Enamel Defects Associated With Dentin Sialophosphoprotein Mutation in Mice.
Enamel Defects Associated With Dentin Sialophosphoprotein Mutation in Mice.
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DOI：
10.3389/fphys.2021.724098
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发表时间：
2021
影响因子：
4
通讯作者：
Lu Y
中科院分区：
文献类型：
--
作者：
Liang T;Xu Q;Zhang H;Wang S;Diekwisch TGH;Qin C;Lu Y
牙本质唾液酸磷蛋白（DSPP）是一种细胞外基质蛋白，在成牙本质细胞中高度表达，但在牙齿发育过程中仅在分泌前成釉细胞中短暂表达。我们之前生成了表达人类突变体DSPP（p.P17L；称为“DsppP19L/+”）的小鼠等效物（DSPP，p.P19L）的敲入小鼠模型，并报道DsppP19L/+和DsppP19L/P19L小鼠表现出类似于人类牙本质发育不全（DGI）的牙本质表型。在本研究中，我们分析了突变体 P19L-DSPP 对 DsppP19L/+ 和 DsppP19L/P19L 小鼠牙釉质发育的致病作用。对 7 周龄小鼠下颌切牙的微计算机断层扫描 (μCT) 分析表明，DsppP19L/P19L 小鼠在所检查的牙釉质形成的不同阶段的牙釉质体积和/或牙釉质密度显着降低。小鼠门牙酸蚀扫描电镜（SEM）分析表明，在牙釉质形成的中晚期成熟阶段，野生型小鼠牙釉质已出现明显的牙釉质棒交叉图案，而DsppP19L/+小鼠仅发现微小颗粒，DsppP19L/P19L小鼠牙釉质未见明显结构。然而，当门牙釉质即将长出口腔时，DsppP19L/+ 小鼠中明显有明显的交叉牙釉质棒，但 DsppP19L/P19L 小鼠中仅显示出不明确的牙釉质棒。此外，下颌第一磨牙的μCT分析显示，DsppP19L/+和DsppP19L/P19L小鼠在出生后2、3和24周龄时牙釉质体积和牙釉质密度显着减少。背散射和酸蚀 SEM 分析显示，虽然 3 周龄的 DsppP19L/+ 小鼠下颌第一磨牙中的牙釉质棒模式与年龄匹配的野生型小鼠相似，但在 DsppP19L/P19L 小鼠中没有观察到明显的牙釉质棒。然而，根据反向散射和酸蚀 SEM 判断，DsppP19L/+ 和 DsppP19L/P19L 小鼠在 24 周龄时下颌第一磨牙均未显示出清晰的牙釉质棒。原位杂交显示，分泌前成釉细胞中 DSPP mRNA 水平显着降低，但免疫组织化学显示，Dspp 突变小鼠的分泌前成釉细胞中 DSP/DSPP 免疫染色信号比野生型小鼠强得多。这些结果表明，突变型 P19L-DSPP 蛋白导致小鼠牙釉质发育缺陷，这可能与分泌前成釉细胞中突变型 DSPP 的细胞内滞留有关。
Dentin sialophosphoprotein (DSPP) is an extracellular matrix protein that is highly expressed in odontoblasts, but only transiently expressed in presecretory ameloblasts during tooth development. We previously generated a knockin mouse model expressing a mouse equivalent (DSPP, p.P19L) of human mutant DSPP (p.P17L; referred to as “DsppP19L/+”), and reported that DsppP19L/+ and DsppP19L/P19L mice manifested a dentin phenotype resembling human dentinogenesis imperfecta (DGI). In this study, we analyzed pathogenic effects of mutant P19L-DSPP on enamel development in DsppP19L/+ and DsppP19L/P19L mice. Micro-Computed Tomography (μCT) analyses of 7-week-old mouse mandibular incisors showed that DsppP19L/P19L mice had significantly decreased enamel volume and/or enamel density at different stages of amelogenesis examined. Acid-etched scanning electron microscopy (SEM) analyses of mouse incisors demonstrated that, at the mid-late maturation stage of amelogenesis, the enamel of wild-type mice already had apparent decussating pattern of enamel rods, whereas only minute particulates were found in DsppP19L/+ mice, and no discernible structures in DsppP19L/P19L mouse enamel. However, by the time that incisor enamel was about to erupt into oral cavity, distinct decussating enamel rods were evident in DsppP19L/+ mice, but only poorly-defined enamel rods were revealed in DsppP19L/P19L mice. Moreover, μCT analyses of the mandibular first molars showed that DsppP19L/+ and DsppP19L/P19L mice had a significant reduction in enamel volume and enamel density at the ages of 2, 3, and 24weeks after birth. Backscattered and acid-etched SEM analyses revealed that while 3-week-old DsppP19L/+ mice had similar pattern of enamel rods in the mandibular first molars as age-matched wild-type mice, no distinct enamel rods were observed in DsppP19L/P19L mice. Yet neither DsppP19L/+ nor DsppP19L/P19L mice showed well-defined enamel rods in the mandibular first molars by the age of 24weeks, as judged by backscattered and acid-etched SEM. In situ hybridization showed that DSPP mRNA level was markedly reduced in the presecretory ameloblasts, but immunohistochemistry revealed that DSP/DSPP immunostaining signals were much stronger within the presecretory ameloblasts in Dspp mutant mice than in wild-type mice. These results suggest that mutant P19L-DSPP protein caused developmental enamel defects in mice, which may be associated with intracellular retention of mutant DSPP in the presecretory ameloblasts.
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影响因子：
2.7
作者：
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通讯作者：
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作者：
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通讯作者：
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影响因子：
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作者：
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