Inhibition of tooth germ differentiation in vitro by diazo-oxo-norleucine (DON)

Development ◽  
1979 ◽  
Vol 50 (1) ◽  
pp. 99-109
Author(s):  
Kirsti Hurmerinta ◽  
Irma Thesleff ◽  
Lauri Saxén
Keyword(s):  
Close Association ◽  
Tooth Germ ◽  
Mesenchymal Cell ◽  
Mouse Embryos ◽  
Control Medium ◽  
Glycoprotein Synthesis ◽  
Odontoblast Differentiation ◽  
Cervical Cells ◽  
Tooth Germs

Molar tooth germs from mouse embryos were studied in a Trowell-type organ culture. After 5 days of culture the odontoblasts had secreted predentine and the ameloblasts had differentiated. When cultured in the presence of 10–50 μm diazo-oxo-norleucine (DON), which is a glutamine analogue, the differentiation of odontoblasts was inhibited, but the teeth looked otherwise healthy. When DON was added after 2 days of culture in control medium (at this tims the odontoblasts in the cuspal area were already differentiated), it did not inhibit predentine secretion, ameloblast differentiation, nor enamel secretion. However, this was seen only in the cuspal area and the boundary to the undifferentiated, more cervical cells was distinct. The results support the concept that the mechanism of the differentiation of odontoblasts is different from that of the ameloblasts. We have shown earlier that a close association between the basement msmbrane and the mesenchymal cells is required for odontoblast differentiation. Because DON inteiferes with glycosaminoglycan and glycoprotein synthesis we suggest that DON inhibits odontoblast differentiation by affecting the mesenchymal cell surface and/or the basement membrane.

Epithelial and mesenchymal cell interactions with extracellular matrix material in vitro

Development ◽  
1969 ◽  
Vol 22 (3) ◽  
pp. 395-405
Author(s):  
H. C. Slavkin ◽  
P. Bringas ◽  
J. Cameron ◽  
R. LeBaron ◽  
L. A. Bavetta
Keyword(s):  
Matrix Material ◽  
Chorioallantoic Membrane ◽  
Tooth Germ ◽  
Mesenchymal Cell ◽  
Basic Rule ◽  
Millipore Filter ◽  
Chick Chorioallantoic Membrane ◽  
Mammalian Embryos ◽  
Tooth Germs

Epidermal organogenesis (thyroid gland, salivary gland, feather, hair, skin, thymus gland, tooth, etc.) generally follows a basic rule; epithelium exhibits well-documented interdependence with adjacent mesenchyme for a specific path of development (Grobstein, 1967, for review). Koch (1967) demonstrated in rodent embryos that isolates of incisor epithelial and mesenchymal tissue, separated by a millipore filter, continued to develop. When homotypic tissues were placed in juxtaposition to the filter, no evidence of continued differentiation was observed. Isolated cervical loop tissues of tooth germs from mammalian embryos have been shown to develop into an entire tooth in vitro (Slavkin & Bavetta, 1968 a; Kollar & Baird, 1969). Our laboratory recently reported that isolated tissue preparations (Slavkin & Bavetta, 1968 a) or cell suspensions (Slavkin, Beierle & Bavetta, 1968) of epithelial and mesenchymal cells from the embryonic cervical loop, in recombination on the chick chorioallantoic membrane (CAM), reconstituted and developed into a tooth germ.

Tunicamycin inhibits mouse tooth morphogenesis and odontoblast differentiation in vitro

Development ◽  
1980 ◽  
Vol 58 (1) ◽  
pp. 195-208
Author(s):  
Irma Thesleff ◽  
Robert M. Pratt
Keyword(s):  
Basement Membrane ◽  
Tooth Germ ◽  
Mesenchymal Cells ◽  
Protein Glycosylation ◽  
Molar Tooth ◽  
Odontoblast Differentiation ◽  
Matrix Interaction ◽  
Cell Matrix ◽  
Dose Dependent

Tunicamycin (TM), an antibiotic that selectively inhibits dolichol-mediated protein glycosylation, inhibited morphogenesis and differentiation of odontoblasts in the molar tooth germ in vitro. These effects of TM are reversible and dose-dependent, and in advanced teeth the effect of TM was not complete unless the basement membrane was removed prior to culture. TM did not prevent secretion of predentin or enamel when added to the cultures after initiation of predentin secretion. TM dramatically inhibited protein glycosylation and the accumulation of labeled proteoglycans and glycoproteins in the basement membrane. Our previous studies indicated that odontoblast differentiation is triggered by an interaction between the basement membrane and mesenchymal cells. We suggest that TM inhibits odontoblast differentiation by causing alterations in the basement membrane which prevent the necessary cell-matrix interaction required for odontoblast differentiation.

