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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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Ricucci D, Loghin S, Niu LN, Tay FR. Changes in the radicular pulp-dentine complex in healthy intact teeth and in response to deep caries or restorations: A histological and histobacteriological study. J Dent 2018; 73:76-90. [DOI: 10.1016/j.jdent.2018.04.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 04/08/2018] [Accepted: 04/11/2018] [Indexed: 12/18/2022] Open
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Bronckers AL, Lyaruu DM. Magnesium, pH regulation and modulation by mouse ameloblasts exposed to fluoride. Bone 2017; 94:56-64. [PMID: 27744011 DOI: 10.1016/j.bone.2016.10.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 10/05/2016] [Accepted: 10/10/2016] [Indexed: 12/25/2022]
Abstract
Supraoptimal intake of fluoride (F) induces structural defects in forming enamel, dentin and bone and increases the risk of bone fractures. In comparison to bone and dentin is formation of enamel most sensitive to low levels of F and the degree of enamel fluorosis depends on the mouse strain. What molecular mechanism is responsible for these differences in sensitivity is unclear. Maturation ameloblasts transport bicarbonates into enamel in exchange for Cl- to buffer protons released by forming apatites. We proposed that F-enhanced mineral deposition releases excess of protons that will affect mineralization in forming enamel. In this study we tested the hypothesis that increased sensitivity to F is associated with a reduced capacity of ameloblasts to buffer acids. Quantified electron probe microanalysis showed that enamel of F-sensitive C57Bl mice contained the same levels of Cl- as enamel of F-resistant FVB mice. Enamel of C57Bl mice was less mineral dense, contained less Ca but more Mg and K. Ameloblast modulation was much more impaired than in FVB mice. In enamel of FVB mice the levels of Mg correlated negative with Ca (r=-0.57, p=0.01) and with the Ca/P molar ratio (r=-0.32, p=0.53). In moderate and high acidic enamel the correlations between Mg and Ca/P ratio were strong (r=-0.75, p=0.08) to very strong negative (r=-0.98, p=0.0020), respectively. Correlations in enamel between F and Ca were (weak) negative but between F and Ca/P very high positive (r=+0.95, p=0.003) in high acidic enamel and less positive (r=0.45, p=0.27) in moderate acidic fluorotic enamel (r=0.45, p=0.27). Similar correlations between Mg and Ca/P or F and Ca/P were found in dentin and bone of fluorotic and Cftr null mice. These data are consistent with the concept that Mg delays but F increases maturation of crystals particularly when enamel is acidic. The sensitivity of forming enamel to F likely is due to the sensitivity of pH cycling to acidification of enamel associated with F-induced release of protons.
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Affiliation(s)
- Antonius Ljj Bronckers
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, The Netherlands.
| | - Donacian M Lyaruu
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, The Netherlands
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Pei F, Lin H, Liu H, Li L, Zhang L, Chen Z. Dual role of autophagy in lipopolysaccharide-induced preodontoblastic cells. J Dent Res 2014; 94:175-82. [PMID: 25297117 DOI: 10.1177/0022034514553815] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Odontoblasts derive from neural crest-derived odontogenic mesenchymal cells, and they are an important barrier of defense for the host. Survival and immunity of odontoblasts play important roles in protecting the dentin-pulp structure. Autophagy can eliminate damaged organelles and recycle cellular components to facilitate cellular homeostasis. Autophagy can be activated with external stressors, such as starvation, hypoxia, and infection. In this study, the role of autophagy in inflamed odontoblasts was explored, and its possible mechanism was investigated. Cell viability was not affected by mild lipopolysaccharide (LPS) stimulation, and autophagy was activated during this process. Immunofluorescence of light chain 3 confirmed that autophagy was induced with LPS treatment. Early-stage autophagy inhibition resulted in down-regulated cell viability, contrary to the up-regulated cell viability at late-stage autophagy inhibition. Western blot suggested that p-Akt and survivin were not activated in the early stage, and they gradually increased and peaked in the late stage. Meanwhile, autophagy was down-regulated through the Akt/mTOR/survivin pathway in the late stage. Thus, autophagy has a dual role in inflamed odontoblasts, which indicates its importance in maintaining the microenvironment homeostasis of odontoblasts. Autophagy was induced as a survival mechanism in the early stage, and it decreased through the Akt/mTOR/survivin signaling pathway in the late stage.
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Affiliation(s)
- F Pei
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - H Lin
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - H Liu
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - L Li
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - L Zhang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Z Chen
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
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Bronckers ALJJ, Gueneli N, Lüllmann-Rauch R, Schneppenheim J, Moraru AP, Himmerkus N, Bervoets TJ, Fluhrer R, Everts V, Saftig P, Schröder B. The intramembrane protease SPPL2A is critical for tooth enamel formation. J Bone Miner Res 2013; 28:1622-30. [PMID: 23426979 DOI: 10.1002/jbmr.1895] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/06/2013] [Accepted: 02/11/2013] [Indexed: 12/15/2022]
Abstract
Intramembrane proteases are critically involved in signal transduction and membrane protein turnover. Signal-peptide-peptidase-like 2a (SPPL2A), a presenilin-homologue residing in lysosomes/late endosomes, cleaves type II-oriented transmembrane proteins. We recently identified SPPL2A as the enzyme controlling turnover and functions of the invariant chain (CD74) of the major histocompatibility complex II (MHCII) and demonstrated critical importance of this process for B cell development. Surprisingly, we found that SPPL2A is critical for formation of dental enamel. In Sppl2a knockout mice, enamel of the erupted incisors was chalky white and rapidly eroded after eruption. SPPL2A was found to be expressed in enamel epithelium during secretory and maturation stage amelogenesis. Mineral content of enamel in Sppl2a⁻/⁻ incisors was inhomogeneous and reduced by ∼20% compared to wild-type mice with the most pronounced reduction at the mesial side. Frequently, disruption of the enamel layer and localized detachment of the most superficial enamel layer was observed in the knockout incisors leading to an uneven enamel surface. In Sppl2a null mice, morphology and function of secretory stage ameloblasts were not noticeably different from that of wild-type mice. However, maturation stage ameloblasts showed reduced height and a characteristic undulation of the ameloblast layer with localized adherence of the cells to the outer enamel. This was reflected in a delayed and incomplete resorption of the proteinaceous enamel matrix. Thus, we conclude that intramembrane proteolysis by SPPL2A is essential for maintaining cellular homeostasis of ameloblasts. Because modulation of SPPL2A activity appears to be an attractive therapeutic target to deplete B cells and treat autoimmunity, interference with tooth enamel formation should be investigated as a possible adverse effect of pharmacological SPPL2A inhibitors in humans.
