AJP - Endocrinology and Metabolism, Vol 260, Issue 6 E833-E838, Copyright © 1991 by American Physiological Society
Fluoride selectively stimulates Na-dependent phosphate transport in osteoblast-like cells
T. Selz, J. Caverzasio and J. P. Bonjour
Department of Medicine, University Hospital of Geneva, Switzerland.
The influence of fluoride (F) on the transport of Pi was investigated in
the osteoblast-like cell line UMR-106. Exposure of cells to F induced a
dose-related stimulation of the Na-coupled Pi transport. Pi transport was
significantly increased 6 h after 1 mM F incubation, with maximal response
observed at 24 h (F 38.0 +/- 2.3, vehicle 19.8 +/- 1.2 pmol.micrograms
DNA-1.4 min-1; P less than 0.001). Na-dependent alanine transport was not
changed by F. The selective effect of F on Pi transport was not associated
with changes in adenosine 3',5'-cyclic monophosphate, cell proliferation,
or alkaline phosphatase activity. However, it was completely blunted by
inhibiting translational processes with cycloheximide. Furthermore, F
enhanced the stimulatory effect on Pi transport of various mitogens such as
fetal calf serum, insulin, and insulin-like growth factor I. In conclusion,
F can selectively enhance the activity of the Pi transport system present
in the plasma membrane of UMR 106 osteoblast-like cells by a mechanism that
probably involves newly synthetized proteins.
