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Abramyan J, Geetha-Loganathan P, Šulcová M, Buchtová M. Role of Cell Death in Cellular Processes During Odontogenesis. Front Cell Dev Biol 2021; 9:671475. [PMID: 34222243 PMCID: PMC8250436 DOI: 10.3389/fcell.2021.671475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/24/2021] [Indexed: 01/20/2023] Open
Abstract
The development of a tooth germ in a precise size, shape, and position in the jaw, involves meticulous regulation of cell proliferation and cell death. Apoptosis, as the most common type of programmed cell death during embryonic development, plays a number of key roles during odontogenesis, ranging from the budding of the oral epithelium during tooth initiation, to later tooth germ morphogenesis and removal of enamel knot signaling center. Here, we summarize recent knowledge about the distribution and function of apoptotic cells during odontogenesis in several vertebrate lineages, with a special focus on amniotes (mammals and reptiles). We discuss the regulatory roles that apoptosis plays on various cellular processes during odontogenesis. We also review apoptosis-associated molecular signaling during tooth development, including its relationship with the autophagic pathway. Lastly, we cover apoptotic pathway disruption, and alterations in apoptotic cell distribution in transgenic mouse models. These studies foster a deeper understanding how apoptotic cells affect cellular processes during normal odontogenesis, and how they contribute to dental disorders, which could lead to new avenues of treatment in the future.
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Affiliation(s)
- John Abramyan
- Department of Natural Sciences, University of Michigan–Dearborn, Dearborn, MI, United States
| | | | - Marie Šulcová
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
- Laboratory of Molecular Morphogenesis, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Brno, Czechia
| | - Marcela Buchtová
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
- Laboratory of Molecular Morphogenesis, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Brno, Czechia
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Nakatsugawa K, Kurosaka H, Inubushi T, Aoyama G, Isogai Y, Usami Y, Toyosawa S, Yamashiro T. Stage- and tissue-specific effect of cyclophosphamide during tooth development. Eur J Orthod 2019; 41:519-530. [PMID: 30715254 DOI: 10.1093/ejo/cjz002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The aim of this study was to investigate the toxic effect of cyclophosphamide (CPA) in the development of rodent molars. METHODS CPA was administered intraperitoneally in postnatal mice between Day 1 and Day 10, and the morphological phenotype was evaluated at Day 26 using micro-computed tomography and histological analysis, including cell proliferation and cell death analyses. RESULTS M3 molars of the mice who received 100 mg/kg CPA treatment at Day 6 or M2 molars who received treatment at Day 1 resulted in tooth agenesis or marked hypoplasia. Histological observation demonstrated that CPA treatment at Day 6 resulted in shrinkage of the M3 tooth germs, with a significant reduction in the proliferation of apoptotic cells. Conversely, CPA exposure at Day 2, which occurs at around the bud stage of M3, resulted in crown and root hypoplasia, with reduced numbers of cusp and root. In addition, CPA exposure at Day 10, which is the late bell stage of M3, induced root shortening; however, it did not affect crown morphogenesis. LIMITATIONS The timing of CPA administration is limited to after birth. Therefore, its effect during the early stages of M1 and M2 could not be investigated. CONCLUSION Defective phenotypes were evident in both crown and roots due to the effect of CPA. Interestingly, the severity of the phenotypes was associated with the developmental stages of the tooth germs at the time of CPA administration. The cap/early bell stage is the most susceptive timing for tooth agenesis, whereas the late bell stage is predominantly affected in terms of root formation by CPA administration.
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Affiliation(s)
- Kohei Nakatsugawa
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Hiroshi Kurosaka
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Toshihiro Inubushi
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Gozo Aoyama
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Yukako Isogai
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Yu Usami
- Department of Oral Pathology, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Satoru Toyosawa
- Department of Oral Pathology, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Takashi Yamashiro
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Osaka, Japan
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Hasegawa K, Wada H, Nagata K, Fujiwara H, Wada N, Someya H, Mikami Y, Sakai H, Kiyoshima T. Facioscapulohumeral muscular dystrophy (FSHD) region gene 1 (FRG1) expression and possible function in mouse tooth germ development. J Mol Histol 2016; 47:375-87. [PMID: 27234941 DOI: 10.1007/s10735-016-9680-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/18/2016] [Indexed: 01/01/2023]
Abstract
Abnormal expression of Facioscapulohumeral muscular dystrophy (FSHD) region gene 1 (FRG1) is involved in the pathogenesis of FSHD. FRG1 is also important for the normal muscular and vascular development. Our previous study showed that FRG1 is one of the highly expressed genes in the mandible on embryonic day 10.5 (E10.5) than on E12.0. In this study, we investigated the temporospatial expression pattern of FRG1 mRNA and protein during the development of the mouse lower first molar, and also evaluated the subcellular localization of the FRG1 protein in mouse dental epithelial (mDE6) cells. The FRG1 expression was identified in the dental epithelial and mesenchymal cells at the initiation and bud stages. It was detected in the inner enamel epithelium at the cap and early bell stages. At the late bell and root formation stages, these signals were detected in ameloblasts and odontoblasts during the formation of enamel and dentin matrices, respectively. The FRG1 protein was localized in the cytoplasm in the mouse tooth germ in vivo, while FRG1 was detected predominantly in the nucleus and faintly in the cytoplasm in mDE6 cells in vitro. In mDE6 cells treated with bone morphogenetic protein 4 (BMP4), the protein expression of FRG1 increased in cytoplasm, suggesting that FRG1 may translocate to the cytoplasm. These findings suggest that FRG1 is involved in the morphogenesis of the tooth germ, as well as in the formation of enamel and dentin matrices and that FRG1 may play a role in the odontogenesis in the mouse following BMP4 stimulation.
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Affiliation(s)
- Kana Hasegawa
- Laboratory of Oral Pathology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.,Department of Endodontology and Operative Dentistry, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Hiroko Wada
- Laboratory of Oral Pathology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
| | - Kengo Nagata
- Laboratory of Oral Pathology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Hiroaki Fujiwara
- Laboratory of Oral Pathology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Naohisa Wada
- Division of General Dentistry, Kyushu University Hospital, Kyushu University, Fukuoka, Japan
| | - Hirotaka Someya
- Section of Implant and Rehabilitative Dentistry, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Yurie Mikami
- Laboratory of Oral Pathology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.,Section of Oral and Maxillofacial Oncology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Hidetaka Sakai
- Laboratory of Oral Pathology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Tamotsu Kiyoshima
- Laboratory of Oral Pathology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
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Liu M, Zhao S, Wang XP. YAP Overexpression Affects Tooth Morphogenesis and Enamel Knot Patterning. J Dent Res 2014; 93:469-74. [DOI: 10.1177/0022034514525784] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Teeth develop through distinct morphological stages. At the cap stage, a compactly clustered and concentrically arranged cell mass, the enamel knot, appears at the tip of the enamel organ. Cells in this knot express sets of key molecules, and as such have been proposed to act as a signaling center directing tooth morphogenesis and tooth cusp formation. YAP is a transcriptional co-activator of the Hippo signaling pathway that is essential for the proper regulation of organ growth. In this study, we analyzed the tooth phenotype in transgenic mice that overexpressed a constitutively active form of YAP in the dental epithelium. We found that overexpression of YAP resulted in deformed tooth morphogenesis with widened dental lamina. In addition, the enamel knot was mislocated to the upper portion of the enamel organ, where it remained devoid of proliferating cells and contained apoptotic cells with intense Edar transcripts and reduced E-cadherin expression. Interestingly, some signaling molecules, such as Shh, Fgf4, and Wnt10a, were not expressed in this mislocated enamel knot, but remained at the tip of the enamel organ. Analysis of these data suggests that the signaling center is induced by reciprocal epithelial-mesenchymal interactions, and its induction may be independent of the enamel knot.
