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Surbek M, Sukseree S, Eckhart L. Iron Metabolism of the Skin: Recycling versus Release. Metabolites 2023; 13:1005. [PMID: 37755285 PMCID: PMC10534741 DOI: 10.3390/metabo13091005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/06/2023] [Accepted: 09/08/2023] [Indexed: 09/28/2023] Open
Abstract
The skin protects the body against exogenous stressors. Its function is partially achieved by the permanent regeneration of the epidermis, which requires high metabolic activity and the shedding of superficial cells, leading to the loss of metabolites. Iron is involved in a plethora of important epidermal processes, including cellular respiration and detoxification of xenobiotics. Likewise, microorganisms on the surface of the skin depend on iron, which is supplied by the turnover of epithelial cells. Here, we review the metabolism of iron in the skin with a particular focus on the fate of iron in epidermal keratinocytes. The iron metabolism of the epidermis is controlled by genes that are differentially expressed in the inner and outer layers of the epidermis, establishing a system that supports the recycling of iron and counteracts the release of iron from the skin surface. Heme oxygenase-1 (HMOX1), ferroportin (SLC40A1) and hephaestin-like 1 (HEPHL1) are constitutively expressed in terminally differentiated keratinocytes and allow the recycling of iron from heme prior to the cornification of keratinocytes. We discuss the evidence for changes in the epidermal iron metabolism in diseases and explore promising topics of future studies of iron-dependent processes in the skin.
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Affiliation(s)
| | | | - Leopold Eckhart
- Department of Dermatology, Medical University of Vienna, 1090 Vienna, Austria; (M.S.); (S.S.)
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2
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Surface and Structural Studies of Age-Related Changes in Dental Enamel: An Animal Model. MATERIALS 2022; 15:ma15113993. [PMID: 35683290 PMCID: PMC9182525 DOI: 10.3390/ma15113993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/26/2022] [Accepted: 06/01/2022] [Indexed: 01/28/2023]
Abstract
In the animal kingdom, continuously erupting incisors provided an attractive model for studying the enamel matrix and mineral composition of teeth during development. Enamel, the hardest mineral tissue in the vertebrates, is a tissue sensitive to external conditions, reflecting various disturbances in its structure. The developing dental enamel was monitored in a series of incisor samples extending the first four weeks of postnatal life in the spiny mouse. The age-dependent changes in enamel surface morphology in the micrometre and nanometre-scale and a qualitative assessment of its mechanical features were examined by applying scanning electron microscopy (SEM) and atomic force microscopy (AFM). At the same time, structural studies using XRD and vibrational spectroscopy made it possible to assess crystallinity and carbonate content in enamel mineral composition. Finally, a model for predicting the maturation based on chemical composition and structural factors was constructed using artificial neural networks (ANNs). The research presented here can extend the existing knowledge by proposing a pattern of enamel development that could be used as a comparative material in environmental, nutritional, and pharmaceutical research.
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Sukseree S, Schwarze UY, Gruber R, Gruber F, Quiles Del Rey M, Mancias JD, Bartlett JD, Tschachler E, Eckhart L. ATG7 is essential for secretion of iron from ameloblasts and normal growth of murine incisors during aging. Autophagy 2020; 16:1851-1857. [PMID: 31880208 DOI: 10.1080/15548627.2019.1709764] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The incisors of rodents comprise an iron-rich enamel and grow throughout adult life, making them unique models of iron metabolism and tissue homeostasis during aging. Here, we deleted Atg7 (autophagy related 7) in murine ameloblasts, i.e. the epithelial cells that produce enamel. The absence of ATG7 blocked the transport of iron from ameloblasts into the maturing enamel, leading to a white instead of yellow surface of maxillary incisors. In aging mice, lack of ATG7 was associated with the growth of ectopic incisors inside severely deformed primordial incisors. These results suggest that 2 characteristic features of rodent incisors, i.e. deposition of iron on the enamel surface and stable growth during aging, depend on autophagic activity in ameloblasts. Abbreviations: ATG5: autophagy related 5; ATG7: autophagy related 7; CMV: cytomegalovirus; Cre: Cre recombinase; CT: computed tomography; FTH1: ferritin heavy polypeptide 1; GFP: green fluorescent protein; KRT5: keratin 5; KRT14: keratin 14; LGALS3: lectin, galactose binding, soluble 3; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; NCOA4: nuclear receptor coactivator 4; NRF2: nuclear factor, erythroid 2 like 2; SQSTM1: sequestosome 1.
