[email protected] (受疫情影响,东南亚目前只开放曼谷诊所)
全周 (9AM - 5PM)

我们和你在一起

Extra info thumb
  • 总部: 泰国曼谷市巴吞汪区仑披尼分区 普勒吉路齐隆巷5号.
  • [email protected]
AMELOTIN; AMTN

AMELOTIN; AMTN

HGNC Approved Gene Symbol: AMTNCytogenetic location: 4q13.3 Genomic coordinates (GRCh38): 4:70,518,568-70,532,742 (from NCBI)▼ DescriptionThe mineralized por...

HGNC Approved Gene Symbol: AMTN

Cytogenetic location: 4q13.3 Genomic coordinates (GRCh38): 4:70,518,568-70,532,742 (from NCBI)

▼ Description
The mineralized portions of teeth, the dentin and enamel, are formed by mesenchyme-derived odontoblasts and epithelium-derived ameloblasts, respectively. As ameloblasts differentiate, they deposit specific proteins necessary for enamel formation, including amelogenin (AMELX; 300391), enamelin (ENAM; 606585), and ameloblastin (AMBN; 601259), in the organic enamel matrix. Amelotin is specifically expressed in maturation-stage ameloblasts (Iwasaki et al., 2005).

▼ Cloning and Expression
Iwasaki et al. (2005) identified Amtn as an ameloblast-specific gene by differential display PCR of various microdissected cell types of the dental organ from 10-day-old mouse incisors. By database analysis, they identified human AMTN, which encodes a predicted 209-amino acid protein that is 60% identical to the 213-amino acid mouse protein. The mouse and human proteins both contain N-terminal signal sequences and are rich in proline, leucine, and threonine. Northern blot analysis of postnatal and adult mouse tissues showed that Amtn was expressed exclusively in teeth. In situ hybridization analysis revealed that Amtn was expressed only in maturation-stage ameloblasts during mouse tooth development. Amtn protein was efficiently secreted from transfected cells in culture.

Moffatt et al. (2006) cloned rat and pig Amtn. They determined that AMTN is conserved in mammals, but is absent in fish, birds and amphibians. Immunofluorescence analysis of mouse and rat mandible localized Amtn protein in the basal lamina of maturation-stage ameloblasts of incisors and unerupted molars. Amtn was also detected in the internal basal lamina of junctional epithelium in molars.

▼ Gene Structure
Iwasaki et al. (2005) determined that the AMTN gene contains 9 exons.

▼ Mapping
By genomic sequence analysis, Iwasaki et al. (2005) mapped the AMTN gene to chromosome 4q13.3, immediately proximal to the AMBN and ENAM genes. They mapped the mouse gene to a region of chromosome 5 that shows homology of synteny to human chromosome 4q13.3.

▼ Molecular Genetics
In a Costa Rican family segregating autosomal dominant hypomineralized amelogenesis imperfecta (AI3B; 617607), Smith et al. (2016) identified a heterozygous deletion/insertion mutation in the amelotin gene (610912.0001) that segregated with the phenotype in the family. The mutation was predicted to result in an in-frame deletion of 92 amino acids, shortening the protein from 209 to 117 residues. The deletion was not present in the Database of Genomic Variants. No functional studies were performed.

▼ Animal Model
Nakayama et al. (2015) generated Amtn-deficient mice and observed that null and heterozygous animals were normal except for a pronounced delay in enamel mineralization in the maturation stage of tooth development. Enamel thickness was not affected. The mandibular incisors in particular showed delayed mineralization and a tendency to chip. In contrast, maxillary incisors and molars in these mice showed some discoloration but no signs of enamel attrition.

▼ ALLELIC VARIANTS ( 1 Selected Example):

.0001 AMELOGENESIS IMPERFECTA, TYPE IIIB (1 family)
AMTN, 8,678-BP DEL/4-BP INS
In affected members of a Costa Rican family with autosomal dominant hypomineralized amelogenesis imperfecta (AI3B; 617607), Smith et al. (2016) identified heterozygosity for an 8,678 bp deletion, encompassing exons 3-6, as well as a 4-bp insertion in the amelotin gene (chr4.71,385,896-71,394,573delinsCTCA, GRCh37). The mutation segregated with the phenotype and was predicted to result in an in-frame deletion of 92 amino acids (Gln19_Gln110del), shortening the protein from 209 to 117 residues. The deletion was not present in the Database of Genomic Variants. No functional studies were performed.

Tags: 4q13.3