Guangdong Provincial Key Laboratory of Construction and Detection in Tissue Engineering, Guangdong Provincial Key Laboratory of Proteomics and Key Laboratory of Transcriptomics and Proteomics, Ministry of Education of China, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China; College of Stomatology, Southern Medical University, Guangzhou, China.
Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China; College of Stomatology, Southern Medical University, Guangzhou, China.
Biochim Biophys Acta Mol Basis Dis. 2018 Aug;1864(8):2623-2632. doi: 10.1016/j.bbadis.2018.04.015. Epub 2018 Apr 21.
Recent evidence suggests that GTPases Rho family plays an important role in tooth development; however, the role of Cdc42 in tooth development remains unclear. We aimed to investigate the function of Cdc42 in tooth development and amelogenesis. We generated an epithelial cell-specific K5-Cdc42 knockout (KO) mouse to evaluate post-eruption dental phenotypes using a K5-Cre driver line. This model overcomes the previously reported perinatal lethality. Tooth phenotypes were analyzed by micro X-ray, micro-computed tomography (CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), wear rate, shear strength, and a microhardness test. Enamel matrix protein expression was determined by immunohistochemistry. KO mice displayed a hypomaturation phenotype, including incisors that lacked yellow pigmentation and were abnormally white, rapid attrition of molars following eruption, and decreased micro-hardness and shearing strength. Micro-CT data revealed that of incisor and molar enamel volumes were smaller in the KO than in wild-type (WT) mice. SEM analysis showed that the enamel prism structure was disordered. In addition, HE staining indicated a remarkable difference in the ameloblast morphology and function between KO and WT mice, and immunohistochemistry showed increased expression of amelogenin, ameloblastin, matrix metallopeptidase 20, kallikrein-related peptidase 4 and amelotin in the KO mice teeth. Our results suggest epithelium cell-specific Cdc42 deletion leads to tooth hypomaturation and transformation of the enamel prism structure that is likely due to altered ameloblast morphology and the secretion of enamel matrix proteins and proteases. This is the first in vivo evidence suggesting that Cdc42 is essential for proper tooth development and amelogenesis.
最近的证据表明，Rho 家族 GTPases 在牙齿发育中发挥着重要作用；然而，Cdc42 在牙齿发育中的作用尚不清楚。我们旨在研究 Cdc42 在牙齿发育和釉质形成中的功能。我们生成了一种上皮细胞特异性的 K5-Cdc42 敲除（KO）小鼠，使用 K5-Cre 驱动线来评估萌出后牙齿表型。该模型克服了先前报道的围产期致死性。通过微 X 射线、微计算机断层扫描（CT）、扫描电子显微镜（SEM）、能谱（EDX）、磨损率、剪切强度和显微硬度测试分析牙齿表型。通过免疫组织化学测定釉基质蛋白的表达。KO 小鼠表现出低成熟表型，包括切牙缺乏黄色色素且异常发白、萌出后磨牙快速磨损以及微硬度和剪切强度降低。微 CT 数据显示 KO 小鼠的切牙和磨牙釉质体积小于野生型（WT）小鼠。SEM 分析表明，KO 小鼠的釉柱结构紊乱。此外，HE 染色显示 KO 和 WT 小鼠的成釉细胞形态和功能存在显著差异，免疫组织化学显示 KO 小鼠牙齿中釉原蛋白、釉蛋白、基质金属蛋白酶 20、激肽释放酶 4 和釉质蛋白的表达增加。我们的结果表明，上皮细胞特异性 Cdc42 缺失导致牙齿低成熟和釉柱结构的转化，这可能是由于成釉细胞形态的改变以及釉质基质蛋白和蛋白酶的分泌。这是首次在体内证明 Cdc42 对于牙齿正常发育和釉质形成是必需的。
