BMP4 rescues a non-cell-autonomous function of Msx1 in tooth development

Development ◽  
2000 ◽  
Vol 127 (21) ◽  
pp. 4711-4718 ◽  
Author(s):  
M. Bei ◽  
K. Kratochwil ◽  
R.L. Maas
Keyword(s):  
Dental Pulp ◽  
Tooth Development ◽  
Survival Function ◽  
Tooth Germ ◽  
Tooth Formation ◽  
Kidney Capsule ◽  
Dependent Signal ◽  
Dental Epithelium ◽  
Tooth Germs

The development of many organs depends on sequential epithelial-mesenchymal interactions, and the developing tooth germ provides a powerful model for elucidating the nature of these inductive tissue interactions. In Msx1-deficient mice, tooth development arrests at the bud stage when Msx1 is required for the expression of Bmp4 and Fgf3 in the dental mesenchyme (Bei, M. and Maas, R. (1998) Development 125, 4325–4333). To define the tissue requirements for Msx1 function, we performed tissue recombinations between wild-type and Msx1 mutant dental epithelium and mesenchyme. We show that through the E14.5 cap stage of tooth development, Msx1 is required in the dental mesenchyme for tooth formation. After the cap stage, however, tooth development becomes Msx1 independent, although our experiments identify a further late function of Msx1 in odontoblast and dental pulp survival. These results suggest that prior to the cap stage, the dental epithelium receives an Msx1-dependent signal from the dental mesenchyme that is necessary for tooth formation. To further test this hypothesis, Msx1 mutant tooth germs were first cultured with either BMP4 or with various FGFs for two days in vitro and then grown under the kidney capsule of syngeneic mice to permit completion of organogenesis and terminal differentiation. Previously, using an in vitro culture system, we showed that BMP4 stimulated the growth of Msx1 mutant dental epithelium (Chen, Y., Bei, M. Woo, I., Satokata, I. and Maas, R. (1996). Development 122, 3035–3044). Using the more powerful kidney capsule grafting procedure, we now show that when added to explanted Msx1-deficient tooth germs prior to grafting, BMP4 rescues Msx1 mutant tooth germs all the way to definitive stages of enamel and dentin formation. Collectively, these results establish a transient functional requirement for Msx1 in the dental mesenchyme that is almost fully supplied by BMP4 alone, and not by FGFs. In addition, they formally prove the postulated downstream relationship of BMP4 with respect to Msx1, establish the non-cell-autonomous nature of Msx1 during odontogenesis, and disclose an additional late survival function for Msx1 in odontoblasts and dental pulp.

Localization of Nerve Cells in the Developing Rat Tooth

1997 ◽  
Vol 76 (7) ◽  
pp. 1350-1356 ◽  
Author(s):  
K. Luukko ◽  
K. Sainio ◽  
H. Sariola ◽  
M. Saarma ◽  
I. Thesleff
Keyword(s):  
Neuronal Cells ◽  
Neuronal Cell ◽  
Tooth Germ ◽  
Nerve Fibers ◽  
Tooth Formation ◽  
Neuronal Cell Bodies ◽  
Dental Epithelium ◽  
Tooth Germs ◽  
Developing Rat

Earlier studies have shown that mammalian tooth formation can take place in the absence of peripheral nerve fibers. This has been taken to indicate that neurons are not needed for mammalian tooth development. However, our recent localization of peripherin, which is a neuronal cell marker, has suggested that neuronal cell bodies may be associated with developing teeth. In this study, we have analyzed in vivo and in vitro the presence of neuronal cells in developing rat tooth germs. When E14 and E16 rat first molars (thickening of presumptive dental epithelium and bud-stage tooth germ, respectively) were cultured in vitro, peripheral trigeminal axons degenerated. However, with antibodies against peripherin and L1 neural cell adhesion protein, we detected neuronal cell bodies and their axons in the explants. Next, the expression of neurofilament light-chain (NF-L) mRNAs was studied by in situ hybridization of embryonic E12 first branchial arches and tooth germs from initiation to completion of crown morphogenesis (E13, five-day post-natal teeth). NF-L transcripts were first seen at the bud stage (E15) next to the dental epithelium at the buccal side of the tooth germ. At the cap stage (E18), NF-L mRNAs were located under the oral epithelium at some distance from dental epithelium. These expression patterns correlate to the previous localization of peripherin-positive cells and suggest that NF-L expression also revealed neuronal cells. Taken together, these results demonstrate that, in addition to projections of peripheral neurons, neuronal cells are associated with the developing teeth. Hence, it is possible that neuronal cells may participate in the regulation of mammalian tooth formation.

