51
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Roles of dental development and adaptation in rodent evolution. Nat Commun 2013; 4:2504. [DOI: 10.1038/ncomms3504] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 08/23/2013] [Indexed: 01/25/2023] Open
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52
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Hovorakova M, Smrckova L, Lesot H, Lochovska K, Peterka M, Peterkova R. Sequential Shh expression in the development of the mouse upper functional incisor. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2013; 320:455-64. [PMID: 23913503 DOI: 10.1002/jez.b.22522] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 05/21/2013] [Accepted: 06/03/2013] [Indexed: 11/06/2022]
Abstract
The mouse incisor is a frequently used model in studies of the molecular control of organ development. The appropriate interpretation of data on normogenesis is essential for understanding the data obtained in mutant mice. For this reason, we performed a very detailed investigation of the development of the upper incisor in wild-type mice from embryonic day (ED) 11.5 till 14.5. A combination of histology, whole mount in situ hybridization, computer-aided three-dimensional reconstructions, and fluorescent microscopy, has been used. Several sonic hedgehog (Shh) expression domains have been detected in the upper incisor region during early prenatal development. At ED11.5-13.5, there was a single Shh positive domain present in the anterior part of left or right upper jaw arches, corresponding to the epithelial thickening. More posteriorly, a new Shh expression domain appeared in the incisor bud in the developmentally more advanced ED13.5 embryos. At ED14.5, only this posterior Shh expression in the incisor germ remained detectable. This study brings new insights into the early development of the upper incisor in mice and completes the data on normal mouse incisor development. The temporal-spatial pattern of Shh expression reflects the development of two tooth generations, being detectable in two successive, antero-posteriorly located areas in the prospective incisor region in the upper jaw. The first, anterior and superficial Shh expression domain reflects the rudimentary tooth development suppressed during evolution. Only the subsequent, posterior and deeper Shh expression region, appearing at ED13.5, correlates with the prospective upper functional incisor in wild-type mice.
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Affiliation(s)
- Maria Hovorakova
- Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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53
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Lagronova-Churava S, Spoutil F, Vojtechova S, Lesot H, Peterka M, Klein OD, Peterkova R. The dynamics of supernumerary tooth development are differentially regulated by Sprouty genes. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2013; 320:307-20. [PMID: 23606267 DOI: 10.1002/jez.b.22502] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 02/28/2013] [Accepted: 03/01/2013] [Indexed: 11/10/2022]
Abstract
In mice, a toothless diastema separates the single incisor from the three molars in each dental quadrant. In the prospective diastema of the embryo, small rudimentary buds are found that are presumed to be rudiments of suppressed teeth. A supernumerary tooth occurs in the diastema of adult mice carrying mutations in either Spry2 or Spry4. In the case of Spry2 mutants, the origin of the supernumerary tooth involves the revitalization of a rudimentary tooth bud (called R2), whereas its origin in the Spry4 mutants is not known. In addition to R2, another rudimentary primordium (called MS) arises more anteriorly in the prospective diastema. We investigated the participation of both rudiments (MS and R2) in supernumerary tooth development in Spry2 and Spry4 mutants by comparing morphogenesis, proliferation, apoptosis, size and Shh expression in the dental epithelium of MS and R2 rudiments. Increased proliferation and decreased apoptosis were found in MS and R2 at embryonic day (ED) 12.5 and 13.5 in Spry2(-/-) embryos. Apoptosis was also decreased in both rudiments in Spry4(-/-) embryos, but the proliferation was lower (similar to WT mice), and supernumerary tooth development was accelerated, exhibiting a cap stage by ED13.5. Compared to Spry2(-/-) mice, a high number of Spry4(-/-) supernumerary tooth primordia degenerated after ED13.5, resulting in a low percentage of supernumerary teeth in adults. We propose that Sprouty genes were implicated during evolution in reduction of the cheek teeth in Muridae, and their deletion can reveal ancestral stages of murine dental evolution.
