When patterns are set during embryogenesis, it is expected that they are straightly established rather than subsequently modified. The patterning of the three mouse molars is, however, far from straight, likely as a result of mouse evolutionary history. The first-formed tooth signaling centers, called MS and R2, disappear before driving tooth formation and are thought to be vestiges of the premolars found in mouse ancestors. Moreover, the mature signaling center of the first molar (M1) is formed from the fusion of two signaling centers (R2 and early M1). Here, we report that broad activation of Edar expression precedes its spatial restriction to tooth signaling centers. This reveals a hidden two-step patterning process for tooth signaling centers, which was modeled with a single activator-inhibitor pair subject to reaction-diffusion (RD). The study of Edar expression also unveiled successive phases of signaling center formation, erasing, recovering, and fusion. Our model, in which R2 signaling center is not intrinsically defective but erased by the broad activation preceding M1 signaling center formation, predicted the surprising rescue of R2 in Edar mutant mice, where activation is reduced. The importance of this R2-M1 interaction was confirmed by ex vivo cultures showing that R2 is capable of forming a tooth. Finally, by introducing chemotaxis as a secondary process to RD, we recapitulated in silico different conditions in which R2 and M1 centers fuse or not. In conclusion, pattern formation in the mouse molar field relies on basic mechanisms whose dynamics produce embryonic patterns that are plastic objects rather than fixed end points.
- MeSH
- Models, Biological * MeSH
- Chemotaxis MeSH
- Epithelium embryology metabolism MeSH
- Mice, Mutant Strains MeSH
- Mice MeSH
- Edar Receptor genetics metabolism MeSH
- Body Patterning * MeSH
- Signal Transduction * MeSH
- Hair embryology MeSH
- Gene Expression Regulation, Developmental MeSH
- Tooth Germ embryology metabolism MeSH
- Tooth embryology metabolism MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The purpose of the study was to test the hypothesis of different distribution spaces of elements in the rat mandibular bone and teeth. We used six adult males of Wistar laboratory rats for the study. After killing the animals, we extracted the molars and removed incisor crowns. The mandibular bone was divided into four parts (mesial-central-distal-ridge). Inductively coupled plasma mass spectrometry was used to determine the presence of 41 elements in the bone and tooth. Evidence of 14 elements was found in all samples (incisors-molarsbone). Generally, significant differences between the left and right side were found for K and Rb in the bone locations. As regards statistically significant differences in incisors-molars-bone locations, the elements for which these differences were found for all comparisons are listed as incisors versus individual molars, incisors versus bone locations, and individual molars versus bone locations: a) incisors-molars: Ba, Mn, Mo, Sr, Zn, K, Mg and Rb; b) incisors-bone: Fe, K, Mg, Mn, Na, Zn and Ba; c) molars-bone: Mn, Mo, Na and Mg. Statistically significant differences were also found between molars for Fe, Mg, Mn, and Sr and between bone locations for Ba, Ca, Mn, Sr, K, Rb, Zn, Mo, Mg, and Na. The elements Cu, Ni and Co were without pronounced differences. Twenty-seven elements were below the detection limit. Our results indicate different distributions of some elements in the rat mandibular incisors-molars-bone. We assume that the knowledge of chemical element contents in the laboratory rat bone and teeth will prove useful in experimental research of both these hard tissues.
- MeSH
- Analysis of Variance MeSH
- Mandible metabolism MeSH
- Rats, Wistar MeSH
- Elements * MeSH
- Tooth metabolism MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Teeth develop within the surrounding periodontal tissues, involving the alveolar bone, periodontal ligament and cementum. The alveolar bone originates through the process of intramembranous ossification involving mesenchymal cells from the tooth germ. As most available data are related to endochondral ossification, we examined the molecular background of alveolar bone development. We investigated the osteogenic profile of mesenchymal cells dissected from mouse mandible slices at the stage of early alveolar bone formation. Relative monitoring of gene expression was undertaken using PCR Arrays; this included the profiles of 84 genes associated with osteogenesis. To examine the tooth-bone interface, stages with detectable changes in bone remodelling during development (E13.0, E14.0 and E15.0) were chosen and compared with each other. These results showed a statistically significant increase in the expression of the genes Fgf3, Ctsk, Icam-1, Mmp9, Itga3 and Tuft1, and of a wide range of collagens (Col1a2, Col3a1, Col7a1, Col12a1, Col14a1). Decreased expression was detected in the case of Col2a1, Sox9, Smad2 and Vegfb. To confirm these changes in gene expression, immunofluorescence analyses of Mmp9 and Sox9 proteins were performed in situ. Our research has identified several candidate genes that may be crucial for the initiation of alveolar bone formation and is the basis for further functional studies.