scholarly journals Expression, localization and synthesis of small leucine-rich proteoglycans in developing mouse molar tooth germ

2020 ◽  
Vol 64 (1) ◽  
Author(s):  
Angammana Randilini ◽  
Kaoru Fujikawa ◽  
Shunichi Shibata
Keyword(s):  
Organ Culture ◽  
Developmental Stages ◽  
Tooth Development ◽  
Expression Patterns ◽  
Tooth Germ ◽  
Molar Tooth ◽  
Cervical Region ◽  
Metabolic Labeling ◽  
Tooth Formation ◽  
Tooth Germs

The gene expression and protein synthesis of small leucine-rich proteoglycans (SLRPs), including decorin, biglycan, fibromodulin, and lumican, was analyzed in the context of the hypothesis that they are closely related to tooth formation. In situ hybridization, immunohistochemistry, and organ culture with metabolic labeling of [35S] were carried out in mouse first molar tooth germs of different developmental stages using ICR mice at embryonic day (E) 13.5 to postnatal day (P) 7.0. At the bud and cap stage, decorin mRNA was expressed only in the surrounding mesenchyme, but not within the tooth germ. Biglycan mRNA was then expressed in the condensing mesenchyme and the dental papilla of the tooth germ. At the apposition stage (late bell stage), both decorin and biglycan mRNA were expressed in odontoblasts, resulting in a switch of the pattern of expression within the different stages of odontoblast differentiation. Decorin mRNA was expressed earlier in newly differentiating odontoblasts than biglycan. With odontoblast maturation and dentin formation, decorin mRNA expression was diminished and localized to the newly differentiating odontoblasts at the cervical region. Simultaneously, biglycan mRNA took over and extended its expression throughout the new and mature odontoblasts. Both mRNAs were expressed in the dental pulp underlying the respective odontoblasts. At P7.0, both mRNAs were weakly expressed but maintained their spatial expression patterns. Immunostaining showed that biglycan was localized in the dental papillae and pulp. In addition, all four SLRPs showed clear immunostaining in predentin, although the expressions of fibromodulin and lumican mRNAs were not identified in the tooth germs examined. The organ culture data obtained supported the histological findings that biglycan is more predominant than decorin at the apposition stage. These results were used to identify biglycan as the principal molecule among the SLRPs investigated. Our findings indicate that decorin and biglycan show spatial and temporal differential expressions and play their own tissue-specific roles in tooth development.

scholarly journals Morphometric Approach to Pulp Fibroblast Development in Tooth Germ

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Irina-Draga Căruntu ◽  
Sergiu Daniel Săvinescu ◽  
Cornelia Amălinei
Keyword(s):  
Form Factor ◽  
Dental Pulp ◽  
Tooth Development ◽  
Tooth Germ ◽  
Mean Value ◽  
Relative Distance ◽  
Color Segmentation ◽  
Histological Criteria ◽  
The Individual ◽  
Tooth Germs

This paper builds a morphometric framework for the analysis of dental pulp fibroblast evolution during tooth development. We investigated 15 tooth germs (cases) organized, by histological criteria, in three groups corresponding to cap, early bell, and late bell stages, respectively. Each group comprised five cases. The morphometric description used the following parameters: areaA, perimeterP—automatically extracted by a color segmentation technique, and form factor (FF)—calculated as4πA/P2. The designed framework operated at inter- and intragroup levels. The intergroup analysis quantified the differences between groups, in the sense of a relative distance (RD) adequately defined by mean-value scaling. We showed that the stage of early bell is approximately 5 times closer to late bell than to cap. The quantification procedure required concomitant information aboutA,Pparameters (asP versus Adependences, orFFvalues), whereas the procedure failed forAorPseparately used. The intragroup analysis quantified the similarity of the cases belonging to the same stage. We proved that, unlike the intergroup tests, the individual exploitation of all three descriptorsA,P, andFFis effective, yielding highly compatible results. Within any group, most cases presented RDs less than 10% from the group mean value, regardless of the descriptor type.