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54
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Renaud S, Hardouin EA, Pisanu B, Chapuis JL. Invasive house mice facing a changing environment on the Sub-Antarctic Guillou Island (Kerguelen Archipelago). J Evol Biol 2013; 26:612-24. [PMID: 23331296 DOI: 10.1111/jeb.12079] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 10/16/2012] [Accepted: 11/19/2012] [Indexed: 11/26/2022]
Abstract
Adaptation to new environments is a key feature in evolution promoting divergence in morphological structures under selection. The house mouse (Mus musculus domesticus) introduced on the Sub-Antarctic Guillou Island (Kerguelen Archipelago) had and still has to face environmental conditions that likely shaped the pattern and pace of its insular evolution. Since mouse arrival on the island, probably not more than two centuries ago, ecological conditions dramatically differed from those available to their Western European commensal source populations. In addition, over the last two decades, the plant and animal communities of Guillou Island were considerably modified by the eradication of rabbits, the effects of climate change and the spread of invasive species detrimental to native communities. Under such a changing habitat, the mouse response was investigated using a morphometric quantification of mandible and molar tooth, two morphological structures related to food processing. A marked differentiation of the insular mice compared with their relatives from Western Europe was documented for both mandibles and molar shapes. Moreover, these shapes changed through the 16 years of the record, in agreement with expectations of drift for the molar, but more than expected by chance for the mandible. These results suggest that mice responded to the recent changes in food resources, possibly with a part of plastic variation for the mandible prone to bone remodelling. This pattern exemplifies the intricate interplay of evolution, ecology and plasticity that is a probable key of the success of such an invasive rodent facing pronounced shifts in food resources exploitation under a changing environment.
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Affiliation(s)
- S Renaud
- Laboratoire de Biométrie et Biologie Evolutive, UMR 5558, CNRS, Université de Lyon, Villeurbanne, France.
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55
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Gomes Rodrigues H, Solé F, Charles C, Tafforeau P, Vianey-Liaud M, Viriot L. Evolutionary and biological implications of dental mesial drift in rodents: the case of the Ctenodactylidae (Rodentia, Mammalia). PLoS One 2012. [PMID: 23185576 PMCID: PMC3503976 DOI: 10.1371/journal.pone.0050197] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Dental characters are importantly used for reconstructing the evolutionary history of mammals, because teeth represent the most abundant material available for the fossil species. However, the characteristics of dental renewal are presently poorly used, probably because dental formulae are frequently not properly established, whereas they could be of high interest for evolutionary and developmental issues. One of the oldest rodent families, the Ctenodactylidae, is intriguing in having longstanding disputed dental formulae. Here, we investigated 70 skulls among all extant ctenodactylid genera (Ctenodactylus, Felovia, Massoutiera and Pectinator) by using X-ray conventional and synchrotron microtomography in order to solve and discuss these dental issues. Our study clearly indicates that Massoutiera, Felovia and Ctenodactylus differ from Pectinator not only by a more derived dentition, but also by a more derived eruptive sequence. In addition to molars, their dentition only includes the fourth deciduous premolars, and no longer bears permanent premolars, conversely to Pectinator. Moreover, we found that these premolars are lost during adulthood, because of mesial drift of molars. Mesial drift is a striking mechanism involving migration of teeth allowed by both bone remodeling and dental resorption. This dental innovation is to date poorly known in rodents, since it is only the second report described. Interestingly, we noted that dental drift in rodents is always associated with high-crowned teeth favoring molar size enlargement. It can thus represent another adaptation to withstand high wear, inasmuch as these rodents inhabit desert environments where dust is abundant. A more accurate study of mesial drift in rodents would be very promising from evolutionary, biological and orthodontic points of view.