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Tjäderhane L, Haapasalo M. The dentin-pulp border: a dynamic interface between hard and soft tissues. ACTA ACUST UNITED AC 2012. [DOI: 10.1111/j.1601-1546.2012.00266.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Matalova E, Svandova E, Tucker AS. Apoptotic signaling in mouse odontogenesis. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2011; 16:60-70. [PMID: 22204278 DOI: 10.1089/omi.2011.0039] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Apoptosis is an important morphogenetic event in embryogenesis as well as during postnatal life. In the last 2 decades, apoptosis in tooth development (odontogenesis) has been investigated with gradually increasing focus on the mechanisms and signaling pathways involved. The molecular machinery responsible for apoptosis exhibits a high degree of conservation but also organ and tissue specific patterns. This review aims to discuss recent knowledge about apoptotic signaling networks during odontogenesis, concentrating on the mouse, which is often used as a model organism for human dentistry. Apoptosis accompanies the entire development of the tooth and corresponding remodeling of the surrounding bony tissue. It is most evident in its role in the elimination of signaling centers within developing teeth, removal of vestigal tooth germs, and in odontoblast and ameloblast organization during tooth mineralization. Dental apoptosis is caspase dependent and proceeds via mitochondrial mediated cell death with possible amplification by Fas-FasL signaling modulated by Bcl-2 family members.
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Affiliation(s)
- Eva Matalova
- Institute of Animal Physiology and Genetics, v.v.i., Academy of Sciences, Brno, Czech Republic.
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The novel function of Oct3/4 in mouse tooth development. Histochem Cell Biol 2011; 137:367-76. [DOI: 10.1007/s00418-011-0895-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2011] [Indexed: 10/14/2022]
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Zhang W, Ju J. Odontoblast-targeted Bcl-2 overexpression promotes dentine damage repair. Arch Oral Biol 2011; 57:285-92. [PMID: 21930259 DOI: 10.1016/j.archoralbio.2011.08.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 08/24/2011] [Accepted: 08/29/2011] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Bcl-2 is widely expressed in a developing tooth organ and regulates tooth morphogenesis. However, whether Bcl-2 is related to tooth damage repair is unknown yet. Using an odontoblast-targeted Bcl-2 overexpression transgenic mouse (Col2.3Bcl-2) and artificial cavity preparation as a model system, the relationship between Bcl-2 and reparative dentinogenesis is investigated in this study. METHODS The odontoblastic-like cell cultures derived from mouse molar pulps were established. The expression of transgenic human Bcl-2 (hBcl-2) and endogenous mouse Bcl-2 (mBcl-2) and mouse Bax (mBax, a Bcl-2 antagonist) was detected in vivo and in vitro by Western blot and immunocytochemistry, respectively. Basal level and artificial cavity-induced odontoblast apoptosis was detected by the Deoxynucleotidyl Transferase (TdT) dUTP Nick End labelling (TUNEL) technique. Reparative dentine formation induced by artificial cavity drilled to a half dentine thickness on mesial cervical region of mandibular first molars 2, 4, and 6 weeks post-op was evaluated histologically and via micro-CT. RESULTS The transgenic hBcl-2 was stably expressed in odontoblasts of the transgenic animals without interference with the expression of mBcl-2 and mBax. Basal level as well as artificial cavity- induced odontoblast apoptosis was prevented by the transgene. Compared to the wild type, the transgenic animals produced reparative dentine with significantly higher mineral density 6 weeks after the operation. CONCLUSIONS Bcl-2 overexpression prevents odontoblast apoptosis and promotes dentine damage repair, indicating that genetic manipulation of Bcl-2 may be a novel strategy to maintain the vitality and function of dentine-pulp complex under detrimental mechanical stimuli.
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Affiliation(s)
- Wenjian Zhang
- Department of Diagnostic Sciences, University of Texas School of Dentistry at Houston, 77030, USA.
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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: 50] [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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Mitsiadis TA, De Bari C, About I. Apoptosis in developmental and repair-related human tooth remodeling: a view from the inside. Exp Cell Res 2007; 314:869-77. [PMID: 18054913 DOI: 10.1016/j.yexcr.2007.11.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 11/02/2007] [Accepted: 11/03/2007] [Indexed: 10/22/2022]
Abstract
Apoptosis is a key phenomenon in the regulation of the life span of odontoblasts, which are responsible for dentin matrix production of the teeth. The mechanism controlling odontoblasts loss in developing, normal, and injured human teeth is largely unknown. A possible correlation between apoptosis and dental pulp volume reduction was examined. Histomorphometric analysis was performed on intact 10 to 14 year-old premolars to follow dentin deposition and evaluate the total number of odontoblasts. Apoptosis in growing healthy teeth as well as in mature irritated human teeth was determined using a modified TUNEL technique and an anti-caspase-3 antibody. In intact growing teeth, the sequential rearrangement of odontoblasts into a multi-layer structure during tooth crown formation was correlated with an apoptotic wave that leads to the massive elimination of odontoblasts. These data suggest that apoptosis, coincident with dentin deposition changes, plays a role in tooth maturation and homeostasis. Massive apoptotic events were observed after dentin irritation. In carious and injured teeth, apoptosis was detected in cells surrounding the lesion sites, as well as in mono-nucleated cells nearby the injury. These results indicate that apoptosis is a part of the mechanism that regulate human dental pulp chamber remodeling during tooth development and pathology.
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Affiliation(s)
- Thimios A Mitsiadis
- Institute of Oral Biology, Department of Orofacial Development and Structure, Faculty of Medicine, University of Zurich, Plattenstrasse 11, 8032 Zurich, Switzerland.
