten A, Dahllöf G. Oral health-related quality of life before and after crown therapy in young patients with amelogenesis imperfecta. Health Qual Life Outcomes 2015; 13:197. [PMID: 26651486 PMCID: PMC4676094 DOI: 10.1186/s12955-015-0393-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 12/01/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Amelogenesis imperfecta (AI) is a rare, genetically determined defect in enamel mineralization associated with poor esthetics and dental sensitivity. Because the condition is associated with negative social outcomes, this study evaluated oral health-related quality of life (OHRQoL), dental fear, and dental beliefs before and after early prosthetic crown therapy for AI during adolescence. METHODS The study included 69 patients with AI, aged 6-25 yr: 33 males and 36 females (mean age 14.5 ± 4.3); healthy controls (n = 80), patients with cleft lip and palate (CLP; n = 30), and patients with molar incisor hypomineralization (MIH; n = 39). All matched in age and gender, and all but the CLP group insocioeconomic area. Patients completed three questionnaires measuring OHRQoL (OHIP-14), dental fear (CFSS-DS), and dental beliefs (DBS-R). Twenty-six patients with severe AI between ages 9 and 22 yr received crown therapy and completed the questionnaires twice: before and after therapy. RESULTS OHIP-14 scores were significantly higher among patients with AI (7.0 ± 6.7), MIH (6.8 ± 7.6) and CLP (13.6 ± 12.1) than healthy controls (1.4 ± 2.4) (p < 0.001). After crown therapy, quality of life problems in the 26 patients with severe AI decreased significantly, from 7.8 ± 6.1 to 3.0 ± 4.8 (p < 0.001). Early prosthetic therapy did not increase dental fear or negative attitudes toward dental treatment. CONCLUSIONS OHRQoL increased after early crown therapy in patients with severe AI. Therapy did not increase dental fear or negative attitudes toward dental treatment.
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Affiliation(s)
- Gunilla Pousette Lundgren
- Department of Dental Medicine, Division of Pediatric Dentistry, Karolinska Institutet, POB 4064, SE-141 04, Huddinge, Stockholm, Sweden. .,Department of Pediatric Dentistry, Public Dental Service, Dalarna County, Falun, Sweden.
| | - Agneta Karsten
- Department of Dental Medicine, Division of Orthodontics, Karolinska Institutet, Stockholm, Sweden
| | - Göran Dahllöf
- Department of Dental Medicine, Division of Pediatric Dentistry, Karolinska Institutet, POB 4064, SE-141 04, Huddinge, Stockholm, Sweden
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79
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Suzuki M, Bandoski C, Bartlett JD. Fluoride induces oxidative damage and SIRT1/autophagy through ROS-mediated JNK signaling. Free Radic Biol Med 2015; 89:369-78. [PMID: 26431905 PMCID: PMC4684823 DOI: 10.1016/j.freeradbiomed.2015.08.015] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 08/20/2015] [Accepted: 08/28/2015] [Indexed: 02/07/2023]
Abstract
Fluoride is an effective caries prophylactic, but at high doses can also be an environmental health hazard. Acute or chronic exposure to high fluoride doses can result in dental enamel and skeletal and soft tissue fluorosis. Dental fluorosis is manifested as mottled, discolored, porous enamel that is susceptible to dental caries. Fluoride induces cell stress, including endoplasmic reticulum stress and oxidative stress, which leads to impairment of ameloblasts responsible for dental enamel formation. Recently we reported that fluoride activates SIRT1 and autophagy as an adaptive response to protect cells from stress. However, it still remains unclear how SIRT1/autophagy is regulated in dental fluorosis. In this study, we demonstrate that fluoride exposure generates reactive oxygen species (ROS) and the resulting oxidative damage is counteracted by SIRT1/autophagy induction through c-Jun N-terminal kinase (JNK) signaling in ameloblasts. In the mouse-ameloblast-derived cell line LS8, fluoride induced ROS, mitochondrial damage including cytochrome-c release, up-regulation of UCP2, attenuation of ATP synthesis, and H2AX phosphorylation (γH2AX), which is a marker of DNA damage. We evaluated the effects of the ROS inhibitor N-acetylcysteine (NAC) and the JNK inhibitor SP600125 on fluoride-induced SIRT1/autophagy activation. NAC decreased fluoride-induced ROS generation and attenuated JNK and c-Jun phosphorylation. NAC decreased SIRT1 phosphorylation and formation of the autophagy marker LC3II, which resulted in an increase in the apoptosis mediators γH2AX and cleaved/activated caspase-3. SP600125 attenuated fluoride-induced SIRT1 phosphorylation, indicating that fluoride activates SIRT1/autophagy via the ROS-mediated JNK pathway. In enamel organs from rats or mice treated with 50, 100, or 125 ppm fluoride for 6 weeks, cytochrome-c release and the DNA damage markers 8-oxoguanine, p-ATM, and γH2AX were increased compared to those in controls (0 ppm fluoride). These results suggest that fluoride-induced ROS generation causes mitochondrial damage and DNA damage, which may lead to impairment of ameloblast function. To counteract this impairment, SIRT1/autophagy is induced via JNK signaling to protect cells/ameloblasts from fluoride-induced oxidative damage that may cause dental fluorosis.
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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
| | - Cheryl Bandoski
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA
| | - John D Bartlett
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA.
