Amelin: An enamel-related protein, transcribed in the cells of epithelial root sheath

Fong, Cheng Dan; Slaby, Ivan; Hammarström, Lars

doi:10.1002/jbmr.5650110704

Cited by 128 publications

(40 citation statements)

References 15 publications

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“…35 Ameloblastin was cloned from an enamel protein in rat incisor tooth germs. 4,7,18 Sheathlin, considered to be part of the same protein as ameloblastin, was recently cloned from porcine tooth germs. 16 An immunohistochemical study using antibodies that recognize different regions of that protein showed that sheathlin is synthesized by ameloblasts and secreted into the immature enamel matrix with posttranslational and postsecretory modifications and that cleaved NH 2 -terminal polypeptides concentrate in the prism sheath.…”

Section: Discussionmentioning

confidence: 99%

Biochemical and Immunohistochemical Characterization of the Amyloid in Canine Amyloid-Producing Odontogenic Tumor

Hirayama

Miyasho

Ohmachi³

et al. 2010

Vet Pathol

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The amyloid of canine amyloid-producing odontogenic tumor (APOT) was evaluated biochemically and immunohistochemically. The N-terminal amino-acid sequence of purified amyloid protein from a canine APOT was strikingly similar to the sequence in both rat ameloblastin and porcine sheathlin. Immunohistochemically, the amyloid in APOT from 9 dogs was strongly reactive with anti-rat ameloblastin, anti-porcine sheathlin, and anti-canine APOT amyloid and weakly reactive with anti-porcine amelogenin but negative for antibodies to cytokeratins, vimentin, desmin, a-smooth muscle actin, amyloid A, glial fibrillary acidic protein, or S100 protein. The neoplastic epithelial cells of APOT were focally reactive with antibodies to ameloblastin, sheathlin, amelogenin, and canine APOT amyloid. The similarity in amino-acid sequence of the amyloid protein of canine APOT to that of enamel proteins, such as ameloblastin, sheathlin, and amelogenin, and the expression of these antigens in both APOT amyloid and in the neoplastic cells suggest that the amyloid of canine APOT is derived from enamel proteins secreted by ameloblasts. Keywords ameloblasts, amyloid, dogs, enamel proteins, odontogenic tumorAmyloidosis is a heterogeneous group of disorders characterized by the deposition of amyloid proteins derived from any of at least 25 different precursor molecules. Amyloid is considered a pathologic substance that appears histologically as an extracellular, amorphous, congophilic protein with applegreen birefringence under polarized light. Amyloidosis can be categorized as systemic or localized. Common human types of localized amyloidosis include amyloidosis of endocrine organs associated (or not) with neoplastic conditions and cerebral amyloidosis of Alzheimer's disease. 21,51 Localized amyloid deposits with or without association with neoplasia also have been described in the human mammary gland, 41,52 respiratory tract, 26,34 gastrointestinal tract, 5,38 genitourinary tract, 13,17 skin, 24,25 and bone. 23 In animals, localized amyloidosis has been associated with neoplastic conditions such as calcifying epithelial odontogenic tumor (CEOT), 2,29 pancreatic endocrine tumor, 28 medullary thyroid carcinoma, 15 ameloblastoma, 10 mammary carcinoma, 43 intestinal carcinoid, 40 extramedullary plasmacytoma, 31,36 and myeloma. 12 CEOT is a rare neoplasm of the tooth-forming apparatus that produces a mineralized substance and amyloid. 30 The origin of the amyloid in human and animal CEOT is often debated but is still unknown. 2,19,27,29,37,42,46 Recent studies indicate that the amyloid in human CEOT is secreted by the neoplastic epithelial cells, but its precise nature remains unclear. 27,39,42 CEOT in veterinary medicine is classified as amyloidproducing odontogenic tumor (APOT). 9,14 In the present study, we partially sequenced the amino acids of the major amyloid protein of canine APOT and compared the amino-terminal sequence with that of the enamel proteins rat ameloblastin and porcine sheathlin, which are transcribed in cells of the epi...

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Section: Discussionmentioning

confidence: 99%

Biochemical and Immunohistochemical Characterization of the Amyloid in Canine Amyloid-Producing Odontogenic Tumor

Hirayama

Miyasho

Ohmachi³

et al. 2010

Vet Pathol

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“…Ameloblastin (AMBN), also known as sheathlin or amelin, is the most abundant nonamelogenin enamel matrix protein (4,5,14) and a member of the secretory calcium-binding phosphoprotein (SCPP) gene cluster of evolutionarily related molecules that regulate skeletal mineralization (13). Further, AMBN induces cell attachment, proliferation, and differentiation of periodontal ligament cells in vitro (34).…”

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confidence: 99%

Ameloblastin Regulates Osteogenic Differentiation by Inhibiting Src Kinase via Cross Talk between Integrin β1 and CD63

