Hypophosphatasia-associated deficiencies in mineralization and gene expression in cultured dental pulp cells obtained from human teeth.
Hypophosphatasia-associated deficiencies in mineralization and gene expression in cultured dental pulp cells obtained from human teeth.
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DOI：
10.1016/j.joen.2012.02.008
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发表时间：
2012-07
影响因子：
4.2
通讯作者：
Nociti FH Jr
中科院分区：
文献类型：
--
作者：
Rodrigues TL;Foster BL;Silverio KG;Martins L;Casati MZ;Sallum EA;Somerman MJ;Nociti FH Jr
低磷症(HPP)中ALPL基因的突变降低了组织中非特异性碱性磷酸酶的功能，由此导致的焦磷酸(PPI)增加通过抑制生理性钙磷(PI)的沉淀而导致骨和牙齿的矿化缺陷。虽然牙周表型有很好的文献记载，但牙髓/牙本质异常在临床文献中已被提出，尽管报道多种多样，潜在的机制仍不清楚。体外分析用于确定与HPP相关的牙髓/牙本质表型相关的机制。建立HPP受试者原代培养的牙髓细胞，以检测碱性磷酸酶(ALP)活性、矿化和基因表达，并与健康对照细胞进行比较。在细胞培养中，将外源PI提供给正确的PI/PPI比率。与对照组相比，HPP细胞的碱性磷酸酶活性(50%)和矿物质结节形成(60%)显著降低。PPI调节基因在HPP牙髓细胞中的表达发生改变，包括进行性强直基因(ANKH)的减少和ENPP1的增加。HPP细胞成牙本质细胞标志物基因表达下调，包括还原骨桥蛋白(OPN)、牙本质基质蛋白1(DMP1)、牙本质涎磷蛋白(DSPP)和基质细胞外磷酸蛋白(MEPE)。PI的加入为矿化提供了一种纠正措施，并部分挽救了一些基因的表达，尽管细胞保留了PPI相关基因的信使RNA水平。这些研究表明，在HPP条件下，牙髓细胞矿化能力受损，成牙本质细胞特征被破坏，这为理解HPP中观察到的牙本质表型的分子机制提供了第一步。
Mutations in the gene ALPL in hypophosphatasia (HPP) reduce the function of tissue nonspecific alkaline phosphatase, and the resulting increase in pyrophosphate (PPi) contributes to bone and tooth mineralization defects by inhibiting physiologic calcium-phosphate (Pi) precipitation. Although periodontal phenotypes are well documented, pulp/dentin abnormalities have been suggested in the clinical literature although reports are variable and underlying mechanisms remains unclear. In vitro analyses were used to identify mechanisms involved in HPP-associated pulp/dentin phenotypes. Primary pulp cells cultured from HPP subjects were established to assay alkaline phosphatase (ALP) activity, mineralization, and gene expression compared with cells from healthy controls. Exogenous Pi was provided to the correct Pi/PPi ratio in cell culture. HPP cells exhibited significantly reduced ALP activity (by 50%) and mineral nodule formation (by 60%) compared with the controls. The expression of PPi regulatory genes was altered in HPP pulp cells, including reduction in the progressive ankylosis gene (ANKH) and increased ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). Odontoblast marker gene expression was disrupted in HPP cells, including reduced osteopontin (OPN), dentin matrix protein 1 (DMP1), dentin sialophosphoprotein (DSPP), and matrix extracellular phosphoprotein (MEPE). The addition of Pi provided a corrective measure for mineralization and partially rescued the expression of some genes although cells retained altered messenger RNA levels for PPi-associated genes. These studies suggest that under HPP conditions pulp cells have the compromised ability to mineralize and feature a disrupted odontoblast profile, providing a first step toward understanding the molecular mechanisms for dentin phenotypes observed in HPP.