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Mihalaş E, Matricala L, Chelmuş A, Gheţu N, Petcu A, Paşca S. The Role of Chronic Exposure to Amoxicillin/Clavulanic Acid on the Developmental Enamel Defects in Mice. Toxicol Pathol 2015; 44:61-70. [DOI: 10.1177/0192623315610822] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Amoxicillin used in early childhood may be associated with enamel hypomineralization. Our aim was to assess disturbances of amelogenesis in mice lower incisors induced by chronic administration of amoxicillin/clavulanic acid (AMC). Twenty-eight C57BL/6 male mice, of similar age, randomly divided into a control and 3 treatment groups ( n = 7) received subcutaneous injection, once per day, for 60 days: 50, 100, and 150 mg/kg BW of AMC. Scanning electron microscopy/energy dispersive X-ray spectroscopy analysis in AMC treatment groups showed higher content in F and a decrease in P and Ca. Morphology changes ranged from scratched patterns, and small isolated pits-like enamel loss, to generalized demineralized enamel surface, giving a rough, foamy, scaly, or even cracked eggshell appearance to the affected areas. Histological analysis showed disturbances of maturation ameloblasts, which were less organized, with increased amounts of clear vacuoles in the cytoplasm and slightly more elongated and less condensed nucleus. Additionally, they were often detached from the enamel matrix. Transitional ameloblasts formed underlying the cysts of varied sizes. In conclusion, AMC dose-dependently affect ameloblast functions especially in the maturation phase, causing hypomineralized enamel formation with quantitative and/or qualitative defects.
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Affiliation(s)
- Eugeniu Mihalaş
- Department of Pedodontics, “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Romania
| | - Lavinia Matricala
- “Petru Poni” Institute of Macromolecular Chemistry of Romanian Academy, Iasi, Romania
| | - Alina Chelmuş
- Department of Plastic and Reconstructive Surgery, Regional Oncology Institute, Iasi, Romania
- Center for Simulation and Training in Surgery, “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Romania
| | - Nicolae Gheţu
- Department of Plastic and Reconstructive Surgery, Regional Oncology Institute, Iasi, Romania
- Center for Simulation and Training in Surgery, “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Romania
| | - Ana Petcu
- Department of Pedodontics, “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Romania
| | - Sorin Paşca
- Department of Pathology, “Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Iasi, Romania
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Liu C, Niu Y, Zhou X, Xu X, Yang Y, Zhang Y, Zheng L. Cell cycle control, DNA damage repair, and apoptosis-related pathways control pre-ameloblasts differentiation during tooth development. BMC Genomics 2015; 16:592. [PMID: 26265206 PMCID: PMC4534026 DOI: 10.1186/s12864-015-1783-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 07/16/2015] [Indexed: 02/05/2023] Open
Abstract
Background Ameloblast differentiation is the most critical stepwise process in amelogenesis, and it is controlled by precise molecular events. To better understand the mechanism controlling pre-ameloblasts (PABs) differentiation into secretory ameloblasts (SABs), a more precise identification of molecules and signaling networks will elucidate the mechanisms governing enamel formation and lay a foundation for enamel regeneration. Results We analyzed transcriptional profiles of human PABs and SABs. From a total of 28,869 analyzed transcripts, we identified 923 differentially expressed genes (DEGs) with p < 0.05 and Fold-change > 2. Among the DEGs, 647 genes showed elevated expression in PABs compared to SABs. Notably, 38 DEGs displayed greater than eight-fold changes. Comparative analysis revealed that highly expressed genes in PABs were involved in cell cycle control, DNA damage repair and apoptosis, while highly expressed genes in SABs were related to cell adhesion and extracellular matrix. Moreover, coexpression network analysis uncovered two highly conserved sub-networks contributing to differentiation, containing transcription regulators (RUNX2, ETV1 and ETV5), solute carrier family members (SLC15A1 and SLC7A11), enamel matrix protein (MMP20), and a polymodal excitatory ion channel (TRPA1). Conclusions By combining comparative analysis and coexpression networks, this study provides novel biomarkers and research targets for ameloblast differentiation and the potential for their application in enamel regeneration. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1783-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chengcheng Liu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
| | - Yulong Niu
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China.
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
| | - Xin Xu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
| | - Yi Yang
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China.
| | - Yan Zhang
- Department of Orofacial Sciences, University of California, San Francisco, CA, 94143, USA.
| | - Liwei Zheng
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
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Abstract
Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization in vitro, and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics. We review the most recent findings on amelogenin secondary and tertiary structural properties with a focus on its interactions with different targets including other enamel proteins, apatite mineral, and phospholipids. Following a brief overview of enamel hierarchical structure and its mechanical properties we will present the state-of-the-art strategies in the biomimetic reconstruction of human enamel.
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Affiliation(s)
- Qichao Ruan
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
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MicroRNA 224 Regulates Ion Transporter Expression in Ameloblasts To Coordinate Enamel Mineralization. Mol Cell Biol 2015; 35:2875-90. [PMID: 26055330 DOI: 10.1128/mcb.01266-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 06/04/2015] [Indexed: 02/05/2023] Open
Abstract
Enamel mineralization is accompanied by the release of protons into the extracellular matrix, which is buffered to regulate the pH value in the local microenvironment. The present study aimed to investigate the role of microRNA 224 (miR-224) as a regulator of SLC4A4 and CFTR, encoding the key buffering ion transporters, in modulating enamel mineralization. miR-224 was significantly downregulated as ameloblasts differentiated, in parallel with upregulation of SLC4A4 and CFTR. Overexpression of miR-224 downregulated SLC4A4 and CFTR expression in cultured human epithelial cells. A microRNA luciferase assay confirmed the specific binding of miR-224 to the 3' untranslated regions (UTRs) of SLC4A4 and CFTR mRNAs, thereby inhibiting protein translation. miR-224 agomir injection in mouse neonatal incisors resulted in normal enamel length and thickness, but with disturbed organization of the prism structure and deficient crystal growth. Moreover, the enamel Ca/P ratio and microhardness were markedly reduced after miR-224 agomir administration. These results demonstrate that miR-224 plays a pivotal role in fine tuning enamel mineralization by modulating SLC4A4 and CFTR to maintain pH homeostasis and support enamel mineralization.
