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Biochim Biophys Acta. 2010 Nov;1802(11):1013-9. doi: 10.1016/j.bbadis.2010.07.010. Epub 2010 Jul 25.

Oxidized low density lipoprotein inhibits phosphate signaling and phosphate-induced mineralization in osteoblasts. Involvement of oxidative stress.

Author information

1
INSERM ERI 12 (EA 4292), Amiens, F-80000, France. maziere.cecile@chu-amiens.fr

Abstract

BACKGROUND:

It is well admitted that oxidized LDL (OxLDL) plays a major role in the generation and progression of atherosclerosis. Since atherosclerosis is often accompanied by osteoporosis, the effects of OxLDL on phosphate-induced osteoblast mineralization were investigated.

METHODS:

Calcium deposition, expression of osteoblast markers and inorganic phosphate (Pi) signaling were determined under OxLDL treatment.

RESULTS:

OxLDL, within the range of 10-50 μg protein/ml, inhibited Pi-induced UMR106 rat osteoblast mineralization. In parallel, the expression of Cbfa1/Runx2 transcription factor was decreased, and the intracellular level of the osteoblast marker osteopontin (OPN) was reduced. The extracellular level of another marker, receptor activator of nuclear factor kappa B ligand (RANKL), was also diminished. OxLDL inhibited Pi signaling via ERK/JNK kinases and AP1/CREB transcription factors. OxLDL triggered the generation of reactive oxygen species (ROS), either in the absence or presence of Pi. Furthermore, the effects of OxLDL on Pi-induced mineralization, generation of ROS and extracellular level OPN were reproduced by the lipid extract of the particle, whereas the antioxidant vitamin E prevented them.

CONCLUSIONS:

This work demonstrates that OxLDL, by generation of an oxidative stress, inhibits of Pi signaling and impairs Pi-induced osteoblast differentiation.

GENERAL SIGNIFICANCE:

This highlights the role of OxLDL in bone remodeling and in degenerative disorders other than atherosclerosis, especially in osteoporosis.

PMID:
20667472
DOI:
10.1016/j.bbadis.2010.07.010
[Indexed for MEDLINE]
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