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Nomiyama K, Kitamura C, Tsujisawa T, Nagayoshi M, Morotomi T, Terashita M, Nishihara T. Effects of Lipopolysaccharide on Newly Established Rat Dental Pulp–derived Cell Line with Odontoblastic Properties. J Endod 2007; 33:1187-91. [PMID: 17889687 DOI: 10.1016/j.joen.2007.05.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 05/18/2007] [Accepted: 05/24/2007] [Indexed: 01/09/2023]
Abstract
To clarify mechanisms of pulp wound healing and regeneration, it is important to establish continuous odontoblast-lineage cell lines. In this study, we established the proliferating pulp progenitor cell lines from dental papilla cells of rat incisor. These cell lines showed high levels of alkaline phosphatase (ALP) activity, expression of Runx2 and dentin sialophosphoprotein (DSPP), and extracellular formation of mineralized nodules. By using the cell line with high expression level of DSPP and the prominent mineral deposition, we examined whether bacterial lipopolysaccharide (LPS) had effects on its odontoblastic properties and found that ALP activity, expression of DSPP and Runx2, and the formation of mineralized nodules were suppressed in LPS dose-dependent manner. These results indicate that our established pulp progenitor cell line exhibits odontoblastic properties, which were suppressed by LPS, suggesting that gram-negative bacterial infection might downregulate the odontoblast function.
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Affiliation(s)
- Kimiko Nomiyama
- Department of Health Promotion, Division of Infections and Molecular Biology, Kyushu Dental College, Fukuoka, 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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Kawagishi E, Nakakura-Ohshima K, Nomura S, Ohshima H. Pulpal responses to cavity preparation in aged rat molars. Cell Tissue Res 2006; 326:111-22. [PMID: 16767403 DOI: 10.1007/s00441-006-0230-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Accepted: 04/25/2006] [Indexed: 10/24/2022]
Abstract
The dentin-pulp complex is capable of repair after tooth injuries including dental procedures. However, few data are available concerning aged changes in pulpal reactions to such injuries. The present study aimed to clarify the capability of defense in aged pulp by investigating the responses of odontoblasts and cells positive for class II major histocompatibility complex (MHC) to cavity preparation in aged rat molars (300-360 days) and by comparing the results with those in young adult rats (100 days). In untreated control teeth, immunoreactivity for intense heat-shock protein (HSP)-25 and nestin was found in odontoblasts, whereas class-II-MHC-positive cells were densely distributed in the periphery of the pulp. Cavity preparation caused two types of pulpal reactions based on the different extent of damage in the aged rats. In the case of severe damage, destruction of the odontoblast layer was conspicuous at the affected site. By 12 h after cavity preparation, numerous class-II-MHC-positive cells appeared along the pulp-dentin border but subsequently disappeared together with HSP-25-immunopositive cells, and finally newly differentiated odontoblast-like cells took the place of the degenerated odontoblasts and acquired immunoreactivity for HSP-25 and nestin by postoperative day 3. In the case of mild damage, no remarkable changes occurred in odontoblasts after operation, and some survived through the experimental stages. These findings indicate that aged pulp tissue still possesses a defense capacity, and that a variety of reactions can occur depending on the difference in the status of dentinal tubules and/or odontoblast processes in individuals.
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Affiliation(s)
- Eriko Kawagishi
- Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, and Polyclinic Intensive Oral Care Unit, Niigata University Medical and Dental Hospital, Japan
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Srisuwan T, Tilkorn DJ, Wilson JL, Morrison WA, Messer HM, Thompson EW, Abberton KM. Molecular aspects of tissue engineering in the dental field. Periodontol 2000 2006; 41:88-108. [PMID: 16686928 DOI: 10.1111/j.1600-0757.2006.00176.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Tanida Srisuwan
- Bernard O'Brien Institute of Microsurgery, Fitzroy, Victoria, Australia
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He WX, Niu ZY, Zhao SL, Smith AJ. Smad protein mediated transforming growth factor β1 induction of apoptosis in the MDPC-23 odontoblast-like cell line. Arch Oral Biol 2005; 50:929-36. [PMID: 16183370 DOI: 10.1016/j.archoralbio.2005.03.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Accepted: 03/09/2005] [Indexed: 12/22/2022]
Abstract
OBJECTIVE The function of apoptosis and its regulation in odontoblasts remain unclear. In this study, we characterize the possible role of transforming growth factor (TGF)-beta 1 in the induction of apoptosis and the molecular mechanisms that mediate TGF-beta1-induced apoptosis in odontoblasts. METHODS Annexin V/propidium iodide staining, cell Death Detection ELISA and DNA ladder were used to examine the effect of TGF-beta1 on apoptosis in a mouse odontoblast-like cell line, MDPC-23. Stable cell clones expressing Smad2 or Smad3 dominant negative mutants, or wild-type Smad7 were constructed to investigate the role of Smad proteins in the mediation of apoptosis by TGF-beta1 in MDPC-23 cells. The TGF-beta1-induced transcriptional activity in stable cell clones expressing Smad proteins was analyzed by a transient transfected TGF-beta-responsive reporter gene, p3TP-Lux. RESULTS TGF-beta1 can induce apoptotic cell death in MDPC-23 cells in a dose-dependent manner. Transfection of dominant negative mutant forms of Smad2 or Smad3 blocked TGF-beta1-induced apoptosis; moreover, the Smad3 mutant was more efficient than the Smad2 mutant. Transfection of Smad7, an inhibitory Smad, also significantly inhibited TGF-beta1-induced apoptosis of these cells. Over-expression of Smad3 dominant negative mutant or Smad7 significantly inhibited TGF-beta1-induced transcriptional activity. CONCLUSION These results suggest that Smad proteins are involved in TGF-beta1-induced apoptosis of odontoblast cells.
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Affiliation(s)
- Wen-Xi He
- Department of Conservative Dentistry, Qin Du Stomatological Hospital, School of Dentistry, The Fourth Military Medical University, Xi'an 710032, PR China.
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Kubota K, Lee DH, Tsuchiya M, Young CS, Everett ET, Martinez-Mier EA, Snead ML, Nguyen L, Urano F, Bartlett JD. Fluoride induces endoplasmic reticulum stress in ameloblasts responsible for dental enamel formation. J Biol Chem 2005; 280:23194-202. [PMID: 15849362 DOI: 10.1074/jbc.m503288200] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism of how fluoride causes fluorosis remains unknown. Exposure to fluoride can inhibit protein synthesis, and this may also occur by agents that cause endoplasmic reticulum (ER) stress. When translated proteins fail to fold properly or become misfolded, ER stress response genes are induced that together comprise the unfolded protein response. Because ameloblasts are responsible for dental enamel formation, we used an ameloblast-derived cell line (LS8) to characterize specific responses to fluoride treatment. LS8 cells were growth-inhibited by as little as 1.9-3.8 ppm fluoride, whereas higher doses induced ER stress and caspase-mediated DNA fragmentation. Growth arrest and DNA damage-inducible proteins (GADD153/CHOP, GADD45alpha), binding protein (BiP/glucose-responsive protein 78 (GRP78), the non-secreted form of carbonic anhydrase VI (CA-VI), and active X-box-binding protein-1 (Xbp-1) were all induced significantly after exposure to 38 ppm fluoride. Unexpectedly, DNA fragmentation increased when GADD153 expression was inhibited by short interfering RNA treatment but remained unaffected by transient GADD153 overexpression. Analysis of control and GADD153(-/-) embryonic fibroblasts demonstrated that caspase-3 mediated the increased DNA fragmentation observed in the GADD153 null cells. We also demonstrate that mouse incisor ameloblasts are sensitive to the toxic effects of high dose fluoride in drinking water. Activated Ire1 initiates an ER stress response pathway, and mouse ameloblasts were shown to express activated Ire1. Ire1 levels appeared induced by fluoride treatment, indicating that ER stress may play a role in dental fluorosis. Low dose fluoride, such as that present in fluoridated drinking water, did not induce ER stress.