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84
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Kawasaki K, Amemiya CT. SCPP genes in the coelacanth: tissue mineralization genes shared by sarcopterygians. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2015; 322:390-402. [PMID: 25243252 DOI: 10.1002/jez.b.22546] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The coelacanth is the basal-most extant sarcopterygian that has teeth and tooth-like structures, comprising bone, dentin, and enamel or enameloid. Formation of these tissues involves many members of the secretory calcium-binding protein (SCPP) family. In tetrapods, acidic-residue-rich SCPPs are used in mineralization of bone and dentin, whereas Pro/Gln-rich SCPPs participate in enamel formation. Teleosts also employ many SCPPs for tissue mineralization. Nevertheless, the repertoire of SCPPs is largely different in teleosts and tetrapods; hence, filling this gap would be critical to elucidate early evolution of mineralized tissues in osteichthyans. In the present study, we searched for SCPP genes in the coelacanth genome and identified 11, of which two have clear orthologs in both tetrapods and teleosts, seven only in tetrapods, and two in neither of them. Given the divergence times of these vertebrate lineages, our discovery of this many SCPP genes shared between the coelacanth and tetrapods, but not with teleosts, suggests a complicated evolutionary scheme of SCPP genes in early osteichthyans. Our investigation also revealed both conserved and derived characteristics of SCPPs in the coelacanth and other vertebrates. Notably, acidic SCPPs independently evolved various acidic repeats in different lineages, while maintaining high acidity, presumably important for interactions with calcium. Furthermore, the three Pro/Gln-rich SCPP genes, required for mineralizing enamel matrix and confirmed only in tetrapods, were all identified in the coelacanth, strongly suggesting that enamel is equivalent in the coelacanth and tetrapods. This finding corroborates the previous proposition that true enamel evolved much earlier than the origin of tetrapods.
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85
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Abbarin N, San Miguel S, Holcroft J, Iwasaki K, Ganss B. The enamel protein amelotin is a promoter of hydroxyapatite mineralization. J Bone Miner Res 2015; 30:775-85. [PMID: 25407797 DOI: 10.1002/jbmr.2411] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 11/04/2014] [Accepted: 11/14/2014] [Indexed: 01/29/2023]
Abstract
Amelotin (AMTN) is a recently discovered protein that is specifically expressed during the maturation stage of dental enamel formation. It is localized at the interface between the enamel surface and the apical surface of ameloblasts. AMTN knock-out mice have hypomineralized enamel, whereas transgenic mice overexpressing AMTN have a compact but disorganized enamel hydroxyapatite (HA) microstructure, indicating a possible involvement of AMTN in regulating HA mineralization directly. In this study, we demonstrated that recombinant human (rh) AMTN dissolved in a metastable buffer system, based on light scattering measurements, promotes HA precipitation. The mineral precipitates were characterized by scanning and transmission electron microscopy and electron diffraction. Colloidal gold immunolabeling of AMTN in the mineral deposits showed that protein molecules were associated with HA crystals. The binding affinity of rh-AMTN to HA was found to be comparable to that of amelogenin, the major protein of the forming enamel matrix. Overexpression of AMTN in mouse calvaria cells also increased the formation of calcium deposits in the culture medium. Overexpression of AMTN during the secretory stage of enamel formation in vivo resulted in rapid and uncontrolled enamel mineralization. Site-specific mutagenesis of the potential serine phosphorylation motif SSEEL reduced the in vitro mineral precipitation to less than 25%, revealing that this motif is important for the HA mineralizing function of the protein. A synthetic short peptide containing the SSEEL motif was only able to facilitate mineralization in its phosphorylated form ((P)S(P) SEEL), indicating that this motif is necessary but not sufficient for the mineralizing properties of AMTN. These findings demonstrate that AMTN has a direct influence on biomineralization by promoting HA mineralization and suggest a critical role for AMTN in the formation of the compact aprismatic enamel surface layer during the maturation stage of amelogenesis.
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Affiliation(s)
- Nastaran Abbarin
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, Canada
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86
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Melin L, Lundgren J, Malmberg P, Norén JG, Taube F, Cornell DH. XRMA and ToF-SIMS Analysis of Normal and Hypomineralized Enamel. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2015; 21:407-421. [PMID: 25674916 DOI: 10.1017/s1431927615000033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Molar incisor hypomineralization (MIH) is a developmental disturbance of the enamel. This study presents analyses of hypomineralized and normal enamel in first molar teeth diagnosed with MIH, utilizing time-of-flight secondary ion mass spectrometry area analyses and X-ray microanalysis of area and spot profiles in uncoated samples between gold lines which provide electrical conductivity. Statistical analysis of mean values allows discrimination of normal from MIH enamel, which has higher Mg and lower Na and P. Inductive analysis using complete data sets for profiles from the enamel surface to the enamel-dentin junction found that Mg, Cl and position in the profile provide useful discrimination criteria. Element profiles provide a visual complement to the inductive analysis and several elements also provide insight into the development of both normal and MIH enamel. The higher Mg content and different Cl profiles of hypomineralized enamel compared with normal enamel are probably related to a relatively short period during the development of ameloblasts between birth and the 1st year of life.