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.

A Characterization of Amelogenin Messenger RNA in the Bovine Tooth Germ

1987 ◽  
Vol 1 (2) ◽  
pp. 289-292 ◽  
Author(s):  
M.F. Young ◽  
H.S. Shimokawa ◽  
M.E. Sobel ◽  
J.D. Termine
Keyword(s):  
Gel Electrophoresis ◽  
Messenger Rna ◽  
Matrix Protein ◽  
Tooth Germ ◽  
Northern Analysis ◽  
Incisor Tooth ◽  
Major Species ◽  
Tooth Germs

In order to study the nature of amelogenin mRNA, we isolated ameloblast-rich tissue from the unerupted permanent incisor tooth germs of 18-month-old steers and subjected it to guanidine HC1 solubilization for extraction of mRNA. When poly A+ ameloblast RNA was incubated with radioactive deoxynucleotides and reverse transcriptase, four major transcripts were detected with sizes of 1.9, 1.4, 0.7, and 0.4 kb in length. One of the transcripts (0.7 kb) corresponded precisely in length to that predicted from the size of the major in vitro translated amelogenin proteins (27,000 daltons). To determine whether the transcripts did indeed encode amelogenin mRNA, we constructed a λgt11 cDNA library and isolated several amelogenin cDNA's by screening with amelogenin antibody. Four clones were amplified and insert sizes determined by acrylamide gel electrophoresis. Two of the clones had insert sizes of ~ 0.7 kb (λAm 16, XAm 7), and two had insert sizes of ~ 0.4 kb (λAm 11, λAm 4). When the amelogenin cDNA was radiolabeled and used for northern analysis, two species of amelogenin message (0.75 and 0.45 kb) were evident, both of which showed extensive hybridization to λAm 16 (large) and λAm 11 (small) cDNA. These data indicate that: (1) Amelogenin mRNA is heterogeneous in the bovine tooth germ, having two major species 800 and 400 bases long; and (2) the major species of amelogenin share extensive sequence homology. Based on these data, we suggest that at least part of the heterogeneity of amelogenin matrix protein may arise from the production of heterogeneous amelogenin mRNA's that share some common nucleotide sequences.

scholarly journals Microstructured Hyaluronic Acid Hydrogel for Tooth Germ Bioengineering

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 123
Author(s):  
Sol Park ◽  
Naomi W. Y. Huang ◽  
Cheryl X. Y. Wong ◽  
Jing Pan ◽  
Lamyaa Albakr ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Psychological Health ◽  
Soft Lithography ◽  
Tooth Germ ◽  
Human Tooth ◽  
Hydrogel Scaffolds ◽  
Immunological Rejection ◽  
Tooth Germs

Tooth loss has been found to adversely affect not just masticatory and speech functions, but also psychological health and quality of life. Currently, teeth replacement options include dentures, bridges, and implants. However, these artificial replacement options remain inferior to biological replacements due to their reduced efficiency, the need for replacements, and the risk of immunological rejection. To this end, there has been a heightened interest in the bioengineering of teeth in recent years. While there have been reports of successfully regenerated teeth, controlling the size and shape of bioengineered teeth remains a challenge. In this study, methacrylated hyaluronic acid (MeHA) was synthesized and microstructured in a hydrogel microwell array using soft lithography. The resulting MeHA hydrogel microwell scaffold resembles the shape of a naturally developing human tooth germ. To facilitate the epithelial–mesenchymal interactions, human adult low calcium high temperature (HaCaT) cells were seeded on the surface of the hydrogels and dental pulp stem cells (DPSCs) were encapsulated inside the hydrogels. It was found that hydrogel scaffolds were able to preserve the viability of both types of cells and they appeared to favor signaling between epithelial and mesenchymal cells, which is necessary in the promotion of cell proliferation. As such, the hydrogel scaffolds offer a promising system for the bioengineering of human tooth germs in vitro.