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Affiliation(s)
- Kaori Kubota
- Department of Cytokine Biology, Forsyth Institute, Harvard School of Dental Medicine, Boston, Massachusetts 02115, USA
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Leonardi R, Barbato E, Paganelli C, Lo Muzio L. Immunolocalization of heat shock protein 27 in developing jaw bones and tooth germs of human fetuses. Calcif Tissue Int 2004; 75:509-16. [PMID: 15654495 DOI: 10.1007/s00223-004-0077-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2004] [Accepted: 04/12/2004] [Indexed: 01/13/2023]
Abstract
27 kDa Heat shock protein (Hsp27), which is also identified as p29 estrogen-receptor associated protein, plays a crucial role in specific growth stages. It also seems to be involved in the balance between differentiation and apoptosis. To determine whether Hsp27 is involved during craniofacial development and odontogenesis, its expression was studied through immunohistochemistry of developing jaw bone as well as the odontogenesis of heads from human fetuses. Formalin-fixed paraffin-embedded specimens of 7 human fetuses (3 female, 4 male), obtained from miscarriages occurring between the 9th and 16th weeks of pregnancy, were examined by using a monoclonal antibody against Hsp27. Staining intensity (weak, +; moderate, ++; strong, +++) was evaluated semiquantitatively. The sample slice was cut through a coronal plane, which included eyes, nasal cavities, tongue, and primitive dental lamina with tooth germs. A transient and spatially restricted expression of Hsp27 in developing human jaw bones and teeth was observed. Osteoblasts around the uncalcified bone matrix showed Hsp27 immunoreaction products (+++), whereas osteocytes were not immunolabeled. In mandibular condyle, immunolabeling was restricted to hypertrophic chondrocytes (++). In developing tooth germs, Hsp27 immunostaining was detected throughout the bud (+++). At the early cap stage, a strong immunolabeling for Hsp27 was seen in the dental lamina (+++), and a moderate staining was seen in the outer dental epithelium (++). At the late cap stage, Hsp27 expression was detected in the outer dental epithelium (++) as well as in the cells of the future stellate reticulum (++). The spatiotemporal-restricted expression of Hsp27 in craniofacial bones during development suggests that this protein could be involved in the balance between differentiation and apoptosis, by modulating the viability of osteoblasts and chondrocytes. The specific regional and temporal expression patterns of Hsp27 during tooth development sustains that this small Hsp might be related to the morphogenesis and cytodifferentiation processes of tooth germs.
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Affiliation(s)
- R Leonardi
- Department of Medical and Surgical Sciences, II Dental Unit, University of Catania, Catania, Italy.
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19
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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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20
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Peterková R, Peterka M, Lesot H. The developing mouse dentition: a new tool for apoptosis study. Ann N Y Acad Sci 2004; 1010:453-66. [PMID: 15033770 DOI: 10.1196/annals.1299.083] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Developing limb or differentiating neural and blood cells are traditional models used to study programmed cell death in mammals. The developing mouse dentition can also be an attractive model for studying apoptosis regulation. Apoptosis is most extant during early odontogenesis in mice. The embryonic tooth pattern is comprised not only of anlagen of functional teeth (incisor, molars), but also of vestiges of ancestral tooth primordia that must be suppressed. Apoptosis is involved in (a) the elimination of vestigial tooth primordia in the prospective toothless gap (diastema) between the incisor and molars and (b) the shaping of germs in functional teeth. This type of apoptosis occurs in the dental epithelium according to a characteristic temporo-spatial pattern. Where apoptosis concentrates, specific signaling is also found. We proposed a hypothesis to explain the stimulation of apoptosis in the dental epithelium by integrating two concepts: (1) The regulation of epithelial budding by positional information generated from interactions between growth-activating and growth-inhibiting signals, and (2) apoptosis stimulation by the failure of death-suppressing signals. During the budding of the dental epithelium, local excess in growth inhibitors (e.g., Bmps) might lead to the epithelial cells' failure to receive adequate growth-activating (apoptosis-suppressing) signals (e.g., Fgfs). The resulting signal imbalance leads to cell "suicide" by apoptosis. Understanding of apoptosis regulation in the vestigial tooth primordia can help to elucidate the mechanism of their suppression during evolution and to identify factors essential for tooth survival. The latter knowledge will be important for developing a technology of tooth engineering.
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Affiliation(s)
- Renata Peterková
- Institute of Experimental Medicine, Academy of Sciences CR, Videnska 1083, 142 20 Prague 4, Czech Republic.
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21
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Huang Q, Singh B, Sharawy M. Immunohistochemical analysis of Bcl-2 and Bax oncoproteins in rabbit craniomandibular joint. Arch Oral Biol 2004; 49:143-8. [PMID: 14693208 DOI: 10.1016/j.archoralbio.2003.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The purpose of this study was to elucidate the expression of proto-oncogene Bcl-2 (anti-apoptotic) and Bax (pro-apoptotic) in fibrocartilage of the disc and hyaline cartilage of the condyle in the rabbit craniomandibular joint (CMJ). Ten New Zealand white rabbit heads were used. Sections were processed by the immunohistochemical techniques using mouse anti-Bcl-2 and anti-Bax antibodies. Intensity levels of immunostaining in condylar cartilage were quantified by a computer-image system. Immunoreactivity for Bcl-2 was mainly observed in the cytoplasm of the reserve cell and chondrocytic cell layers. A mild heterogeneous Bax expression was detected in the cytoplasm of chondrocytes of the upper hypertrophic layer and a few cells of the chondrocytic layer. The cytoplasm of chondrocytes in the disc exhibited a high intensity for Bcl-2, while Bax activity was only sporadically observed. We have shown that Bcl-2 and Bax proteins are present in CMJ cartilage and their expression patterns suggest that these oncoproteins are involved in chondrocyte survival or death via apoptotic pathways.