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Affiliation(s)
- M. Liu
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - S. Zhao
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
- Department of Pediatric Dentistry, School of Stomatology, Peking University, Beijing 100081, China
| | - X.-P. Wang
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
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Lesot H, Hovorakova M, Peterka M, Peterkova R. Three-dimensional analysis of molar development in the mouse from the cap to bell stage. Aust Dent J 2014; 59 Suppl 1:81-100. [DOI: 10.1111/adj.12132] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- H Lesot
- Institut National de la Santé et de la Recherche Médicale; UMR 1109, Team ‘Osteoarticular and Dental Regenerative NanoMedicine’; Strasbourg France
- Université de Strasbourg; Faculté de Chirurgie Dentaire; Strasbourg France
| | - M Hovorakova
- Department of Teratology; Institute of Experimental Medicine, Academy of Sciences of the Czech Republic; Prague Czech Republic
| | - M Peterka
- Department of Teratology; Institute of Experimental Medicine, Academy of Sciences of the Czech Republic; Prague Czech Republic
| | - R Peterkova
- Department of Teratology; Institute of Experimental Medicine, Academy of Sciences of the Czech Republic; Prague Czech Republic
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Sohn WJ, Choi MA, Yamamoto H, Lee S, Lee Y, Jung JK, Jin MU, An CH, Jung HS, Suh JY, Shin HI, Kim JY. Contribution of mesenchymal proliferation in tooth root morphogenesis. J Dent Res 2013; 93:78-83. [PMID: 24155265 DOI: 10.1177/0022034513511247] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In mouse tooth development, the roots of the first lower molar develop after crown formation to form 2 cylindrical roots by post-natal day 5. This study compared the morphogenesis and cellular events of the mesial-root-forming (MRF) and bifurcation-forming (BF) regions, located in the mesial and center of the first lower molar, to better define the developmental mechanisms involved in multi-rooted tooth formation. We found that the mesenchyme in the MRF showed relatively higher proliferation than the bifurcation region. This suggested that spatially regulated mesenchymal proliferation is required for creating cylindrical root structure. The mechanism may involve the mesenchyme forming a physical barrier to epithelial invagination of Hertwig's epithelial root sheath. To test these ideas, we cultured roots in the presence of pharmacological inhibitors of microtubule and actin polymerization, nocodazole and cytochalasin-D. Cytochalasin D also inhibits proliferation in epithelium and mesenchyme. Both drugs resulted in altered morphological changes in the tooth root structures. In particular, the nocodazole- and cytochalasin-D-treated specimens showed a loss of root diameter and formation of a single-root, respectively. Immunolocalization and three-dimensional reconstruction results confirmed these mesenchymal cellular events, with higher proliferation in MRF in multi-rooted tooth formation.
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Affiliation(s)
- W-J Sohn
- Department of Biochemistry, School of Dentistry, IHBR, Kyungpook National University, Daegu, Korea
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Lagronova-Churava S, Spoutil F, Vojtechova S, Lesot H, Peterka M, Klein OD, Peterkova R. The dynamics of supernumerary tooth development are differentially regulated by Sprouty genes. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2013; 320:307-20. [PMID: 23606267 DOI: 10.1002/jez.b.22502] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 02/28/2013] [Accepted: 03/01/2013] [Indexed: 11/10/2022]
Abstract
In mice, a toothless diastema separates the single incisor from the three molars in each dental quadrant. In the prospective diastema of the embryo, small rudimentary buds are found that are presumed to be rudiments of suppressed teeth. A supernumerary tooth occurs in the diastema of adult mice carrying mutations in either Spry2 or Spry4. In the case of Spry2 mutants, the origin of the supernumerary tooth involves the revitalization of a rudimentary tooth bud (called R2), whereas its origin in the Spry4 mutants is not known. In addition to R2, another rudimentary primordium (called MS) arises more anteriorly in the prospective diastema. We investigated the participation of both rudiments (MS and R2) in supernumerary tooth development in Spry2 and Spry4 mutants by comparing morphogenesis, proliferation, apoptosis, size and Shh expression in the dental epithelium of MS and R2 rudiments. Increased proliferation and decreased apoptosis were found in MS and R2 at embryonic day (ED) 12.5 and 13.5 in Spry2(-/-) embryos. Apoptosis was also decreased in both rudiments in Spry4(-/-) embryos, but the proliferation was lower (similar to WT mice), and supernumerary tooth development was accelerated, exhibiting a cap stage by ED13.5. Compared to Spry2(-/-) mice, a high number of Spry4(-/-) supernumerary tooth primordia degenerated after ED13.5, resulting in a low percentage of supernumerary teeth in adults. We propose that Sprouty genes were implicated during evolution in reduction of the cheek teeth in Muridae, and their deletion can reveal ancestral stages of murine dental evolution.
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Ishikawa Y, Ida-Yonemochi H, Nakakura-Ohshima K, Ohshima H. The relationship between cell proliferation and differentiation and mapping of putative dental pulp stem/progenitor cells during mouse molar development by chasing BrdU-labeling. Cell Tissue Res 2012; 348:95-107. [DOI: 10.1007/s00441-012-1347-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 01/19/2012] [Indexed: 02/06/2023]
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Ida-Yonemochi H, Nakatomi M, Harada H, Takata H, Baba O, Ohshima H. Glucose uptake mediated by glucose transporter 1 is essential for early tooth morphogenesis and size determination of murine molars. Dev Biol 2011; 363:52-61. [PMID: 22226978 DOI: 10.1016/j.ydbio.2011.12.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 11/11/2011] [Accepted: 12/12/2011] [Indexed: 11/25/2022]
Abstract
Glucose is an essential source of energy for body metabolism and is transported into cells by glucose transporters (GLUTs). Well-characterized class I GLUT is subdivided into GLUTs1-4, which are selectively expressed depending on tissue glucose requirements. However, there is no available data on the role of GLUTs during tooth development. This study aims to clarify the functional significance of class I GLUT during murine tooth development using immunohistochemistry and an in vitro organ culture experiment with an inhibitor of GLUTs1/2, phloretin, and Glut1 and Glut2 short interfering RNA (siRNA). An intense GLUT1-immunoreaction was localized in the enamel organ of bud-stage molar tooth germs, where the active cell proliferation occurred. By the bell stage, the expression of GLUT1 in the dental epithelium was dramatically decreased in intensity, and subsequently began to appear in the stratum intermedium at the late bell stage. On the other hand, GLUT2-immunoreactivity was weakly observed in the whole tooth germs throughout all stages. The inhibition of GLUTs1/2 by phloretin in the bud-stage tooth germs induced the disturbance of primary enamel knot formation, resulting in the developmental arrest of the explants and the squamous metaplasia of dental epithelial cells. Furthermore, the inhibition of GLUTs1/2 in cap-to-bell-stage tooth germs reduced tooth size in a dose dependent manner. These findings suggest that the expression of GLUT1 and GLUT2 in the dental epithelial and mesenchymal cells seems to be precisely and spatiotemporally controlled, and the glucose uptake mediated by GLUT1 plays a crucial role in the early tooth morphogenesis and tooth size determination.
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Affiliation(s)
- Hiroko Ida-Yonemochi
- Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8514, Japan
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Mammoto T, Mammoto A, Torisawa YS, Tat T, Gibbs A, Derda R, Mannix R, de Bruijn M, Yung CW, Huh D, Ingber DE. Mechanochemical control of mesenchymal condensation and embryonic tooth organ formation. Dev Cell 2011; 21:758-69. [PMID: 21924961 DOI: 10.1016/j.devcel.2011.07.006] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 05/28/2011] [Accepted: 07/11/2011] [Indexed: 12/24/2022]
Abstract
Mesenchymal condensation is critical for organogenesis, yet little is known about how this process is controlled. Here we show that Fgf8 and Sema3f, produced by early dental epithelium, respectively, attract and repulse mesenchymal cells, which cause them to pack tightly together during mouse tooth development. Resulting mechanical compaction-induced changes in cell shape induce odontogenic transcription factors (Pax9, Msx1) and a chemical cue (BMP4), and mechanical compression of mesenchyme is sufficient to induce tooth-specific cell fate switching. The inductive effects of cell compaction are mediated by suppression of the mechanical signaling molecule RhoA, and its overexpression prevents odontogenic induction. Thus, the mesenchymal condensation that drives tooth formation is induced by antagonistic epithelial morphogens that manifest their pattern-generating actions mechanically via changes in mesenchymal cell shape and altered mechanotransduction.