- MeSH
- Collagen metabolism MeSH
- Mesenchymal Stem Cells cytology MeSH
- Mice MeSH
- Osteogenesis physiology MeSH
- Periodontal Ligament metabolism MeSH
- Bone Development physiology MeSH
- Gene Expression Regulation, Developmental MeSH
- Tooth Germ embryology metabolism MeSH
- Tooth cytology embryology metabolism MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Teeth have been a focus of interest for many centuries--due to medical problems with them. They are the hardest part of the human body and are composed of three mineralized parts--enamel, dentin and cementum, together with the soft pulp. However, saliva also has a significant impact on tooth quality. Proteomic research of human teeth is now accelerating, and it includes all parts of the tooth. Some methodological problems still need to be overcome in this research field--mainly connected with calcified tissues. This review will provide an overview of the current state of research with focus on the individual parts of the tooth and pellicle layer as well as saliva. These proteomic results can help not only stomatology in terms of early diagnosis, identifying risk factors, and systematic control.
- MeSH
- Humans MeSH
- Proteome metabolism MeSH
- Proteomics methods MeSH
- Saliva metabolism MeSH
- Gene Expression Profiling methods MeSH
- Tissue Distribution MeSH
- Tooth metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
The transcription factor c-Myb is involved in the control of cell proliferation, survival and differentiation. As these processes accompany the morphogenesis of developing teeth, this work investigates the possible role of c-Myb during odontogenesis. Analysis of the expression of c-Myb in the monophyodont mouse was followed by similar analysis in a diphyodont species, the pig, which has a dentition more closely resembling that of the human. The distribution of c-Myb was correlated with the pattern of proliferation and apoptosis and the tooth phenotype of c-Myb mutant mice was also assessed. In the mouse, c-Myb expression was detected throughout prenatal development of the first molar tooth. Negative temporospatial correlation was found between c-Myb expression and apoptosis, while c-Myb expression positively correlated with proliferation. c-Myb-positive cells, however, were more abundant than the proliferating cell nuclear antigen positive cells, suggesting other roles of c-Myb in odontogenesis. In the minipig, in contrast to the mouse, there was an asymmetrical arrangement of c-Myb positive cells, with a higher presence on the labial side of the tooth germ and dental lamina. A cluster of negative cells was situated in the mesenchyme close to the tooth bud. At later stages, the number of positive cells decreased and these cells were situated in the upper part of the dental papilla in the areas of future cusp formation. The expression of c-Myb in both species was strong in the odontoblasts and ameloblasts at the stage of dentin and enamel production suggesting a possible novel role of c-Myb during tooth mineralization.
- MeSH
- Alleles MeSH
- Ameloblasts cytology metabolism MeSH
- Apoptosis MeSH
- Dentition MeSH
- Species Specificity MeSH
- Embryo, Mammalian cytology embryology metabolism MeSH
- Immunohistochemistry MeSH
- Cloning, Molecular MeSH
- In Situ Nick-End Labeling MeSH
- Swine, Miniature MeSH
- Mice MeSH
- Odontoblasts cytology metabolism MeSH
- Odontogenesis MeSH
- Osteoclasts cytology metabolism MeSH
- Swine MeSH
- Cell Proliferation MeSH
- Proliferating Cell Nuclear Antigen metabolism MeSH
- Cell Cycle Proteins genetics metabolism MeSH
- Proto-Oncogene Proteins c-myb genetics metabolism MeSH
- Trans-Activators genetics metabolism MeSH
- Gene Expression Regulation, Developmental MeSH
- Tooth cytology embryology metabolism MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- MeSH
- Rats MeSH
- Lactate Dehydrogenases metabolism MeSH
- Tetracyclines adverse effects MeSH
- Tooth metabolism MeSH
- Check Tag
- Rats MeSH
- MeSH
- Dentinogenesis MeSH
- Phosphorus metabolism MeSH
- Cariogenic Agents pharmacology MeSH
- Cariostatic Agents pharmacology MeSH
- Bone and Bones metabolism MeSH
- Animal Feed MeSH
- Rats MeSH
- Odontogenesis MeSH
- Osteogenesis MeSH
- Pregnancy, Animal MeSH
- Pregnancy MeSH
- Calcium metabolism MeSH
- Dental Caries etiology MeSH
- Tooth metabolism MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Pregnancy MeSH
- Female MeSH
- Animals MeSH