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Affiliation(s)
- Qin Huang
- Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, Augusta, GA 30912-1122, USA
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22
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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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23
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Abstract
Apoptosis plays an important role in many aspects of endodontics, yet there is a paucity of information in this regard in the endodontic literature. Apoptosis is a single deletion of scattered cells by fragmentation into membrane-bound particles that are phagocytosed by other cells. It is a key process in the embryological development of the tooth, periodontal ligament and supporting oral tissue in the progression of oral disease, bone resorption, immunological response and inflammation, and in wound healing and certain pharmacological effects. The understanding of the ability of clinical materials to induce or inhibit apoptosis and the investigation of apoptosis as it relates to the pathogenesis of pulpal and periradicular pathology may eventually lead to new treatment approaches for the endodontist. The purpose of this review is to familiarize the clinical endodontist with current knowledge on apoptosis as it relates to the pulp and periradicular tissues.
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Ohshima H, Nakakura-Ohshima K, Takeuchi K, Hoshino M, Takano Y, Maeda T. Pulpal regeneration after cavity preparation, with special reference to close spatio-relationships between odontoblasts and immunocompetent cells. Microsc Res Tech 2003; 60:483-90. [PMID: 12619124 DOI: 10.1002/jemt.10289] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The regeneration process of the odontoblast cell layer incident to tooth injury, especially its relationship with immunocompetent cells in pulp healing, has not been fully understood. The purpose of the present study was to clarify this relationship between odontoblasts and immunocompetent cells in the process of pulp regeneration following cavity preparation in rat molars by immunocytochemistry for heat shock protein (Hsp) 25 as well as class II major histocompatibility complex (MHC) molecules. In untreated control teeth, intense Hsp 25-immunoreactivity was found in the cell bodies of odontoblasts and their processes within the predentin, whereas class II MHC-positive cells were predominantly located beneath the odontoblast cell layer. Cavity preparation caused the destruction of the odontoblast layer to form an edematous lesion and the shift of class II MHC-positive cells with the injured odontoblasts toward the pulp core at the affected site. Some damaged odontoblasts without apparent cytoplasmic processes, round in profile, retained the immunoreactivity for Hsp25, suggesting the survival of a part of the odontoblasts against artificial external stimuli. Twelve hours after cavity preparation, numerous class II MHC-positive cells appeared along the pulp-dentin border and extended their processes deep into the exposed dentinal tubules. By postoperative 72 hours, newly differentiated odontoblasts with Hsp 25-immunoreactivity were arranged at the pulp-dentin border, but the class II MHC-positive cells moved from the pulp-dentin border to the subodontoblastic layer. These findings indicate that the time course of changes in the expression of Hsp 25-immunoreactivity reflects the regeneration process of odontoblasts. The functional roles of Hsp 25-positive odontoblasts and immunocompetent cells such as class II MHC-positive cells in the process of pulp regeneration after cavity preparation are discussed in conjunction with our previous experimental data.
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Affiliation(s)
- Hayato Ohshima
- 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, Japan.
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25
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Kitamura C, Ogawa Y, Nishihara T, Morotomi T, Terashita M. Transient co-localization of c-Jun N-terminal kinase and c-Jun with heat shock protein 70 in pulp cells during apoptosis. J Dent Res 2003; 82:91-5. [PMID: 12562879 DOI: 10.1177/154405910308200203] [Citation(s) in RCA: 28] [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
The c-Jun N-terminal kinase (JNK) pathway and heat-shock proteins (HSPs) are involved in stress-induced apoptosis. Here we examined the association of JNK, c-Jun, and anti-apoptotic HSPs with pulp apoptosis during wound healing. In normal pulp, c-Jun was activated only in a few pulp cells, but JNK was not. HSP70 was expressed in the cytoplasm of pulp cells. One day after injury, active JNK and c-Jun were detected in apoptotic pulp cells, whereas HSP70 was detected in non-apoptotic cells. We also found the translocation of HSP70 into nuclei of pulp cells, and co-localization with active JNK and c-Jun. Four days after injury, active JNK and c-Jun disappeared in pulp cells, and HSP70 was relocalized from nuclei to the cytoplasm. These results suggest that the JNK pathway may be one of the compartments inducing apoptosis in pulp cells, and that HSP70 may have an inhibitory role in the apoptosis of pulp cells during wound healing.
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Affiliation(s)
- C Kitamura
- Department of Operative Dentistry and Endodontics, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita, Kitakyushu 803-8580, Japan.
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26
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Kitamura C, Ogawa Y, Morotomi T, Terashita M. Differential induction of apoptosis by capping agents during pulp wound healing. J Endod 2003; 29:41-3. [PMID: 12540218 DOI: 10.1097/00004770-200301000-00011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Effects of capping agents on two waves of apoptosis during pulp wound healing were examined. After cavity preparation of rat molars, cavities were filled with calcium hydroxide, zing oxide eugenol cement, or 4-META/MMA-TBB resin (4MMT) and some were unfilled. One hour or 1 day after filling, we examined the distribution and the number of apoptotic cells by terminal deoxynucleotidyl transferase-mediated labeling (TUNEL) assay. One hour after filling, there were no differences in distribution patterns or the number of apoptotic odontoblasts among the four groups. One day after filling, we found differences in distribution patterns and the number of apoptotic pulp cells among the four groups. Especially in the 4MMT group, the distribution pattern of apoptotic cells was more broadly spread, and the number of apoptotic cells was significantly larger than those of other groups. These results suggest that capping agents may have an effect on pulp apoptosis and that 4MMT may actively induce apoptosis during pulp wound healing.