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Affiliation(s)
- Tadanori Mammoto
- Vascular Biology Program, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
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Honda JY, Kobayashi I, Kiyoshima T, Nagata K, Wada H, Ookuma Y, Fujiwara H, Shiotsuka M, Takahashi I, Sakai H. In situ expression of the mitochondrial ATPase6 gene in the developing tooth germ of the mouse lower first molar. J Mol Histol 2011; 42:83-90. [DOI: 10.1007/s10735-010-9309-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 12/24/2010] [Indexed: 01/15/2023]
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Štembírek J, Buchtová M, Král T, Matalová E, Lozanoff S, Míšek I. Early morphogenesis of heterodont dentition in minipigs. Eur J Oral Sci 2010; 118:547-58. [DOI: 10.1111/j.1600-0722.2010.00772.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Spatial and temporal distribution of Ki-67 proliferation marker, Bcl-2 and Bax proteins in the developing human tooth. Arch Oral Biol 2010; 55:1007-16. [PMID: 20732674 DOI: 10.1016/j.archoralbio.2010.07.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 07/30/2010] [Accepted: 07/30/2010] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To investigate the spatial and temporal expression of proliferation Ki-67 marker, pro-apoptotic Bax and anti-apoptotic Bcl-2 proteins during early development of the human tooth. MATERIALS AND METHODS Histological sections of eight human conceptuses, 5-10 postovulatory weeks old, were used for immunolocalization for Ki-67, Bax and Bcl-2 markers. Quantification was performed by calculating the fraction of Ki-67 positive cells, expressed as a mean ± SD, and analysed by Mann-Whitney test, Kruskal-Wallis and Dunn's post hoc test. RESULTS In 6th-7th developmental weeks, the tooth germ and dental crest contained 37% of proliferating cells, which increased to 40% in the 8th week, and then decreased to 15% in the 10th week, whilst the proliferation in the ectomesenchyme subsequently dropped from 37% to 23%. Epithelial parts of the enamel organ displayed similar proliferation activity (31-36%), dental crest 10%, whilst enamel knot showed no proliferating activity. The tooth ectomesenchyme contained more proliferating cells (50%) than the jaw ectomesenchyme (35%), and both dropped to 28% in the 10th week. Ectomesenchyme between the tooth germs contained 23%, whilst the jaw ectomesenchyme contained 15% of proliferating cells. Bcl-2 expression had following pattern: strong in proliferating cells, moderate in tooth germs and dental crest, and weak in the ectomesenchyme. Bax co-expressed with Bcl-2 in the tooth germ and dental crest. In the reticulum and inner enamel epithelium Bcl-2 had prevalent expression, whilst Bax prevailed in the outer enamel epithelium and tooth ectomesenchyme. CONCLUSIONS Proliferating cells most likely influence growth of the tooth germ, Bcl-2 affects proliferation and differentiation of specific cell lineages, whilst Bax influences process of cell death.
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In situ expression of 15 kDa interferon alpha responsive gene in the developing tooth germ of the mouse lower first molar. J Mol Histol 2010; 41:185-91. [DOI: 10.1007/s10735-010-9277-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2010] [Accepted: 07/02/2010] [Indexed: 12/18/2022]
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Xie M, Kobayashi I, Kiyoshima T, Nagata K, Ookuma Y, Fujiwara H, Sakai H. In situ expression of ribosomal protein L21 in developing tooth germ of the mouse lower first molar. J Mol Histol 2009; 40:361-7. [PMID: 20043235 DOI: 10.1007/s10735-009-9249-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 12/15/2009] [Indexed: 11/28/2022]
Abstract
We previously performed cDNA subtraction between the mouse mandibles at embryonic day 10.5 (E10.5) in the pre-initiation stage of the odontogenesis and E12.0 in the late initiation stage to investigate the key regulator genes in odontogenesis. Ribosomal protein L21 (Rpl21) is one of differentially expressed genes in the E12.0 mandible. This study examined the precise expression pattern of Rpl21 mRNA in the mouse mandibular first molar by in situ hybridization. Rpl21 mRNA was expressed in the presumptive dental epithelium and the underlying mesenchyme at E10.5, and in the thickened dental epithelium at E12.0. Strong in situ signals were observed in the epithelial bud at E14.0, and in the enamel organ at E15.0. However, either no (E14.0) or only a weak (E15.0) in situ signal was found in the primary enamel knot at these gestational days. Rpl21 was strongly expressed in the inner enamel epithelium, cervical loop and dental lamina from E16.0 to E18.0. In addition, Rpl21 mRNA was also demonstrated in various developing cranio-facial organs. These results suggest that Rpl21 participates in the synthesis of various polypeptides which might be related to the initiation and the development of such tooth germ, and also in the synthesis of enamel components in the presecretory stage of the ameloblast. Rpl21 for protein synthesis might also be related to the morphogenesis of the developing cranio-facial organs.
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Affiliation(s)
- Ming Xie
- Laboratory of Oral Pathology and Medicine, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Etokebe GE, Küchler AM, Haraldsen G, Landin M, Osmundsen H, Dembic Z. Family-with-sequence-similarity-46, member A (Fam46a) gene is expressed in developing tooth buds. Arch Oral Biol 2009; 54:1002-7. [PMID: 19740458 DOI: 10.1016/j.archoralbio.2009.08.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 08/12/2009] [Accepted: 08/16/2009] [Indexed: 01/25/2023]
Abstract
OBJECTIVE In search for possible novel genes that may be involved in tooth development, we analysed the genome-wide transcriptome of developing mandibular tooth germs of mouse during embryonic and early life and selected family-with-sequence-similarity-46, member A (Fam46a) gene for further expression analysis. METHODS We applied microarray, quantitative real time polymerase chain reaction and in situ hybridisation methods for the expression study of the mouse Fam46a gene. RESULTS We found the family-with-sequence-similarity-46, member A (Fam46a) gene to be highly expressed and further verify its temporo-spatial expression in the mouse tooth. CONCLUSION We have shown that Fam46a is expressed in ameloblasts' nuclei of tooth germs and hypothesise that it might act together with morphogenetic factors important for the formation of enamel in mouse tooth.
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Affiliation(s)
- Godfrey E Etokebe
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Norway.
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Smith MM, Fraser GJ, Mitsiadis TA. Dental lamina as source of odontogenic stem cells: evolutionary origins and developmental control of tooth generation in gnathostomes. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2009; 312B:260-80. [PMID: 19156674 DOI: 10.1002/jez.b.21272] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This study considers stem cells for odontogenic capability in biological tooth renewal in the broad context of gnathostome dentitions and the derivation of them from oral epithelium. The location of the developmental site and cell dynamics of the dental lamina are parameters of a possible source for odontogenic epithelial stem cells, but the phylogenetic history is not known. Understanding the phylogenetic basis for stem cell origins throughout continuous tooth renewal in basal jawed vertebrates is the ultimate objective of this study. The key to understanding the origin and location of stem cells in the development of the dentition is sequestration of stem cells locally for programmed tooth renewal. We suggest not only the initial pattern differences in each dentate field but local control subsequently for tooth renewal within each family. The role of the specialized odontogenic epithelium (odontogenic band) is considered as that in which the stem cells reside and become partitioned. These regulate time, position and shape in sequential tooth production. New histological data for chondrichthyan fish show first a thickening of the oral epithelium (odontogenic band). After this, all primary and successive teeth are only generated deep to the oral epithelium from a dental lamina. In contrast, in osteichthyan fish the first teeth develop directly within the odontogenic band. In addition, successors are initiated at each tooth site in the predecessor tooth germ (without a dental lamina). We suggest that stem cells specified for each tooth family are set up and located in intermediate cells between the outer and inner dental epithelia.