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Affiliation(s)
- Supawadee Sukseree
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| | | | - Reinhard Gruber
- Department of Oral Biology, Medical University of Vienna , Vienna, Austria
| | - Florian Gruber
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| | - Maria Quiles Del Rey
- Division of Genomic Stability and DNA Repair, Department of Radiation Oncology, Dana-Farber Cancer Institute , Boston, MA, USA
| | - Joseph D Mancias
- Division of Genomic Stability and DNA Repair, Department of Radiation Oncology, Dana-Farber Cancer Institute , Boston, MA, USA
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State University , Columbus, OH, USA
| | - Erwin Tschachler
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| | - Leopold Eckhart
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
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4
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Houari S, Picard E, Wurtz T, Vennat E, Roubier N, Wu T, Guerquin-Kern J, Duttine M, Thuy T, Berdal A, Babajko S. Disrupted Iron Storage in Dental Fluorosis. J Dent Res 2019; 98:994-1001. [DOI: 10.1177/0022034519855650] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Enamel formation and quality are dependent on environmental conditions, including exposure to fluoride, which is a widespread natural element. Fluoride is routinely used to prevent caries. However, when absorbed in excess, fluoride may also lead to altered enamel structural properties associated with enamel gene expression modulations. As iron plays a determinant role in enamel quality, the aim of our study was to evaluate the iron metabolism in dental epithelial cells and forming enamel of mice exposed to fluoride, as well as its putative relation with enamel mechanical properties. Iron storage was investigated in dental epithelial cells with Perl’s blue staining and secondary ion mass spectrometry imaging. Iron was mainly stored by maturation-stage ameloblasts involved in terminal enamel mineralization. Iron storage was drastically reduced by fluoride. Among the proteins involved in iron metabolism, ferritin heavy chain (Fth), in charge of iron storage, appeared as the preferential target of fluoride according to quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry analyses. Fluorotic enamel presented a decreased quantity of iron oxides attested by electron spin resonance technique, altered mechanical properties measured by nanoindentation, and ultrastructural defects analyzed by scanning electron microscopy and energy dispersive x-ray spectroscopy. The in vivo functional role of Fth was illustrated with Fth+/-mice, which incorporated less iron into their dental epithelium and exhibited poor enamel quality. These data demonstrate that exposure to excessive fluoride decreases ameloblast iron storage, which contributes to the defective structural and mechanical properties in rodent fluorotic enamel. They raise the question of fluoride’s effects on iron storage in other cells and organs that may contribute to its effects on population health.