Epithelial-mesenchymal interactions are required for msx 1 and msx 2 gene expression in the developing murine molar tooth

Development ◽  
1993 ◽  
Vol 117 (2) ◽  
pp. 461-470 ◽  
Author(s):  
A.K. Jowett ◽  
S. Vainio ◽  
M.W. Ferguson ◽  
P.T. Sharpe ◽  
I. Thesleff
Keyword(s):  
Gene Expression ◽  
Tooth Development ◽  
Homeobox Gene ◽  
Oral Epithelium ◽  
Tooth Formation ◽  
Dental Papilla ◽  
Tissue Interactions ◽  
Dental Epithelium

Duplication of the msh-like homeobox gene of Drosophila may be related to the evolution of the vertebrate head. The murine homologues of this gene, msx 1 and msx 2 are expressed in the developing craniofacial complex including the branchial arches, especially in regions of epithelial-mesenchymal organogenesis including the developing tooth. By performing in vitro recombination experiments using homochronic dental and non-dental epithelial and mesenchymal tissues from E10 to E18 mouse embryos, we have found that the maintenance of homeobox gene expression in the tooth is dependent upon tissue interactions. In homotypic recombinants, dental-type tissue interactions occur, leading to expression of both genes in a manner similar to that seen during in vivo development. msx 1 is expressed exclusively in mesenchyme, both in the dental papilla and follicle. msx 2 is expressed in the dental epithelium and only in the mesenchyme of the dental papilla. In heterotypic recombinants, the dental epithelium is able to induce msx 1 expression in non-dental mesenchyme, this potential being lost at the bell stage. In these recombinants msx 2 was induced by presumptive dental epithelium prior to the bud stage but not thereafter. The expression of msx 1 and msx 2 in dental mesenchyme requires the presence of epithelium until the early bell stage. However, whereas non-dental, oral epithelium is capable of maintaining expression of msx 1 in dental mesenchyme throughout tooth development, induction of msx 2 was temporally restricted suggesting regulation by a specific epithelial-mesenchymal interaction related to the inductive events of tooth formation. msx 1 and msx 2, as putative transcription factors, may play a role in regulating the expression of other genes during tooth formation. We conclude that expression of msx 1 in jaw mesenchyme requires a non-specific epithelial signal, whereas msx 2 expression in either epithelium or mesenchyme requires reciprocal interactions between specialized dental cell populations.

scholarly journals Insight into the maintenance of odontogenic potential in mouse dental mesenchymal cells based on transcriptomic analysis

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1684 ◽  
Author(s):  
Yunfei Zheng ◽  
Lingfei Jia ◽  
Pengfei Liu ◽  
Dandan Yang ◽  
Waner Hu ◽  
...  
Keyword(s):  
Tooth Development ◽  
Differential Expression Analysis ◽  
Mesenchymal Cells ◽  
Genes Encoding ◽  
Dental Epithelium ◽  
Wnt Pathways ◽  
Tooth Germs ◽  
Insight Into

Background.Mouse dental mesenchymal cells (mDMCs) from tooth germs of cap or later stages are frequently used in the context of developmental biology or whole-tooth regeneration due to their odontogenic potential.In vitro-expanded mDMCs serve as an alternative cell source considering the difficulty in obtaining primary mDMCs; however, cultured mDMCs fail to support tooth development as a result of functional failures of specific genes or pathways. The goal of this study was to identify the genes that maintain the odontogenic potential of mDMCs in culture.Methods.We examined the odontogenic potential of freshly isolated versus cultured mDMCs from the lower first molars of embryonic day 14.5 mice. The transcriptome of mDMCs was detected using RNA sequencing and the data were validated by qRT-PCR. Differential expression analysis and pathway analysis were conducted to identify the genes that contribute to the loss of odontogenic potential.Results.Cultured mDMCs failed to develop into well-structured tooth when they were recombined with dental epithelium. Compared with freshly isolated mDMCs, we found that 1,004 genes were upregulated and 948 were downregulated in cultured mDMCs. The differentially expressed genes were clustered in the biological processes and signaling pathways associated with tooth development. Followingin vitroculture, genes encoding a wide array of components of MAPK, TGF-β/BMP, and Wnt pathways were significantly downregulated. Moreover, the activities ofBdnf,Vegfα,Bmp2, andBmp7were significantly inhibited in cultured mDMCs. Supplementation of VEGFα, BMP2, and BMP7 restored the expression of a subset of downregulated genes and induced mDMCs to form dentin-like structuresin vivo.Conclusions.Vegfα,Bmp2, andBmp7play a role in the maintenance of odontogenic potential in mDMCs.

scholarly journals BMP Activity Is Required for Tooth Development from the Lamina to Bud Stage

2012 ◽  
Vol 91 (7) ◽  
pp. 690-695 ◽  
Author(s):  
Y. Wang ◽  
L. Li ◽  
Y. Zheng ◽  
G. Yuan ◽  
G. Yang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Molecular Marker ◽  
Tooth Development ◽  
Tooth Germ ◽  
Bmp Signaling ◽  
Expression Of Genes ◽  
Dental Epithelium ◽  
Initiation Stage ◽  
Transgenic Embryos ◽  
Bmp Antagonist