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Affiliation(s)
- Helder Gomes Rodrigues
- Team “Evo-Devo of Vertebrate Dentition”, Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242 Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
- * E-mail: (HGR); (LV)
| | - Floréal Solé
- Team “Evo-Devo of Vertebrate Dentition”, Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242 Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Cyril Charles
- Team “Evo-Devo of Vertebrate Dentition”, Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242 Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Paul Tafforeau
- European Synchrotron Radiation Facility, Grenoble, France
| | - Monique Vianey-Liaud
- Laboratoire de Paléontologie, Institut des Sciences de l’Évolution de Montpellier, Unité Mixte de Recherche 5554 Centre National de la Recherche Scientifique, Université Montpellier 2, Montpellier, France
| | - Laurent Viriot
- Team “Evo-Devo of Vertebrate Dentition”, Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242 Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
- * E-mail: (HGR); (LV)
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56
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Grieco TM, Rizk OT, Hlusko LJ. A MODULAR FRAMEWORK CHARACTERIZES MICRO- AND MACROEVOLUTION OF OLD WORLD MONKEY DENTITIONS. Evolution 2012; 67:241-59. [DOI: 10.1111/j.1558-5646.2012.01757.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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57
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Zahradnicek O, Horacek I, Tucker AS. Tooth development in a model reptile: functional and null generation teeth in the gecko Paroedura picta. J Anat 2012; 221:195-208. [PMID: 22780101 PMCID: PMC3458625 DOI: 10.1111/j.1469-7580.2012.01531.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2012] [Indexed: 11/29/2022] Open
Abstract
This paper describes tooth development in a basal squamate, Paroedura picta. Due to its reproductive strategy, mode of development and position within the reptiles, this gecko represents an excellent model organism for the study of reptile development. Here we document the dental pattern and development of non-functional (null generation) and functional generations of teeth during embryonic development. Tooth development is followed from initiation to cytodifferentiation and ankylosis, as the tooth germs develop from bud, through cap to bell stages. The fate of the single generation of non-functional (null generation) teeth is shown to be variable, with some teeth being expelled from the oral cavity, while others are incorporated into the functional bone and teeth, or are absorbed. Fate appears to depend on the initiation site within the oral cavity, with the first null generation teeth forming before formation of the dental lamina. We show evidence for a stratum intermedium layer in the enamel epithelium of functional teeth and show that the bicuspid shape of the teeth is created by asymmetrical deposition of enamel, and not by folding of the inner dental epithelium as observed in mammals.
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Affiliation(s)
- Oldrich Zahradnicek
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic.
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58
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Labonne G, Laffont R, Renvoise E, Jebrane A, Labruere C, Chateau‐Smith C, Navarro N, Montuire S. When less means more: evolutionary and developmental hypotheses in rodent molars. J Evol Biol 2012; 25:2102-2111. [DOI: 10.1111/j.1420-9101.2012.02587.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 07/04/2012] [Accepted: 07/04/2012] [Indexed: 11/28/2022]
Affiliation(s)
- G. Labonne
- Laboratoire Paléobiodiversité et Evolution de l'EPHE Université de Bourgogne Dijon France
- UMR CNRS 6282 Biogéosciences Université de Bourgogne Dijon France
| | - R. Laffont
- UMR CNRS 6282 Biogéosciences Université de Bourgogne Dijon France
| | - E. Renvoise
- Institute of Biotechnology University of Helsinki Helsinki Finland
| | - A. Jebrane
- Institut mathématique de Bourgogne UMR CNRS 5584 Dijon France
| | - C. Labruere
- Institut mathématique de Bourgogne UMR CNRS 5584 Dijon France
| | | | - N. Navarro
- Laboratoire Paléobiodiversité et Evolution de l'EPHE Université de Bourgogne Dijon France
- UMR CNRS 6282 Biogéosciences Université de Bourgogne Dijon France
| | - S. Montuire
- Laboratoire Paléobiodiversité et Evolution de l'EPHE Université de Bourgogne Dijon France
- UMR CNRS 6282 Biogéosciences Université de Bourgogne Dijon France
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59
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Häärä O, Harjunmaa E, Lindfors PH, Huh SH, Fliniaux I, Åberg T, Jernvall J, Ornitz DM, Mikkola ML, Thesleff I. Ectodysplasin regulates activator-inhibitor balance in murine tooth development through Fgf20 signaling. Development 2012; 139:3189-99. [PMID: 22833125 DOI: 10.1242/dev.079558] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Uncovering the origin and nature of phenotypic variation within species is the first step in understanding variation between species. Mouse models with altered activities of crucial signal pathways have highlighted many important genes and signal networks regulating the morphogenesis of complex structures, such as teeth. The detailed analyses of these models have indicated that the balanced actions of a few pathways regulating cell behavior modulate the shape and number of teeth. Currently, however, most mouse models studied have had gross alteration of morphology, whereas analyses of more subtle modification of morphology are required to link developmental studies to evolutionary change. Here, we have analyzed a signaling network involving ectodysplasin (Eda) and fibroblast growth factor 20 (Fgf20) that subtly affects tooth morphogenesis. We found that Fgf20 is a major downstream effector of Eda and affects Eda-regulated characteristics of tooth morphogenesis, including the number, size and shape of teeth. Fgf20 function is compensated for by other Fgfs, in particular Fgf9 and Fgf4, and is part of an Fgf signaling loop between epithelium and mesenchyme. We showed that removal of Fgf20 in an Eda gain-of-function mouse model results in an Eda loss-of-function phenotype in terms of reduced tooth complexity and third molar appearance. However, the extra anterior molar, a structure lost during rodent evolution 50 million years ago, was stabilized in these mice.