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Affiliation(s)
- S. Houari
- Centre de Recherche des Cordeliers, INSERM UMRS 1138, Université de Paris, Sorbonne Université, Laboratory of Molecular Oral Pathophysiology, Paris, France
- Garancière Dental Faculty, Université de Paris, Paris, France
| | - E. Picard
- Centre de Recherche des Cordeliers INSERM UMRS 1138 Université de Paris, Sorbonne Université, Physiopathology of Ocular Diseases to Clinical Development, Paris, France
| | - T. Wurtz
- Centre de Recherche des Cordeliers, INSERM UMRS 1138, Université de Paris, Sorbonne Université, Laboratory of Molecular Oral Pathophysiology, Paris, France
| | - E. Vennat
- Laboratory of Mechanics of Soils, Structures and Materials, CNRS, Centrale-Supélec, Université Paris-Saclay, Châtenay-Malabry, France
| | - N. Roubier
- Laboratory of Mechanics of Soils, Structures and Materials, CNRS, Centrale-Supélec, Université Paris-Saclay, Châtenay-Malabry, France
| | - T.D. Wu
- Institut Curie, INSERM U1196, Université Paris-Saclay, Orsay, France
- Université Paris-Sud, Université Paris-Saclay, CNRS UMR 9187, Orsay, France
| | - J.L. Guerquin-Kern
- Institut Curie, INSERM U1196, Université Paris-Saclay, Orsay, France
- Université Paris-Sud, Université Paris-Saclay, CNRS UMR 9187, Orsay, France
| | - M. Duttine
- CNRS UPR 9048, Université de Bordeaux, Institute of Chemistry and Condensed Matter of Bordeaux, Pessac, France
| | - T.T. Thuy
- Faculty of Odonto-stomatology, HochiMinh University of Medicine and Pharmacology, HôchiMinh Ville, Vietnam
| | - A. Berdal
- Centre de Recherche des Cordeliers, INSERM UMRS 1138, Université de Paris, Sorbonne Université, Laboratory of Molecular Oral Pathophysiology, Paris, France
- Garancière Dental Faculty, Université de Paris, Paris, France
- Reference Center for Oral and Dental Rare Diseases, Rothschild Hospital, Paris, France
| | - S. Babajko
- Centre de Recherche des Cordeliers, INSERM UMRS 1138, Université de Paris, Sorbonne Université, Laboratory of Molecular Oral Pathophysiology, Paris, France
- Garancière Dental Faculty, Université de Paris, Paris, France
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5
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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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Interaction between fibronectin and β1 integrin is essential for tooth development. PLoS One 2015; 10:e0121667. [PMID: 25830530 PMCID: PMC4382024 DOI: 10.1371/journal.pone.0121667] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 02/03/2015] [Indexed: 11/19/2022] Open
Abstract
The dental epithelium and extracellular matrix interact to ensure that cell growth and differentiation lead to the formation of teeth of appropriate size and quality. To determine the role of fibronectin in differentiation of the dental epithelium and tooth formation, we analyzed its expression in developing incisors. Fibronectin mRNA was expressed during the presecretory stage in developing dental epithelium, decreased in the secretory and early maturation stages, and then reappeared during the late maturation stage. The binding of dental epithelial cells derived from postnatal day-1 molars to a fibronectin-coated dish was inhibited by the RGD but not RAD peptide, and by a β1 integrin-neutralizing antibody, suggesting that fibronectin-β1 integrin interactions contribute to dental epithelial-cell binding. Because fibronectin and β1 integrin are highly expressed in the dental mesenchyme, it is difficult to determine precisely how their interactions influence dental epithelial differentiation in vivo. Therefore, we analyzed β1 integrin conditional knockout mice (Intβ1lox-/lox-/K14-Cre) and found that they exhibited partial enamel hypoplasia, and delayed eruption of molars and differentiation of ameloblasts, but not of odontoblasts. Furthermore, a cyst-like structure was observed during late ameloblast maturation. Dental epithelial cells from knockout mice did not bind to fibronectin, and induction of ameloblastin expression in these cells by neurotrophic factor-4 was inhibited by treatment with RGD peptide or a fibronectin siRNA, suggesting that the epithelial interaction between fibronectin and β1 integrin is important for ameloblast differentiation and enamel formation.
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7
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Wen X, Paine ML. Iron deposition and ferritin heavy chain (Fth) localization in rodent teeth. BMC Res Notes 2013; 6:1. [PMID: 23281703 PMCID: PMC3556315 DOI: 10.1186/1756-0500-6-1] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 12/18/2012] [Indexed: 05/12/2023] Open
Abstract
Background An iron rich layer on the labial surface is characteristic of the enamel of rodent incisors. In order to address a role for iron content in continuously growing incisors during odontogenesis, we studied iron deposition patterns in enamel and dentine using Perls’ blue staining and ferritin heavy chain (Fth) immunolocalization. Fth expression is regulated by iron level; therefore its localization can be used as a sensitive indicator for iron deposition. Results Sagittal sections of 4-week old rat incisors showed a gradual increase in iron level in the enamel organ from secretory to maturation stages. In addition, iron was detected in ameloblasts of erupting third molars of 4-week old rats, suggesting iron plays a role in both incisor and molar development. In odontoblasts, the presence of iron was demonstrated, and this is consistent with iron’s role in collagen synthesis. Using postnatal 3-, 6-, 9-day old mice, the spatial and temporal expression of Fth in tooth development again indicated the presence of iron in mature ameloblasts and odontoblasts. Conclusions While these data do not explain what functional role iron has in tooth formation, it does highlight a significant molecular activity associated with the formation of the rodent dentition.
