RUNX2 mutation reduces osteogenic differentiation of dental follicle cells in cleidocranial dysplasia
RUNX2 mutation reduces osteogenic differentiation of dental follicle cells in cleidocranial dysplasia
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RUNX2突变减少锁骨颅骨发育不良中牙囊细胞的成骨分化
DOI：
10.1093/mutage/gey010
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发表时间：
2018-05-01
期刊：
影响因子：
2.7
通讯作者：
Zheng, Shuguo
中科院分区：
文献类型：
--
作者：
Liu, Yang;Wang, Yixiang;Zheng, Shuguo
恒牙萌出异常在颅骨锁骨发育不全（CCD）中很常见，这是一种由RUNX2杂合突变引起的骨骼疾病，但其潜在机制仍不清楚。众所周知，牙囊细胞（DFCs）在牙齿萌出中起关键作用，DFCs生物学特性的改变可能导致CCD患者恒牙萌出异常。因此，收集了一名CCD患者和正常对照的原代DFCs，以研究RUNX2突变对DFCs骨重塑活性的影响，并探索该疾病中恒牙萌出受损的机制。保守性和二级结构分析显示，本研究中CCD患者发现的RUNX2突变（c.514delT，p.172fs）位于高度保守的RUNT结构域，并改变了RUNX2的结构。成骨诱导后，我们发现CCD患者中发现的RUNX2突变严重干扰了DFCs的矿化能力以及DFCs中成骨细胞相关基因（包括RUNX2、碱性磷酸酶（ALP）、成骨细胞特异性转录因子（OSX）、骨钙素（OCN）和Ⅰ型胶原α1链（Col I alpha 1））的表达。为了研究CCD患者DFCs的成骨缺陷是否可通过恢复RUNX2来挽救，我们进行了“挽救”实验。令人惊讶的是，通过慢病毒过表达野生型RUNX2，几乎挽救了CCD患者DFCs的成骨缺陷以及成骨细胞相关基因的异常表达。所有这些发现表明，RUNX2突变可通过抑制成骨细胞相关基因降低DFCs的成骨能力，从而干扰牙槽骨形成，而牙槽骨形成是牙齿萌出的动力。这一效应可能为CCD患者恒牙萌出延迟的机制提供有价值的解释和启示。
Disturbed permanent tooth eruption is common in cleidocranial dysplasia (CCD), a skeletal disorder caused by heterozygous mutation of RUNX2, but the mechanism underlying is still unclear. As it is well known that dental follicle cells (DFCs) play a critical role in tooth eruption, the changed biological characteristics of DFCs might give rise to disturbance of permanent tooth eruption in CCD patients. Thus, primary DFCs from one CCD patient and normal controls were collected to investigate the effect of RUNX2 mutation on the bone remodeling activity of DFCs and explore the mechanism of impaired permanent tooth eruption in this disease. Conservation and secondary structure analysis revealed that the RUNX2 mutation (c.514delT, p.172fs) found in the present CCD patient was located in the highly conserved RUNT domain and converted the structure of RUNX2. After osteogenic induction, we found that the mineralised capacity of DFCs and the expression of osteoblast-related genes, including RUNX2, ALP, OSX, OCN and Col I alpha 1, in DFCs was severely interfered by the RUNX2 mutation found in CCD patients. To investigate whether the osteogenic deficiency of DFCs from the CCD patient can be rescued by RUNX2 restoration, we performed 'rescue' experiments. Surprisingly, the osteogenic deficiency and the abnormal expression of osteoblast-associated genes in DFCs from the CCD patient were almost rescued by overexpression of wild-type RUNX2 using lentivirus. All these findings indicate that RUNX2 mutation can reduce the osteogenic capacity of DFCs through inhibiting osteoblast-associated genes, thereby disturbing alveolar bone formation, which serves as a motive force for tooth eruption. This effect may provide valuable explanations and implications for the mechanism of delayed permanent tooth eruption in CCD patients.