Submit Data |  Help |  Video Tutorials |  News |  Publications |  FTP Download |  REST API |  Citing RGD |  Contact   

Type II Na+-Pi cotransporters in osteoblast mineral formation: regulation by inorganic phosphate.

Authors: Lundquist, P  Murer, H  Biber, J 
Citation: Lundquist P, etal., Cell Physiol Biochem. 2007;19(1-4):43-56.
Pubmed: (View Article at PubMed) PMID:17310099
DOI: Full-text: DOI:10.1159/000099191

During calcification of bone, large amounts of phosphate (P(i)) must be transported from the circulation to the osteoid. Likely candidates for osteoblast P(i) transport are the type II sodium-phosphate cotransporters NaPi-IIa and NaPi-IIb that facilitate transcellular P(i) flux in kidney and intestine, respectively. We have therefore determined the 'cotransporters' expression in osteoblast-like cells. We have also studied the 'cotransporters' regulation by P(i) and during mineralization in vitro. Phosphate uptake and cotransporter protein expression was investigated at early, late and mineralizing culture stages of mouse (MC3T3-E1) and rat (UMR-106) osteoblast-like cells. Both NaPi-IIa and NaPi-IIb were expressed by both osteoblast-like cell lines. NaPi-IIa was upregulated in both cell lines one week after confluency. After 7 days in 3mM P(i) NaPi-IIa was strongly upregulated in both cell lines. NaPi-IIb expression was unaffected by both culture stage and P(i) supplementation. The expression of both cotransporters was unaffected by P(i) deprivation. In vitro mineralization at 1.5mM P(i) was preceded by a three-fold increase in osteoblast sodium-dependent P(i) uptake and a corresponding upregulation of both NaPi-IIa and NaPi-IIb. Their expression thus seem regulated by phosphate in a manner consistent with their playing a role in transcellular P(i) flux during mineralization.


Gene Ontology Annotations
Objects Annotated

Additional Information

RGD Object Information
RGD ID: 7243138
Created: 2013-05-08
Species: All species
Last Modified: 2013-05-08
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.