Epigenetic Signals during Odontoblast Differentiation

2001 ◽  
Vol 15 (1) ◽  
pp. 8-13 ◽  
Author(s):  
H. Lesot ◽  
S. Lisi ◽  
R. Peterkova ◽  
M. Peterka ◽  
V. Mitolo ◽  
...  
Keyword(s):  
Functional Differentiation ◽  
Specific Pattern ◽  
Odontoblast Differentiation ◽  
Propagation Analysis ◽  
Matrix Interactions ◽  
Fibronectin Binding Protein ◽  
Tooth Germs ◽  
Extracellular Matrix Interactions

Odontoblast terminal differentiation occurs according to a tooth-specific pattern and implies both temporo-spatially regulated epigenetic signaling and the expression of specific competence. Differentiation of odontoblasts (withdrawal from the cell cycle, cytological polarization, and secretion of predentin/dentin) is controlled by the inner dental epithelium, and the basement membrane (BM) plays a major role both as a substrate and as a reservoir of paracrine molecules. Cytological differentiation implies changes in the organization of the cytoskeleton and is controlled by cytoskeleton-plasma membrane-extracellular matrix interactions. Fibronectin is re-distributed during odontoblast polarization and interacts with cell-surface molecules. A nonintegrin 165-kDa fibronectin-binding protein, transiently expressed by odontoblasts, is involved in microfilament reorganization. Growth factors (TGFβ1,2,3/BMP2,4, and 6), expressed in tooth germs, signal differentiation. Systemically derived molecules (IGF1) may also intervene. IGF1 stimulates cytological but not functional differentiation of odontoblasts: The two events can thus be separated. Immobilized TGFβ1 (combined with heparin) induced odontoblast differentiation. Only immobilized TGFβ1 and 3 or a combination of FGF1 and TGFβ1 stimulated the differentiation of functional odontoblasts over extended areas and allowed for maintenance of gradients of differentiation. Presentation of active molecules in vitro appeared to be of major importance; the BM should fulfill this role in vivo by immobilizing and spatially presenting TGF(3s. Attempts are being made to investigate the mechanisms which spatially control the initiation of odontoblast differentiation and those which regulate its propagation. Analysis of molar development suggested that odontoblast differentiation and crown morphogenesis are interdependent, although the possibility of co-regulation requires further investigation.

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.

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.

Diabetes and Heart Failure: Is it Hyperglycemia or Hyperinsulinemia?

2020 ◽  
Vol 18 (2) ◽  
pp. 148-157 ◽  
Author(s):  
Triantafyllos Didangelos ◽  
Konstantinos Kantartzis
Keyword(s):  
Heart Failure ◽  
Insulin Treatment ◽  
Close Association ◽  
Adverse Outcomes ◽  
Negative Effects ◽  
Beneficial Effects ◽  
Appropriate Treatment ◽  
Increased Risk ◽  
Treatment Of Diabetes

The cardiac effects of exogenously administered insulin for the treatment of diabetes (DM) have recently attracted much attention. In particular, it has been questioned whether insulin is the appropriate treatment for patients with type 2 diabetes mellitus and heart failure. While several old and some new studies suggested that insulin treatment has beneficial effects on the heart, recent observational studies indicate associations of insulin treatment with an increased risk of developing or worsening of pre-existing heart failure and higher mortality rates. However, there is actually little evidence that the associations of insulin administration with any adverse outcomes are causal. On the other hand, insulin clearly causes weight gain and may also cause serious episodes of hypoglycemia. Moreover, excess of insulin (hyperinsulinemia), as often seen with the use of injected insulin, seems to predispose to inflammation, hypertension, dyslipidemia, atherosclerosis, heart failure, and arrhythmias. Nevertheless, it should be stressed that most of the data concerning the effects of insulin on cardiac function derive from in vitro studies with isolated animal hearts. Therefore, the relevance of the findings of such studies for humans should be considered with caution. In the present review, we summarize the existing data about the potential positive and negative effects of insulin on the heart and attempt to answer the question whether any adverse effects of insulin or the consequences of hyperglycemia are more important and may provide a better explanation of the close association of DM with heart failure.

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