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Affiliation(s)
- Lisa Melin
- 1Department of Pediatric Dentistry,Institute of Odontology at the Sahlgrenska Academy,University of Gothenburg,P.O. Box 450,SE 405 30 Gothenburg,Sweden
| | - Jesper Lundgren
- 2Department of Psychology,University of Gothenburg,P.O. Box 500,SE 405 30 Gothenburg,Sweden
| | - Per Malmberg
- 3Department of Chemical and Biological Engineering,Chalmers University of Technology,Kemivägen 10,412 96 Gothenburg,Sweden
| | - Jörgen G Norén
- 1Department of Pediatric Dentistry,Institute of Odontology at the Sahlgrenska Academy,University of Gothenburg,P.O. Box 450,SE 405 30 Gothenburg,Sweden
| | - Fabian Taube
- 4Department of Occupational and Environmental Medicine,Sahlgrenska University Hospital,P.O. Box 414,SE 405 30 Gothenburg,Sweden
| | - David H Cornell
- 5Department of Earth Sciences,University of Gothenburg,P.O. Box 460,SE 405 30 Gothenburg,Sweden
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87
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Zhang Z, Tian H, Lv P, Wang W, Jia Z, Wang S, Zhou C, Gao X. Transcriptional factor DLX3 promotes the gene expression of enamel matrix proteins during amelogenesis. PLoS One 2015; 10:e0121288. [PMID: 25815730 PMCID: PMC4376716 DOI: 10.1371/journal.pone.0121288] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Accepted: 01/29/2015] [Indexed: 11/25/2022] Open
Abstract
Mutation of distal-less homeobox 3 (DLX3) is responsible for human tricho-dento-osseous syndrome (TDO) with amelogenesis imperfecta, indicating a crucial role of DLX3 in amelogenesis. However, the expression pattern of DLX3 and its specific function in amelogenesis remain largely unknown. The aim of this study was to investigate the effects of DLX3 on enamel matrix protein (EMP) genes. By immunohistochemistry assays of mouse tooth germs, stronger immunostaining of DLX3 protein was identified in ameloblasts in the secretory stage than in the pre-secretory and maturation stages, and the same pattern was found for Dlx3 mRNA using Realtime PCR. In a mouse ameloblast cell lineage, forced expression of DLX3 up-regulated the expression of the EMP genes Amelx, Enam, Klk4, and Odam, whereas knockdown of DLX3 down-regulated these four EMP genes. Further, bioinformatics, chromatin immunoprecipitation, and luciferase assays revealed that DLX3 transactivated Enam, Amelx, and Odam through direct binding to their enhancer regions. Particularly, over-expression of mutant-DLX3 (c.571_574delGGGG, responsible for TDO) inhibited the activation function of DLX3 on expression levels and promoter activities of the Enam, Amelx, and Odam genes. Together, our data show that DLX3 promotes the expression of the EMP genes Amelx, Enam, Klk4, and Odam in amelogenesis, while mutant-DLX3 disrupts this regulatory function, thus providing insights into the molecular mechanisms underlying the enamel defects of TDO disease.
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Affiliation(s)
- Zhichun Zhang
- Department of Cariology and Endodontology, School and Hospital of Stomatology, Peking University, Beijing, PR China
| | - Hua Tian
- Department of Cariology and Endodontology, School and Hospital of Stomatology, Peking University, Beijing, PR China
- * E-mail: (HT); (CZ)
| | - Ping Lv
- Department of Cariology and Endodontology, School and Hospital of Stomatology, Peking University, Beijing, PR China
| | - Weiping Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, PR China
| | - Zhuqing Jia
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, PR China
| | - Sainan Wang
- Department of Cariology and Endodontology, School and Hospital of Stomatology, Peking University, Beijing, PR China
| | - Chunyan Zhou
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, PR China
- * E-mail: (HT); (CZ)
| | - Xuejun Gao
- Department of Cariology and Endodontology, School and Hospital of Stomatology, Peking University, Beijing, PR China
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88
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Cui J, Xiao J, Tagliabracci VS, Wen J, Rahdar M, Dixon JE. A secretory kinase complex regulates extracellular protein phosphorylation. eLife 2015; 4:e06120. [PMID: 25789606 PMCID: PMC4421793 DOI: 10.7554/elife.06120] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/18/2015] [Indexed: 12/19/2022] Open
Abstract
Although numerous extracellular phosphoproteins have been identified, the protein kinases within the secretory pathway have only recently been discovered, and their regulation is virtually unexplored. Fam20C is the physiological Golgi casein kinase, which phosphorylates many secreted proteins and is critical for proper biomineralization. Fam20A, a Fam20C paralog, is essential for enamel formation, but the biochemical function of Fam20A is unknown. Here we show that Fam20A potentiates Fam20C kinase activity and promotes the phosphorylation of enamel matrix proteins in vitro and in cells. Mechanistically, Fam20A is a pseudokinase that forms a functional complex with Fam20C, and this complex enhances extracellular protein phosphorylation within the secretory pathway. Our findings shed light on the molecular mechanism by which Fam20C and Fam20A collaborate to control enamel formation, and provide the first insight into the regulation of secretory pathway phosphorylation. DOI:http://dx.doi.org/10.7554/eLife.06120.001 Some proteins must be modified in order to work effectively. One common modification is to add a phosphate group to the protein, which is performed by enzymes called protein kinases. Although most of the protein kinases work on proteins inside the cell, it was discovered recently that a small group of kinases work within the ‘secretory pathway’ and modify proteins that are released (or secreted) out of cells. One such secretory pathway kinase—called Fam20C—phosphorylates a wide range of secreted proteins and helps to ensure the proper development of bones and teeth. Specifically, Fam20C and a closely related protein called Fam20A are important for forming enamel, the hardest substance in human body, which makes up the outer surface of teeth. However, the exact role of Fam20A is unknown. Cui et al. now show that Fam20A binds to Fam20C, and this increases the ability of Fam20C to phosphorylate the proteins that form the ‘matrix’ that guides the deposition of the enamel minerals. Furthermore, mutations in Fam20A lead to the inefficient phosphorylation of enamel matrix proteins by Fam20C, and prevent proper enamel formation. The results raise the possibility that similar mechanisms of secretory kinase activation may also be important in other biological processes where many secreted proteins need to be phosphorylated rapidly. DOI:http://dx.doi.org/10.7554/eLife.06120.002
