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1.
Lu Y Ye L Yu S Zhang S Xie Y McKee MD Li YC Kong J Eick JD Dallas SL Feng JQ 《Developmental biology》2007,303(1):191-201
Dentin matrix protein 1 (DMP1) is expressed in both pulp and odontoblast cells and deletion of the Dmp1 gene leads to defects in odontogenesis and mineralization. The goals of this study were to examine how DMP1 controls dentin mineralization and odontogenesis in vivo. Fluorochrome labeling of dentin in Dmp1-null mice showed a diffuse labeling pattern with a 3-fold reduction in dentin appositional rate compared to controls. Deletion of DMP1 was also associated with abnormalities in the dentinal tubule system and delayed formation of the third molar. Unlike the mineralization defect in Vitamin D receptor-null mice, the mineralization defect in Dmp1-null mice was not rescued by a high calcium and phosphate diet, suggesting a different effect of DMP1 on mineralization. Re-expression of Dmp1 in early and late odontoblasts under control of the Col1a1 promoter rescued the defects in mineralization as well as the defects in the dentinal tubules and third molar development. In contrast, re-expression of Dmp1 in mature odontoblasts, using the Dspp promoter, produced only a partial rescue of the mineralization defects. These data suggest that DMP1 is a key regulator of odontoblast differentiation, formation of the dentin tubular system and mineralization and its expression is required in both early and late odontoblasts for normal odontogenesis to proceed. 相似文献
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Yozo Gotoh Shigeru Saito Atsushige Sato 《Biochimica et Biophysica Acta (BBA)/General Subjects》1979,587(2):253-262
Studies were performed to determine whether cultured odontogenic cells from rabbit tooth germ (RP cell) could synthesize dentine-like collagen. When cells were cultured with [14C]proline, 33% of the total incorporated proteins present were collagenous. Cultured RP cells were labelled with [14C]proline in the presence of β-aminopropionitrile. The resulting fractions, on analysis by CM-cellulose chromatography, contained three radioactive protein peaks, α1(I), [α1(III)]3, α2. From the radioactive measurements, RP cells synthesized a significant amount of type III collagen, comparable to type I collagen.DEAE-cellulose chromatography was used to separate collagen molecules from collagen precursors. The results showed that 60% of total collagen precursor was type III precursor and the remainder was type I precursor.CM-cellulose chromatography of CNBr peptides of collagen from culture medium and cell extract revealed the presence of type I and type III collagen. Thus, the RP cell, which is a diploid cell, is unique in the predominance of type III collagen in culture, differing thereby from the character of collagen in vivo. 相似文献
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Gregory R. Handrigan 《Developmental biology》2010,337(1):171-258
Here we study the role of Shh signaling in tooth morphogenesis and successional tooth initiation in snakes and lizards (Squamata). By characterizing the expression of Shh pathway receptor Ptc1 in the developing dentitions of three species (Eublepharis macularius, Python regius, and Pogona vitticeps) and by performing gain- and loss-of-function experiments, we demonstrate that Shh signaling is active in the squamate tooth bud and is required for its normal morphogenesis. Shh apparently mediates tooth morphogenesis by separate paracrine- and autocrine-mediated functions. According to this model, paracrine Shh signaling induces cell proliferation in the cervical loop, outer enamel epithelium, and dental papilla. Autocrine signaling within the stellate reticulum instead appears to regulate cell survival. By treating squamate dental explants with Hh antagonist cyclopamine, we induced tooth phenotypes that closely resemble the morphological and differentiation defects of vestigial, first-generation teeth in the bearded dragon P. vitticeps. Our finding that these vestigial teeth are deficient in epithelial Shh signaling further corroborates that Shh is needed for the normal development of teeth in snakes and lizards. Finally, in this study, we definitively refute a role for Shh signaling in successional dental lamina formation and conclude that other pathways regulate tooth replacement in squamates. 相似文献
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In addition to being an advantageous model to investigate general molecular mechanisms of organ formation, the tooth is a distinct target organ for peripheral nerve innervation. These nerves are required for the function and protection of the teeth and, as shown in fish, also for their regeneration. This review focuses on recent findings of the local tissue interactions and molecular signaling mechanisms that regulate the early nerve arrival and patterning of mouse mandibular molar tooth sensory innervation. 相似文献
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Tooth eruption consists of the movement of teeth from the bony crypt in which they initiate their development to the occlusal
plane in the oral cavity. Interactions between the tooth germ and its surrounding alveolar bone occur in order to offer spatial
conditions for its development and eruption. This involves bone remodeling during which resoption is a key event. Bisphosphonates
are a group of drugs that interfere with the resorption of mineralized tissues. With the purpose of investigating the effects
of sodium alendronate (a potent bisphosphonate inhibitor of osteoclast activity) on alveolar bone during tooth development
and eruption, we gave newborn rats daily doses of this drug for 4, 14, and 30 days. Samples of the maxillary alveolar process
containing the tooth germs were processed for light, transmission, and scanning electron microscopy and were also submitted
to tartrate-resistant acid phosphatase histochemistry and high-resolution colloidal-gold immunolabeling for osteopontin. Inhibition
of osteoclast activity by sodium alendronate caused the absence of tooth eruption. The lack of alveolar bone remodeling resulted
in primary bone with the presence of latent osteoclasts and abundant osteopontin at the interfibrillar regions. The developing
bone trabeculae invaded the dental follicle and reached the molar tooth germs, provoking deformities in enamel surfaces. No
root formation was observed. These findings suggested that alendronate effectively inhibited tooth eruption by interfering
with the activation of osteoclasts, which remained in a latent stage.
This work was supported by grants from Fapesp (04/05831-9 and 06/60094-5) and CNPq (Brazil). 相似文献
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As shown in 62 pairs of dental opponents from 32 grossly normal human fetuses in the 75-378 mm crown-rump range, mandibular precedence is the rule for 11, 12, C and M1, a trend in agreement with mandibular precedence for deciduous teeth through dm1 and in the gingival emergence of the same permanent teeth during postnatal development. 相似文献
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Stem cells and tooth tissue engineering 总被引:5,自引:0,他引:5
The notion that teeth contain stem cells is based on the well-known repairing ability of dentin after injury. Dental stem
cells have been isolated according to their anatomical locations, colony-forming ability, expression of stem cell markers,
and regeneration of pulp/dentin structures in vivo. These dental-derived stem cells are currently under increasing investigation
as sources for tooth regeneration and repair. Further attempts with bone marrow mesenchymal stem cells and embryonic stem
cells have demonstrated the possibility of creating teeth from non-dental stem cells by imitating embryonic development mechanisms.
Although, as in tissue engineering of other organs, many challenges remain, stem-cell-based tissue engineering of teeth could
be a choice for the replacement of missing teeth in the future. 相似文献
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