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Nait Lechguer A, Kuchler-Bopp S, Lesot H. Crown formation during tooth development and tissue engineering. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2009; 312B:399-407. [PMID: 19132735 DOI: 10.1002/jez.b.21256] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Considering tooth crown engineering, three main parameters have to be taken into account: (1) the relationship between crown morphology and tooth functionality, (2) the growth of the organ, which is hardly compatible with the use of preformed scaffolds, and (3) the need for easily available nondental competent cell sources. In vitro reassociation experiments using either dental tissues or bone marrow-derived cells (BMDC) have been designed to get information about the mechanisms to be preserved in order to allow crown engineering. As the primary enamel knot (PEK) is involved in signaling crown morphogenesis, the formation and fate of this structure was investigated (1) in heterotopic reassociations between embryonic day 14 (ED14) incisor and molar enamel organs and mesenchymes, and (2) in reassociations between ED14 molar enamel organs and BMDC. A PEK formed in cultured heterotopic dental tissue reassociations. The mesenchyme controls the fate of the EK cells, incisor or molar-specific using apoptosis as criterion, and functionality to drive single/multiple cusps tooth development. Although previous investigations showed that they might differentiate as odontoblast- or ameloblast-like cells, BMDC reassociated to an enamel organ could not support the development of multicusp teeth. These cells apparently could neither maintain nor stimulate the formation of a PEK.
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Lee DS, Park JT, Kim HM, Ko JS, Son HH, Gronostajski RM, Cho MI, Choung PH, Park JC. Nuclear factor I-C is essential for odontogenic cell proliferation and odontoblast differentiation during tooth root development. J Biol Chem 2009; 284:17293-17303. [PMID: 19386589 DOI: 10.1074/jbc.m109.009084] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Our previous studies have demonstrated that nuclear factor I-C (NFI-C) null mice developed short molar roots that contain aberrant odontoblasts and abnormal dentin formation. Based on these findings, we performed studies to elucidate the function of NFI-C in odontoblasts. Initial studies demonstrated that aberrant odontoblasts become dissociated and trapped in an osteodentin-like mineralized tissue. Abnormal odontoblasts exhibit strong bone sialoprotein expression but a decreased level of dentin sialophosphoprotein expression when compared with wild type odontoblasts. Loss of Nfic results in an increase in p-Smad2/3 expression in aberrant odontoblasts and pulp cells in the subodontoblastic layer in vivo and primary pulp cells from Nfic-deficient mice in vitro. Cell proliferation analysis of both cervical loop and ectomesenchymal cells of the Nfic-deficient mice revealed significantly decreased proliferative activity compared with wild type mice. In addition, Nfic-deficient primary pulp cells showed increased expression of p21 and p16 but decreased expression of cyclin D1 and cyclin B1, strongly suggesting cell growth arrest caused by a lack of Nfic activity. Analysis of the pulp and abnormal dentin in Nfic-deficient mice revealed an increase in apoptotic activity. Further, Nfic-deficient primary pulp cells exhibited an increase in caspase-8 and -3 activation, whereas the cleaved form of Bid was hardly detected. These results indicate that the loss of Nfic leads to the suppression of odontogenic cell proliferation and differentiation and induces apoptosis of aberrant odontoblasts during root formation, thereby contributing to the formation of short roots.
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Affiliation(s)
- Dong-Seol Lee
- From the Department of Oral Histology-Developmental Biology, Dental Research Institute, Seoul 110-749, Korea
| | - Jong-Tae Park
- From the Department of Oral Histology-Developmental Biology, Dental Research Institute, Seoul 110-749, Korea
| | - Hyun-Man Kim
- From the Department of Oral Histology-Developmental Biology, Dental Research Institute, Seoul 110-749, Korea
| | - Jea Seung Ko
- From the Department of Oral Histology-Developmental Biology, Dental Research Institute, Seoul 110-749, Korea
| | - Ho-Hyun Son
- Conservative Dentistry, Seoul 110-749, Korea
| | - Richard M Gronostajski
- Department of Biochemistry and the Program in Neuroscience, School of Medicine and Biomedical Science, Buffalo, New York 14214-3092
| | - Moon-Il Cho
- Department of Oral Biology, School of Dental Medicine, State University of New York at Buffalo, Buffalo, New York 14214-3092
| | - Pill-Hoon Choung
- Oral & Maxillofacial Surgery, Seoul 110-749, Korea; Tooth Bioengineering National Research Lab, School of Dentistry, Seoul National University, Seoul 110-749, Korea
| | - Joo-Cheol Park
- From the Department of Oral Histology-Developmental Biology, Dental Research Institute, Seoul 110-749, Korea.
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Zhao Z, Tang L, Deng Z, Wen L, Jin Y. Essential role of ADAM28 in regulating the proliferation and differentiation of human dental papilla mesenchymal cells (hDPMCs). Histochem Cell Biol 2008; 130:1015-25. [PMID: 18690470 DOI: 10.1007/s00418-008-0467-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2008] [Indexed: 12/23/2022]
Abstract
Dental papilla mesenchymal cells (DPMCs) have been supposed to possess the relatively independent and critical role for tooth development and morphogenesis. Here, we characterized the role of ADAM28, a member of a disintegrin and metalloproteinase (ADAM) family, in the regulative mechanisms of odontogenic capability of hDPMCs. Immunofluorescence staining showed the ubiquitous expression of ADAM28 in multiple human dental mesenchymal and epithelial cells. After confirming the effect of eukaryotic expression plasmid containing ADAM28 coding region and ADAM28 antisense oligodeoxynucleotide (AS-ODN), we respectively transfected them into hDPMCs and observed the biological markers for proliferation and differentiation. Overexpression of ADAM28 favored the proliferation and lineage-specific differentiation of hDPMCs, while blockage of ADAM28 exerted the opposite effects and induced apoptosis. These results identified an unrecognized hypothesis that ADAM28 may function as positive regulator of growth and differentiation of hDPMCs and act as an important molecule mediating reciprocal epithelial-mesenchymal signaling during tooth organ development.
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Affiliation(s)
- Zheng Zhao
- Research and Development Center for Tissue Engineering, Fourth Military Medical University, and Department of Otolaryngology, Xijing Hospital, 145 West Changle Road, 710032, Xi'an, China
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21
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Epithelial histogenesis during tooth development. Arch Oral Biol 2008; 54 Suppl 1:S25-33. [PMID: 18656852 DOI: 10.1016/j.archoralbio.2008.05.019] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 05/07/2008] [Accepted: 05/07/2008] [Indexed: 12/31/2022]
Abstract
This paper reviews the current understanding of the progressive changes mediating dental epithelial histogenesis as a basis for future collaborative studies. Tooth development involves morphogenesis, epithelial histogenesis and cell differentiation. The consecutive morphological stages of lamina, bud, cap and bell are also characterized by changes in epithelial histogenesis. Differential cell proliferation rates, apoptosis, and alterations in adhesion and shape lead to the positioning of groups of cells with different functions. During tooth histo-morphogenesis changes occur in basement membrane composition, expression of signalling molecules and the localization of cell surface components. Cell positional identity may be related to cell history. Another important parameter is cell plasticity. Independently of signalling molecules, which play a major role in inducing or modulating specific steps, cell-cell and cell-matrix interactions regulate the plasticity/rigidity of particular domains of the enamel organ. This involves specifying in space the differential growth and influences the progressive tooth morphogenesis by shaping the epithelial-mesenchymal junction. Deposition of a mineralized matrix determines the final shape of the crown. All data reviewed in this paper were investigated in the mouse.