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Affiliation(s)
- Jixin Cui
- Department of Pharmacology, University of California, San Diego, La Jolla, United States
| | - Junyu Xiao
- Department of Pharmacology, University of California, San Diego, La Jolla, United States
| | - Vincent S Tagliabracci
- Department of Pharmacology, University of California, San Diego, La Jolla, United States
| | - Jianzhong Wen
- Department of Pharmacology, University of California, San Diego, La Jolla, United States
| | - Meghdad Rahdar
- Department of Pharmacology, University of California, San Diego, La Jolla, United States
| | - Jack E Dixon
- Department of Pharmacology, University of California, San Diego, La Jolla, United States
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89
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Wang X, Zhao Y, Yang Y, Qin M. Novel ENAM and LAMB3 mutations in Chinese families with hypoplastic amelogenesis imperfecta. PLoS One 2015; 10:e0116514. [PMID: 25769099 PMCID: PMC4358960 DOI: 10.1371/journal.pone.0116514] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 12/10/2014] [Indexed: 11/18/2022] Open
Abstract
Amelogenesis imperfecta is a group of inherited diseases affecting the quality and quantity of dental enamel. To date, mutations in more than ten genes have been associated with non-syndromic amelogenesis imperfecta (AI). Among these, ENAM and LAMB3 mutations are known to be parts of the etiology of hypoplastic AI in human cases. When both alleles of LAMB3 are defective, it could cause junctional epidermolysis bullosa (JEB), while with only one mutant allele in the C-terminus of LAMB3, it could result in severe hypoplastic AI without skin fragility. We enrolled three Chinese families with hypoplastic autosomal-dominant AI. Despite the diagnosis falling into the same type, the characteristics of their enamel hypoplasia were different. Screening of ENAM and LAMB3 genes was performed by direct sequencing of genomic DNA from blood samples. Disease-causing mutations were identified and perfectly segregated with the enamel defects in three families: a 19-bp insertion mutation in the exon 7 of ENAM (c.406_407insTCAAAAAAGCCGACCACAA, p.K136Ifs*16) in Family 1, a single-base deletion mutation in the exon 5 of ENAM (c. 139delA, p. M47Cfs*11) in Family 2, and a LAMB3 nonsense mutation in the last exon (c.3466C>T, p.Q1156X) in Family 3. Our results suggest that heterozygous mutations in ENAM and LAMB3 genes can cause hypoplastic AI with markedly different phenotypes in Chinese patients. And these findings extend the mutation spectrum of both genes and can be used for mutation screening of AI in the Chinese population.
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Affiliation(s)
- Xin Wang
- Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
| | - Yuming Zhao
- Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
| | - Yuan Yang
- Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
| | - Man Qin
- Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
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90
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Seymen F, Lee KE, Koruyucu M, Gencay K, Bayram M, Tuna EB, Lee ZH, Kim JW. Novel ITGB6 mutation in autosomal recessive amelogenesis imperfecta. Oral Dis 2015; 21:456-61. [PMID: 25431241 PMCID: PMC4440386 DOI: 10.1111/odi.12303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 11/18/2014] [Accepted: 11/21/2014] [Indexed: 11/30/2022]
Abstract
Objective Hereditary defects in tooth enamel formation, amelogenesis imperfecta (AI), can be non-syndromic or syndromic phenotype. Integrins are signaling proteins that mediate cell–cell and cell–extracellular matrix communication, and their involvement in tooth development is well known. The purposes of this study were to identify genetic cause of an AI family and molecular pathogenesis underlying defective enamel formation. Materials and Methods We recruited a Turkish family with isolated AI and performed mutational analyses to clarify the underlying molecular genetic etiology. Results Autozygosity mapping and exome sequencing identified a novel homozygous ITGB6 transversion mutation in exon 4 (c.517G>C, p.Gly173Arg). The glycine at this position in the middle of the βI-domain is conserved among a wide range of vertebrate orthologs and human paralogs. Clinically, the enamel was generally thin and pitted with pigmentation. Thicker enamel was noted at the cervical area of the molars. Conclusions In this study, we identified a novel homozygous ITGB6 mutation causing isolated AI, and this advances the understanding of normal and pathologic enamel development.
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Affiliation(s)
- F Seymen
- Department of Pedodontics, Faculty of Dentistry Istanbul University, Istanbul, Turkey
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91
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Ruan Q, Moradian-Oldak J. Amelogenin and enamel biomimetics. J Mater Chem B 2015. [DOI: 10.1039/c5tb00163c and 21=21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mature tooth enamel is acellular and does not regenerate itself.
