Premium
Phosphate and Calcium Uptake by Rat Odontoblast‐Like MRPC‐1 Cells Concomitant With Mineralization
Author(s) -
Lundquist P.,
Ritchie H. H.,
Moore K.,
Lundgren T.,
Linde A.
Publication year - 2002
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.2002.17.10.1801
Subject(s) - phosphate , concomitant , mineralization (soil science) , calcium , chemistry , odontoblast , biochemistry , medicine , dentistry , nitrogen , dentin , organic chemistry
It has been suggested that odontoblasts are instrumental in translocating Ca 2+ and inorganic phosphate (P i ) ions during the mineralization of dentin. The aim of this study was to characterize cellular P i and Ca 2+ 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 P i , and cultures were specifically analyzed for cellular P i and Ca 2+ uptake activities and expression of type II high‐capacity Na + ‐P i 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. Ca 2+ uptake by the cells showed a maximum during the end of the proliferative phase (days 5–7). P i 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 P i uptake in mineral formation. This up‐regulation coincided with a conspicuously increased glycosylation of NaPi‐2a, indicating an activation of this Na + ‐P i 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.