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Affiliation(s)
- Xin Wen
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, USA
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8
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Smith CE, Richardson AS, Hu Y, Bartlett JD, Hu JCC, Simmer JP. Effect of kallikrein 4 loss on enamel mineralization: comparison with mice lacking matrix metalloproteinase 20. J Biol Chem 2011; 286:18149-60. [PMID: 21454549 DOI: 10.1074/jbc.m110.194258] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Enamel formation depends on a triad of tissue-specific matrix proteins (amelogenin, ameloblastin, and enamelin) to help initiate and stabilize progressively elongating, thin mineral ribbons of hydroxyapatite formed during an appositional growth phase. Subsequently, these proteins are eradicated to facilitate lateral expansion of the hydroxyapatite crystallites. The purpose of this study was to investigate changes in enamel mineralization occurring in mice unable to produce kallikrein 4 (Klk4), a proteinase associated with terminal extracellular degradation of matrix proteins during the maturation stage. Mice lacking functional matrix metalloproteinase 20 (Mmp20), a proteinase associated with early cleavage of matrix proteins during the secretory stage, were also analyzed as a frame of reference. The results indicated that mice lacking Klk4 produce enamel that is normal in thickness and overall organization in terms of layers and rod/inter-rod structure, but there is a developmental defect in enamel rods where they first form near the dentinoenamel junction. Mineralization is normal up to early maturation after which the enamel both retains and gains additional proteins and is unable to mature beyond 85% mineral by weight. The outmost enamel is hard, but inner regions are soft and contain much more protein than normal. The rate of mineral acquisition overall is lower by 25%. Mice lacking functional Mmp20 produce enamel that is thin and structurally abnormal. Relatively high amounts of protein remain throughout maturation, but the enamel is able to change from 67 to 75% mineral by weight during maturation. These findings reaffirm the importance of secreted proteinases to enamel mineral acquisition.
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Affiliation(s)
- Charles E Smith
- Facility for Electron Microscopy Research, Department of Anatomy and Cell Biology and Faculty of Dentistry, McGill University, Montreal, Quebec H3A 2B2, Canada.
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Nishikawa S. Transient increase in anti-p-ATF2 immunoreactivity in the late secretion ameloblasts apical to the transition zone of rat incisors. Anat Sci Int 2004; 79:87-94. [PMID: 15218628 DOI: 10.1111/j.1447-073x.2004.00073.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Activating transcription factor 2 (ATF2) was localized in the ameloblasts of rat incisors by immunohistochemistry. A specific antibody against phosphorylated ATF2 (p-ATF2), which is an activated form of ATF2, was detected from the proliferation zone to maturation ameloblasts just after the transition. In the secretion zone, a transient increase in p-ATF2 was observed in the late secretion ameloblast nuclei, where a stronger reactivity of p-ATF2 extended from 1 mm apical to the transition to the transition zone, whereas ameloblast nuclei in most of the maturation zone exhibited either weak or no reactivity. A similar pattern was also observed in the case of c-Jun immunohistochemistry, except for in most of the maturation zone, where strong c-Jun reactivity was detected. Thus, ATF-2 and c-Jun are deeply involved in amelogenesis and, in particular, ATF2 is related to the proliferation, differentiation, secretion and transition zones.
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Affiliation(s)
- Sumio Nishikawa
- Department of Biology, Tsururmi University School of Dental Medicine, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan.