Several Bmp genes are expressed in the developing mouse tooth germ from the initiation to the late-differentiation stages, and play pivotal roles in multiple steps of tooth development. In this study, we investigated the requirement of BMP activity in early tooth development by transgenic overexpression of the extracellular BMP antagonist Noggin. We show that overexpression of Noggin in the dental epithelium at the tooth initiation stage arrests tooth development at the lamina/early-bud stage. This phenotype is coupled with a significantly reduced level of cell proliferation rate and a down-regulation of Cyclin-D1 expression, specifically in the dental epithelium. Despite unaltered expression of genes known to be implicated in early tooth development in the dental mesenchyme and dental epithelium of transgenic embryos, the expression of Pitx2, a molecular marker for the dental epithelium, became down-regulated, suggesting the loss of odontogenic fate in the transgenic dental epithelium. Our results reveal a novel role for BMP signaling in the progression of tooth development from the lamina stage to the bud stage by regulating cell proliferation and by maintaining odontogenic fate of the dental epithelium.

scholarly journals A comparative study of the development in vivo and in vitro of rat and rabbit molars

1938 ◽  
Vol 126 (844) ◽  
pp. 315-330 ◽  
Keyword(s):  
Tooth Germ ◽  
The Body ◽  
Extrinsic Factors ◽  
Intrinsic Factors ◽  
Mammalian Teeth ◽  
Tooth Germs ◽  
Developmental Mechanics ◽  
General Influence

Although the normal embryology of mammalian teeth has been carefully studied, little is known of the developmental mechanics of teeth. The present communication is concerned with the problem of cusp formation. The main object of the investigation was to find how far the formation of molar cusps was due to extrinsic factors in the jaw and how far to intrinsic factors in the tooth germ itself. Previous work (Glasstone 1936) had shown that embryonic teeth grown in vitro and removed from the general influence of the body continue to develop. In these earlier experiments the rudiments were explanted when cusps had already appeared but before odontoblasts and dentine had differentiated. In the present experiments the tooth germs were explanted at an earlier stage before the cusps had begun to form, to see whether cusps would develop in vitro in the isolated rudiment and if so whether they would correspond in number, shape and arrangement with those of the normal embryonic tooth.

scholarly journals Smad7 Regulates Dental Epithelial Proliferation during Tooth Development

2019 ◽  
Vol 98 (12) ◽  
pp. 1376-1385 ◽  
Author(s):  
Z. Liu ◽  
T. Chen ◽  
D. Bai ◽  
W. Tian ◽  
Y. Chen
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cyclin D1 ◽  
Transforming Growth Factor ◽  
Tooth Development ◽  
Tooth Germ ◽  
Transforming Growth Factor Β ◽  
Tooth Size ◽  
Dental Epithelium ◽  
Tooth Morphogenesis

Tooth morphogenesis involves dynamic changes in shape and size as it proceeds through the bud, cap, and bell stages. This process requires exact regulation of cell proliferation and differentiation. Smad7, a general antagonist against transforming growth factor–β (TGF-β) signaling, is necessary for maintaining homeostasis and proper functionality in many organs. While TGF-β signaling is widely involved in tooth morphogenesis, the precise role of Smad7 in tooth development remains unknown. In this study, we showed that Smad7 is expressed in the developing mouse molars with a high level in the dental epithelium but a moderate to weak level in the dental mesenchyme. Smad7 deficiency led to a profound decrease in tooth size primarily due to a severely compromised cell proliferation capability in the dental epithelium. Consistent with the tooth shrinkage phenotype, RNA sequencing (RNA-seq) analysis revealed that Smad7 ablation downregulated genes referred to epithelial cell proliferation and cell cycle G1/S phase transition, whereas the upregulated genes were involved in responding to TGF-β signaling and cell cycle arrest. Among these genes, the expression of Cdkn1a (encoding p21), a negative cell proliferation regulator, was remarkably elevated in parallel with the diminution of Ccnd1 encoding the crucial cell cycle regulator cyclin D1 in the dental epithelium. Meanwhile, the expression level of p-Smad2/3 was ectopically elevated in the developing tooth germ of Smad7 null mice, indicating the hyperactivation of the canonical TGF-β signaling. These effects were reversed by addition of TGF-β signaling inhibitor in cell cultures of Smad7−/− molar tooth germs, with rescued expression of cyclin D1 and cell proliferation rate. In sum, our studies demonstrate that Smad7 functions primarily as a positive regulator of cell proliferation via inhibition of the canonical TGF-β signaling during dental epithelium development and highlight a crucial role for Smad7 in regulating tooth size.

