| First Author | Zheng X | Year | 2022 |
| Journal | Bone | Volume | 166 |
| Pages | 116595 | PubMed ID | 36272714 |
| Mgi Jnum | J:330612 | Mgi Id | MGI:7380067 |
| Doi | 10.1016/j.bone.2022.116595 | Citation | Zheng X, et al. (2022) Effects of Fam83h truncation mutation on enamel developmental defects in male C57/BL6J mice. Bone 166:116595 |
| abstractText | Truncation mutations in family with sequence similarity, member H (FAM83H) gene are considered the main cause of autosomal dominant hypocalcified amelogenesis imperfecta (ADHCAI); however, its pathogenic mechanism in amelogenesis remains poorly characterized. This study aimed to investigate the effects of truncated FAM83H on developmental defects in enamel. CRISPR/Cas9 technology was used to develop a novel Fam83h c.1186C > T (p.Q396*) knock-in mouse strain, homologous to the human FAM83H c.1192C > T mutation in ADHCAI. The Fam83h(Q396/Q396) mice showed poor growth, a sparse and scruffy coat, scaly skin and early mortality compared to control mice. Moreover, the forelimbs of homozygous mice were swollen, exhibiting a significant inflammatory response. Incisors of Fam83h(Q396/Q396) mice appeared chalky white, shorter, and less sharp than those of control mice, and energy dispersive X-ray spectroscopy (EDS) analysis and Prussian blue staining helped identify decreased iron and increased calcium (Ca) and phosphorus (P) levels, with an unchanged Ca/P ratio. The expression of iron transportation proteins, transferrin receptor (TFRC) and solute carrier family 40 member 1 (SLC40A1), was decreased in Fam83h-mutated ameloblasts. Micro-computed tomography revealed enamel defects in Fam83h(Q396/Q396) mice. Fam83h(Q396/Q396) enamel showed decreased Vickers hardness and distorted enamel rod structure and ameloblast arrangement. mRNA sequencing showed that the cell adhesion pathway was most notably clustered in LS8-Fam83h-mutated cells. Immunofluorescence analysis further revealed decreased protein expression of desmoglein 3, a component of desmosomes, in Fam83h-mutated ameloblasts. The FAM83H-casein kinase 1alpha (CK1alpha)-keratin 14 (K14)-amelogenin (AMELX) interaction was detected in ameloblasts. And K14 and AMELX were disintegrated from the tetramer in Fam83h-mutated ameloblasts in vitro and in vivo. In secretory stage ameloblasts of Fam83h(Q396/Q396) mice, AMELX secretion exhibited obvious retention in the cytoplasm. In conclusion, truncated FAM83H exerted dominant-negative effects on gross development, amelogenesis, and enamel biomineralization by disturbing iron transportation, influencing the transportation and secretion of AMELX, and interfering with cell-cell adhesion in ameloblasts. |