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Yanagawa T, Itoh K, Uwayama J, Shibata Y, Yamaguchi A, Sano T, Ishii T, Yoshida H, Yamamoto M. Nrf2 deficiency causes tooth decolourization due to iron transport disorder in enamel organ. Genes Cells 2004; 9:641-51. [PMID: 15265007 DOI: 10.1111/j.1356-9597.2004.00753.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Rodents have brownish-yellow incisors whose colour represents their iron content. Iron is deposited into the mature enamel by ameloblasts that outline enamel surface of the teeth. Nrf2 is a basic region-leucine zipper type transcription factor that regulates expression of a range of cytoprotective genes in response to oxidative and xenobiotic stresses. We found that genetically engineered Nrf2-deficient mice show decolourization of the incisors. While incisors of wild-type mice were brownish yellow, incisors of Nrf2-deficient mice were greyish white in colour. Micro X-ray imaging analysis revealed that the iron content in Nrf2-deficient mouse incisors were significantly decreased compared to that of wild-type mice. We found that iron was aberrantly deposited in the papillary layer cells of enamel organ in Nrf2-deficient mouse, suggesting that the iron transport from blood vessels to ameloblasts was disturbed. We also found that ameloblasts of Nrf2-null mouse show degenerative atrophy at the late maturation stage, which gives rise to the loss of iron deposition to the surface of mature enamel. Our results thus demonstrate that the enamel organ of Nrf2-deficient mouse has a reduced iron transport capacity, which results in both the enamel cell degeneration and disturbance of iron deposition on to the enamel surface.
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Affiliation(s)
- Toru Yanagawa
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba 305-8577, Japan
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Fukumoto E, Sakai H, Fukumoto S, Yagi T, Takagi O, Kato Y. Cadherin-related neuronal receptors in incisor development. J Dent Res 2003; 82:17-22. [PMID: 12508039 DOI: 10.1177/154405910308200105] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Cadherins are cell adhesion molecules that are critical for tissue development. In this report, we identified members of the cadherin family cadherin-related neuronal receptors (CNRs) 1 and 5 expressed in rat incisors by the differential display method. Quantitative RT-PCR revealed that CNR1 mRNA is expressed in the secretory stage but reduced in the early-maturation stage, while CNR5 mRNA is expressed in both these stages. In situ hybridization showed that strong expression of CNR1 is strong in the secretory stage, but reduced in the early phase and diminished in the late phase of the early-maturation stage. CNR5 mRNA is expressed almost at the same levels in the secretory and in the early phase of the early-maturation stages but is absent in the late phase of the early-maturation stage. Both CNR1 and 5 mRNA are continuously expressed in odontoblasts. Immunohistology showed that CNR proteins are expressed in the secretory and early-maturation stages of ameloblasts, but no protein expression at the late-maturation stage was observed. CNR proteins were continuously expressed in odontoblasts. We found that recombinant CNR1 binds dental epithelial and mesenchymal cells through N-terminal domain EC1 in vitro. These results suggest that CNR1 and CNR5 may play an important role in enamel and dentin formation, probably through cell-cell and/or cell-matrix interactions.
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Affiliation(s)
- E Fukumoto
- Department of Preventive Dentistry, Nagasaki School of Dentistry, Japan.
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12
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Morohashi T, Hirama Y, Takahara S, Sano T, Saitoh S, Ohta A, Sasa R, Yamada S. Defects in mandibular bone area, enamel iron content and dentine formation following gastrectomy in rats. Arch Oral Biol 2002; 47:499-504. [PMID: 12102767 DOI: 10.1016/s0003-9969(02)00016-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fourteen 5-week-old male Sprague-Dawley rats were equally divided into two groups, sham-operated and gastrectomized. Tetracycline and calcein were given to label dentine. Four weeks after surgery, blood was collected for measurement of serum iron, calcium and parathyroid hormone (PTH) and the mandibles and maxillae were then removed. Sagittal sections of the maxilla or cross-sections of the mandible were prepared and examined. Backscattered electron images of the maxilla were taken and the iron content at the neck of incisors was measured by energy-dispersive X-ray. The dentine apposition rate in maxillary incisors was measured by fluorescence microscopy. Serum iron was significantly decreased, while PTH was significantly elevated without any change in the serum calcium in gastrectomized rats. Gastrectomy caused a gross loss of iron content in superficial enamel. The dentine apposition rate was significantly reduced by 30%. Both cortical and cancellous bone in the mandibula were significantly reduced. However, the total bone area in gastrectomized rats was similar to that in sham-operated rats. These results suggest that bone resorption was enhanced and dentine formation was reduced after gastrectomy.
