Changes in the protein components of rat incisor enamel during tooth development

Robinson, C.; Briggs, H.D.; Kirkham, J; Atkinson, Peter J.

doi:10.1016/0003-9969(83)90053-5

Cited by 42 publications

(35 citation statements)

References 20 publications

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“…However, in contrast to amelogenins-which are lost during enamel secretion (ROBINSON et al, 1983;KIRKHAM, 1984, 1985)-enamelins persist in enamel (BELCOURT, 1982); they either are not resorbed into secretory ameloblasts, or it is believed that the immunolabeling in multivesicular bodies are related to the modification of the secretory product or degradation of enamelins being formed in the cell.…”

Section: Degradation and Resorption Of Enamel Proteinsmentioning

confidence: 99%

“…Amelogenins are lost during enamel secretion, and a tuft protein characterized by high serine and glycine contents (RoBINSoN et al, 1983;KIRKHAM, 1984, 1985), or enamelins (BELCOURT, 1982), is retained in the mature enamel. NANCI et al (1987) showed that the immunoreactivity for amelogenins in lysosomes including multivesicular bodies was stronger at the secretory stage than at the maturation stage.…”

Section: The Maturation Stage Of Ameloblastsmentioning

confidence: 99%

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Immunocytochemical demonstration of amelogenins and enamelins secreted by ameloblasts during the secretory and maturation stages.

Inage

Shimokawa

Teranishi

et al. 1989

Archives of Histology and Cytology

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Section: Degradation and Resorption Of Enamel Proteinsmentioning

confidence: 99%

Section: The Maturation Stage Of Ameloblastsmentioning

confidence: 99%

Immunocytochemical demonstration of amelogenins and enamelins secreted by ameloblasts during the secretory and maturation stages.

Inage

Shimokawa

Teranishi

et al. 1989

Archives of Histology and Cytology

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“…The organic matrix of enamel is believed to contain two main subfamilies of proteins termed amelogenins and enamelins (reviewed in Eastoe, 1979; Termine et al, 1980; Robinson et al, 1983;Shimizu and Fukae, 1983;Fincham and Belcourt, 1985; Robinson and Kirkham, 1985). Amelogenins are found in highest concentrations within newly formed and partially mineralized "young" enamel.…”

Section: Introductionmentioning

confidence: 98%

“…Enamelins comprise the major protein associated with the mineral in fully "mature" enamel (references above). Current biochemical evidence suggests that small amounts of enamelins are present along with (Termine et al, 1980;Robinson et al, 1983;Shimokawa et al, 1984;Zeichner-David et al, 1985). Hence, enamel maturation is viewed as a process which results in the breakdown and selective loss of amelogenins with the preferential retention of the enamelins (reviewed in Robinson and Kirkham, 1985).…”

mentioning

confidence: 94%

Immunocytochemical and radioautographic evidence for secretion and intracellular degradation of enamel proteins by ameloblasts during the maturation stage of amelogenesis in rat incisors

Nanci¹,

Slavkin²,

Smith³

1987

Anat. Rec.

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In the continuously erupting rat incisor the ameloblasts progress through distinct stages associated with the secretion and maturation of enamel. We have examined the possibility that the so-called "postsecretory" ameloblasts of the maturation stage of amelogenesis remain biosynthetically active and are engaged in the synthesis, secretion, and degradation of enamel gene products. The ultrastructural distribution of antigenic sites for enamel proteins was studied within enamel organ cells during the early maturation stage of amelogenesis in rat incisors by using the protein A-gold immunocytochemical technique and rabbit polyclonal antibodies developed against mouse amelogenins. All regions of amelogenesis from late secretion through the first complete modulation from ruffle-ended to smooth-ended ameloblasts were examined. Specific immunolabelling was found within the rough endoplasmic reticulum, Golgi saccules, secretory granules, and lysosomes of ameloblasts throughout these regions. The heaviest intracellular immunolabelling was found within secretory granules and lysosomes (multivesicular type). Quantitative analyses showed that the Golgi saccules and the multivesicular lysosomes of modulating ameloblasts were generally less immunoreactive compared to similar organelles in ameloblasts secreting the inner enamel layer. Radioautographic studies confirmed that ameloblasts of the maturation stage incorporated 3H-leucine and 3H-methionine and secreted labelled proteins into the enamel layer. Grain counts indicated that ameloblasts from the first ruffle-ended band incorporated about two-fold less 3H-methionine and secreted about tenfold less labelled proteins into the enamel compared to ameloblasts secreting the inner enamel layer. The results of this study confirm that ameloblasts do not terminate biosynthesis and secretion of enamel proteins once the final layer has been deposited on the surface of the developing enamel. They continue to form and release new proteins during the maturation stage which intermix with older proteins laid down initially during the secretory stage of amelogenesis. Secretory activity for enamel proteins has been detected in ameloblasts up to at least the second ruffle-ended phase of maturation, at which point the enamel matrix is partially soluble in EDTA.

