The analysis of enamel malformation in type VII collagen knockout mice.

隐性营养不良性大疱性表皮病（RDEB）是由编码VII型胶原（COL 7）的基因突变引起的，该基因是表皮基底膜区锚定原纤维的主要成分。我们研究了牙齿釉质结构的RDEB患者的扫描电子显微镜。它显示不规则的釉质棱柱，表明结构性釉质缺陷。Col 7a 1-/-小鼠的釉质钙化和化学组成与野生型相似。然而，Col 7a 1-/-小鼠牙齿的横切面显示出不规则的釉质棱柱，这也在RDEB患者中观察到。此外，Col 7a 1-/-小鼠牙齿的成釉细胞分化不良，缺乏正常的釉质蛋白分泌Tomes过程，并且显示出釉原蛋白和其他釉质相关分子的mRNA表达减少。这些发现表明，COL 7调节成釉细胞分化，是必不可少的Tomes过程的形成。

Recessive dystrophic epidermolysis bullosa (RDEB) is caused by mutations in the gene encoding type VII collagen (COL7), a major component of anchoring fibrils in the epidermal basement membrane zone. We examined the tooth enamel structure of an RDEB patient by scanning electron microscopy. It showed irregular enamel prisms, indicating structural enamel defects. The enamel calcification and chemical composition of Col7a1-/- mice were similar to those of the wild type. However, transverse sections of teeth from the Col7a1-/- mice showed irregular enamel prisms, which were also observed in the RDEB patient.Furthermore, the Col7a1-/- mice teeth had poorly differentiated ameloblasts, lacking normal enamel protein-secreting Tomes processes, and showed reduced mRNA expression of amelogenin and other enamel-related molecules. These findings suggest that COL7 regulates ameloblast differentiation and is essential for the formation of Tomes processes.