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Affiliation(s)
- Tomio Morohashi
- Department of Pharmacology, School of Dentistry, Showa University, Hatanodai 1-5-8, Shinagawa-ku, Tokyo 142-8555, Japan.
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13
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Kobayashi Y, Hashimoto F, Miyamoto H, Kanaoka K, Miyazaki-Kawashita Y, Nakashima T, Shibata M, Kobayashi K, Kato Y, Sakai H. Force-induced osteoclast apoptosis in vivo is accompanied by elevation in transforming growth factor beta and osteoprotegerin expression. J Bone Miner Res 2000; 15:1924-34. [PMID: 11028444 DOI: 10.1359/jbmr.2000.15.10.1924] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The mechanism controlling the disappearance of osteoclasts from bone surfaces after bone resorption in vivo is largely unknown. This is because there is no suitable experimental system to trace the final fate of osteoclasts. Here, we used an experimental model of tooth movement in rats to show that preexisting osteoclasts disappeared from the bone surface through apoptosis during a force-induced rapid shift from bone resorption to formation. On the distal alveolar bone surface of the maxillary molar in growing rats, many mature osteoclasts were present. When light tensional force was applied to the bone surface through an orthodontic appliance, these preexisting osteoclasts gradually disappeared. One day after the application of force, about 24% of the osteoclasts exhibited apoptotic morphology and the proportion of apoptotic cells was increased to 41% by day 2, then decreased afterward. These changes were undetectable on the control distal alveolar bone surface, which is free from tensional force. As shown by in situ hybridization, a marked increase in transforming growth factor beta1 (TGF-beta1) and osteoprotegerin (OPG) messenger RNA (mRNA) was observed in the stretched cells on the tensioned distal bone surface, simultaneously with the loss of osteoclasts. Both of these factors are known to have a negative effect on osteoclast recruitment and survival. As early as 2 days after force application, some of these stretched cells were identified as cuboidal osteoblasts showing intense signals for both factors. Our data suggest there may be a sequential link in tensional force applied on the bone lining cells, up-regulation of TGF-beta1/OPG, and disappearance of osteoclasts.
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Affiliation(s)
- Y Kobayashi
- Department of Orthodontics, Nagasaki University School of Dentistry, Sakamoto, Japan
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14
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Cheng Q, Gonzalez P, Zigler JS. High level of ferritin light chain mRNA in lens. Biochem Biophys Res Commun 2000; 270:349-55. [PMID: 10753629 DOI: 10.1006/bbrc.2000.2425] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ferritin is of particular interest with regard to cataract because (i) cataract occurs in individuals with hereditary hyperferritinemia cataract syndrome (HHCS), a condition in which ferritin light chain (L-ferritin) protein is overexpressed systemically, and (ii) ferritin is an important regulator of oxidative stress, a primary factor in the etiology of aging-related cataract. From gene array analysis two novel observations were made with respect to ferritin gene expression: first, lenses from guinea pigs and humans have disproportionately high levels of L-ferritin mRNA relative to the amounts of ferritin protein present, and second, L-ferritin message increased markedly in lenses from guinea pigs with hereditary nuclear cataract. The human lens L-ferritin sequence was identical to previous data from human liver; the guinea pig sequence was 86% identical to the human sequence at the amino acid level. Despite mRNA levels similar to those of major lens crystallins, lens ferritin was undetectable by Western blot techniques.
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Affiliation(s)
- Q Cheng
- Laboratory of Mechanisms of Ocular Diseases, National Eye Institute, Bethesda, Maryland 20892, USA
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