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Affiliation(s)
- Otso Häärä
- Developmental Biology Program, Institute of Biotechnology, University of Helsinki, POB 56, 00014 Helsinki, Finland
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60
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Jheon AH, Seidel K, Biehs B, Klein OD. From molecules to mastication: the development and evolution of teeth. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 2:165-82. [PMID: 24009032 DOI: 10.1002/wdev.63] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Teeth are unique to vertebrates and have played a central role in their evolution. The molecular pathways and morphogenetic processes involved in tooth development have been the focus of intense investigation over the past few decades, and the tooth is an important model system for many areas of research. Developmental biologists have exploited the clear distinction between the epithelium and the underlying mesenchyme during tooth development to elucidate reciprocal epithelial/mesenchymal interactions during organogenesis. The preservation of teeth in the fossil record makes these organs invaluable for the work of paleontologists, anthropologists, and evolutionary biologists. In addition, with the recent identification and characterization of dental stem cells, teeth have become of interest to the field of regenerative medicine. Here, we review the major research areas and studies in the development and evolution of teeth, including morphogenesis, genetics and signaling, evolution of tooth development, and dental stem cells.
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Affiliation(s)
- Andrew H Jheon
- Department of Orofacial Sciences and Program in Craniofacial and Mesenchymal Biology, University of California San Francisco, San Francisco, CA, USA
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61
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Rothová M, Peterková R, Tucker AS. Fate map of the dental mesenchyme: dynamic development of the dental papilla and follicle. Dev Biol 2012; 366:244-54. [PMID: 22542602 DOI: 10.1016/j.ydbio.2012.03.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 03/01/2012] [Accepted: 03/30/2012] [Indexed: 11/18/2022]
Abstract
At the bud stage of tooth development the neural crest derived mesenchyme condenses around the dental epithelium. As the tooth germ develops and proceeds to the cap stage, the epithelial cervical loops grow and appear to wrap around the condensed mesenchyme, enclosing the cells of the forming dental papilla. We have fate mapped the dental mesenchyme, using in vitro tissue culture combined with vital cell labelling and tissue grafting, and show that the dental mesenchyme is a much more dynamic population then previously suggested. At the bud stage the mesenchymal cells adjacent to the tip of the bud form both the dental papilla and dental follicle. At the early cap stage a small population of highly proliferative mesenchymal cells in close proximity to the inner dental epithelium and primary enamel knot provide the major contribution to the dental papilla. These cells are located between the cervical loops, within a region we have called the body of the enamel organ, and proliferate in concert with the epithelium to create the dental papilla. The condensed dental mesenchymal cells that are not located between the body of the enamel organ, and therefore are at a distance from the primary enamel knot, contribute to the dental follicle, and also the apical part of the papilla, where the roots will ultimately develop. Some cells in the presumptive dental papilla at the cap stage contribute to the follicle at the bell stage, indicating that the dental papilla and dental follicle are still not defined populations at this stage. These lineage-tracing experiments highlight the difficulty of targeting the papilla and presumptive odontoblasts at early stages of tooth development. We show that at the cap stage, cells destined to form the follicle are still competent to form dental papilla specific cell types, such as odontoblasts, and produce dentin, if placed in contact with the inner dental epithelium. Cell fate of the dental mesenchyme at this stage is therefore determined by the epithelium.
