Phosphate and Calcium Uptake by Rat Odontoblast-Like MRPC-1 Cells Concomitant With Mineralization
作者:P. Lundquist、H. H. Ritchie、K. Moore、T. Lundgren、A. Linde
DOI:10.1359/jbmr.2002.17.10.1801
日期:——
It has been suggested that odontoblasts are instrumental in translocating Ca2+ and inorganic phosphate (Pi) ions during the mineralization of dentin. The aim of this study was to characterize cellular Pi and Ca2+ uptake in the novel rat odontoblast‐like cell line mineralizing rat pulpal cell line (MRPC) 1 during mineralization to see if changes in the ion transport activity would occur as the cultures develop and begin forming a mineralized matrix. MRPC‐1 cells were cultured in chemically defined medium containing ascorbate and Pi, and cultures were specifically analyzed for cellular Pi and Ca2+ uptake activities and expression of type II high‐capacity Na+‐Pi cotransporters. The odontoblast‐like phenotype of the cell line was ascertained by monitoring the expression of collagen type I and dentin phosphopoprotein (DPP). Mineralized nodule formation started at day 9 after confluency and then rapidly increased. Ca2+ uptake by the cells showed a maximum during the end of the proliferative phase (days 5–7). Pi uptake declined to a basal level during proliferation and then was up‐regulated simultaneously with the onset of mineralization to a level fourfold of the basal uptake, suggesting an initiating and regulatory role for cellular Pi uptake in mineral formation. This up‐regulation coincided with a conspicuously increased glycosylation of NaPi‐2a, indicating an activation of this Na+‐Pi cotransporter. The study showed that MRPC‐1 cells express an odontoblast‐like phenotype already at the onset of culture, but that to mineralize the collagenous extracellular matrix (ECM) that formed, a further differentiation involving their ion transporters is necessary.
有研究表明,牙本质细胞在牙本质矿化过程中有助于Ca2+和无机磷酸盐(Pi)离子的转运。本研究的目的是描述新型大鼠牙本质细胞样细胞系矿化大鼠牙髓细胞系(MRPC)1在矿化过程中的细胞Pi和Ca2+摄取特征,以了解离子转运活性是否会随着培养物的发展和矿化基质的形成而发生变化。MRPC-1细胞在含有抗坏血酸和Pi的化学定义培养基中培养,并专门分析细胞Pi和Ca2+摄取活性以及II型高容量Na+-Pi共转运蛋白的表达。通过监测I型胶原蛋白和牙本质磷蛋白(DPP)的表达来确定细胞系的牙本质细胞样表型。矿化结节形成于融合后第9天开始,然后迅速增加。细胞对Ca2+的摄取在增殖期结束时(第5-7天)达到最大值。Pi摄取在增殖期间下降到基础水平,然后在矿化开始时同步上调,达到基础摄取水平的四倍,这表明细胞Pi摄取在矿化形成中起启动和调节作用。这种上调与NaPi-2a糖基化显着增加相吻合,表明这种Na+-Pi共转运蛋白被激活。研究表明,MRPC-1细胞在培养开始时就已经表现出牙本质细胞样表型,但为了使形成的胶原细胞外基质(ECM)