TheHOX genes are expressed, in vivo, in human tooth germs: In vitro cAMP exposure of dental pulp cells results in parallel HOX network activation and neuronal differentiation

2006 ◽  
Vol 97 (4) ◽  
pp. 836-848 ◽  
Author(s):  
Vincenzo D'Antò ◽  
Monica Cantile ◽  
Maria D'Armiento ◽  
Giulia Schiavo ◽  
Gianrico Spagnuolo ◽  
...  
Keyword(s):  
Neuronal Differentiation ◽  
Dental Pulp ◽  
Human Tooth ◽  
Dental Pulp Cells ◽  
Network Activation ◽  
Pulp Cells ◽  
Tooth Germs

FGFs and BMP4 induce both Msx1-independent and Msx1-dependent signaling pathways in early tooth development

Development ◽  
1998 ◽  
Vol 125 (21) ◽  
pp. 4325-4333 ◽  
Author(s):  
M. Bei ◽  
R. Maas
Keyword(s):  
Signaling Pathways ◽  
Tooth Development ◽  
Signaling Molecules ◽  
Dependent Manner ◽  
Wild Type ◽  
Independent Manner ◽  
Dental Lamina ◽  
Bmp4 Expression ◽  
Dental Epithelium ◽  
Tooth Germs

During early tooth development, multiple signaling molecules are expressed in the dental lamina epithelium and induce the dental mesenchyme. One signal, BMP4, has been shown to induce morphologic changes in dental mesenchyme and mesenchymal gene expression via Msx1, but BMP4 cannot substitute for all the inductive functions of the dental epithelium. To investigate the role of FGFs during early tooth development, we examined the expression of epithelial and mesenchymal Fgfs in wild-type and Msx1 mutant tooth germs and tested the ability of FGFs to induce Fgf3 and Bmp4 expression in wild-type and Msx1 mutant dental mesenchymal explants. Fgf8 expression is preserved in Msx1 mutant epithelium while that of Fgf3 is not detected in Msx1 mutant dental mesenchyme. Moreover, dental epithelium as well as beads soaked in FGF1, FGF2 or FGF8 induce Fgf3 expression in dental mesenchyme in an Msx1-dependent manner. These results indicate that, like BMP4, FGF8 constitutes an epithelial inductive signal capable of inducing the expression of downstream signaling molecules in dental mesenchyme via Msx1. However, the BMP4 and FGF8 signaling pathways are distinct. BMP4 cannot induce Fgf3 nor can FGFs induce Bmp4 expression in dental mesenchyme, even though both signaling molecules can induce Msx1 and Msx1 is necessary for Fgf3 and Bmp4 expression in dental mesenchyme. In addition, we have investigated the effects of FGFs and BMP4 on the distal-less homeobox genes Dlx1 and Dlx2 and we have clarified the relationship between Msx and Dlx gene function in the developing tooth. Dlx1,Dlx2 double mutants exhibit a lamina stage arrest in maxillary molar tooth development (Thomas B. L., Tucker A. S., Qiu M., Ferguson C. A., Hardcastle Z., Rubenstein J. L. R. and Sharpe P. T. (1997) Development 124, 4811–4818). Although the maintenance of molar mesenchymal Dlx2 expression at the bud stage is Msx1-dependent, both the maintenance of Dlx1 expression and the initial activation of mesenchymal Dlx1 and Dlx2 expression during the lamina stage are not. Moreover, in contrast to the tooth bud stage arrest observed in Msx1 mutants, Msx1,Msx2 double mutants exhibit an earlier phenotype closely resembling the lamina stage arrest observed in Dlx1,Dlx2 double mutants. These results are consistent with functional redundancy between Msx1 and Msx2 in dental mesenchyme and support a model whereby Msx and Dlx genes function in parallel within the dental mesenchyme during tooth initiation. Indeed, as predicted by such a model, BMP4 and FGF8, epithelial signals that induce differential Msx1 and Msx2 expression in dental mesenchyme, also differentially induce Dlx1 and Dlx2 expression, and do so in an Msx1-independent manner. These results integrate Dlx1, Dlx2 and Fgf3 and Fgf8 into the odontogenic regulatory hierarchy along with Msx1, Msx2 and Bmp4, and provide a basis for interpreting tooth induction in terms of transcription factors which, individually, are necessary but not sufficient for the expression of downstream signals and therefore must act in specific combinations.

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