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Affiliation(s)
- Chiaki Kitamura
- Department of Operative Dentistry, Kyushu Dental College, Kokurakita, Kitakyushu, Japan
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27
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Abe T, Miyajima H, Okada K. Effects of a Macrolide Antibiotic on Enamel Formation in Rat Incisors-Primary Lesion of Ameloblast at the Transition Stage. J Vet Med Sci 2003; 65:985-8. [PMID: 14532690 DOI: 10.1292/jvms.65.985] [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: 11/22/2022] Open
Abstract
A novel macrolide antibiotic was administered orally to 5-week-old Jcl:Wistar rats at a dose of 5,000 mg/kg/day for 5 weeks, and then a half of animals were maintained without any treatment for 10 weeks. A white discolored lesion with horizontal stripes developed on the surface of the upper and lower incisors after dosing for 4 weeks, and these macroscopical incisal lesions disappeared with the eruption in 4 weeks after stop of administration. Histopathologically, increase in number of karyopycnosis of ameloblast at the transitional stage, vacuolar degeneration of ameloblast and cystic change in the maturation stage, and impaired iron pigment secretion at the pigmentation stage were observed. Microradiography, calcio-traumatic zones, which means hypocalcification, were observed on the superficial layer of enamel. These results suggest that the primary lesion induced by a novel macrolide antibiotic is the increased karyopycnosis of ameloblast at the transitional stage, and followed by later stage.
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28
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Tanabe K, Yoshiba K, Yoshiba N, Iwaku M, Ozawa H. Immunohistochemical study on pulpal response in rat molars after cavity preparation by Er:YAG laser. Eur J Oral Sci 2002; 110:237-45. [PMID: 12120710 DOI: 10.1034/j.1600-0722.2002.21282.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
While Er:YAG laser systems are in extensive use for caries removal and cavity preparation, the effects of such treatment on pulp tissue remain unclear. This study evaluates these systems using immunohistochemical methods and compares the results with information gained from treatment using conventional burs. Cervical cavities were prepared in the upper first molars of rats, using either an Er:YAG laser or a conventional tungsten-carbide bur. At intervals of 5 min, 6 h, 12 h, 1 d, 3 d and 7 d after cavity preparation, the teeth were processed for immunohistochemical analyses of tissue non-specific alkaline phosphatase, OX6-positive major histocompatibility complex class II antigen-expressing cells and PGP 9.5-immunoreactive nerve fibers. DNA fragmentation was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method. Tissue non-specific alkaline phosphatase was observed mainly in the subodontoblastic layer under the cavity lesion, from 5 min, in both groups. The immunoreactivity was more pronounced in the laser group, but by 7 d no significant differences were recognizable. At 12 h, TUNEL-positive cells were detected around the odontoblastic layer in both groups. From 3 d to 7 d, a limited number of positive cells were still visible in the group that underwent standard treatment. Clear similarities in the distribution patterns of OX6-immunopositive cells and PGP 9.5-immunoreactive nerve fibers were also noted. From 12 h to 1 d, OX6-positive cells accumulated along the pulp-dentin border, extending their processes into the dentinal tubules. Numerous bead-like PGP 9.5-immunoreactive nerve fibers were observed under the odontoblastic layer at 7 d. These results demonstrated that there was no appreciable difference in the manner in which pulp tissue responded to treatment with either Er:YAG laser or a conventional drill. This would seem to indicate the usefulness of the Er:YAG laser system in the removal of caries and cavity preparation.
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Affiliation(s)
- Keita Tanabe
- Department of Oral Health Science, Niigata University Graduate School of Medical and Dental Sciences, Japan
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29
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Itota T, Nishitani Y, Sogawa N, Sogawa C, Konishi N, Torii Y. Alteration of odontoblast osteonectin expression following dental cavity preparation. Arch Oral Biol 2001; 46:829-34. [PMID: 11420055 DOI: 10.1016/s0003-9969(01)00041-3] [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: 11/17/2022]
Abstract
Cavity preparation can increase the active synthesis and secretion of non-collagenous proteins by odontoblasts, thus resulting in the deposition of tertiary dentine. In this study, the effect of cavity preparation on osteonectin expression was examined in odontoblasts of the rat tooth pulp. A class V cavity was prepared in rat first molars to stimulate odontoblastic secretory activity, and the animals were killed at various intervals. In the normal pulp, osteonectin immunoreactivity was detected in odontoblasts but not other cells. At 1 day after cavity preparation, immunoreactivity had diminished beneath the cavity. At 3 days, strong immunoreactivity could be detected in odontoblasts beneath the cavity. Numerous round cells underlying the odontoblastic layer also demonstrated immunoreactivity. Thereafter, the intensity of osteonectin immunoreactivity in odontoblasts beneath tertiary dentine decreased gradually, and at 30 and 60 days, it was weaker than in normal pulp. These findings suggest that osteonectin is actively synthesized by odontoblasts underlying a cavity in the initial stage of tertiary dentine formation.
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Affiliation(s)
- T Itota
- Department of Operative Dentistry, Okayama University Dental School, 2-5-1 Shikata-cho, 700-8525, Okayama, Japan.
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30
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Kondo S, Tamura Y, Bawden JW, Tanase S. The immunohistochemical localization of Bax and Bcl-2 and their relation to apoptosis during amelogenesis in developing rat molars. Arch Oral Biol 2001; 46:557-68. [PMID: 11311203 DOI: 10.1016/s0003-9969(00)00139-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Bax and Bcl-2 are members of a family of intracellular, membrane-associated proteins that regulate programmed cell death. It has been suggested that, when Bax predominates, programmed cell death is accelerated and the apoptosis inhibitory activity of Bcl-2 is suppressed. The present study was undertaken to immunohistochemically (IHC) localize Bax and Bcl-2 in the cells of the enamel organ during amelogenesis in rat molars. Also, apoptotic cells were detected by TUNEL staining. The IHC intense localization of Bcl-2 and light staining for Bax in the pre-ameloblasts suggest that apoptosis is inhibited in the proliferating pre-ameloblasts. This is consistent with an absence of TUNEL staining for apoptosis in these cells. However, in the late secretory and transition ameloblasts, and adjacent stratum intermedium, evidence of apoptosis of the ameloblasts was observed. Bax and Bcl-2 were co-localized in the proximal ends of late secretory, transition and early maturation-stage ameloblasts, but immunoreactivity for Bax markedly increased in the proximal ends of late secretory and transition ameloblasts, while the Bcl-2 staining appeared to be lighter. This suggests that Bax antagonized Bcl-2 function, limiting the ability of Bcl-2 to prolong cell survival. In the early maturation stage, Bax staining faded while the immunoreactivity for Bcl-2 increased. Evidence of distinct apoptosis was reduced in the early maturation stage ameloblasts. When related to the occurrence of apoptosis during amelogenesis, the relative intensity of expression of Bax and Bcl-2 changed in a pattern consistent with that observed in other cell lines. This indicates that these proteins play essential roles in the process of amelogenesis, as predicted by their proposed mechanisms of action in the control of apoptosis.