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22
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Initiation and patterning of the snake dentition are dependent on Sonic Hedgehog signaling. Dev Biol 2008; 319:132-45. [DOI: 10.1016/j.ydbio.2008.03.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 02/28/2008] [Accepted: 03/04/2008] [Indexed: 11/21/2022]
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Asymmetrical growth, differential cell proliferation, and dynamic cell rearrangement underlie epithelial morphogenesis in mouse molar development. Cell Tissue Res 2007; 330:461-73. [DOI: 10.1007/s00441-007-0502-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 08/29/2007] [Indexed: 10/22/2022]
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Xie M, Kobayashi I, Kiyoshima T, Yamaza H, Honda JY, Takahashi K, Enoki N, Akamine A, Sakai H. Functional implication of nucleolin in the mouse first molar development. J Biol Chem 2007; 282:23275-83. [PMID: 17562718 DOI: 10.1074/jbc.m610779200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We examined the functional implication of nucleolin in the mouse first molar development. Both the nucleolin mRNA and protein expressions were demonstrated in the odontogenic epithelial cells in the early stage and in the inner enamel epithelial layer in the late stage. The expression pattern of nucleolin corresponded to the proliferating cells in the tooth germ, thus showing that nucleolin could possibly be related to cell proliferation. No in situ signal of nucleolin was found in the primary enamel knot (PEK). Furthermore, nucleolin protein was demonstrated in the PEK by immunohistochemistry. The existence of nucleolin protein in the PEK may possibly be related to the apoptosis in the PEK cells. An inhibition assay using the hemagglutinating virus of Japan-liposome containing nucleolin antisense phosphorothioated oligonucleotide (AS S-ODN) in cultured mouse mandibles at embryonic day (E) 11.0 showed a marked growth inhibition of tooth germ. Moreover, no developmental arrest was found in the cultured tooth germ at E15.0 treated with nucleolin AS S-ODN. Real time PCR was performed to examine the mRNA expression of nucleolin-related genes, and a significant reduction in the midkine mRNA expression was thus observed in the mouse mandible after being treated with nucleolin AS S-ODN. This inhibition assay indicated that nucleolin could thus be involved in the early stage of tooth germ initiation and morphogenesis, possibly by regulating the midkine expression.
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Affiliation(s)
- Ming Xie
- Laboratory of Oral Pathology and Medicine, Department of Endodontology and Operative Dentistry, Kyushu University, Graduate School of Dental Science, Fukuoka 812-8582, Japan
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Buchtová M, Boughner JC, Fu K, Diewert VM, Richman JM. Embryonic development of Python sebae – II: Craniofacial microscopic anatomy, cell proliferation and apoptosis. ZOOLOGY 2007; 110:231-51. [PMID: 17499982 DOI: 10.1016/j.zool.2007.01.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 01/21/2007] [Accepted: 01/23/2007] [Indexed: 10/23/2022]
Abstract
This study explores the microscopic craniofacial morphogenesis of the oviparous African rock python (Python sebae) spanning the first two-thirds of the post-oviposition period. At the time of laying, the python embryo consists of largely undifferentiated mesenchyme and epithelium with the exception of the cranial base and trabeculae cranii, which are undergoing chondrogenesis. The facial prominences are well defined and are at a late stage, close to the time when lip fusion begins. Later (11-12d), specializations in the epithelia begin to differentiate (vomeronasal and olfactory epithelia, teeth). Dental development in snakes is different from that of mammals in several aspects including an extended dental lamina with the capacity to form 4 sets of generational teeth. In addition, the ophidian olfactory system is very different from the mammalian. There is a large vomeronasal organ, a nasal cavity proper and an extraconchal space. All of these areas are lined with a greatly expanded olfactory epithelium. Intramembranous bone differentiation is taking place at stage 3 with some bones already ossifying whereas most are only represented as mesenchymal condensations. In addition to routine histological staining, PCNA immunohistochemistry reveals relatively higher levels of proliferation in the extending dental laminae, in osseous mesenchymal condensations and in the olfactory epithelia. Areas undergoing apoptosis were noted in the enamel organs of the teeth and osseous mesenchymal condensations. We propose that localized apoptosis helps to divide a single condensation into multiple ossification centres and this is a mechanism whereby novel morphology can be selected in response to evolutionary pressures. Several additional differences in head morphology between snakes and other amniotes were noted including a palatal groove separating the inner and outer row of teeth in the upper jaw, a tracheal opening within the tongue and a pharyngeal adhesion that closes off the pharynx from the oral cavity between stages 1 and 4. Our studies on these and other differences in the python will provide valuable insights into in developmental, molecular and evolutionary mechanisms of patterning.
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Affiliation(s)
- Marcela Buchtová
- Department of Oral Health Sciences, Life Sciences Institute, University of British Columbia, Life Sciences Centre, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
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Cho SW, Lee HA, Cai J, Lee MJ, Kim JY, Ohshima H, Jung HS. The primary enamel knot determines the position of the first buccal cusp in developing mice molars. Differentiation 2007; 75:441-51. [PMID: 17309607 DOI: 10.1111/j.1432-0436.2006.00153.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The enamel knot (EK), which is located in the center of bud and cap stage tooth germs, is a transitory cluster of non-dividing epithelial cells. The EK acts as a signaling center that provides positional information for tooth morphogenesis and regulates the growth of tooth cusps by inducing secondary EKs. The morphological, cellular, and molecular events leading to the relationship between the primary and secondary EKs have not been described clearly. This study investigated the relationship between the primary and secondary EKs in the maxillary and mandibular first molars of mice. The location of the primary EK and secondary EKs was investigated by chasing Fgf4 expression patterns in tooth germ at some intervals of in vitro culture, and the relationship between the primary EK and secondary EK was examined by tracing the primary EK cells in the E13.5 tooth germs which were frontally half sliced to expose the primary EK. After 48 hr, the primary EK cells in the sliced tooth germs were located on the buccal secondary EKs, which correspond to the future paracone in maxilla and protoconid in mandible. The Bmp4 expression in buccal part of the dental mesenchyme might be related with the lower growth in buccal epithelium than in lingual epithelium, and the Msx2 expressing area in epithelium was overlapped with the enamel cord (or septum) and cell dense area. The enamel cord might connect the primary EK with enamel navel to fix the location of the primary EK in the buccal side during the cap to bell stages. Overall, these results suggest that primary EK cells strictly contribute to form the paracone or protoconid, which are the main cusps of the tooth in the maxilla or mandible.
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Affiliation(s)
- Sung-Won Cho
- Division of Anatomy and Developmental Biology, Department of Oral Biology, Research Center for Orofacial Hard Tissue Regeneration, Yonsei Center of Biotechnology, Yonsei University, 134 Shinchon-Dong, Seodaemoon-Gu, Seoul 120-752, Korea
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27
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Guven G, Gunhan O, Akbulut E, Cehreli ZC. Investigation of proliferative activity in the developing human tooth using Ki-67 immunostaining. Med Princ Pract 2007; 16:454-9. [PMID: 17917446 DOI: 10.1159/000107751] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 02/18/2007] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE The aim of this study was to investigate the proliferation of the developing human tooth germ and its surrounding tissues using Ki-67 immunostaining. MATERIALS AND METHODS Sections of mandibular dental arch tissues collected from 4 cadaveric human fetuses of 13, 16, 21 and 30 weeks of gestation were used. The immunoreactivity of Ki-67 in the tissue sections was assessed visually under a light microscope. Immunohistochemical controls were performed by replacing the primary antibody with phosphate-buffered saline or normal rabbit lgG. RESULTS The control sections did not display Ki-67 immunoactivity. Specimens of 13 weeks of gestation revealed intense Ki-67 immunostaining throughout the entire developing mandibular primary molars. At 16 weeks of gestation, immunostaining was observed in the inner enamel epithelium and dental papilla, in conjunction with the dental lamina showing decreased immunostaining. At 21 weeks, Ki-67 immunostaining was observed only in the inner enamel epithelium and dental papilla. The immunoreactivity of active ameloblasts and odontoblasts decreased, along with the proliferation capacity of the dental lamina. At 30 weeks, both enamel and dentin formation was observed along the cusped aspect of the tooth germ. Ameloblasts and odontoblasts were no longer immunoreactive in this region, while both types of cells were immunoreactive at the cervical regions of the crown. Dental lamina cells showed disintegration and were totally Ki-67-negative at 30 weeks of gestation. CONCLUSION The Ki-67 immunoreactivity of the dental lamina decreased during intrauterine tooth development. Positive immunostaining was observed at specific sites in the enamel organ and dental papilla during the cap and bell stages.
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Affiliation(s)
- Gunseli Guven
- Department of Pediatric Dentistry, Center of Dental Sciences, Faculty of Dentistry, Hacettepe University, Ankara, Turkey.