Iizuka

Kudo

Yoshida

et al. 2011

Molecular and Cellular Biology

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Ameloblastin, the most abundant nonamelogenin enamel matrix protein, plays a role in ameloblast differentiation. Here, we found that ameloblastin was expressed in osteosarcoma cells; to explore the potential functions of ameloblastin in osteoblasts, we investigated whether this protein is involved in osteogenic differentiation and bone formation on the premise that CD63, a member of the transmembrane-4 glycoprotein superfamily, interacts with integrins in the presence of ameloblastin. Ameloblastin bound to CD63 and promoted CD63 binding to integrin ␤1. The interaction between CD63 and integrin ␤1 induced Src kinase inactivation via the binding of CD63 to Src. The reduction of Src activity and osteogenic differentiation mediated by ameloblastin were abrogated by treatment with anti-CD63 antibody and overexpression of constitutively active Src, respectively. Therefore, our results suggest that ameloblastin is expressed in osteoblasts and functions as a promoting factor for osteogenic differentiation via a novel pathway through the interaction between CD63 and integrin ␤1.Ameloblastin (AMBN), also known as sheathlin or amelin, is the most abundant nonamelogenin enamel matrix protein (4, 5, 14) and a member of the secretory calcium-binding phosphoprotein (SCPP) gene cluster of evolutionarily related molecules that regulate skeletal mineralization (13). Further, AMBN induces cell attachment, proliferation, and differentiation of periodontal ligament cells in vitro (34). In AMBN-null mice, ameloblasts are detached from the matrix, lose cell polarity, and resume proliferation. However, protein expression was not completely inactivated, and truncated RNA missing a portion of exons 5 and 6 is still translated in AMBN knockout (KO) mice (30). Therefore, it is conceivable that exons 5 and 6 of AMBN play a role in ameloblast differentiation (7,30). In this mouse model, structural change was shown in the alveolar bone (30): the alveolar bone exhibited more porosity in truncated-AMBN-expressing mice than in wild-type mice. The changes in alveolar bone in mice lacking exons 5 and 6 of AMBN (AMBN ⌬5-6 ) cannot be directly related to the protein as they could arise from other factors such as changes in occlusal forces in teeth without enamel (30). On the other hand, it has recently been reported that AMBN is expressed in osteoblasts during craniofacial development (25). Although AMBN may play a significant role in not only in tooth development but also bone formation, the role of AMBN in bone formation is still unclear.AMBN has been shown to interact with CD63 via a yeast two-hybrid assay (29). CD63 is a member of the transmembrane-4 glycoprotein superfamily, also known as the tetraspanin family (26,32). Most of these proteins are cell surface proteins that are characterized by the presence of four hydrophobic domains and two extracellular domains (26, 32). CD63 mediates signal transduction events in the regulation of cell survival, development, activation, growth, and motility (12,16,32). In particular, cell surface CD63 is ...

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“…4, 5). Fong et al 17) showed that enamel-related proteins such as amelin were associated with root formation in rats. Tokiyasu et al 18) showed that the enamel matrix derivative activated cementoblasts in vivo and in vitro.…”

Section: Discussionmentioning

confidence: 99%

Individual Variations in the Hardness and Elastic Modulus of the Human Cementum

Yamaguchi

Yao-Umezawa

Tanimoto

et al. 2016

J. Hard Tissue Biology.

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The purpose of this study was to measure the physical properties of enamel and cementum of permanent teeth and to determine the correlation between them. This study was conducted on 50 maxillary premolars that were collected from 26 orthodontic patients (10 males and 21 females, mean age: 19.51 years, range: 12-35 years). The hardness and elastic modulus of the enamel and cementum were measured at the surface of the crown and root at three locations (cervical third: CC, middle third: CM, and apical third: CA). There were individual differences in the hardness and elastic modulus of enamel and cementum. The hardness of the cementum decreased from the cervical to apical regions on the root surfaces in the moderate and soft groups (p<0.01). Individual variations were observed in the hardness and elastic modulus of the human first premolar cementum. A correlation was noted between the hardness and elastic modulus of the enamel and cementum in the CA group (hardness: r=0.551, p<0.01, elastic modulus: r=0.552, P<0.01). These results suggested that the physical properties of cementum may be involved in the occurrence of root resorption caused by orthodontic forces.

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Amelin: An enamel-related protein, transcribed in the cells of epithelial root sheath

Cited by 128 publications

References 15 publications

Biochemical and Immunohistochemical Characterization of the Amyloid in Canine Amyloid-Producing Odontogenic Tumor

Biochemical and Immunohistochemical Characterization of the Amyloid in Canine Amyloid-Producing Odontogenic Tumor

Ameloblastin Regulates Osteogenic Differentiation by Inhibiting Src Kinase via Cross Talk between Integrin β1 and CD63

Individual Variations in the Hardness and Elastic Modulus of the Human Cementum

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