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Affiliation(s)
- S Kondo
- The Department of Pediatric Dentistry, Asahi University School of Dentistry, 1851-1 501-0296, Hozumi Motosu Gifu, Japan
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31
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Kitamura C, Kimura K, Nakayama T, Toyoshima K, Terashita M. Primary and secondary induction of apoptosis in odontoblasts after cavity preparation of rat molars. J Dent Res 2001; 80:1530-4. [PMID: 11499507 DOI: 10.1177/00220345010800061001] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The death regulation of damaged pulp cells after cavity preparation is not well-known. In this study, we examined whether apoptosis is associated with the death regulation of damaged pulp cells. In normal rat molars, terminal deoxynucleotidyl transferase-mediated labeling (TUNEL)-positive cells were not observed. Just after surgery, odontoblasts under cavities were TUNEL-positive, and these signals disappeared in six hours. One day after surgery, we found the reappearance of TUNEL-positive cells in the subodontoblastic region under cavities, and positive signals disappeared in four days. Ultrastructure of TUNEL-positive cells showed characteristics typical of apoptotic cells. Phagocytosis of apoptotic cells by scavenger cells was also observed. By immunohistochemistry, we also found Bcl-2-positive odontoblasts one day after surgery. These results suggest that two waves of apoptosis are induced in odontoblasts after cavity preparation, and that apoptotic cells must be eliminated before the initiation of reparative dentinogenesis.
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Affiliation(s)
- C Kitamura
- Department of Operative Dentistry, Kyushu Dental College, Kitakyushu, Japan.
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32
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Rana MW, Pothisiri V, Killiany DM, Xu XM. Detection of apoptosis during orthodontic tooth movement in rats. Am J Orthod Dentofacial Orthop 2001; 119:516-21. [PMID: 11343024 DOI: 10.1067/mod.2001.113654] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Experimental evidence suggests that cellular changes and tissue turnover occurs in the periapical tissue during tooth movement. The possible role of apoptosis in tooth movement has never been investigated. The purpose of this study was to show whether apoptosis plays any role in orthodontic tooth movement. A sample of 21 adult male Sprague-Dawley rats was divided into 4 groups. Orthodontic appliances were attached to the rats for various times-to group I (n = 6) for 3 days, to group II (n = 6) for 1 week, and to group III (n = 6) for 2 weeks. Rats in group IV (n = 3) had appliances but no force and served as the control group. At the end of the observation period, the animals were killed and tissue blocks of involved teeth were processed and prepared for TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) reaction. TUNEL-positive cells from selected areas on each slide were counted and compared by means of an analysis of variance. Group I demonstrated a significantly higher (P <.05) number of positive cells. This suggests that the maximum apoptosis occurs approximately 3 days after the application of the appliance.
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Affiliation(s)
- M W Rana
- Department of Anatomy and Neurobiology, Saint Louis University School of Medicine, 1402 South Grand Blvd., St. Louis, MO 63104, USA.
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33
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Abstract
Development of the periodontium involves a series of complex steps that result in the formation of root dentine, cementum, bone and fibres of the ligament. These precisely controlled and timed events require the participation of the enamel organ derived epithelial cells of Hertwig's (HRS) and ectomesenchymal cells of the dental follicle. These events involve rapid turnover of the tissues and cells, including disappearance of epithelial cells of HRS. Thus, it seemed likely to us that programmed cell death (apoptosis) may play a role in the development of the periodontium. Fragments of first molars, obtained from 14- and 29-day-old rats, were fixed in glutaraldehyde-formaldehyde and processed for light and electron microscopy. For the TUNEL method for detection of apoptosis, specimens were fixed in 4% formaldehyde and embedded in paraffin. Results confirmed that epithelial cells of HRS maintain a close relationship with the forming dentine root, and that they may become trapped in the dentino-cemental junction. Some of the epithelial cells exhibited ultrastructural features which are consistent with the interpretation that they were undergoing programmed cell death, i.e. apoptosis. Periodontal fibroblast-like cells showed typical images of apoptosis and engulfed apoptotic bodies. TUNEL positive structures were present in all corresponding regions. It seems therefore that apoptosis of epithelial cells of HRS and fibroblast-like cells of the periodontal ligament constitutes an integral part of the developmental process of the tissues of the periodontium.
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Affiliation(s)
- P S Cerri
- Department of Morphology, São Paulo State University (UNESP), São Paulo, Brazil
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34
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Lyaruu DM, van Croonenburg EJ, van Duin MA, Bervoets TJ, Wöltgens JH, de Blieck-Hogervorst JM. Development of transplanted pulp tissue containing epithelial sheath into a tooth-like structure. J Oral Pathol Med 1999; 28:293-6. [PMID: 10432194 DOI: 10.1111/j.1600-0714.1999.tb02043.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aim of these studies was to find out whether intact neonatal pulp tissue containing residual epithelial cells can induce the development of a tooth-like structure in situ. First maxillary neonatal hamster molar pulps containing adhering undifferentiated epithelial cells were transplanted submucosally in the oral cavity of recipient mothers for periods ranging from 2-8 weeks and the tissues were then processed for light microscopy. Developing tooth-like structures containing mineralised tubular dentine, predentine and a vascularised pulp-like chamber lined with functional odontoblast-like cells were observed in the specimens within 2 weeks of transplantation. Enamel and root formation were not observed. These data indicate that neonatal dental pulp tissues containing epithelial cell remnants have the capacity to develop into tooth-like structures and that this could be the explanation for the development of tooth-like structures sometimes observed in infants after extraction of a natal tooth.
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Affiliation(s)
- D M Lyaruu
- Department of Oral Cell Biology, ACTA, Vrije Universiteit, Amsterdam, The Netherlands
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35
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Nishikawa S, Sasaki F. Apoptosis of dental pulp cells and their elimination by macrophages and MHC class II-expressing dendritic cells. J Histochem Cytochem 1999; 47:303-12. [PMID: 10026233 DOI: 10.1177/002215549904700304] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Apoptosis of dental pulp cells of rat incisors was investigated by the TUNEL method and electron microscopy. The results showed that a considerable amount of apoptosis occurred in the pulp, increasing in extent with incisal direction. OX6, ED1, and ED2 antibodies were used to detect macrophages and dendritic cells in combination with immunoelectron microscopy. Apoptotic fragments were eliminated mainly by MHC Class II-expressing cells, including dendritic cells positive for the OX6 antibody, and by MHC Class II-negative macrophages. Macrophages and dendritic cells positive for OX6, ED1, or ED2 increased from the apical to incisal direction of the incisor. These results indicate that apoptosis contributes to normal pulp formation and maintenance.