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Nakasone N, Yoshie H, Ohshima H. The relationship between the termination of cell proliferation and expression of heat-shock protein-25 in the rat developing tooth germ. Eur J Oral Sci 2006; 114:302-9. [PMID: 16911101 DOI: 10.1111/j.1600-0722.2006.00362.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Odontoblast- and ameloblast-lineage cells acquire heat-shock protein (HSP)-25 immunoreactivity after they complete cell division during postnatal odontogenesis in rat molars. However, there are no data available concerning the relationship between the termination of cell proliferation and HSP-25 immunoreactivity during tooth morphogenesis. We compared the expression of HSP-25 in tooth germs with their proliferative activity in the rat prenatal to perinatal molar and postnatal incisor to clarify the functional significance of HSP-25 during tooth morphogenesis by immunohistochemistry using anti-HSP-25 and anti-Ki67/5-bromo-2'-deoxyuridine (BrdU). Numerous proliferating cells in developing molars were distributed throughout the tooth germ and HSP-25 immunoreactivity was recognizable in the dental epithelial and mesenchymal cells after they completed cell division. However, both cell proliferation and immunoreaction for HSP-25 are absent in the enamel knots. The distribution pattern of the proliferating cells in the incisors was basically identical to that in the prenatal molars except for the lack of non-proliferating secondary enamel knots and the sparse distribution of proliferating cells in the apical bud. Thus, HSP-25 protein is suggested to act as a switch between cell proliferation and terminal cyto-differentiation during odontogenesis.
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Affiliation(s)
- Naohiro Nakasone
- Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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Iwatsuki S, Honda MJ, Harada H, Ueda M. Cell proliferation in teeth reconstructed from dispersed cells of embryonic tooth germs in a three-dimensional scaffold. Eur J Oral Sci 2006; 114:310-7. [PMID: 16911102 DOI: 10.1111/j.1600-0722.2006.00385.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Tissue engineering can now reproduce tooth from postnatal tooth cells. However, crown formation is not accurately reconstituted, even when the complex structure of the enamel dentin is reproduced. Here, we showed that a tissue-engineered (TE) tooth, exhibiting morphogenesis according to regular crown-cusp pattern formation, was produced by embryonic tooth germ cells in a three-dimensional scaffold. Heterogeneous cells dissociated from embryonic day 14 (E14) mice tooth germs were seeded on a scaffold and implanted under a kidney capsule in adult mice. The developmental process of the implants was examined for up to 14 d. At 5 d, the cells had formed initial tooth germ, followed by enamel-covered dentin tissue formed symmetrically. To study the developmental process, we examined the growth pattern using 5-bromo-2'-deoxyuridine (BrdU)-labeling analysis. The initial cell-proliferation patterns of the TE teeth were similar to that at the cap and early bell stages in natural teeth. This was particularly true in the cervical loop, which showed a similar distribution pattern of BrdU-positive cells in TE- and natural teeth. These results suggested that even when embryonic tooth germs are dissociated, the single cells can reconstitute tooth, and that enamel organ morphogenesis proceeds as in natural teeth.
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Affiliation(s)
- Shinji Iwatsuki
- Tooth Regeneration, Division of Stem Cell Engineering, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
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Willberg J, Syrjänen S, Hormia M. Junctional epithelium in rats is characterized by slow cell proliferation. J Periodontol 2006; 77:840-6. [PMID: 16671877 DOI: 10.1902/jop.2006.050213] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND The integrity of junctional epithelium (JE) and a firm epithelial adhesion to the tooth surface are maintained by the balance between cell proliferation and cell death. Maintaining the JE structure is essential for the protection of periodontal connective tissues against oral microbes. In this study, the proliferative activity and the expression of caspase 3, a cysteine protease associated with cell death, were studied in rat JE and other epithelial structures during molar tooth development. METHODS Fourteen rats aged 10 to 70 days were injected with bromodeoxyuridine (BrdU). Samples of first and second molars were selected for immunohistochemical staining. BrdU incorporation was studied in oral epithelium (OE) covering the erupting tooth, reduced enamel epithelium (REE), and gingival epithelium (GE), sulcular epithelium (SE), and JE. Samples were also subjected to immunohistochemical analysis for proliferating cell nuclear antigen (PCNA) and caspase 3. RESULTS The basal cells of the GE were actively proliferating, but in the JE, only a few cells were positive for BrdU or PCNA immunostaining. Some outer REE cells were proliferating during tooth eruption. Caspase 3 expression was in specific areas of REE after completion of amelogenesis. CONCLUSIONS Results showed slow proliferative activity in the rat JE. However, specific studies on cellular turnover and cell migration are needed to understand tissue homeostasis in this area.
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Affiliation(s)
- Jaana Willberg
- Department of Periodontology, Institute of Dentistry, University of Turku, Turku, Finland.
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31
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Nakasone N, Yoshie H, Ohshima H. An immunohistochemical study of the expression of heat-shock protein-25 and cell proliferation in the dental pulp and enamel organ during odontogenesis in rat molars. Arch Oral Biol 2006; 51:378-86. [PMID: 16259940 DOI: 10.1016/j.archoralbio.2005.09.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2005] [Revised: 08/14/2005] [Accepted: 09/19/2005] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The aim of this study is to clarify the functional significance of heat-shock protein (HSP)-25 during tooth development. DESIGN We compared the expression of HSP-25 in the dental epithelial and mesenchymal cells with their proliferative activity during odontogenesis in rat molars on postnatal days 1-100 by immunohistochemistry using anti-HSP-25 and anti-5-bromo-2'-deoxyuridine (BrdU) for cell proliferation assay. RESULTS On day 1, BrdU-immunoreactive cells were densely located in the inner enamel epithelium in the cervical loop and intercusped areas and the dental pulp adjacent to them, whereas HSP-25-immunoractivity (IR) was restricted to the cusped area where odontoblasts and ameloblasts had already differentiated. Subsequently, BrdU-IR shifted in the apical direction to be localized around Hertwig's epithelial root sheath during days 5-30, never overlapping with concomitantly apically-shifted HSP-25-IR. On days 60-100, BrdU-immunoreactive cells were hardly recognizable in the dental pulp, where HSP-25-IR was exclusively localized in the odontoblast layer. Furthermore, the odontoblast- and ameloblast-lineage cells exhibited two steps in the expression of HSP-25 throughout the postnatal stages: first, dental epithelial and pulpal mesenchymal cells showed a weak IR for HSP-25 after the cessation of their proliferative activity, and subsequently odontoblasts and ameloblasts consistently expressed an intense HSP-25-IR. CONCLUSION Odontoblast- and ameloblast-lineage cells acquire HSP-25-IR after they complete their cell division, suggesting that this protein acts as a switch between cell proliferation and differentiation during tooth development. The consistent expression of HSP-25-IR in the formative cells may be involved in the maintenance of their functional integrity.
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Affiliation(s)
- Naohiro Nakasone
- Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Niigata 951-8514, Japan
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32
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Akhter M, Kobayashi I, Kiyoshima T, Matsuo K, Yamaza H, Wada H, Honda JY, Ming X, Sakai H. Possible functional involvement of thymosin beta 4 in developing tooth germ of mouse lower first molar. Histochem Cell Biol 2005; 124:207-13. [PMID: 16133119 DOI: 10.1007/s00418-005-0040-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2005] [Indexed: 12/01/2022]
Abstract
We examined the detailed in situ expression pattern of thymosin beta 4 (Tbeta4) in the developing mouse mandibular first molar. Tbeta4 mRNA was expressed in the presumptive dental epithelium at embryonic day 10.5 (E10.5) and in the thickened dental epithelium at E12. An in situ signal was observed in the invaginated epithelial bud at E13, in the enamel organ at E14 and E14.5, and in the primary enamel knot (PEK) at E14.5. The signal was localized in the epithelial cells of the outer layer of the enamel organ at E15 and E15.5. No signal was found in the PEK at these stages. Tbeta4 mRNA was expressed in the inner enamel epithelium, cervical loop and dental lamina at E16 and E17. The expression of Tbeta4 mRNA was observed in the polarized inner epithelial cells at E18, newborn day 1 (N1) and N2. However, the signal intensity decreased markedly at N3. We herein report for the first time that Tbeta4 is distinctly expressed in developing tooth germ, and it may also play functional roles in the initiation, growth and differentiation of tooth germ.
