In:
American Journal of Physiology-Cell Physiology, American Physiological Society, Vol. 292, No. 1 ( 2007-01), p. C526-C534
Abstract:
During bone resorption, a large amount of inorganic phosphate (P i ) is generated within the osteoclast hemivacuole. The mechanisms involved in the disposal of this P i are not clear. In the present study, we investigated the efflux of P i from osteoclast-like cells. P i efflux was activated by acidic conditions in osteoclast-like cells derived by the treatment of RAW264.7 cells with receptor activator of nuclear factor-κB ligand. Acid-induced P i influx was not observed in renal proximal tubule-like opossum kidney cells, osteoblast-like MC3T3-E1 cells, or untreated RAW264.7 cells. Furthermore, P i efflux was stimulated by extracellular P i and several P i analogs [phosphonoformic acid (PFA), phosphonoacetic acid, arsenate, and pyrophosphate]. P i efflux was time dependent, with 50% released into the medium after 10 min. The efflux of P i was increased by various inhibitors that block P i uptake, and extracellular P i did not affect the transport of [ 14 C]PFA into the osteoclast-like cells. Preloading of cells with P i did not stimulate P i efflux by PFA, indicating that the effect of P i was not due to transstimulation of P i transport. P i uptake was also enhanced under acidic conditions. Agents that prevent increases in cytosolic free Ca 2+ concentration, including acetoxymethyl ester of 1,2-bis(2-aminophenoxy)ethane- N,N,N′,N′-tetraacetic acid, 2-aminoethoxydiphenyl borate, and bongkrekic acid, significantly inhibited P i uptake in the osteoclast-like cells, suggesting that P i uptake is regulated by Ca 2+ signaling in the endoplasmic reticulum and mitochondria of osteoclast-like cells. These results suggest that osteoclast-like cells have a unique P i uptake/efflux system and can prevent P i accumulation within osteoclast hemivacuoles.
Type of Medium:
Online Resource
ISSN:
0363-6143
,
1522-1563
DOI:
10.1152/ajpcell.00357.2006
Language:
English
Publisher:
American Physiological Society
Publication Date:
2007
detail.hit.zdb_id:
1477334-X
SSG:
12
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