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Affiliation(s)
- S Nishikawa
- Department of Biology, Tsurumi University School of Dental Medicine, Yokohama, Japan.
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Otsuji W, Tanase S, Yoshida S, Bawden JW. The immunohistochemical localization of the interferon-gamma and granulocyte colony-stimulating factor receptors during early amelogenesis in rat molars. Arch Oral Biol 1999; 44:173-81. [PMID: 10206335 DOI: 10.1016/s0003-9969(98)00092-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Previous studies, in which the known janus kinase and signal transducer and activator of transcription (STAT) isoforms were immunohistochemically mapped in developing rat molars, implicated a sizeable list of cytokine superfamily receptor (CSR)/signal-transduction pathway (STP) linkages in the cells of the enamel organ involved in the events leading directly to early amelogenesis. Various combinations of upregulated janus kinases and STATs are known to be linked to single or small groups of CSRs. On the basis of the previous observations it was hypothesized that the interferon-gamma receptor (IFNgamma r) and the granulocyte colony-stimulating factor receptor (G-CSF receptor) would be localized in specific sites in the cells of the enamel organ during early amelogenesis. To verify this, whole-head, freeze-dried sections were here obtained at the level of the mandibular first and second molar from newborn and 5-day-old rats. These sections were not demineralized or fixed, reducing the possibility of false-negative results. Antibodies to the IFNgamma r and the G-CSF receptor were localized using a modification of the avidin-biotin complex method. In the newborn rats, IFNgamma r was localized in the preameloblasts in the cervical loop, the proximal and distal ends of presecretory ameloblasts, the outer enamel epithelium, the dental lamina, and in bone. In 5-day-old rats, it was confined to the proximal ends of the presecretory and secretory ameloblasts. The G-CSF receptor was observed in the molars of newborn rats in the preameloblasts, the proximal and distal ends of the presecretory ameloblasts, outer enamel epithelium, and in bone. In 5-day-old rats, G-CSF receptor was localized in the preameloblasts, the proximal ends of presecretory and secretory ameloblasts, the stellate reticulum, the outer enamel epithelium, and in bone. These findings indicate that the IFNgamma r and the G-CSF receptor, and their downstream STP linkages, are upregulated in the cells of the enamel organ and may be involved in the events leading directly to early enamel formation.
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Affiliation(s)
- W Otsuji
- The Department of Pediatric Dentistry, Asahi University School of Dentistry, Motosu, Gifu, Japan
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Lyaruu DM, van Duin MA, Bervoets TJ, Wöltgens JH, Bronckers AL. Effects of actinomycin D on developing hamster molar tooth germs in vitro. Eur J Oral Sci 1997; 105:52-8. [PMID: 9085029 DOI: 10.1111/j.1600-0722.1997.tb00180.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The aim of this study was to evaluate the toxic effects of actinomycin D on the developing hamster tooth germ in organ culture. Hamster tooth germs during early secretory amelogenesis were exposed in vitro for 24 h to 10(-9) M-5 x 10(-5) M actinomycin D. Actinomycin D dose-dependently (> or = 10(-7) M) decreased the tooth germ dry weight but mineralization was affected only by doses > or = 10(-5) M. However, the uptakes of TCA-insoluble 32P and [3H]thymidine were significantly reduced dose-dependently from > or = 10(-8) M actinomycin D, indicating that the drug inhibits the synthesis of phosphate-containing macromolecules as well as DNA synthesis. Histologically, 10(-8) M actinomycin D was the lowest dose which was not toxic to any cell type in the developing tooth germ. At 10(-7) M actinomycin D, the most sensitive cells were the proliferating pre-odontoblasts followed by pre-ameloblasts; the mature secretory ameloblasts and odontoblasts appeared unaffected. Higher doses resulted in increased cytotoxicity to the secretory cells and, eventually, total degeneration of most cells. The data suggest that children treated for cancer during tooth development using anti-chemotherapy cocktails containing actinomycin D (serum levels > 10(-7) M) may develop defects later on in the mature dentition as a direct consequence of the toxicity of the drug to the tooth organ.
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Affiliation(s)
- D M Lyaruu
- Dept. Oral Cell Biol., ACTA-Vrije Universiteit, Amsterdam, The Netherlands.
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Bronckers AL, Goei W, Luo G, Karsenty G, D'Souza RN, Lyaruu DM, Burger EH. DNA fragmentation during bone formation in neonatal rodents assessed by transferase-mediated end labeling. J Bone Miner Res 1996; 11:1281-91. [PMID: 8864903 DOI: 10.1002/jbmr.5650110913] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To study the fate of bone cells, we used the transferase-mediated, biotin-dUTP nick end-labeling (TUNEL) assay to detect DNA fragmentation during the formation of intramembranous and endochondral bone in newly born hamsters, mice, and rats. In alveolar bone forming around the developing tooth crowns, DNA fragmentation was found in three cell types: TRAP-negative mononuclear cells at the bone surface, osteocytes, and some but not all nuclei of TRAP-positive osteoclasts. Osteoblasts did not undergo DNA fragmentation. A strong positive correlation was found between contacts of TUNEL-positive osteocytes and osteoclasts. Extracellular bone matrix also stained occasionally for the presence of DNA fragments. During endochondral bone formation, TUNEL staining was detected in late hypertrophic chondrocytes of the epiphyseal growth plate. During rapid longitudinal growth of long bones, TUNEL-positive hypertrophic chondrocytes were found coincident with or slightly after invasion of blood vessels from the diaphysis. However, during slow longitudinal growth and in secondary ossification centers, DNA fragmentation was seen in hypertrophic chondrocytes still located within their lacunae. We conclude that some of the osteocytes in deeper layers of bone die within their lacuna and disperse nuclear fragments over the extracellular matrix, that a majority of the osteocytes are phagocytosed and degraded by osteoclasts at sites of intense bone resorption, and that during endochondral ossification, substantial numbers of late hypertrophic chondrocyte cells undergo cell death.
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Affiliation(s)
- A L Bronckers
- Department of Oral Cell Biology ACTA, Vrije Universiteit, Amsterdam, The Netherlands
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