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Affiliation(s)
- Qichao Ruan
- Center for Craniofacial Molecular Biology
- Herman Ostrow School of Dentistry
- University of Southern California
- Los Angeles
- USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology
- Herman Ostrow School of Dentistry
- University of Southern California
- Los Angeles
- USA
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92
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Mitsiadis TA, Filatova A, Papaccio G, Goldberg M, About I, Papagerakis P. Distribution of the amelogenin protein in developing, injured and carious human teeth. Front Physiol 2014; 5:477. [PMID: 25540624 PMCID: PMC4261713 DOI: 10.3389/fphys.2014.00477] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 11/22/2014] [Indexed: 12/02/2022] Open
Abstract
Amelogenin is the major enamel matrix protein with key roles in amelogenesis. Although for many decades amelogenin was considered to be exclusively expressed by ameloblasts, more recent studies have shown that amelogenin is also expressed in other dental and no-dental cells. However, amelogenin expression in human tissues remains unclear. Here, we show that amelogenin protein is not only expressed during human embryonic development but also in pathological conditions such as carious lesions and injuries after dental cavity preparation. In developing embryonic teeth, amelogenin stage-specific expression is found in all dental epithelia cell populations but with different intensities. In the different layers of enamel matrix, waves of positive vs. negative immunostaining for amelogenin are detected suggesting that the secretion of amelogenin protein is orchestrated by a biological clock. Amelogenin is also expressed transiently in differentiating odontoblasts during predentin formation, but was absent in mature functional odontoblasts. In intact adult teeth, amelogenin was not present in dental pulp, odontoblasts, and dentin. However, in injured and carious adult human teeth amelogenin is strongly re-expressed in newly differentiated odontoblasts and is distributed in the dentinal tubuli under the lesion site. In an in vitro culture system, amelogenin is expressed preferentially in human dental pulp cells that start differentiating into odontoblast-like cells and form mineralization nodules. These data suggest that amelogenin plays important roles not only during cytodifferentiation, but also during tooth repair processes in humans.
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Affiliation(s)
- Thimios A Mitsiadis
- Orofacial Development and Regeneration Unit, Faculty of Medicine, Institute of Oral Biology, ZZM, University of Zurich Zurich, Switzerland
| | - Anna Filatova
- Orofacial Development and Regeneration Unit, Faculty of Medicine, Institute of Oral Biology, ZZM, University of Zurich Zurich, Switzerland
| | - Gianpaolo Papaccio
- Dipartimento di Medicina Sperimentale, Sezione di Biotecnologie, Istologia Medica e Biologia Molecolare, Seconda Università Degli Studi di Napoli Napoli, Italy
| | - Michel Goldberg
- INSERM UMR-S 1124, Biomédicale des Saints Pères, University Paris Descartes Paris, France
| | - Imad About
- CNRS, Institut des Sciences du Mouvement UMR 7287, Aix-Marseille Université Marseille, France
| | - Petros Papagerakis
- Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan Ann Arbor, USA ; Center for Organogenesis, School of Medicine, University of Michigan Ann Arbor, USA ; Center for Computational Medicine and Bioinformatics, School of Medicine, University of Michigan Ann Arbor, USA
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93
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Sa Y, Liang S, Ma X, Lu S, Wang Z, Jiang T, Wang Y. Compositional, structural and mechanical comparisons of normal enamel and hypomaturation enamel. Acta Biomater 2014; 10:5169-5177. [PMID: 25172537 DOI: 10.1016/j.actbio.2014.08.023] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 07/29/2014] [Accepted: 08/19/2014] [Indexed: 12/20/2022]
Abstract
Hypomaturation amelogenesis imperfecta is a hereditary disorder of the enamel that severely influences the function, aesthetics and psychosocial well-being of patients. In this study, we performed a thorough comparison of normal and hypomaturation enamel through a series of systematical tests on human permanent molars to understand the biomineralization process during pathological amelogenesis. The results of microcomputed tomography, scanning electron microscopy, Fourier transform infrared, Raman spectroscopy, microzone X-ray diffraction, thermal gravimetric analysis, energy diffraction spectrum and Vickers microhardness testing together show dramatic contrasts between hypomaturation enamel and normal enamel in terms of their hierarchical structures, spectral features, crystallographic characteristics, thermodynamic behavior, mineral distribution and mechanical property. Our current study highlights the importance of the organic matrix during the amelogenesis process. It is found that the retention of the organic matrix will influence the quantity, quality and distribution of mineral crystals, which will further demolish the hierarchical architecture of the enamel and affect the related mechanical property. In addition, the high carbonate content in hypomaturation enamel influences the crystallinity, crystal size and solubility of hydroxyapatite crystals. These results deepen our understanding of hypomaturation enamel biomineralization during amelogenesis, explain the clinical manifestations of hypomaturation enamel, provide fundamental evidence to help dentists choose optimal therapeutic strategies and lead to improved biofabrication and gene therapies.
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Affiliation(s)
- Yue Sa
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, People's Republic of China
| | - Shanshan Liang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, People's Republic of China
| | - Xiao Ma
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, People's Republic of China
| | - Steven Lu
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Zhejun Wang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, People's Republic of China
| | - Tao Jiang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, People's Republic of China.
| | - Yining Wang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, People's Republic of China.
