Epithelial Wnt10a Is Essential for Tooth Root Furcation Morphogenesis
Epithelial Wnt10a Is Essential for Tooth Root Furcation Morphogenesis
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上皮 Wnt10a 对于牙根分叉形态发生至关重要
DOI：
10.1177/0022034519897607
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发表时间：
2020-01-08
影响因子：
7.6
通讯作者：
Han, D.
中科院分区：
文献类型：
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作者：
Yu, M.;Liu, Y.;Han, D.
WNT 10A（Wingless-type MMTV integration site family，member 10A）在牙齿发育中起着至关重要的作用，双等位基因WNT 10A突变的患者和Wnt 10a缺失的小鼠表现为牛牙症。然而，无论是上皮或间充质WNT 10A控制的根分叉形成的启动仍然不清楚，WNT 10A在调节根形态发生的功能意义尚未阐明。在这里，我们通过产生不同组织特异性Wnt 10a条件性敲除小鼠来研究Wnt 10a如何影响牙根发育。在整个组织（EIIa-Cre; Wnt 10aflox/flox）和牙齿上皮（K14-Cre; Wnt 10aflox/flox）中敲除Wnt 10a，导致小鼠磨牙中没有根分叉或根分叉位于根尖，这是一种类似牛牙症的表型。RNAscope分析表明，在根的发育过程中，发生了动态的上皮和间充质Wnt 10a的表达模式。E-cadherin和EdU的免疫荧光染色显示K14-Cre; Wnt 10aflox/flox小鼠在出生后第0天（PN 0），就在牙根形态发生开始之前，磨牙颈部上皮细胞增殖减少。有趣的是，我们发现在PN 4和PN 7时，在K14-Cre; Wnt 10aflox/flox小鼠的磨牙假定根分叉区域中牙髓间充质细胞增殖增加。RNA-seq表明，在磨牙中具有高内源性表达水平的Wnt配体中，在上皮敲除Wnt 10a后，Wnt 4增加。RNAscope检测证实，在K14-Cre; Wnt 10aflox/flox磨牙中，Wnt 4和Axin 2在假定的根分叉区域的牙乳头中的表达增加，其中牙髓过度生长发生。此外，通过Wnt 4 shRNA腺病毒和肾包膜移植物抑制K14-Cre; Wnt 10aflox/flox磨牙中升高的Wnt 4水平后，根分叉缺损得到部分挽救。综上所述，我们的研究提供了第一个体内证据，即上皮Wnt 10a引导根分叉形成，并在根分叉形态发生过程中通过调节适当的Wnt 4表达来控制相邻间充质细胞的有组织增殖中起着至关重要的作用。
WNT10A (Wingless-type MMTV integration site family, member 10A) plays a crucial role in tooth development, and patients with biallelic WNT10A mutation and mice lacking Wnt10a show taurodontism. However, whether epithelial or mesenchymal WNT10A controls the initiation of the root furcation formation remains unclear, and the functional significance of WNT10A in regulating root morphogenesis has not been clarified. Here, we investigated how Wnt10a affects tooth root development by generating different tissue-specific Wnt10a conditional knockout mice. Wnt10a knockout in the whole tissue (EIIa-Cre;Wnt10aflox/flox) and in dental epithelium (K14-Cre;Wnt10aflox/flox) led to an absence of or apically located root furcation in molars of mice, a phenotype that resembled taurodontism. An RNAscope analysis showed that the dynamic epithelial and mesenchymal Wnt10a expression pattern occurred during root development. Immunofluorescent staining of E-cadherin and EdU revealed decreased epithelial cell proliferation at the cervical region of the molar in K14-Cre;Wnt10aflox/flox mice at postnatal day 0 (PN0), just before the initiation of root morphogenesis. Interestingly, we found increased pulpal mesenchymal cell proliferation in the presumptive root furcating region of the molar in K14-Cre;Wnt10aflox/flox mice at PN4 and PN7. RNA-seq indicated that among the Wnt ligands with high endogenous expression levels in molars, Wnt4 was increased after epithelial knockout of Wnt10a. The RNAscope assay confirmed that the expression of Wnt4 and Axin2 in the dental papilla of the presumptive root furcating region, where dental pulp overgrowth occurred, was increased in K14-Cre;Wnt10aflox/flox molars. Furthermore, after suppression of the elevated Wnt4 level in K14-Cre;Wnt10aflox/flox molars by Wnt4 shRNA adenovirus and kidney capsule grafts, the root furcation defect was partially rescued. Taken together, our study provides the first in vivo evidence that epithelial Wnt10a guides root furcation formation and plays a crucial role in controlling the organized proliferation of adjacent mesenchymal cells by regulating proper Wnt4 expression during root furcation morphogenesis.