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“…Amelogenin is the predominant component and comprises ϳ90% of total enamel matrix protein (10). Interestingly, the full-length enamel proteins are found only at the mineralizing front, suggesting that they participate in crystal elongation (11)(12)(13)(14)(15)(16)(17)(18)(19). In contrast, the protein cleavage products are found throughout the enamel layer, suggesting that they prevent crystallite growth in width and thickness (16).…”

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confidence: 99%

Enamelysin (Matrix Metalloproteinase 20)-deficient Mice Display an Amelogenesis Imperfecta Phenotype

Caterina¹,

Skobe²,

Shi³

et al. 2002

Journal of Biological Chemistry

237

243

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Enamelysin is a tooth-specific matrix metalloproteinase that is expressed during the early through middle stages of enamel development. The enamel matrix proteins amelogenin, ameloblastin, and enamelin are also expressed during this same approximate developmental time period, suggesting that enamelysin may play a role in their hydrolysis. In support of this interpretation, recombinant enamelysin was previously demonstrated to cleave recombinant amelogenin at virtually all of the precise sites known to occur in vivo. Thus, enamelysin is likely an important amelogenin-processing enzyme. To characterize the in vivo biological role of enamelysin during tooth development, we generated an enamelysindeficient mouse by gene targeting. Although mice heterozygous for the mutation have no apparent phenotype, the enamelysin null mouse has a severe and profound tooth phenotype. Specifically, the null mouse does not process amelogenin properly, possesses an altered enamel matrix and rod pattern, has hypoplastic enamel that delaminates from the dentin, and has a deteriorating enamel organ morphology as development progresses. Our findings demonstrate that enamelysin activity is essential for proper enamel development.Dental enamel covers the crown of the tooth and is unique among mineralized tissues because of its high mineral content, large crystals, and organized prism pattern. Other mineralized tissues such as bone, dentin, and cementum are composed of ϳ20% organic material. In contrast, mature enamel has less than 1% organic matter by weight (1, 2). Moreover, enamel crystallites possess a volume that is 100 times greater than the volume of crystallites found in other mineralizing tissues. These enamel crystallites form enamel rods that, in turn, form a unique interlacing (decussating) prism pattern. As a result, dental enamel is the hardest substance in the body. Its hardness is intermediate between that of iron and carbon steel, yet it also has a high elasticity (3).Although mature enamel is a very hard protein-free tissue, it does not start this way. Enamel development (amelogenesis) consists of several stages that include the secretory, transition, and maturation stages. During the secretory stage, enamel crystallites elongate into long thin ribbons that are only a few apatitic unit cells in thickness (about 10 nm) with a width of ϳ30 nm (4, 5). The ribbons are evenly spaced, are oriented parallel to each other, and grow in length but very little in width and thickness. Ultimately, enamel crystal length determines the final thickness of the enamel layer as a whole (for review, see Ref. 6). It is during the secretory stage that the columnar-shaped ameloblast cells, located adjacent to the forming enamel, secrete specialized enamel proteins into the enamel matrix. These proteins include amelogenin (7), ameloblastin (8), and enamelin (9). Amelogenin is the predominant component and comprises ϳ90% of total enamel matrix protein (10). Interestingly, the full-length enamel proteins are found only at the mineralizing front, su...

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Changes in the protein components of rat incisor enamel during tooth development

Cited by 42 publications

References 20 publications

Immunocytochemical demonstration of amelogenins and enamelins secreted by ameloblasts during the secretory and maturation stages.

Immunocytochemical demonstration of amelogenins and enamelins secreted by ameloblasts during the secretory and maturation stages.

Immunocytochemical and radioautographic evidence for secretion and intracellular degradation of enamel proteins by ameloblasts during the maturation stage of amelogenesis in rat incisors

Enamelysin (Matrix Metalloproteinase 20)-deficient Mice Display an Amelogenesis Imperfecta Phenotype

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