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Affiliation(s)
- Merina Akhter
- Laboratory of Oral Pathology and Medicine, Kyushu University Graduate School of Dental Science, 3-1-1 Maidashi, Fukuoka, 812-8582, Japan
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33
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Matalova E, Witter K, Misek I. Apoptosis distribution in the first molar tooth germ of the field vole (Microtus agrestis). Tissue Cell 2004; 36:361-7. [PMID: 15385152 DOI: 10.1016/j.tice.2004.06.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2004] [Revised: 06/11/2004] [Accepted: 06/17/2004] [Indexed: 11/16/2022]
Abstract
Apoptosis represents an important process in organ and tissue morphogenesis and remodeling during embryonic development. A role for apoptosis in shape formation of developing teeth has been suggested. The field vole is a useful model for comparative studies in odontogenesis, particularly because of its contrasting molar morphogenesis when compared to the mouse. However, little is known concerning apoptosis in tooth development of this species. Morphological (cellular and nuclear alterations) and biochemical (specific DNA breaks--TUNEL staining) characteristics of apoptotic cells were used to evaluate the temporal and spatial occurrence of apoptosis in epithelial and mesenchymal tissues of the developing first molar tooth germs of the field vole. Apoptotic cells were found in non-proliferating areas (identified previously) throughout bud to bell stages, particularly in the epithelium, however, scattered also in the mesenchyme. A high concentration of TUNEL positive cells was evident in primary enamel knots at late bud stage with increasing density of apoptotic cells until ED 16 when the primary enamel knot in the field vole disappears and mesenchyme becomes protruded in the middle axes of the bell forming two shallow areas with zig-zag located secondary enamel knots. Distribution of TUNEL positive cells corresponded with localisation of secondary enamel knots as shown using histological and 3D analysis. Apoptosis was shown to be involved in the first molar development of the field vole, however, exact mechanisms and roles of this process in tooth morphogenesis require further investigation.
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Affiliation(s)
- E Matalova
- Laboratory of Genetics and Embryology IAPG CAS, Institute of Animal Physiology and Genetics, Academy of Sciences, Veveri 97, 602 00 Brno, Czech Republic.
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Abstract
Programmed cell death (apoptosis) constitutes an important mechanism in embryonic development. Although there is substantial evidence for essential roles of apoptosis in organ shaping and controlling of cell number, the mechanisms of these processes are poorly understood. The regulation of cell proliferation to form tooth buds of the appropriate size and at the correct positions must involve a balance between cell division and cell death. Apoptosis has been suggested to play both passive and active roles in bud formation and morphogenesis and in reduction of the dental lamina, as well as silencing of the enamel knot signaling centers. The location of apoptotic cells during tooth development has been described and suggests their temporospatial roles. Unfortunately, there is little functional evidence on these roles, and the aim of this review is to highlight areas where apoptosis may play key roles in odontogenesis.
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Affiliation(s)
- E Matalova
- Academy of Sciences, Institute of Animal Physiology and Genetics, Veveri 97, 602 00 Brno, Czech Republic
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Peterková R, Peterka M, Viriot L, Lesot H. Development of the vestigial tooth primordia as part of mouse odontogenesis. Connect Tissue Res 2003; 43:120-8. [PMID: 12489147 DOI: 10.1080/03008200290000745] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The mouse functional dentition comprises one incisor separated from three molars by a toothless diastema in each dental quadrant. Between the incisor and molars, the embryonic tooth pattern also includes vestigial dental primordia, which undergo regression involving apoptosis in their epithelium. Apoptosis appears to play an important role in achieving the specific tooth pattern in the mouse. We documented similarities in the folding mechanism allowing the formation of the dental lamina in mice as well as in reptiles. While further budding on this dental lamina gives rise to many individual simple tooth primordia in crocodiles and lizards, budding morphogenesis of several simple tooth primordia appears to be integrated in the mouse, giving rise to enamel organs of a complex nature. The differentiation of a mammalian tooth germ during both ontogeny and phylogeny might thus include the concrescence (connation) of more primordia, putatively corresponding to simple teeth in mammalian ancestors.
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Affiliation(s)
- R Peterková
- Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic.
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Matulová P, Witter K, Mísek I. Proliferating cell nuclear antigen (PCNA) expression in tooth primordia in the field vole (Microtus agrestis, Rodentia). Connect Tissue Res 2003; 43:138-42. [PMID: 12489149 DOI: 10.1080/03008200290001122] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cell proliferation in developing tooth germs has been studied particularly using bromodeoxyuridine (BrdU) incorporation into growing tooth primordia and by counting and three-dimensional (3D) reconstruction of mitoses in serial sections of developing teeth. PCNA has been proposed as an alternative marker of proliferation activity. The aim of our study was to detect immunohistochemically locations of PCNA-positive cells in developing tooth germs of Microtus agrestis (Rodentia). PCNA expression could be distinguished in oral epithelium and mesenchyme before first signs of dental lamina elevation. During bud, cap, and bell stages, positive immunostaining could be observed at defined sites in enamel organ, tooth papilla, and dental follicle. Rudimental tooth germs of the upper diastema, enamel knots, and inner enamel epithelium at day of ontogeny 18 and 19 showed negative reaction. PCNA marks cycling and early G0 cells and can be used successfully as a proliferation marker even in collection material.
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Affiliation(s)
- P Matulová
- Laboratory of Genetics and Embryology, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Veverí 97, 602 00 Brno 2, Czech Republic.
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Luukko K, Løes S, Furmanek T, Fjeld K, Kvinnsland IH, Kettunen P. Identification of a novel putative signaling center, the tertiary enamel knot in the postnatal mouse molar tooth. Mech Dev 2003; 120:270-6. [PMID: 12591596 DOI: 10.1016/s0925-4773(02)00458-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The final shape of the molar tooth crown is thought to be regulated by the transient epithelial signaling centers in the cusp tips, the secondary enamel knots (SEKs), which are believed to disappear after initiation of the cusp growth. We investigated the developmental fate of the signaling center using the recently characterized Slit1 enamel knot marker as a lineage tracer during morphogenesis of the first molar and crown calcification in the mouse. In situ hybridization analysis showed that after Fgf4 downregulation in the SEK, Slit1 expression persisted in the deep compartment of the knot. After the histological disappearance of the SEK, Slit1 expression was evident in a novel epithelial cell cluster, which we call the tertiary enamel knot (TEK) next to the enamel-free area (EFA)-epithelium at the cusp tips. In embryonic tooth, Slit1 was also observed in the stratum intermedium (SI) and stellate reticulum cells between the parallel SEKs correlating to the area where the inner enamel epithelium cells do not proliferate. After birth, the expression of Slit1 persisted in the SI cells of the transverse connecting lophs of the parallel cusps above the EFA-cells. These results demonstrate the presence of a novel putative signaling center, the TEK, in the calcifying tooth. Moreover, our results suggest that Slit1 signaling may be involved in the regulation of molar tooth shape by regulating epithelial cell proliferation and formation of EFA of the crown.
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Affiliation(s)
- Keijo Luukko
- Department of Anatomy and Cell Biology, University of Bergen, Arstadveien 19, N-5009, Bergen, Norway.
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Amasaki H, Ogawa M, Nagasao J, Mutoh KI, Ichihara N, Asari M. Distribution of apoptotic cells and apoptosis-related molecules in the developing murine palatine rugae. J Vet Med Sci 2002; 64:1103-6. [PMID: 12520101 DOI: 10.1292/jvms.64.1103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Distribution of apoptotic cells and expression of the apoptosis-related factors p53, bcl-2 and bad during morphogenesis of the murine palatine rugae (PR) were examined histochemically using the terminal deoxynucleotidyl transferase-mediated UTP nick end-labeling (TUNEL) technique and specific antibodies against apoptosis and cell cycle-related molecules. Formation of the PR rudiment was controlled by cell proliferation and apoptosis in the palatal epithelium. TUNEL-positive cells were detected only at the epithelial placode area at 12.5-13.5 days post coitus (dpc), but only a few cells were positive at the protruding PR area at 14.5-16.5 dpc. Bcl-2 protein was expressed mainly in the areas outside of those containing TUNEL-positive cells at 15.5 -6.5 dpc. P53 protein was not detected throughout gestation. Bad was detected in the epithelial layer at 13.5 and 15.5 dpc and overlapping the apoptotic area at 13.5-15.5 dpc. Apoptosis of palatal epithelial cells might therefore involve spatiotemporally regulated expression of bad during murine PR development.