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94
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Yin K, Hacia JG, Zhong Z, Paine ML. Genome-wide analysis of miRNA and mRNA transcriptomes during amelogenesis. BMC Genomics 2014; 15:998. [PMID: 25406666 PMCID: PMC4254193 DOI: 10.1186/1471-2164-15-998] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Accepted: 10/23/2014] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND In the rodent incisor during amelogenesis, as ameloblast cells transition from secretory stage to maturation stage, their morphology and transcriptome profiles change dramatically. Prior whole genome transcriptome analysis has given a broad picture of the molecular activities dominating both stages of amelogenesis, but this type of analysis has not included miRNA transcript profiling. In this study, we set out to document which miRNAs and corresponding target genes change significantly as ameloblasts transition from secretory- to maturation-stage amelogenesis. RESULTS Total RNA samples from both secretory- and maturation-stage rat enamel organs were subjected to genome-wide miRNA and mRNA transcript profiling. We identified 59 miRNAs that were differentially expressed at the maturation stage relative to the secretory stage of enamel development (False Discovery Rate (FDR)<0.05, fold change (FC)≥1.8). In parallel, transcriptome profiling experiments identified 1,729 mRNA transcripts that were differentially expressed in the maturation stage compared to the secretory stage (FDR<0.05, FC≥1.8). Based on bioinformatics analyses, 5.8% (629 total) of these differentially expressed genes (DEGS) were highlighted as being the potential targets of 59 miRNAs that were differentially expressed in the opposite direction, in the same tissue samples. Although the number of predicted target DEGs was not higher than baseline expectations generated by examination of stably expressed miRNAs, Gene Ontology (GO) analysis showed that these 629 DEGS were enriched for ion transport, pH regulation, calcium handling, endocytotic, and apoptotic activities. Seven differentially expressed miRNAs (miR-21, miR-31, miR-488, miR-153, miR-135b, miR-135a and miR298) in secretory- and/or maturation-stage enamel organs were confirmed by in situ hybridization. Further, we used luciferase reporter assays to provide evidence that two of these differentially expressed miRNAs, miR-153 and miR-31, are potential regulators for their predicated target mRNAs, Lamp1 (miR-153) and Tfrc (miR-31). CONCLUSIONS In conclusion, these data indicate that miRNAs exhibit a dynamic expression pattern during the transition from secretory-stage to maturation-stage tooth enamel formation. Although they represent only one of numerous mechanisms influencing gene activities, miRNAs specific to the maturation stage could be involved in regulating several key processes of enamel maturation by influencing mRNA stability and translation.
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Affiliation(s)
- Kaifeng Yin
- />Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, CSA103, Los Angeles, CA 90033 USA
| | - Joseph G Hacia
- />Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSA140, Los Angeles, CA 90033 USA
| | - Zhe Zhong
- />Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, CSA103, Los Angeles, CA 90033 USA
| | - Michael L Paine
- />Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, CSA103, Los Angeles, CA 90033 USA
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95
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Katsura KA, Horst JA, Chandra D, Le TQ, Nakano Y, Zhang Y, Horst OV, Zhu L, Le MH, DenBesten PK. WDR72 models of structure and function: a stage-specific regulator of enamel mineralization. Matrix Biol 2014; 38:48-58. [PMID: 25008349 PMCID: PMC4185229 DOI: 10.1016/j.matbio.2014.06.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 06/21/2014] [Accepted: 06/26/2014] [Indexed: 12/18/2022]
Abstract
Amelogenesis Imperfecta (AI) is a clinical diagnosis that encompasses a group of genetic mutations, each affecting processes involved in tooth enamel formation and thus, result in various enamel defects. The hypomaturation enamel phenotype has been described for mutations involved in the later stage of enamel formation, including Klk4, Mmp20, C4orf26, and Wdr72. Using a candidate gene approach we discovered a novel Wdr72 human mutation in association with AI to be a 5-base pair deletion (c.806_810delGGCAG; p.G255VfsX294). To gain insight into the function of WDR72, we used computer modeling of the full-length human WDR72 protein structure and found that the predicted N-terminal sequence forms two beta-propeller folds with an alpha-solenoid tail at the C-terminus. This domain iteration is characteristic of vesicle coat proteins, such as beta'-COP, suggesting a role for WDR72 in the formation of membrane deformation complexes to regulate intracellular trafficking. Our Wdr72 knockout mouse model (Wdr72(-/-)), containing a LacZ reporter knock-in, exhibited hypomineralized enamel similar to the AI phenotype observed in humans with Wdr72 mutations. MicroCT scans of Wdr72(-/-) mandibles affirmed the hypomineralized enamel phenotype occurring at the onset of the maturation stage. H&E staining revealed a shortened height phenotype in the Wdr72(-/-) ameloblasts with retained proteins in the enamel matrix during maturation stage. H(+)/Cl(-) exchange transporter 5 (CLC5), an early endosome acidifier, was co-localized with WDR72 in maturation-stage ameloblasts and decreased in Wdr72(-/-) maturation-stage ameloblasts. There were no obvious differences in RAB4A and LAMP1 immunostaining of Wdr72(-/-) mice as compared to wildtype controls. Moreover, Wdr72(-/-) ameloblasts had reduced amelogenin immunoreactivity, suggesting defects in amelogenin fragment resorption from the matrix. These data demonstrate that WDR72 has a major role in enamel mineralization, most notably during the maturation stage, and suggest a function involving endocytic vesicle trafficking, possibly in the removal of amelogenin proteins.
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Affiliation(s)
- K A Katsura
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - J A Horst
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - D Chandra
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - T Q Le
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - Y Nakano
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - Y Zhang
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - O V Horst
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - L Zhu
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - M H Le
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - P K DenBesten
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
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96
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Outcome of restorative treatment in young patients with amelogenesis imperfecta. a cross-sectional, retrospective study. J Dent 2014; 42:1382-9. [PMID: 25107287 DOI: 10.1016/j.jdent.2014.07.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 07/25/2014] [Accepted: 07/28/2014] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES The longevity of dental restorations in patients with amelogenesis imperfecta (AI) is limited. The aim of this paper is to compare oral health and longevity of dental restorations in a group of young patients with AI compared to a control group. METHODS Patients included were 82 patients with AI, 40 boys and 42 girls, 6 to 25 years old (mean age 14.5±4.3 years) and a control group matched in age, gender and residential area. All patients received an examination recording dental caries, gingivitis, previous therapy, replaced restorations, tooth sensitivity, and number of dental visits. Patient dental records, extending from 6 to 10 years before the study, provided data on previous care. RESULTS Annual mean number of dental visits in the AI group was 2.9±1.7 compared to 1.9±1.2 in the control group (p<0.001). DMFS was 8.1±15.6 in the AI group compared to 1.0±2.0 in the control group (p<0.001). The longevity of dental restorations was significantly lower in the patients with AI, with 24.7±35.1% of the AI group requiring replacement of fillings during the observation period compared to 9.23±23.7% in the control group (p=0.001). Patients with hypomineralized/hypomaturized AI have restorations of shorter longevity than those with hypoplastic AI (p<0.01). Porcelain crowns had significantly longer survival than composite resin materials in the AI group (p<0.001). Clinical Significance This study shows the need for long-lasting restorative solutions for patients with AI. It also shows the importance of establishing an early permanent therapy plan for these patients to avoid frequent dental visits.