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Affiliation(s)
- Michaela Rothová
- Department of Craniofacial Development, King's College London, Floor 27 Guy's Tower, Guy's Hospital, London Bridge, SE1 9RT, London, UK.
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62
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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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63
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Charles C, Hovorakova M, Ahn Y, Lyons DB, Marangoni P, Churava S, Biehs B, Jheon A, Lesot H, Balooch G, Krumlauf R, Viriot L, Peterkova R, Klein OD. Regulation of tooth number by fine-tuning levels of receptor-tyrosine kinase signaling. Development 2011; 138:4063-73. [PMID: 21862563 DOI: 10.1242/dev.069195] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Much of our knowledge about mammalian evolution comes from examination of dental fossils, because the highly calcified enamel that covers teeth causes them to be among the best-preserved organs. As mammals entered new ecological niches, many changes in tooth number occurred, presumably as adaptations to new diets. For example, in contrast to humans, who have two incisors in each dental quadrant, rodents only have one incisor per quadrant. The rodent incisor, because of its unusual morphogenesis and remarkable stem cell-based continuous growth, presents a quandary for evolutionary biologists, as its origin in the fossil record is difficult to trace, and the genetic regulation of incisor number remains a largely open question. Here, we studied a series of mice carrying mutations in sprouty genes, the protein products of which are antagonists of receptor-tyrosine kinase signaling. In sprouty loss-of-function mutants, splitting of gene expression domains and reduced apoptosis was associated with subdivision of the incisor primordium and a multiplication of its stem cell-containing regions. Interestingly, changes in sprouty gene dosage led to a graded change in incisor number, with progressive decreases in sprouty dosage leading to increasing numbers of teeth. Moreover, the independent development of two incisors in mutants with large decreases in sprouty dosage mimicked the likely condition of rodent ancestors. Together, our findings indicate that altering genetic dosage of an antagonist can recapitulate ancestral dental characters, and that tooth number can be progressively regulated by changing levels of activity of a single signal transduction pathway.
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Affiliation(s)
- Cyril Charles
- Department of Orofacial Sciences and Program in Craniofacial and Mesenchymal Biology, University of California San Francisco, San Francisco, CA 94143, USA
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64
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Rodrigues HG, Charles C, Marivaux L, Vianey-Liaud M, Viriot L. Evolutionary and developmental dynamics of the dentition in Muroidea and Dipodoidea (Rodentia, Mammalia). Evol Dev 2011; 13:361-9. [DOI: 10.1111/j.1525-142x.2011.00491.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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65
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Li L, Yuan G, Liu C, Zhang L, Zhang Y, Chen Y, Chen Z. Exogenous fibroblast growth factor 8 rescues development of mouse diastemal vestigial tooth ex vivo. Dev Dyn 2011; 240:1344-53. [PMID: 21412937 PMCID: PMC3092827 DOI: 10.1002/dvdy.22596] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/27/2011] [Indexed: 12/21/2022] Open
Abstract
Regression of vestigial tooth buds results in the formation of the toothless diastema, a unique feature of the mouse dentition. Revitalization of the diastemal vestigial tooth bud provides an excellent model for studying tooth regeneration and replacement. It has been previously shown that suppression of fibroblast growth factor (FGF) signaling in the diastema results in vestigial tooth bud regression. In this study, we report that application of exogenous FGF8 to the mouse embryonic diastemal region rescues diastemal tooth development. However, this rescue of diastemal tooth development occurs only in an isolated diastemal regions and not in the mandibular quadrant, which includes the incisor and molar germs. FGF8 promotes cell proliferation and inhibits apoptosis in diastemal tooth epithelium, and revitalizes the tooth developmental program, as evidenced by the expression of genes critical for normal tooth development. Our results also support the idea that the adjacent tooth germs contribute to the suppression of diastemal vestigial tooth buds by means of multiple signals.