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Affiliation(s)
- Hajime Amasaki
- Department of Veterinary Anatomy, Nippon Veterinary and Animal Science University, Musashino-shi, Tokyo, Japan
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Kohama K, Nonaka K, Hosokawa R, Shum L, Ohishi M. TGF-beta-3 promotes scarless repair of cleft lip in mouse fetuses. J Dent Res 2002; 81:688-94. [PMID: 12351667 DOI: 10.1177/154405910208101007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
TGF-beta3 mediates epithelial-mesenchymal transformation during normal fusion of lip and palate, but how TGF-beta3 functions during cleft lip repair remains unexplored. We hypothesize that TGF-beta3 promotes fetal cleft lip repair and fusion by increasing the availability of mesenchymal cells. In this investigation, we demonstrated that cleft lips in mouse fetuses were repaired by fetal surgery, producing scarless fusion. At the site of the operation, we first observed an infusion of platelets expressing TGF-beta3, followed by increased expression of cyclin D1 and tenascin-C, and coupled with increased mesenchymal cell proliferation. In an ex vivo serumless culture system, cleft lip explants fused in the presence of exogenous TGF-beta3. Cultured lips also showed up-regulation in cyclin D1 and tenascin-C expression. These findings suggest that microsurgical repair of cleft lip in the fetus that produced scarless fusion is mediated by TGF-beta3 regulation of mesenchymal cell proliferation and migration at the site of repair.
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Affiliation(s)
- K Kohama
- Graduate School of Dental Science, Faculty of Dental Science, Kyushu University, Maidashi, Fukuoka, Japan
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Wada H, Kobayashi I, Yamaza H, Matsuo K, Kiyoshima T, Akhtar M, Sakai T, Koyano K, Sakai H. In situ expression of heat shock proteins, Hsc73, Hsj2 and Hsp86 in the developing tooth germ of mouse lower first molar. THE HISTOCHEMICAL JOURNAL 2002; 34:105-9. [PMID: 12495215 DOI: 10.1023/a:1020930228303] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This study examined the detailed gene expression pattern of three different heat shock proteins (HSPs), Hsc73, Hsj2, and Hsp86, by means of an in situ hybridization method. Hsc73, Hsj2, and Hsp86 were shown in our previous study to be differentially expressed in the mouse embryonic mandible at day 10.5 (E10.5) gestational age. These HSP genes showed similar expression patterns during development of the mouse lower first molar. HSPs-expressing cells were widely distributed in both the epithelial and underlying ectomesenchymal cells at E10.5, and then were slightly localized at E12 in an area where the tooth germ of the lower first molar is estimated to be formed. A strong expression of HSPs was observed in the tooth germ at E13.5. At the cap stage, HSPs were expressed in the enamel organ and dental papilla. At the bell stage, HSPs were distinctly expressed in the inner enamel epithelium and dental papilla cells facing the inner enamel epithelial layer, which later differentiate into ameloblasts and odontoblasts, respectively. This study is the first report in which Hsc73, Hsj2, and Hsp86 were distinctly expressed in the developing tooth germ, thus suggesting these HSPs are related to the development and differentiation of odontogenic cells.
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Affiliation(s)
- Hiroko Wada
- Laboratory of Oral Pathology and Medicine, Faculty of Dental Science, Kyushu University 61, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Takanosu M, Amasaki H, Iwama Y, Ogawa M, Hibi S, Suzuki K. Epithelial cell proliferation and apoptosis in the developing murine palatal rugae. Anat Histol Embryol 2002; 31:9-14. [PMID: 11841352 DOI: 10.1046/j.1439-0264.2002.00351.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Epithelial cell proliferation and apoptosis during morphogenesis of the murine palatal rugae (PR) were examined histochemically by using anti-bromodeoxyuridine (BrdU) and the terminal deoxynucleotidyl transferase-mediated UTP nick-end-labelling (TUNEL) technique. Formation of the PR rudiment was observed as an epithelial placode in fetuses at 12.5 days post-coitus (dpc). During the PR formation, BrdU-positive cells were detected mainly in the epithelium of the interplacode and interprotruding areas in fetuses administered BrdU maternally at 2 h before killing. TUNEL-positive cells were detected only at the epithelial placode area in 12.5-14.5 dpc. At 16.5-18.5 dpc, the BrdU-positive cells were decreased in number in the epithelial cells at the interprotruding area of the PR. Only a few TUNEL-positive cells were observed in the protruding area of the PR at 16.5 dpc. These results suggest that cell proliferation and apoptosis in the palatal epithelium are involved spatiotemporally in the murine PR morphogenesis.
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Affiliation(s)
- M Takanosu
- Department of Veterinary Physiology, Nippon Veterinary and Animal Science University, Tokyo 180-8602, Japan
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Yamaza H, Matsuo K, Kobayashi I, Wada H, Kiyoshima T, Akhtar M, Ishibashi Y, Sakai T, Akamine A, Sakai H. Expression of Set-alpha during morphogenesis of mouse lower first molar. THE HISTOCHEMICAL JOURNAL 2001; 33:437-41. [PMID: 11931383 DOI: 10.1023/a:1014491111628] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The detailed in situ expression pattern of the Set-alpha gene has been studied. Previously we showed that Set-alpha is a differentially expressed gene in the embryonic mouse mandible at day 10.5 (E10.5) gestational age. Cells expressing Set-alpha were widely distributed in both the epithelial and underlying ectomesenchymal cells at E10.5. At E12, they were slightly aggregated in an area where tooth germ of the lower first molar is estimated to be formed. At E13.5, Set-alpha was strongly expressed in the tooth germ. At the cap stage, Set-alpha was expressed in the enamel organ and dental papilla. At the bell stage, Set-alpha was distinctly expressed in the inner enamel epithelial and dental papilla cells facing the inner enamel epithelial layer, which were intended to differentiate into ameloblasts and odontoblasts, respectively. Interestingly, Set-alpha was also expressed in several embryonic craniofacial tissues derived from the ectoderm. This study is the first report that Set-alpha is distinctly expressed in the developing tooth germ, and suggests that Set-alpha plays an important role in both the initiation and the growth of the tooth germ, as well as in the differentiation of ameloblasts and odontoblasts.
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Affiliation(s)
- H Yamaza
- Laboratory of Oral Pathology and Medicine, Faculty of Dental Science, Kyushu University 61, Fukuoka, Japan
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Shigemura N, Kiyoshima T, Sakai T, Matsuo K, Momoi T, Yamaza H, Kobayashi I, Wada H, Akamine A, Sakai H. Localization of activated caspase-3-positive and apoptotic cells in the developing tooth germ of the mouse lower first molar. THE HISTOCHEMICAL JOURNAL 2001; 33:253-8. [PMID: 11563537 DOI: 10.1023/a:1017900305661] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This study examined the immunohistochemical detection of activated caspase-3, and its association with apoptosis, during tooth morphogenesis of the mouse lower first molar. The distribution of cells positive for caspase-3 closely corresponded with the localization of the terminal deoxynucleotidyl transferase-mediated deoxyuridine-5'-triphosphate-biotin nick end labelling (TUNEL)-positive apoptotic cells through the developmental course of tooth germs from embryo day 12 (E12) to E19, thus showing that the apoptosis occurring in the developing odontogenic tissue was induced by the activation of the caspase family. The specific distribution pattern of apoptotic cells in the developing odontogenic epithelial tissue from the initiation (E12) of tooth germ to the completion of tooth crown morphology (E19) also suggests that apoptotic events are related not only to a deletion of functionally suspended cells, but also participate in initiation and the completion of tooth morphogenesis. Electron microscopic examination revealed that apoptotic cells were present in the primary enamel knot, and these apoptotic cells were phagocytized by neighbouring odontogenic epithelial cells, thus indicating the prompt disposal of any dead cells by epithelial cells.
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Affiliation(s)
- N Shigemura
- Laboratory of Oral Pathology and Medicine, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
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