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97
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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: 41] [Impact Index Per Article: 4.1] [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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98
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Guan X, Bidlack FB, Stokes N, Bartlett JD. E-cadherin can replace N-cadherin during secretory-stage enamel development. PLoS One 2014; 9:e102153. [PMID: 25014356 PMCID: PMC4094553 DOI: 10.1371/journal.pone.0102153] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/16/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND N-cadherin is a cell-cell adhesion molecule and deletion of N-cadherin in mice is embryonic lethal. During the secretory stage of enamel development, E-cadherin is down-regulated and N-cadherin is specifically up-regulated in ameloblasts when groups of ameloblasts slide by one another to form the rodent decussating enamel rod pattern. Since N-cadherin promotes cell migration, we asked if N-cadherin is essential for ameloblast cell movement during enamel development. METHODOLOGY/PRINCIPAL FINDINGS The enamel organ, including its ameloblasts, is an epithelial tissue and for this study a mouse strain with N-cadherin ablated from epithelium was generated. Enamel from wild-type (WT) and N-cadherin conditional knockout (cKO) mice was analyzed. μCT and scanning electron microscopy showed that thickness, surface structure, and prism pattern of the cKO enamel looked identical to WT. No significant difference in hardness was observed between WT and cKO enamel. Interestingly, immunohistochemistry revealed the WT and N-cadherin cKO secretory stage ameloblasts expressed approximately equal amounts of total cadherins. Strikingly, E-cadherin was not normally down-regulated during the secretory stage in the cKO mice suggesting that E-cadherin can compensate for the loss of N-cadherin. Previously it was demonstrated that bone morphogenetic protein-2 (BMP2) induces E- and N-cadherin expression in human calvaria osteoblasts and we show that the N-cadherin cKO enamel organ expressed significantly more BMP2 and significantly less of the BMP antagonist Noggin than did WT enamel organ. CONCLUSIONS/SIGNIFICANCE The E- to N-cadherin switch at the secretory stage is not essential for enamel development or for forming the decussating enamel rod pattern. E-cadherin can substitute for N-cadherin during these developmental processes. Bmp2 expression may compensate for the loss of N-cadherin by inducing or maintaining E-cadherin expression when E-cadherin is normally down-regulated. Notably, this is the first demonstration of a natural endogenous increase in E-cadherin expression due to N-cadherin ablation in a healthy developing tissue.
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Affiliation(s)
- Xiaomu Guan
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge, Massachusetts, United States of America
| | - Felicitas B. Bidlack
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge, Massachusetts, United States of America
| | - Nicole Stokes
- Laboratory of Mammalian Cell Biology and Development, Howard Hughes Medical Institute, The Rockefeller University, New York, New York, 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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99
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Bartlett JD, Simmer JP. Kallikrein-related peptidase-4 (KLK4): role in enamel formation and revelations from ablated mice. Front Physiol 2014; 5:240. [PMID: 25071586 PMCID: PMC4082239 DOI: 10.3389/fphys.2014.00240] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 06/10/2014] [Indexed: 12/26/2022] Open
Abstract
Enamel development occurs in stages. During the secretory stage, a soft protein rich enamel layer is produced that expands to reach its final thickness. During the maturation stage, proteins are removed and the enamel matures into the hardest substance in the body. KLK4 is expressed during the transition from secretory to the maturation stage and its expression continues throughout maturation. KLK4 is a glycosylated chymotrypsin-like serine protease that cleaves enamel matrix proteins prior to their export out of the hardening enamel layer. Mutations in KLK4 can cause autosomal recessive, non-syndromic enamel malformations in humans and mice. Klk4 ablated mice initially have normal-looking teeth with enamel of full thickness. However, the enamel is soft and protein-rich. Three findings are notable from Klk4 ablated mice: first, enamel rods fall from the interrod enamel leaving behind empty holes where the enamel fractures near the underlying dentin surface. Second, the ~10,000 crystallites that normally fuse to form a solid enamel rod fail to grow together in the ablated mice and can fall out of the rods. Third, and most striking, the crystallites grow substantially in width and thickness (a- and b-axis) in the ablated mice until they almost interlock. The crystallites grow in defined enamel rods, but interlocking is prevented presumably because too much protein remains. Conventional thought holds that enamel proteins bind specifically to the sides of enamel crystals to inhibit growth in width and thickness so that the thin, ribbon-like enamel crystallites grow predominantly in length. Results from Klk4 ablated mice demonstrate that this convention requires updating. An alternative mechanism is proposed whereby enamel proteins serve to form a mold or support structure that shapes and orients the mineral ribbons as they grow in length. The remnants of this support structure must be removed by KLK4 so that the crystallites can interlock to form fully hardened enamel.
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Affiliation(s)
- John D Bartlett
- Harvard School of Dental Medicine Boston, MA ; Department of Mineralized Tissue Biology, The Forsyth Institute Cambridge, MA
| | - James P Simmer
- Department of Biological and Material Sciences, University of Michigan School of Dentistry Ann Arbor, MI, USA
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100
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New insights into the functions of enamel matrices in calcified tissues. JAPANESE DENTAL SCIENCE REVIEW 2014. [DOI: 10.1016/j.jdsr.2014.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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