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Affiliation(s)
- Lu Li
- Hubei-MOST KLOS and KLOBM School and Hospital of Stomatology Wuhan University Wuhan, Hubei Province, P.R. China
- Department of Cell and Molecular Biology Tulane University New Orleans, LA 70118, USA
| | - Guohua Yuan
- Hubei-MOST KLOS and KLOBM School and Hospital of Stomatology Wuhan University Wuhan, Hubei Province, P.R. China
| | - Chao Liu
- Department of Cell and Molecular Biology Tulane University New Orleans, LA 70118, USA
| | - Lu Zhang
- Hubei-MOST KLOS and KLOBM School and Hospital of Stomatology Wuhan University Wuhan, Hubei Province, P.R. China
| | - Yanding Zhang
- Fujian Key Laboratory of Developmental and Neuro Biology College of Life Sciences Fujian Normal University Fuzhou, Fujian Province, P.R. China
| | - YiPing Chen
- Department of Cell and Molecular Biology Tulane University New Orleans, LA 70118, USA
- Fujian Key Laboratory of Developmental and Neuro Biology College of Life Sciences Fujian Normal University Fuzhou, Fujian Province, P.R. China
| | - Zhi Chen
- Hubei-MOST KLOS and KLOBM School and Hospital of Stomatology Wuhan University Wuhan, Hubei Province, P.R. China
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66
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Renaud S, Pantalacci S, Auffray JC. Differential evolvability along lines of least resistance of upper and lower molars in island house mice. PLoS One 2011; 6:e18951. [PMID: 21589657 PMCID: PMC3092747 DOI: 10.1371/journal.pone.0018951] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 03/15/2011] [Indexed: 11/30/2022] Open
Abstract
Variation within a population is a key feature in evolution, because it can increase or impede response to selection, depending on whether or not the intrapopulational variance is correlated to the change under selection. Hence, main directions of genetic variance have been proposed to constitute “lines of least resistance to evolution” along which evolution would be facilitated. Yet, the screening of selection occurs at the phenotypic level, and the phenotypic variance is not only the product of the underlying genetic variance, but also of developmental processes. It is thus a key issue for interpreting short and long term evolutionary patterns to identify whether main directions of phenotypic variance indeed constitute direction of facilitated evolution, and whether this is favored by developmental processes preferably generating certain phenotypes. We tackled these questions by a morphometric quantification of the directions of variance, compared to the direction of evolution of the first upper and lower molars of wild continental and insular house mice. The main phenotypic variance indeed appeared as channeling evolution between populations. The upper molar emerged as highly evolvable, because a strong allometric component contributed to its variance. This allometric relationship drove a repeated but independent evolution of a peculiar upper molar shape whenever size increased. This repeated evolution, together with knowledge about the molar development, suggest that the main direction of phenotypic variance correspond here to a “line of least developmental resistance” along which evolution between population is channeled.
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Affiliation(s)
- Sabrina Renaud
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, Villeurbanne, France.
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67
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Wang XP, Fan J. Molecular genetics of supernumerary tooth formation. Genesis 2011; 49:261-77. [PMID: 21309064 DOI: 10.1002/dvg.20715] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 01/02/2011] [Accepted: 01/06/2011] [Indexed: 01/07/2023]
Abstract
Despite advances in the knowledge of tooth morphogenesis and differentiation, relatively little is known about the aetiology and molecular mechanisms underlying supernumerary tooth formation. A small number of supernumerary teeth may be a common developmental dental anomaly, while multiple supernumerary teeth usually have a genetic component and they are sometimes thought to represent a partial third dentition in humans. Mice, which are commonly used for studying tooth development, only exhibit one dentition, with very few mouse models exhibiting supernumerary teeth similar to those in humans. Inactivation of Apc or forced activation of Wnt/β(catenin signalling results in multiple supernumerary tooth formation in both humans and in mice, but the key genes in these pathways are not very clear. Analysis of other model systems with continuous tooth replacement or secondary tooth formation, such as fish, snake, lizard, and ferret, is providing insights into the molecular and cellular mechanisms underlying succesional tooth development, and will assist in the studies on supernumerary tooth formation in humans. This information, together with the advances in stem cell biology and tissue engineering, will pave ways for the tooth regeneration and tooth bioengineering.
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Affiliation(s)
- Xiu-Ping Wang
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard University, Boston, Massachusetts 02115, USA.
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68
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Hovorakova M, Prochazka J, Lesot H, Smrckova L, Churava S, Boran T, Kozmik Z, Klein O, Peterkova R, Peterka M. Shh expression in a rudimentary tooth offers new insights into development of the mouse incisor. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2011; 316:347-58. [PMID: 21455944 DOI: 10.1002/jez.b.21408] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 02/08/2011] [Accepted: 02/16/2011] [Indexed: 01/26/2023]
Abstract
For teeth as for any organ, knowledge of normal development is essential for the proper interpretation of developmental anomalies in mutant mice. It is generally accepted that tooth formation is initiated with a single signaling center that, in the incisor region, is exclusively related to the development of the functional adult incisor. Here, using a unique combination of computer-aided three-dimensional reconstructions and whole mount in situ hybridization of mandibles from finely staged wild-type mouse embryos, we demonstrate that several Sonic hedgehog (Shh) expression domains sequentially appear in the lower incisor region during early development. In contrast to the single Shh expression domain that is widely assumed to be present in each lower incisor area at ED12.5-13.5, we identified two spatially distinct regions of Shh expression that appear in an anterior-posterior sequence during this period. The initial anterior, more superficially located Shh expression region represented the rudimentary (so-called deciduous) incisor, whereas only the later posterior deeper situated region corresponded to the prospective functional incisor. In the more advanced embryos, only this posterior Shh expression in the incisor bud was detectable as a precursor of the enamel knot. This study offers a new interpretation of published molecular data on the mouse incisor from initiation through ED13.5. We suggest that, as with Shh expression, other molecular data that have been ascribed to the progressive development of the mouse functional incisor at early stages, in fact, correspond to a rudimentary incisor whose development is aborted.
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Affiliation(s)
- Maria Hovorakova
- Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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69
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Porntaveetus T, Otsuka-Tanaka Y, Basson MA, Moon AM, Sharpe PT, Ohazama A. Expression of fibroblast growth factors (Fgfs) in murine tooth development. J Anat 2011; 218:534-43. [PMID: 21332717 DOI: 10.1111/j.1469-7580.2011.01352.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Fgf signalling is known to play critical roles in tooth development. Twenty-two Fgf ligands have been identified in mammals, but expression of only 10 in molars and three in the incisor loop stem cell region have been documented in murine tooth development. Our understanding of Fgf signalling in tooth development thus remains incomplete and we therefore carried out comparative in situ hybridisation analysis of unexamined Fgf ligands (eight in molars and 15 in cervical loops of incisors; Fgf11-Fgf14 were excluded from this analysis because they are not secreted and do not activate Fgf receptors) during tooth development. To identify where Fgf signalling is activated, we also examined the expression of Etv4 and Etv5, considered to be transcriptional targets of the Fgf signalling pathway. In molar tooth development, the expression of Fgf15 and Fgf20 was restricted to the primary enamel knots, whereas Etv4 and Etv5 were expressed in cells surrounding the primary enamel knots. Fgf20 expression was observed in the secondary enamel knots, whereas Fgf15 showed localised expression in the adjacent mesenchyme. Fgf16, Etv4 and Etv5 were strongly expressed in the ameloblasts of molars. In the incisor cervical loop stem cell region, Fgf17, Fgf18, Etv4 and Etv5 showed a restricted expression pattern. These molecules thus show dynamic temporo-spatial expression in murine tooth development. We also analysed teeth in Fgf15(-/-) and Fgf15(-/-) ;Fgf8(+/-) mutant mice. Neither mutant showed significant abnormalities in tooth development, indicating likely functional redundancy.
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Affiliation(s)
- Thantrira Porntaveetus
- Department of Craniofacial Development, Dental Institute, King's College London, Guy's Hospital, London, UK
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